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Although atmospheric pressure plasma jets (APPJs) have been widely employed for materials modification, they have some drawbacks, such as the small treatment area (couple of cm2). To overcome this limitation, a funnel-like APPJ with a wide exit has been proposed. In this work, a gas-permeable cotton cloth covered the nozzle of the device to improve the gas flow dynamics and increase its range of operation. The funnel jet was flushed with Ar, and the plasma was ignited in a wide range of gas flow rates and the gap distances between the exit nozzle and the sample holder. The device characterization included electric measurements and optical emission spectroscopy (OES). To evaluate the size of the treatment and the degree of surface modification, large samples of high-density polyethylene (PE) were exposed to plasma for 5 min. Afterward, the samples were analyzed via water contact angle WCA measurements, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It was found that surface modification occurs simultaneously on the top and bottom faces of the samples. However, the treatment incorporated different functional groups on each side. [ABSTRACT FROM AUTHOR]

A nanosecond atmospheric pressure plasma jet operated in pure nitrogen is studied by spatially and temporally resolved optical emission spectroscopy complementing the companion paper (Kuhfeld et al 2023 Plasma Sources Sci. Technol. 32 084001), where the discharge is investigated by means of Particle-in-Cell/Monte Carlo collisions (PIC/MCC) simulations and fluid models. Two temporal phases of the evolution of the discharge are identified: a fast breakdown and a quasi-DC phase. It is shown that during the breakdown phase several ionization waves develop, while after the breakdown the discharge has a structure similar to DC glow discharges, in agreement with the modeling predictions. The results of the measurements of the spatial-temporal dynamics of the light emission are compared with the distribution of densities of the N 2 + ( B 2 Σ u +) and N 2 ( C 3 Π u) states reconstructed from the PIC/MCC simulations. A good agreement is demonstrated. [ABSTRACT FROM AUTHOR]

The present study investigates the physics of a nanosecond-pulsed microplasma operated at a pressure of 200 mbar with the help of a particle-in-cell simulation with Monte Carlo treatment of collision (PIC/MCC) and (semi-)analytical models. The discharge is ignited in a 1 mm gap between two parallel molybdenum electrodes by applying a voltage in the kV-range for several tens to hundreds of nanoseconds. A PIC/MCC simulation code is developed in order to describe the experiment performed under identical conditions. The simulation includes the external electrical circuit to perform ab-initio calculations of the complete experimental setup. Notable features of the PIC/MCC are (i) the adjustment of super-particle weights to reduce the computational load during drastic changes of the plasma density, which reaches values up to a few 10 19 m − 3 , and (ii) the inclusion of dissociative recombination of the N 4 + ions, which is the key loss process for the charge carriers in the plasma bulk regions. The current and voltage waveforms obtained from the simulation are compared to the experimentally measured ones and good agreement is found. After ignition, the discharge establishes a quasi-steady state exhibiting spatial features similar to a conventional DC glow discharge. Using the PIC/MCC results, reasonable approximations are identified, which allow the development of various analytical fluid models for the individual plasma regions. These models are able to reproduce the key features of the discharge in agreement with the PIC/MCC results. The simplified models for the different discharge regions can be combined to describe the global behaviour of the discharge and—in a next step—might be used to develop computationally efficient global chemistry models that account for the different power dissipation mechanisms along the discharge gap. [ABSTRACT FROM AUTHOR]

Simple Summary: Cancer is a devastating disease. New treatment avenues are demanded to promote successful and safe cancer therapies. Gas plasma is a novel tool recently promoted for cancer treatment. This so-called fourth state of matter is known in its hotter forms, such as fire and lightning. Technology leap innovations enabled the usage of gas plasma for medical purposes. In laboratory models, gas plasma has shown promising antitumor effects in several types of cancer. One particularly successful gas plasma device type is called jet plasma. We here attempted to optimize those by testing two adapters mountable on plasma jet devices, which have two functions. One is to increase the amount of ambient air, similar to a turbo coming close to the plasma jet, to produce more free radicals within the same time for anticancer treatment. The second is to add a filter with varying porosity between the plasma jet and the treatment target. This increases the area of free radical deposition, potentially enabling larger skin or tumor treatment areas compared to the focused treatment area of the plasma jet alone. We here provide evidence that such a filter enhanced the antitumor effects of a certified argon plasma jet. Medical gas plasma is an experimental technology for anticancer therapy. Here, partial gas ionization yielded reactive oxygen and nitrogen species, placing the technique at the heart of applied redox biomedicine. Especially with the gas plasma jet kINPen, anti-tumor efficacy was demonstrated. This study aimed to examine the potential of using passive flow shaping to enhance the medical benefits of atmospheric plasma jets (APPJ). We used an in-house developed, proprietary Modular Nozzle System (MoNoS; patent-pending) to modify the flow properties of a kINPen. MoNoS increased the nominal plasma jet-derived reactive species deposition area and stabilized the air-plasma ratio within the active plasma zone while shielding it from external flow disturbances or gas impurities. At modest flow rates, dynamic pressure reduction (DPR) adapters did not augment reactive species deposition in liquids or tumor cell killing. However, MoNoS operated at kINPen standard argon fluxes significantly improved cancer organoid growth reduction and increased tumor immunogenicity, as seen by elevated calreticulin and heat-shock protein expression, along with a significantly spurred cytokine secretion profile. Moreover, the safe application of MoNoS gas plasma jet adapters was confirmed by their similar-to-superior safety profiles assessed in the hen's egg chorioallantoic membrane (HET-CAM) coagulation and scar formation irritation assay. [ABSTRACT FROM AUTHOR]

Cold atmospheric pressure plasmas (CAPs) have a promising application in cancer treatment, the needle‐ring electrodes plasma jet is one of the common CAPs sources. Here, we compared the discharge characteristics and anticancer effects in two plasma jets: solid electrode and hollow electrode with six working gases (He, He + 0.5%O2, He + 0.5%N2, Ar, Ar + 0.5%O2, and Ar + 0.5%N2). The results show the solid plasma jet is slightly stronger according to discharge image, optical emission spectroscopy, and concentration of H2O2 and NO2−. We used the leukemia cell THP‐1 as the model to detect the anticancer effect, cell viability assay demonstrated a solid electrode plasma jet with He + 0.5%N2 has less cell survival. Moreover, apoptosis increased significantly as the plasma treatment time and Cleaved‐PARP1 upregulated, SOD1 and p21 downregulated in a time‐dependent manner. Our work suggested that a solid electrode plasma jet with He + 0.5%N2 may be a novel therapeutic method for acute myeloid leukemia. [ABSTRACT FROM AUTHOR]

The lifetime of mirrors in outdoor conditions is crucial in the correct operation of any concentrating solar power (CSP) installation. In this work, the corrosion behavior of two types of metallized surfaces was studied. The first was made of a flexible polymer having a deposited reflective silver metallic film. The second was made of the same surface type with a dielectric SiO2 protection coating by an atmospheric pressure plasma jet. Polycarbonate sheets were used as substrates on which metallic silver was deposited by the Dynamic Chemical Deposit technique. This electroless technique allowed producing the mirror finishing under environmental conditions by sequentially spraying; as aerosols projected towards the substrate surface, the activation and reducing-oxidizing solutions with rinsing after each one. The silver coatings were about 100 nm thick. Environmental and accelerated weathering degradation and salt and sulfide fogs were carried out. XPS analyses show that the corrosion products formed were Ag2S, AgCl, and Ag2O. It was observed that the tarnishing was initiated locally by the formation of Ag2S columns as eruptions on the surface. Subsequently, the ions diffused through the protective layer and into the silver reflective layer, chemically reacting with the silver. The main atmospheric agents were H2S, chloride particles, and HCl. High reflectance was initially obtained of about 95%. The obtained results suggest mechanisms for the degradation of exposed silver surfaces to moisturized atmospheres with corrosive compounds. [ABSTRACT FROM AUTHOR]

Organosilicon films were deposited on SAE 1020 steel by an atmospheric pressure plasma jet system using hexamethyldisiloxane (HMDSO) monomer as a polymerizing agent. Several experimental parameters, such as deposition mode (continuous or alternated), deposition time, and number of deposition steps, were varied to obtain stable coatings with improved corrosion resistance. To evaluate the surface characteristics of the obtained films, the following analyses were performed: water contact angle (WCA) measurements, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Additionally, some electrochemical analyses like open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and linear potentiodynamic polarization measurements were carried out to evaluate the corrosion resistance and the stability of the obtained films. From these results, it can be concluded that the corrosion resistance of the coated samples increased significantly when compared to the pristine SAE 1020 steel. Moreover, the three-step deposition process was more efficient in promoting corrosion resistance than the continuous film deposition. [ABSTRACT FROM AUTHOR]

Plasma catalysis is a promising approach to further enhance the conversion of methane into value-added products such as methanol. In this work, the mechanisms enabling the conversion of methane to CO, CO2 and methanol enabled by plasma-enhanced catalysis were investigated. A catalyst reactor was incorporated downstream of the plasma jet to enable the separation between plasma generation and the catalyst bed. An enhancement in CH3OH and CO2 production was observed for the shortest distance between the plasma and catalyst compared to the plasma-only case. Plasma-enabled gas heating was shown not to be responsible for the observed synergy while a gas temperature increase as low as 30–40 K significantly impacted desorption rates of CH3OH/C2H5OH on alumina particles. Correlations between molecular beam mass spectrometry (MBMS) measurements at the inlet and outlet of the catalytic reactor suggest that the observed synergistic effect was caused by radical species most likely the CH3O2 radical. This study shows that surface reactions induced by radicals such as alkylperoxy radicals might play an important role in surface reactions in plasma-catalysis. [ABSTRACT FROM AUTHOR]

Ionic species in atmospheric pressure plasma jets (APPJs) play an important role in plasma-surface and plasma-liquid interactions, nonetheless, they have not received the same attention as their neutral reactive species counterparts. In this work, a molecular beam mass spectrometer (MBMS) was used to characterize the ion compositions in the effluent of an APPJ operating in ambient air for different feed gases including Ar + O2, Ar + air and Ar + H2O mixtures inspired by gas compositions used for biomedical applications. Changes in compositions of positive and negative ions as a function of nozzle-to-substrate distance along the plasma plume were analyzed and compared with a pseudo-1D plug flow model. Positive and negative ions were detected up to distances of 12 mm from the visible plasma plume tip. The measurements enable to follow the ion conversion pathways in the effluent of the APPJs as a function of distance from the nozzle. The trends in ion yield obtained from a pseudo-1D plug flow model showed generally a good agreement with the experimentally observed trends after addition of ionic reactions to the previously reported reaction set but also some distinctive differences were observed. The dominant positive ions in the far effluent are water ion clusters, the most stable ion for all gas mixtures investigated, while a large variety of negative ions was found for different gas mixtures. [ABSTRACT FROM AUTHOR]

Low-temperature, atmospheric pressure plasma presents a new, inexpensive, and environmentally friendly method of water purification. For long duration crewed space missions, a novel water purification system that does not rely on consumable filters and chemicals would be desirable. Plasma systems provide a viable option for these missions, but their operation and designs need to be optimized and compared to existing technology. For this application, gas and power usage are key limiting factors. In this work, water contaminated with methylene blue is purified with plasma. The rate of purification, gas flow usage, and power consumption are compared for multiple devices. A single atmospheric pressure plasma jet is compared with jet array configurations and a novel, 3D printed "plasma sheet" design that expands the size of the plasma surface area. A resource gauge parameter was developed to compare the resource usage and purification rate of each device, and this parameter showed that the plasma sheet was able to improve the rate of purification without increasing resource usage. Additionally, two types of jet arrays were designed that demonstrated the need to exceed a minimum energy and flow rate threshold to maintain effective treatment. A low cost jet was also developed that showed suitable treatment results with a two order of magnitude cost reduction. Finally, a figure of merit was discussed to compare the best performing plasma device with the urine processor assembly used on the International Space Station. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atmospheric Pressure Plasma Jet allowed obtaining a noble self-assembled GO coating. • The self-assembled GO coating was heat-treated to obtain rGO. • The rGO electrical conductivity increased as a result of losing oxygen in the treatment. • The plasma eliminated OH groups allowing self-assembling GO particles for a laminar coating. • Interference colors show the thickness and the planes generated with GO particles. This work uses an atmosphere-pressure plasma jet to obtain thin, homogeneous graphene oxide coatings. The films consisted of self-assembled graphene oxide (GO) layers, which were reduced by heat treatment under a reductive hydrogen atmosphere to obtain a reduced graphene oxide film. The electrochemical and photoelectrochemical analyses show that electrical conductivity increases after the reduction process; meanwhile, this process eliminates the p-type photoactivity of the graphene oxide film. The reduced graphene oxide X-ray diffraction pattern revealed the elimination of the signal at 2θ = 11° initially found in the graphene oxide film. The C1s and O1s high-resolution XPS analyses of the reduced graphene oxide film reveal a pronounced increase in the graphitic-like carbon (sp2), whereas a decrease in the organic-like carbon (sp3) and oxygenated species, such as C-OH, C-O-C, C O, and O C OH, initially found in the graphene oxide film. [ABSTRACT FROM AUTHOR]

Introduction The aim of this study was toinvestigate the sterilization potential of atmospheric pressure plasma jet (APPJ) and interactions of this technology with double-stranded DNA using the polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) techniques. Materials and Methods The plasma jet was produced through a high voltage sinusoidal power supplyusing a mixture of argon and oxygen gases with theflow rate of 1 L/min. Escherichia coli cells and double-stranded DNA (dsDNA) fragments were amplified by T7 universal primer through the PCR technique and treated with argon/oxygen APPJ at different exposure times. The data were analyzed by the agarose and polyacrylamide gel electrophoresis, SSCP and renewed PCR techniques. Results According to the results of the study, the APPJ could serve as an effective instrument for sterilization at > 30 sec discharge. The destruction of DNA was detectable by different techniques after 120 sec from APPJ discharge. Conclusion Our findings revealed that the active species of plasma can lead to cell death. These species may break or nick the dsDNA, exchange DNA nucleotides, and lead to transition and transversion mutations. These mutagenesis effects of APPJ might be the reason of microorganism cell death after the treatment in addition to other destructive effects of APPJ on macromolecules.

To overcome challenges for manufacturing of modern smart medical plastic parts by injection molding, e.g. for active implants, the optimization of the interface between electronics and the polymer component concerning adhesion and diffusion behavior is crucial. Our results indicate that a nano-sized SiOxCyHz layer formed by plasma-enhanced chemical vapour deposition (PE-CVD) via open air atmospheric pressure plasma jet (APPJ) and by use of a hexamthyldisiloxane (HMDSO) precursor can form a non-corrosive, anti-permeable and biocompatible coating. Due to the open air character of the APPJ process an inline coating before overmolding could be an easy applicable method and a promising advancement.

Open air atmospheric pressure plasma jet (APPJ) enhanced chemical vapour deposition process was used to deposit biocompatible SiOx/TiOx composite coatings. The as deposited films are hydrophilic and show visible light induced photocatalytic effect, which is a consequence of the formation of defects in the TiOx structure due to the plasma process. This photocatalytic effect was verified by the demonstration of an antimicrobial effect under visible light on E. coli as well as by degradation of Rhodamine B. The films are non-cytotoxic as shown by the cytocompatibility tests. The films are conductive to cell growth and are stable in DMEM and isopropanol. The structural evaluation using SEM, EDS and XPS shows a dispersion of TiOx phase in a SiOxCyHz matrix. These analyses were used to correlate the structure-property relationship of the composite coating.

The adherence of wet fabrics to the skin brings much discomfort. The relationship between hydrophilicity and adhesion properties of fabric materials is investigated. A theoretical expression is given to describe the relationship of adhesion force, water contact angle (WCA), and radius of fabric–liquid interface. The adhesion force grows with decreasing WCA and increasing radius of the fabric–liquid interface. With the help of atmospheric pressure plasma jet (APPJ) treatment, the hydrophilicity of the fabric materials is improved, accompanied by reduced WCA, roughened fiber surfaces, as observed by scanning electronic microscope (SEM), and increased Oxygen/Carbon (O/C) atomic ratio and polar bonds, analyzed by X-ray photoelectron spectroscopy (XPS). In accordance with the theoretical conclusion, the APPJ treated fabrics have a much larger maximum adhesion force and longer adhesion duration with water, indicating more discomfort resulting from the increase of hydrophilicity when they are wet. To minimize the discomfort caused by wet adhesion, less hydrophilic fabric surfaces may be preferred. [ABSTRACT FROM AUTHOR]

The adherence of wet fabrics to the skin brings much discomfort. The relationship between hydrophilicity and adhesion properties of fabric materials is investigated. A theoretical expression is given to describe the relationship of adhesion force, water contact angle (WCA), and radius of fabric-liquid interface. The adhesion force grows with decreasing WCA and increasing radius of the fabric-liquid interface. With the help of atmospheric pressure plasma jet (APPJ) treatment, the hydrophilicity of the fabric materials is improved, accompanied by reduced WCA, roughened fiber surfaces, as observed by scanning electronic microscope (SEM), and increased Oxygen/Carbon (O/C) atomic ratio and polar bonds, analyzed by X-ray photoelectron spectroscopy (XPS). In accordance with the theoretical conclusion, the APPJ treated fabrics have a much larger maximum adhesion force and longer adhesion duration with water, indicating more discomfort resulting from the increase of hydrophilicity when they are wet. To minimize the discomfort caused by wet adhesion, less hydrophilic fabric surfaces may be preferred. [ABSTRACT FROM AUTHOR]

Introduction The aim of this study was to investigate the sterilization potential of atmospheric pressure plasma jet (APPJ) and interactions of this technology with double-stranded DNA using the polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) techniques. Materials and Methods The plasma jet was produced through a high voltage sinusoidal power supply using a mixture of argon and oxygen gases with the flow rate of 1 L/min. Escherichia coli cells and double-stranded DNA (dsDNA) fragments were amplified by T7 universal primer through the PCR technique and treated with argon/oxygen APPJ at different exposure times. The data were analyzed by the agarose and polyacrylamide gel electrophoresis, SSCP and renewed PCR techniques. Results According to the results of the study, the APPJ could serve as an effective instrument for sterilization at > 30 sec discharge. The destruction of DNA was detectable by different techniques after 120 sec from APPJ discharge. Conclusion Our findings revealed that the active species of plasma can lead to cell death. These species may break or nick the dsDNA, exchange DNA nucleotides, and lead to transition and transversion mutations. These mutagenesis effects of APPJ might be the reason of microorganism cell death after the treatment in addition to other destructive effects of APPJ on macromolecules. [ABSTRACT FROM AUTHOR]

Deposition of plasma polymers using atmospheric pressure plasma jet in mixture of argon, air and hexamethyldisilazane (HMDSN) was studied. The HMDSN monomer, used as film precursor, was carried to the jet nozzle by an auxiliary airflow and mixed with principal argon flow. The films were deposited for different times using mean discharge power of 2.8 W, main argon flow of 1 SLM while the carrier flow (air + HMDSN) was 0.1 SLM. The water contact angles measured across the obtained HMDSN plasma polymer film showed two well-defined areas, one hydrophilic, with contact angle near zero degrees and one hydrophobic, with contact angle around 100 degrees. The FTIR spectra showed that part of the original structure of HMDSN monomer was preserved and new chemical bonds were observed. XPS analysis showed that the deposited coatings are inorganic SiO 2 -like coatings. The films thickness was evaluated and it reached values about 2 μm in the center and decreased to the border (in continuous deposition mode more rapidly than in the pulsed one). Roughness values were obtained and it is shown that they varied for each region of the film. [ABSTRACT FROM AUTHOR]

This work deals with surface modification of aluminium alloy AA7075 by two types of atmospheric pressure plasma: dielectric barrier discharge (DBD) and atmospheric pressure plasma jet (APPJ) with the purpose to enhance the adhesion of polyurethane coating on the alloy. The surface characterization was performed by using water contact angle, roughness and surface free energy measurements. Quality of the coating was tested according to the adhesion tape test (ASTM D3359) and evaluated by electrochemical techniques. The aluminium alloy showed great improvement of the surface wettability after plasma treatments. While, the adhesion tape test presented excellent results with perfect adhesion, meaning that both plasma treatments were efficient in improving the adhesion of the polyurethane coating to the AA7075. The Fourier Transform Infrared Spectroscopy (FTIR) results demonstrated that the plasma treatment cleaned the Al alloy surface by removing hydrocarbon contaminations. Both polarization curves and Electrochemical Impedance Spectroscopy (EIS) results showed better characteristics of corrosion resistance for polyurethane-coated AA7075 than untreated coated samples. [ABSTRACT FROM AUTHOR]

The friction between glass and elastomeric parts in vehicles can cause problems like uncomfortable noises, vibrations and damage to the sliding surfaces that have a negative impact on the quality of the product. These problems are usually addressed by modifying the elastomeric surfaces in order to reduce friction. However, the recent development of atmospheric-pressure plasma technologies offers new alternatives for surface treatment and coating deposition in large areas. Therefore, this work attempts to reduce friction by the deposition of SiO x -based coatings on glass substrates in an atmospheric-pressure plasma jet (APPJ) system, using aminopropyltriethoxysilane (APTES) as precursor. Different numbers of passes and plasma powers were used in the deposition process to identify the influence of these parameters on the growth, morphology, chemistry and tribological behavior of the coatings. These characteristics were studied by Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), tribological tests, profilometry, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX). The thickness and chemical composition of the coatings appear to determine their tribological behavior. The reason is that sufficient inorganic character and thickness seem to be necessary to effectively reduce the friction coefficient of glass. The coating that was obtained with the greatest number of passes and plasma power used in this work (i.e., 18 passes and 550 W) exhibited the best tribological behavior. This coating achieved a reduction of 86% in the friction coefficient of the uncoated glass without significantly impairing its wear resistance. The results of this research suggest that the APPJ systems provide a promising technology to reduce the friction of glass surfaces. This technology also can be attractive for glass that is used in solar panels and architectural applications. [ABSTRACT FROM AUTHOR]

In this paper, we want to develop and characterize a round argon-based nonthermal atmospheric-pressure plasma jet (APPJ) with an application of sterilization. We measured the basic properties of APPJ by an alcohol thermometer, an optical emission spectrometer (OES), a high-voltage probe and a Rogowski coil. The plasma jet temperature at the tube exit is lower than 37 °C, which will not induce damage to living tissue. The plasma absorbed power is about 2.7 W. The OES data indicate that this APPJ has a relatively high intensity of hydroxyl radicals (OH) in postdischarge region. Furthermore, we applied this device to inactivate the bacteria (E. coli and B. subtilis) and endospore (B. subtilis endospore). In addition, the trace amount of oxygen addition (0.04%) into working gas can not only enhance the OH radicals but also speed up the killing of bacteria and endospore. The results of D value and scanning electron microscope images show its great potential for the use of general sterilization in the future. [ABSTRACT FROM PUBLISHER]

In this paper, the partial modification of the biaxially oriented polypropylene (BOPP) film for potential biological and packaging applications was achieved via hydrophilic modification using atmospheric pressure plasma jet (APPJ). In the APPJ system, the allylamine (ALA) monomer was polymerized on the BOPP surface by either the Ar/O 2 or the He/O 2 plasma. The results showed that plasmatic modification created many micro/nano sized holes on the BOPP film, which increased the surface roughness dramatically and the increased roughness enhanced the combining intensity between the BOPP film and the ALA polymer. However, such a plasmatic modification increased the water vapor permeability. The FTIR and XPS characterizations showed that the amine groups were grafted onto the BOPP film, and the contact angle of the BOPP film decreases from 98.5° to 8°. Compared with the BOPP films treated by the Ar or He plasma, the barrier property of the modified BOPP film increased significantly when the ALA polymer was incorporated. The bio-affinity/toxicity of ALA polymer was illustrated by the attachment of the cultured SMMC-7721 hepatoma cells on the modified BOPP film. The significant enhancement in the cell density indicated that modified BOPP film was highly bio-compatible and non-toxic, especially treated with the Ar/O 2 /ALA plasma. [ABSTRACT FROM AUTHOR]

The aim of this study is to deposit a superhydrophobic film on the cylindrical ceramic surface with APPJ. The influences of treatment parameters such as treatment duration, distance, and rotation speed, on the film hydrophobicity, are investigated. The results for static treatment show that a superhydrophobic organosilicon film is deposited on the central region of the ceramic surface at optimal treatment distance and treatment duration of over 2 min. The film hydrophobicity is constricted by short or long treatment distances due to insufficient film deposition to form micro-nano mountainous structures covering the original crystal structures of the ceramic surface. Moreover, the water contact angle distribution is discovered to present as layering ellipses, and its mechanism is explored based on the interactions between the cylindrical material and APPJ. Dynamic treatment is performed, and a uniform superhydrophobic film six times longer than the plasma plume diameter is obtained within the rotation speed of 120 r/min. Results in this paper serve as guidance for the application of plasma jets in film deposition on non-planar material surfaces. [Display omitted] • The film hydrophobicity presents elliptical layering for static treatment. • A layering mechanism is proposed for cylindrical surface film deposition with APPJ. • The layering film properties can be tailored by regulating the treatment distance. • A uniform superhydrophobic organosilicon film is deposited on cylindrical ceramic. • The superhydrophobic film length is several times larger than the plume diameter. [ABSTRACT FROM AUTHOR]

To obtain uniform and bead-free nanofibers by means of electrospinning is sometimes very challenging, especially for polymers with low solubility, such as for example the intrinsically conducting polymers (ICPs). Recently, atmospheric pressure plasma jet (APPJ) treatment to pre-electrospinning polymer solutions has been found to effectively enhance the electrospinnability of a single polymer type. Here, such an APPJ treatment has been applied for the first time to a blended polymeric solution consisting of polylactic acid (PLA) and polyaniline emeraldine base (PAni EB) as well as its emeraldine salt (ES) form doped by camphorsulfonic acid (CSA). The plasma-induced physical changes of the solutions including pH, conductivity, viscosity and surface tension have been investigated and correlated with the ensuing physicochemical properties of the electrospun nanofibers. To do so, next to the liquid-based characterizations, the nanofibers have been examined by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), water contact angle (WCA) goniometry and uniaxial tensile testing. Results revealed that the pre-electrospinning plasma modification step resulted in a remarkably enhanced nanofiber morphology, deposition yield and mechanical performance of the electrospun nanofibers. Moreover, concomitant doping of PAni EB to PAni ES, as an unexpected side behaviour generated during the plasma treatment without the addition of any protonic acid, was found and further carefully investigated using ultraviolet/visible (UV–Vis) spectrometry. The findings obtained in this work thus enlarge the application range of pre-electrospinning APPJ treatment from single to blended polymeric solutions. Moreover, the recent pioneering discovery revealing the pre-electrospinning APPJ treatment role in enhancing electrospinning has surpassed the sole connotation of improved fiber morphology as new interesting effects are discerned in this study: boosted nanofiber deposition yield and doping capabilities. [Display omitted] • APPJ treatment has been applied for the first time to a blended polymeric solution system. • The improved deposition yield is revealed for the first time as an important positive effect of APPJ treatment. • Concomitant doping of PAni EB is found as an unexpected side behaviour generated during the APPJ treatment. [ABSTRACT FROM AUTHOR]

The effect of atmospheric pressure plasma treatment on the adhesion between a protective coating and AA1100 alloy was investigated. Two plasma sources were used for surface modifications: atmospheric pressure plasma jet and dielectric barrier discharge. The surface roughness and water contact angle measurements were conducted in order to evaluate the changes on the aluminium surface after plasma processing. The paint coating was tested using the adhesion tape test (ASTM D3359). A significant improvement of surface wettability and adhesion was obtained after plasma treatments. [ABSTRACT FROM AUTHOR]

Eu:GdVO 4 nanophosphors with an average size of 60 nm, synthesized by a facile solvothermal method, were deposited on monocrystalline silicon wafers by a spray-coating technique with artworks anti-counterfeiting applications in mind. Atmospheric pressure plasma jet (APPJ) was used to deposit a silica-based layer on top of the nanometric luminescent layer, in order to improve its adhesion to the substrate and to protect it from the environment. The nanophosphors were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Coating composition was investigated by Fourier transform infrared spectroscopy (FT-IR) and its morphology was characterized by scanning electron microscopy (FEG-SEM). The film thickness was evaluated by means of ellipsometry and adhesion was estimated by a peeling test. Luminescent properties of the nanophosphors deposited and fixed on silicon wafers were also measured. The whole layer resulted well-adhered to the silicon substrate, transparent and undetectable in the presence of visible light, but easily activated by UV light source. [ABSTRACT FROM AUTHOR]

The study reports unique aspects of oxidative and nitrosative environment and generation of radicals in a newly developed 13.56 MHz cold atmospheric pressure plasma jet (APPJ) device using optical emission spectroscopy (OES). Signature of generated species, species density, energy, their spatial variation and interaction with liquid medium are investigated. While techniques to achieve controlled generation of atomic oxygen and nitrogen in the same device are identified, distinct ability of pure argon APPJ to break oxygen molecules in air releasing atomic oxygen is an interesting finding. Boltzmann plot technique is used to determine the electron excitation temperature. Time averaged gas temperature is measured using mercury thermometer as well as matching simulated and experimental spectra of A-X band of OH radical. Electron density is determined from spectral broadening of H α line. Formation of OH radical is detected via its signature A-X band. Measured electron density and electron excitation temperature are of the order of 1021 per m3, and 3 eV respectively at the nozzle exit. Standard test strips are used to investigate generation of H 2 O 2 , NO 2 and NO 3 radicals through interaction of the plasma jet with water as a function of time. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, deposition of transparent and conductive ZnO thin films using an atmospheric pressure plasma jet (APPJ) is presented. The APPJ is sustained by a pulsed power source with a repetitive frequency up to 25 kHz using N 2 as the plasma gas. ZnCl 2 solution is used as the precursor and is nebulized and then sprayed into the downstream of the APPJ. With sufficiently long retention time and high jet temperature, a nearly full conversion of the precursor to ZnO occurs. Zinc hydroxyl chloride, with sheet-like structures, is formed as the intermediate when the precursor is not fully converted to ZnO. With an optimal condition, ZnO films with a resistivity of 1.4 Ω-cm and average transmittance between 400 and 800 nm of greater than 80% can be obtained with the root-mean-square surface roughness approximately 10 nm. This demonstrates a one-step and fast process without the need of post-annealing steps and intentionally doping to fabricate transparent and conductive ZnO films. [ABSTRACT FROM AUTHOR]

In this paper, the effect of surface treatments carried out with an atmospheric pressure plasma jet, generated by air, on the passive film of AA1071 and AA2024 was investigated. The samples of the aluminium alloys, before and after the surface plasma treatments, were analysed by secondary ions mass spectrometry depth profiling and by X-ray photoelectron spectroscopy. Potentiodynamic anodic polarisation tests and electrochemical impedance spectroscopy measurements were carried out to study the influence of the surface plasma treatments on the corrosion resistance properties of the Al alloys. The plasma treatments induced the oxidation of the surface and the formation of a thicker and denser passive layer, which exhibited higher corrosion resistance than the native film. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a two-step process was explored for the modification of poly(ethylene terephthalate) (PET) fabrics by Ar/O2 plasma-induced polymerization with hexamethylene diamine (HMD) monomer. The first step involved a parallel-plate shape dielectric barrier discharge (DBD) apparatus to modify the PET fabrics. This treatment could introduce some polar groups onto the PET surface, and also simultaneously increased the surface roughness. Thus, this process was very helpful to increase the linking intensity between the fabric substrate and the later polymerized layer. For the second step of the process, an atmospheric pressure plasma jet (APPJ) apparatus with Ar and O2 as working gases was employed to achieve the polymerization with HMD monomer on the fabric surface. The measurement of the plasma gas temperature by infrared thermometry, and the detection of reactive species by optical emission spectroscopy were used for characterizing the polymerization process. It was found that the plasma gas temperature was not higher than 307K when the applied power was lower than 50W, and many reactive species (e.g. •OH, •H, •O) existed in the plasma. Field emission scanning electron microscopy images showed that the surface roughness of PET increased greatly with the DBD plasma treatment, and a smooth thin film was formed under the APPJ polymerization with HMD monomer. Fourier transform infrared spectroscopy results indicated that HMD polymer was incorporated into PET fabrics through the formation of new covalent bonds. Chemical composition was analyzed by X-ray photoelectron spectroscopy, and many functional groups (e.g. C–N, O=C–NH) occurred on the PET fabric surface. Meanwhile, the dyeing property of modified PET evaluated by color yield (K/S) analysis was improved obviously. [Copyright &y& Elsevier]

Abstract: In order to improve the interfacial adhesion property between PBO fiber and epoxy, the surface modification effects of PBO fiber treated by atmospheric pressure plasma jet (APPJ) in different time, atmosphere and moisture regain (MR) were investigated. The fiber surface morphology, functional groups, surface wettability for control and plasma treated samples were analyzed by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements, respectively. Meanwhile, the fiber interfacial shear strength (IFSS), representing adhesion property in epoxy, was tested using micro-bond pull-out test, and single fiber tensile strength was also tested to evaluate the mechanical performance loss of fibers caused by plasma treatment. The results indicated that the fiber surface was etched during the plasma treatments, the fiber surface wettability and the IFSS between fiber and epoxy had much improvement due to the increasing of surface energy after plasma treatment, the contact angle decreased with the treatment time increasing, and the IFSS was improved by about 130%. The processing atmosphere could influence IFSS significantly, and moisture regains (MR) of fibers also played a positive role on improving IFSS but not so markedly. XPS analysis showed that the oxygen content on fiber surface increased after treatment, and Clyph name="sbnd" />Cwere introduced on fiber surface. On the other hand, the observed loss of fiber tensile strength caused by plasma treatment was not so remarkable to affect the overall performance of composite materials. [Copyright &y& Elsevier]

Abstract: An atmospheric pressure plasma jet (APPJ) for continuous treatment of polymeric films and textile materials was investigated to characterize its thermal, hydrodynamic and chemical features. The operative variables of the plasma jet equipment are: gas flow rate and composition, electrical power to the plasma generator and fabric velocity. A diagnostic evaluation of the equipment was carried out to improve the treatment homogeneity and generate an effective feedback for scale-up. The cross profile of gas temperature and velocity, the fabric temperature and concentration transitory in the gas system generated by a reverse step of oxygen were determined. These measurements showed that the original prototype configuration required a better gas distribution to fully demonstrate its potentiality to functionalize textiles. The surface modifications induced by plasma were detected by processing wool fabrics and by evaluating the treatment benefit on dyeing. [Copyright &y& Elsevier]

Abstract: The aim of this work is to study the thermal characteristics and electron density based on atomic and molecular emission of a new plasma jet at atmospheric pressure. The novelty of our jet is its generation with a single electrode, the plasma gas flowing perpendicularly to the RF powered electrode (13.56MHz, 103 V). Optical emission of the plasma was collected in two ways: the normal viewing mode and the axial viewing mode. The plasma characteristic parameters as function of helium flow-rate, plasma power and position of the investigated zone were studied. The excitation, vibrational and rotational temperatures are in the range of 1500–2350K, 3500–4400K and 450–1100K, respectively. The electron number densities are in the range of 1013–1014 cm−3. For qualitative observations regarding the atomic and molecular processes in the plasma we used the relative intensities of the most representative lines of He, N2, O, H and . [Copyright &y& Elsevier]

Abstract: We have constructed a large area atmospheric pressure plasma jet (LAAPPJ) composed of two planar electrodes with an area 38cm2 at a distance of 2.5mm.The LAAPPJ was operated with helium at a gas flow rate of 1.5mmol/s. The electrical properties of the discharge were studied by measuring the voltage and the discharge current simultaneously using a high voltage probe, a current probe and a digital oscilloscope. Pictures of the discharge were taken with a digital camera. Two discharge modes can be sustained within certain limits. At RF input powers of 50–420W an α-discharge can be sustained, however, below approximately 300W the electrodes are only partially covered with the glow. At higher powers a breakdown occurs and a transition to a γ-discharge takes place, whereby the α-discharge dies out. The γ-discharge only covers a part of the electrodes and can be sustained down to powers of 50W. Below this power the discharge extinguishes. [Copyright &y& Elsevier]

Amorphous indium–gallium–zinc‐oxide thin‐film transistors (a‐IGZO‐TFTs) with the LaAlO3/ZrO2 gate dielectric stack employing a novel atmospheric pressure plasma jet process that results in small subthreshold swing and low threshold voltage are proposed and fabricated. The influence of post‐deposition annealing (PDA) temperature on LaAlO3/ZrO2 gate dielectric stack and device performance was investigated. The equivalent oxide thickness of the LaAlO3/ZrO2 dielectric stack decreases from 11.5 nm without annealing to 7 nm after a 500°C annealing was applied. The LaAlO3/ZrO2/a‐InGaZnO TFT with a 500°C annealing exhibits a small subthreshold swing of 77 mV·dec−1, a high field‐effect mobility of 9 cm2·V−1·s−1 and an excellent current ratio of 1.8 × 107, which could be attributed to the improved gate dielectric quality by the PDA. The LaAlO3/ZrO2/a‐InGaZnO TFTs with excellent gate control ability allow the device to operate at a low operating voltage with low power consumption. [ABSTRACT FROM AUTHOR]

This work demonstrates the influence of shielding gases on the performance of an atmospheric pressure plasma jet (APPJ) and its efficiency in polyethylene terephthalate (PET) surface treatment. The impact of the shielding gas type (argon, nitrogen) and its flow rate on the spatial distribution of the reactive plasma species is determined by applying optical emission spectroscopy (OES) while surface analysis techniques reveal the influence of the plasma footprint on the polymeric surface under the same conditions. The findings indicate that the optical emission intensity of the reactive species is highly influenced by the shielding gas injection. Moreover, adding argon to the ambient atmosphere of the plasma jet during the treatment improves the PET degree of wettability and the size of the modified area. This outcome is supported by an increase in the amount of incorporated oxygen through increments in C–O and O–C O groups. Compared to argon, nitrogen shielding gas decreases the area of the plasma impact and acts as a barrier for activating the surface. These results thus reveal the potency of shielding gases on controlling the APPJ ambient conditions and its surface modification effectiveness. Image 1 • A higher amount of plasma excited species is detected for argon shield gas. • Nitrogen shield gas reduces the number of plasma reactive species in the effluent. • Plasma jet with argon shield gas improves the polymer surface hydrophilicity. • Nitrogen shield gas acts as a hindrance for activating the polymeric surface. • Induced surface hydrophilicity correlates with introduced oxygen functionalities. [ABSTRACT FROM AUTHOR]

Adhesion is a key parameter in studying films and coatings. There are several techniques used to evaluate a film or coating, but the main procedures are indicated by ASTM D4541-17/D7234-12, ISO 4624:2016/16276–1:2007, and ASTM D3359-17 norms. These norms are semi-quantitative and in this study, image analysis with digital optical microscopy shows a quantitative evaluation for each of them. Also, due to the low surface energy and limited adhesion properties of polymeric materials, this study was carried out on the modification of the surface of a polymeric substrate (polycarbonate) by using the treatment of flame and atmospheric pressure plasma to improve the interfacial adhesion between substrate and coating. Various characterization techniques such as XPS, contact angle, Pull-off, Scotch tape, and digital microscopy have been used to determine the adhesion and surface characteristics. The applied treatments are used to chemically modify the surface, thus, obtaining surfaces with hydrophilic properties in line with the results obtained using contact angle, when compared to non-treated surfaces, so that an improvement in adhesion was obtained, being less than the area of detachment of the coatings. [ABSTRACT FROM AUTHOR]