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Despite advances in therapy, malignant melanoma remains a fatal disease. Among several emerging approaches to combat cancer, cold atmospheric pressure plasma (CAP) has shown promising results as a novel antitumor agent in preclinical models so far. The technology mainly relies on the emittance of various reactive oxygen and nitrogen species (ROS/RNS) that are tumor-toxic at high concentrations. Moreover, malignant melanoma has a metabolic dimension that can be targeted by mild starvation. To this end, we investigated the combined effect of starvation and CAP treatment on melanoma in vitro and in vivo. In vitro, starvation+CAP led to cell morphology changes, decreased metabolic activity and increased lipid peroxidation accompanied by apoptosis and DNA fragmentation in murine B16 melanoma cells but not murine non-malignant L929 fibroblasts. This was paralleled by increased apoptosis (Bax, Bcl-2 and Caspase-3) and autophagy (Lc3 and Atg5)-related gene expression. In vivo, starvation reduced tumor burden. Combination with CAP treatment augmented this effect significantly, albeit there was no difference of combination treatment to CAP exposure alone. Interestingly, there was an overall greater increase of Lc3 and Atg5 in the tumor tissue compared to CAP exposure alone, while starvation-induced autophagy-related gene expression was similar to in the combination group. These data collectively suggest that CAP-derived ROS/RNS treatment and autophagy-induction augment antitumor effects in malignant melanoma in vitro and in vivo.

In this research, the effects of cold plasma treatment on the properties of gelatin‐based emulsion films (GEFs) using different gases were investigated. The gases used include O2, N2, air, Ar, and ethanol‐argon (EtOH‐Ar). Surface hydrophobicity, morphology, water vapor permeability (WVP), and mechanical, thermal, and antifungal properties after plasma application on the film were analyzed. The results revealed that surface hydrophilicity significantly increased after cold plasma, while the contact angle significantly decreased (p .05). Oxygen permeability after plasma application was significantly different from the control sample; consequently, the permeability after plasma application decreased and the lowest level 55.7 (cm3μm m−2 day−1 Pa−1) was seen for oxygen gas. Plasma treatment caused etching effects and lessened the surface moisture of the polymer film. Antimicrobial activity was observed in the cold plasma‐treated samples, especially under air and nitrogen atmosphere. Cold plasma treatment is an effective method for surface modification, expanding the application of emulsion films in the packing industry with improved performance properties., The effects of cold plasma treatment on the properties of the gelatin‐based emulsion films (GEFs) using different gases including O2, N2, air, Ar, and ethanol‐argon (EtOH‐Ar) were studied via analyzing surface hydrophobicity, morphology, water vapor permeability (WVP), and mechanical, thermal, and antifungal properties.

The relativistic mirror (RM) is an interesting subject which introduced in the nonlinear regime of the laser–plasma interaction. Reflection of counter-propagating probe pulse from relativistic flying mirror has some excellent features, such as frequency up-shifting and compressing by a factor of 4γ2. In the high-intensity laser–plasma interaction, sometimes a sequence of RMs creates. For example, electron density cusps generate in the nonlinear laser wakefield generation or flying electron sheaths create in the blown-out regime of the laser foil interaction. Under these circumstances, the second counter-propagated seed (probe) pulse can be reflected back and forth between two or more successive RMs. This structure may be used as a relativistic cavity (RECA). Amplification and threshold conditions for the gain medium and pumping rate in the RECA are obtained, and it is shown that amplification can be started from background simultaneous emission (without seed pulse). A new feature of RECA is it's bidirectional (two frequencies) characteristic. Thereupon, the gain process can be implemented on the two different transitions in this bidirectional gain structure. In the RECA, driver pulse may be assembled as a pumping operation, and background plasma medium with high degree ionized substances is a good candidate for gain medium in the UV or X-ray regions. In this paper, we propose a new all-optical cavity for the generation of the ultrashort laser pulse in the UV or X-ray regions.

In this work, we studied hollow cylindrical plasma bullets propagating along the grooved glass rod in a single electrode configuration. The plasma source was a cylindrical shell consisted of two coaxial glass cylinders. The surface of the inner cylinder was structured by creating grooves on its surface to investigate the plasma bullet acceleration through the traveling shell. The corresponding plasma jet was driven by a 6.2-kHz sinusoidal waveform using helium gas. Optical and electrical characteristics proved that the plasma jet was working in a stable bullet mode. The propagation speed of the hollow cylindrical bullet was evaluated along with the downstream of the jet axis inside and outside of the plasma carrier shell. The results showed that the charge associated with the bullets and corresponding root-mean-square (rms) value of the alternative current (ac) electric field were increased by creating the grooves on the path of the bullets. It was observed that the radiation intensity of the plasma was increased around each groove, too. The structured inner cylinder revealed that the dielectric properties play an essential rule in the plasma bullet propagation through tubes.

Pseudomonas aeruginosa is a multidrug-resistant bacterial strain with the ability to produce exotoxin A which can pose a serious threat to freshwater ecosystems by having pathogenicity against eukaryotes. Detoxification of exotoxin A and disinfection of P. aeruginosa are the main aims of this study. Using a high dosage of antibiotics might have more toxic effects on ecosystems while cold atmospheric plasma (CAP) can promise reliable, rapid, and environmentally friendly detoxification and disinfection. In this study we produced CAP reinforced by H2O2/H2O cold vapor to detoxify exotoxin A and inactivate P. aeruginosa in freshwater. We used Gammarus roeseli as the indicator of ecotoxicity in freshwater. The mortality of G. roeseli individuals elucidated that 420 s of CAP treatment under a surface dielectric barrier discharge (SDBD) set up can effectively passivize exotoxin A in freshwater by disrupting the protein structure of molecules. Ignorable side effects and changes to the physiochemical properties were observed. On the other hand, 8.2 log reduction of P. aeruginosa viable cells was observed after 300 s of treatment by SDBD. A comparison between the disinfection capacities of SDBD produced CAP and antibiotics revealed that CAP is more effective than most of the common antibiotic agents.

Many studies in the field of cold plasma and its application in medicine and biology have been done recently. Some of them reported that cold atmospheric pressure plasma jet (APPJ) discharge accelerates blood clotting because factor VIII (FVIII) is a plasma glycoprotein that may play a role in the coagulation cascade. In this study, we aim to assess the effect of APPJ discharge on factor VIII antigen (FVIII:Ag) in healthy and hemophilic patients. Therefore, the variations of FVIII:Ag in healthy plasma samples and hemophilic plasma samples at the times of 0, 4, 8 and 16 s treatment with APPJ were measured by ELISA technique. Additionally, activated partial thromboplastin time (APTT) test was used to check the blood coagulation rate at different treatment times. Our findings showed that the amount of FVIII:Ag in healthy samples was high to low in seconds 4 > 8 > 16 > 0. The APTT results showed that APPJ increases the blood clot formation, but in hemophilic plasma samples, APPJ reduces the clot formation speed and FVIII:Ag concentration. Accordingly, the APPJ discharge elicited a slight increase in FVIII:Ag concentration in short-term treatment, which could be involved in blood coagulation. Moreover, the effects of APPJ discharge on other coagulation factors need further studies.

In this study, we developed a new cold dielectric barrier discharge (DBD) apparatus comprising two covered flat electrodes and an array of bared spinal needles aiming for large scale treatment processes. The favored cold atmospheric pressure plasma was produced using Ar gas and n-hexane vapor for hydrophobic deposition on cotton fabric. It was shown that installing the third electrode is crucial in this configuration for producing hydrophobic deposition on cotton fabric. Formation of diamond-like carbon (DLC) deposition was confirmed by experimental analysis. Our samples were analyzed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The presence of sp3 C H bonds was observed from ATR-FTIR analysis. Diesel oil/water separation experiments were performed to show the effectiveness of the treated cotton in the filtering of oil from water. The static water contact angle (WCA) measurements showed an excellent super-hydrophobicity of cotton fabric with WCA higher than 1500 (Ө = 159.590) and sliding angle of ~40. Additionally, aging experiments proved that the treated samples maintained superhydrophobic properties even after multiple washing.

In the present research, the performance of the electrohydrodynamic force in an asymmetric surface dielectric barrier discharge actuator has been investigated at different bias voltages. The effects of DC, AC plus DC (DC-offset), and sinusoidal bias voltages on the force generation have been studied through measuring the electric wind velocity profiles, surface potential, and electric field. The results showed that applying DC and DC-offset biases to the lower electrode instead of connecting it to the ground in a typical case increased the charge deposition on the dielectric surface and consequently reduced the electrohydrodynamic force generation. This effect was also observed in case of exchanging these voltages with AC sinusoidal voltage of the upper electrode. In addition, as a new idea, two-phase shifted AC voltage was applied to the electrodes and the resulting changes have been studied. The obtained results at 180∘documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$180^{^circ }$$end{document} phase difference were very noticeable and showed 46% improvement in the maximum velocity of the induced flow relative to the grounded electrode with the same input power. Using this technique, a certain wind velocity can be obtained at relatively lower voltages and input powers compared to the conventional case of grounding the lower electrode. Such a capability is significant in aerodynamic applications, where applying large values of the high voltages may disturb the operational systems.

www.springerlink.com; International audience; We report a method to obtain biocompatible PEG copolymer coatings inside High Density Polyethylene (HDPE) and Pyrex tubes, which was successfully developed by using a transporting discharge. The latter being a dry process, it is easier to apply as compared to the conventional multistep wet chemical techniques. The results presented in this paper show that for a 70 cm tube good cell repellent properties as compared to the control was obtained for the entire length of the tube. The best nonfouling properties with respect to CT-26 (colon cancer) were obtained for coatings presenting the best retention of ether functionalities from the DEGME monomer i.e. between 5-25 cm downstream of the tube. These results are interesting for surface modification of biomaterial and biomedical devices which present hollow bodies.

The cold atmospheric pressure plasma jet (APPJ) is one of the effective tools with medical applications that its positive effects have been reported by various researchers, including sterilization of liquid and solid surfaces, treatment of chronic wounds, treatment of cancer tumors, and blood clots. This study investigated the effects of APPJ discharge on the two species of Earthworms (Aporrectodea trapezoides and Eisenia fetida). The APPJ discharge for different time durations, zero as a blank, 5, 10, 20, and 30 seconds, on these two species. Then some of these effects on the worms, including regeneration ability to miss segments, Malondialdehyde (MDA), catalase activity (CAT), total antioxidant capacity (TAC), cell death, total proteins, and protein profile in the coelomic fluid were investigated. Results showed levels of TAC and CAT increased after plasma treatment. In addition, a significant change was not observed in MDA levels and cell death. In summary, it can be concluded that APPJ exposure up to 40 seconds didn’t inhibit effects on the TAC levels of the earthworms and the defense system was able to fight oxidative stress and by increasing the expression of some proteins APPJ lead to better regeneration.

Enterococcus faecalis is a life-threatening bacterium that resists high levels of antibiotics or chemical preservatives. In this study, we aimed to investigate the inactivation of E. faecalis in fresh pineapple juice (FPJ) with two different cold atmospheric plasmas (CAP) reinforced by H2O2/H2O cold vapor: a plasma jet and a surface dielectric barrier discharge (SDBD). CAP treatments for 300 s with plasma jet and 420 s with SDBD caused an 8.2 log reduction of E. faecalis. The concentration of reactive oxygen and nitrogen species induced in FPJ by plasmas was also evaluated. In terms of quality attributes of FPJ, no noticeable color changes (ΔE) were observed. Furthermore, a trifle of loss of organic content such as sugars and organic acids was observed after treatments. These results suggest that our rapid CAP strategy effectively inactivated E. faecalis in FPJ with no change of color and negligible effects on other physicochemical properties.

In this study, two-dimensional simulation of the microplasma field-effect transistor (MOPFET) was performed using COMSOL Multiphysics along with BOLSIG $$+$$ software and LXCat database. At first, argon plasma generation in the electric discharge channel was investigated in the case of an RF-biased drain terminal. The Townsend criterion for self-sustaining discharge was modified by including ion-enhanced secondary ionisation concerning to the micrometer scale of the discharge gap. The simulation results showed that the level of the gate electrode voltage serves as a tuner for the MOPFET current, and it changes the gas breakdown voltage. The results of the 2D simulation showed that the polarity of the gate voltage is crucial for controlling the MOPFET current and the operation of switching circuitry. To increase current, a new gas mixture was proposed and simulated. The $$I_{\mathrm {DS}}{-}V_{\mathrm {DS}}$$ characteristic of the MOPFET was obtained with Ar/Hg (98:2). Static transconductance and $$h_{\mathrm {FE}}$$ of the MOPFET were also evaluated. The results of this study can be used for designing and operating the MOPFET in an electronic circuit.

In this study, an argon plasma jet was made for therapeutic purposes. Although cold plasma jet (CAPJ) is considered a safe device, its risk assessment is essential to be approved for a clinical trial. To this end, the safety parameters of the CAPJ were evaluated from both aspects associated with the instrument such as design, construction, and environmental conditions, and also function on living organisms. It was shown that the device is physically safe for the user and the animal. In continue, healthy rats were treated by the plasma at two modes of streamer and plume mode at two distances of 20 and 25 mm from the nozzle for 2, 5, and 10 minutes of exposure time. In the study of blood serum biochemistry, the strongest deviation from the average is observed at alkaline phosphatase in the plume mode in the 10min (P10) group. Also, the amount of Aspartate transaminase (AST) in the blood serum of rats is lower than the control group for all groups except streamer mode at 10 min exposure (S10). And, the mean ALT enzyme in the serum of the S5 group is significantly higher compared to the plume mode in the 5 min (P5) group. The histopathology of the liver is studied to support these results. Shrinkage of the nucleus, cell swelling, and hyperemia are observed in the liver tissue for streamer mode, while in the plasma plume mode, these changes are not tangible. No significant difference is observed in the mean value of total Bilirubin, Direct Bilirubin, Albumin, Na, and K factors in the different groups after the plasma treatment and the histopathology of kidney tissue is performed for all the groups to support this conclusion and it did not show any damage to the kidney tissue. As a result of risk assessment in this study, the treatment with a duration of 2 to 5 minutes is safe with the specifically designed CAPJ nozzle head at a distance of 25 mm from the nozzle.

Cervical cancer is one of the important cancers in women. Research on novel treatment approach can reduce the mortality and burden. Although radiotherapy is a common treatment, its negative side effects have concerned physician. In our study, we studied impact of cold atmospheric pressure plasma on the Hela cancer cells, as an alternative treatment. The effect of three different types of such plasma; dielectric barrier discharge (DBD), plasma jet, and afterglow plasma, on the cancer cells were studied. Moreover, some effective operating parameters such as exposure time, applied voltage, composition of working gas in plasma treatment were investigated on the survival of the afterglow plasma. Finally, treatments by the afterglow plasma, gamma radiation (1 Gy), and combination of both were compared. Analysis showed that DBD and plasma jet (direct exposure) effectively killed the cancer cells, even by a minimum applied voltage. But a fraction of the cells survived after the exposure of indirect diffused afterglow plasma. In the case of this plasma, we realized that higher applied voltage and exposure time led to less cell viability. Fewer fractions of survival cells were detected in the case of argon afterglow plasma comparing to oxygen afterglow. Cold atmospheric plasma and its combination with radiation therapy showed a significant decrease in viability of the cells, comparing to the radiation alone. Our research showed that plasma and its combination with radiation therapy have superiority over radiation therapy.

Malignant melanoma is a devastating disease. Because of its aggressiveness, it also serves as a model tumor for investigating novel therapeutic avenues. In recent years, scientific evidence has shown that cold atmospheric plasma (CAP) might be a promising modality in cancer therapy. In this study, we aimed to evaluate the effect of CAP generated by an argon plasma jet alone or in combination with dacarbazine (DAC) on melanoma cells in vitro and in vivo. The effects of the CAP on inducing lipid peroxidation and nitric oxide production were higher in B16 melanoma cells in comparison to non-malignant L929 cells. Assays on cell growth, apoptosis, and expression of genes related to, e.g., autophagic processes, showed CAP to have a substantial impact in melanoma cells while there were only minoreffects in L929 cells. In vivo, both CAP monotherapy and combination with DAC significantly decreased tumor growth. These results suggest that CAP not only selectively induces cell death in melanoma but also holds promises in combination with chemotherapy that might lead to improved tumor control.

In this study, the hydrophilic silk thread was changed to a hydrophobic surface by a compact cold atmospheric plasma (CAP) using Ar/C6H14 mixture as the working precursor. To test the hydrophobicity of the treated samples, water repellent examinations were performed and the static water contact angle of 139.62° was obtained. The durability of hydrophobicity was investigated using washing cycles and the aging effect. The color test of the samples was performed in CIELAB color space showing good stability in the silk color. To characterize the morphology of the processed samples, the changes in chemical bonds on the surface, deposited thin layer and redistribution of the atomic content on the surface were performed by atomic force microscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive spectroscopy and X-map analyses, respectively. The CAP key parameters were investigated by the voltage–current profiles and optical emission spectroscopy. Moreover, the mechanical properties of the processed silk threads such as breaking strength, elongation, and extension were found to be improved. The results of this work could be used in the textile factory to modify the silk threads before or after dyeing, as well as for other fibers like wool and polyesters.

In this study, we developed an apparatus by combining n-hexane electrospray and atmospheric pressure argon plasma jet for deposition diamond like carbon (DLC) layer as a hydrophobic film on cotton textile. n-Hexane was used as a hydrocarbon precursor for preparing ionized spray for atmospheric pressure plasma (APP) jet. In order to characterize the plasma, electrical measurement and optical emission spectroscopy (OES) were employed. The electron excitation temperature of the APP was estimated by Boltzmann plot method. Water contact angle (WCA) measurement was used to evaluate the hydrophobicity of the samples. The results showed that the water contact angle of these samples increases after treating by a combination of n-hexane electrospray and the APP jet. Considerations of aging effect on the samples clarified that the samples coated with longer times show better withstand against aging effect. Washing durability investigation of the samples showed that the hydrophobic property of the samples has acceptable durability in 50 washing cycles. Formation of diamond like carbon (DLC) coating on the substrates was proved by Raman and X-ray photoelectron spectroscopy (XPS) then characterized by FE-SEM analysis, energy dispersive spectroscopy (EDX) and X-Map probe. The results of this work were compared to the original one whose liquid precursor was ethanol. It was concluded that n-hexane precursor could result in better hydrophobicity comparing with that of ethanol precursor.

This work describes a theoretical study on shock wave modification by the electrical discharge generated with a DC voltage. Weakly ionized and high-density assumptions for nonthermal plasma were examined to demonstrate heat and momentum transfer contributions in supersonic flow control. The momentum equation for the plasma electrons and ions was considered to evaluate the changes in the incident flow velocity by the plasma. The change in the incident flow temperature was studied by applying source terms arising from a weakly ionized and high-density plasma to the energy equation. It was concluded that the momentum transfer from a nonthermal plasma into the incoming supersonic flow was responsible for the increasing shock wave angle. On the other hand, a nonthermal plasma with a remarkably high ionization degree increases the incident flow temperature drastically, while a weakly ionized plasma has a negligible effect on flow temperature. Our numerical results show that the electric field distribution has a significant role in the plasma flow control mechanisms, suggesting a new tailoring parameter via cathode geometry. The results of this work are in good agreement with respective experimental validation data and can be used in plasma-based shock wave control apparatus.

The results of time-dependent one-dimensional modelling of a dielectric barrier discharge (DBD) in a nitrogen–oxygen–water vapor mixture at atmospheric pressure are presented. The voltage–current characteristics curves and the production of active species are studied. The discharge is driven by a sinusoidal alternating high voltage–power supply at 30 kV with frequency of 27 kHz. The electrodes and the dielectric are assumed to be copper and quartz, respectively. The current discharge consists of an electrical breakdown that occurs in each half-period. A detailed description of the electron attachment and detachment processes, surface charge accumulation, charged species recombination, conversion of negative and positive ions, ion production and losses, excitations and dissociations of molecules are taken into account. Time-dependent one-dimensional electron density, electric field, electric potential, electron temperature, densities of reactive oxygen species (ROS) and reactive nitrogen species (RNS) such as: O, O−, O+, O2-documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ { ext{O}}_{2}^{ - } $$end{document}, O2+documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ { ext{O}}_{2}^{ + } $$end{document}, O3, N,N2+documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ { ext{N}}, { ext{N}}_{2}^{ + } $$end{document}, N2s and N2-documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ { ext{N}}_{2}^{ - } $$end{document} are simulated versus time across the gas gap. The results of this work could be used in plasma-based pollutant degradation devices.

This study aimed to investigate the inactivation of Pseudomonas tolaasii (P. tolaasii) strain Pt18 inoculated on button mushroom (Agaricus bisporus) by non-thermal plasma (NTP), using surface dielectric barrier discharge (SDBD). Furthermore, the effects of NTP on the postharvest preservation of Agaricus bisporus during 21 days of storage at 4 °C were studied. The so-called response surface methodology (RSM) was employed to investigate the efficacy of the plasma process parameters on bacterial inactivation and qualitative characteristics of Agaricus bisporus. The NTP at the optimum conditions of treatment time of 180 s and excitation frequencies of 6200 Hz under hydrogen peroxide vapor and air gas (H2O2+air) reduced P. tolaasii on Agaricus bisporus by 4.23 log CFU g−1 after 21 days of storage. The corresponding biological properties of NTP treated and control samples were also assessed. The results of firmness and moisture content suggested that plasma treatment could delay mushroom softening. In addition, vitamin C content of the treated button mushrooms increased despite observing insignificance (P > 0.05) in pH. Hydrogen peroxide vapor and argon gas (H2O2+Ar) treatment showed less Agaricus bisporus color changes during 21-day period. Therefore, it can be concluded that NTP as a novel technology has an excellent potential for improving the microbial contamination and enhancing qualitative properties of Agaricus bisporus.

In this study the applicability of cold plasma, produced by surface dielectric barrier discharge (SDBD), to inactivate Pseudomonas tolaasii (P.tolaasii), polyphenol oxidase (PPO) and peroxidase (POD) enzymes, as well as its impact on quality parameters such as, color, texture, pH and weight loss were evaluated. The study evidently shows that treating with combination of 30% hydrogen peroxide vapor)with flow rate of 0.47 mL min−1) and argon (H2O2 + Ar) for 180 s is capable of reducing the activity of PPO (0.17 U min−1 g−1 FW) and POD (0.21 U min−1 g−1 FW) and increasing the SOD enzyme (16.29 U g−1 FW) in a 21-day storage period compared to control samples. This is while the quality characteristics of button mushroom are preserved during storage after such treatment. Industrial relevance This study provides information of A. bisporus storage during 21-day period after SDBD plasma treatment, which is rarely. Greater inactivation of P. tolaasii after 180 s treatment with combination of hydrogen peroxide vapor and air (H2O2 + air) was shown compared to control samples, but this treatment caused also slightly degradation of button mushroom color. A better reduction of PPO and POD enzyme activity as well as further increase of SOD enzyme activity was observed following treatment with 180 s of H2O2 + Ar gas in a 21-day storage period. This research work contributes to the understanding SDBD plasma induced effects on the shelf-life of button mushroom and could be a basis for a possible industrial implementation.

The main focus of current research was on the effect of cold atmospheric-pressure plasma (CAP) on the rheological properties of gum Arabic (GA). GA powder was treated by dielectric barrier discharge (DBD) plasma with ambient air at different times (20, 40, and 60 min). The rheological properties of both natural and treated-gum dispersions were specified. The results showed the CAP treatment time had a notable and non-linear effect on the rheological parameters of the treated gums. Compared with control, all treated-gum dispersions showed higher apparent viscosity within the applied shear rate range (0.01–400 s−1). The highest viscosity (50 s−1) belonged to the dispersion of the gum treated for 20 min. CAP treatment significantly (p

In this study, a rapid, cost-effective, and environmentally-friendly approach was developed for the production of high-performance thin films to reduce the flammability of firwood as well as controlling its wettability. In this regard, a hydrophobic and flame-resistant organic thin coating was prepared through halogen-free plasma polymerization using a novel version of dielectric barrier discharge (DBD) apparatus optimized at atmospheric pressure. The home-made device does not require expensive vacuum instruments and operates in open-air using an organosilicon precursor (hexamethyldisiloxane (HMDSO)) as a liquid monomer. The morphology, composition, and chemical structure of the deposited polydimethylsiloxane-like (PDMS-like) thin films were comprehensively evaluated through FESEM, AFM, XPS, FTIR, EDX, and DTA-TG. The samples showed remarkable cross-linking. This innovative strategy made it possible to achieve the desired characteristics within a concise treatment time. The modifications include the increase in the static contact angle of super-hydrophilic firwood surfaces to 137.73°, enhancement of the surface roughness from 573 pm to 22.5 nm, and a significant reduction in the maximum rate of wood thermal decomposition from 0.94 to 0.65 mg min−1. Applying a creative and simple approach combining the image processing method with the heater test indicated that plasma modification of the wood surfaces improved their thermal stability without altering their aspect ratio or color surface. Therefore, the plasma-synthesized PHMDSO layers prepared by this device could be a promising candidate for fire retardancy and water repellency applications.

In this study, at atmospheric pressure, a dielectric barrier discharge (DBD) plasma was used to deposit the diamond-like carbon film doped by nitrogen atoms (N-DLC) on a glass substrate. The nitrogen gas was sent to the n-hexane container by bubbling technique and finally, n-hexane/ nitrogen vapor was guided to the plasma gap. The composition and the structure of the deposited films were studied by FTIR and Raman spectra and EDX analysis. The effect of deposition time on optical, electrical, and mechanical properties of coated films was investigated. Changes in N-DLC film characteristics were assigned to the decreased hydrogen participation rate during the growth process and increasing both sp2 cluster size and sp2 content. The surface morphology of films was analyzed by FESEM and AFM assay.

At atmospheric pressure, dielectric barrier discharge of a mixture of nitrogen gas and n-hexane solution has been used to deposit N-DLC films on Pyrex glasses. The composition and the structure of the deposited films have been studied by FTIR and Raman spectra. The surface morphology of films is performed by analyses of FESEM, EDX, and AFM. According to the results of Raman spectra, the ID/IG ratio has been decreased, FWHM of G peak has been increased and the G peak position has been moved to lower wavenumbers. Based on obtained results, increasing electrical discharge power leads to increasing sp3 content and structural transition from the graphitized to amorphous structures. The sp3 content is related to C–H, C–C, and C–N bonds. With the more formation of C–C and C–N bonds than C–H bonds, mechanical properties of hardness and scratchability are strengthen while more increment of C–H bonds in the deposited films compared to two other bonds leads to decrease these properties. Discharge power increment leads to the changing of the adhesion strength as another the mechanical property due to the variation of the hydrogen content, the surface bonding rate, and penetration of the species to the substrate.

Background In recent years, cold physical plasma gained significant interest as a new anticancer tool. Cold plasmas are versatile apparatuses in medicine and material processing. Among different cold plasma devices, the argon plasma jet is an effective apparatus and favorite for researches in plasma medicine science. Methods We developed an argon plasma jet for cancer treatments. Using optical emission spectroscopy, the newly developed plasma jet produced a substantial amount of hydroxyl radicals and other reactive oxygen and nitrogen species known to show cytotoxic effects at higher concentrations. In this work, we studied the efficacy of the argon-based plasma jet treatment in murine B16 melanoma cells in vitro and in vivo. In vitro, cell viability, apoptotic gene expression, and cell death patterns were assessed at 24 h and compared against non-malignant murine dermal fibroblasts (MDF). In vivo, B16 cells inoculated into the flank of the mice developed melanoma tumors, which were plasma-treated for 5 min on days 1, 5, and 10 or were left untreated. Results Melanoma cells were significantly more sensitive to plasma treatment than MDF under the same in vitro conditions (p= 0.00023). The results revealed that the argon-based plasma jet damaged B16 melanoma cells in vitro selectively without a detrimental effect on non-malignant MDF cells. In the animal model, the tumor volume was significantly reduced after three treatments with the plasma jet(p Conclusions The argon plasma jet showed therapeutic anti-melanoma efficacy in vitro and in vivo, which may spur new research lines in melanoma therapy.

Dielectric barrier discharge plasma actuators have attracted a lot of attention to use as new technologies for active flow control. In this paper, an experimental investigation of a single unsteady plasma actuator driven by two simultaneous sinusoidal high voltages is carried out. The aerodynamic performance of this plasma actuator is investigated for flow control of a wind turbine blade. Leading edge separation control at Reynolds number of 0.26 × 10 6 and in a wide range of angles of attack including linear, stall, and post-stall regions is considered as the test case. The momentum imparted by the plasma actuator to flow is investigated via measuring induced electric wind velocity, which represents that the induced velocities in the steady mode, with v max ≅ 5 m / s, are higher than that of the unsteady mode. The important aspect of exciting the unsteady dielectric barrier discharge plasma actuator in this new approach is improving its efficiency through increasing the authority of momentum addition to flow and reducing the minimum input power for discharge ignition relative to its typical grounded structure. This can be very important practically in flow control applications where the amount of consumed energy is a substantial factor in determining the actuator's efficiency. The obtained aerodynamic results reveal that the unsteady plasma actuator has the best operation in post-stall angles of attack, which is of great importance for operation characteristics of wind turbine blades. The power spectral density of pressure time series illustrates that the unsteady plasma actuator affects the flow through instabilities of the separation layer and vortex shedding structure.

The aim of the present study was to evaluate the effect of cold atmospheric-pressure plasma (CAP) on the structural aspects and some physicochemical properties of gum arabic (GA), with emphasis on its surface properties. GA was treated at dielectric barrier discharge (DBD) plasma with ambient air for different times (20, 40, and 60 min). The optical emission spectroscopy (OES) was utilized to scope present active species in the plasma. Upon treatment, the structural, thermal and morphological variations, as well as changes in water contact angle, surface and interfacial tension, molecular weight, solubility, moisture content and color of the treated gums, were studied. Compared with GA, overall significant changes in the spectra of all treated gums were recognized, particularly in the range of 1200–1750 cm−1. Elemental analysis of surface demonstrated that both oxygen and nitrogen content of treated gum increased time-dependently. Plasma had no pronounced effect on the amorphous nature of GA. Water contact angle data showed that plasma treatment was surprisingly capable of transforming GA hydrophilic nature into hydrophobic. The surface roughness of the treated gums powder time-dependently increased. The molecular weight, solubility, and moisture content of treated gum nonlinearly decreased with increasing treatment duration. The surface and interfacial tension significantly decreased after CAP treatment. The thermal properties and color of the treated gums changed after CAP treatment. In total, this study confirmed that the CAP treatment was an efficient approach to improve surface properties of gum arabic.

The surface modification of cotton samples was carried out using a liquid (ethanol) electrospray-assisted atmospheric pressure plasma jet. X-ray photoelectron spectroscopy (XPS) and Raman analysis confirmed the successful deposition of diamond like carbon (DLC) nano structures on the cotton surface. The super hydrophobic state of the samples was probed by contact angle measurements. The water repellency of the layers was tuned by controlling the voltage applied to the electrospray electrode. An investigation of the morphological and chemical structures of the samples by field emission scanning microscopy, atomic force microscopy (AFM) and XPS indicated that the physical shape, distribution and amorphization of the DLC structures were successfully adjusted and improved by applying a voltage to the electrospray electrode. Finally wash durability of the best sample was tested for 35 cycles. In this work, the use of a well-developed atmospheric pressure plasma jet for DLC nano structures deposition can enable a promising environmentally friendly and low-cost approach for modifying cotton fabrics for super water-repellent fabric applications.