Plasma Exposure Time Research Articles

Apoptotic Impact of Heliox Cold Plasma on a Cervical Cell Line Using Gold Nanoparticle-Doped Graphene Oxide Nanosheets

Background: Invasive cervical cancer is recognized as the second most common malignancy in women after breast cancer. Objectives: This study investigates, for the first time, the effect of gold nanoparticle-doped graphene oxide (GO) nanosheets on the human epithelial carcinoma (HeLa) cell line in the presence of heliox cold plasma. Methods: Graphene oxide nanosheets were synthesized using the Hummer method and then doped with gold nanoparticles. The nanoparticles were characterized by transmission electron microscopy (TEM), and the diffraction peaks of GO and gold nanoparticles were confirmed through X-ray diffraction (XRD) analysis. Additionally, the optical absorbance of the nanoparticles was measured in the range of 200 - 900 nm using UV-Visible spectroscopy. A plasma generator was fabricated to produce cold plasma using helium (He) and oxygen (O₂) gases at a 99:1 ratio. The radicals generated by the cold plasma were analyzed via optical emission spectroscopy (OES). Cell treatment was conducted by applying various concentrations of GO and GO/Au nanoparticles. Cellular phenotype was monitored through optical microscopy, and biocompatible concentrations of both nanoparticles were determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Subsequently, cold plasma at varying distances and durations was applied to the nanoparticle-treated cells. The generated radicals and the expression of apoptotic genes in treated cells were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and real-time PCR, respectively. Results: The width of the bacillus-like gold nanoparticles was 15.13 ± 0.96 nm. The cold plasma generated radicals such as N2I2⁺, N2II1⁻, He•, and O⁻•. XRD analysis confirmed the successful coupling of gold onto the GO nanosheets. The biocompatible concentrations of GO and GO/Au nanoparticles were found to be 30 µg/100 µL and 20 µg/100 µL, respectively, as determined by the MTT assay. Radical formation increased as incubation time was extended from 30 to 60 seconds. Furthermore, real-time PCR analysis demonstrated the highest levels of p53, Bax, and caspase 3/8 expression at a plasma exposure time of 60 seconds in the composite-treated group, while Bcl2 expression was significantly reduced. Conclusions: The findings suggest that the parameters of heliox cold plasma and the concentrations of GO/Au nanoparticles must be optimized to effectively induce apoptosis in cervical cancer cells.

Effective control of citrus green mold using plasma-activated water with hydrogen peroxide vapor: A non-thermal approach

In this study, a novel approach for controlling Citrus sinensis Salustiana green mold disease in oranges was developed using plasma-activated water (PAW) generated by a Surface Dielectric Barrier Discharge (SDBD) system reinforced with H2O2 cold vapor. Penicillium digitatum, the primary cause of orange mold, was the target of the treatment. The efficiency of the setup was investigated in three stages. First, a suspension of P. digitatum spores was directly treated with Ar/H2O2 plasma to estimate the optimal plasma exposure time required for maximum fungal inactivation. Second, the impact of Argon/H2O2 plasma-treated water (PTW), generated from various plasma exposure times, on mold growth on orange peels was examined. For this, orange peels were placed in Ar/H2O2-PTW for different durations, and mold occurrence was monitored. Finally, the effect of PTW, generated from various Ar/H2O2 plasma exposure times, on mold growth on whole oranges was investigated. Oranges were treated with Ar/H2O2-PTW for different durations, and mold occurrence was analyzed. The results demonstrated that a 20-min treatment of oranges with PTW produced from a 420-s Ar/H2O2 plasma exposure time led to complete inactivation of P. digitatum. This study showed that this hybrid scenario can be effectively used for fungal decontamination in the food industry.

An Integrated Microcurrent Delivery System Facilitates Human Parathyroid Hormone Delivery for Enhancing Osteoanabolic Effect.

Human parathyroid hormone (1-34) (PTH) exhibits osteoanabolic and osteocatabolic effects, with shorter plasma exposure times favoring bone formation. Subcutaneous injection (SCI) is the conventional delivery route for PTH but faces low delivery efficiency due to limited passive diffusion and the obstruction of the vascular endothelial barrier, leading to prolonged drug exposure times and reduced osteoanabolic effects. In this work, a microcurrent delivery system (MDS) based on multimicrochannel microneedle arrays (MMAs) is proposed, achieving high efficiency and safety for PTH transdermal delivery. The internal microchannels of the MMAs are fabricated using high-precision 3D printing technology, providing a concentrated and safe electric field that not only accelerates the movement of PTH but also reversibly increases vascular endothelial permeability by regulating the actin cytoskeleton and interendothelial junctions through Ca2+-dependent cAMP signaling, ultimately promoting PTH absorption and shortening exposure times. The MDS enhances the osteoanabolic effect of PTH in an osteoporosis model by inhibiting osteoclast differentiation on the bone surface compared to SCI. Moreover, histopathological analysis of the skin and organs demonstrated the good safety of PTH delivered by MDS in vivo. In addition to PTH, the MDS shows broad prospects for the high-efficiency transdermal delivery of macromolecular drugs.

Diffuse plasma surface modification of natural rubber-based composite

The article investigates the effect of diffusion plasma exposure time (30 s, 60 s) on the physicochemical properties of the surface of a natural rubber-based composite. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with dispersive X-ray spectroscopy (EDS) were used to assess the properties. Wettability and surface free energy tests were also performed. The application of plasma leads to surface oxidation (EDS). The obtained properties did not change for 21 days, and the plasma exposure time had no significant effect on the physicochemical changes of the composite surface.

Surface treatment optimization of mixed cellulose ester membrane by cold plasma treatment to improve apple juice clarification

This study aimed to determine the optimal conditions for the surface modification of mixed cellulose ester (MCE) microfiltration membrane by cold plasma (CP) for apple juice clarification. Response surface method using central cubic design (CCD) was employed for the optimization of the membrane surface modification process. Plasma gas type (oxygen, carbon dioxide, and air), power (10, 15, and 20 W), and exposure time (120, 180, and 240 s) were used as the factors for cold plasma surface modification. The results revealed the surface modification of the MCE membrane using air as plasma gas with plasma power and exposure time equal to 10 W and 180 s resulted in the maximum permeate flux in apple juice clarification. The results of scanning electron microscope, and atomic force microscope confirm the effect of CP treatment on the membrane surface roughness. Fourier transform infrared spectroscopy showed the incorporation of the hydroxyl group into the membrane surface due to CP treatment which affected the surface contact angle and hydrophilicity. The CP treatment of the membrane significantly affects the membrane resistances. Also, the surface modification of the MCE membrane using the CP treatment process in optimal conditions is an effective method for clarifying apple juice.

Potential of cold plasma pretreatment for preserving biochemical attributes and ensuring the microbiological safety of saffron stigma.

Saffron, similar to numerous other agricultural commodities, is susceptible to microbial contamination during cultivation and postharvest handling. Cold plasma treatment has emerged as an effective method for microbial inactivation while preserving food quality. The aim of this research was to preserve the color integrity and minimize the presence of microorganisms in dried saffron stigma by implementing cold plasma pre-treatment. Process parameters were optimized using the response surface method (RSM), considering the type of atmosphere (argon and air), plasma exposure time (1, 5, and 10 min), and plasma power (40, 70, and 100 W) as independent variables. The objectives were to maximize crocin content and minimize the total microbial load. The analysis of the response surface revealed that the argon atmosphere had a more significant impact on reducing microbial contamination than air, and an increase in plasma exposure time led to a decrease in microbial load. The maximum reduction in microbial load, by 0.9 logarithmic cycles compared to the control, was achieved with a 10-min treatment at 40 W power. Extended plasma exposure durations led to a minor reduction in the color, taste, aroma, and antioxidant properties of saffron stigma. Specifically, the color, taste, and aroma decreased by 0.5%, 0.5%, and 0.08%, respectively, with longer plasma exposure times. The antioxidant activity decreased by 0.64% with prolonged exposure time. However, the plasma-treated samples did not show any signs of Escherichia coli, mold, or yeast. Furthermore, our findings demonstrated that the type of atmosphere significantly influenced the reduction of infection and maintenance of saffron stigma's color quality. Cold plasma pretreatment holds promise as a viable method for preserving the physicochemical attributes of saffron while effectively reducing microbial contamination.

Optimisation of nitrogen plasma exposure time for surface modification of cotton fibre

Surface modification via plasma treatment is useful in improving textile-based wound dressing functionality. This study was conducted to optimise the nitrogen plasma exposure time and its effect on the cotton surface (CS) properties at a constant nitrogen flow rate of 20 sccm for 5 to 30 min. The optimisation was done by analysing the alteration in morphology, functional group composition, crystallinity phase, electrokinetic potential, and colour of CS as subjected to nitrogen plasma. CS experienced an etching effect due to the presence of microcracks on its surface, with its electrokinetic potential becoming less negative, ranging from -5.51 to –8.05 mV. Then, the nitrogen functional group was detected on CS ranging from 2.9% to 4.5%, with its whiteness index reduced to 8.67% compared to the pristine cotton. As a result, 20 min was selected as the optimum exposure time for surface treatment. An exposure time of 30 min showed an early sign of degradation, which reduced its crystallinity index by 11.1%. Apparently, the CS is activated as exposed to the nitrogen plasma and experiences slight changes in its molecular structure without affecting its bulk properties.

Corona discharge plasma for green de-inking of inkjet printer ink

This work features a new corona discharge plasma technology for de-inking yellow, blue, and red colors on various papers. This work was developed to minimize the chemical and environmental impacts of de-inking processes. A nonchemical contribution, operating at room temperature and atmospheric pressure, reduces the environmental impact of the process. The deinkability factor (DEMLab) values for all papers are determined with the optimal assessment results provided by a 36-mm variation gap at 2-min (blue) and 10-min (yellow and red) plasma exposure times, followed by applied voltages of 20 kV (yellow), 16 kV (blue), and 20 kV (red). The corona discharge plasma led to 48.58% (yellow printed paper), 64.11% (blue printed paper), and 41.11% (red printed paper) deinkability without altering the physical properties of the paper itself. The change in the tensile strength for the plasma-exposed paper was relatively little, less than 10%, compared to that of common recycling. The tensile strength of the untreated white paper was 5065 ± 487.44 N/mm2, and that of the plasma-treated printed paper was 4593 ± 248.47 N/mm2. It appears that there is little impact on the physicochemical properties of paper induced by the corona plasma treatment during the de-inking process.

Surface activation of viscose textiles via air, argon, and oxygen dielectric barrier discharge plasma: influence of peak voltage

This paper discusses the use of atmospheric pressure dielectric barrier discharge (DBD) plasma treatment to enhance the surface qualities of viscose fabrics. The study explores the effects of different plasma gases, discharge voltages, and exposure times on the treated fabrics. The findings emphasize the importance of optimizing the plasma’s peak voltage to achieve the desired surface treatment outcomes. The document also presents data on colour strength, wettability, colour fastness, and tensile strength of the treated fabrics, as well as scanning electron microscopy (SEM) analysis of surface morphology and chemical analysis using fourier- transition infrared spectroscopy (FTIR) and energy dispersive X-ray (EDX). The results show that treatment at a peak voltage of 11.83 kV is more efficient, except for the tensile strength which is enhanced at a peak voltage of 8.92 kV. The oxygen plasma treatment significantly improves the colour strength, which exhibits an increase from 11 to 18. The intensified colour was attributed to the significant influence of electrostatic interactions between the charged hydroxyl groups of the oxygen plasma treated viscose textiles and the dye molecules, which enhance the printability. The oxygen DBD plasma exhibits a higher ability to enhance the properties of textiles when compared to air and argon plasmas. This study presents a sustainable, economical, secure, and ecologically friendly approach to explore new fabrics for specific uses.

Plasma‐Enhanced Chemical‐Vapor‐Deposited SiOx(Ny)/n‐type Polysilicon‐on‐Oxide‐Passivating Contacts in Industrial Back‐Contact Si Solar Cells

In this article, different in situ grown plasma‐enhanced chemical vapor deposition (PECVD)‐grown interfacial oxides for n‐type polysilicon‐passivating contacts are investigated. Herein, SiOx(Ny)/n‐type amorphous silicon stacks created from either N2O plasma or O2 plasma are applied to POLy‐silicon on Oxide interdigitated back‐contact (POLO IBC) solar cells using the structured deposition process through a glass mask to create the IBC layout. The impact of plasma exposure time for interfacial oxide growth on solar cell efficiencies is experimentally determined. In the POLO IBC cell results, it is shown that the PECVD oxides SiOxNy and SiOx with optimized plasma exposure time give similar maximum efficiencies of 23.8% and 23.7%, respectively. In these data, the feasibility to deposit a high‐quality in situ PECVD interfacial SiOx(Ny) layers for surface passivation and current transport of passivated contacts at the same time is demonstrated. For the SiOx/n‐type polysilicon stack, it is found that both plasma exposure time for interfacial oxide growth and polysilicon anneal temperature variations can lead to similar optimum of solar cell efficiencies. The current open‐circuit voltage losses due to metallization for the solar cells are analyzed and a realistic efficiency of 25.22% is calculated to achieve optimized POLO IBC solar cells applying the synergistic efficiency gain analysis on Quokka3 simulations.

Numerical Analysis for Predicting the Rate of Graphitization on Wood Biomass During the Plasma-Assisted Pyrolysis

Abstract The plasma-assisted pyrolysis process is a powerful treatment for converting wood biomass to graphitic carbon. In order to make this process more precise and effective in time, the rate of graphitization data is needed, especially for predicting the effective time of treatment. In this study, numerical analysis is conducted to predict the rate of graphitization. An explicit finite difference method is applied for the numerical analysis. Some initial parameters used are the wood thickness (5 mm), coefficient of diffusivity (0.082 mm2/s), input plasma temperature (4,000 C), initial wood temperature (35 C), and room temperature (27 C). The analysis was conducted with a variation of time differences of 1 s, 2 s, 3 s, 4 s, and 5 s. The assumption used in this analysis is that the minimum temperature for graphitic carbon conversion is 2,000 C. The result of this study is the values of graphitization rates and exposure times summarized in TABLE 1. Therefore, this numerical analysis can successfully be used to predict the rate of graphitization and plasma exposure time for different wood biomass thicknesses.

Argon nonthermal plasma etching of poly(L-lactic acid) films: Tunning the local surface degradation and hydrolytic degradation rate

Plasma technology is widely used in the industry for the surface modification of polymeric materials, improving the adhesion of paints in polymeric packaging and cellular adhesion on polymers' surfaces without using hazardous chemicals. Plasma etching is a fast way to modify polymers, creating new nanostructure surfaces and adding chemical groups for new applications like antimicrobial surfaces. Poly(L-lactic acid) (PLLA) is a biodegradable polymer with exciting properties for biomedical, tissue engineering, food packaging, and other applications. In many cases, these products must undergo plasma surface treatments to meet the technical requirements of their function. Herein, we evaluated the effects of surface modification of PLLA using Argon nonthermal plasma etching. The results from Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray Excited Photoelectron Spectroscopy (XPS), and Matrix-assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-ToF-MS) show that increasing the plasma exposure time causes an enhancement in bulk and local surface degradation, crystallization kinetics and susceptibility to hydrolytic degradation for PLLA. Atomic Force Microscopy (AFM) show that the PLLA films present the highest surface roughness after 60 s of plasma etching times. Our findings suggest that plasma etching can be a suitable tool to adjust the polymer degradation rate to design intracorporeal devices with controlled degradation kinetics.

Tailoring the structural, morphological, surface wettability and hardness features of Makrofol HS for surface applications: effect of DBD treatment

ABSTRACT In current research, Makrofol HS polymeric films have been utilized to evaluate the alterations in the surface properties under an atmospheric-pressure dielectric barrier discharge (DBD) plasma source. Upon DBD plasma exposure with various exposure durations ranging from 10 min to 120 min, the structural, surface wettability, surface free energy, surface roughness, and hardness features of Makrofol HS films have been studied and analyzed using different techniques. The FTIR spectra demonstrated that small changes in the band intensities correspond to the C-O-C as well as C=O bonds. Further, the changes in the absorption bands are correlated to the treatment time, leading to two critical processes, degradation, and crosslinking. The results of surface wettability displayed that the liquids' contact angle decreased from 84 ± 3o, 77 ± 3o and 62 ± 2o for water, glycerol, and dimethyl to 45 ± 1o, 42 ± 1o, and 36 ± 1o for untreated and treated samples at the highest treatment time, respectively. Also, the surface free energy significantly amended with increasing plasma exposure time. This modification in the treated surface indicates the increase in the polar groups on the treated surfaces, which then become hydrophilic surfaces. The samples' surface roughness parameters Ra, Rq, and Rz increased from 0.057 ± 0.003, 0.084 ± 0.004 and 0.366 ± 0.02 mm for untreated samples to 1.463 ± 0.073, 1.707 ± 0.085, and 6.839 ± 0.34 mm for treated samples at the highest treatment time, respectively. The Vickers hardness measurements showed an increase in the Vickers hardness from 12.31 ± 0.61 kgf/mm2 for the untreated sample to 44.89 ± 2.24 kgf/mm2 for the treated sample at the highest duration.

The impact of large volume atmospheric pressure air glow discharge plasma on enhancing denim fabric (textile) sewing process

A direct-current large-volume atmospheric pressure air glow discharge plasma (APAGDP) was developed to enhance the sewing process of denim fabric. The generated plasma was characterized optically, electrically, and spectroscopically. The generated plasma presents a positive electric resistance behaviour. The plasma emission spectra are dominated by the nitrogen second positive system. Its intensity increases with the applied voltage. The generated plasma was used as a pre-treatment to enhance the sewing of the denim fabric at different exposure times, from 5 to 600 s. The scanning electron microscopy images showed no damage to the surface morphology of the denim fabric after plasma treatment. The sound pressure level (SPL) was used to verify the plasma effect on the denim fabric as compared to the untreated fabric. The SPL decreases with plasma exposure time. This result indicates that the plasma improves the sewing performance of the denim fabric.

Regeneration of oxygenated functional groups on thermally reduced graphene oxide nanosheets via diluted oxygen DBD cold plasma

Although stacked graphene oxide (GO) possesses abundant oxygenated functional groups, it suffers from limited specific surface area. This study aims to enhance the specific surface area of graphene oxide via thermal expansion and subsequently oxygenated functional groups using a dielectric barrier discharge (DBD) cold plasma. GO was synthesized via improved Hummer's method, followed by rGO reduction at 520 ℃. The rGO was treated by DBD cold plasma with N2 and O2 gases at various powers and exposure times. The resulting samples were characterized using several techniques, including TPD, FTIR, Boehm titration, BET, Raman spectroscopy, FESEM and EDS. The results showed that increasing O2 in the feed gas up to 47 % and plasma power enhanced oxygenated functional groups on plasma-functionalized rGO (PF-rGO). The exposure time significantly influenced the oxygen content of the functional groups; PF-rGO samples with 5 min exposure time exhibited superior specific surface area, water stability, and Cd2+ adsorption capacity compared to samples treated for 15 min. As plasma exposure time increased, layer stacking and oxygenated group density increased. Raman spectroscopy confirmed the enhancement of oxygen groups on the rGO surface treated with O2-N2 plasma. These findings provide valuable insights for designing and developing of graphene-based materials with tailored properties and enhanced performance for energy-related applications.

Unleashing the Power of Plasma and Flow: A Novel Cold Plasma‐Oscillatory System for Enhanced Continuous Biodiesel Production from Sunflower Oil

While fossil fuel resources are limited, the increasing demand for energy in the industrial and transportation sectors has led to using renewable fuels. This study aims to improve biodiesel production from sunflower oil by combining cold plasma and oscillatory systems through a transesterification process. The four main operational variables are examined, such as molar ratio (MR) (1:6–1:12), catalyst concentration (CC) (0.5–1.25 wt%), plasma exposure time (PET) (25–75 s), and residence time (RT) (30–90 s). The smooth periodic constriction reactor's physical attributes, including the diameter of the tube (D), the diameter of the constricted region (d0), and the distance between baffles (l), as well as the properties of the cold plasma system, are determined. The data analysis presents that PET, RT, CC, and MR have the greatest effect on efficiency. This optimization indicates that by exposing the reaction mixture to plasma for 59.99 s, adding 1.09% by weight of the catalyst, and with a MR of 7.17 in 86.43 s, biodiesel with a conversion percentage of 94.75% is produced. The results show that the optimum point matches with EN 14214 standard.

Long-term antifouling surfaces for urinary catheters.

The presence of a variety of bacteria is an inevitable/indispensable part of human life. In particular, for patients, the existence and spreading of bacteria lead to prolonged treatment period with many more complications. The widespread use of urinary catheters is one of the main causes for the prevalence of infections. The necessity of long-term use of indwelling catheters is unavoidable in terms of the development of bacteriuria and blockage. As is known, since a permanent solution to this problem has not yet been found, research and development activities continue actively. Herein, polyethylene glycol (PEG)-like thin films were synthesized by a custom designed plasma enhanced chemical vapor deposition (PE-CVD) method and the long-term effect of antifouling properties of PEG-like coated catheters was investigated against Escherichia coli and Proteus mirabilis. The contact angle measurements have revealed the increase of wettability with the increase of plasma exposure time. The antifouling activity of surface-coated catheters was analyzed against the Gram-negative/positive bacteria over a long-term period (up to 30 days). The results revealed that PE-CVD coated PEG-like thin films are highly capable of eliminating bacterial attachment on surfaces with relatively reduced protein attachment without having any toxic effect. Previous statements were supported with SEM, XPS, FTIR spectroscopy, and contact angle analysis.

Surface Passivation of Polymer Based Redistribution Layers for Area Selective Deposition of an Oxygen Barrier

Heterogeneous 3D integration is being hailed as the driver for new technologies due to its stacked device architecture. This increases functionality as the number and length of interconnecting wires decreases, in turn decreasing power consumption. In these advanced packaging technologies, the metal redistribution layers (RDLs) and the insulating polymer surrounding them are crucial components on which stringent reliability requirements are placed. The metal RDL’s are necessary to reroute signals from device level to packaging level. The polymer insulator, used as an alternative to traditional dielectric materials, must (i) be photosensitive to be compatible with lithography processing steps, (ii) possess high mechanical strength, (iii) exhibit good electrical performance, (iv) have a high thermal stability and glass transition temperature, and crucially (v) it must not be hygroscopic. Low or no moisture uptake of the polymer is essential as any moisture can cause mechanical and electrical reliability issues. Absorbed moisture can cause oxidation of Cu lines leading to the well-known problem of Cu diffusion resulting in voids, contact issues, delamination, electromigration and higher leakage currents.Area selective deposition (ASD) could greatly benefit these RDL’s by preferentially depositing an oxygen barrier to stop the oxidation of the Cu lines. The proprietary polymer used in this work is part of the WPR series by JSR Corporation and is a thermosetting phenol-based polymer which displays a high mechanical stability as it contains rubber nanoparticles, 70 nm in diameter. These are added to the polymer to increase the toughness and to prevent cracks and fractures forming and propagating through the film. However, achieving ASD with this polymer is difficult as the polymer is designed to have good adhesion properties so it will easily adhere to the Cu in the metal lines, and there are two materials of interest to passivate, the polymer itself and the rubber nanoparticles.In this work the surface is passivated by utilizing a polymerizing octafluorocyclobutane (C4F8) plasma which creates a Teflon-like film on the surface. The surface morphology and hydrophobicity are investigated to assess the best plasma exposure time, which was found to be 30 s. Surface chemistry from XPS analysis reveals surface modification through the deposition of fluorine rich groups from the 30 s C4F8 plasma exposure, Figure 1(a). Water contact angle measurements reveal an initial hydrophobic surface (~94°) but this hydrophobicity decreases over the course of several seconds. Following the 30 s C4F8 plasma exposure, the hydrophobicity increases significantly to above 110° and remains stable as shown in Figure 1(b). Surface morphology studies carried out by AFM demonstrates no increase in surface roughness following plasma exposure, Figure 1(c) and (d). ALD tests show the process to be selective to the tetrachloride family of ALD precursors. No selectivity was observed with tetrakis (dimethylamino) or isopropoxide based precursors. This process has the capability to block approximately 2 nm of TiO2 and HfO2 from these tetrachloride precursors. Studies of the same process on Cu substrates show that the metal surface is only temporarily modified, and ALD growth can still take place. Reliability stress and corrosion tests were performed to assess if the selectively deposited barriers could prevent Cu oxidation.Figure 1(a) C 1s XPS spectra showing difference before and after plasma treatment, (b) WCA value increases following plasma treatment, and AFM images in (c) and (d) show no change in the surface following plasma exposure. Figure 1

Synthesis of Mo2C-based material in DC arc discharge plasma under ambient air conditions

Molybdenum carbide is a well-known material, which properties makes it good candidate for replacing platinum in hydrogen production by electrolysis. Mo2C phase shows the best characteristics among other molybdenum carbide phases in HER. In this paper Mo2C-based powder material has been synthesized by non-vacuum DC arc discharge method. The main advantage of the method is the synthesis under ambient air conditions, which leads to low cost and more effectiveness of the process. We carried out several series of experiments to determine the optimal synthesis parameters that ensure the dominance of the Mo2C phase in the synthesis product. Carbon nanofibers (CNFs) obtained via catalytic pyrolysis of ethylene on Ni–Cu alloy were used as a carbon source. CNFs were characterized by SEM and low-temperature adsorption/desorption of N2. According to XRD analysis, the optimal ratio of the initial components C:Mo is 1:16 wt, arc current is 200 A, and plasma exposure time is 30 s. In this paper, for the first time the oxidation behavior of the Mo2C-based material, obtained in DC arc discharge plasma under ambient air conditions, was investigated by TG/DTA. The noble metal free HER electrocatalyst with the synthesized material as precursor was prepared for investigation of electrocatalytic activity.

Plasma Effects on Properties and Structure of Corn Starch: Characterization and Analysis.

This research investigated the impact of air plasma and high-pressure plasma treatments on corn starch. The resulting samples were characterized by particle morphology, molecular polymerization degree, molecular functional groups, and crystallinity. SEM analysis revealed that plasma treatment altered the surface morphology of corn starch, with variations observed depending on the duration of treatment. UV/Vis spectroscopy results indicated that longer plasma exposure times increased maximum absorbance values with less complete peak shapes. FTIR results demonstrated that plasma treatment disrupted the crystalline structure of starch, resulting in decreased molecular polymerization. Lastly, XRD results showed a proportional relationship between plasma treatment duration and the intensity of the diffuse peak, indicating that prolonged plasma exposure increased the amorphous nature of starch.