Glow Discharge Plasma Research Articles

Effect of Cold Plasma Treatment on Surface Modification of Rice Grains

The influence of cold plasma of atmospheric-pressure glow discharge on the surface properties of rice grains has been studied. It has been established that as a result of the impact of nonthermal atmosphericpressure glow-discharge plasma on the seed surface, the surface becomes hydrophilic and is characterized by a decrease in the contact angle, an increase in surface energy, and enhancement of surface roughness, indicating the effective formation of polar groups on the surface of rice grains.

Initiation of Artificial Radioactivity of Impurity Elements in a Lead Cathode under Conditions of a Glow Discharge

The possibility of initiation of nuclear chemical processes in the Pb cathode during a glow discharge in a low-temperature deuterium-containing nonequilibrium plasma leading to a significant (at times) decrease in the isotope content of some impurity elements (specifically, Zn) and increasing others (specifically, W, Fe, Mn, and Al). Such processes can be understood by introducing the existence in nuclear matter of metastable non-nucleon excitations of internal shaking (isu-states) formed by initiating actions on the nuclei of electrons with high (on chemical scales) kinetic energy Ee ~ 3–5 eV.

Forevacuum plasma-cathode electron source for generation of a ribbon beam over a wide pressure range.

We describe the results of our investigations of the generation of a ribbon electron beam (10 × 220mm2) by a two-stage discharge system based on a hollow-cathode glow discharge plasma. The source design enables operation in the pressure range 2 × 10-2 to 10Pa. At a beam accelerating voltage of 8kV, the beam current is 450 mA at a pressure of 2 × 10-2Pa and 150 mA at a pressure of 10Pa. To achieve a uniform current density distribution of the beam over its cross-sectional area, a special design of emission electrode was employed. This enabled us to reduce non-uniformities of the beam current density distribution to a level of 10%.

Synthesis of Iron Oxyhydroxide Nanostructures in Glow-Discharge Plasma at Atmospheric Pressure

Synthesis of Iron Oxyhydroxide Nanostructures in Glow-Discharge Plasma at Atmospheric Pressure

Characterization of niobium carbide film deposited on commercially pure titanium by low-temperature plasma glow discharge

Characterization of niobium carbide film deposited on commercially pure titanium by low-temperature plasma glow discharge

Determination of arsenic and antimony by atmospheric pressure glow discharge portable emission spectrometer with solid acid hydride generation

In this work, the use of solid acid hydride generation (HG) for the simultaneous determination of As and Sb in environmental water samples by miniaturized atmospheric pressure glow discharge plasma optical emission spectrometer (APGD-OES) was evaluated. It was found that HG with the use of sulfamic acid tablets can achieve comparable sensitivity with conventional HCl-KBH4 for As and Sb determination by APGD-OES, which avoids the safety issue encountered in the use of hydrochloric acid and greatly facilitates field analysis. Under optimal conditions, the obtained detection limits (LODs) are as low as 1.26 μg L−1 for As and 0.72 μg L−1 for Sb, respectively. Moreover, it offers good repeatability, where the relative standard deviations (RSDs) are less than 2.5%. The accuracy of the proposed method was validated by the analysis of simulated natural water reference samples. Furthermore, it has been successfully applied to the determination of tap water, pond water, and hot spring samples. All these results clearly demonstrate the proposed simple, cost-effective and field-deployable method provides a promising approach for the field analysis of As and Sb.

Influence of atmospheric and vacuum plasma processing on the organic composition of araça-boi (Eugenia stipitata) juice

Cold plasma is a novel non-thermal technology that is still under development. Cold plasma treatment of food products induces a wide range of chemical changes in food compounds, several of which can improve nutritional quality. Understanding the chemical changes caused during plasma treatment is essential to enhance food quality and avoid the formation of undesired compounds. This investigation addressed the influence of two cold plasma technologies, glow discharge plasma and dielectric barrier discharge plasma, on the organic composition of araça-boi (Eugenia stipitata) juice, which is rich in sugars, organic and amino acids. The chemical composition of the juice was assessed by 1H nuclear magnetic resonance coupled with chemometrics. The effects of excitation frequency, processing time, and plasma flow rate were investigated. Glow discharge plasma and dielectric barrier discharge plasma application tended to decrease the concentration of glucose (33%), fructose (31%), malic acid (25%), and amino acids while increasing sucrose content (23%). Overall, plasma processing changed the juices’ alcohol, sugar, and amino acids content, primarily by reducing the concentration of cysteine (33%), alanine (42%), and methionine (43%). However, the dielectric barrier discharge plasma tended to slightly increase the amino acid content (up to 9%) when operating at 200 Hz.

3D-Printed PLA Scaffold with Fibronectin Enhances In Vitro Osteogenesis.

Tricalcium phosphate (TCP, Molecular formula: Ca3(PO4)2) is a hydrophilic bone graft biomaterial extensively used for guided bone regeneration (GBR). However, few studies have investigated 3D-printed polylactic acid (PLA) combined with the osteo-inductive molecule fibronectin (FN) for enhanced osteoblast performance in vitro, and specialized bone defect treatments. This study evaluated PLA properties and efficacy following glow discharge plasma (GDP) treatment and FN sputtering for fused deposition modeling (FDM) 3D printed PLA alloplastic bone grafts. 3D trabecular bone scaffolds (8 × 1 mm) were printed by the 3D printer (XYZ printing, Inc. 3D printer da Vinci Jr. 1.0 3-in-1). After printing PLA scaffolds, additional groups for FN grafting were continually prepared with GDP treatment. Material characterization and biocompatibility evaluations were investigated at 1, 3 and 5 days. SEM images showed the human bone mimicking patterns, and EDS illustrated the increased C and O after fibronectin grafting, XPS and FTIR results together confirmed the presence of FN within PLA material. Degradation increased after 150 days due to FN presence. 3D immunofluorescence at 24 h demonstrated better cell spreading, and MTT assay results showed the highest proliferation with PLA and FN (p < 0.001). Cells cultured on the materials exhibited similar alkaline phosphatase (ALP) production. Relative quantitative polymerase chain reaction (qPCR) at 1 and 5 days revealed a mixed osteoblast gene expression pattern. In vitro observations over a period of five days, it was clear that PLA/FN 3D-printed alloplastic bone graft was more favorable for osteogenesis than PLA alone, thereby demonstrating great potential for applications in customized bone regeneration.

Hydration effect of whey protein treated by glow discharge plasma

Glow discharge plasma (GP) was used to study the hydration mechanism of whey protein with different moisture content (10%, 20%, 30%). When the moisture content was 20%, the effect was most obvious. Strong hydration effect was confirmed by Fourier transform infrared spectroscopy (FTIR) results with sharper, narrower and blue-shifted from 3283.49 cm−1 to 3286.26 cm−1, indicating the enhanced hydrogen bond. More flexible protein structure with a significant decrease in α-helix content (from 18.50% to 14.62%), β-sheet content (from 29.67% to 19.38%) and crystallinity degree (from 6.18% to 0.81%) was introduced. Whey protein underwent oxidation reactions of CC to C–O–C(H) and further to COOH, C–OH to C–O–C and sulfhydryl to disulfide bonds. The scanning electron microscopy (SEM) results showed that the treated whey protein was highly aggregated (from 55.40 μm to 226.87 μm) and formed porous and rough polymers. Additionally, the treated whey protein exhibited higher anti-oxidation activity, with DPPH, ABTS and OH free radicals increased by 14.55%, 11.08% and 15.56%. The water/oil holding capacity and light transmittance of whey protein was improved by 18.18%, 22.05% and 35.69%, respectively.

The Effect of Gas Flow Rate, Exposure Times and Ageing on the Physicochemical Properties of Water Activated by Glow Discharge Plasma Jet

The goal of this work is to look into how the glow discharge plasma jet system changes the chemical and physical features of water. In this work, the physical and chemical properties of water were studied by using a plasma jet with Argon gas. 10 cm3 of distilled water was put in a glass dish with a diameter of 5 cm and a depth of 1 cm. The system was run with an AC voltage of 12 kV and a frequency of 20 kHz, and the exposure time ranged from 1 to 30 minutes. With amounts of 0.7, 1.0, 1.5, and 2.1 l/min, kits made by the American company Bartvation were used to measure the types of reactive oxygen and nitrogen species (RONS) that were formed. The data showed that the levels of NO2, NO3, and H2O2 were all too high. It gets bigger over time and as the flow rate goes up. The pH goes down with time until it hits 3, and the temperature goes up until it reaches 33°C. However, the pH goes up with storage time, and after 24 hours the water is back to its natural pH of 7. The amount of NO2, NO3, in the air goes up a little bit, and then starts to go down rapidly after 6 hours. After 24 hours, it is close to zero. From this, it's clear that the glow discharge plasma jet device can make RONS, which can be used for biological purposes.&#x0D; &#x0D;

Observation of nontrivial Zak phase induced topological states in glow discharge plasma

Plasma blackout, which contains ablative impurities, strongly attenuates the signal of the reentry spacecraft. Traditional methods focus on mitigating electron densities and impurities around the antenna, and metamaterial-based electromagnetic methods have yet to be proven experimentally. We simulate the plasma blackout problem using laboratory plasma supported by gas discharge technology. Alumina pillars are embedded in the plasma background to form plasma photonic crystals, while topological phase transitions are achieved by shrinking and expanding pillars within a unit cell. The topological edge states (TESs) that are insensitive to weak impurities in the transport path are verified theoretically and experimentally. We introduce the glide-reflection (GR) symmetry in the nontrivial lattices to obtain the gapless edge states, which are exclusively observed in the acoustic systems. Meanwhile, the Δω of the gapless TES increases with the electron densities, ensuring a wide communication bandwidth. Furthermore, the strong coupling of heterostructure with GR symmetry in plasma photonic crystals is elucidated. Our work not only provides a new approach to the blackout communication problem but can also serve as a nascent experimental platform to investigate topological electromagnetic phenomena.

SPECTROSCOPIC INVESTIGATION OF ARGON DC GLOW DISCHARGE IN PLASMA MEDIUM

In this study, UV-VIS-NIR (Ultraviolet Visible Near-Infrared) spectra emitted from Argon Glow discharge plasma in a low vacuum were recorded with a high-resolution Czerny-Turner type spectrometer. Argon plasma was produced at a pressure of 5mTorr and with a voltage of 584 V. Argon plasma was produced between two parallel stainless steel plates anode and cathode with a diameter of 15 cm, a thickness of 0.8 cm, and a distance of 13 cm between them. The radiative and collisional processes of the Argon plasma medium were modeled by the PrismSPECT atomic physics software (Software). The distributions of ion densities were calculated using the Saha-Boltzmann equation. The intensity of the excited energy levels of Ar(I) and Ar (II) ions were calculated in the electron temperature range of (0.4-3.5eV) and the mass density of (10-4-10-1gr/cm3). The UV-Visible-NIR spectra were simulated and compared with experimental spectra. The ratios of the intensities of the ArII/ArI (1s22s22p63s23p44f1/1s22s22p63s23p54p1) spectral lines were obtained for different plasma temperatures and densities. The temperature of the argon plasma was obtained from the spectral line intensity ratios.

Simulation of DC glow discharge plasma with free-moving dust particles in the radial direction

A self-consistent fluid model is developed to investigate the radial distributions of dusty plasma parameters in a DC glow discharge, in which the extended fluid approach of plasma particles and the transport equations of dust particles are coupled. The electrical interaction between charged dust particles is considered in the model. The time evolution of radial distributions of dust density, plasma density, the radial component of electric field and the forces acting on dust particles when dust density tends to be stable, are obtained and analyzed under different discharge currents and dust particle radii. It is shown that the dust density structure is determined mainly by the radial electrostatic force, thermophoretic force and ion drag force in the discharge tube, and both discharge current and dust particle radius have an obvious effect on the transport processes of dust particles. The dust particles gather in the central region of the discharge tube for low discharge current and small dust radius, then dust voids are formed and become wider when the discharge current and dust radius increase. The plasma parameters in the dust gathering region are obviously affected by the dust particles due to the charging processes of electrons and ions to the dust surface.

Interplay between electron and ion plasma waves

We report the observation of the interplay between the first kind of high-frequency electron-dominated plasma waves (EPWs) and the second kind of low-frequency ion-dominated plasma waves (IPWs) in a DC glow discharge plasma experiment. On application of positive DC voltage on a probe immersed in plasma when the drift velocity of the electrons (vd) ≈1.3× the thermal velocity of electrons (vte), it gives rise to an instability resulting in the formation of double layers (DL). Under DL conditions, the anode sheath extends deep into plasma. The DL represents a nonequilibrium plasma condition that is known for the instabilities and excitation of plasma waves. In this experiment, the effect of the monotonic increase of plasma density fluctuations (δn≈0.01%) on the evolution of DL has been studied. The interplay between EPWs and IPWs is observed in the course of this investigation. The overall plasma response on density fluctuations is recorded as floating potential fluctuations (FPFs) which vary with an increase of δn. The FPFs exhibit order-chaos-order transition with the evolution of DLs. Further analysis of the fluctuations using the wavelet method gives a spectrum in both the time and frequency domains simultaneously. Wavelet spectra reveal that the nonlinear evolution of FPFs is a consequence of the interplay between EPWs and IPWs due to the trapping and detrapping of electrons in the extended anode sheath region. These results explain that the ordered oscillation corresponds to dominant EPWs and the chaotic fluctuations are due to the coexistence of EPWs and IPWs. This new understanding may assist to study the complex plasma behaviour observed in laboratories as well as space plasmas.

Development of breathable and liquid/wet bacterial penetration barrier composite laminated fabrics for surgical gown applications

Disposable surgical gowns are used to protect health care workers from microorganisms and body fluids to meet the needs of surgical applications. In addition to protection, it has a significant impact on the surgical team members’ comfort and thus, the success of the operations. In this study, a dual layer surgical gown-an outer layer of film and an inner layer of nonwoven fabric-was developed. Produced composite laminated fabrics are SMS (spunbond/meltblown/spunbond) nonwoven fabric laminated microporous polyethylene film and SMS (spunbond/meltblown/spunbond) nonwoven fabric laminated thermoplastic polyurethane films. These fabrics were compared with nonporous polyethylene film-coated SS (spunbond/spunbond) nonwoven fabric available in the local market. The study aims to investigate the effect of some structural factors of composite nonwoven laminated fabrics, including lamination process, manufacturing process, and film type; microporous or monolithic, nonwoven fabric manufacturing process, and helium atmospheric-pressure glow discharge plasma treatment, on their functional performance properties, including air permeability, water vapour permeability, hydrostatic pressure resistance, and wet bacterial penetration resistance. The results showed that the produced composite fabrics offer outstanding breathability and, thus, the surgical team members' comfort. Produced composite fabrics had no wet bacterial penetration of Staphylococcus aureus and thus contributed to the prevention of the transfer of bacterial pathogens to prevent surgical site infection or post-operative infection. Produced composite fabrics offer superior liquid barriers according to the barrier protection classification of the Association for the Advancement of Medical Instrumentation (ANSI/AAMI PB 70:12) and thus contribute to the prevention of the transfer of body fluids during surgical operations.

Influence of air plasma modification power on surface properties of basalt fibers and basalt/poly(butylene succinate) adhesion

In this study, basalt fibers were treated with air glow discharge plasma at the powers of 50, 100, 200, and 300 W to investigate the influence of plasma power on fiber surface treatment and basalt/poly(butylene succinate) (PBS) adhesion. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) images showed rougher fiber surfaces when the plasma power was higher than 50 W. Water absorption measurement results demonstrated that the wettability of plasma-treated groups was significantly improved. X-ray photoelectron spectroscopy (XPS) showed that the atomic ratio of O/C increased to 0.91, 1.05, 1.86, and 1.86 for the 50 W, 100 W, 200 W, and 300 W groups, respectively. Tensile testing results of single fibers showed no strength reduction after modification. Microbond pull-out test revealed an increase in the interfacial adhesion of up to 39.2 % between basalt fiber and PBS for the 300 W group. This study demonstrates that our air plasma treatment technique was effective in the modification process for improving the basalt/PBS interfacial adhesion, where the selection of appropriate plasma treatment power was critical.

Preparation of highly dispersed silicon spheres supported cobalt-based catalysts and their catalytic performance for Fischer-Tropsch synthesis

A series of silicon spheres supported cobalt catalysts were prepared by incipient wetness impregnation followed by decomposition under treatment of glow discharge plasma with different intensities. The catalysts were characterized by X-ray powder diffraction, N2 physical adsorption-desorption, H2 temperature-programmed reduction, transmission electron microscope and Fourier-Transform Infrared spectroscopy. The Fischer-Tropsch synthesis performance were tested on a fixed bed reactor. The influence of plasma treatment on cobalt dispersion, reducibility and cobalt-support interaction were analyzed and discussed. The results showed that the plasma-treated catalysts had better catalytic performance than the calcined sample. The Co/SP-P650W catalyst showed the highest reaction activity due to the proper cobalt dispersion and higher cobalt reducibility.

Functionalization of zirconia ceramic with fibronectin proteins enhanced bioactivity and osteogenic response of osteoblast-like cells.

Introduction: To overcome the genuine bioinert properties of zirconia ceramic, functionalization of the surface with the bioactive protein fibronectin was conducted. Methods: Glow discharge plasma (GDP)-Argon was first used to clean the zirconia surface. Then allylamine was treated at three different powers of 50W, 75W, and 85W and immersed into 2 different fibronectin concentrations (5µg/ml and 10µg/ml). Results and Discussion: After surface treatment, irregularly folded protein-like substances were attached on the fibronectin coated disks, and a granular pattern was observed for allylamine grafted samples. Infrared spectroscopy detected C-O, N-O, N-H, C-H, and O-H functional groups for fibronectin treated samples. Surface roughness rose and hydrophilicity improved after the surface modification, with MTT assay showing the highest level of cell viability for the A50F10 group. Cell differentiation markers also showed that fibronectin grafted disks with A50F10 and A85F10 were the most active, which in turn encouraged late-stage mineralization activity on 21d. Up-regulation of osteogenic related mRNA expression from 1d to 10d can be observed in RT-qPCR data for ALP, OC, DLX5, SP7, OPG and RANK biomarkers. These physical and biological properties clearly indicate that an allylamine and fibronectin composite grafted surface significantly stimulated the bioactivity of osteoblast-like cells, and can be utilized for future dental implant applications.

Stiffening of polydimethylsiloxane surface as result of exposure to low‐pressure argon discharge plasma

AbstractPolydimethylsiloxane (PDMS) surface has been exposed to negative glow discharge plasma of a low‐pressure discharge in pure argon for a duration varying from 10 s to 2 min. Shallow atomic force microscopy indentation experiments were performed to investigate the effect of plasma treatment on PDMS surface stiffness and adhesion energy to the silicon nitride indenter surface. The results showed an important increase in Young's modulus and a slight increase of work of adhesion. X‐ray photoelectron spectroscopy investigation of plasma‐treated PDMS surface showed a decrease of atomic content of carbon accompanied by an increase of oxygen content and suggests that the stiffening of PDMS surface can be attributed to generation of new cross‐linking Si–O–Si and Si–CH2–CH2–Si bonds between PDMS molecules.

Polishing and Local Planarization High-Precision HDC Capsules by Four-Cup-Type Technology for Inertial Confinement Fusion

In inertial confinement fusion (ICF) experiments, high-density carbon (HDC) is being evaluated as an alternative to the current point-design ablator material (glow discharge plasma) due to its high density and optimal opacity, which leads to a higher energy efficiency and implosion stability. Chemical vapor deposition–coated HDC capsules have a near-perfect surface figure but a microscopically rough surface, so polishing is needed to achieve the required nanometer surface finish. Herein, HDC capsule polishing is investigated with modified four-cup-type polishing technology. The surface morphology, microstructures, and wall thicknesses of the polished capsules were examined by multiple techniques, such as an optical microscope, scanning electron microscope, X-ray radiography, and so on. The results show that the HDC capsules can be polished to a surface roughness less than 15 nm and a wall thickness nonuniformity of about 0.5 μm. The Raman spectra indicated that four-cup polishing had no obvious influence on the original surface crystallinity and phase composition of the HDC capsules. The crystallographic of the HDC capsules with different four-cup polishing times had no deterioration. This work plays an important role for the application of HDC capsules in ICF research.