Mixture Plasma Research Articles

Dynamic modeling of air–metal plasma mixture of single-turn coil with erosion at megaGauss magnetic field

Single-turn coil (STC) is a destructive pulsed magnet aiming at 100–300 T magnetic field. Due to the high discharge current, the conductor of STC is heated rapidly and undergoes melting and vaporization, leading to the generation of supersonic air–metal vapor mixed plasma jet and the magneto-fluid effect. In this study, the mixed plasma mass-transfer and fluid dynamic characteristics are modeled at megaGauss magnetic field, high temperature, high pressure, and supersonic conductor shock deformation. The collision integral method is employed to calculate the fluid transport properties. In addition, a boundary constraint model of fluid–structure interaction (FSI) compatible with both fluid wall boundary condition and plasma jet entrance condition and a model to simultaneously solve the thermal ionization and high electric field ionization of the mixed vapor are proposed. As the result, the distributions of plasma electrical conductivity, current density, electron, heavy particles, temperature, air body load, and velocity are derived. Especially, the region of highest electrical conductivity is not the air domain near the inner surface of the conductor with the highest electron density and the highest magnetic field, but the air domain near the outer surface of the conductor with the relatively higher electron density and lower magnetic field.

Lyso-phosphatidylcholine as an interfacial stabilizer for parenteral monoclonal antibody formulations

Therapeutic proteins suffer from physical and chemical instability in aqueous solution. Polysorbates and poloxamers are often added for protection against interfacial stress to prevent protein aggregation and particle formation. Previous studies have revealed that the hydrolysis and oxidation of polysorbates in parenteral formulations can lead to the formation of free fatty acid particles, insufficient long-term stabilization, and protein oxidation. Poloxamers, on the other hand, are considered to be less effective against protein aggregation. Here we investigated two lyso-phosphatidylcholines (LPCs) as potential alternative surfactants for protein formulations, focusing on their physicochemical behavior and their ability to protect against the formation of monoclonal antibody particles during mechanical stress.The hemolytic activity of LPC was tested in varying ratios of plasma and buffer mixtures. LPC effectively stabilized mAb formulations when shaken at concentrations several orders of magnitude below the onset of hemolysis, indicating that the potential for erythrocyte damage by LPC is non-critical. LPC formulations subjected to mechanical stress through peristaltic pumping exhibited comparable protein particle formation to those containing polysorbate 80 or poloxamer 188. Profile analysis tensiometry and dilatational rheology indicated that the stabilizing effect likely arises from the formation of a viscoelastic film at approximately the CMC. Data gathered from concentration-gradient multi-angle light scattering and isothermal titration calorimetry support this finding. Surfactant desorption was evaluated through sub-phase exchange experiments. While LPCs readily desorbed from the interface, resorption occurred rapidly enough in the bulk solution to prevent protein adsorption. Overall, LPCs behave similarly to polysorbate with respect to interfacial stabilization and show promise as a potential substitute for polysorbate in parenteral protein formulations.

Summary of the 10th Asia-Pacific Transport Working Group (APTWG) Meeting

Abstract This conference report summarizes contributed papers and discussions presented at the 10th Asia-Pacific-Transport Working Group (APTWG) held at the Hanyang University, Seoul, South Korea from 13 to 16 June 2023. This year technical working groups were organized under following five topics: (A) isotope effect on transport and physics on isotope mixture plasma, (B) turbulence spreading and coupling in core-edge-SOL (scrape-off layer), (C) interplay between MHD topology/instability and turbulent transport (covering the negative triangularity issue), (D) interaction between energetic particle driven instability and transport (focusing on cross-scale coupling physics), and (E) model reduction and experiments for validation. Summaries of significant progresses from the presentations in the five technical working groups are given.

EFFECT OF SILVER DOPING ON IRON OXIDE ELECTRICAL PROPERTIES

Iron silver oxide (Agx[Formula: see text]O3; [Formula: see text]) structure for photoelectrochemical (PEC) water splitting was grown by RF–DC co-sputtering of an iron–silver target in argon/oxygen plasma mixtures at 300°C, followed by thermal annealing at 560°C. The chemical composition and structure of the deposited film can be tuned by controlling the metal doping and the annealing temperature. The thermal treatment extensively improves the PEC water-splitting performances of the films. XRD patterns of AgxFe[Formula: see text]O3 shown in the figure can be indexed to the hexagonal structure of silver oxide and the rhombohedral structure of hematite and new X-ray Diffraction (XRD) peaks of AgxFe[Formula: see text]O3 structure. The annealing and doping process seems to cause a serious change in the crystal structure of the thin film, it showed a serious change in its electrical properties. The electrical parameters of resistance for thin films were measured using the Hall measurement method at room temperature. With Hall measurements, the n-type carrier concentration of the Fe2O3 structure was calculated, and it was observed that its resistance was 1[Formula: see text]M[Formula: see text]. Likewise, it was observed that AgxFe[Formula: see text]O3 exhibited an n-type carrier concentration, and its resistance was calculated to be 0.5[Formula: see text]M[Formula: see text]. The conductivity change is based on silver doping. The doping process seems to cause a change in the bandgap of the thin film, it showed a change in its optical properties. The film’s optical absorption was measured by UV–Vis photo spectroscopy. Subsequently, the structural and topographic properties of AgxFe[Formula: see text]O3 structures were investigated by high-precision characterization devices.

An ultrasensitive green synchronous factorized spectrofluorimetric approach for the simultaneous determination of Favipiravir and Molnupiravir: Application to pharmaceutical, environmental, and biological matrices.

During the pandemic, Favipiravir (FVP) and Molnupiravir (MPV) have been widely used for COVID-19 treatment, leading to their presence in the environment. A green synchronous spectrofluorimetric method was developed to simultaneously detect them in environmental water, human plasma, and binary mixtures. Maximum fluorescence intensity was achieved at pH 8, with MPV exhibiting two peaks at 300 and 430 nm, and FVP showing one peak at 430 nm. A fluorescence subtraction method effectively removed interference, enabling direct determination of MPV at 300 nm and FVP at 430 nm. The method showed linearity within 2-13 ng/mL for FVP and 50-600 ng/mL for MPV, with recoveries of 100.35% and 100.12%, respectively. Limits of detection and quantification were 0.19 and 0.57 ng/mL for FVP and 10.52 and 31.88 ng/mL for MPV. Validation according to ICH and FDA guidelines yielded acceptable results. The method demonstrated good recoveries of FVP and MPV in pharmaceuticals, tap water and Nile water (99.62% ± 0.96% and 99.69% ± 0.64%) as per ICH guidelines and spiked human plasma (94.87% ± 2.111% and 94.79% ± 1.605%) following FDA guidelines, respectively. Its environmental friendliness was assessed using Green Analytical Procedure Index (GAPI) and the Analytical Greenness Metric (AGREE) tools.

Aqueous solution-processed In2O3 TFTs using focused plasma in gas mixtures

Solution-processed indium oxide (In2O3) thin films have been studied widely as active layers for transparent semiconducting devices because of their high charge carrier concentration, low absorbance, simple fabrication methods, and low cost. Several studies on improving the electrical characteristics of thin-film transistors (TFTs) by optimizing and fine-tuning the fabrication process and using various post-deposition treatments have been conducted to take full advantage of these semiconductor films in high-performance electronics. This study examined the effects of a focused plasma (FP) treatment on In2O3 thin films prepared using a simple solution process at 250 °C. The effects of the FP generated from N2 gas and two gas mixtures (N2-H2 and N2-H2-O2) on the electrical performance of the TFTs were analyzed. The FP treatment enhanced the electrical properties of the device, and the specific performance and stability parameters were improved by the treatment conditions. X-ray photoelectron spectroscopy showed that the FP treatment could effectively control the oxygen vacancies and carrier concentration in the solution-processed In2O3 thin films. Therefore, an FP beam is a viable method for optimizing In2O3 TFTs prepared at low temperatures for application in high-performance transparent electronic devices.

Association between exposure to plasma mixture of essential and toxic elements and the lipid profile in institutionalized older adults

BackgroundOlder adults have a progressive deficiency in the ability to detoxify chemical elements and are susceptible to dyslipidemia and changes in glycemic control. The objective was to evaluate the association of the mixture of essential and toxic elements in the plasma of institutionalized older adults and test the associations with lipid profile variables and glycemic control. MethodsData were obtained from 149 Brazilian older adults aged ≥60 living in nursing homes (NH) in Natal, Brazil. The concentrations of sixteen chemical elements in plasma and lipid profile parameters and glycemic control of 149 institutionalized older adults were measured. Bayesian kernel machine regression was used to estimate the associations of the mixture of chemical elements with total cholesterol (TC), high-density lipoprotein (HDL-c), low-density lipoprotein (LDL-c), triglycerides (TG), fasting glucose, and glycated hemoglobin. ResultsNon-linear responses to exposure were observed for iron (Fe) about TC, LDL-c, and TG, and for barium (Ba) and copper (Cu) about TG. The concentration of the mixture of chemical elements below the 35th percentile was associated with a decrease in TC. Fe was the main element in the effect of the mixture associated with TC. ConclusionsThe lower concentrations of the mixture of chemical elements in plasma had a protective effect on the increase in TC, with Fe being the main element. Considering the results, the levels of essential and toxic elements in the plasma of older adults require extensive screening, mainly to prevent dyslipidemia and monitor clinical interventions.

Formation of Black Silicon in a Process of Plasma Etching with Passivation in a SF6/O2 Gas Mixture.

This article discusses a method for forming black silicon using plasma etching at a sample temperature range from -20 °C to +20 °C in a mixture of oxygen and sulfur hexafluoride. The surface morphology of the resulting structures, the autocorrelation function of surface features, and reflectivity were studied depending on the process parameters-the composition of the plasma mixture, temperature and other discharge parameters (radical concentrations). The relationship between these parameters and the concentrations of oxygen and fluorine radicals in plasma is shown. A novel approach has been studied to reduce the reflectance using conformal bilayer dielectric coatings deposited by atomic layer deposition. The reflectivity of the resulting black silicon was studied in a wide spectral range from 400 to 900 nm. As a result of the research, technologies for creating black silicon on silicon wafers with a diameter of 200 mm have been proposed, and the structure formation process takes no more than 5 min. The resulting structures are an example of the self-formation of nanostructures due to anisotropic etching in a gas discharge plasma. This material has high mechanical, chemical and thermal stability and can be used as an antireflective coating, in structures requiring a developed surface-photovoltaics, supercapacitors, catalysts, and antibacterial surfaces.

Kinetic theory of weakly ionized plasma and electrolyte mixtures including Onsager matrix and frequency dispersion effects

AbstractWe summarize the method of hydrodynamic approximation for weakly ionized plasmas developed with Klimontovich in 1962 and give a generalization to many—component systems using Onsagers matrix theory and including dispersion effects. We develop the conductivity theory of complex plasma and electrolyte mixtures based on the model of charged hard spheres with given non‐additive contact distances, including frequency‐dependent electric fields. These generalizations are made with the aim to allow applications to complex natural systems as atmospheric plasmas and seawater. Finally, we give as an example a numerical calculation of the single ion conductivities of a six‐component seawater model.

Simultaneous determination of amlodipine besylate and azilsartan mixture in human plasma utilizing high-performance thin-layer chromatography with ultraviolet detection

Simultaneous determination of amlodipine besylate and azilsartan mixture in human plasma utilizing high-performance thin-layer chromatography with ultraviolet detection

Evaluation of the spatial structure of multiline emission in a capacitively coupled plasma using tomographic reconstruction

By imaging a capacitively coupled plasma from multiple directions using telecentric lens cameras and optical bandpass filters, the spatial structure of emission at specific wavelengths was reconstructed using the Tikhonov–Phillips regularization method. Camera parameters, crucial for relating three-dimensional structures to two-dimensional images, were evaluated experimentally to avoid a complex analytical approach. Assuming an axisymmetric emission profile, 750.4 nm Ar and 585.2 nm Ne emissions from Ar/Ne mixture plasma were reconstructed. The pressure dependence of the reconstructed Ar profile showed a similar trend to that of the two-dimensional emission images. The spatial structure of the emission intensity ratio of Ne to Ar from the reconstructed Ar and Ne profiles agreed well with a spatial distribution of electron temperatures measured with a Langmuir probe.

Kinetic Coefficients of Electrons in Weakly Ionized Plasma of Mixtures of Air with Water Vapor in a Strong Electric Field

Kinetic Coefficients of Electrons in Weakly Ionized Plasma of Mixtures of Air with Water Vapor in a Strong Electric Field

Damage caused by He and D plasma exposure in Mo/Zr-added W-Y2O3 composites

In the present study, we developed Mo- and Zr-added W-Y2O3 composites, and investigated their surface damage, including commercially available W induced by He and D as well as He and D mixture plasmas. Blistering was not observed in the D-plasma-irradiated W and W composites. The thickness of the damaged surface layer due to He plasma exposure of the W-Mo-Y2O3 composite was similar to that of W. However, the thickness of the damaged surface layer of the W-Y2O3 composite was half that of W. In addition, the thickness of the damaged surface layer of the W-Zr-Y2O3 composite was further improved by 5 times. Y2O3 nanoparticles, especially refined Zr-Y-O nanoparticles, act as He trap sites to suppress the formation and growth of He bubbles. Furthermore, the W-O-Y and W-O-Zr-Y nanoparticles increased the solubility of He and delayed He diffusion, hindering the formation of He bubbles.

Optical and transport properties of plasma mixtures from ab initio molecular dynamics

Predicting the charged particle transport properties of warm dense matter/hot dense plasma mixtures is a challenge for analytical models. High accuracy ab initio methods are more computationally expensive, but can provide critical insight by explicitly simulating mixtures. In this work, we investigate the transport properties and optical response of warm dense carbon–hydrogen mixtures at varying concentrations under either conserved electronic pressure or mass density at a constant temperature. We compare options for mixing the calculated pure species properties to estimate the results of the mixtures. We find that a combination of the Drude model with the Matthiessen's rule works well for DC electron transport and low-frequency optical response. This breaks down at higher frequencies, where a volumetric mix of pure-species AC conductivities works better.

Comparison of the Efficacy of Two Different Local Anesthesia Techniques for Mesotherapy in Temporal Region Alopecia.

Introduction Mesotherapy is a wide range of minimally invasive injections. In mesotherapy, a mixture of various tonics is injected into the skin. These include plant extracts, various medications, vitamins, enzymes, hormones, growth factors, and other factors that will help treat alopecia. Most commonly, a mixture of platelet-rich plasma (PRP) and vitamins is used. In mesotherapy treatment for hair regrowth in the temporal region, zygomaticotemporal nerve blocks, supratrochlear nerve blocks, and supraorbital nerve blocks are given. The zygomaticotemporal nerve, supraorbital nerve, and supratrochlear nerve are the branches of the trigeminal nerve. They provide sensation on the lateral side of the forehead, which is the temple region. Methods A sample size of 100 people was taken for the study who were undergoing mesotherapy in the bilateral temporal region for alopecia. Each group had 50 subjects: group I was given supratrochlear, supraorbital, and zygomaticotemporal nerve blocks as local anesthesia techniques, and group II was given supratrochlear and supraorbital nerve blocks. PRP was injected using an insulin syringe. Pain was assessed using a visual analog scale (VAS). Results During the procedure, a mean VASof 1 and 3 wasobserved in groups I and II, respectively, during the procedure (p-value0.023). A mean VASof 3 and 5 was observed in groups I and II, respectively, after three hours (p-value 0.000). This shows a significant difference in the pain experienced by the subjects between the groups. Conclusion This study proves that the zygomaticotemporal nerve, used along with supratrochlear and supraorbital nerve blocks, is better at producing analgesia and reducing pain.

Three-dimensional Modeling of the Solar Wind and Local Interstellar Medium Interaction with Pickup Ions in the Presence of Heliospheric Current Sheet

Our three-dimensional, time-dependent, multi-fluid model has been used to investigate the solar wind (SW)–local interstellar medium (LISM) interaction with pickup ions (PUIs) treated as a separate fluid. A non-zero, but fixed, angle between the Sun’s magnetic and rotation axis is adopted. The flow of the plasma mixture (thermal SW protons, PUIs, and electrons), is described by the system of ideal magnetohydrodynamic equations with the source terms responsible for charge exchange between ions and neutral atoms. Different populations of neutral atoms are governed by the individual sets of the Euler equations. As the standard Rankine–Hugoniot relations are not appropriate to describe the anisotropic behavior of PUIs at the termination shock, we use a kinetically-derived set of boundary conditions at it. We extend our previous work [1] and perform these new simulations on a Cartesian grid. This approach allows us to maintain a uniform grid resolution in all directions, without compromising resolution, at large distances from the Sun. The possibility of transition of the SW flow to a stochastic regime in the region between the termination shock and heliopause is further investigated.

Acetylene/argon mixture plasma to build ultrathin carbon bridge of CFx/C/MnO2 for high-rate lithium primary battery

Acetylene/argon mixture plasma to build ultrathin carbon bridge of CFx/C/MnO2 for high-rate lithium primary battery

Gas-kinetic scheme for partially ionized plasma in hydrodynamic regime

Most plasmas are only partially ionized. To better understand the dynamics of these plasmas, the behaviors of a mixture of neutral species and plasma in ideal magnetohydrodynamic states are investigated. The current approach is about the construction of coupled kinetic models for the neutral gas, electron, and proton, and the development of the corresponding gas-kinetic scheme (GKS) for the solution in the continuum flow regime. The scheme is validated in the 1D Riemann problem for an enlarged system with the interaction from the Euler waves of the neutral gas and magnetohydrodynamic ones of the plasma. Additionally, the Orszag–Tang vortex problem across different ionized states is tested to examine the influence of neutrals on the MHD wave evolution. These tests demonstrate that the proposed scheme can capture the fundamental features of ideal partially ionized plasma, and a transition in the wave structure from the ideal MHD solution of the fully ionized plasma to the Euler solution of the neutral gas is obtained.

Revealing the mechanism of interfacial adhesion enhancement between the SiO2 film and the GaAs substrate via plasma pre-treatments

The formation mechanism of a highly adherent silicon dioxide (SiO2) film on gallium arsenide (GaAs) substrate by plasma enhanced chemical vapor deposition (PECVD) is proposed. Ar, N2, and NH3 were used as pre-treatment gas to improve the interfacial adhesion. The interfacial adhesion was measured by the cross-cut tape test. By the measurement of spectroscopic ellipsometry and x-ray photoelectron spectroscopy (XPS), it is revealed that nitrogen plasma pre-treatment had formed a very thin GaN transition layer on the surface, which was responsible for the improvement of interfacial adhesion. XPS depth-profiling further confirmed various pre-treatment gases generate plasma mixtures and form thin film layers with different compositions on the GaAs surface. These layers have a significant impact on the adhesion of the subsequently prepared SiO2 film. The primary mechanism for improving interfacial adhesion is the renovation of the substrate composition via plasma pre-treatment by PECVD, which forms a transition layer of nitrides that eliminates the negative effects of oxides on adhesion. This study reveals the mechanism of interfacial adhesion enhancement between SiO2 film and GaAs substrate, which is of significant importance in fabricating high-performance and reliable semiconductor devices.

Frequency-dependent electron power absorption mode transitions in capacitively coupled argon-oxygen plasmas

Phase Resolved Optical Emission Spectroscopy (PROES) measurements combined with 1d3v Particle-in-Cell/Monte Carlo Collisions simulations are performed to investigate the excitation dynamics in low-pressure capacitively coupled plasmas (CCPs) in argon-oxygen mixtures. The system used for this study is a geometrically symmetric CCP reactor operated in a 70% Ar-30% O2 mixture at 120 Pa, applying a peak-to-peak voltage of 350 V, with a wide range of driving RF frequencies (2 MHz ⩽f⩽ 15 MHz). The measured and calculated spatio-temporal distributions of the electron impact excitation rates from the Ar ground state to the Ar 2p1 level show good qualitative agreement. The distributions show significant frequency dependence, which is generally considered to be predictive of transitions in the dominant discharge operating mode. Three frequency ranges can be distinguished, showing distinctly different excitation characteristics: (i) in the low frequency range ( f⩽ 3 MHz), excitation is strong at the sheaths and weak in the bulk region; (ii) at intermediate frequencies (3.5 MHz ⩽f⩽ 5 MHz), the excitation rate in the bulk region is enhanced and shows striation formation; (iii) above 6 MHz, excitation in the bulk gradually decreases with increasing frequency. Boltzmann term analysis was performed to quantify the frequency-dependent contributions of the Ohmic and ambipolar terms to the electron power absorption.