Plasma Characteristics Research Articles

Optical properties of nanoparticles in blood: considering blood absorption

Nanomedicine is emerging as a crucial avenue for exploring new therapeutic and diagnostic techniques in the medical field. Effective monitoring of the dispersion concentration of nanoparticles using optical methods is an extremely important topic in this area. However, existing research has not recognized that the light absorption of blood can lead to significant errors in related optical measurements. This paper, considering the absorption properties of the background medium, meticulously discusses the variations in the single-scattering characteristics of nanoparticles in plasma and whole blood, and analyzes the influence of parameters such as incident wavelength, particle size, refractive index, and background medium refractive index. The results indicate that neglecting the light absorption of the background medium may lead to differences of up to approximately 50% in the results, but this is also influenced by parameters such as incident wavelength, particle size, and refractive index. Furthermore, there are still significant differences in the variations of the single-scattering properties of nanoparticles with identical characteristics in plasma and whole blood. These results indicate the importance of in-depth research into calibration techniques for optical instruments in monitoring nanoparticles in the blood, and further enhance the development of nanoparticle monitoring technology in nanomedicine.

Study on hollow cathode discharge mode with high flow rate

Abstract Hall and ion propulsion systems at power levels of ten kilowatts or higher are in development or application stages in recent years, yet research on the operational characteristics of corresponding hollow cathodes remains incomplete. This study conducts experimental research using a hollow cathode with a rated condition of 15 sccm of krypton gas and 10 A of current. By supplying a larger flow rate, the study expands the range of discharge currents to investigate changes in the discharge modes. The plume plasma characteristics and spatial distributions under various conditions were measured using a Langmuir single probe mounted on a planar two-dimensional displacement platform. The experimental results indicate that at krypton flow rates of 25 sccm and 30 sccm, as the current increases, the anode voltage and discharge oscillations increase at first but decrease later. The discharge mode transitions from low-current spot mode to plume mode, and then back to spot mode at high current. The increase in anode voltage and oscillations during the first transition phase is gradual and continuous, while the decrease during the second transition phase is abrupt. Conditions of 10 A, 12.5 A, and 20 A were selected to represent these three modes for single-probe plume spatial diagnostics. The results indicate that in the high-current spot mode, the axial potential gradient is significantly reduced compared to the radial gradient, and the cathode plasma plume is more collimated. This study shows that at high flow rates, hollow cathodes may exhibit nonlinear impedance and undergo multiple discharge mode transitions, with each transition phase displaying distinct characteristics.

Enhancing microstructure, nanomechanical and anti-wear characteristics of spark plasma sintered Ti6Al4V alloy via nickel-silicon carbide addition

This study examines the nanomechanical and anti-wear behaviour of spark plasma sintered Ti6Al4V matrix composites reinforced with Ni and SiC particles. Microstructural analysis revealed the in-situ formation of the hard TiC, Ti3SiC2 and Ti5Si3 phases within the metal matrix. Nanoindentation analysis revealed that the composite containing 10 wt% SiC (TNi10SiC) exhibited significantly higher nanohardness (about 10.3 GPa) and elastic modulus (∼ 177.7 GPa) than the unreinforced Ti6Al4V alloy (sample T). The improved nanomechanical performance of the composites was attributed to the load-carrying capacity of the hard, in-situ formed reinforcement phases. The anti-wear characteristics of the composites showed that TNi5SiC composite displayed superior wear resistance with a specific wear rate of 4.75 ± 0.34 x 10-4 mm3/Nm and 2.15 ± 0.34 x 10-4 mm3/Nm under an applied loads of 10 N and 20 N, respectively, among the sintered samples. This represents about 67% and 29% reduction in specific wear rate relative to sample T. This enhanced tribological behaviour was ascribed to the increased surface hardness, the formation of a stable transfer layer, and the reduction in direct asperity contact at the sliding interfaces. However, reinforcement pull-out aggravates abrasive wear and leads to a higher specific wear rate for TNi10SiC composite. This work provides valuable information for advancing Ti6Al4V-based composites for enhanced structural and wear-resistant applications.

Numerical simulation of CuCr alloys vacuum arc under conditions of arc contraction, deflection, and anode vapor

In practical arc ignition processes of high-current vacuum arcs, despite the calibration effect of the axial magnetic field, the strong magnetic constriction force still causes the arc to contract. Additionally, during the actual electrode opening process, due to the random nature of the arcing position, the center of the arc column is often not located at the center of the electrode. At this point, the behavior of the vacuum arc can be understood as an asymmetric three-dimensional (3D) process under the influence of the spatial magnetic field, affecting the generation of anode vapor and the characteristics of arc species. Therefore, it is useful to conduct simulation studies on multi-species vacuum arc behavior considering arc contraction and arc deflection. In this paper, the spatial magnetic field distribution under different electrode effective areas and different arc center deflection distances have been simulated, and the influence of actual magnetic field-induced by arc contraction and deflection on 3D spatial distribution characteristics of arc plasma has been studied based on a 3D multi-species (CuCr alloys) vacuum arc model with anode vapor. The simulation results show that with the contraction of the arc column, the area occupied by neutral atomic vapor decreases correspondingly, but the ionization and recombination process between the arc column regions becomes more intense. The axial current density and electron temperature distribution around the neutral atomic vapor area become more non-uniform. When the arc column deviates from electrode center, the neutral atomic vapor area shows an asymmetrical distribution on both sides of the arc column center axis, and the axial current density and electron temperature gather and enhance in the opposite direction of the arc deflection, thereby significantly affecting the distribution of arc species.

Lifetime, size and emission of laser-induced plasmas for in-situ laser-induced breakdown spectroscopy on Earth, Mars and Moon

The spectroscopic technique of laser-induced breakdown spectroscopy (LIBS) is a powerful method to perform rapid chemical analysis of geologic samples with short measurement times and no need for sample preparation. After the ChemCam instrument aboard NASA’s MSL rover proved its suitability for space missions that explore planetary surfaces in 2012, the interest in LIBS instruments as payloads has grown and several subsequent missions have successfully used this technique since. The characteristics of a LIBS plasma depend on experimental and environmental parameters as well as on sample properties, including atmospheric conditions, laser irradiance and sample lithology. Consequently, LIBS instruments need to be designed and optimized specifically for each use case to maximize their science output. To aid in the development of new LIBS instruments for space exploration, we investigate the influence of atmospheric conditions, laser irradiance and sample lithology on the lifetime, size and emission of laser-induced plasmas. In our measurements, we use a plasma imaging setup with high temporal resolution of down to 2ns to investigate the evolution of the plasma from its ignition to its decay. We present a comparable data set recorded at terrestrial, Martian and airless atmospheric conditions, covering irradiances between 0.79GW/mmˆ2 and 1.43GW/mmˆ2 and samples with diverse properties, namely basalt and soapstone, as well as the lunar regolith simulants LHS-1 and LMS-1. Our measurements show the strong influence of atmospheric conditions on the plasma size and emission, while the lithologies and laser irradiances covered in this work play a minor role. This shows that instruments designed to work at certain atmospheric conditions can be used for a range of laser parameters and sample properties. Furthermore, we demonstrate that the decay of the plasma emission and the expansion of the plasma plume parallel to the sample surface can be described well by a power law and a drag model, respectively.

Design and fabrication of superhydrophobic microstructured grooved substrates to suppress the coffee-ring effect and enhance the stability of Sr element detection in liquids using LIBS.

A new technique has been developed to enhance the stability of laser-induced breakdown spectroscopy (LIBS) in the analysis of dry droplets by mitigating the coffee ring effect (CRE) on substrates with superhydrophobic microstructured grooves. The substrate was prepared from a laser-etched pure copper base, resembling the surface of a lotus leaf, creating a biomimetic superhydrophobic substrate. The superhydrophobic microstructured grooved substrate contained an array of dome-shaped cones with heights of approximately 140 μm and 100 μm, arranged in a periodic pattern of high-low-high. The superhydrophobic properties of the substrate not only evaporation-induced thermal capillary action but also initiated the Marangoni flow, which moves from the periphery to the center of the droplet as it evaporates. This flow mechanism effectively mitigated the CRE by transporting the analyte from the bottom edge of the droplet across its surface to the central peak. To assess how these superhydrophobic microstructured grooved substrates impede the formation of coffee rings, LIBS was deployed to analyze samples from both structured and unstructured grooved substrates. The results indicated that the relative standard deviation (RSD) of the spectral intensity for Sr I at 407.67 nm in substrates with a superhydrophobic microstructured groove edge length of 0.8 mm was 3.6%. In contrast, for the unstructured grooved substrate and a side length of 0.9 mm, the RSD was significantly higher at 25.4%. This research demonstrates that substrates with superhydrophobic microstructured grooves are capable of effectively mitigating the CRE. Additionally, the study examined how the dimensions of these grooves impact the plasma characteristics across two distinct configurations. Based on these observations, calibration curves for Sr were developed using substrates with groove side lengths of 0.6 mm and 0.8 mm. The performance of the superhydrophobic microstructured grooved substrate was satisfactory, exhibiting determination coefficients (R2) of 0.994 and 0.995 for the Sr element. The detection limits (LOD) were notably low at 0.16 μg mL-1 and 0.11 μg mL-1. The average relative standard deviations (ARSD) were 7.2% and 4.9%, respectively. These results demonstrate that the superhydrophobic microstructured grooved substrate effectively mitigates the CRE, thereby enhancing the detection sensitivity and prediction accuracy for heavy metals. This provides a robust reference for selecting platforms using LIBS technology in the pre-treatment process.

Measurements of N2 + ions in an inductively coupled plasma using saturated cavity ringdown spectroscopy

Abstract This paper presents a unique study of the bulk plasma characteristics in a low pressure inductively coupled nitrogen plasma. Saturated cavity ringdown spectroscopy (sat-CRDS) has been used to determine the absolute number densities and translational temperatures of N2 +(X, ν = 0). The effect of saturation is readily accounted for by using an effective saturation parameter, Seff , and determined by a simple method employing measurements at two different gain settings of the detection system. The appropriateness of this method is confirmed by comparison with fitting individual ringdown data using a time-dependent saturation parameter, S(t), within the local approximation model for sat-CRDS; the two methods are in excellent agreement in returning absolute number densities and translational temperatures. N2 +(X, ν = 0) number densities are determined across a matrix of pressure (10 − 100 mTorr) and rf power (200 − 400 W) conditions with maximum number densities of ca. 1.3 × 1010 cm−3 while translational temperatures range from 600 − 1500 K.

Influence of species kinetics on discharge characteristics in oxygen helicon plasma

Abstract Oxygen (O2) helicon plasmas in multiple wave modes were excited by a right-helical antenna with an upper metal endplate at low pressure. Mode transitions were observed at increasing input power or magnetic field, characterized by obvious jumps of plasma parameters. Blue Core appears at high magnetic fields (~700 G) and input powers (~1700 W), with a large radial gradient of plasma density, ion line intensity, and electron temperature. Emission spectra demonstrate that the blue lights originate from O II lines. We found that the intensity ratio of O II to O I of Blue Core in O2 is lower by one order than that in N2 or Ar despite their similar ionization rates and plasma densities in Blue Core area. A high-temperature B-dot probe together with a waveform fitting procedure was used to present the measured oscillating waveforms of m =+1 helicon waves, showing distinct wave structures of different eigenmodes. Cavity mode resonance is suggested to be responsible for the formation of standing waves of discrete eigenmodes. A pressure balance model was developed to estimate the species densities around the central area in different modes, showing massive dissociation of O2 molecules and high density of O atoms locally, so that O2 helicon plasma behaves a species feature of monatomic gas discharge. The obviously low intensity of O II lines compared to O I lines of Blue Core in O2 is related to the quite high excitation threshold of O+ ions (~30 eV) although electron density and temperature are relatively high. The combined effects of dispersed reaction energy distribution, massive molecule dissociation and negative ion creation are considered to be the main causes for requirement of much higher RF power and magnetic field for Blue Core formation in O2 helicon plasma than that in Ar. The calculated radial profile of power deposition and the captured plasma morphology confirm that the dominant central electron heating is the essential reason for the large radial gradients of plasma density and electron temperature which contributes to the serious neutral depletion and Blue Core formation.

Use of spectral transmittance model to improve the detection accuracy of chromium in soil

As a new quantitative analysis method for heavy-metal elements in soil, the main function of the polarization resolution model is to filter out the disturbance of other elements on the spectral signal of target plasma. In order to quantify the mechanism of improving detection performance, the spectral transmittance of plasma intensity in the polarization-resolved optical path has been derived, and the relationship between the intensity of polarization-resolved laser-induced breakdown spectroscopy (PRLIBS) and the characteristic peak wavelength has been defined. Using the spectral data in the wavelength range of 424.50–429.24 nm as the characteristic signal, a quantitative analysis method for detection of the Cr element in soil has been developed. The improvement of spectral intensity stability at the characteristic peak of Cr I 425.7 was analyzed, and the mechanism of enhancing the detection accuracy was elucidated. Research has shown that, based on the polarization characteristics of Cr element plasma, PRLIBS is not affected by the matrix effects of soil and characterizes the amplitude conversion from the reference concentration of Cr element to the plasma spectral intensity. The spectral transmittance of plasma spectra depends not only on the characteristic peak wavelength and complex refractive index of heavy-metal elements but also on the measurement conditions such as spatial geometric angles and reflectivity of the transmission medium.

A new optimization strategy, the influence of hollow electrode chamfers on the development of helium atmospheric pressure plasma jets

This work suggests applying chamfering treatment to the plasma generator of the empty electrode structure. Enhancing the electrodes’ physical structure can significantly improve plasma characteristics without requiring intricate control systems. Experiments have shown that changes in the electrode’s shape can lead to changes in the formation of the atmospheric pressure plasma jet. Specifically, our observations indicate that an increase in the chamfer radius leads to an increase in the ignition voltage and a greater density of reactive species inside the jet. We developed a multi-channel equivalent circuit model to describe the discharge process of a plasma jet. Then, using the mixed layer theory, we investigated the effect of the chamfer radius on the plasma jet. Our findings suggest that chamfering increases the effective discharge area, resulting in more discharge channels in the model. This leads to a higher density of reactive species. Additionally, chamfering improves the mixing of helium and air, increasing the concentration of N2 and O2. This consumes some of the avalanche electrons and raises the ignition voltages, ultimately enhancing the chemical reactivity of the plasma jet. This work provides new ideas for the optimization strategy of atmospheric pressure plasma radiation devices.

Low current iodine-fed hollow cathode discharge: insights from fluid model

Abstract As one of the fundamental components, hollow cathodes using noble gas propellant are widely used in electric thrusters. Iodine has become one of the ideal alternative propellants due to its economy and good chemical properties, while due to the complex reactions, characteristics and proper functioning of iodine-fed hollow cathodes are still unknown. Therefore, a model is needed to understand the physical-chemical process of the iodine-fed hollow cathode discharge. In this work, a self-consistent two-dimensional fluid model of the low-current iodine-fed hollow cathode discharge with detailed non-equilibrium plasma chemistry is developed and verified by the voltages of the keeper and anode obtained in the experiments. Simulations show that the electron impact ionization with iodine atoms dominates the discharge process as the density of iodine atoms is much higher than that of iodine molecules due to the electron impact dissociation and thermal dissociation. Moreover, the power balance analysis shows the heating of electrons contributed by the electric field mainly takes place near the keeper and the orifice. Ion current heating contributes significantly to the gas heating compared with the heating by the electron elastic collisions with I and I2 and the heat release or consumption during the neutral reactions. Furthermore, the influence of electronegativity on plasma characteristics is analysed. Simulations involving I− ions bring higher values of ionization degree, discharge power as well as maximum electron and gas temperatures compared with those without I−. This is similar to the differences in the plasma properties between the iodine-fed and xenon-fed hollow cathode to which the low ionization energy, large collision ionization cross-section and the electronegativity of iodine contribute together. In all, these findings can better predict the plasma behaviours in the iodine-fed hollow cathode discharge and may promote the development of the electric propulsion system using iodine propellant.

LIBS plasma diagnostics with SuperCam on Mars: Implications for quantification of elemental abundances

The Perseverance rover landed in Jezero Crater, Mars, in 2021 to explore an ancient delta for signs of past life and collect samples for a future Mars Sample Return Mission. SuperCam, onboard Perseverance, uses Laser Induced Breakdown Spectroscopy (LIBS) to quantify the elements in the rocks/soils encountered along the rover's traverse. LIBS is desirable for planetary science missions because of its effectiveness at a distance and with different target types (rock, soil, etc). However, decreased laser irradiance with distance and changing coupling efficiency in different targets could cause the physical conditions of the plasma plume to vary, with important implications for SuperCam's elemental calibration. This study examines the characteristics of laser-induced plasmas on Mars by estimating apparent temperature via the multiline Boltzmann plot method and electron density using Stark broadening of the H-α line. We find that apparent plasma temperatures do not decrease with distance or vary systematically with target type (rock vs soil). The variability in plasma temperatures seen on Mars is fully represented in the laboratory dataset used for SuperCam's elemental calibration, which suggests that our elemental calibration is likely robust against observed changes in apparent plasma temperature. These results imply that SuperCam can make reliable LIBS observations to at least 8 m. Estimated electron density is 1.4× higher in soils than rock targets, which is likely related to the dependence of the H-α line on topographic relief, a poorly understood mechanism which contributes to the difficulty of quantifying hydrogen abundance in Mars spectra.

Plasma synthesis and characteristics of nanocomposite coatings based on PVA and chitosan with incorporated nanoparticles for the healing of skin wounds

This study investigated the impact of new composites based on PVA and chitosan on wound healing in mice. Metal or metal oxide nanoparticles were synthesized without reagents by creating an impulse discharge between metal electrodes in a polymer dispersion. Polymer composites and coatings were then prepared using these nanoparticles. The composites were analyzed using various techniques, including UV spectroscopy, X-ray diffraction, scanning and transmittance electron microscopy, and infrared spectroscopy. The maximum concentration of nanoparticles in the composite was 3.5%. The average diameter of the nanoparticles was approximately 50-60 nm. The inclusion of Ag and ZnO nanoparticles accelerated the healing process by approximately 25%.

Review of Electrical Parameters Influence on Characteristics of Plasma Electrolytic Oxide Coating on Zircaloy

<p>Zircaloy-4 (Zr-4) is used as a fuel cladding material in Pressurized Water Reactor (PWR). Zr-4 as a cladding material works in extreme conditions in pressurized water up to 150 atm at 325 ˚C. In addition, the refuelling process in the reactor requires surface protection of the clay material to minimize corrosion and wear. One of the raising methods to enhance the corrosion resistance of the Zr-4 is by plasma electrolytic oxidation (PEO). Characteristics of the ceramic oxide layer produced by PEO are influenced by current density, type and composition of the electrolyte, and voltage mode. One of the challenges in the PEO development on the Zr-4 substrate is a high porosity with a range of 5%-20% and the low number (below 6%) of t-ZrO<sub>2</sub> phases in the inner and outer layers. Optimizing the electrical parameters is necessary to overcome this problem. The results of the literature study show that the cathodic current at the AC voltage plays an important role in determining the resulting plasma characteristics. Low duty cycle (cathodic current> 50%) produce plasma with high density, resulting in a low porosity layer. Oppositely, high duty cycle (cathodic current <50%) produced high content of t-ZrO<sub>2</sub> increase the mechanical resistance. Two-step PEO is beneficial in combining the low and high duty cycle to obtain the benefit of each step. </p>

Effect of input power on plasma expansion and ion acceleration in a radio-frequency plasma thruster

Exploring the physics of low pressure plasmas expanding in a diverging magnetic nozzle, and the resulting acceleration mechanisms, plays an important role in the development of a new-type of electrode-less plasma propulsion systems. This study discusses the effects of input power on plasma expansion and ion beam acceleration in a magnetic nozzle electrode-less plasma thruster. The experiments were conducted in a radio-frequency magnetic nozzle plasma device at The University of Auckland with four different power configurations PRF. Different plasma diagnostics were used to measure the characteristics of the plasma plume. A planar Langmuir probe was used to measure the floating potential and ion saturation current both in the plasma source and in the expansion chamber. The potential drop in the plasma source was obtained with an emissive probe. A retarding field energy analyser was employed to evaluate the local plasma and ion beam potentials, the ion energy distribution functions, and to estimate the ion beam speed in the expansion region. Measurements showed that, as expected, increasing the power input resulted in a higher plasma and supersonic ion density, while the ion beam speed did not increase further for PRF>100W. Interestingly, and contrary to the idealised physical model, the ion sonic transition did not occur at the magnetic nozzle throat, but instead close to the geometrical expansion point, i.e. near the interface between the source tube and the expansion chamber. This feature would result in a lower performance of the thruster given the reduced expansion ratio. An E-H mode change is also observed to occur in the device with increasing radio-frequency power that would help explain the different plasma characteristics observed at the 200W transition point.

Surface modification of fabrics using dielectric barrier discharge plasma for improved antifouling performance

Abstract Surface modification of fabrics is an effective way to endow them with antifouling properties while still maintain their key advantages like comfort, softness, and stretchability. Herein, an atmospheric pressure dielectric barrier discharge (DBD) plasma method is demonstrated for the processing of silk fabrics using 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDS) as the precursor. The results showed the successful grafting of PFDS groups on the surface of silk fabrics without causing damage. Meanwhile, the gas temperature is rather low during the whole processing procedure, suggesting the non-equilibrium characteristics of DBD plasma. The influence of processing parameters on fabrics was systematically investigated, like the PFDS concentration, plasma treatment time, and plasma discharge power. An optimum processing condition was determined to be PFDS concentration: 8 wt%, plasma processing time: 40 s, and plasma power: 11.87 W. However, with the prolonged plasma processing time or enhanced plasma power, the plasma-grafted PFDS films could be degraded. Further study revealed that plasma processing of silk fabrics with PFDS would lead to the change of their chemical composition and surface roughness. As a result, the surface energy of the fabrics was reduced, accompanied by the improved water and oil repellency properties as well as enhanced antifouling performance. Besides, the plasma-grafted PFDS films also had good durability and stability. By extending the fabrics to polyester and wool against different oil-/water-based stains, the DBD plasma surface modification technique demonstrated good versatility in improving the antifouling properties of fabrics. This work provides a guidance for the surface modification of fabrics using DBD plasma to confer them with desirable functionalities.

Evaluation of cfDNA fragmentation characteristics in plasma for the diagnosis of lung cancer: A prospective cohort study.

Lung cancer is one of the most prevalent cancers worldwide, yet only approximately 16% of patients are diagnosed in early stage, highlighting the urgent need for novel, highly accurate detection models. In our study, patients with suspected lung cancer or lung disease, as identified through radiographic imaging, along with healthy individuals, were consecutively recruited from Beijing Chest Hospital. Circulating free DNA (cfDNA) was extracted from plasma samples, and low-depth whole-genome sequencing was performed to identify fragmentomic features for model construction. A total of 265 participants were prospectively enrolled, comprising 124 lung cancer patients and 141 noncancer individuals. The model we developed was based on four cfDNA fragmentation characteristics, including 20-bp breakpoint nucleotides motif, fragmentation size coverage, fragmentation size distribution, and copy number variation. In an independent test cohort, the model achieved an area under the curve (AUC) of 0.861 (95% CI: 0.781-0.942) and demonstrated a sensitivity of 70% (95% CI: 53.5%-83.4%) at a specificity of 89.4% (95% CI: 76.9%-96.5%). Notably, the model was also effective in detecting early-stage cancer, with an AUC of 0.808 (95% CI: 0.69-0.925). In summary, our lung cancer detection model shows strong screening capabilities by leveraging four cfDNA fragmentation characteristics, exhibiting robust performance in early cancer diagnosis.

Effects of discharge parameters on plasma acceleration and transmission characteristics of a coaxial gun operated in gas-prefilled mode

The effects of discharge parameters on the discharge process and plasma transport characteristics of a coaxial gun in the gas-prefilled mode are studied. The plasma optical intensity and ejection velocity are measured by photodiodes, the optical emission spectrum is taken by a spectroscopic system, and the plasma evolution in the transport process is captured by a high-speed camera. The plasma acceleration characteristics under different discharge parameters show that the velocity and electron density of the ejection plasma are mainly determined by the pre-filled pressure and discharge current, which is consistent with the snowplow model. The kinetic energy of ejection plasma can be significantly increased by reducing the outer loop inductance, which is conducive to increasing the energy utilization efficiency. The time-varying images of plasma radiation and the plasma density at different transport locations illuminate the transmission characteristics of coaxial gun discharge plasma. The results show that the snowplow effect continues to play a role in the plasma transport process, and the plasma accumulation is induced by the combination of shock wave compression. The current-driven magneto hydrodynamics instability occurs during the transport process, and the luminous signal of the plasma current sheet oscillates periodically. In addition, the plasma impact effect is obvious and the gas retarding effect is enhanced with the increase in the gas pressure. These results give us a more comprehensive view of the coaxial gun discharge process and plasma transport and provide a certain reference for optimizing the parameters selection and physical design of coaxial gun discharge plasma characteristics.

Metabolomics identifies metabolite markers in plasma and extracellular vesicles within plasma in patients with asthma

BackgroundPlasma and extracellular vesicles (EVs) derived from plasma are important sources of information regarding individual health. Metabolomic analysis of plasma and EVs may provide new methods for predicting disease occurrence. This study aims to analyze the metabolomic characteristics of plasma and plasma EVs in asthma patients. MethodsPlasma samples were collected from healthy individuals and asthma patients. EVs were isolated from the plasma using ultracentrifugation. The isolated EVs were characterized by nanoparticle tracking analysis and flow cytometry. Metabolomic analysis was performed using a liquid chromatography-mass spectrometry platform. ResultsThis study successfully extracted EVs from plasma samples. Metabolomic analysis revealed that the composition of differential metabolites in the plasma and EVs of asthma patients was similar. KEGG pathway analysis indicated that the number of upregulated metabolic pathways enriched with differential metabolites in the plasma EVs of asthma patients was significantly greater than that in the plasma samples. Pathways associated with the onset of asthma included asthma, systemic lupus erythematosus, glycerophospholipid metabolism, and autophagy – other, primarily involving the following five metabolites: PS(18:1(9Z)/18:2(9Z,12Z)), PC(18:1(9Z)e/2:0), PS(24:1(15Z)/22:2(13Z,16Z)), PE(22:4(7Z,10Z,13Z,16Z)/22:5(4Z,7Z,10Z,13Z,16Z)), and PE(16:0/20:3(8Z,11Z,14Z)). Receiver operating characteristic analysis results suggested that these five differential metabolites may serve as potential biomarkers for asthma. ConclusionWe identified the metabolic characteristics of plasma and EVs in asthma patients, confirming that the metabolites in plasma EVs may serve as potential biomarkers for asthma. This finding not only enhances our understanding of the pathogenesis of asthma but also opens new avenues for targeted therapy.

Diagnostics of tin droplet-based laser produced plasma by triple Langmuir probe

Laser produced plasma extreme ultraviolet light source, as the exposure light source for next-generation lithography, faces urgent challenges due to its low conversion efficiency and significant debris contamination. Using a triple Langmuir probe, we conducted a study on the parameters and kinetic characteristics of tin droplet-based laser produced plasma that serves as extreme ultraviolet light source. In this paper, we report a design of triple Langmuir probe circuit based on the BWL (Bulk Wirewound Low-value) sampling resistor, which ensures that high-frequency signals remain undistorted during acquisition. Utilizing the “shadowgraph” method, we calculated the average deflection angles of droplet debris jets under different alignment conditions. Combining the diagnostic results from the probe, we found that the alignment accuracy between the laser and droplet directly influences the parameters of plasma. The parameters and kinetic characteristics of plasma were also diagnosed and analyzed at different angles and distances by moving the probe. Employing the triple Langmuir probe, measurements and analyses of laser produced plasma parameters and kinetic characteristics were achieved, providing a convenient method for diagnosing extreme ultraviolet lithography light sources. This work also offers an effective basis for optimizing the light sources.