REVIEW | doi:10.20944/preprints201809.0055.v1
Subject: Physical Sciences, Applied Physics Keywords: plasma membrane; spontaneous curvature; Helfrich energy; area difference elastic model; protein crowding; Deviatoric curvature
Online: 4 September 2018 (05:13:10 CEST)
In order to alter and adjust the shape of the membrane, cells harness various mechanisms of curvature generation. Many of these curvature generation mechanisms rely on the interactions between peripheral membrane proteins, integral membrane proteins, and lipids in the bilayer membrane. One of the challenges in modeling these processes is identifying the suitable constitutive relationships that describe the membrane free energy that includes protein distribution and curvature generation capability. Here, we review some of the commonly used continuum elastic membrane models that have been developed for this purpose and discuss their applications. Finally, we address some fundamental challenges that future theoretical methods need to overcome in order to push the boundaries of current model applications.
ARTICLE | doi:10.20944/preprints202212.0254.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: plasma membranes; secretion; ACBD3; KDEL receptor; Rab4; Rab11
Online: 14 December 2022 (09:12:18 CET)
KDEL receptor-1 maintains homeostasis in the early secretory pathway by capturing and retrieving ER-chaperones to the ER during heavy secretory activity. We have previously shown that a Golgi scaffolding protein (ACBD3) facilitates KDEL receptor localization at the Golgi via regulating cargo wave-induced cAMP/PKA-dependent signaling pathway. Unexpectedly, a fraction of the receptor is also known to reside in the plasma membrane as a stress response, although it is largely unknown exactly how KDEL receptor gets exported from the Golgi and travels to the PM. In this study, we sought to investigate the mechanism by which KDEL receptor gets exported from the Golgi en route to the PM and identified two crucial factors that greatly influence post-Golgi trafficking of KDEL receptor. We show here that ACBD3 depletion results in significantly increased trafficking of KDEL receptor to the PM via Rab4-positive tubular carriers emanating from the Golgi. Expression of constitutively activated Rab4 mutant (Q72L) increases surface expression of KDEL receptor up to 2~3-fold, whereas expression of GDP-locked Rab4 mutant (S27N) inhibits KDEL receptor localization to the PM. Importantly, KDELR trafficking from the Golgi to the PM is independent of PKA- and Src Kinase-mediated mechanism. Taken together, these results reveal that ACBD3 and Rab4-GTP are key players at the Golgi in regulating KDEL receptor trafficking to the cell surface.
REVIEW | doi:10.20944/preprints202207.0180.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: plasma membrane; membrane domains; nanodomains; neurotransmitter receptors; cannabinoids; acetylcholine receptor; cannabinoid receptor.
Online: 12 July 2022 (09:17:01 CEST)
Fifty years on from the classical fluid-mosaic model of Singer and Nicolson, current views of the plasma membrane portray a much more complex view of this interface region. Compartmentalization, together with transbilayer and lateral asymmetries, provide the structural foundation for functional specializations at the cell surface, including the active role of the lipid microenvironment in the modulation of membrane-bound proteins. The chemical synapse, the site where neurotransmitter-coded signals are decoded by neurotransmitter receptors, adds another layer of complexity to the plasma membrane architectural intricacy, mainly due to the need to accommodate a sizeable number of molecules in a minute subcellular compartment with dimensions barely reaching the micrometer. In this review, we discuss how Nature has developed suitable adjustments to accommodate different types of membrane-bound receptors and scaffolding proteins via membrane microdomains, and how this “efford-sharing” mechanism has evolved to optimize crosstalk or separation or coupling where/when appropriate. To this end, we use a fast ligand-gated neurotransmitter receptor, the nicotinic acetylcholine receptor, and a second-messenger G-protein coupled receptor, the cannabinoid receptor, as paradigmatic example.
ARTICLE | doi:10.20944/preprints202007.0059.v1
Subject: Biology And Life Sciences, Biophysics Keywords: plasma membrane; rafts; microemulsion; phase-separation; domain size
Online: 5 July 2020 (10:09:41 CEST)
It is widely, but not universally, believed that the lipids of the plasma membrane are not uniformly distributed, but that "rafts'' of sphingolipids and cholesterol float in a "sea'' of unsaturated lipids. The physical origin of such heterogeneities is often attributed to a phase coexistence between the two different domains. We argue that this explanation is untenable for several reasons. Further we note that the results of recent experiments are inconsistent with this picture. However they are quite consistent with an alternate explanation, namely that the plasma membrane is an emulsion of the two kinds of regions. To show this, we briefly review a simplified version of this theory and its phase diagram. We also explicate the dependence of the predicted domain size on four physical parameters. Among them are the spontaneous curvature of the membrane and its bending modulus and surface tension. Taking values of the latter two from experiment, we obtain domain sizes for several different cell types that vary from 58 to 88 nm.
ARTICLE | doi:10.20944/preprints202001.0062.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: C2 domain; E3 ubiquitin ligase; lipid binding; phosphoinositide; plasma membrane; smurf1; ubiquitin
Online: 8 January 2020 (04:34:28 CET)
SMAD ubiquitination regulatory factor 1 (Smurf1) is a Nedd4 family E3 ubiquitin ligase that regulates cell motility, polarity and TGFβ signaling. Smurf1 contains an N-terminal protein kinase C conserved 2 (C2) domain that targets cell membranes and is required for interactions with membrane-localized substrates such as RhoA. Here we investigated the lipid-binding mechanism of Smurf1 C2, revealing a general affinity for anionic membranes in addition to a selective affinity for phosphoinositides (PIPs). We found that Smurf1 C2 localizes not only to the plasma membrane but also to negatively charged intracellular sites, acting as an anionic charge sensor and selective PIP-binding domain. Site-directed mutagenesis combined with docking/molecular dynamics simulations revealed that the Smurf1 C2 domain loop region primarily interacts with PIPs and cell membranes, as opposed to the β-surface cationic patch employed by other C2 domains. By depleting PIPs from the inner leaflet of the plasma membrane, we found that PIP binding is necessary for plasma membrane localization. Finally, we used a Smurf1 cellular ubiquitination assay to show that the amount of ubiquitin at the plasma membrane interface depends on the lipid-binding properties of Smurf1. This study shows the mechanism by which Smurf1 C2 targets membrane-based substrates and reveals a novel interaction based on PI(4,5)P2 and PIP3 selectivity.
REVIEW | doi:10.20944/preprints202108.0411.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: abiotic stresses; gene-expression; genomics; ion homeostasis; plant growth and development; plasma membrane; sugar translocation
Online: 20 August 2021 (11:43:31 CEST)
Membrane transporters (MTs) are mainly localized at the plasma membrane (PM), tonoplast and vacuolar membrane (VM) of cells in all plant organs. Their work is to maintain the cellular homeostasis by controlling ionic movements across PM channels from roots to upper plant parts, xylem loading and remobilization of sugar molecules from photosynthesis tissues in the leaf (source) to roots, stem and seeds (sink) via phloem loading. The plant’s whole source-to-sink relationship is regulated by multiple transporting proteins in a highly sophisticated manner and driven based on different stages of plant growth and development (PG&D), and environmental changes. The MTs play a pivotal role in PG&D in terms of increased plant height, branches/tiller numbers, enhanced numbers, length and filled panicles per plant, seed yield and grain quality. Dynamic climatic changes disturbed the ionic balance (salt, drought and heavy metals) and sugar supply (cold and heat stress). Due to poor selectivity, some of the MTs also uptake toxic elements in the roots that negatively impact on PG&D, later on also exported to upper parts and then deteriorate the grain quality. As an adaptive strategy, in response to salt and HMs plants activated PM and VM localized MTs that export toxic elements into vacuole, and also translocate in the root’s tips and shoot. However, in case of drought, cold and heat stresses, MTs increased the water and sugar supply to all organs. In this review, we mainly reviewed recent literature from Arabidopsis, halophytes, and major field crops such as rice, wheat, maize and oilseed rape to argue on the global role of MTs in PG&D and abiotic stress tolerance. We also discussed the gene expression level changes and genomic variations within a species as well as within a family in response to developmental and environmental cues.
ARTICLE | doi:10.20944/preprints202309.0178.v1
Subject: Engineering, Mechanical Engineering Keywords: air plasma jet; PDMS plasma treatment; DBD plasma; plasma surface treatment
Online: 5 September 2023 (04:48:29 CEST)
PDMS samples may be used in various microfluidic applications by hydrophilizing their surfaces. This study examines the effects of air plasma jet (APJ) and dielectric barrier discharge (DBD) plasma on the surface hydrophilicity of polydimethylsiloxane. In order to increase the hydrophilicity of PDMS sample surfaces, two plasma sources including APJ and DBD were compared. Both DBD and APJ setups were measured for voltage and current, and their respective power was calculated and compared based on their characteristics. It is important to note that the electrical specifications of APJ and DBD were identical, and the source power rates for APJ and DBD plasma were 306W and 300W respectively. UV-vis spectroscopy was used to characterize the plasma, and an electrical characterization of the plasma's power supply was carried out. The effects of parameters such as the distance from the nozzle tip, the duration of the process, and the source voltage on the hydrophilicity of the surfaces during the treatment by APJ were also examined, and samples were then examined for a period of time to determine whether surface hydrophilicity was preserved. On the PDMS surface, a contact angle of about 5.1° was observed using short-term plasma treatments of 10 seconds. In the same conditions, the effect of DBD treatment was superior to that of APJ treatment.
COMMUNICATION | doi:10.20944/preprints202311.1205.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: plasma; linear plasma devices; plasma-surface interactions; vacuum; KAZ-PSI
Online: 20 November 2023 (07:25:27 CET)
The paper presents the results of the study of tungsten surface structure modification under helium plasma irradiation. It is revealed that during irradiation of samples, surface modification in the form of relief development as a result of irradiation is observed. X-ray phase analysis showed that no new phases of the W system were found after irradiation, only an increase in the intensity of diffraction lines was observed. There are significant differences in the microstructure of tungsten depending on the temperature of helium plasma irradiation in the above range. It is assumed that the cause of defects is the extremely low solubility of helium in tungsten. Metallographic analysis has shown that at irradiation of tungsten samples in regime 5 and 6 the degree of relief development is not high in comparison with the tungsten sample irradiated in regime 4. The greatest increase in roughness of the sample irradiated in regime 5 was determined, which is associated with the formation of small cracks, blisters and pores in the surface layer. At the same time, in the samples irradiated in regime 6, the surface of which is characterized by chaotically located protrusions and depressions of various shapes, the roughness parameter Ra was 0.0603 µm. It was found that at temperature regimes T = 1200 °C and T = 1500 °C the microhardness of tungsten increases by 11% and 10% respectively.
REVIEW | doi:10.20944/preprints201810.0061.v1
Subject: Physical Sciences, Fluids And Plasmas Physics Keywords: Plasma Generation Techniques, Applications of Plasma; Fusion technology; Plasma ion implantation and Deposition.
Online: 3 October 2018 (15:54:34 CEST)
Plasma being the fourth and most abundant form of matter extensively exists in the universe in the inter-galactic regions. It provides an electrically neutral medium of unbound negative and positive charged particles, which has been produced by subjecting air and various other gaseous mixtures to strengthen the electromagnetic field and by heating compressed air or inert gasses for creating negative and positive charged particles known as ions. Nowadays, many researchers are paying attention to the formation of artificial Plasma and its potential benefits for mankind. The literature is sparsely populated with the applications of Plasma. This paper presents specific methods of generation and applications of Plasma, which benefits humankind in various fields, such as in electrical, mechanical, chemical and medical fields. These applications include hydrogen production from alcohol, copper bonding, semiconductor processing, surface treatment, Plasma polymerization, coating, Plasma display panels, antenna beam forming, nanotechnology, Plasma Torch, Plasma pencils, low-current non-thermal Plasmatron, treatment of prostate cancer, Plasma source ion implantation, cutting by Plasma, Plasma etching, pollution control, neutralization of liquid radioactive waste, etc. Resultantly, worth of Plasma technology in the medical industry is increasing exponentially that is closing the gap between its benefits and cost of equipment used for generating and controlling it.
ARTICLE | doi:10.20944/preprints202003.0055.v1
Subject: Physical Sciences, Fluids And Plasmas Physics Keywords: Beam dumps; laser plasma accelerator; plasma beam dump
Online: 4 March 2020 (09:45:00 CET)
Beam dumps are indispensable components for particle accelerator facilities to absorb or dispose beam kinetic energy in a safe way. However, the design of beam dumps based on conventional technology, i.e. the energy deposition via beam-dense matter interaction, makes the beam dump facility complicated and large in size, partly due to nowadays’ high beam intensities and energies achieved. In addition, these high-power beams generate radioactive hazards, which need specific methods to deal with. On the other hand, the EuPRAXIA project can advance the laser-plasma accelerator significantly by achieving 1-5 GeV high quality electron beam in a compact layout. Nevertheless, the beam dump based on conventional technique will still produce radiation hazards and make the overall footprint less compact. Here, we propose to implement a plasma beam dump to absorb the kinetic energy from the EuPRAXIA beam. In doing so, the overall compactness of the EuPRAXIA layout will not be impacted, and the radioactivity generated by the facility can be mitigated. In this paper, results from particle-in-cell (PIC) simulations are presented for plasma beam dumps based on EuPRAXIA beam parameters.
ARTICLE | doi:10.20944/preprints202101.0068.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: cold plasma; plasma activated liquid; cancer cell; melanoma; fibroblast
Online: 5 January 2021 (10:04:48 CET)
Plasma medicine is a new field focusing on biomedical and clinical applications of cold physical plasmas, including their anticancer effects. Cold plasmas can be applied directly or indirectly as plasma activated liquids (PAL). The effect of plasma activated cell growth medium (PAM) and plasma activated phosphate buffered saline (PAPBS) were tested using a plasma pen generating streamer corona discharge in ambient air, on different cancer cell lines (melanoma A375, glioblastoma LN229 and pancreatic cancer MiaPaCa-2) and normal cells (human dermal fibroblasts HDFa). The viability reduction and apoptosis induction were detected in all cancer cells after incubation in PAL. In melanoma cells we focused on detailed insights to the apoptotic pathways. The anticancer effects depend on the plasma treatment time or PAL concentration. The first 30 minutes of incubation in PAL were enough to start processes leading to the cell death. In fibroblasts, no apoptosis induction was observed, only PAPBS, activated for longer time, slightly decreased their viability. Anticancer effects of PAM and PAPBS on cancer cells showed selectivity compared to normal fibroblasts, depended on correctly chosen activation time and PAL concentration. This selectivity, supported by optimum ratio of hydrogen peroxide and nitrites in PAL, is very promising for potential clinical applications.
REVIEW | doi:10.20944/preprints201809.0072.v1
Subject: Engineering, Mechanical Engineering Keywords: photo-catalysis, suspension plasma spray, thermal plasma, titanium oxide
Online: 4 September 2018 (15:08:47 CEST)
As a photo-catalytic titanium oxide film deposition process, thermal spray is hoped to be utilized practically on the condition that it is relatively easy to deposit anatase rich films. However, because of its high equipment and feedstock powder costs, it is very difficult to introduce thermal spray equipment into small companies. In this study, to develop a low cost thermal spray system, low power atmospheric suspension plasma spray equipment with titanium hydroxide suspension created by hydrolysis of titanium tetra iso butoxide using Ar, N2 as working gases. For avoiding sedimentation of the hydroxide particles in the suspension, mechanical milling of the suspension was conducted to create colloidal suspension before using it as feedstock. Moreover, an Ultrasonic wave container was used to keep the suspension particles moving while the spray process was conducted. After the film deposition, with As for the coating, anatase rich TiO2 ﬁlm could be obtained. For characterization of the film, microstructure observation by optical microscope and X-ray diffraction was carried out. Consequently, by creation of colloidal suspension, deposition could be conducted without sedimentation of the hydroxide particle in the suspension during operation. Besides, it was proved the film had enough photo-catalytic property to decolor methylene-blue droplet
ARTICLE | doi:10.20944/preprints201808.0483.v1
Subject: Physical Sciences, Nuclear And High Energy Physics Keywords: spectroscopy; plasma diagnostics
Online: 29 August 2018 (06:16:51 CEST)
We describe electron temperature measurements in the SSX MHD wind tunnel using two different methods. First, we estimate Te along a chord by measuring the ratio of the C_III 97.7 nm to CIV 155 nm line intensities using a vacuum ultraviolet monochrometer. Second, we record a biasing scan to a double Langmuir probe to obtain a local measurement of Te. The aim of these studies is to increase the Taylor state lifetime, primarily by increasing the electron temperature. Also, a model is proposed to predict magnetic lifetime of relaxed states and is found of predict the lifetime satisfactorily. Furthermore, we find that proton cooling can be explained by equilibration with the electrons.
ARTICLE | doi:10.20944/preprints202309.0129.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: plasma; plasma reactor; arc discharge; power supply; transformer; converter; cooperation
Online: 4 September 2023 (07:12:01 CEST)
Plasma generation by means of electrical discharge requires specialized power supply systems. The applicability of plasma for various plasma processes depends on its parameters, and these in turn depend on the parameters of the power supply systems. Arc plasma can be unstable, generating a lot of electromagnetic interference and overvoltage and overcurrent. The power system of a plasma reactor must guarantee good plasma control characteristics, be immune to disturbances and ensure good cooperation with the power grid. The article analyzes the cooperation of a three-phase plasma reactor, with gliding arc discharge, with a power supply system of a new type. This system integrates an AC/DC/AC converter with a five-column transformer of special design in a single device. Using the properties of magnetic circuits, it was possible to integrate the functions of ignition and sustaining the burning of the discharge in the reactor in a single transformer. Proper design of the transformer is crucial to achieve good cooperation of the AC/DC/AC converter with both the plasma reactor and the power supply network. The presented power supply design shows a number of positive features predisposing it to powering arc plasma reactors.
ARTICLE | doi:10.20944/preprints201907.0156.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: molecular spectroscopy; diatomic spectroscopy; Abel transform; plasma spectroscopy; laser-induced breakdown spectroscopy; laser-induced plasma; plasma dynamics
Online: 11 July 2019 (09:30:23 CEST)
Spatially resolved, line-of-sight measurements of aluminum monoxide emission spectra in laser ablation plasma are used with Abel inversion techniques to extract radial plasma temperatures. Contour mapping of the radially deconvolved signal intensity shows a ring of AlO formation near the plasma boundary with the ambient atmosphere. Simulations of the molecular spectra were coupled with the line profile fitting routines. Temperature results are presented with simultaneous inferences from lateral, asymmetric radial, and symmetric radial AlO spectral intensity profiles. This analysis indicates that we measured shockwave phenomena in the radial profiles, including a temperature drop behind the blast wave created during plasma initiation.
ARTICLE | doi:10.20944/preprints202311.0229.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: Cold atmospheric plasma; Dielectric Barrier Discharge; Plasma-activated liquids; Plasma medi-cine; Staphylococcus aureus; Escherichia coli; Candida albicans
Online: 3 November 2023 (10:14:16 CET)
In this study, Plasma-Activated Water (PAW) was synthesized using a coaxial Dielectric Barrier Discharge (DBD) reactor, benefiting from the elevated capacity of air-flow-assisted DBD discharges to enhance nitrogen-based species concentration. By manipulating operational parameters, including gas flow rate, activation time, and DI water volume, we achieved significant concentrations of Reactive Oxygen and Nitrogen Species (RONS). As a result, the PAW obtained displayed pronounced physicochemical attributes: a pH of 2.06, an ORP of 275mV, conductivity of 3mS/cm, and TDS of 1200 mg/L. A pivotal aspect of this research was the evaluation of the reactor's efficiency, as indicated by metrics like the specific input energy and ozone efficiency yield. The antimicrobial potential of the PAW was also assessed against pathogenic microbes, with remarkable reductions in viability for both Staphylococcus aureus and Escherichia coli (99.99%) and a more moderate decrease for Candida albicans (37%). These findings underscore the capability of the coaxial DBD reactor in crafting high-quality PAW with significant antimicrobial properties, necessitating further studies to validate its broad-spectrum and safe application.
ARTICLE | doi:10.20944/preprints202002.0259.v1
Subject: Physical Sciences, Fluids And Plasmas Physics Keywords: non-thermal atmospheric-pressure biocompatible plasma; diffusion; ozone species; plasma sterilizer
Online: 18 February 2020 (06:47:42 CET)
Medical institutions, where several patients are treated and medical workers engaged, are always exposed to secondary viral and bacterial infections. It is critical to prevent infection transmission by indirect as well as direct contact through air or splash. The infections of most diseases can be transmitted through the air. HEPA filters installed in air conditioning equipment are used to prevent infection transmission through air in medical institutions, but air circulation takes a long time in a large space. Virus and bacteria smaller than 0.3 μm cannot be removed by the HEPA filter; hence, those microbes remain alive throughout the air ventilation. A plasma sterilizer has the capability to provide environmental friendly sterilization by employing reactive oxide species and reactive nitrogen species at a low cost. We developed an excellent plasma sterilizer by using a non-thermal atmospheric-pressure biocompatible plasma (NBP). Ozone concentration in plasma sources has been derived by Kuhn et al. . The diffusion coefficients inside (D0) and outside (D1) the plasma sterilizer have been calculated to be 0.0641 m2 s-1 and 0.717 m2 s-1, respectively. To sustain high O3 concentrations over 121 ppm inside the plasma source and low O3 concentrations below 0.05 ppm outside the sterilizer, it is necessary to keep O3 concentrations at the exit of plasma sterilizer below 0.28 ppm. so that diffusion coefficient D1 has been designed to be as large as 11 times of D0.
ARTICLE | doi:10.20944/preprints201809.0070.v1
Subject: Engineering, Chemical Engineering Keywords: Plasma generation, non-thermal Plasma, pulsating DC power, Ozone, cost-improvement
Online: 4 September 2018 (14:56:31 CEST)
The objective of the prototype is to eliminate the polluting contamination of water sources, due to the leak of industrial waste without any kind of treatment, mainly generated by the industries and home sector. In this project, a prototype of water purification by plasma technology has been designed. The prototype will convert contaminated water into the plasma stream and eliminate the pathogens from the water by exposing it to ultraviolet radiation and plasma sterilisation. The polluted water will be accelerated at high speed using a water pump in order to convert it into a liquid-gas mixture for ease plasma generation. This process will be achieved when the electric supply from a source of alternating current (AC) is applied to the water by means of high voltage electrodes. After which, the mixture slows down to return into liquid form and the clean water is obtained. The whole process takes place without significantly raising the temperature also knows as non-thermal plasma. The device also has an automatic flow and pressure control system. Finally, a short feasibility study has been conducted on the water samples collected and report obtained from Chennai Metropolitan Water Supply and Sewage boards are reported. It has been concluded that this new plasma-based water treatment system will be more efficient and cheaper than the current wastewater treatment techniques and can be used in the future as the replacement of current secondary and tertiary treatments of industrial wastewater.
ARTICLE | doi:10.20944/preprints201807.0229.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: laser-plasma interactions; plasma dynamics and flow; hypersonic flows; emission spectra
Online: 13 July 2018 (10:16:46 CEST)
Micro-plasma is generated in ultra-high-pure hydrogen gas filled inside a cell at a pressure of (1.08 ± 0.033) × 105 Pa (810 ± 25 Torr) by using a Q-switched Nd:YAG laser device operated at 1064 nm wavelength and 14 ns pulse duration. Micro-plasma emission spectra of the hydrogen Balmer alpha line, Hα, are recorded with a Czerny-Turner type spectrometer and an intensified charge-coupled device. The spectra are calibrated for wavelength and corrected for detector sensitivity. During the first few tens of nanoseconds after initiating optical breakdown, significantly Stark-broadened and Stark-shifted Hα lines mark the well-above hypersonic outward expansion. The vertical diameters of the spectrally resolved plasma images are measured for time delays of 10 ns to 35 ns to determine expansion speeds of the order of 100 km/s to 10 km/s. For time delays of the order of 0.5 µs to 1 µs, the expansion decreases to the speed of sound of 1.3 km/s in the near ambient temperature and pressure hydrogen gas.
ARTICLE | doi:10.20944/preprints202306.1529.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: plasma electrolytic nitrocarburising; plasma electrolytic polishing; CP-Ti; friction; wear; microhardness; roughness
Online: 21 June 2023 (10:33:24 CEST)
The possibility of increasing wear resistance of the CP-Ti surface using a duplex surface treat-ment combining plasma electrolytic nitrocarburizing in a solution of ammonia, acetone and ammonium chloride and subsequent plasma electrolytic polishing is shown. Morphology and surface roughness, structure and microhardness of the modified layer were studied. The correla-tion of weight wear with hardness of diffusion layer at a low processing temperature and thick-ness of oxide layer is established – the largest decrease in weight wear occurs after nitrocarbu-rizing at 750 °C for 5 min (by 4.3 times). The possibility of an additional increase in wear re-sistance by subsequent polishing of the nitrocarburized CP-Ti surface at a voltage of 275–300 V for 3–5 min in chloride and fluoride electrolytes and 5–10 min in a sulfate electrolyte was re-vealed. Under these conditions, the hardened layer is preserved when the porous outer oxide layer is removed. According to the microtopology of the friction tracks, the wear mechanism is estimated as fatigue in dry friction and plastic contact.
COMMUNICATION | doi:10.20944/preprints202004.0126.v1
Subject: Biology And Life Sciences, Biophysics Keywords: Cold atmospheric Plasma; sterilization; Plasma-activated medium; Nitric oxide; Immunotherapy; COVID-19
Online: 8 April 2020 (11:34:11 CEST)
The recent pandemic has greatly stressed supply chains, treatment modalities, and medical resources. Cold atmospheric plasma (CAP) has been used for a wide range of applications in biomedical engineering due to its many components including electrons, charged particles, reactive oxygen species (ROS), reactive nitrogen species (RNS), free radicals, ultraviolet (UV) photons, molecules, electromagnetic fields, physical forces, and electric fields. In this manuscript, we develop CAP devices for COVID-19. Our manuscript indicates the advantages of highlydeployable CAP devices for both sanitation and treatment, without the need for supply chains of special consumables such as hand sanitizers and the like. We hope that this timely research will help engage the broader community of engineers that wish to help the medical community with this pandemic and to prevent and treat future outbreaks.
ARTICLE | doi:10.20944/preprints202305.1685.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: LIBS; microwave; isotope; plasma; emission
Online: 24 May 2023 (04:17:21 CEST)
Isotope detection and identification is paramount in many fields of science and industry, such as in the fusion and fission energy sector, in medicine and material science, and in archeology. The isotopic information provides fundamental insight on the research questions related to these fields as well as insight on product quality and operational safety. However, isotope identification with the established mass-spectrometric methods is laborious and requires laboratory conditions. In this work, Microwave-Assisted Laser-Induced Breakdown Spectroscopy (MW-LIBS) is introduced for isotope detection and identification utilizing radical and molecular emission. The approach is demonstrated with stable B and Cl isotopes in solids and H isotopes in liquid using emission from BO and BO2, CaCl, and OH molecules, respectively. MW-LIBS utilizes the extended emissive plasma lifetime and molecular emission signal integration times up to 900 s to enable use of low ~4 mJ ablation energy without compromising signal intensity and, consequently, sensitivity. On the other hand, long plasma lifetime gives time for molecular formation. Increase in the signal intensity towards the late microwave-assisted plasma was prominent in BO2 and OH emission intensities. As MW-LIBS is online-capable and requires minimal sample preparation, it is an interesting option for isotope detection in various applications.
ARTICLE | doi:10.20944/preprints202012.0231.v1
Subject: Chemistry And Materials Science, Chemical Engineering Keywords: Plasma, zinc oxide, photocatalysis, nanomaterials.
Online: 9 December 2020 (15:51:59 CET)
In this work, zinc oxide (ZnO) nanoparticles were modified in a circulating fluidized bed through argon and hydrogen (Ar-H) alternative-current (AC) arc plasma, which shows the characteristics of non-equilibrium and equilibrium plasma at the same time. In addition, a circulating fluidized bed with two plasma jets was used for cyclic processing. The catalytic degradation performance on Rhodamine B (Rh B) by Ar-H plasma modified ZnO and pure ZnO was tested in aqueous media to identify the significant role of hydrogen atoms in Rh B degradation mechanism. Meanwhile, the effects of plasma treatment time on the morphology, size and photocatalytic performance of ZnO were also investigated. The results demonstrated that ZnO after 20 minutes-treatment by Ar-H plasma showed Rh B photocatalytic degradation rate is ten times greater than that of pure ZnO, and the reaction follows a first-kinetics for the Rh B degradation process. Furthermore, the photocatalyst cycle experiment curve exhibited that the modified ZnO still displays optimum photocatalytic activity after five cycles of experiment. The improvement of photocatalytic activity and luminescence performance attributes to the significant increase of the surface area, and the introduction of hydrogen atoms on the surface also could enhance the time of carrier existence where the hydrogen atoms act as shallow donors.
REVIEW | doi:10.20944/preprints201907.0108.v1
Subject: Medicine And Pharmacology, Obstetrics And Gynaecology Keywords: endometriosis; circular; microRNA; diagnosis; plasma
Online: 8 July 2019 (06:10:33 CEST)
Plasma microRNAs are considered to be potential diagnostic biomarkers for endometriosis. Increasing evidence has shown that a huge amount of miRNAs are abnormally expressed in endometriosis plasma and play irreplaceable roles in diagnosis. The aim of the our study was to identify the differential expression of circular miRNA by reviewing the PubMed, ScienceDirect, and Cochrane databases between normal women and women with endometriosis and analyzing the miRNA data downloaded from the GEO database. Because of the differential miRNA expression in this review, we evaluated the diagnostic values of the differentially expressed miRNAs, particularly during the menstrual phases. According to the cut-off criteria with |log 2 FC|>1.0 and P < 0.05, 36 differentially expressed miRNAs were identified, including 13 upregulated miRNAs and 23 downregulated miRNAs. We developed miR-155, miR-574, miR-23a, and miR-520d via a Venn diagram. Functional enrichment analysis considered that the target miRNAs might be involved in various pathways related to endometriosis, including neurotrophin, Hippo, oocyte meiosis, ubiquitin mediated proteolysis, HTLV-Infection, FoxO, and Rap1 signaling pathways. CTNNB1, MYC, and ES R1 of transcription factors were related to the differentially expressed miRNAs. In summary, our study suggested that a four-miRNA could be included as a prognostic marker in endometriosis.
ARTICLE | doi:10.20944/preprints201807.0382.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: spinal cord injury; inflammation; plasma
Online: 20 July 2018 (12:49:20 CEST)
While over half of all spinal cord injuries (SCIs) occur in the cervical region, the majority of preclinical studies have focused on models of thoracic injury. However, these two levels are anatomically distinct—with the cervical region possessing a greater vascular supply, grey-white matter ratio and sympathetic outflow relative to the thoracic region. As such, there exists a significant knowledge gap in the secondary pathology at these levels following SCI. In this study, we characterized the systemic plasma markers of inflammation over time (1, 3, 7, 14, 56 days post-SCI) after moderate-severe, clip-compression cervical and thoracic SCI in the rat. Using high-throughput ELISA panels, we observed a clear level-specific difference in plasma levels of VEGF, leptin, IP10, IL18, GCSF, and fractalkine. Overall, cervical SCI had reduced expressions of both pro- and anti-inflammatory proteins relative to thoracic SCI, likely due to sympathetic dysregulation associated with higher level SCIs. However, contrary to the literature, we did not observe level-dependent splenic atrophy with our incomplete SCI model. This is the first study to compare the systemic plasma-level changes following cervical and thoracic SCI using level-matched and time-matched controls. The results of this study provide the first evidence in support of level-targeted intervention and also challenge the phenomenon of high SCI-induced splenic atrophy in incomplete SCI models.
ARTICLE | doi:10.20944/preprints201704.0126.v1
Online: 19 April 2017 (16:04:45 CEST)
A highly-integrated experimental system for plasma decomposition of fuels was built. Experiments were conducted and confirmed that macromolecular chain hydrocarbons were cracked by large-gap dielectric barrier discharge under the excitation of a microsecond-pulse power supply. Alkanes and olefins with a C atom number smaller than 10 as well as hydrogen were found in the cracked products of n-decane (n-C10H22). The combination of preheating and plasma decomposition had strong selectivity for olefins. Under strong discharge conditions, micromolecular olefins were found in the products. Moreover, there was a general tendency that micromolecular olefins gradually accounted for higher percentage of products at higher temperature and discharge frequency.
ARTICLE | doi:10.20944/preprints201704.0019.v1
Subject: Physical Sciences, Fluids And Plasmas Physics Keywords: TFTs; IGZO; flexible; plasma treatment
Online: 4 April 2017 (09:44:42 CEST)
Thin film transistors (TFTs) using In-Ga-Zn Oxide (IGZO) as active layer and the gate insulator was treated with NH3 plasma and N2O plasma, respectively, which is fabricated on flexible PI substrate in this work. The performance of IGZO TFTs with different plasma species and treatment time are investigated and compared. The experiment results show that the plasma species and treatment time play an important role in the threshold voltage, field-effect mobility, Ion/Ioff ratio, sub-threshold swing (SS) and bias stress stability of the devices. The TFT with a 10 seconds NH3 plasma treatment shows the best performance; specifically, threshold voltage of 0.34 V, field-effect mobility of 15.97 cm2/Vs, Ion/Ioff ratio of 6.33×107, and sub-threshold swing of 0.36 V/dec. The proposed flexible IGZO-TFTs in this paper can be used as driving devices in the next-generation flexible displays.
ARTICLE | doi:10.20944/preprints202310.0134.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: Rutherford backscattering; plasma focus; films; metals
Online: 3 October 2023 (09:22:30 CEST)
Thin Cu films with a thickness of ~0.5-2.5 mkm were obtained on the surface of Fe, V, and Ti metals using the Plasma Focus (PF) setup. The Cu film thickness was determined on an Ambios XP-200 profilometer. The distribution profiles of Cu, C, О2, N2 and H2 in initial metal samples: Fe, V, and Ti were studied by layer-by-layer analysis on a GDS 850A atomic emission spectrometer. It is shown that the distribution profile and the depth of occurrence of elements depend on the type of metal. Using the method of Rutherford Backscattering Spectrometry (RBS) of 4He+ ions, it was shown that for Cu atoms the depth of occurrence in Fe, V, and Ti, accordingly, is ~106, ~120, and ~160 nm. The depth of occurrence of C atoms in metals: Fe, V, and Ti is ~150, ~120, and ~200 nm, accordingly. From the data of layer-by-layer analysis on an atomic emission spectrometer in the initial samples of metals: Fe, V and Ti, a transition layer with a thickness of ~0.01, accordingly, was found; 0.5 and 1 mm. The presence of this layer is connected with the mechanical processing of metal samples, and the presence of a large number of admixtures in the thin layer of the metal. Thus, Cu atoms are located in the transition layer under the metal surface, which imparts adhesion and electrophysical properties of Cu films.
ARTICLE | doi:10.20944/preprints202308.1154.v1
Subject: Environmental And Earth Sciences, Waste Management And Disposal Keywords: Excess sludge; Discharge plasma; Thiosulfate; Disintegration
Online: 16 August 2023 (07:20:09 CEST)
Disposal and treatment of excess sludge is a huge problem in waste water treatment plants. Discharge plasma oxidation is an effective approach for sludge dewatering and digestion. In this study, the excess sludge disintegration by non-thermal discharge plasma coupled with thiosulfate (TSA) was investigated. The soluble chemical oxygen demand (SCOD) increased to 404.93 mg L-1 after 20 min of single discharge plasma treatment, and it further increased to 549.08 mg L-1 after adding 15 mmol L-1 of TSA; the water content of filter cake also further decreased in the presence of TSA. There existed an appropriate TSA dosage. In the discharge plasma coupled with TSA system, reactive oxygen species (·OH and ·O2-) were produced and played important roles in sludge disintegration. The addition of TSA promoted the production of ·OH. These reactive oxygen species destroyed the floc structures and promoted the transformation of organic substances, leading to reduction in average size of sludge flocs. The ratio of soluble extracellular polymer substances (S-EPS) was enhanced, while the ratio of tightly bound fraction was reduced after treatment. Thus, discharge plasma coupled with TSA promoted the lysis of microbial cells and released intracellular organic matter and bound water, finally improving sludge dewaterability.
COMMUNICATION | doi:10.20944/preprints202305.0314.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: liquid profiling; plasma; methylation; mSHOX2; mPTGER4
Online: 5 May 2023 (07:23:15 CEST)
Notwithstanding the fact that there is some improvement for an earlier detection of patients with lung cancer, the majority of them still present with a late-stage disease at the time of diagnosis. Next to the most frequently used factors affecting the prognosis of lung cancer patients (stage, performance and age) the recent application of biomarkers obtained by liquid profiling gained more acceptance. In our study we aimed to answer these questions: i) is the quantification of free-circulating methylated PTGER4 and SHOX2 plasma DNA an useful method for the therapy monitoring and is this also possible for patients treated with different therapy regimens?, and ii) is this approach possible when blood drawing tubes are used which allow for a delayed processing of blood samples? Baseline values for mPTGER4 and mSHOX2 do not allow for a clear discrimination between different response groups. In contrast the combination of the methylation values for both genes show a clear difference between responders vs non-responders at the time of re-staging. Additionally, blood drawing into tubes stabilizing the sample give researchers more flexibility.
COMMUNICATION | doi:10.20944/preprints202212.0558.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: SMN; SMA; plasma membrane; ABCA1; cholesterol
Online: 29 December 2022 (09:13:39 CET)
The deficiency of Survival Motor Neuron (SMN) protein causes Spinal Muscular Atrophy (SMA), a rare neuromuscular disease that affects different organs. SMN is a key player in RNA metabolism regulation. An intriguing aspect of SMN function is its relationship with plasma membrane-associated proteins. Here, we provide a first demonstration that SMN affects the ATP-binding cassette transporter A1, (ABCA1), a membrane protein critically involved in cholesterol homeostasis. In human fibroblasts, we showed that SMN associates to ABCA1 mRNA, and impacts its subcellular distribution. Consistent with the central role of ABCA1 in the efflux of free cholesterol from cells, we observed a cholesterol accumulation in SMN-depleted human fibroblasts. These results were also confirmed in a SMA type I patient-derived fibroblasts. These findings not only validate the intimate connection between SMN and plasma mem-brane-associated proteins, but also highlight a contribution of dysregulated cholesterol efflux in SMA pathophysiology.
ARTICLE | doi:10.20944/preprints202207.0208.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: plasma; biomarker; proteomics; 2DE; proteoform; pattern
Online: 14 July 2022 (10:14:23 CEST)
Cancer is a complex systemic disease that changes the entire proteome. The analysis of this transformation makes it possible to determine tumor markers, that is, the most characteristic biomacromolecules produced by tumor cells. Here, the question of finding ideal tumor markers, which should be sensitive, specific, and reliable, is an acute issue. Unfortunately, none of the tumor markers, even those used in the clinic, has all these characteristics. Despite this, many tumor markers have demonstrated excellent clinical relevance for monitoring the effectiveness of different treatments for cancer patients. The use of markers also aids in the early detection of cancer recurrence and prognosis. Therefore, the situation in this area can be improved in two ways – by attempting to find an ideal single tumor marker or generating panels of different markers. In both cases, proteomics certainly plays a major role. Human plasma is one of the most popular samples as it is commonly collected in the clinic and provides noninvasive, rapid analysis for any type of disease including cancer. Many efforts have been applied in searching for “ideal” tumor markers digging very deep plasma proteome. There is a line of evidence that the most abundant, so-called “classical plasma proteins”, may be used to generate a tumor biomarker profile. To be comprehensive these profiles should have information not only about protein levels but proteoform distribution for each protein. Initially, the profile of these proteins in norm should be generated. Here, we present data about these profiles generated by two-dimensional electrophoresis with the following mass-spectrometry and immunodetection.
ARTICLE | doi:10.20944/preprints202005.0233.v2
Subject: Physical Sciences, Astronomy And Astrophysics Keywords: Supernova; Plasma; Gravitational Lens; Einstein Cross; Hubble Constant; Hubble Tension
Online: 24 May 2022 (13:24:51 CEST)
Simulations based on Supernova (SN) observations predict several galactic SN explosions (SNe) occur every century. Unlike SNes within the Interstellar Medium (ISM) where ambient gas generally absorbs blast waves within a million years, SNes occurring in a rarified environment outside of the (ISM) generate blast waves which remain in a high velocity free expansion phase for more extended periods. The SN blast wave forms an expanding spherical shell and when multiple blast waves intersect, the overlapping region naturally takes the form of a ring, an arc, or an Einstein Cross structure. The analysis shows the high velocity plasma establishes a medium with permeability which drives the index of refraction greater than 1. As a result, when a shock discontinuity forms in the overlapping region, light is reflected from the host galaxy which exposes the intersecting blast wave regions. The expanding shells are shown to induce an achromatic redshift to the reflected light consistent with those measured for gravitational lenses. Further, it is shown that a Hubble equation for a blast wave around the Milky Way Galaxy can be parameterized to align with measured redshifts of extragalactic light fields over a wide range of distances.
ARTICLE | doi:10.20944/preprints202001.0337.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: slag; basicity; hydrogen plasma; smelting reduction; iron oxide; plasma arc; hydrogen utilisation; degree of reduction; hematite
Online: 28 January 2020 (10:33:33 CET)
Replacing carbon by hydrogen is a huge step towards reducing CO2 emissions in the iron- and steel-making industry. The reduction of iron oxides using hydrogen plasma smelting reduction as an alternative to conventional steel-making routes has been studied at Montanuniversitaet Leoben, Austria. The aim of this work was to study the slag formation during the reduction process and the reduction behaviour of iron oxides. Furthermore, the reduction behaviour of iron ore during continuous feeding was assessed. Mixtures of iron ore and calcined lime with a basicity of 0, 0.8, 1.6, 2.3, and 2.9 were melted and reduced by hydrogen. The off-gas composition was measured during the operations to calculate the process parameters. The reduction parameters, namely the degree of reduction, degree of hydrogen utilisation, produced iron, and slag, are presented. The results of the batch-charged experiments showed that at the beginning of the reduction process, the degree of hydrogen utilisation was high, and then, it decreased over the operation time. In contrast, during the continuous-feeding experiment, the degree of hydrogen utilisation could be kept approximately constant. The highest degrees of reduction and hydrogen utilisation were obtained upon the application of a slag with a basicity of 2.3. The experiment showed that upon the continuous feeding of iron ore, the best conditions for the reduction process using hydrogen could be applied.
ARTICLE | doi:10.20944/preprints202009.0397.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: dual frequency comb spectroscopy; mid-infrared absorption and dispersion spectroscopy; electrical discharge plasma; time-resolved plasma kinetics
Online: 17 September 2020 (11:03:42 CEST)
Conventional mechanical Fourier Transform Spectrometers (FTS) are able to simultaneously measure absorption and dispersion spectra of gas-phase samples. However, they usually need very long measurement times to achieve time-resolved spectra with a good spectral and temporal resolution. Here, we present a mid-infrared dual-comb-based FTS in an asymmetric configuration, providing broadband absorption and dispersion spectra with a spectral resolution of 5 GHz, a temporal resolution of 20 μs, and a total measurement time of a few minutes. We used the dual-comb spectrometer to monitor the reaction dynamics of methane and ethane in an electrical plasma discharge. We observed ethane/methane formation as a recombination reaction of hydrocarbon radicals in the discharge in various static and dynamic conditions. The results demonstrate a new analytical approach for measuring fast molecular absorption and dispersion changes and monitoring fast dynamics of chemical reactions, which can be interesting for chemical kinetic research and particularly for the combustion and plasma analysis community.
ARTICLE | doi:10.20944/preprints201904.0261.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: hydrogen plasma; smelting reduction; iron oxide; plasma arc; degree of hydrogen utilization; degree of reduction; hematite; basicity
Online: 23 April 2019 (13:16:39 CEST)
The development of hydrogen plasma smelting reduction as a CO2 emission-free steel-making process is a promising approach. This study presents a concept of the reduction of hematite using hydrogen thermal plasma. A laboratory scale and pilot scale hydrogen plasma smelting reduction (HPSR) process are introduced. To assess the reduction behavior of hematite, a series of experiments has been conducted and the main parameters of the reduction behavior, namely the degree of hydrogen utilization, degree of reduction and the reduction rate are discussed. The thermodynamic aspect of the hematite reduction is considered and the pertinent calculations have been carried out using FactSageTM 7.2. The degree of hydrogen utilization and the degree of reduction were calculated using the off-gas chemical composition. The contribution of carbon, introduced from the graphite electrode, ignition pin and steel crucible, to the reduction reactions was studied. The degree of reduction of hematite, regarding H2O, CO and CO2 as the gaseous reduction products, is determined. It is shown that the degree of hydrogen utilization and the reduction rate were high at the beginning of the experiments, then decreased during the reduction process owing to the diminishing of iron oxide. Conducting experiments with the high basicity of slag B2=2 led to a decrease of the phosphorus concentration in the produced iron.
REVIEW | doi:10.20944/preprints201805.0459.v1
Subject: Physical Sciences, Astronomy And Astrophysics Keywords: white dwarfs; burning in stars; plasma diagnostics; atomic spectra; plasma spectroscopy; laser spectroscopy; laser-induced breakdown spectroscopy
Online: 31 May 2018 (05:13:00 CEST)
This work communicates a review on Balmer series hydrogen beta line measurements and applications for analysis of white dwarf stars. Laser-induced plasma investigations explore electron density and temperature ranges comparable to white dwarf star signatures such as Sirius B, the companion to the brightest star observable from the earth. Spectral line shape characteristics of the hydrogen beta line include width, peak separation, and central dip-shift, thereby providing three indicators for electron density measurements. The hydrogen alpha line shows two primary line-profile parameters for electron density determination, namely, width and shift. Both Boltzmann plot and line-to-continuum ratios yield temperature. The line-shifts recorded with temporally- and spatially- resolved optical emission spectroscopy of hydrogen plasma in laboratory settings can be larger than gravitational redshifts that occur in absorption spectra from radiating white dwarfs. Published astrophysical spectra display significantly diminished Stark or pressure broadening contributions to red-shifted atomic lines. Gravitational redshifts allow one to assess the ratio of mass and radius of these stars, and subsequently, the mass from cooling models.
COMMUNICATION | doi:10.20944/preprints202310.0122.v1
Subject: Environmental And Earth Sciences, Space And Planetary Science Keywords: low-latitude ionosphere; LQP echoes; plasma instability
Online: 3 October 2023 (10:50:47 CEST)
The low-altitude quasi-periodic (LQP) E-region echoes observed with the upgraded HCOPAR located in Hainan Island of China (19.5°N, 109.1°E) are presented. With the interferometry technique, the interferometry equations can be developed to investigate the structures of the irregularities. The results show that the plasma structures of the LQP echoes with negative slope mainly drift southwestward almost horizontally, but they also drifted southeastward in some striations. According to the movement of the plasma structures, we find strong wind shear in the region where the LQP echoes are produced. Meanwhile, The periodicity of the LQP echoes may be related to the strength of the wind shear. It is proposed that the plasma structures are most likely produced by the Kelvin-Helmholtz instability.
ARTICLE | doi:10.20944/preprints202307.0015.v1
Subject: Environmental And Earth Sciences, Sustainable Science And Technology Keywords: PFCs; Plasma-wet Scrubber; DRE; By-product
Online: 3 July 2023 (08:26:30 CEST)
Perfluorinated compounds (PFCs) are used in the manufacturing process of the semiconductor and display industries, and the need for emission reduction is growing as a greenhouse gas with a very large global warming potential. The decomposition characteristics of etch type and water film (WF) type plasma-wet scrubbers were investigated. The PFCs used in the study were CF4, SF6, NF3, CHF3, C2F6, C3F8, and C4F8, and the destruction removal efficiency (DRE) and by-product gas generation rate according to the changes in the parameters (total flow rate and power) of the plasma-wet scrubber were confirmed. When the total flow rate was 100 L/min and the measured maximum power (11 kW), the reduction efficiency of CF4 in the etch type was 95.60 % and the DRE of other PFCs was 99.99 %. And, in the WF type, the DRE of CF4 was 90.06 %, that of SF6 was 96.44 %, and that of other PFCs was 99.99 %. When the total flow rate was 300 L/min and 11 kW, the DRE of SF6 in the etch type was 99 %, and the DRE of NF3, CHF3, C2F6, C3F8, and C4F8 were 99.80 %, 95.34 %, 85.38 %, 88.49 %, and 98.22 %, respectively. And, in the WF type, the DRE of SF6 was 94.39 %, and the DRE of NF3, CHF3, C2F6, C3F8, and C4F8 were 99.80 %, 95.34 %, 85.38 %, 88.49 %, and 98.22 %, respectively. The by-product gas generation rate was significantly lower in the WF type.
COMMUNICATION | doi:10.20944/preprints202305.1924.v1
Subject: Engineering, Other Keywords: NiTi coating; Graphite substrate; Microstructural; Plasma spraying
Online: 26 May 2023 (10:52:40 CEST)
In this study, Ni50Ti50 powder was coated on the surface of graphite substrate (C) by plasma spraying process using a radio frequency inductively coupled plasma reactor. The coating was carried out by using 12- and 9-kW power under Ar atmosphere. The cross-section of coating layers and the surface were examined with SEM, EDX, XRD analysis and microhardness test. The thickness and quality of the coating increased with input power. Many pores were detected in the cross-sectional surface areas. Higher input power caused a better coating layer in NiTi alloy. The hardness of the coating layer decreases with higher input power.
ARTICLE | doi:10.20944/preprints202305.1121.v1
Subject: Chemistry And Materials Science, Ceramics And Composites Keywords: tungsten carbide; spark plasma sintering; diffusion; carbon
Online: 16 May 2023 (07:54:18 CEST)
The research results conducted on binderless tungsten carbide (WC) ceramics obtained by Spark Plasma Sintering (SPS) of WC powders with different average particle sizes (0.095, 0.8, 3 μm) are presented. Nonuniform distribution of crystalline phases and microstructure of the WC ceramics was studied using layer-by-layer XRD analysis and SEM. Surface layers of the WC-based ceramics are characterized by nonuniform distribution of W2C crystalline phase and grain sizes, including the appearance of abnormally large grains. Thickness of the nonuniform layer was at least 50 μm. The effect under study is associated with an intense carbon diffusion from graphite foil. On the one hand, this contributed to a decrease in the intensity of W2C phase particle formation, which is transformed into α-WC phase due to the carbon. On the other hand, it caused abnormal grain growth in the layer where the carbon diffused. The obtained value of the carbon diffusion depth exceeds the values known from the literature (up to 1 μm in the case of volume diffusion even at temperature of 2370℃ and exposure time of ~ 60 h). The use of boron nitride (BN) as a protective coating on graphite mold parts did not prevent the formation of nonuniform layer on the ceramic surface.
REVIEW | doi:10.20944/preprints202305.0365.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: silicon; thin-films; nanostructures; growth; plasma-assisted
Online: 5 May 2023 (11:41:55 CEST)
Silicon-based thin-films and nanostructures are of paramount importance in a wide range of applications, including microelectronics, photovoltaics, large area sensors, as well as biomedicine. The wide accessibility of silicon and its relatively low cost have driven a continuous improvement of the technology based on this element. Plasma technology has been widely used for the synthesis of coatings and nanostructures based on silicon. Moreover, it has given a fundamental contribution for continuously improving the control of the physicochemical properties of silicon-based materials, and for allowing the synthesis of nanometric structures with well-defined shape and morphology. In this work, we have reviewed the most interesting developments of plasma-assisted processed for the synthesis of Si-based materials, both inorganic and organic, in the last five years. A special attention has been given to the new techniques, or modifications of already existing ones, that open new possibilities for the synthesis of materials with new properties, as well as nanostructures with novel characteristics.
ARTICLE | doi:10.20944/preprints202304.0459.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: Deucravacitinib; HPLC-MS/MS; Psoriasis; Human plasma
Online: 18 April 2023 (02:51:35 CEST)
Plaque psoriasis is a common, long-lasting illness that affects the immune system and causes significant negative impacts on a patient's physical health, well-being, and ability to work effectively. Deucravacitinib (DEU) is the first oral medication used in the treatment of plaque psoriasis, a chronic skin condition that causes red, scaly patches on the skin. DEU is a type of medication called an oral Janus kinase (JAK) inhibitor, which works by blocking specific enzymes that play a role in the inflammation and immune response associated with psoriasis. Therefore, a quick, easy, novel, reliable, sensitive, and straightforward Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) approach was used to analyse DEU in plasma samples. The LC-MS/MS method for the determination of DEU in human plasma was based on using trimethoprim as an internal standard (IS). The separation of DEU and IS was carried out via liquid-liquid extraction (LLE). The isolated substances were then subjected to the chromatographic system using the ACE-C18 column (4.6x100 mm, 5 µm). The mobile phase employed consisted of methanol and a solution of 2 mM ammonium formate (80:20 v/v, respectively). The flow rate used was set at 0.9 mL min-1. The creative strategy was performed by running an ABSCIEX API 4000 mass spectrometer with an electron spray ionization source in Multiple Reaction Monitoring (MRM) modes. The ion transitions m/z 426.3 358.2 was used for DEU quantitation, while the ion transitions m/z 291.1 261.1 was used for trimethoprim quantitation. The accuracy, precision, linearity, recovery, and selectivity of DEU were deemed acceptable when validated for a concentration range between 0.500 to 601.050 ng/mL, utilizing a weighting factor of 1/x2.
ARTICLE | doi:10.20944/preprints202208.0240.v1
Subject: Physical Sciences, Nuclear And High Energy Physics Keywords: polarized ion beam; polarimetry; laser-plasma acceleration
Online: 12 August 2022 (12:51:46 CEST)
We present a compact polarimeter for 3He ions with special emphasis on the analysis of short-pulsed beams accelerated during laser-plasma interactions. We discuss the specific boundary conditions for the polarimeter, such as the properties of laser-driven ion beams, the selection of the polarization-sensitive reaction in the polarimeter, the representation of the analyzing-power contour map, the choice of the detector material used for particle identification, as well as the production procedure of the required deuterated foil-targets. The assembled polarimeter has been tested using a tandem accelerator delivering unpolarized 3He ion beams, demonstrating good performance in the few-MeV range. The statistical accuracy and the deduced figure-of-merit of the polarimetry are discussed, including the count-rate requirement and the lower limit of accuracy for beam-polarization measurements at a laser-based ion source.
ARTICLE | doi:10.20944/preprints202207.0416.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: biofouling; deposition; hydrophobic; plasma treatment; PTFE; stickiness
Online: 27 July 2022 (08:53:19 CEST)
The spray drying process causes the buildup of an unspecified and unique pattern of wall deposits on the wall. The powder recovery of fruit juice by spray dryer is associated with stickiness problems because of the nature of food which contains low molecular weight sugars and organic acids, which have a low glass transition temperature (Tg). The surface properties of oxygen plasma treated-PTFE substrate were evaluated by using the different parameters of Plasma Enhanced Chemical Vapour Deposition (PECVD) prior to spray drying analysis. In this study, the fabrication method of nearly perfect superhydrophobic surfaces through plasma treatment with oxygen gas was generated and utilized. The plasma-treated PTFE were deposited from a fixed flow rate of oxygen gas with 30 cm3/min by varying the deposition time from 1 to 15 minutes to induce the hydrophobic surface of the PTFE substrate. The characterization techniques used to determine the morphology and chemical bonding of the substrate are field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The hydrophobicity of the glass samples was determined by the water droplet contact angle. Sample prepared at radio frequency (RF) power of 90W for 15 minutes duration of treatment time showed porous and spongy like microstructure which correlates with the best performance of a good contact angle which creates the superhydrophobicity regime (171o). Surface morphology analysis using scanning electron microscopy (SEM) showed changes in its roughness in the surface-treated glass substrate. The success of this method produced a huge potential for solving most of the food processing issues which relate to biofouling (e.g., powder stickiness) that would otherwise struggle to improve high productivity and recovery.
ARTICLE | doi:10.20944/preprints202203.0044.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: energetic material; plasma; detonation; electromagnetism; high temperature
Online: 2 March 2022 (10:39:48 CET)
In the process of deflagration of energetic materials, strong electromagnetic radiation is to be generated, which causes the surrounding electronic equipment to fail to work normally. To solve this problem, it is necessary to clarify the mechanism of electromagnetic radiation generated by energetic materials. The mechanism of plasma changed by the deflagration of energetic materials is an important topic in the aerospace and geophysics fields. The academic community holds two main viewpoints on the mechanism of electromagnetic radiation generated by energetic materials: one is that the solid material is squeezed and deformed during the deflagration of energetic materials, and the charges of different polarities rub in space to form effective electric dipoles, which eventually generate electromagnetic radiation. Another view is that the deflagration of energetic materials causes the temperature of the medium to rise sharply, and bremsstrahlung is formed during the compression and diffusion of the high-temperature wave front, resulting in the generation of electromagnetic radiation. This paper, based on theoretical analysis and experimental data, holds the view that electromagnetic radiation is generated by the high-temperature thermal effect. It studies the relationship between temperature and electromagnetic radiation and obtains quantitative analysis conclusions.
ARTICLE | doi:10.20944/preprints202110.0439.v2
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: geopolymer; plasma; surface treatment; fly ash; wettability
Online: 1 March 2022 (12:42:26 CET)
This paper deals with investigation of changes in geopolymer wettability with increasing mass fraction of high-carbon fly ash and surface treatment by cold atmospheric plasma (CAP). In this study, multiple samples of geopolymers were prepared, including those with 5% and 10% of high-carbon fly ash from coal-fired power station. Wettability of samples was then measured before and after plasma treatment, both on surface and cut surface. While addition of fly ash only had low effect on the wettability, as in most cases, it only lowered the initial contact angle without speeding up the speed of soaking for compact geopolymer and actually slowed the soaking for foamed geopolymer, plasma treatment had significant impact and made the geopolymer hydrophobic.
ARTICLE | doi:10.20944/preprints202202.0299.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: aluminum nitride; plasma chemical synthesis; nitride ceramics
Online: 23 February 2022 (15:01:18 CET)
A technology for obtaining nanosized aluminum nitride powder by plasma-chemical synthesis is presented. Nitrogen gas (N2), melamine (C3H6N6) and ammonia (NH3) were used as a source of nitrogen. Aluminum powder of different fractions was used as a source of aluminum. The influence of the nitrogen source, the height of the injector, and the input power of the plasma equipment on the synthesized aluminum nitride powder is shown. The resulting aluminum nitride powder has a size d90=60 nm. The parameters of aluminum nitride synthesis did not in any way affect the granulometric composition of the synthesized powder materials. It was found that, due to the high binding energy, the nitrogen molecule (N2) reacts poorly with aluminum powder particles, as a result a mixture of nitrogen and ammonia gases was used in a ratio of 70/30 (mol.%) for aluminum nitride synthesis.
ARTICLE | doi:10.20944/preprints202106.0583.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: CNC Machine Tool; Plasma; Surface Heat Treatment
Online: 23 June 2021 (12:47:11 CEST)
The mechanical engineering requires heat treatment after rough machining to reach the mechanical strength, but the heat treatment can induce workpiece deformation, so that the workpiece cannot be reworked. In this study, the plasma was integrated with a lathe, and the on line heat treatment was performed to achieve the mechanical strength and hardness, so as to reduce the machining process and handling. However, for on line heat treatment, it is important to study the machine and plasma parameters of the lathe and plasma, and the research method is used eventually to optimize the process, reduce the machining cost and machining error. The variable factors in surface on line real-time heat treatment are revolution, feed rate and current, the objective function is the hardness of mechanical properties. In the screening experiment, the interaction of factors was discussed using full factorial experiment. The Central Composite Design was combined with the Lack-of-Fit test for optimization experiment, the R2 coefficient was used to determine whether the regression model is appropriate. The optimum parameters were derived from the contour diagram and response surface diagram. The experimental results show that the significant factors include revolution, feed rate and current, the optimum parameters include revolution 168rpm, feed rate 0.068mm/rev and current 86A. The experimental results of optimum parameters show that the surface hardness is increased from 306HLD to 806HLD, the surface hardening effect is enhanced by 163%, so the on line real-time heat treatment equipment has a best hardening effect.
ARTICLE | doi:10.20944/preprints202005.0250.v8
Subject: Physical Sciences, Acoustics Keywords: Plasma; accelerated expansion; parallel universe; duality; antimatter
Online: 17 December 2020 (11:45:26 CET)
The Planck Legacy recent release revealed a closed and positively curved early universe with a confidence level greater than 99%. In this study, the Friedmann–Lemaîtree–Robertson–Walker (FLRW) metric is enhanced to model early universe plasma, incorporating its reference curvature radius upon the emission of the cosmic microwave background (CMB) and the reference scale factor of the energy flux. The universe evolution from early plasma is modelled utilising quantised spacetime worldlines, where they revealed both positive and negative solutions implying that matter and antimatter in the plasma could be separated by electromagnetic fields and evolved in opposite directions as distinct sides of the universe, corroborating the CMB dipole anisotropy. The model indicates a nascent hyperbolic expansion is followed by a first phase of decelerating expansion during the first 10 Gyr, and then, a second phase of accelerating expansion. The model theoretically resolves the tension in Hubble parameter measurements, with a predicted density at the phase transition of 1.16. Further, it predicts a final time-reversal phase of rapid spatial contraction leading to a Big Crunch, signalling a cyclic universe. Simulations of the quantised spacetime continuum flux through its travel along the predicted worldlines demonstrated the fast-orbital speed of stars resulting from an external momentum exerted on galaxies via the spatial curvature through imaginary time dimension. These findings indicate that early universe plasma could be separated and evolved into distinct sides, collectively and geometrically influencing the universe evolution.
ARTICLE | doi:10.20944/preprints202011.0225.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: Stark-Zeeman effect; Rydberg atom; plasma spectroscopy
Online: 6 November 2020 (08:01:41 CET)
A new method of line shape calculations of hydrogen-like atoms in magnetized plasmas is presented. This algorithm makes it possible to solve two fundamental problems in the broadening theory: the analytical description of the radiation transition array between excited atomic states and account of a thermal ion motion effect on the line shapes formation. The solution to the first problem is based on the semiclassical approach to dipole matrix elements calculations and the usage of the specific symmetry properises of the Coulomb field. The second one is considered in terms of the kinetic treatment of the frequency fluctuation model (FFM). As the result one has a universal description of line shapes under the action of the dynamic of ion’s microfield. The final line shape is obtained by the convolution of the ionic line shape with the Voigt electron-Doppler profile. The method is applicable formally for large values of principle quantum numbers. However, it is demonstrated the efficiency of the results even for well known first members of the hydrogen Balmer series Dalpha and Dbeta. The comparison of obtained results with accurate quantum calculations is presented. The new method may be of interest for investigations of spectral line shapes of hydrogen-like ions presented in different kinds of hot ionized environments with the presence of a magnetic field, including SoL and divertor tokamak plasmas.
ARTICLE | doi:10.20944/preprints202009.0719.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Diabetes mellitus, screening, HbA1c, fasting plasma glucose
Online: 29 September 2020 (15:12:26 CEST)
Background: Diabetes is a common non-communicable disease that is responsible for about 9% of all deaths and 25% reduction in life expectancy and nearly half of the diabetic patients are not aware of their disease. In this regard, diabetes screening to identify un-known diabetic patients is of great importance. Aims: The aims of this study were first to evaluate the performance of two commonly used diabetes screening tests that are currently recommended by the Iranian national screening program for diabetes (NSPD). Methods: The validities of the two diabetes screening tests were measured among 1057 participants older than 30 years. The studied screening tests included Capillary fasting blood glucose (CBG) and glycated hemoglobin (HbA1c). The golden standard for measuring the validity of the tests was venous fasting plasma glucose (VPG). Results: According to the results, the sensitivity of CBG and HbA1c tests were 69.01% and 84.5% and the specificity of the tests were 95.7% and 79.3% respectively. Positive and negative predictive values were 53.84% and 97.72% for CBG and 22.72% and 98.61% for HbA1c respectively. The recommended cut-points for CBG and HbA1c were 116.5 mg/dl and 7.15% respectively. Using these values as the new cut-points, sensitivity and specificity of CBG and HbA1c changed to 80.30% and 89.10%, and 77.50% and 94.20% respectively. Conclusions: Compared to several other countries, the performance of NSPD is relatively higher in Iran. ROC analysis suggested new cut-points for significantly better performance of NSPD.
REVIEW | doi:10.20944/preprints202007.0090.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: COVID-19; Immunotherapy; Immunomodulator; Antibody; Plasma; Immunoglobulins
Online: 5 July 2020 (17:01:31 CEST)
Since the outbreak of SARS CoV-2 infection (Covid-19), healthcare professionals worldwide have been trying to find disease management and control alternatives to encourage immunotherapies. Immunotherapy is an efficient therapeutic option used against comparable viral contaminations such as MERS-CoV and SARS-CoV. The aim of the current study is to assess the existing knowledge associated with SARS-CoV-2 immunotherapy. Information available in published articles and their quality highlights the importance of following strict scientific rules for clinical outcomes. Thus, these studies have shown enough data to confirm that immunomodulation is the main topic investigated in research about Covid-19 therapy. Therefore, it is possible saying that immunotherapy is certainly the appropriate option against this virus.
REVIEW | doi:10.20944/preprints202006.0263.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: biomarker; blood/plasma; cancer; ctDNA; liquid biopsy
Online: 21 June 2020 (11:22:36 CEST)
Circulating tumor DNA (ctDNA) in fluids has gained attention because ctDNA seems to identify tumor-specific abnormalities, which could be used for diagnosis, follow-up of treatment, and prognosis: the so-called liquid biopsy. Liquid biopsy is a minimally invasive approach and presents the sum of ctDNA from primary and secondary tumor sites. It has been possible not only to quantify the amount of ctDNA but also to identify (epi)genetic changes. Specific mutations in genes have been identified in the plasma of patients with several types of cancer, which highlights ctDNA as a possible cancer biomarker. However, achieving detectable concentrations of ctDNA in body fluids is not an easy task. ctDNA fragments present a short half-life, and there are no cut-off values to discriminate high and low ctDNA concentrations. Here, we discuss the use of ctDNA as a cancer biomarker, the main methodologies, the inherent difficulties, and the clinical predictive value of ctDNA.
ARTICLE | doi:10.20944/preprints202005.0406.v1
Subject: Medicine And Pharmacology, Dietetics And Nutrition Keywords: Drospirenone 4mg; breastfeeding; plasma concentration; milk concentration
Online: 24 May 2020 (20:26:11 CEST)
Objective: The primary objective of this trial was to assess the transfer of drospirenone to breast milk after daily administration of an oral test preparation containing 4 mg of drospirenone at the steady state. The secondary objective of the trial was to assess the safety of the preparation based on safety clinical and laboratory measurements (at the beginning and at the end of the trial) and reporting of adverse events and/or adverse drug reactions. Patients and Methods: This was an open label, non-comparative single center study. Drospirenone 4mg per day was the first postpartum contraceptive for the study participants who were no longer breastfeeding yet were still lactating. It was administered for 7 (seven) days to achieve steady-state concentration. All participants were volunteers who planned to use oral contraceptives as their family planning method in the future. Results: A total number of 12 volunteers completed the trial according to the protocol and the samples of all the 12 study completers were analyzed. The average concentration-time curve of drospirenone in plasma 24 h after the administration of the last dose (AUC(0-24h)) was 635.33 ng*h/mL and 120 h after the single repeat dose administration (AUC(0-120h) was 1180.57 ng*h/mL, respectively. The average Cmax was 48.64 ng/mL. The average concentration-time curve of drospirenone in milk 24 h after the administration of the last dose (AUC(0-24h)) was 134.35 ng*h/mL and 120 h after the single repeat dose administration (AUC(0-120h) was 227.17 ng*h/mL respectively. The average Cmax was 10.34 ng/mL. Conclusion: On average 18.13% of plasma drospirenone made it to breast milk and the highest concentration of drospirenone in breast milk was 17.55% of that in plasma. The total quantity of drospirenone passing to breast milk is on average 4478 ng during a 24 h period representing 0.11% of the maternal daily dose. Thus, at the recommended doses, no effects on breastfed newborns/infants are anticipated with drospirenone 4 mg.
ARTICLE | doi:10.20944/preprints201812.0326.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: Ti-6Al-4V alloy; plasma nitriding; fatigue
Online: 28 December 2018 (03:57:18 CET)
The Ti-6Al-4V alloy is widely used in the manufacture of components that should have low density, high corrosion resistance, and fatigue strength. The fatigue strength can be improved by surface modification. The aim of this study was to determine the influence of plasma nitriding on the fatigue behavior of Ti-6Al-4V alloy with a lamellar microstructure (Widmanstätten type). Nitriding was executed at 720 °C for 4 hours in an atmosphere with N2, Ar and H2. Samples microstructure characterization was carried out by X-ray diffraction analysis, optical microscopy and scanning electron microscopy. The average roughness of the specimens was determined, and fatigue tests were executed in a bending-rotating machine with reverse tension cycles (R= -1). X-ray diffraction analysis revealed the matrix phases α and β, and the phases Ɛ-Ti2N and δ-TiN in the nitrided alloy. A nitrogen diffusion layer was formed between the substrate and the titanium nitrides. Plasma nitriding resulted in an increase in low cycle fatigue strength, whereas at high cycles, both conditions exhibit similar behavior. The fracture surface of the fatigue tested specimens clearly revealed the lamellar microstructure. The fracture mechanism appears to be due to cracking at the interface of α and β phases of the lamellar microstructure.
ARTICLE | doi:10.20944/preprints201711.0099.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: renal function; iohexol plasma clearance; swine model
Online: 16 November 2017 (03:11:30 CET)
There is no simple method to measure glomerular filtration rate (GFR) in swine, an established model to study renal disease. We developed a protocol to measure GFR in conscious swine with the plasma clearance of iohexol. We used two groups: testing and validation, of 8 animals each. Ten milliliters of iohexol (6.47 g) were injected by the marginal auricular vein and blood samples (3 ml) were collected from the orbital sinus at different points after injection. GFR was determined considering two models: two-compartments (CL2: all samples) and one-compartment (CL1: the last six samples). In the testing group, CL1 overestimated CL2 by ~30%: CL2=245±93 and CL1=308±123 ml/mn. This error was corrected by a first order polynomial quadratic equation to CL1, which was considered the simplified method: SM=-47.909+(1.176xCL1)–(0.00063968xCL12). SM showed narrow limits of agreement with CL2, and a concordance correlation of 0.97 and a total deviation index of 14.73%. Similar results were obtained for the validation group. This protocol is reliable, reproducible, can be performed in conscious animals, uses a single dose of the marker, and requires a reduced number of samples avoiding urine collection. Finally, it portends a significant improvement in animal-welfare conditions and handling necessities in experimental trials.
ARTICLE | doi:10.20944/preprints202111.0273.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: General Relativity; Improved Schwarzschild Black hole; Plasma medium; Gauss-Bonnet theorem; Non plasma medium; Hawking radiation; Greybody Factor.
Online: 15 November 2021 (19:36:28 CET)
We explore the deflection angle in the framework of improved Schwarzschild Black hole utilizing the most advance geometrical path adopted by Gibbon-Werner. To investigate deflection angle of the photon ray by weak gravitational lensing for this black hole, we derive the optical curvature and perform the application of Gauss-Bonnet theorem on the optical metric. Moreover, we study the impacts of the plasma medium in context of the weak gravitational lensing in relate to this black hole. Further, we also study the graphical analysis of the deflection angle in both the plasma and non-plasma mediums. Also, we find the rigorous bound base upon the greybody factor for improved Schwarzschild black hole. A while later, we contrast our conclusions about deflection angle with the deflection angles of Schwarzschild black hole within plasma and non-plasma mediums.
ARTICLE | doi:10.20944/preprints202012.0025.v1
Subject: Physical Sciences, Acoustics Keywords: plasma-liquid interactions; water electrospray; aerosol microdroplet; bulk water, plasma-activated water; Henry’s law solubility; ozone; hydrogen peroxide
Online: 1 December 2020 (13:16:22 CET)
Production and transport of reactive species through plasma-liquid interactions plays a significant role in multiple applications in biomedicine, environment, and agriculture. We experimentally investigated the transport mechanisms of hydrogen peroxide H2O2 and ozone O3, as the typical plasma species, into water. We measured the solvation of gaseous H2O2 and O3 in airflow into water bulk vs. electrosprayed microdroplets while changing the gas and water flow rates, applied voltage that determines the gas-liquid interface area, and treatment time. The solvation rate of H2O2 and O3 increased with the treatment time and the gas-liquid interface area. The total surface area of the electrosprayed microdroplets was larger than that of the bulk, but their lifetime was much shorter. We estimated that only microdroplets with diameters below ~ 40 µm could achieve the saturation by O3 during their lifetime, while the saturation by H2O2 was impossible due to its depletion from air. Besides the short-lived flying microdroplets, the longer-lived bottom microdroplets substantially contributed to H2O2 and O3 solvation in water electrospray. This study contributes to a better understanding of the gaseous H2O2 and O3 transport into water as a function of different parameters and will lead to design optimization of the plasma-liquid interaction systems.
ARTICLE | doi:10.20944/preprints202007.0321.v1
Subject: Computer Science And Mathematics, Applied Mathematics Keywords: Collisionless plasma dynamics; Gaseous plasma; Vlasov equation; Maxwell equations; Entropy; Extended Gibbs formula; The Earth's plasmasphere; the magnetosphere.
Online: 15 July 2020 (08:47:59 CEST)
In the upper charged layers of the atmosphere, the plasma is very rarefied. The collisions between its molecules are almost non-existent, and the driving forces behind them are the Lorentz forces resulting from the electric and magnetic fields. For this reason, we are interested in studying the behavior of non-collision plasmas because of its essential applications, such as the movement of satellites in the charged atmosphere. In this paper, the flow problem of collisionless gaseous plasma is examined. For that propose, we solve the unsteady Vlasov-Maxwell system of non-linear partial differential equations analytically. Methods of moments and traveling wave parameters are used to acquire an exact solution. Specific macroscopic properties of collisionless gaseous plasma are calculated along with electrical and magnetic fields. Further, thermodynamic estimation, such as entropy and entropy production, is presented. Those calculations allow us to measure the consistency with the laws of non-equilibrium thermodynamics. Relations between internal energy modification participations are predicted using Gibbs' equation for collisionless plasma. The modification effect of internal energies due to electro-magnetic fields is found to be small compared with the internal energy change due to the effect of entropy. That is because these fields are self-induced by plasma particles due to the sudden movement of the rigid plane plate. The results are accomplished according to the typical argon gaseous plasma model. Three-dimensional diagrams showing the measured variables are drawn to investigate and discuss their behavior. The problem has many commercial applications for the movement of objects in the charged atmosphere.
ARTICLE | doi:10.20944/preprints202112.0076.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: oxygen plasma 2; active oxygen species 3; plasma irradiation on seed and leaf 4; growth enhancement 5; gene expression
Online: 6 December 2021 (13:28:01 CET)
Gene expression variations of plant leaf are investigated by irradiating seed and leaf with oxygen or air plasmas. Enhancement of leaf growth is induced by oxygen plasma irradiation on seeds, which is supported by increased gene expression for protein synthesis, oxidative-reduction reactions and decreased gene expression concerning DNA methylation and histone modification. Suppression of leaf growth is observed by the oxygen plasma, which would be owing to increased gene expression concerning heat shock protein and redox reaction, and decreased expression of photosynthesis and glycoprotein. Also, gene expression variation due to air plasma irradiation is almost same as that of oxygen plasma. Active oxygen species are major factors in both oxygen and air plasmas for the variation of gene expressions in plant.
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: plasma diagnostics; molecular spectra; diatomic molecules; plasma spectroscopy; laser spectroscopy; laser-induced breakdown spectroscopy; optical emission spectroscopy; hypersonic expansion
Online: 15 January 2020 (07:12:25 CET)
This article reports new measurements of laser-induced plasma hypersonic expansion measurements of diatomic molecular cyanide (CN). Focused, high-peak power 1064-nm Q-switched radiation of the order of 1 TW/cm2 generates optical breakdown plasma in a cell containing a 1:1 molar gas mixture of N2 and CO2 at a fixed pressure of 1.1 × 105 Pascal and in a 100 ml/min flow of the mixture. Line-of-sight (LOS) analysis of recorded molecular spectra indicate the outgoing shockwave at expansion speeds well in excess of Mach number 5. Spectra of atomic carbon confirm an increased electron density near the shock wave, and equally, molecular CN spectra reveal higher excitation temperature near the shockwave. The results are consistent with corresponding high-speed shadow graphs obtained by visualization with an effective shutter speed of five n anosecond. In addition, LOS analysis and application of integral inversion techniques allow inferences about the spatio-temporal distribution of the plasma.
ARTICLE | doi:10.20944/preprints202310.0878.v1
Subject: Biology And Life Sciences, Other Keywords: AKT; cold atmospheric plasma; ERK; miRNA; oral carcinoma
Online: 13 October 2023 (10:04:03 CEST)
Despite recent advancements, therapies remain ineffective against advanced oral squamous cell carcinoma (OSCC), resulting in unsatisfactory therapeutic outcomes. Cold atmospheric plasma (CAP) offers a promising approach in the treatment of malignant neoplasms. Yet, the exact mechanisms driving CAP-induced cancer cell death are not fully understood. This study revealed a significant reduction in the viability of OSCC cell lines, inactivation of AKT and ERK, and the downregulation of the miR-21, miR-31, miR-134, miR-146a and miR-211 expression followed the CAP treatment. Pretreatment with ZVAD, 3-MA, and Fer-1 synergistically reduced CAP-induced cell death, indicating a combined induction of variable death pathways by CAP. Activation of AKT and ERK, alongside combined treatments using death inhibitors and miRNA mimics, counteracted the cell mortality associated with CAP. CAP-induced downregulation of miR-21, miR-31, miR-187 and miR-211 expression was rescued by AKT and ERK activation. Additionally, CAP treatments notably inhibited the growth of SAS cell xenografts on nude mice. The reduced expression of oncogenic miRNAs in vivo aligned with in vitro findings. In conclusion, our study indicates that CAP jet treatment diminishes OSCC cell viability by abrogating survival signals and oncogenic miRNA expression.
ARTICLE | doi:10.20944/preprints202309.1065.v1
Subject: Medicine And Pharmacology, Dermatology Keywords: psoriasis; plasma cytokines; TNFα inhibitors; etanercept; infliximab; adalimumab
Online: 18 September 2023 (02:32:17 CEST)
An analysis of the relationship between plasma cytokines and the effectiveness of treatment with TNFαinhibitors was performed in 81 patients with moderate-to-severe psoriasis. Treatment efficacy was assessed by PASI score, and patients were classified into a positive effect (PASI≥75) and no effect group (PASI≤50). A positive effect was reached in 11 (41%) patients for etanercept, 14 (52%) for adalimumab, and 26 (96%) for infliximab. Data analysis did not show differences in baseline TNFα levels and subsequent treatment effectiveness. The CART algorithm showed that at the baseline level of VEGF ≥ 32 pg/ml and IL17F < 26 pg/ml, there was an 83% probability of a positive effect. Random forest analysis showed the importance of VEGF, ICAM1, sCD40L, IL17F and IL31 baseline levels in the prediction of treatment effectiveness. Significant differences between the groups before/after the treatment were found only for TNFα: the median values were more than 50 times higher in no effect compared with positive effect group. There were differences before/after therapy in the levels of IL20, ICAM1, IL22, IL23 in the no effect group. The treatment affected the cytokine profile in most cases regardless of the effectiveness of therapy.
BRIEF REPORT | doi:10.20944/preprints202306.1358.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: Liquid biopsy; PD-L1; plasma cfRNA; immunotherapy; NSCLC
Online: 19 June 2023 (12:57:52 CEST)
Tissue programmed death ligand-1 (PD-L1) protein is the recognized predictive immune biomarker of immune checkpoint inhibitor (ICI) treatment benefit in metastatic non-small cell lung cancer (NSCLC). However, tissue PD-L1 protein testing can be limited by tumor heterogeneity and fraught with tissue acquisition difficulties. A plasma PD-L1 assay potentially overcomes these tissue limitations. Patients with metastatic NSCLC treated with first-line ICI-based treatment and available results of plasma cfRNA PD-L1 by real-time polymerase chain reaction (RT-PCR) and tissue PD-L1 protein PD-L1 with the Dako 22C3 monoclonal antibody were retrospectively assessed for median and landmark 3-year overall survival (OS). OS was identical whether positive plasma cfRNA PD-L1 expression or positive tissue PD-L1 protein expression (median OS 15 months; 3-year landmark OS 30%; hazard ratio (HR) 0.97; 95% CI, 0.44-2.10). Positive plasma cfRNA PD-L1 patients also demonstrated a numerically longer median and higher 3-year OS compared to patients lacking PD-L1 expression (median 15 months versus 8 months; 3-year landmark OS 30% versus 15%; HR 0.56; 95% CI, 0.27-1.17). Plasma cfRNA PD-L1 expression by RT-PCR was similarly predictive of ICI-based treatment benefit as tissue PD-L1 protein expression.
ARTICLE | doi:10.20944/preprints202306.0566.v1
Subject: Engineering, Metallurgy And Metallurgical Engineering Keywords: YSZ suspension; Water; Ethanol; Plasma Spraying; Columnar coating
Online: 8 June 2023 (02:10:01 CEST)
In this paper, applicability of the modified water-based yttria stabilized zirconia (YSZ) suspensions, including different dispersants, to produce plasma sprayed coatings with “columnar microstructure” is investigated. The effects of processing parameters like suspension liquid phase ethanol content, change of substrate roughness, and spray distance on the resulting coatings morphologies are investigated. The results showed that increasing ethanol concentration, substrate surface roughness, and the spray distance promote formation of coatings with columnar structure. Moreover, application of modified water-based suspensions including α-Terpineol dispersant has led to deposition of columnar coatings with comparable morphologies of coatings deposited from ethanol-based suspensions.
ARTICLE | doi:10.20944/preprints202305.1015.v1
Subject: Chemistry And Materials Science, Ceramics And Composites Keywords: tungsten carbide; silicon carbide; spark plasma sintering; nanopowder
Online: 15 May 2023 (10:06:48 CEST)
This paper investigates the density, phase composition, microstructure and mechanical properties (microhardness, fracture toughness) of binderless WC + SiC ceramics obtained by conventional pressureless sintering (CPS) and Spark Plasma Sintering (SPS). α-WC nanopowders obtained by DC arc plasma chemical synthesis and β-SiC powders have been used as raw materials. The content of SiC particles was 1, 3, 5% wt. Excess graphite (0.3, 0.5% wt.) was added to α-WC nanopowders to decrease the volume fraction of W2C particles that negatively affect the mechanical properties of ceramics. WC + 1% wt. SiC + 0.3% wt. C ceramics are shown to have a homogeneous fine-grained microstructure, high relative density, increased microhardness and Palmquist fracture toughness. The CPS and SPS activation energies of WC + SiC nanopowders at an intensive shrinkage stage are determined using the Young-Cutler model. The effect of carbon and SiC particles on the CPS and SPS activation energies of tungsten carbide nanopowders has been analyzed. The CPS activation energies of WC, WC + C and WC + SiC + C nanopowders are shown to be closer to the carbon diffusion activation energy along α-WC grain boundaries. The SPS activation energies of WC and WC + SiC nanopowders turn out to be lower than the carbon grain boundary diffusion activation energy of α-WC.
ARTICLE | doi:10.20944/preprints202304.0451.v1
Subject: Public Health And Healthcare, Public Health And Health Services Keywords: VEGF; Aptasensor; Streptavidin magnetic bead; Plasma; Hybridization probe
Online: 17 April 2023 (10:43:37 CEST)
In this study, a simple, easy and convenient fluorescent sensing system for detection of vascular endothelial growth factor (VEGF) based on VEGF aptamers, aptamer-complementary fluorescence-labeled probe and streptavidin magnetic beads was developed in only one single tube. The VEGF is the most important biomarker in cancer angiogenesis, and is investigated that serum VEGF level was various according to the different type and course of cancers. Hence, efficient quantification of VEGF is able to improve the accuracy of cancer diagnosis and precision of disease surveillance. In this research, the VEGF aptamer was designed to be able to bind with the VEGF by forming G-quadruplex secondary structures, and then the magnetic beads would capture the none-binding aptamers due to none steric interference, and finally, the fluorescence-labeled probes were hybridized with the aptamers captured by the magnetic beads. Therefore, the fluorescent intensity in the supernatant would specifically reflect the present of VEGF. After an overall optimization, the optimal conditions for detection of VEGF were as followed, KCl, 50 μM; pH 7.0; aptamer, 0.1 μM and magnetic beads, 10 μL (4 μg/μL). The VEGF could be well quantified within a range of 0.2-2.0 ng/ml in plasma, and the calibration curve possessed a good linearity (y = 1.0391x + 0.5471, r = 0.998). The detection limit (LOD) was calculated to be 0.0445 ng/mL according to the formula (LOD = 3.3×σ/S). The specificity of this method was also investigated under the appearance of many other serum proteins, and the data showed the good specificity in this aptasensor-based magnetic sensing system. This strategy provided a simple, sensitive and selective biosensing platform for detection of serum VEGF. Finally, it was expected that this detection technique can be promoted to more clinical applications.
ARTICLE | doi:10.20944/preprints202209.0449.v1
Subject: Engineering, Energy And Fuel Technology Keywords: pulsed power plasma discharge; electromagnetic; COMSOL; numerical simulation
Online: 29 September 2022 (03:32:36 CEST)
The scope of this work was part of our previous research on Pulsed Power Plasma Stimulation Technique. Electromagnetic fields generated during a pulsed power plasma discharge were simulated using a finite element method in the COMSOL RF module. The field distributions were calculated during and after the pulse. The current paper takes advantage of prior work measuring and modeling the current distribution in the plasma arc. Agreement with laboratory experimental measurements provides support for extension of the model to reservoir scale. The validated model was used to quantify the signal attenuation level in different medium environment.
ARTICLE | doi:10.20944/preprints202110.0404.v1
Subject: Medicine And Pharmacology, Hematology Keywords: pathogen reduction; blood safety; platelet transfusion; INTERCEPT; plasma
Online: 27 October 2021 (12:27:33 CEST)
(1) Background: We reviewed the logistics of the implementation of pathogen inactivation (PI) using the INTERCEPT Blood System™ for platelets and the experience with routine use and clinical outcomes in the patient population at the Sírio-Libanês Hospital of São Paulo, Brazil. (2) Methods: Platelet concentrate (PC), including pathogen reduced (PR-PC) production, inventory management, discard rates, blood utilization, and clinical outcomes were analyzed over the 40 months before and after PI implementation. Age distribution and wastage rates were compared over the 10 months before and after approval for PR-PC to be stored for up to 7 days. (3) Results: A 100% PR-PC inventory was achieved by increasing double apheresis collections and production of double doses using pools of two single apheresis units. Discard rates decreased from 6% to 3% after PI implementation and further decreased to 1.2% after 7-day storage extension for PR-PCs. The blood utilization remained stable, with no increase in component utilization. A significant decrease in adverse transfusion events was observed after the PI implementation. (4) Conclusion: Our experience demonstrates the feasibility for Brazilian blood centers to achieve a 100% PR-PC inventory. All patients at our hospital received PR-PC and showed no increase in blood component utilization and decreased rates of adverse transfusion reactions.
ARTICLE | doi:10.20944/preprints201905.0371.v1
Subject: Physical Sciences, Astronomy And Astrophysics Keywords: non-extensive entropic principle; plasma turbulence; quasi equilibrium
Online: 31 May 2019 (06:12:02 CEST)
The Boltzmann-Gibbs (BG) entropy has been used in a wide variety of problems for more than a century. It is well known that BG entropy is extensive, but for certain systems such as those dictated by long-range interactions, the entropy must be non-extensive. Tsallis entropy possesses non-extensive characteristics, which is parametrized by a variable q (q = 1 being the classic BG limit), but unless q is determined from microscopic dynamics, the model remains but a phenomenological tool. To this date very few examples have emerged in which q can be computed from first principles. This paper shows that the space plasma environment, which is governed by long-range collective electromagnetic interaction, represents a perfect example for which the q parameter can be computed from micro-physics. By taking the electron velocity distribution function measured in the heliospheric environment into account, and considering them to be in quasi equilibrium state with electrostatic turbulence known as the quasi-thermal noise, it is shown that the value corresponding to q = 9/13 = 0.6923 may be deduced. This prediction is verified against observation made by spacecraft, and it is shown to be in excellent agreement.
ARTICLE | doi:10.20944/preprints201905.0241.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: gold; surface of electrodes; ozone; plasma; raids layer
Online: 20 May 2019 (10:31:34 CEST)
During the long-term operation of the plasma reactor, decreases in the plasma concentration were noticed despite the constant maintenance of all parameters. One of the factors is the decrease of the nitrogen content on the surface of the electrode, in order to eliminate it, the supply voltage has been increased to 11 kV. The next decisive factor in the decrease of plasma concentration is the oxidation of the electrode surface, therefore two electrodes were used: first one with solid gold and the other one copper covered with galvanized gold with a thickness of 10 μm. During the experiment, a large decrease in plasma concentration was observed when the electrode coated by gold was used. High-energy electrons have knocked out the gold atoms from the electrode, as a result of which the gold evaporated and the raids layers formed. After a month of working of the electrodes, metallographic researches were carried out, the results of which are described in this publication.
COMMUNICATION | doi:10.20944/preprints201905.0163.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: plasma spray; in-flight particles; molten status; YSZ
Online: 13 May 2019 (14:18:40 CEST)
In order to achieve better knowledge of the thermal barrier coatings (TBCs) by supersonic atmospheric plasma spraying (SAPS) process, an experimental study was carried out to elaborate physicochemical properties of particles in-flight during the SAPS process. One type of commercially available agglomerated and sintered yttria-stabilized-zirconia (YSZ) powders were injected into the SAPS plasma jet and collected by shock chilling method. The YSZ particles in-flight physicochemical properties of the melting state, morphology, microstructure, particle size distribution, element composition changes and phase transformation during the SAPS process have been systematically analyzed. The melting state, morphology and microstructure of the collected particles were determined by scanning electron microscopy (SEM). The particle size distribution was measured by a laser particle size analyzer (LPSA). Element compositions were quantitatively analysed by an electron probe X-ray microanalyzer (EPMA). Additionally, the X-ray diffraction (XRD) method was used to analyse the phase transformation. The results showed that the original YSZ powders injected into the SAPS plasma jet were quickly heated and melted from the outer layer companied with breakup and collision-coalescence. The outer layer of the collected particles containing roughly hexagonal shaped grains exhibited a surface texture with high sphericity and the inside was dense with hollow structure. The median particle size was decreased from 45.65 μm to 42.04 μm. Besides, phase transformation took place and the content of zirconium (Zr) and yttrium (Y) element was decreased with the evaporation of ZrO2 and Y2O3.
ARTICLE | doi:10.20944/preprints201811.0482.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: polycaprolactone; oxygen plasma; Wharton’s Jelly mesenchymal stem cells
Online: 20 November 2018 (05:26:00 CET)
Cell-based therapies and tissue engineering applications require biocompatible substrates that support and regulate the growth, survival, and differentiation of specific cell types. Extensive research efforts in regenerative medicine are devoted to the development of tunable biomaterials which support various cell types including stem cells. In this research, the non-cytotoxic biopolymer polycaprolactone (PCL) was fabricated into 2D and 3D scaffolds with or without the low-pressure oxygen plasma treatment to enhance hydrophilicity. Cellular responses and biocompatibility were evaluated using a human Wharton’s jelly mesenchymal stem cell line (BCP-K1). The 2D PCL scaffolds enhanced initial cell attachment compared to the 3Ds indicated by a higher expression of focal adhesion kinase (FAK). Whilst, the 3D scaffolds promoted cell proliferation and migration as evidenced by higher cyclin A expression and filopodial protrusion, respectively. The 3D scaffolds potentially protected the cell entering to apoptosis/necrosis program and induced cell differentiation, evaluated by gene expression. Both 2D and 3D PCL appeared to have stronger effects on cell behavior than a control substrate (polystyrene). In summarize, the different configuration and surface properties of PCL scaffolds provide various options for modulation of stem cell behaviors, including attachment, proliferation, survival, and differentiation, when combined with specific growth factors and culture conditions.
ARTICLE | doi:10.20944/preprints201805.0446.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: plasma-TIG; coupled arc; arc profile; pressure distribution
Online: 30 May 2018 (09:39:07 CEST)
In this article, a novel hybrid welding process called plasma-TIG coupled arc welding was proposed to improve the efficiency and quality of welding by utilizing the full advantage of plasma and TIG welding processes. The two arcs of plasma and TIG were pulled into each other into one coupled arc under the effect of Lorentz force and plasma flow force during welding experiments. The arc behavior of coupled arc was studied by means of it’s arc profile, arc pressure and arc force conditions. The coupled arc pressure distribution measurements were performed. The effects of welding conditions on coupled arc pressure were evaluated and the maximum coupled arc pressure was improved compared with single-plasma arc and single-TIG arc. It was found that the maximum arc pressure was mainly determined by plasma arc current and plasma gas flow. According to the results, the proposed coupled arc welding process have both advantages of plasma arc and TIG method, and it has a broad application prospect.
ARTICLE | doi:10.20944/preprints201704.0080.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: metabolomics; LC-MS; GC-MS; plasma; brain tissue
Online: 14 April 2017 (04:41:05 CEST)
Metabolomic analysis of biological fluids and tissues has become an increasingly routine tool in the biological toolbox. However, challenges remain to be overcome, including developing strategies to maximise coverage of the metabolome without requiring large sample volumes. Here we describe a multimodal strategy that combines data using both LC-MS and GC-MS from a unique vial with a sample of plasma (20µl) or a sample of brain tissue (3mg). Using a split phase extraction the non-aqueous phase was analyzed by reversed phase (RP) LC-MS, whilst the aqueous phase was analyzed using hydrophilic liquid interaction chromatography (HILIC)LC-MS, with both phases also analysed using GC-MS after derivatization of the extract. Analytical performance was assessed in 7 rat cerebellum samples and a pilot study of 40 plasma samples (20 vs. 20: AD vs. healthy controls). The method, which uses four hours of instrument time, measured 20,707 metabolite features in brain samples and 17,266 in plasma samples, from those 44.1% features displayed CV’s below 15% and 75.2% below 30%. The method has potential to resolve subtle biological differences and to correlate metabolite composition directly to clinical outcomes including MMSE, age and ADCS-ADL. This method can acquire in the order of 20K metabolic features when low volumes are available.
ARTICLE | doi:10.20944/preprints202011.0652.v1
Subject: Physical Sciences, Acoustics Keywords: laser–plasma interactions; plasma dynamics and flow; hypersonic flows; optical emission spectroscopy; hydrogen; cyanide; Abel inversion; astrophysics; white dwarf stars
Online: 25 November 2020 (16:23:06 CET)
This work communicates the connection of measured shadowgraphs from optically induced air breakdown with emission spectroscopy in selected gas mixtures. Laser-induced optical breakdown is generated using 850 mJ and 170 mJ, 6-ns pulses at a wavelength of 1064 nm, the shadowgraphs are recorded using time-delayed 5-ns pulses at a wavelength of 532 nm and a digital camera, and emission spectra are recorded for typically a dozen of discrete time-delays from optical breakdown by employing an intensified charge-coupled device. The symmetry of the breakdown event can be viewed as close-to spherical symmetry for time-delays of several 100 ns. Spectroscopic analysis explores well-above hypersonic expansion dynamics using primarily the diatomic molecule cyanide and atomic hydrogen emission spectroscopy. Analysis of the air breakdown and selected gas breakdown events permits the use of Abel inversion for inference of the expanding species distribution. Typically, species are prevalent at higher density near the hypersonically expanding shockwave, measured by tracing cyanide and a specific carbon atomic line. Overall, recorded air breakdown shadowgraphs are indicative of laser-plasma expansion in selected gas mixtures, and optical spectroscopy delivers analytical insight into plasma expansion phenomena.
ARTICLE | doi:10.20944/preprints201803.0037.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: Stark broadening; van der Waals broadening; line shapes; helium plasma; corona discharge; plasma diagnostics; code comparison; neutral broadening; pressure broadening
Online: 7 March 2018 (13:36:47 CET)
Passive plasma spectroscopy is a well-established non-intrusive diagnostic technique. Depending on the emitter and its environment which determine the dominant interactions and effects governing emission line shapes, passive spectroscopy allows the determination of electron densities, emitter and perturber temperatures as well as other quantities like abundances. However, using spectroscopy needs appropriate line shape codes retaining all the physical effects governing the emission line profiles. This requires for line shape code developers to continuously correct or improve them to increase their accuracy when applied for diagnostics. This is exactly the aim expected from code-code and code-data comparisons. In this context, the He I 492 nm emitted in a helium corona discharge at room temperature represents an ideal case since its profile results from several broadening mechanisms: Stark, Doppler, resonance and van der Waals. The importance of each broadening mechanism depends on the plasma parameters. Here the profiles of the He I 492 nm in a helium plasma computed by various codes are compared for a selected set of plasma parameters. In addition, preliminary results related to plasma parameter determination using experimental spectra from a helium corona discharge at low pressure 1- 2 bars, are presented.
ARTICLE | doi:10.20944/preprints201803.0040.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: stark broadening; van der waals broadening; line shapes; helium plasma; corona discharge; plasma diagnostics; code comparison; neutral broadening; pressure broadening
Online: 6 March 2018 (03:51:17 CET)
Many spectroscopic diagnostics are routinely used as a technique to infer the plasma parameters from line emission spectra but their accuracy depends on the numerical model or code used for the fitting process. However, the validation of a line shape code requires some steps : comparison of the line shape code with other similar codes for some academic (simple) cases and then more complex ones, comparison of the fitting parameters obtained from the best fit of the experimental spectra with those obtained with other diagnostic techniques and/or comparison of the fitting parameters obtained by different codes to fit the same experimental data. Here we compare the profiles of the hydrogen Balmer β line in a helium plasma computed by six codes for a selected set of plasma parameters and we report on the plasma parameters inferred by each of them from the fitting to a number of experimental spectra measured in a helium corona discharge where the pressure was in the range 1- 5 bar.
ARTICLE | doi:10.20944/preprints202207.0390.v1
Subject: Physical Sciences, Astronomy And Astrophysics Keywords: general relativity; gravitational lensing; wormhole-like static aether solution; Gauss-Bonnet theorem; plasma and non-plasma mediums; dark matter; modified gravity
Online: 26 July 2022 (06:12:06 CEST)
In this paper, we study the deflection angle for wormhole-like static aether solution by using Gibbons and Werner technique in non-plasma, plasma and dark matter mediums. For this purpose, we use optical spacetime geometry to calculate the Gaussian optical curvature, then implement the Gauss-Bonnet theorem in weak field limits. Moreover, we compute the deflection angle by using a technique known as Keeton and Petters technique. Furthermore, we analyze the graphical behaviour of the bending angle ψ with respect to the impact parameter b, mass m as integration constant and parameter q in non-plasma and plasma mediums. We examine that deflection angle is exponentially increasing as direct with charge. Also, we observe that for small values of b, ψ increases and for large values of b the angle deceases. We also considered an analysis to the shadow cast of the wormhole relative to an observer at various locations. Comparing it the the Schwarzschild shadow, shadow cast is possible for wormhole as r<2m. At r>2m, the Schwarzschild is larger. As r → ∞, we have seen that the behavior of the shadow, as well as the weak deflection angle, approaches that of the Schwarzschild black hole. Overall, the effect of plasma tends to decrease the value of the observables due to the wormhole geometry.
ARTICLE | doi:10.20944/preprints201804.0069.v1
Subject: Engineering, Energy And Fuel Technology Keywords: non-thermal plasma; wood gasification; charcoal gasification; water steam gasification; plasma stability; optical temperature measurement; carbon conversion; reaction kinetics; Arrhenius diagram
Online: 5 April 2018 (11:13:38 CEST)
Compared to conventional allothermal gasification of solid fuels (e.g. biomass, charcoal, lignite etc.), plasma-assisted gasification offers an efficient method to apply energy into the gasification process to increase the flexibility of operation conditions and to increase the reaction kinetics. In particular, non-thermal plasmas (NTP) are promising, in which thermal equilibrium is not reached and electrons have substantially higher mean energy than gas molecules. Thus it is generally assumed that in NTP the supplied energy is utilized more efficiently for generating free radicals initiating gasification reactions than thermal plasma processes. In order to investigate this hypothesis, we compared purely thermal to non-thermal plasma assisted gasification of biomass in steam in a drop tube reactor at atmospheric pressure. The NTP was provided by means of gliding arcs between two electrodes aligned in the inlet steam flow. Electric power of about 1 kW was supplied using a high voltage generator operating at frequencies between 70 and 150 kHz and voltage amplitudes up to 10 kV. A laser-assisted optical method (Raman spectroscopy) was applied for measuring the gas temperature both in the conventionally heated steam and flow-down of the visible plasma filaments of the gliding arcs. Reaction yields and rates were evaluated using these measured gas temperatures. The first experimental results have shown that the non-thermal plasma not only promotes the carbon conversion of the fuel particles, but also accelerates the reaction kinetics. The carbon conversion is increased by nearly 10% using wood powder as the fuel. With charcoal powder more than 3% are converted into syngas.
REVIEW | doi:10.20944/preprints202311.1329.v1
Subject: Public Health And Healthcare, Other Keywords: COVID-19; SARS-CoV-2; convalescent plasma; hyperimmune immunoglobulins
Online: 22 November 2023 (02:29:07 CET)
Since late 2019, COVID-19, a severe acute respiratory syndrome pandemic, was caused by the new SARS-CoV-2 virus belonging to the Coronaviridae family, . Several antiviral therapies, mostly derived from previous epidemics, were initially repurposed to fight this not rarely life-threatening respiratory illness. Among them, however, the only specific antibody-based therapy available against SARS-CoV-2 infection during the first year of the pandemic was represented by COVID-19 convalescent plasma (CCP). CCP, collected from recovered individuals, contains high levels of polyclonal antibodies of different subclasses able to neutralize SARS-CoV-2 infection. Tens of randomized controlled trials have been conducted during the last three years of the pandemic to evaluate the safety and the clinical efficacy of CCP in both hospitalized and ambulatory COVID-19 patients, whose main results will be summarized in this narrative review. In addition, we will present the current knowledge on the development of anti-SARS-CoV-2 hyperimmune polyclonal immunoglobulins.
ARTICLE | doi:10.20944/preprints202311.0068.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: Primary hyperparathyroidism; Plasma atherogenic index; Atherosclerosis; Coronary flow reserve
Online: 1 November 2023 (13:16:23 CET)
Introduction: The coronary flow reserve (CFR) is a sign of early-stage coronary artery disease (CAD). Plasma atherogenic index (PAI) is related to atherosclerosis and cardiovascular mortality. Therefore, our aim was to determine CFR and PAI in patients with primary hyperparathyroidism (PHPT) and investigate whether PAI can be used in the detection of early-stage CAD. Material and Methods: The sample was comprised of 44 patients with PTHT and 33 healthy volunteers. We defined CFR as the ratio of the hyperemic diastolic peak velocity to the baseline diastolic peak velocity. PAI values were calculated with the formula of log 10 triglyceride (TRG) / high-density lipoprotein (HDL). Result: The comparison of the groups for PAI and CFR demonstrated that PAI levels were significantly higher while CFR levels were significantly lower in the PTHT patients (p<0.01, p=0.01, respectively). The correlation analysis revealed that CFR was negatively correlated with PAI and TRG (PAI- p<0.0001 r=-0.537).The multivariate logistic regression analysis showed that only a high PAI level (OR: 151.6, 95% confidence interval (CI): 4.1-5480, p=0.006) was an independent predictor of reduction in CFR in PHPT patients. Conclusion: Overall, we found an independent correlation between PAI and CFR values. Hence, PAI may be useful in identifying PHPT patients facing a high risk of adverse cardiovascular events and may also allow early diagnosis of subclinical atherosclerosis.
ARTICLE | doi:10.20944/preprints202310.1545.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: suspension plasma spray; TiO2 coatings; coating microstructures; spray parameters
Online: 25 October 2023 (05:26:47 CEST)
In recent years, there has been growing interest in thermal spray techniques using suspension or solution-based coatings. These techniques offer precise control over particle size and microstructure, improving feedstock flowability and allowing for high-quality coatings customization. Spray parameters, such as stand-off distance (SOD) and feedstock flow rate, can alter the performance and characteristics of these coatings. Geothermal power plant heat exchangers often face issues like corrosion, scaling, and fouling. These issues could be mitigated, at least in part, by the use of spray coatings. In this study, TiO2 coatings were applied to a carbon steel substrate using suspension plasma spray (SPS) to enhance the performance of geothermal heat exchanger materials. The impact of SOD (50, 75, and 100mm) and feedstock flow rate (10, 20, and 30 ml/min) on these coatings was examined through various techniques, including SEM, profilometry, XRD, and adhesion testing. The results demonstrated that coatings deposited using 10ml/min feedstock flow rate were well-adhered to the substrate due to efficient melting of coating material but as the SOD and feedstock flow rate increase due to poor thermal and kinetic energy exchange between the torch and feedstock particles, adhesion between coating and substrate decreases. smaller SODs led to more compact coatings, while higher feedstock flow rates increased coating porosity. Smaller SODs and lower flow rates resulted in well-adhered coatings, offering valuable insights for advancing geothermal heat exchanger coatings.
ARTICLE | doi:10.20944/preprints202310.1166.v1
Subject: Engineering, Metallurgy And Metallurgical Engineering Keywords: plasma electrolytic treatment; nitrocarburizing; tool steel; microhardness; wear resistance
Online: 19 October 2023 (02:49:22 CEST)
The effect of plasma electrolytic nitrocarburizing on the wear resistance of carbon tool steel in friction couples with hardened steel and lead-tin bronze is considered. The microgeometry of friction tracks and its change with increasing duration of friction tests are analyzed. The equilibrium roughness is determined, which is optimal for the friction couple and ensures minimal wear. The type and mechanism of wear of carbon tool steel after plasma electrolytic nitrocarburizing has been determined. The optimal values of the plasma electrolytic nitrocarburizing parameters, which provide the lowest values of the friction coefficient and weight wear, have been determined. The phase and elemental composition of the surface layer was studied using X-ray diffraction analysis and EDX analysis. The relationship of the microstructure of the nitrocarburized layer of tool steel with the friction coefficient and weight wear is established.
ARTICLE | doi:10.20944/preprints202307.1965.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: PTFE; plasma treatment; active gas; N2 gas; surface modification
Online: 28 July 2023 (08:00:09 CEST)
In this paper, we describe the surface modification of Polytetrafluoroethylene (PTFE) through plasma treatment process. Several parameters including different active gases; RF power; dis-tance between the plasma source and sample; and plasma duration were optimized to reduce the hydrophobic nature of PTFE. Three different active gases were used [i.e., N2, O2 and (Ar+H2)], in which N2 was effective to reduce the hydrophobicity of PTFE within shorter plasma duration of 2 minutes. Several surface characterizations including ATR-FTIR, water contact angle, FE-SEM and XPS were utilized to verify the neat and modified PTFE surface after plasma treatment. The plasma treatment using N2 as an active gas improved the wettability of PTFE membrane, show-ing a water contact angle of 108° when compared with the neat PTFE (140°). The SEM images of plasma treated PTFE shows greater modifications on the surface indicating non-uniform fiber alignment and torn fibers at several places. The obtained results confirm the fact that plasma treatment is an effective way to modify the PTFE surface without altering its bulk property.
ARTICLE | doi:10.20944/preprints202307.1291.v1
Subject: Medicine And Pharmacology, Medicine And Pharmacology Keywords: Regenerative medicine; Platelet Rich Plasma; colostrum; growth factors; cytokines
Online: 19 July 2023 (05:42:08 CEST)
The employment of PRP in regenerative medicine has not generated the promised grandiose outcomes. Nonetheless, it currently remains the gold standard strategy for tissue regeneration. Therefore, scientific research has focused on identifying other matrices rich in growth factors and cytokines to improve the efficacy of PRP. In the present study, a new technology called AMPLEX PLUS -compound derived from colostrum enriched with exosomes- was applied in combination with PRP to evaluate the concentration trend of 20 bioactive molecules. The results show that the concentration of all the compounds analyzed increased significantly in PRP samples with AMPLEX PLUS technology compared with samples containing only plasma or PRP, suggesting how this new strategy could improve the performance of PRP and make significant advances in regenerative medicine.
ARTICLE | doi:10.20944/preprints202307.1221.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: Plasma; Ion bombardment; Heat flux; Electron temperature; Electron density
Online: 19 July 2023 (02:42:46 CEST)
Plasma plays an important role in semiconductor processes. With the recent miniature and integration, the control of plasma became essential for the success in critical dimension of a few nanometers and etch narrow and deep holes with high aspect ratios. Recently, the etching process has reached physical limitations due to a significant increase in wafer surface temperature under the elevated amount of RF power, affecting not only the warpage phenomenon but also etching uniformity and etching profiles. Therefore, the plasma characteristics are identified using invasive single Langmuir probe (SLP) for wafer temperature diagnosis. Optical data is obtained through a non-invasive optical emission spectroscopy (OES) and the plasma parameters are derived to compare and verify with the SLP. Two variables, electron temperature and electron density, are substituted for the heat flux formula to derive the heat flux according to its location. Using a wafer-type temperature sensor, check the derived heat flux values and compare trends. Such studies are expected to be able to calculate heat flux values in real time, anticipate wafer temperatures, and solve existing problems.
ARTICLE | doi:10.20944/preprints202306.1266.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: ECMO; Extracorporeal membrane oxygenation; Plasma biomarker; Brain injury; neuromonitoring
Online: 19 June 2023 (03:03:46 CEST)
Background: Early diagnosis of acute brain injury (ABI) is critical for patients on venoarterial extracorporeal membrane oxygenation (VA-ECMO) to guide anticoagulation strategy; however, neurological assessment in ECMO is often limited by patient sedation. Methods: In this pilot study of adults from June 2018 to May 2019, plasma samples of glial fibrillary acidic protein (GFAP), neurofilament light chain (NFL), and Tau were collected daily after VA-ECMO cannulation and measured using a multiplex platform. Primary outcomes were the occurrence of ABI, assessed clinically, and neurologic outcome, assessed by modified Rankin Scale (mRS). Results: Of 20 consented patients (median age=48.5 years; 55% female), 8 (40%) had ABI and 15 (75%) had unfavorable neurologic outcomes at discharge. 10 (50%) patients were centrally cannulated. The median duration on ECMO was 4.5 days (IQR: 2.5-9.5). Peak GFAP, NFL, and Tau levels were higher in patients with ABI vs. without (AUC = 0.77; 0.85; 0.57, respectively) and in patients with unfavorable vs. favorable neurologic outcomes (AUC = 0.64; 0.59; 0.73, respectively). GFAP elevated first, NFL elevated to the highest degree, and Tau showed limited change regardless of ABI. Conclusion: Plasma biomarkers may facilitate early detection of ABIs in VA-ECMO where neurological exam is limited and assist timely clinical decision-making.
ARTICLE | doi:10.20944/preprints202212.0076.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: mechanical alloying; titanium carbide; spark plasma sintering; cermets; corrosion
Online: 5 December 2022 (11:30:50 CET)
In order to produce nanostructured Ti0.9Cr0.1C powders, an elemental powder mixture of titanium, chromium, and graphite is milled in this work using a high-energy ball mill for various milling times. Microstructural characteristics such as crystallite size, microstrain, lattice parameter, and dislocation density are determined using X-ray diffraction (XRD). Mechanical alloying successfully produced nanocrystalline (Ti,Cr)C with an average crystallite size of 11 nm. This size of the crystallites is also directly verified using transmission electron microscopy (TEM). Scanning electron microscopy (SEM) was used to investigate the morphology of the samples. The novelty of this work is advancing the scientific understanding of the effect of milling time on the particle size distribution and crystalline structure, and also understanding the effect of the spark plasma sintering on the different properties of the bulks. Densified cermet samples were produced from the nanocrystalline powders, milled for 5, 10 and 20 hours by SPS process at 1800 degrees for 5 min under a pressure of 80 MPa. Phase changes of the produced cermets were examined according to XRD, SEM/EDX analyses. Significant amounts of Cr and Fe elements were detected, especially in the 20 h milled cermet. The bulk forms of the milled powders for 5 and 20 h had a relative density of 98.43 and 98.51 %, respectively. However, 5 h milled cermet had 93.3 HRA because of the more homogeneous distribution of the (Ti,Cr)C phase, the low iron content and high relative density. According to the 0.0011 mm/year corrosion rate, and 371.68 kΩ*cm2 charge transfer resistance obtained from the potentiodynamic polarization and EIS tests, the 20 h cermet was the specimen with the highest corrosion resistance.
ARTICLE | doi:10.20944/preprints202203.0038.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: polyimide bonding; plasma activation; hydrophilic; hybrid bonding; 3D integration
Online: 2 March 2022 (07:47:17 CET)
Polymer adhesives have emerged as a promising dielectric passivation layer in hybrid bonding for 3D integration while they raise misalignment problems during curing. In this work, the synergistic effect of oxygen plasma surface activation and wetting is utilized to achieve bonding between completed cured polyimides. The optimized process achieves a void-less bonding with a maximum shear strength of 35.3 MPa at a low temperature of 250 °C in merely 2 min, significantly shortening the bonding period and decreasing thermal stress. It is found that the plasma activation generated hydrophilic groups on the polyimide surface, and the wetting process further introduced more -OH groups and water molecular on the activated polyimide surface. The synergistic process of plasma activation and wetting facilitate bridging polyimide interfaces to achieve bonding, providing an alternative path for adhesive bonding in 3D integration.
ARTICLE | doi:10.20944/preprints202201.0105.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: rabbit; biostimulation; reproduction; urine; seminal plasma; chemocommunication; olfaction; pheromones
Online: 10 January 2022 (12:07:54 CET)
Biostimulation is an animal management practice that helps improve reproductive parameters by modulating animal sensory systems. Chemical signals, mostly known as pheromones, have a great potential in this regard. This study was conducted to determine the influence of short-term female rabbit exposure to different conditions, mainly pheromone-mediated, on reproductive parameters of inseminated does. Groups of 60 females/each were exposed to 1) female urine, 2) male urine, 3) seminal plasma and 4) female-female interaction, just before artificial insemination, and compared to isolated females controls (female-female separated). The following reproductive parameters were analyzed for each group: receptivity (vulvar color), fertility (calving rate), prolificacy and number of born alive and dead kits ⁄ litter. Our results showed that the biostimulation methods employed in this experiment did not significantly improve any of the analyzed parameters. However, female doe exposure to urine, especially to male urine, slightly increased fertility levels when compared to the rest of the experimental conditions. Female-female interaction before artificial insemination, which is a common practice in rabbit farms, did not have any effect, which suggests its removal to avoid unnecessary animal management and time cost. On the other hand, fertility ranges were lower for animals with pale vulvar color whereas no differences were noticed among the other three colours which measure receptivity (pink, red, purple), thus suggesting that these three colours could be grouped together. Additionally, equine chorionic gonadotropin injection could be replaced with various biostimulation methods, therefore reducing or replacing current hormonal treatments, and contributing to animal welfare and to a natural image of animal production.
ARTICLE | doi:10.20944/preprints202111.0532.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: Fe-based amorphous coating; AT13; Plasma spraying; Corrosion resistance
Online: 29 November 2021 (12:32:17 CET)
In the present study, the corrosion resistance of amorphous coating and composite coatings in 3.5 wt.% NaCl, 0.5 M H2SO4 and 10 wt.% NaOH solution were studied. The composite coatings exhibit superior corrosion resistance. When the content of AT13 （Al2O3–13 wt.% TiO2）was 15 wt.%, the composite coating has the lowest corrosion current density (1.75×10-6 A cm-2), which is 5.14×10-5 A cm-2 for Fe-based metallic glassy coating, and the highest corrosion potential (-411 mV), which is -580 mV for Fe-based metallic glassy coating. The breakdown potential of the passivation film in 3.5 wt.% NaCl solution was much higher than that of 316L.The long-time immersion corrosion tests carried out on different coatings showed that the corrosion protection effect of coating was enhanced with the increase of the amount of AT13 added.
ARTICLE | doi:10.20944/preprints202103.0289.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: sphingolipidome; ceramides; high resolution mass spectrometry; whole blood; plasma
Online: 10 March 2021 (16:06:08 CET)
Plasma and serum are the most widely used blood-derived biofluids for metabolomics and lipidomics assays, but the isolation of these products from blood may introduce additional bias as indicated by the fact that many analytes that are present at high concentrations in blood cells cannot be measured and evaluated in those samples. Of particular concern, variable hemolysis during the pre-processing of blood products could compromise accurate and reproducible quantification. Compared with plasma or serum, whole blood may be a better alternative due to simplicity of processing. In this study, we provide a comprehensive method for quantification of the whole blood sphingolipidome and the concentrations were compared with those from plasma. Combining a single-phase extraction method with liquid-chromatography high resolution mass spectrometry (R=120, 000), assisted by alkaline hydrolysis, we were able to identify and simultaneously quantify more than 150 sphingolipids. Furthermore, most of sphingolipids remained stable after a freeze/thaw cycle. Whole blood contained a higher concentration of most sphingolipids than corresponding plasma. Moreover, individual variations in the levels of sphingolipids were lower for whole blood than plasma. These findings demonstrate that whole blood could be a better alternative to plasma, and potentially guide the evaluation of sphinglipidome for biomarker discovery.
ARTICLE | doi:10.20944/preprints202011.0316.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: Hydrogen production; Methane cracking; DBD plasma reactor; MgAl2O4; CNTs
Online: 10 November 2020 (13:51:09 CET)
The study experimentally investigated a novel approach for producing hydrogen from methane cracking in dielectric barrier discharge catalytic plasma reactor using a nanocatalyst. Plasma-catalytic methane (CH4) cracking was undertaken in a dielectric barrier discharge (DBD) catalytic plasma reactor using Ni/MgAl2O4. The Ni/MgAl2O4 was synthesised through co-precipitation followed customised hydrothermal method. The physicochemical properties of the catalyst were examined using X-ray diffraction (XRD), scanning electron microscopy - energy dispersive X-ray spectrometry (SEM-EDX) and thermogravimetric analysis (TGA). The Ni/MgAl2O4 shows a porous structure spinel MgAl2O4 and thermal stability. In the catalytic-plasma methane cracking, the Ni/MgAl2O4 shows 80% of the maximum conversion of CH4 with H2 selectivity 75%. Furthermore, the stability of the catalyst was encouraging 16 hours with CH4 conversion above 75%, and the selectivity of H2 was above 70%. This is attributed to the synergistic effect of the catalyst and plasma. The plasma-catalytic CH4 cracking is a promising technology for the simultaneous H2 and carbon nanotubes (CNTs) production for energy storage applications.
ARTICLE | doi:10.20944/preprints202010.0422.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: Plasma heating; tundish; metallurgical effect; inclusions; tundish covering flux
Online: 21 October 2020 (08:46:38 CEST)
Steel products have experienced long-standing problems such as unstable product quality and low product homogeneity. In the continuous casting process, realizing constant temperature pouring is an effective way to improve product homogeneity. Plasma heating can compensate for the temperature drop during casting with a tundish and maintain a stable degree of superheating of the molten steel in the tundish. Plasma heating has a certain impact on the cleanliness of the molten steel and on the tundish covering flux in the tundish while compensating for the temperature drop. This paper uses SEM-EDS, XRD and FactSage to analyze the cleanliness of the molten steel and the characteristics of the tundish covering flux before and after heating. The results show that the number density of inclusions in the tundish is significantly lower after heating, improving the floating removal rate of small-sized inclusions; after heating, the surface morphology of the tundish covering flux sample appears transparent and glassy, with uniform morphology; XRD results show that the tundish covering flux after plasma heating exhibits no crystal precipitation and is amorphous and that there is a certain regularity before and after heating; there are no obvious changes in the composition of the tundish covering flux in the liquid phase area.
ARTICLE | doi:10.20944/preprints202003.0418.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: metamaterials; negative effective mass; plasma oscillations; low frequency plasmons
Online: 29 March 2020 (03:39:01 CEST)
We report the negative effective mass metamaterials based on the electro-mechanical coupling exploiting plasma oscillations of a free electron gas. The negative mass appears as a result of vibration of a metallic particle with a frequency of ω which is close the frequency of the plasma oscillations of the electron gas m_2 relatively to the ionic lattice m_1. The plasma oscillations are represented with the elastic spring k_2=ω_p^2 m_2, where ω_p is the plasma frequency. Thus, the metallic particle vibrated with the external frequency ω is described by the effective mass m_eff=m_1+(m_2 ω_p^2)/(ω_p^2-ω^2 ) , which is negative when the frequency ω approaches ω_p from above. The idea is exemplified with two conducting metals, namely Au and Li.
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: plasma electrolytic oxidation; PEO; coatings; steel; corrosion; zinc-aluminized
Online: 29 March 2020 (01:35:10 CET)
Plasma Electrolytic Oxidation (PEO) is a surface treatment, similar to anodizing, that produces thick oxide films on the surface of metals. In the present work, PEO coatings were obtained on zinc-aluminized (ZA) carbon steel using as electrolyte a solution containing sodium silicate and potassium hydroxide, and working with high current densities and short treatment times in DC mode. The surface morphology resulted the typical one of PEO layers, with the presence of a lot of pores and micro-cracks. Considering the cross section, the thickness of the coating was strongly influenced by the process parameters, with different dissolution grades of the ZA layer depending on the current density and treatment time. The PEO layer resulted mainly composed by aluminum and zinc oxides and silicates. The corrosion resistance was remarkable increased in the samples with the PEO coating.
ARTICLE | doi:10.20944/preprints201803.0200.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: Plasma Electrolytic Oxidation (PEO); Micro Arc Oxidation (MAO); Titanium
Online: 23 March 2018 (15:16:33 CET)
In the paper, the effect of voltage increasing (from 500 VDC up to 650 VDC) on the structure and chemical composition of porous coating on titanium made by Plasma Electrolytic Oxidation, is presented. In the present paper, phosphates based coatings enriched with calcium, magnesium, zinc and copper in electrolyte based on 1 L of 85% concentrated H3PO4 with additions of Ca(NO3)2·4H2O, and Mg(NO3)2∙6H2O, and Zn(NO3)2∙6H2O, and Cu(NO3)2∙3H2O, are described. The morphology, chemical and phase composition, are evaluated using SEM, EDS, XRD, XPS, GDOES. Based on all the analyses, it was found out that the PEO coatings are porous and enriched with calcium, magnesium, zinc and copper. They consist mainly of the amorphous phase, which is more visible for higher voltages, and it is correlated with the increasing of the total PEO coating thickness (the higher the voltage, the thicker the PEO coating). However, for 650 VDC an amorphous phase and titanium substrate was also recorded with a signal from Ti2P2O7 crystalline, that was not observed for lower voltages. It was also found out that all the obtained coatings may be divided in three sub-layers, i.e. porous, semiporous, and transition one.
ARTICLE | doi:10.20944/preprints201801.0057.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: ion plasma treatment; fatigue loading; fracture; polyurethane; surface morphology
Online: 8 January 2018 (09:48:51 CET)
Plasma treatment of soft polymers is the promising technique to improve biomedical properties. The response to the deformation of such materials is not yet clear. Soft elastic polyurethane treated with plasma immersion ion implantation is subjected to fatigue uniaxial loading (50000 cycles, frequency – 1 Hz, strain amplitude – 10, 20, 40%). The influence of the strain amplitude and the plasma treatment regime on damage character is discussed. Surface defects are studied in unloaded and stretched states of the material. As a result of fatigue loading, transverse cracks (with closed overlapping edges as well as with open edges deeply propagating into the polymer) and longitudinal folds which are break and bend inward, appear on the surface. Hard edges of cracks cut the soft polymer which is squeezed from the bulk to the surface.