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Ferguson, Ken R., Maximilian Bucher, Tais Gorkhover, Sébastien Boutet, Hironobu Fukuzawa, Jason E. Koglin, Yoshiaki Kumagai et al. "Transient lattice contraction in the solid-to-plasma transition". Science Advances 2, n. 1 (gennaio 2016): e1500837. http://dx.doi.org/10.1126/sciadv.1500837.
Testo completoAbstract (sommario):
In condensed matter systems, strong optical excitations can induce phonon-driven processes that alter their mechanical properties. We report on a new phenomenon where a massive electronic excitation induces a collective change in the bond character that leads to transient lattice contraction. Single large van der Waals clusters were isochorically heated to a nanoplasma state with an intense 10-fs x-ray (pump) pulse. The structural evolution of the nanoplasma was probed with a second intense x-ray (probe) pulse, showing systematic contraction stemming from electron delocalization during the solid-to-plasma transition. These findings are relevant for any material in extreme conditions ranging from the time evolution of warm or hot dense matter to ultrafast imaging with intense x-ray pulses or, more generally, any situation that involves a condensed matter-to-plasma transition.
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Dorchies, F., e V. Recoules. "Non-equilibrium solid-to-plasma transition dynamics using XANES diagnostic". Physics Reports 657 (ottobre 2016): 1–26. http://dx.doi.org/10.1016/j.physrep.2016.08.003.
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Liu, Chen, Andriani Mentzelopoulou, Fotini Papagavriil, Prashanth Ramachandran, Artemis Perraki, Lucas Claus, Sebastian Barg et al. "SEC14-like condensate phase transitions at plasma membranes regulate root growth in Arabidopsis". PLOS Biology 21, n. 9 (18 settembre 2023): e3002305. http://dx.doi.org/10.1371/journal.pbio.3002305.
Testo completoAbstract (sommario):
Protein function can be modulated by phase transitions in their material properties, which can range from liquid- to solid-like; yet, the mechanisms that drive these transitions and whether they are important for physiology are still unknown. In the model plant Arabidopsis, we show that developmental robustness is reinforced by phase transitions of the plasma membrane-bound lipid-binding protein SEC14-like. Using imaging, genetics, and in vitro reconstitution experiments, we show that SEC14-like undergoes liquid-like phase separation in the root stem cells. Outside the stem cell niche, SEC14-like associates with the caspase-like protease separase and conserved microtubule motors at unique polar plasma membrane interfaces. In these interfaces, SEC14-like undergoes processing by separase, which promotes its liquid-to-solid transition. This transition is important for root development, as lines expressing an uncleavable SEC14-like variant or mutants of separase and associated microtubule motors show similar developmental phenotypes. Furthermore, the processed and solidified but not the liquid form of SEC14-like interacts with and regulates the polarity of the auxin efflux carrier PINFORMED2. This work demonstrates that robust development can involve liquid-to-solid transitions mediated by proteolysis at unique plasma membrane interfaces.
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Wang, Xin-Ke, Igor Veremchuk, Matej Bobnar, Jing-Tai Zhao e Yuri Grin. "Solid solution Pb1−xEuxTe: constitution and thermoelectric behavior". Inorganic Chemistry Frontiers 3, n. 9 (2016): 1152–59. http://dx.doi.org/10.1039/c6qi00161k.
Testo completoAbstract (sommario):
The thermoelectric properties of polycrystalline materials on the basis of the solid solution Pb1−xEuxTe prepared by spark-plasma-sintering are characterized. The solid solution undergoes a metal–semiconductor transition in parallel to the p–n transition around 500 K.
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FISHER, DIMITRI V., ZOHAR HENIS, SHALOM ELIEZER e JUERGEN MEYER-TER-VEHN. "Core holes, charge disorder, and transition from metallic to plasma properties in ultrashort pulse irradiation of metals". Laser and Particle Beams 24, n. 1 (marzo 2006): 81–94. http://dx.doi.org/10.1017/s0263034606060137.
Testo completoAbstract (sommario):
We study the details of a gradual change in electron properties from those of a nearly-free-electron (NFE) metal to those of a strongly-coupled plasma, in ultrashort pulse energy deposition in solid metal targets. Time scales shorter than those of a target surface layer expansion are considered. Both the case of an optical laser (visible or near infrared wavelengths range) and of a free electron laser (vacuum ultraviolet or X-ray) are treated. The mechanisms responsible for the change in electron behavior are isochoric melting, lattice charge disordering, and electron mean free path reduction. We find that the transition from metal to plasma usually occurs via an intermediate stage of a charge-disordered solid (solid plasma), in which ions are at their lattice sites but the ionization stages of individual ions differ due to ionization from localized bound states. Charge disordered state formation is very rapid (typically, few femtoseconds or few tens of femtoseconds). Pathway to charge-disordered state differs in simple metals and in noble metals. Probabilities are derived for electron impact ionization and 3-body recombination of a bound ionic state in solid-density medium, applicable both in metal and in plasma regime. An evolution of energy coupling between electron and ion subsystems, from metallic electron-phonon (e-ph) to plasma electron-ion (e-i) coupling, is considered. Substantial increase in coupling parameter is expected as a result of charge disorder.
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Smirnova, K. V., D. A. Shutov, A. N. Ivanov e V. V. Rybkin. "Plasma-solution synthesis of particles containing transition metals". Journal of Physics: Conference Series 2064, n. 1 (1 novembre 2021): 012096. http://dx.doi.org/10.1088/1742-6596/2064/1/012096.
Testo completoAbstract (sommario):
Abstract The paper proposes a new method for the synthesis of powders containing transition metals using a plasma-solution system. The reactor was an H-shaped glass cell, the two parts of which were separated by a cellophane membrane. A discharge consisting of two discharges - with a liquid cathode and a liquid anode - a high voltage is applied to titanium electrodes located above the surface of the solution. Aqueous solutions of zinc, iron, cadmium, cobalt, nickel, and copper nitrates were used as the liquid phase. Under the action of the discharge on the liquid anode, in the region of contact of the discharge with the solution the formation of a colloidal suspension was observed. The kinetics of the process of synthesis of solid-phase particles in solution under the action of a discharge have been studied. The chemical composition and morphology of the formed solid phase have been established. The mechanisms of chemical reactions occurring in the solution under the action of plasma, and the mechanisms of formation of transition metal oxides in the process of calcining the synthesized powders have been proposed.
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Singh, Swarnima, P. Bandyopadhyay, Krishan Kumar, M. G. Hariprasad, S. Arumugam e A. Sen. "Transition of a 2D crystal to a non-equilibrium two-phase coexistence state". Physics of Plasmas 30, n. 4 (aprile 2023): 043704. http://dx.doi.org/10.1063/5.0139228.
Testo completoAbstract (sommario):
In this paper, we present experimental observation of the transition of a 2D dust crystal to a non-equilibrium solid–liquid phase coexistence state. The experiments have been carried out in an L-shaped dusty plasma experimental device in a DC glow discharge argon plasma environment. Initially, a monolayer crystalline structure is formed, which is later transformed to a two-phase coexistence state using the background neutral pressure as a control parameter. Self-excited horizontal oscillations are found in the center of the monolayer prior to the appearance of the coexistence state. It is observed that a molten center coexists with a solid periphery. Various structural, thermodynamic, and dynamical quantities are used to characterize the phase state. The surface tension at the solid–liquid circular interface is also determined. A detailed parametric study is made to delineate the existence region of such a state. It is found that melting caused at the core is due to the onset of a localized Schweigert instability in the presence of a few stray particles beneath the top layer in that region.
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Rao, Lin, Edward G. Gillan e Richard B. Kaner. "Rapid synthesis of transition-metal borides by solid-state metathesis". Journal of Materials Research 10, n. 2 (febbraio 1995): 353–61. http://dx.doi.org/10.1557/jmr.1995.0353.
Testo completoAbstract (sommario):
A rapid self-sustaining solid-state precursor route to transition-metal borides, boride solid solutions, and boride composites has been developed. Solid-state metathesis (SSM) reactions between transition-metal chlorides and magnesium boride (MgB2) produce crystalline borides and magnesium chloride. Boride solid solutions are formed using mixed chloride precursors. By using a third precursor, such as NaN3, boride-nitride composites are synthesized. The reaction products are characterized by powder x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and inductively coupled plasma atomic absorption spectroscopy. These boride reactions become self-propagating when the adiabatic temperature is greater than the melting point of the by-product salt, MgCl2 (mp 987 K).
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Yeh, F. B., e P. S. Wei. "Effects of Plasma Parameters on the Temperature Field in a Workpiece Experiencing Solid-Liquid Phase Transition". Journal of Heat Transfer 127, n. 9 (27 aprile 2005): 987–94. http://dx.doi.org/10.1115/1.1999653.
Testo completoAbstract (sommario):
The heat transfer characteristics of a workpiece subject to plasma heating and melting are theoretically and systematically studied. Plasma etching, spray deposition, sputtering, cutting and surface treatment, etc., are usually controlled by energy transfer from plasma to workpieces. In this work, the one-dimensional unsteady conduction equation accounting for solid-liquid phase transition with distinct thermal properties in a workpiece is solved. The plasma is composed of a collisionless presheath and sheath on an electrically floating workpiece that partially reflects or secondarily emits ions and electrons. The energy transport from plasma to the surface is kinetically, analytically and exactly calculated from self-consistent velocity distributions of the ions and electrons. The results show that the predicted surface temperature and energy transmission factor agree well with experimental data. The effects of plasma characteristics and thermal parameters of the workpiece on unsteady temperature profiles and thickness of the molten layer in the workpiece are quantitatively provided in this work. Energy released from recombination of the ions and electrons on the surface is found to play the most important role on heating the workpiece. The deviation of surface temperature contributed by recombination energy can be 1000 K.
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Tachibana, K., e Y. Hayashi. "Analysis of the Coulomb-solidification Process in Particle Plasmas". Australian Journal of Physics 48, n. 3 (1995): 469. http://dx.doi.org/10.1071/ph950469.
Testo completoAbstract (sommario):
The Coulomb-solidification process is analysed using Mie-scattering ellipsometry with the assistance of photography and scanning electron microscopy. Spherical monodisperse carbon particles are observed to grow in a methane plasma. The Coulomb-coupling parameter at the liquid-to-solid phase transition is evaluated to be around 200, which is close to the value predicted by a Monte Carlo simulation. The growth of monodisperse particles of pss: size having the same charge favours the formation of a Coulomb solid.
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Neger, T., e H. Jäger. "A Capillary Discharge for Determination of Plasmadiagnostically Relevant Atomic Quantities". Zeitschrift für Naturforschung A 41, n. 9 (1 settembre 1986): 1094–100. http://dx.doi.org/10.1515/zna-1986-0902.
Testo completoAbstract (sommario):
An improved capillary discharge technique renders possible the production of a plasma jet representing a radially symmetric LTE light source. It shows a special capability of producing plasmas of elements or compounds which exist in the solid state under normal conditions. This plasma source is also suited for the investigation of emission lines of ionised atoms. To demonstrate a possible application, relative transition probabilities of some prominent Cullines in the visible are determined and compared with results of other authors.
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Lim, Norleakvisoth, e Michael J. Gordon. "(Invited) Plasma Reforming of Liquid Hydrocarbons". ECS Meeting Abstracts MA2024-01, n. 24 (9 agosto 2024): 1417. http://dx.doi.org/10.1149/ma2024-01241417mtgabs.
Testo completoAbstract (sommario):
Engineering systems that more sustainably use our natural resources is central to both reducing the risks associated with CO2 emissions and making the long-term transition to a more circular, sustainable, and electrified economy. In particular, developing electrically driven technologies to leverage the energy density of liquids to produce clean fuels, e.g., H2, without making CO2, could be game changing. Here, we investigate the potential of directly exciting plasmas in liquid hydrocarbons to create multi-phase reaction environments, i.e., environments where plasma (ionized gas), H2, gaseous and liquid hydrocarbons, and solid carbon are all present simultaneously, to produce H2, unsaturated C2s, and carbon. The ultimate target is direct transformation of liquid hydrocarbons to gaseous H2 and solid, easy-to-separate carbon using electricity that can be provided from any source and/or points of use. This talk will focus on our recent experiments to strike and sustain low and high frequency plasma discharges in liquid hydrocarbon jets to simultaneously generate gaseous H2, C2s, and solid carbon at high rates. Preliminary experiments show that (i) input energy is not wasted in simply vaporizing the liquid - so the system’s specific energy input preferentially drives hydrocarbon cracking; (ii) discharge drive frequency and plasma space time have a big effect on the H2 specific energy requirement (SER) and H2 generation rate, respectively; (iii) feedstock chemistry affects the H2 and C2 products observed; (iv) carbon particulates rapidly form in the liquid hydrocarbon, but they can be separated easily; and (v) the SER for H2 production is 25-30 kWhr/kg, roughly two times less than water electrolysis in practice (60 kWhr/kg). Hydrocarbon conversion, reaction rates, and characterization of the plasma (OES, high speed imaging), gas (MS), liquid (GC/MS), and solid phase (SEM, Raman) products as a function of plasma operating conditions (high and low AC drive frequency; liquid-plasma contact time) and hydrocarbon source will be discussed.
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Norton, Charles D., Viktor K. Decyk, Boleslaw K. Szymanski e Henry Gardner. "The Transition and Adoption to Modern Programming Concepts for Scientific Computing in Fortran". Scientific Programming 15, n. 1 (2007): 27–44. http://dx.doi.org/10.1155/2007/146752.
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This paper describes our experiences in the early exploration of modern concepts introduced in Fortran90 for large-scale scientific programming. We review our early work in expressing object-oriented concepts based on the new Fortran90 constructs – foreign to most programmers at the time – our experimental work in applying them to various applications, the impact on the WG5/J3 standards committees to consider formalizing object-oriented constructs for later versions of Fortran, and work in exploring how other modern programming techniques such as Design Patterns can and have impacted our software development. Applications will be drawn from plasma particle simulation and finite element adaptive mesh refinement for solid earth crustal deformation modeling.
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Khrapak, Sergey, e Alexey Khrapak. "Prandtl Number in Classical Hard-Sphere and One-Component Plasma Fluids". Molecules 26, n. 4 (5 febbraio 2021): 821. http://dx.doi.org/10.3390/molecules26040821.
Testo completoAbstract (sommario):
The Prandtl number is evaluated for the three-dimensional hard-sphere and one-component plasma fluids, from the dilute weakly coupled regime up to a dense strongly coupled regime near the fluid-solid phase transition. In both cases, numerical values of order unity are obtained. The Prandtl number increases on approaching the freezing point, where it reaches a quasi-universal value for simple dielectric fluids of about ≃1.7. Relations to two-dimensional fluids are briefly discussed.
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Trinh, Ngoc Quang, Shinichi Tashiro, Tetsuo Suga, Tomonori Kakizaki, Kei Yamazaki, Ackadech Lersvanichkool, Hanh Van Bui e Manabu Tanaka. "Metal Transfer Behavior of Metal-Cored Arc Welding in Pure Argon Shielding Gas". Metals 12, n. 10 (23 settembre 2022): 1577. http://dx.doi.org/10.3390/met12101577.
Testo completoAbstract (sommario):
The metal transfer behavior of gas metal arc welding in a pure argon shielding gas was evaluated through experiments using a standard solid wire and a metal-cored wire. The investigation was conducted using observation techniques based on recording images by a high-speed camera equipped with laser assistance and bandpass filters in a range of welding currents. It was observed that the metal transfer mode became a streaming transfer mode when the welding current increased in the solid wire. Meanwhile, in the metal-cored wire, the droplet transfer frequency increased, and the droplet diameter decreased without changing the metal transfer mode in the globular transfer mode. We surmised that the streaming transfer in the solid wire would be caused by the spread of argon plasma at the wire tip, which decreases the effect of the electromagnetic force on droplet detachment. Conversely, due to the presence of flux inside the metal-cored wire, the argon plasma could not spread and was attached close to the iron vapor plasma at the overhead of the droplet. Hence, the electromagnetic force acting on the side of the unmelted flux was ineffective at promoting droplet detachment, preventing the transition to a streaming transfer mode. Furthermore, weld bead formation in the metal-cored wire was better than that in a conventional solid wire.
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Rodriguez, Johnnatan, Kevin Hoefer, Andre Haelsig e Peter Mayr. "Functionally Graded SS 316L to Ni-Based Structures Produced by 3D Plasma Metal Deposition". Metals 9, n. 6 (28 maggio 2019): 620. http://dx.doi.org/10.3390/met9060620.
Testo completoAbstract (sommario):
In this investigation, the fabrication of functionally graded structures of SS316L to Ni-based alloys were studied, using the novel technique 3D plasma metal deposition. Two Ni-based alloys were used, a heat resistance alloy Ni80-20 and the solid-solution strengthened Ni625. Different configurations were analyzed, for the Ni80-20 a hard transition and a smooth transition with a region of 50% SS316L/50% Ni80-20. Regarding the structures with Ni625, a smooth transition configuration and variations in the heat input were applied. The effect of the process parameters on the geometry of the structures and the microstructures was studied. Microstructure examinations were carried out using optical and scanning electron microscopy. In addition, microhardness analysis were made on the interfaces. In general, the smooth transition of both systems showed a gradual change in the properties. The microstructural results for the SS316L (both systems) showed an austenite matrix with δ-phase. For the mixed zone and the Ni80-20 an austenite (γ) matrix with some M7C3 precipitates and laves phase were recognized. The as-built Ni625 microstructure was composed of an austenite (γ) matrix with secondary phases laves and δ-Ni3Nb, and precipitates M7C3. The mixed zone exhibited the same phases but with changes in the morphology.
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Li, Xuechen, Xiaotong Lin, Kaiyue Wu, Pengying Jia, Lifang Dong e Junxia Ran. "Plume transition from solid to hollow with increasing the bias value of a sinusoidal voltage applied to an argon plasma jet". Plasma Processes and Polymers 15, n. 4 (2 febbraio 2018): 1700224. http://dx.doi.org/10.1002/ppap.201700224.
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Smirnova, Kristina Valerievna, Polina Aleksandrovna Ivanova, Sergey Igorevich Kartashov, Dmitry Alexandrovich Shutov, Alexander Nikolaevich Ivanov e Vladimir Vladimirovich Rybkin. "Some regularities of plasma-solution synthesis of binary oxide compounds". Materials. Technologies. Design 5, n. 4 (14) (12 dicembre 2023): 135–45. http://dx.doi.org/10.54708/26587572_2023_5414135.
Testo completoAbstract (sommario):
In this paper, we consider the preparation of some double oxides of transition metals, namely (ZnO)0.92 (CdO)0.08, NiOCuO, NiOCo2O, CoFe2O4, NiFe2O4, ZnFe2O4. The synthesis of bimetallic oxide compounds occurred in two stages. First, plasma-solution synthesis of ultrafine particles from solutions of a mixture of nitrates under the action of a DC glow discharge. The second was the high-temperature treatment of the resulting hydroxonitrates and hydroxides. The kinetics of the formation of the solid phase in the solution had an induction period associated with the accumulation of active particles in the solution under the action of the plasma and the change in the intensity of the light transmitted through the solution during the plasma treatment has an exponential decreasing character. The characteristic times of solid phase formation obtained from these dependences decrease with increasing discharge current. As a result of hydrolysis-like processes, hydroxides and hydroxonitrates of the corresponding metals were formed in the solution. This was confirmed by the XRD and EDS data. According to the data of a SEM and DLS, the particles obtained were characterized by two sizes: one was about 100 nm and the other was about 1.5 μm.
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Степанов, Н. П., М. С. Иванов, Л. Э. Степанова e Л. В. Виноградова. "Закономерности поведения температурных зависимостей удельного сопротивления кристаллов твердых растворов (Bi-=SUB=-2-x-=/SUB=-Sb-=SUB=-x-=/SUB=-)Te-=SUB=-3-=/SUB=- (0<x<2)". Физика и техника полупроводников 56, n. 9 (2022): 897. http://dx.doi.org/10.21883/ftp.2022.09.53412.9839.
Testo completoAbstract (sommario):
It is shown that the change in the resistivity of crystals of solid solutions (Bi2-xSbx)Te3 (0<x<2) p-type in the temperature range preceding the onset of intrinsic conductivity is due not only to a change in the static relaxation time, the behavior of which in the temperature range from 80 to 300 K is determined mainly by the scattering of carriers on oscillations crystal lattice, but also by changing the concentration of light holes. The latter is a consequence of the transition of charge carriers from the subzone of heavy holes to the subzone of light holes, as a result of which the concentration of light holes, which make the main contribution to electrical conductivity, decreases with increasing temperature. As a consequence, the plasmon energy proportional to the concentration of charge carriers also decreases with increasing temperature, and the energy of this transition, comparable to the plasmon energy, increases. In this regard, crystals (Bi2-xSbx)Te3 have a specific feature due to the convergence of the plasmon energy and the interband transition, which creates conditions for increasing the intensity of the electron-plasmon interaction. Keywords: thermoelectric materials, bismuth and antimony tellurides, resistivity, interband transitions, plasma of free charge carriers.
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Stepanov N.P., Ivanov M.S., Stepanova L.E. e Vinogradova L.V. "Regularities of behavior of temperature dependences of resistivity of crystals of solid solutions (Bi-=SUB=-2-x-=/SUB=-Sb-=SUB=-x-=/SUB=-)Te-=SUB=-3-=/SUB=- (0<x<2)". Semiconductors 56, n. 9 (2022): 679. http://dx.doi.org/10.21883/sc.2022.09.54214.9839.
Testo completoAbstract (sommario):
It is shown that the change in the resistivity of crystals of solid solutions (Bi2-xSbx)Te3 (0<x<2) p-type in the temperature range preceding the onset of intrinsic conductivity is due not only to a change in the static relaxation time, the behavior of which in the temperature range from 80 to 300 K is determined mainly by carrier scattering on the vibrations of the crystal lattice, but also by changing the concentration of light holes. The latter is a consequence of the transition of charge carriers from the subzone of heavy holes to the subzone of light holes, as a result of which the concentration of light holes, which make the main contribution to electrical conductivity, decreases with increasing temperature. As a consequence, the plasmon energy proportional to the concentration of charge carriers also decreases with increasing temperature, and the energy of this transition, comparable to the plasmon energy, increases. In this regard, crystals (Bi2-xSbx)Te3 have a specific feature due to the convergence of the plasmon energy and the interband transition, which creates conditions for increasing the intensity of the electron-plasmon interaction. Keywords: thermoelectric materials, bismuth and antimony tellurides, resistivity, interband transitions, plasma of free charge carriers.
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Bundschuh, T., T. Wagner, I. Eberhagen, B. Hambsch e R. KÖster. "Detection of biocolloids in aquatic media by Nano-Particle Analyzer". Spectroscopy 19, n. 1 (2005): 69–78. http://dx.doi.org/10.1155/2005/595276.
Testo completoAbstract (sommario):
The Nano-Particle Analyzer (NPA) based on Laser-Induced Breakdown Detection (LIBD) selectively generates and detects plasma events on colloids in aquatic media. Here, it is made use of the fact that the power density required for plasma generation decreases from the gaseous to the solid medium. At an adequate laser pulse energy, plasmas can thus be generated selectively on colloids. The detections of biocolloids by LIBD-based NPA as described in this paper for the first time clearly reveal that the method is well suited for detecting not only non-biological particulate matter in water, but also microorganisms in the transition range between solid and liquid matter. Consequently, the method can be used for online-monitoring, for example of both the non-biological and biological particulate content during the purification, transport and storage of drinking water. It is further possible to monitoronlinecontamination of pure water or process chemicals by biological matter e.g. in biomedical industry.
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Pineau, A., B. Chimier, S. X. Hu e G. Duchateau. "Modeling the electron collision frequency during solid-to-plasma transition of polystyrene ablator for direct-drive inertial confinement fusion applications". Physics of Plasmas 27, n. 9 (settembre 2020): 092703. http://dx.doi.org/10.1063/5.0006116.
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Manchón-Gordón, Alejandro Fernando, Antonio Perejón, Eva Gil-González, Maciej Kowalczyk, Pedro E. Sánchez-Jiménez e Luis A. Pérez-Maqueda. "Low Temperature Magnetic Transition of BiFeO3 Ceramics Sintered by Electric Field-Assisted Methods: Flash and Spark Plasma Sintering". Materials 16, n. 1 (25 dicembre 2022): 189. http://dx.doi.org/10.3390/ma16010189.
Testo completoAbstract (sommario):
Low temperature magnetic properties of BiFeO3 powders sintered by flash and spark plasma sintering were studied. An anomaly observed in the magnetic measurements at 250 K proves the clear existence of a phase transition. This transformation, which becomes less well-defined as the grain sizes are reduced to nanometer scale, was described with regard to a magneto-elastic coupling. Furthermore, the samples exhibited enhanced ferromagnetic properties as compared with those of a pellet prepared by the conventional solid-state technique, with both a higher coercivity field and remnant magnetization, reaching a maximum value of 1.17 kOe and 8.5 10-3 emu/g, respectively, for the specimen sintered by flash sintering, which possesses the smallest grains. The specimens also show more significant exchange bias, from 22 to 177 Oe for the specimen prepared by the solid-state method and flash sintering technique, respectively. The observed increase in this parameter is explained in terms of a stronger exchange interaction between ferromagnetic and antiferromagnetic grains in the case of the pellet sintered by flash sintering.
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Valin, S., Y. Golubovskii, S. Gortschakow e F. Sigeneger. "Influence of radiation transport on discharge characteristics of an atmospheric pressure plasma jet in argon". Plasma Sources Science and Technology 30, n. 12 (1 dicembre 2021): 125003. http://dx.doi.org/10.1088/1361-6595/ac3591.
Testo completoAbstract (sommario):
Abstract In the current work the method of radiation trapping treatment in finite coaxial cylinders using spherical coordinates is introduced. The operator of the resonant transition process is obtained explicitly in matrix form and its response to the delta function is analyzed in both hollow and solid cylinders. The influence of the radiation trapping effect is shown for the example of a model of a miniaturized non-thermal atmospheric pressure plasma jet. The results of the calculations with the developed matrix method (MM) are compared with those based on the effective probability approximation. It is shown that the use of the MM leads to significant spatial redistribution of the excited plasma species due to the non-local effects of the radiation transport mechanism.
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Pert, G. J. "Models of laser-plasma ablation. Part 3. Steady-state theory: deflagration flow". Journal of Plasma Physics 39, n. 2 (aprile 1988): 241–76. http://dx.doi.org/10.1017/s0022377800013015.
Testo completoAbstract (sommario):
The theory of plasma ablation by laser irradiation from cylindrical and spherical solid targets is considered when thermal conduction is dominant and absorption is local at the critical density. Analytic solutions for both inhibited and uninhibited heat fluxes are developed, but only investigated in detail when flux limiting does not introduce a step discontinuity. In most cases it is found that only a restricted region of flow is steady, and must be terminated by a rarefaction wave. The transition from quasi-planar to strongly divergent flow is shown to depend on a characteristic parameter, which represents the ratio of the thermal conduction length to the target radius.
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Bol, Ageeth Anke. "(Invited) Low Temperature Atomic Layer Deposition Processes for Large-Area Synthesis of 2D Transition Metal Dichalcogenides". ECS Meeting Abstracts MA2024-01, n. 12 (9 agosto 2024): 998. http://dx.doi.org/10.1149/ma2024-0112998mtgabs.
Testo completoAbstract (sommario):
2D materials have been the focus of intense research in the last decade due to their unique physical properties. This presentation will highlight our recent progress on the large-area synthesis of two-dimensional transition metal chalcogenides for nanoelectronics using advanced atomic layer deposition cycle schemes. First, how we can use advanced cycle schemes to deposit wafer-scale polycrystalline MoS2 thin films at very low temperatures down to 100 °C. We have identified the critical role of hydrogen during the plasma step in controlling the composition and properties of molybdenum sulfide films. By increasing the H2/H2S ratio or adding an extra hydrogen plasma step to our ALD process, we are able to deposit pure polycrystalline MoS2 films at temperatures as low as 100 °C. To the best of our knowledge, this represents the lowest temperature for crystalline MoS2 films prepared by any chemical gas-phase method.[1] The most dominant methods for preparing MoS2 via ALD is to alternately expose a substrate to a metalorganic precursor and a hydrogen sulfide (H2S) or a plasma containing H2S. H2S is a corrosive, toxic, and flammable gas that is heavier than air, which makes it hazardous and expensive to store, install, and transport. Alternative sulfur precursors in the solid or liquid phase would be beneficial in terms of cost and safety and would require the installation of no additional hardware for most ALD reactors. In the second half of this contribution, the widely researched ALD process using bis(tert-butylimido)bis(dimethylamino)molybdenum(IV) ((tBuN)2(NMe2)2Mo) and H2S plasma is compared to a novel ALD process using (tBuN)2(NMe2)2Mo, hydrogen plasma, and di-tert-butyl disulfide (TBDS), which is an inexpensive, liquid-phase sulfur precursor. [1] M. Mattinen et al., Chem. Mater. (2022), 34, 5104
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Ivanov, Yurii F., Yuriy Kh Akhmadeev, Olga V. Krysina, Nikolai N. Koval, Vladimir V. Shugurov, Elizaveta A. Petrikova, Nikita A. Prokopenko e Oleg S. Tolkachev. "Structure and Properties of Cermet Coatings Produced by Vacuum-Arc Evaporation of a High-Entropy Alloy". Coatings 13, n. 8 (7 agosto 2023): 1381. http://dx.doi.org/10.3390/coatings13081381.
Testo completoAbstract (sommario):
Multilayer cermet coatings based on a TiNbZrTaHf high-entropy alloy were produced on solid substrates by plasma-assisted vacuum-arc deposition. The assisting multicomponent metal-gas plasma was generated by evaporating TiNbZrTaHf cathodes in a gas mixture of nitrogen and argon. It was found that the coatings were nanocrystalline in structure (with nanocrystal sizes ranging from 2.5 to 4 nm). The metallic layer had a body-centered cubic lattice (a = 0.33396 nm), and the ceramic layer had a face-centered cubic lattice (a = 0.44465 nm). Transition layers formed between the substrate and the metallic layer and between the metallic and the ceramic layers were revealed. The hardness of the coatings was 36.7 GPa and their Young’s modulus was 323 GPa.
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Rynearson, Leah, Sophia Tiano, Chamithri Jayawardana, Cali Antolini, Munaiah Yeddala, Dugan Hayes e Brett L. Lucht. "Speciation of Transition Metal Dissolution in Electrolyte from Common Cathode Materials". ECS Meeting Abstracts MA2023-02, n. 2 (22 dicembre 2023): 207. http://dx.doi.org/10.1149/ma2023-022207mtgabs.
Testo completoAbstract (sommario):
Significant capacity loss has been observed across extended cycling of lithium-ion batteries to high temperatures and high voltages. This occurs due to transition metal dissolution from the high voltage spinel or layered oxide cathode material, ion migration through the electrolyte, and deposition on the solid-electrolyte interphase (SEI) on the anode. While much research has been done to track the oxidation state of the transition metal in the cathode material or deposited on the anode, there have been mixed reports on the chemical state of the transition metal ions dissolved in the electrolyte depending on the type of cathode used. X-ray absorption near edge spectroscopy (XANES) was performed on electrolytes extracted from full cells built with four different cathode materials that were cycled at either high or standard voltages to determine the chemical state of Mn and Ni in solution. Inductively coupled plasma-mass spectrometry (ICP-MS) was performed on the anodes from these cells to determine the concentration of deposited metal ions.
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Navarro-García, J. D., J. P. Camarillo-Garcia, F. Alvarado-Hernández, J. L. Sánchez Llamazares e H. Flores-Zúñiga. "Elastocaloric and Magnetocaloric Effects Linked to the Martensitic Transformation in Bulk Ni55Fe11Mn7Ga27 Alloys Produced by Arc Melting and Spark Plasma Sintering". Metals 12, n. 2 (2 febbraio 2022): 273. http://dx.doi.org/10.3390/met12020273.
Testo completoAbstract (sommario):
The investigation of caloric effects linked to first-order structural transitions in Heusler-type alloys has become a subject of considerable current interest due to their potential utilization as refrigerants in solid-state cooling devices. This study is mainly motivated by the possibility of developing refrigeration devices of improved energy efficiency with a reduced environmental impact. We produced partially textured and isotropic bulk samples of the Heusler-type magnetic shape memory alloy Ni55Fe11Mn7Ga27 by arc melting and spark plasma sintering (SPS), respectively. Their structural, microstructural, and phase transition characteristics and magnetocaloric and elastocaloric effects, associated with first-order martensitic transformation (MT), were studied. The elemental chemical compositions of both samples were close to nominal, and a martensitic-like structural transformation appeared around room temperature with similar starting and finishing structural transition temperatures. At room temperature, austenite exhibited a highly ordered L21-type crystal structure. The partial grain orientation and isotropic nature of the arc-melted and SPS samples, respectively, were revealed by X-ray diffraction and SEM observations of the microstructure. For the arc-melted sample, austenite grains preferentially grew in the (100) direction parallel to the thermal gradient during solidification. The favorable effect of the texture on the elastocaloric response was demonstrated. Finally, due to its partial grain orientation, the arc-melted bulk sample showed superior values of maximum magnetic entropy change (|ΔSM|max = 18.6 Jkg−1K−1 at 5 T) and elastocaloric adiabatic temperature change (|ΔTadme|max = 2.4 K at 120 MPa) to those measured for the SPS sample (|ΔSM|max = 8.5 Jkg−1K−1 and (|ΔTadme|max = 0.8 K).
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Baginski, Thomas A., Robert N. Dean e Steven P. Surgnier. "A New Robust One-Shot Switch for High-Power Pulse Applications". Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2011, DPC (1 gennaio 2011): 001650–73. http://dx.doi.org/10.4071/2011dpc-wp21.
Testo completoAbstract (sommario):
High Voltage (HV) switches capable of operating at high speeds and over a wide range of voltages and energies are used in a variety of pulse power applications in material science and plasma physics. Of particular interest is the use of small-scale capacitor discharges to measure the electrical properties of materials as they are heated from solid through liquid to a gas phase. In a capacitive discharge unit (CDU), energy stored in a capacitor is coupled through a switch into a low-impedance transmission line, which typically terminates with a thin sample of material. The energy coupled to the sample is sufficient to cause vaporization. Voltages in such systems range from a few volts to thousands of volts. These vaporized materials are used either as plasma sources for physics experiments, or to propel a thin layer of electrically insulating polymer for high-pressure-impact studies. Several types of switches have been used to drive these systems, including triggered spark gap, dielectric breakdown, and mercury vapor switches. A wide variety of solid-state devices, such as the insulated gate bipolar transistors, are also being utilized for these applications. Inducing a high-pressure shock wave in a dielectric to produce a transition from dielectric to conductor has also been used as an efficient single-shot switch for capacitor discharges. The high-voltage micro-machined switch presented in this document has been designed as a single-use alternative to the more expensive triggered spark gaps and solid-stage devices. The plasma-bridge switch is intended for large-volume, relatively inexpensive systems, and a cost-effective switch for use in destructive testing.
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Lun, Huilin, Yi Zeng, Xiang Xiong, Ziming Ye, Zhongwei Zhang, Xingchao Li, Haikun Chen e Yufeng Liu. "Oxidation behavior of non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution powders in air". Journal of Advanced Ceramics 10, n. 4 (13 luglio 2021): 741–57. http://dx.doi.org/10.1007/s40145-021-0469-y.
Testo completoAbstract (sommario):
AbstractMulti-component solid solutions with non-stoichiometric compositions are characteristics of ultra-high temperature carbides as promising materials for hypersonic vehicles. However, for group IV transition-metal carbides, the oxidation behavior of multi-component non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution has not been clarified yet. The present work fabricated four kinds of (Zr,Hf,Ti)Cx carbide solid solution powders by free-pressureless spark plasma sintering to investigate the oxidation behavior of (Zr,Hf,Ti)Cx in air. The effects of metallic atom composition on oxidation resistance were examined. The results indicate that the oxidation kinetics of (Zr,Hf,Ti)Cx are composition dependent. A high Hf content in (Zr,Hf,Ti)Cx was beneficial to form an amorphous Zr-Hf-Ti-C-O oxycarbide layer as an oxygen barrier to enhance the initial oxidation resistance. Meanwhile, an equiatomic ratio of metallic atoms reduced the growth rate of (Zr,Hf,Ti)O2 oxide, increasing its phase stability at high temperatures, which improved the oxidation activation energy of (Zr, Hf, Ti)Cx.
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Frolov, Sergey M. "Organic Waste Gasification: A Selective Review". Fuels 2, n. 4 (7 dicembre 2021): 556–651. http://dx.doi.org/10.3390/fuels2040033.
Testo completoAbstract (sommario):
This review considers the selective studies on environmentally friendly, combustion-free, allothermal, atmospheric-pressure, noncatalytic, direct H2O/CO2 gasification of organic feedstocks like biomass, sewage sludge wastes (SSW) and municipal solid wastes (MSW) to demonstrate the pros and cons of the approaches and provide future perspectives. The environmental friendliness of H2O/CO2 gasification is well known as it is accompanied by considerably less harmful emissions into the environment as compared to O2/air gasification. Comparative analysis of the various gasification technologies includes low-temperature H2O/CO2 gasification at temperatures up to 1000 °C, high-temperature plasma- and solar-assisted H2O/CO2 gasification at temperatures above 1200 °C, and an innovative gasification technology applying ultra-superheated steam (USS) with temperatures above 2000 °C obtained by pulsed or continuous gaseous detonations. Analysis shows that in terms of such characteristics as the carbon conversion efficiency (CCE), tar and char content, and the content of harmful by-products the plasma and detonation USS gasification technologies are most promising. However, as compared with plasma gasification, detonation USS gasification does not need enormous electric power with unnecessary and energy-consuming gas–plasma transition.
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Lalousis, P., I. B. Földes e H. Hora. "Ultrahigh acceleration of plasma by picosecond terawatt laser pulses for fast ignition of fusion". Laser and Particle Beams 30, n. 2 (9 marzo 2012): 233–42. http://dx.doi.org/10.1017/s0263034611000875.
Testo completoAbstract (sommario):
AbstractA fundamental different mechanism dominates laser interaction with picosecond-terawatt pulses in contrast to the thermal-pressure processes with ns pulses. At ps-interaction, the thermal effects are mostly diminished and the nonlinear (ponderomotive) forces convert laser energy instantly with nearly 100% efficiency into the space charge neutral electron cloud, whose motion is determined by the inertia of the attached ion cloud. These facts were realized only by steps in the past and are expressed by the ultrahigh plasma acceleration, which is more than few thousand times higher than observed by any thermokinetic mechanism. The subsequent application for side-on ignition of uncompressed fusion fuel by the ultrahigh accelerated plasma blocks is studied for the first time by using the genuine two-fluid hydrodynamics. Details of the shock-like flame propagation can be evaluated for the transition to ignition conditions at velocities near 2000 km/s for solid deuterium-tritium.
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Wang, Zhiqiang, Ivan Vladimirovich Ushakov, Ivan Sergeevich Safronov e Jianping Zuo. "Physical Mechanism of Selective Healing of Nanopores in Condensed Matter under the Influence of Laser Irradiation and Plasma". Nanomaterials 14, n. 2 (8 gennaio 2024): 139. http://dx.doi.org/10.3390/nano14020139.
Testo completoAbstract (sommario):
The investigation of the features of laser control over the state of nanoscale objects in solid materials is an urgent task of condensed matter physics. We experimentally established the potential for the simultaneous enhancement of hardness and resistance to surface cracking in a titanium alloy due to selective laser irradiation. The regularities of selective heating near nanopores and the influence of the nanopore system on the features of isotherm propagation have been revealed. A physical model is proposed for the healing of nanopores situated in the surface layer of the sample. According to this model and as a result of laser irradiation and laser plasma, a brief transition of the material surface to extreme conditions is initiated.
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Li, Xin, Weida Xin, Xiaoyi Zheng, Zhen’an Ren, Daqian Sun e Wanli Lu. "Microstructural Characterization and Formation Mechanism of Nitrided Layers on Aluminum Substrates by Thermal Plasma Nitriding". Metals 9, n. 5 (7 maggio 2019): 523. http://dx.doi.org/10.3390/met9050523.
Testo completoAbstract (sommario):
Nitrided layers on 6082 aluminum alloy substrates and 1060 aluminum substrates are formed at atmospheric pressure using thermal nitrogen plasma, which only takes seconds to form a millimeter-level layer. The nitrided layers are composed of aluminum nitride (AlN) and aluminum solid solution phases. Microstructures in these nitrided layers can be divided into three regions from bottom to top: the transition region, the dendrite region, and the lamella region. These regions are formed in sequence. The formation mechanisms and processes of the three regions are discussed in detail. Furthermore, we found that Al melt is transported upward through the voids and the capillaries in the AlN structures, and reacts with N plasma in the melt surface. The growth of the AlN structures promotes this transport. With the increase of N2 flow rates from 1 L/min to 7.5 L/min, both the hardness and the wear resistance of the nitrided layers are improved, and the nitrided layer becomes thicker.
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Shekhovtsov, V. V. "Spectral pyrometry of non-metallic materials at plasma heating, melting and cooling (Tomsk)". Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture 25, n. 5 (25 ottobre 2023): 95–107. http://dx.doi.org/10.31675/1607-1859-2023-25-5-95-107.
Testo completoAbstract (sommario):
Spectral pyrometry of non-metallic materials under plasma heating, melting and cooling is used in nanotechnology, medicine, energy, metallurgy and other industries, where accurate temperature control is required during processing various materials. Purpose: The aim of this work is to create new spectral pyrometry technique for temperature measurement in difficult conditions of material processing and synthesis, such as plasma heating, melting and cooling of non-metallic materials. Methodology/approach: Small-sized spectrometers for diagnostics of heating, melting and cooling of the quartz target using the plasma jet. HPCS300 Mini Spectrometer with the wavelength range of 380 to 780 nm is used to determine the color temperature of the reference radiation source and for fiber optic calibration. The STS-VIS Microspectrometer based on a 1024×1 element CCD photodetector array with the wavelength range of 350 to 800 nm is used to record the emission spectrum of the object. Research findings: Improvement of production processes, fuel and material cost reduction, increase in the efficiency of plants and equipment, reliability and quality improvement of the final product. Value: During the plasma jet and quartz target interaction, three stages are observed: surface deformation, stable temperature of heating, and cooling of the condensed material with phase-transition points of liquid–pyroplastic–solid states.
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Xu, Jin Fu, Xiao Qin Ding, Xiao Yun Han, Hang You, Xian Rui Wang e Cui Liang. "Microstructure and Properties of Ni60 Self-Fluxing Alloy Coatings Fabricated by Spark Plasma Sintering". Applied Mechanics and Materials 52-54 (marzo 2011): 639–46. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.639.
Testo completoAbstract (sommario):
We report the fabrication of Ni60 self-fluxing alloy coatings on the substrate of 45 steel via spark plasma sintering technique. The microstructure and interface bonding of the coatings have been investigated systematically. The results suggest that the as-prepared coatings possess fine grains, little porosity and with hard-phases (CrB, Cr7C3, Ni3B) dispersed within the substrate (γ-Ni). The coatings are jagged and embedded to the substrate due to the elements diffusion during the SPS process. A solid interfacial metallurgy bonding can be achieved between the coating and substrate and the hardness of the coating is ~597.5 HV0.3. The hardness of the transition layer present a gradient distribution ranged from 597.5 HV0.3 to 209.6 HV0.3. The bonding strength between the coating and substrate is measured to be ~710MPa. The volume abrasive wear rate of the coating is ~5.43 × 10-2cm3.
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Botello-Zubiate, María, María Grijalva-Castillo, Daniel Soto-Parra, Renee Sáenz-Hernández, Carlos Santillán-Rodríguez e José Matutes-Aquino. "Preparation of La0.7Ca0.3−xSrxMnO3 Manganites by Four Synthesis Methods and Their Influence on the Magnetic Properties and Relative Cooling Power". Materials 12, n. 2 (19 gennaio 2019): 309. http://dx.doi.org/10.3390/ma12020309.
Testo completoAbstract (sommario):
Manganites of the family La0.7Ca0.3−xSrxMnO3 were fabricated by four preparation methods: (a) the microwave-assisted sol-gel Pechini method; (b) sol-gel Pechini chemical synthesis; (c) solid-state reaction with a planetary mill; and (d) solid-state reaction with an attritor mill, in order to study the effect of the preparation route used on its magnetocaloric and magnetic properties. In addition, the manganites manufactured by the Pechini sol-gel method were compacted using Spark Plasma Sintering (SPS) to determine how the consolidation process influences its magnetocaloric properties. The Curie temperatures of manganites prepared by the different methods were determined in ~295 K, with the exception of those prepared by a solid-state reaction with an attritor mill which was 301 K, so there is no correlation between the particle size and the Curie temperature. All samples gave a positive slope in the Arrot plots, which implies that the samples underwent a second order Ferromagnetic (FM)–Paramagnetic (PM) phase transition. Pechini sol-gel manganite presents higher values of Relative Cooling Power (RCP) than the solid-state reaction manganite, because its entropy change curves are smaller, but wider, associated to the particle size obtained by the preparation method. The SPS technique proved to be easier and faster in producing consolidated solids for applications in active magnetic regenerative refrigeration compared with other compaction methods.
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Chen, Zhan-Bin. "Electron-impact excitation of atoms or ions with the screened Coulomb potential". Physics of Plasmas 30, n. 3 (marzo 2023): 032103. http://dx.doi.org/10.1063/5.0140534.
Testo completoAbstract (sommario):
This paper reports the development of a novel distorted wave approach based on the relativistic configuration interaction theory for calculating atomic structures, radiative properties, and collision dynamics of atoms or ions under external confinement. Due to its physical interpretations, the Hulthén potential, valid for many important areas (widely plasma environments) in physics and chemistry, such as atomic physics, solid-state physics, nuclear physics, particle physics, and astrophysics, is used to include the effect of plasma background. The Breit interaction and quantum electromagnetic dynamics effects are perturbatively included in the multi-electron Hamiltonian. Wave functions of bound and continuous states are obtained, which are analyzed by means of the Dirac equations. Interparticle interactions in the scattering matrix element of the system are described by the screened Coulomb interactions. As a test desk, the present approach is applied to the calculation of atomic structures and collision dynamics of an exemplary He-like S14+ ion embedded in a plasma. The energy eigenvalues, transition probabilities, and excitation cross sections are analyzed in detail in terms of the screening parameter. The results of the verification cases are compared to references from the literature, which show a good agreement. The present study not only opens up an opportunity to provide a simple and effective way for understanding the plasma shielding models for many-electron systems but also has important implications for a wide range of applications in astrophysics and laboratory plasma experiments.
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de Brito Simões, Jackson, Francisco Fernando Roberto Pereira, Jorge Otubo e Carlos José de Araújo. "Influence of Heat Treatments on a NiTi Shape Memory Alloy Obtained Using Vacuum Induction Melting and Reprocessed by Plasma Skull Push-Pull". MRS Proceedings 1765 (2015): 121–26. http://dx.doi.org/10.1557/opl.2015.817.
Testo completoAbstract (sommario):
ABSTRACTShape memory alloys (SMA) are metallic attractive engineering materials due to their capacity to store pre-defined shapes through a thermally induced phase transition from a solid state. This paper aims to evaluate the influence of solubilization thermal treatments on a NiTi shape memory alloy originally fabricated by vacuum induction melting and then reprocessed by plasma melting followed by injection molding (Plasma Skull Push Pull process) into different metal molds (steel, aluminum, brass and copper) in order to compare the thermal properties regarding to its raw state. The thermal treatments of solubilization were carried out at 850°C in different times (2n function, n = 0, 1, 2 and 3, in hours). The influence of solubilizing treatments in the NiTi shape memory alloy was analyzed using the following characterization techniques: Differential Scanning Calorimetry (DSC) and Electrical Resistance as a function of Temperature (ERT). The results demonstrate that the solubilization heat treatments applied on the reprocessed NiTi shape memory alloy through the plasma skull push pull process, provides important changes in the phase transformation of the material. Therefore, it was demonstrated that it is necessary to solubilize the material after melting or remelting the NiTi shape memory alloy via this process to obtain mini-actuators products with homogeneous properties.
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Sigaev, V. N., A. S. Naumov, V. I. Savinkov, A. S. Lipatiev, S. V. Lotarev, N. N. Klimenko e E. V. Lopatina. "FEATURES OF CRYSTALLIZATION OF LITHIUM-ALUMINOSILICATE GLASS MICROSPHERES OBTAINED IN A HIGH-TEMPERATURE PLASMA FLOW". Steklo i Keramika, n. 5 (maggio 2022): 3–9. http://dx.doi.org/10.14489/glc.2022.05.pp.003-009.
Testo completoAbstract (sommario):
The influence of the spheroidization process in the flow of high-temperature plasma of glass based on the Li2O–Al2O3–SiO2 (LAS) system doped with 1.0 mol. % Nd2O3 on its crystallization properties is investigated. The resulting microspheres with a size of 32 – 64 ?m are characterized by a significantly higher glass transition temperature Tg compared to the Tg of the initial glass (751 °C and 677 °C, respectively), which may be due to both a change in chemical composition during spheroidization and a fundamentally different thermal history of microspheres and glass. Despite the delayed crystallization kinetics, the glass-ceramic structure based on ?-eucryptite-like solid solutions of LixAlxSi1 – xO2 is formed in microspheres, as in the initial glass, under the action of heat treatment, indicating the possibility of both obtaining microspheres with the glass-ceramic structure and varying their coefficient of thermal expansion near zero values.
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Wattamwar, Tejas, Ashish Mungantiwar, Supriya Halde e Nancy Pandita. "Development of simultaneous determination of empagliflozin and metformin in human plasma using liquid chromatography–mass spectrometry and application to pharmacokinetics". European Journal of Mass Spectrometry 26, n. 2 (1 ottobre 2019): 117–30. http://dx.doi.org/10.1177/1469066719879297.
Testo completoAbstract (sommario):
A rapid and sensitive liquid chromatography–mass spectrometry method was developed, optimized, and validated for simultaneous quantification of empagliflozin and metformin in human plasma using empagliflozin D4and metformin D6 as an internal standard. Analytes and internal standard were extracted from plasma by optimized solid-phase extraction technique using Strata X polymeric reverse phase (30 mg-1cc) solid-phase extraction cartridges. The prepared samples were chromatographed on Orosil C18 column (150 × 4.6 mm, 3 µ). Separation was done by pumping isocratic mobile phase consisting of methanol and 10 mM ammonium trifluoroacetate (90:10, v/v) in positive ion mode at a flow rate of 0.8 mL/min. The API 3200 liquid chromatography–mass spectrometry system having turbo ion spray as an ion source coupled with Shimadzu Prominence ultrafast liquid chromatography system was operated under the selected reaction monitoring mode. Turbo ion spray ionization was used for mass transition of m/z 468.070/355.100 and m/z 130.072/71.200 for empagliflozin and metformin, respectively. A method was successfully validated for concentration range of 10.09–5013.46 ng/mL for both the analytes and according to the United States Food and Drugs Administration guidelines. The linearity was found to be in the range of 10.09–403.46 ng/mL for empagliflozin and 25.44–5013.46 ng/mL for metformin. The limit of quantification was found to be 10.09 ng/mL for empagliflozin and 25.44 ng/mL for metformin. Intra- and inter-day/between batch precision determination for empagliflozin and metformin, expressed as coefficient of variation were within the acceptance limits and ranged below 13.16%. A short run time of 3.3 min allows analysis of more than 400 plasma samples per day. The developed method was successfully applied to fasting pharmacokinetic study in healthy human volunteers. Results of incurred sample re-analysis were within the acceptance range of ±20% of original value, for 97.2% of samples reanalyzed for empagliflozin and 100% of samples reanalyzed for metformin.
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Savinkov, Nikolay A., Oleh M. Bulanchuk e Aleksander A. Bizyukov. "The Impact of Pulse Plasma Treatment on the Operating Characteristics of Steel 40X10C2M: Experiment and Numerical Simulations". 3, n. 3 (28 settembre 2021): 102–9. http://dx.doi.org/10.26565/2312-4334-2021-3-16.
Testo completoAbstract (sommario):
This paper presents a study of operating characteristics of steel 40X10C2M after treatment it of high-energy plasma pulses. The steel is used to manufacture the elements of ships' power plants. For pulsed plasma treatment of steel samples, we used an electrothermal plasma accelerator (ETPA). A high-current pulsed high-pressure arc discharge was initiated in a restricted dielectric chamber of ETPA. The discharge duration was 1.4 ms, the maximum current reached the value of 5 kA, the discharge voltage was up to 5 kV. We investigated the microhardness and microstructure of the processed (modified) layer and determined the optimal parameters of steel processing that provide the best characteristics of the modified layer when the microhardness increases by ≈ 5 times. Microhardness maxima were discovered in the depth of the modified layer. The paper studies the possibilities of controlling the maxima localization to form the desired performance characteristics of the treated layer. Mathematical modeling of rapid pulsed heating of the steel surface layer is performed within the framework of the two-phase "melt-solid" model, taking into account the dynamics of the thermodynamic characteristics of steel. For this purpose, we used the classical equation of thermal conductivity with varying steel parameters: density, heat capacity, and coefficient of thermal conductivity during the transition of a substance from the liquid to the solid phase. Within the chosen mathematical model, numerical calculations of the rapidly pulsed heating phenomenon of the steel surface were performed, taking into account melting and solidification in the Comsol Multiphysics package using the finite element method. The numerical simulation results are in good agreement with the experimental distribution of the microhardness of the treated steel layer deep into the sample.
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Mościcki, Tomasz, Rafał Psiuk, Joanna Radziejewska, Maria Wiśniewska e Dariusz Garbiec. "Properties of Spark Plasma Sintered Compacts and Magnetron Sputtered Coatings Made from Cr, Mo, Re and Zr Alloyed Tungsten Diboride". Coatings 11, n. 11 (10 novembre 2021): 1378. http://dx.doi.org/10.3390/coatings11111378.
Testo completoAbstract (sommario):
To enhance the properties of tungsten diboride, we have synthesized and characterized solid solutions of this material with chromium, molybdenum, rhenium and zirconium. The obtained materials were subsequently deposited as coatings. Various concentrations of these transition metal elements, ranging from 0.0 to 24.0 at.%, on a metals basis, were made. Spark plasma sintering was used to synthesize these refractory compounds from the pure elements. Elemental and phase purity of both samples (sintered compacts and coatings) were examined using energy dispersive X-ray spectroscopy and X-ray diffraction. Microindentation was utilized to measure the Vickers hardness. X-ray diffraction results indicate that the solubility limit is below 8 at.% for Mo, Re and Zr and below 16 at.% for Cr. Above this limit both diborides (W,TM)B2 are created. Addition of transition metals caused decrease of density and increase of hardness and electrical conductivity of sintered compacts. Deposited coatings W1−xTMxBy (TM = Cr, Mo, Re, Zr; x = 0.2; y = 1.7–2) are homogenous, smooth and hard. The maximal hardness was measured for W-Cr-B films and under the load of 10 g was 50.4 ± 4.7 GPa. Deposited films possess relatively high fracture toughness and for WB2 coatings alloyed with zirconium it is K1c = 2.11 MPa m1/2.
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Okovity, V. A., F. I. Panteleenko, V. V. Okovity, V. M. Astashinsky, V. V. Uglov, V. I. Chimanskiy e N. N. Cerenda. "Formation and Investigation of Plasma Powder Coatings Made of Oxide Ceramics Modified with High-Energy Effects". Science & Technique 17, n. 5 (12 ottobre 2018): 378–89. http://dx.doi.org/10.21122/2227-1031-2018-17-5-378-389.
Testo completoAbstract (sommario):
The paper presents results of studying structure and properties of multilayer composite coatings optimized for their composition based on zirconium dioxide materials used for deposition of plasma coatings on the models of elements for anti-meteor shielding screens. The influence of plasma jet parameters (current, distance of sputtering, consumption of plasma-forming nitrogen gas) and fractional composition of an initial powder on characteristics of two-layer composite coatings based on nickel-chromium-aluminum-yttrium and zirconium dioxide on the elements of protective screens has been analyzed in the paper. Optimization has been carried out on the basis of obtaining maximum coefficient of powder utilization. The investigations have made it possible to ascertain specific features of elemental and phase composition, surface morphology, microstructure multilayer composite coatings on the basis of a solid layer of metal oxides and a viscous transition sub-layer subjected to compression plasma flows. The investigations have been executed with the help of scanning electron microscopy, energy dispersive x-ray spectral microanalysis, and x-ray diffraction analysis. It has been shown on the basis of the obtained results that the effect of compression plasma flows on multilayer composite coatings leads to a modification of a near-surface layer with a thickness up to 15 μm that presupposes its melting and subsequent high-speed crystallization which together provide an increase in its density, decrease in porosity while maintaining the initial phase state. Liquid-phase processes in the molten phase of the near-surface layer permit to modify morphological properties of the surface which are associated with its smoothing and lowering of roughness.
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Koval, Olga Yu, Vladimir V. Fedorov, Alexey D. Bolshakov, Sergey V. Fedina, Fedor M. Kochetkov, Vladimir Neplokh, Georgiy A. Sapunov et al. "Structural and Optical Properties of Self-Catalyzed Axially Heterostructured GaPN/GaP Nanowires Embedded into a Flexible Silicone Membrane". Nanomaterials 10, n. 11 (23 ottobre 2020): 2110. http://dx.doi.org/10.3390/nano10112110.
Testo completoAbstract (sommario):
Controlled growth of heterostructured nanowires and mechanisms of their formation have been actively studied during the last decades due to perspectives of their implementation. Here, we report on the self-catalyzed growth of axially heterostructured GaPN/GaP nanowires on Si(111) by plasma-assisted molecular beam epitaxy. Nanowire composition and structural properties were examined by means of Raman microspectroscopy and transmission electron microscopy. To study the optical properties of the synthesized nanoheterostructures, the nanowire array was embedded into the silicone rubber membrane and further released from the growth substrate. The reported approach allows us to study the nanowire optical properties avoiding the response from the parasitically grown island layer. Photoluminescence and Raman studies reveal different nitrogen content in nanowires and parasitic island layer. The effect is discussed in terms of the difference in vapor solid and vapor liquid solid growth mechanisms. Photoluminescence studies at low temperature (5K) demonstrate the transition to the quasi-direct gap in the nanowires typical for diluted nitrides with low N-content. The bright room temperature photoluminescent response demonstrates the potential application of nanowire/polymer matrix in flexible optoelectronic devices.
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Choi, Yong Gyu, Kee-Sun Sohn, Kyong Hon Kim e Hee Dong Park. "Tb L3-edge X-ray Absorption Near-edge Structure Spectroscopic Analysis of Terbium-doped Phosphor Compoundsfor Plasma Display Panel Applications". Journal of Materials Research 17, n. 1 (gennaio 2002): 31–35. http://dx.doi.org/10.1557/jmr.2002.0007.
Testo completoAbstract (sommario):
We have analyzed Tb L3-edge x-ray absorption near-edge structure spectra of Tb-doped phosphor compounds for plasma display panel applications. Intensity and lifetime of the green emission from the Tb3+:5D4→7F5 transition were measured with respect to nominal terbium concentration in the host compounds, i.e., YBO3, YPO4,and Y4Al2O9, all of which were made through the solid-state reaction. Typical concentration quenching was evident on the fluorescence intensity and the fluorescing level lifetime in our samples. From the analyses of white line absorption peaks at TbL3-edge, it was verified that terbium is essentially trivalent in all the samples, even invery highly concentrated ones. Thus, this implies that the concentration quenching was not caused by presence of mixed-valent states of terbium. Instead, it is believed that anonradiative energy transfer route among Tb3+ ions might be responsible for thebehavior.
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Vardavoulias, Michail, Paraskevi Gkomoza, Michael Arkas, Dimitrios K. Niakolas e Stylianos G. Neophytides. "Thermal Spray Multilayer Ceramic Structures with Potential for Solid Oxide Cell Applications". Coatings 11, n. 6 (5 giugno 2021): 682. http://dx.doi.org/10.3390/coatings11060682.
Testo completoAbstract (sommario):
The objective of this paper is to manufacture free-standing solid oxide cells (SOCs) through the atmospheric plasma spray process (APS), without the aid of a metallic support nor the need for a post-process heating treatment. A five-layered cell was fabricated. Fused and crushed yttria-stabilized zirconia (YSZ) powder in the 5–22 μm particle size range was used in order to achieve a dense electrolyte layer, yet still permitting satisfactory ionic diffusivity. Nickel oxide (NiO) powder that was obtained by in-house flame spray (FS) oxidation of pure nickel (Ni) powder was mixed and sprayed with the original Ni-YSZ feedstock, so as to increase the porosity content in the supporting electrode. Two transition layers were sprayed, the first between the support electrode and the electrolyte (25% (Ni/NiO)–75% YSZ) and the second at the electrolyte and the end electrode interface (50% YSZ–50% lanthanum strontium manganite (LSM)). The purpose of intercalation of these transition layers was to facilitate the ionic motion and also to eliminate thermal expansion mismatches. All the as-sprayed layers were separately tested by an in-house developed acetone permeability comparative test (APCT). Electrodes with adequate porosity (25–30%) were obtained. Concerning electrolytes, relatively thick (150–200 µm) layers derived from fused and crushed YSZ were found to be impermeable to acetone, while thinner YSZ counterparts of less than 100 µm showed a low degree of permeability, which was attributed mostly to existent microcracks and insufficient interparticle cohesion, rather than to interconnected porosity.
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В.М., ЕЛЬКИН, МИХАЙЛОВ В.Н. e ОВЕЧКИН А.А. "МНОГОФАЗНОЕ ШИРОКОДИАПАЗОННОЕ УРАВНЕНИЕ СОСТОЯНИЯ МЕДИ". Физика горения и взрыва 60, n. 6 (29 novembre 2024): 74–85. http://dx.doi.org/10.15372/fgv2023.9363.
Testo completoAbstract (sommario):
Представлено полуэмпирическое многофазное уравнение состояния (УРС) меди для двух твердых ГЦК-, ОЦК-фаз и жидкой фазы с учетом испарения. Для параметризации УРС использован широкий набор экспериментальных и теоретических данных. В области плазменных состояний вещества проведены расчеты по модели среднего атома RESEOS, которые также использованы при разработке УРС. Построены кривые фазового перехода ГЦК — ОЦК, плавления и перехода жидкость — пар. В целом расчеты по УРС хорошо согласуются с экспериментальными данными и результатами теоретических расчетов в широкой области температур и давлений. This paper presents a semi-empirical multiphase equation of state (EOS) of copper for two solid FCC and BCC phases, as well as a liquid phase with account for vaporization is presented. A wide range of experimental and theoretical data is used to parameterize the EOS. In the field of plasma states of matter, calculations are performed using the RESEOS average atom model and are also applied to develop the EOS. Curves are plotted for FCC-BCC phase transition, for melting, and for liquid-vapor transition. In general, the EOS-based calculations are in good agreement with the experimental data and the results of theoretical calculations in a wide range of temperatures and pressures.
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Harutyunyan, Arus, e Armen Sedrakian. "Thermal Conductivity and Thermal Hall Effect in Dense Electron-Ion Plasma". Particles 7, n. 4 (11 novembre 2024): 967–83. http://dx.doi.org/10.3390/particles7040059.
Testo completoAbstract (sommario):
In this study, we examine thermal conductivity and the thermal Hall effect in electron-ion plasmas relevant to hot neutron stars, white dwarfs, and binary neutron star mergers, focusing on densities found in the outer crusts of neutron stars and the interiors of white dwarfs. We consider plasma consisting of single species of ions, which could be either iron Fe56 or carbon C12 nuclei. The temperature range explored is from the melting temperature of the solid T∼109 K up to 1011 K. This covers both degenerate and non-degenerate electron regimes. We find that thermal conductivity increases with density and temperature for which we provide analytical scaling relations valid in different regimes. The impact of magnetic fields on thermal conductivity is also analyzed, showing anisotropy in low-density regions and the presence of the thermal Hall effect characterized by the Righi–Leduc coefficient. The transition froma degenerate to non-degenerate regime is characterized by a minimum ratio of thermal conductivity to temperature, which is analogous to the minimum observed already in the case of electrical conductivity. We provide also formulas fit to our numerical results, which can be used in dissipative magneto-hydrodynamics simulations of warm compact stars.