Powders In Plasma Research Articles

Comparative pharmacokinetics of five primary constituents in Huai-hua powder: a study on normal rats and rats with ulcerative colitis.

The goal of this research was to develop a fast, reliable, and sensitive method to simultaneously quantify five key components of Huai-hua Powder (HHP) in rat plasma with genistein served as the internal standard. Furthermore, the established method was used to perform a comparative evaluation of the pharmacokinetic properties of HHP in normal rats and rats with ulcerative colitis (UC). Chromatographic separation was conducted using an ACQUITY HSS T3 column held at a constant temperature of 35°C, with acetonitrile and a 0.1% formic acid solution in water employed as the mobile phases. Multiple-reaction monitoring facilitated MS operation in positive-negative-ion-switching mode. The method's validation demonstrated exceptional linearity (with a correlation coefficient of r ≥ 0.9970), and the validation tests, encompassing precision within and between days, accuracy, recovery, matrix effect, and stability; all met the predefined acceptable criteria. The results revealed significant variations in the pharmacokinetic characteristics of the five components between normal and UC rats, suggesting altered drug metabolism rates and extents in the latter group. These findings offer crucial scientific insights into the potential clinical application of HHP, particularly in the context of treating UC.

Reduction Kinectics of Hematite Powders in Non-Equilibrium Hydrogen Plasma

Reduction Kinectics of Hematite Powders in Non-Equilibrium Hydrogen Plasma

Structure and luminescence properties of EuF3 and SrF2:Eu nanoparticles after microwave plasma annealing in "methane-hydrogen".

Recently, progress has been made in fabricating diamond-based scintillators with integrated rare-earth luminescent particles. These luminescent particles are integrated into the bulk of diamond during their synthesis by chemical vapor deposition (CVD). However, the growth conditions include a chemically aggressive plasma environment and elevated temperatures, which results in the partial degradation of particles and a decrease in the intensity of their luminescence. Here, we investigate the effect of thermal annealing of luminescent EuF3 and SrF2:Eu powders in microwave plasma that simulates the growth conditions of polycrystalline diamond. It was found that silicon substrates act as efficient reducing agents that lead to the partial reduction of trivalent europium to divalent europium. When annealing occurs on a diamond substrate, the reduction processes proceed at a significantly slower rate. The observed luminescence spectra showed both Eu2+ and Eu3+ luminescence bands, which allows for a targeted tuning of the luminescence spectrum of europium in composites and can be used to fabricate detectors and visualizers of X-ray radiation using a visible signal from the desired combination of Eu2±/Eu3± ions. During plasma annealing in pure hydrogen at moderate temperatures (600 °C), an intensive hydrogenation of particles is observed. Such hydrogen plasma treatment of fluorides may be considered a promising route to fabricate hydrides of various metals.

Synthesis of magnesium oxide and zinc oxide powders in a glow discharge plasma at atmospheric pressure

Investigation of the processes involved in the synthesis of magnesium oxide and zinc oxide powders using the thermal effects of an atmospheric-pressure glow discharge plasma in an inert gas flow are described. The discharge operates in a repetitively pulsed mode with pulse repetition rate of several tens of kilohertz and pulse duration up to 12 μs, discharge current of 600 mA and voltage up to 300 V. These parameters lead to thermal erosion of magnesium or zinc inserts in a molybdenum crucible. The chemical and phase composition of the erosion products were determined using TEM/EDS and X-ray diffraction analysis, and the composition of the plasma was assessed by optical emission spectrometry. This experimental approach allows fabrication of powders of these metal oxides with characteristic particle size 10–50 nm, and the formation of coatings of these materials in a one-step process.

Production of Titanium Carbide Powder in Atmospheric Arc Discharge Plasma and Sintering of Volume Sample of Carbide Ceramics on Its Basis

Production of Titanium Carbide Powder in Atmospheric Arc Discharge Plasma and Sintering of Volume Sample of Carbide Ceramics on Its Basis

Three-dimensional numerical simulation of heating and melting behaviors of cerium oxide powders in radio frequency thermal plasma

The present study aims at the numerical simulations of the melting process of cerium oxide particles in RF thermal plasma. The physical model and the calculating method were described firstly; the interaction between cerium oxide particles and plasma was analyzed; specific attention was given to the effects of particle initial size, injection velocity on the particle melting and trajectory in plasma. The influence of the temperature field and velocity field distribution of the plasma around the particle trajectory on the melting effect is analyzed, and the relationship between the heat absorption efficiency of the particles and the particle size reduction process is further determined. It is also found that there exists an optimal particle initial injection velocity which led to a more concentrated final particle size distribution and a more significant reduction of particle size. The results could provide effective guidance for understanding the plasma spheroidization process of uranium dioxide and cerium dioxide powder particles.

Структурные изменения плазменных покрытий гидроксиапатита в зависимости от мощности плазмы

The structure of hydroxyapatite (HA) plasma coatings obtained by changing the power of the plasma torch (P) from 20 to 26 kW was studied by X-ray diffraction analysis. All coatings contained the decomposition products of hydroxyapatite in the plasma flow, phases of tetracalcium phosphate (TTCP) and CaO. Their number, which increases with increasing P and plasma temperature (Tp), is determined by the partial loss of phosphorus by the initial HA powder in plasma and the shift in the chemical composition of the coating to higher calcium contents. An increase in P and Tp is accompanied by an increase in the intensity of the HA basic texture. In the range of 24 < P < 26 kW, the intensity ratio of X-ray reflections HA δ = I(200)/I(211) exceeds 3.0 in its value, while at P = 20 kW δ <1.5. The presence of orientation relationships between the predominant crystallographic orientations of HA and TTCP crystals in coatings is associated with the similarity of their structures, the proximity of lattice periods, and the presence of identical fragments in their structures. The possibility of the formation of mixed-layer structures involving these compounds is discussed. The following factors are considered as the factors that have the greatest influence on the nature of the dependences obtained: the substrate temperature, the particle size in the initial HA powder, and the composition of the plasma gases.

Mechanical activation of fullerene containing soot during extraction of higher and endohedral metallofullerenes

For extraction of higher fullerenes and endohedral metallofullerenes (EMF) with yttrium from fullerene-containing carbon soot (soot) obtained by combined spraying of graphite and yttrium oxide powders in an arc plasma, we developed a device (Extractor*) that provides mechanical activation effects on agents combined with filtration. It has been shown that the soot recovery percentage of a mixture of higher fullerenes and EMF with different solvents (carbon disulfide, o-xylene, pyridine) and the EMF mass fraction in the mixture is significantly higher than in the extraction with a Soxhlet apparatus traditionally used for these purposes. The time spent on the extraction process is reduced significantly. Due to a known reaction with titanium chloride (TiCl4) and removal of a solution of empty fullerenes, subsequent bonding of EMF with yttrium into an insoluble complex directly in the extractor allows the product to be significantly enriched with EMF. In general, we were able to significantly reduce both the duration of extraction of the fullerenes mixture and EMF and the production of EMF separately. Highlights A mechanical extractor (Extractor*) developed by us, which allows processing a larger amount of carbon black and, accordingly, extracting more fullerenes per unit of time, has been applied. The percentage of extraction from the soot of a mixture of higher fullerenes and EMF with various solvents was significantly higher than with extraction using the Soxhlet apparatus. It has been shown that mechanical extractor using makes it possible to increase the coefficient of mass transfer from the surface of the particles to the extracting agents. The Extractor* was first used for the non-HPLC separation of endohedral metallofullerenes with TiCl4. The use of the new device made it possible to isolate a product significantly enriched in endohedral metallofullerenes.

Ash Waste Utilization via Direct Current Arc Plasma with Production of SiC and AlN

Ash accumulation is a relevant problem due to the widespread use of coal-fired power plants and a very limited number of ash utilization technologies. Plasma processing of ash is a promising method of ash valorization for production of various useful products, which is limited by high energy consumption. In the current study, a mixture of waste ash from power plant and black carbon was processed using an original direct current plasma arc experimental setup in ambient air which allows lower energy consumption due to the absence of the vacuuming system. Four types of samples at different plasma exposure times were produced and together with the initial ash were studied by thermal analysis, X-ray diffractometry and scanning electron microscopy. The X-ray diffraction analysis identified the resulting phases of graphite, silicon carbide, and aluminum nitride in the synthesis products; at the same time, at the arc discharge energy increased from 26 to 105 kJ, the intensities of the maxima that correspond to metal and nonmetal oxides in the composition of the initial ash decreased to nearly zero. To remove graphite, the processed samples were annealed at 750 °C in air and studied. It was found that the applied approach made it possible to obtain a mixture of silicon carbide and aluminum nitride powders in direct current arc plasma initiated in ambient air, which reduced the energy consumption for ash processing by electric arc.

Микросферы из оксида иттрия для ядерной медицины

Cancers of liver are a problem of modern medicine. A common method of treatment is surgery. In patients who do not need surgery, various methods of local exposure can be prescribed (radiofrequency ablation, chemoembolization, brachytherapy, etc.). In the last decade, a method of treating cancer of liver — radioembolization of the liver-has been introduced into practice. The method is based on selective intra-arterial injection of glass or rubber microspheres containing yttrium radionuclide, resulting in local radiation exposure to tumor tissue. Recently, there has been increasing interest in the production of ceramic microspheres of the yttrium-90 (90Y) isotope. Narrow-fraction microspheres of pure yttrium oxide were obtained as a result of processing yttrium oxide powder in an air RF plasma. The resulting microspheres were subjected to ultrasonic treatment in deionized water, as a result of which the total specific surface area of the particles decreased by 10 %. Yttrium oxide microspheres were etched in a solution of sodium chloride for 11 days, after which the surface of the particles did not undergo significant changes. As a result, microspheres were obtained that have potential applications in nuclear medicine.

The Manufacture of GaN Powder in Plasma

In this paper, the preparation technology of GaN powder has been studied by using of plasma powder synthesis system, and several properties were improved such as: the morphology, the particle size, structure and optical properties. The result shows that, by applying for plasma method, high purity GaN powder was manufactured; the GaN has a good morphology and a regular spherical shape. The spherical ratio of the GaN powder was more than 95%; The GaN powder can be adjusted with different process parameters to achieve particle size control; The GaN powder has sharp diffraction peak and good crystallinity; The GaN powder has the structure of wurtzite and good luminescent properties.

Structural Changes in С36 Laves Phase Intermetallic Compound TiCr2 During Hydrogenation–Dehydrogenation Process

The paper deals with melting of titanium and chromium metal powders in plasma of abnormal glow discharge which results in the formation of the hexagonal С36 Laves phase compound TiCr2 with a = 4.928 A and c = 15.983 A lattice parameters. The hydrogenation–dehydrogenation process is used to prepare the powder of C36 Laves phase intermetallic compound TiCr. The hydrogenation–dehydrogenation process is performed at 100°C, 2 atm hydrogen pressure and 30 min ageing followed by vacuum cooling. The prepared metal powder is characterized by rounded lamellar and coarse particles 6 ± 2 μm and 21 ± 7 μm in size, respectively.

Set of Measures for Improving the Quality of Powders Based on Titanium for Additive Technology

The change in morphology of polygonal powder in a low-temperature plasma generated in an arc discharge is an effective means for resolving the problem of preparing titanium alloy powder of spherical shape used in additive technology. A method is studied for preparing spherical powder of titanium and its alloys by spheroidization in streams of a polygonal powder thermal plasma, prepared by hydrogenation-dehydrogenation. A production scheme is proposed for preparing spherical titanium alloy powder for additive technology, including remelting of certified waste, ingot hydrogenation, crushing, screening its fractions, dehydrogenation, and gas centrifugal classification with final plasma treatment. A technology is developed for preparing spherical titanium alloy powder used in additive technology, with a reduced dissolved gas content. Methods are considered for improving the quality of spheroidized titanium powder including: minimization of the amount of particles with size less than 10 μm in the original polygonal powder, a change in composition of the plasma-forming gas, and prevention of contact with air by powder before and after spheroidization.

Nitrogenation of hafnium carbide powders in AC and DC plasma by Electrical Discharge Assisted Mechanical Milling

Metal carbonitride powders and coatings are well known as superhard materials which are widely applied in many engineering products. Of this group of materials hafnium carbonitride properties are one of the least known due to difficulties with preparation. In this study, the electric discharge assisted mechanical milling (EDAMM) method involving a nitrogen plasma together with mechanical milling was used to synthetise hafnium carbonitride powders within minutes. It was found that difficulties in conventional manufacturing methods, resulting in the formation of only thin layers instead of bulk materials can be overcome by applying the new technique, and HfCxNy powder could be successfully engineered with controlled amount of nitrogen uptake.In this investigation we studied the effects of AC and DC discharges on nitrogen solubility in HfC powder. Microstructure and phase evolution were determined using XRD and SEM, while the nitrogen content in the grains was evaluated by EDS and bulk nitrogen content by CHN analysis. Maximum solubilities of 3.42 wt% and 2.95 wt%N under DC an AC discharge currents, respectively, were obtained. Reaction paths varied depending on processing conditions with HfCxNy formed under DC discharge processing and mixed products containing HfC, several HfCxNy phases and HfN like phase formed after AC processing. After nitrogenation the most highly nitrided powders were subjected to 1 min additional EDAMM processing using high power discharges to allow the formation of large, sintered particles of sufficient size to perform hardness measurements on. Vickers harnesses of fully sintered large particles after 5 and 10 min of EDAMM were 1808 and 2169HV, respectively.

Improvement of luminous efficiency using LI-doped MgO layer coated by MgCaO crystal powders in plasma display panels

ABSTRACTIn this study, the influences of the Li-doped MgO layer sprayed by MgCaO crystal powders on the discharge and luminous efficiency characteristics are examined under the high Xe (= 30%) gas condition in 6-in. test alternating-current plasma display panels (ac-PDPs) with 50-in. full-high definition (FHD) cell size. Our experimental results reveal that spraying the MgCaO crystal powders on the Li-500 ppm doped MgO layer can reduce the firing voltage considerably by about 60 V under the high Xe (= 30%) gas condition. As a result, the maximum luminous efficacy of about 40% improvement is obtained when adopting the Li-500 ppm doped MgO layer coated by MgCaO crystal powders under high Xe (= 30%) gas condition.

Synthesis of zinc oxide powders in plasma–solution systems

A new method is proposed for the synthesis of powdered zinc oxide with the use of a plasma–solution system. The chemical and phase compositions and the morphology of the synthesized powders have been determined. It has been found that the calcination of powders obtained in the plasma–solution system leads to the formation of ZnO.

Application of inductively coupled microplasma jet on rapid manufacturing

Metal rapid manufacture has received great attention in recent decades. Energy source with high power density is requisite for the metal deposition. Atmospheric pressure inductively coupled microplasma jet is commonly characterized by high temperatures, which is one of excellent candidates for metal rapid manufacture on a micro scale.In this paper, we investigate the microplasma jet driven by a 150 MHz very-high-frequency power supply at atmospheric pressure. A microplasma of 3 cm in length and about 3 mm in diameter can be produced at 90 W power applied, with gas temperatures above one thousand degree centigrade. The jet length rises first, and then decreases by increasing gas flow rate, showing a transition from laminar flow to turbulence. The jet length also increases by enhancing applied power, but then keeps a maximum value with further increasing power, which is attributed to the attainment of equilibrium between the energy absorption and losses in the transport process in plasma.Copper powders are carried by the argon flowing into plasma, and melted fast by the microjet. An alumina ceramic plate is used as a substrate, which is set on the substrate holder with a precisely controlled X-Y-Z manipulator. A copper spherical cap with 2 mm in diameter and a column with 1 cm in height are fabricated in a few seconds, respectively, on the alumina ceramic substrate. The Cu spherical cap is characterized by scanning electron microscopy. Particles obtained on the sample surface are far smaller than the source powders, indicating a melting process of copper powders in plasma, as well as high gas temperature exceeding the melting point of copper. The weak peak of Cu2+1O is present besides strong copper diffraction lines in X-ray diffraction pattern, suggesting that the weak oxidation happens during rapid fabrication.

Synthesis of oxidic powder in nonequilibrium low- temperature plasma with increase of indicators of quality of process

Ways of synthesis of powders in low-temperature plasma define various approaches in the solution of technological tasks for receiving difficult oxidic connections with various quality of a product. Research of model of electrothermal reactor installation with generation of low-temperature plasma is of special interest for synthesis of oxidic powder with the raised quality indicators. This approach defines technology of receiving details from powder materials of modern production.

The Manufacture of Spherical Titanium Alloy Powder in Plasma

In this study, the preparation technology of spherical titanium alloy powder (tc4) was studied by using continuous induction plasma powder synthesis system. The flow-ability, particle size and impurity content of the powder before and after plasma treatment were measured and compared. The result showed that, by applying induction plasma preparation technology, the powder's flow-ability was improved by 20% while oxygen and carbon content were decreased significantly. The powder's sphericization rate and recovery rate were above 95% and 90% respectively with plasma spherical treatment.

The Manufacture of Spherical WC Powder in Plasma

The manufacture technology of spherical WC powder has been studied by using of induction plasma. We can get spherical powder above 85% in the powder through changing several parameters. And the hall flow-ability, the oxygen content , particle size of powder before and after plasma treatment have been compared. The results were shown that oxygen contents was deduced markedly, and the plasma method can control the particle size easily.