Explore the vast range of titles available.

In the deposition of polymer-like carbon (PLC) films on Si substrates via radio-frequency plasma CVD (RF-PCVD), the effect of the Ar/CH4 gas mixture ratio on the bio-interface of the PLC films remains unclear and the effectiveness of introducing Ar gas must be proven. In this study, five types of PLC films are prepared on Si substrates via RF-PCVD with an Ar/CH4 gas mixture. The effects of the Ar/CH4 gas ratio on the structure, surface properties, and osteoblast proliferation of the PLC films are investigated. The PLC film structure is graphitized as the hydrogen content in the PLC film decreases with the increasing Ar gas ratio. Based on in vitro cell culture tests, a PLC film with a higher Ar gas ratio promotes the osteoblast proliferative potential after 72 h compared with a PLC film with a relatively low Ar gas ratio. Moreover, the surface roughness and hydrophilicity of the PLC film increase with the Ar gas ratio. Accordingly, we demonstrate the effectiveness of Ar gas incorporation into the RF-PCVD process to promote the biological responsiveness of PLC films. PLC coatings are expected to be widely applied for surface modification to improve the mechanical characteristics and biological responses of orthopedic implant devices.

The Radio-Frequency Plasma Thruster (RFPT), relying on an electromagnetic coupling mechanism for plasma excitation and energy regulation, offers advantages such as high ionization efficiency, long operational lifetime, wide controllability, and strong system reliability, making it a key development direction in micro-propulsion technology. Experimental studies have shown that wall losses are the critical factor limiting its performance improvement. To reduce wall dissipation and enhance ionization efficiency, this work introduces permanent magnets into the thruster structure, applying an axial static magnetic field to effectively suppress radial plasma diffusion. A multi-physics coupled model was established on the COMSOL Multiphysics ® platform, incorporating plasma, electromagnetic field, laminar flow, and heat transfer modules, to systematically investigate the ionization enhancement mechanism under magnetic confinement. Simulation results demonstrate that, at an input power of 100 W, the electron density increases by approximately 23.8 times compared with the case without magnetic fields; within the power range of 50–1000 W, the electron density exhibits a good linear growth, with a maximum increase of up to 13.7 times. These results confirm the significant regulatory role of static magnetic fields on plasma behavior and provide theoretical support for the design of high-performance RF plasma thrusters.

The suitability of alumina powder produced through radio frequency (RF) plasma spheroidization for ceramic 3D printing feedstock is investigated. The fundamental and essential physical and microstructural characteristics of alumina powders for 3D printing are presented in this study. Powder-based ceramic 3D printing requires specific properties, including particle morphology, purity, mechanical, chemical, and thermal attributes. RF plasma spheroidization is an advanced method for producing powders with desired properties on a commercial scale compared to traditional techniques. This technique involves heating and melting irregular alumina bulk particles using RF plasma and then cooling them rapidly to form spherical powders. The spheroidization process results in α-Al 2 O 3 formation and a corundum structure. Particle morphology, structural characteristics, and purity of alumina powder were analyzed using various spectroscopy and microscopy methods, such as electron microscopy, x-ray diffraction, energy dispersive x-ray spectroscopy, and glow discharge mass spectroscopy techniques. Findings showed nearly spherical particles, with diameters ranging from a few to 200 μm and an average size of 84.5 ± 25.2 μm, high crystallization, and 99% purity. These particles have a distinctive surface texture and cellular structure, along with open surface voids. This study also highlights the capabilities and limitations of the RF plasma spheroidization technique.

In this study, a radio-frequency plasma-assisted chemical beam epitaxy (RF-PACBE) system with low growing temperatures was used to grow high-quality indium nitride (InN) thin films. The prepared InN thin films were annealed through a line-shaped CO 2 laser beam irradiation in an atmospheric environment at room temperature. The structural and electrical properties of InN thin films annealed with different CO 2 laser annealing parameters were measured and analyzed. The crystalline grains turned into large and granular morphologies after the InN thin films were annealed under various feeding speeds of a motorized X -axis positioning stage. According to the measured XRD patterns and rocking curves, the InN (0 0 2) peak intensities of laser-annealed thin films were higher than those of as-grown InN thin films. All surface roughnesses and sheet resistances of laser-annealed InN thin films were higher and less than those of as-grown InN thin films. At the set feeding speed of 7.5 mm/s, the laser-annealed InN thin film had the largest grain size of 69.4 nm and the lowest sheet resistance of 20.21 ± 0.27 Ω/sq. The experimental results revealed that the proper annealing conditions could decrease grain boundaries and release internal stresses to enhance the electrical properties through adjusting feeding speeds.

Titanium for additive manufacturing presents a challenge in the control of costs in the fabrication of products with expanding applications compared with cast titanium. In this study, hydrogenated–dehydrogenated (HDH) titanium powder with a low cost was employed to produce spherical Ti powder using the radiofrequency plasma (RF) technique. The spherical Ti powder was used as the raw material for laser directed energy deposition (LDED) to produce commercially pure titanium (CP-Ti). Microstructural analyses of the powder revealed that RF treatment, not only optimized the shape of the titanium powder, but also benefited in the removal of the residual hydride phase of the powder. Furthermore, the LDED-HDH-RF-produced samples showed an excellent combination of tensile strength and tensile ductility compared to the cast and the LDED-HDH-produced samples. Such an enhancement in the mechanical properties was attributed to the refinement of the α grain size and the dense microstructure. The present work provides an approach for LDED-produced CP-Ti to address the economic and mechanical properties of the materials, while also providing insights into the expanding application of HDH titanium powder.

The optical emission spectroscopy technique is used to determine the vibrational temperature of the second positive band system, N 2 ( C , υ ′ - B , υ ″ ) in the wavelength range 367.1–380.5 nm by using the line-ratio and Boltzmann plot methods. The electron temperature is evaluated from the intensity ratio of the selected molecular bands corresponding to N 2 + ( B , υ - X , υ ′ , 391.44 nm), and, N 2 ( C , υ ′ - B , υ ″ , 375.4 nm) transitions, respectively. The selected bands have a different threshold of excitation energies and thus serve as a sensitive indicator of the electron energy distribution function (EEDF). The electron density has been determined from the intensity ratio of the molecular transitions corresponding to N 2 + ( B , υ - X , υ ′ , 391.44 nm), and, N 2 ( C , υ ′ - B , υ ″ , 380.5 nm) for different levels of pressure and radio frequency power. The results show that the vibrational temperature decreases with increasing nitrogen fill pressure and radio frequency power. However, the electron temperature increases with radio frequency power and reduces with fill pressure. The electron density increases both with nitrogen fill pressure and radio frequency power that attributes to the effective collisional transfer of energy producing electron impact ionization. Plasma parameters show a significant dependence on discharge conditions and can be fine-tuned for specific surface treatments. Article Highlights Spectrum analysis of RF-driven nitrogen plasma for varying discharge conditions Evaluation of vibrational temperature using line-ratio and Boltzmann plot methods Comparison of vibrational temperatures for line-ratio and Boltzmann plot methods Evaluation of electron temperature and density using the intensity-ratio of bands Correlation of temperature and density with varying fill pressure and RF power

The aim of this study was to investigate how morphology of fibers is affected by plasma during the process of decolorization by a low-pressure RF plasma (gas, treatment time, and power were varied) and atmospheric pressure industrial corona (number of passages and power). CIE LAB colorimetric system was used for determination of color difference between untreated and differently plasma-treated denim fabrics. Particular emphasis was put on the morphological changes induced by plasma treatment, because they indicate changes in mechanical properties of the fabrics. The morphology of plasma-treated fibers was analyzed by scanning electron microscopy (SEM). SEM images revealed that, when plasma conditions that lead to a decolorization were chosen, specific fiber surface changes were always observed in the form of submicrometer-sized striations, pits, and cracks. Mechanical properties of denim fabrics were moderately influenced by treatment conditions. The results indicated that decolorization was highly affected by plasma parameters and desired `worn look' effects could be designed by adequate control of plasma processing while paying attention to limiting the plasma-induced damage.

Searches for transient astrophysical sources often reveal unexpected classes of objects that are useful physical laboratories. In a recent survey for pulsars and fast transients, we have uncovered four millisecond-duration radio transients all more than 40° from the Galactic plane. The bursts' properties indicate that they are of celestial rather than terrestrial origin. Host galaxy and intergalactic medium models suggest that they have cosmological redshifts of 0.5 to 1 and distances of up to 3 gigaparsecs. No temporally coincident x-or gamma-ray signature was identified in association with the bursts. Characterization of the source population and identification of host galaxies offers an opportunity to determine the baryonic content of the universe.

The substitution of petroleum-based polymers with naturally derived biopolymers may be a good alternative for the conservation of natural fossil resources and the alleviation of pollution and waste disposal problems. However, in order to be used in a wide range of applications, some biopolymers’ properties should be enhanced. In this study, biocompatible, non-toxic, and biodegradable chitosan (CS) film and CS reinforced with 10 wt% of cellulose nanocrystals (CN–CS) were coated with amorphous hydrogenated carbon layers (a–C:H) of different thickness. To investigate the effect of the nano-reinforcement on the a–C:H layer applied, mild radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) was used to coat the CS and its CN–CS bio-nanocomposite film. Both the surface characteristics and the chemical composition were analyzed. The surface morphology and wettability were examined by ex-situ atomic force microscopy (AFM) and contact angle measurements (CA), respectively. Hereby, the relationship between sp2/sp3 ratios on a macroscopic scale was also evaluated. For the investigation of the chemical composition, the surface sensitive synchrotron X-ray radiation techniques near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) as well as diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) were used.

Developing rapid and diverse microbial mutation tool is of importance to strain modification. In this review, a new mutagenesis method for microbial mutation breeding using the radio-frequency atmospheric-pressure glow discharge (RF APGD) plasma jets is summarized. Based on the experimental study, the helium RF APGD plasma jet has been found to be able to change the DNA sequences significantly, indicating that the RF APGD plasma jet would be a powerful tool for the microbial mutagenesis with its outstanding features, such as the low and controllable gas temperatures, abundant chemically reactive species, rapid mutation, high operation flexibility, etc. Then, with the RF APGD plasma generator as the core component, a mutation machine named as atmospheric and room temperature plasma (ARTP) mutation system has been developed and successfully employed for the mutation breeding of more than 40 kinds of microorganisms including bacteria, fungi, and microalgae. Finally, the prospect of the ARTP mutagenesis is discussed.