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Abstract: Hydroxyapatite (Ca10(PO4)6(OH)2, abbreviated as HA) is a kind of bioactive material that has received considerable attention over the past decades as an implant material due to its excellent biocompatability for clinical applications. In this work, Hydroxyapatite was obtained by plasma processing of the natural bovine bones by Transferred arc plasma (TAP) processing at 5 kW in argon plasma for different processing times (i.e. 30, 45, 60, 90 and 120 s). The TAP synthesized HA bioceramic was characterized by XRD, FTIR, SEM-EDX and TG-DTA analysis. The effect of TAP processing time on the preparation of organic free HA from bovine bone was studied. The study indicated that TAP processing for 30, 45 and 60 s were insufficient for removal of organics from the natural bovine bone. Organic free bovine HA was obtained for 90 s TAP processing with a Ca/P ratio of 1.93 comparable with commercially available natural HA-Endobon powder. Whereas 120 s of processing resulted in trivial thermal decomposition of HA in to its constituent phases. Thus our present investigation suggested that HA production from bovine bone using TAP processing is a time effective advantageous method in comparison to the annealing method. [Copyright &y& Elsevier]

Arc plasma melting technique is a simple method for the synthesis of high melting point materials. In this article, mullite was synthesized by transferred arc plasma (TAP) and nontransferred arc plasma (non-TAP) melting processes, and the results were compared. The mixes of alumina and silica powders (3:2 mole ratios) were ball milled for four hours and then melted in an arc plasma torch, used in transferred and nontransferred mode, at 5 kW input power and two minutes of processing time. Argon gas was used as a plasma-forming gas. The crystalline phases and the microstructural features of the melted samples were determined by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. A complete crystallization of mullite, with dense, thick whiskers-shaped crystals, was achieved in TAP processing of the alumina/silica system. On the other hand, the non-TAP process produced porous mullite along with a small amount of residual alumina phase. Differential thermal analysis (DTA) curves of the synthesized mullite samples allowed a deeper understanding of the mechanisms of mullite formation during the two different processes. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the surfaces of PET/TiO2 thin film were modified by DC glow discharge plasma as a function of discharge potentials for improving the bioactivity. The hydrophilicity of the plasma-treated PET/TiO2 film was measured by contact angle measurement and the surface energy was estimated by using Fowkes method. The structural and chemical composition of the plasma-treated PET/TiO2 was analysed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Immersion in a simulated body solution (SBF) solution was used to evaluate the bioactivity of the plasma-treated PET/TiO2 samples in vitro. It was found that the plasma treatment modified the surfaces both in chemical composition and crystallinity which makes surface of the PET/TiO2 to become more hydrophilic compared with untreated one. Analytical and microstructural investigations of SBF results, showed considerable higher rates of apatite formation on the plasma-treated PET/TiO2 compared to the untreated films. [Copyright &y& Elsevier]

Abstract: Nanocrystalline titanium oxide powder has been synthesized by reactive plasma processing. The precursor powder of TiH2 is oxidized ‘in-flight’ in a thermal plasma reactor to generate nanocrystalline titania powder. The synthesized powder consists of nano-sized particles of anatase and rutile phases of titanium dioxide. Photocatalytic activity of the plasma-synthesized powder was evaluated by studying the degradation of methylene blue dye solution under direct sunlight as well as UV irradiation. FTIR spectroscopy and X-ray photoelectron spectroscopy have been used to analyze the catalytic activity of the plasma-synthesized powder. UV–visible diffused reflectance spectra of the plasma-synthesized TiO2 samples showed that they absorb in the visible region leading to effective photocatalytic activity in sunlight. The results corroborated that the plasma-synthesized powder can be effectively used for outdoor applications. [Copyright &y& Elsevier]

Abstract: In this paper, synthesis of CaO–MgO–SiO2 glass ceramic using transferred arc plasma (TAP) processing method is illustrated. Homogeneous mixture of 51.6% SiO2, 35.6% CaO and 12.8% MgO prepared by dry mixing in a ball mill was kept in the anode well (which is the melting bed) of the 10kW transferred arc plasma torch. It was melted in plasma at an operating power of 5kW (by varying the processing time for 3, 5 and 8min). The melt was cooled to solidify by applying forced air on it. The resulting samples were characterized for microstructure and phase composition. The phases were identified by scanning electron microscopy (SEM), using the back-scattered electron (BSE) image mode and X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The microstructure was examined using optical microscopy (OM) and scanning electron microscopy. The micro-hardness, density and porosity measurements for the synthesized samples were carried out. Differential thermal analysis (DTA) was performed to study the thermal evolution. The results show the formation of diopside phase in the transferred arc plasma melted CaO–MgO–SiO2 glass ceramic system achieved with in a quite considerable short time of plasma processing. The method indicated that TAP technique could be a promising, time saving and one-step manufacturing process for the production of functional bulk glass ceramics. [Copyright &y& Elsevier]

Abstract: Polyethylene terephthalate (PET) films were treated with DC glow discharge plasma followed by graft copolymerization with acrylic acid (AA) and polyethylene glycol (PEG). The obtained PET–PEG was coupled to heparin or insulin molecules. The surfaces were then characterized by contact angle measurements, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The surface energies of the modified PET films were estimated using contact angle measurements, and the changes in crystallinity of the plasma-modified PET film surfaces were investigated by X-ray diffraction (XRD) analysis. The blood compatibilities of the surface-modified PETs were examined by in vitro thrombus formation, whole blood clotting time, platelet contact and protein adsorption experiments. The results revealed that the contact angle value decreased and that the interfacial tension between the modified PET films and blood protein was drastically diminished compared to unmodified PET film. The XPS results showed that the PET–AA surface containing carboxylic acid and the immobilized PET surface containing both carboxylic acid and amino groups exhibited a hydrophilic character, and AFM results showed marked morphological changes after grafting of AA, PEG and biomolecule immobilization. Heparin and insulin-coupled PET surfaces exhibited much less platelet adhesion and protein adsorption than the other surface-modified PET film surfaces. [Copyright &y& Elsevier]

Abstract: In this paper the hydrophilic improvement of the grey cotton fabric by low pressure dc glow discharge air plasma is investigated. The fabrics were treated for different exposure times, discharge potentials and pressure levels. Effect of plasma treatment on the wettability of the fabric was studied by measuring contact angle and dynamic wicking rate. The surface energy values have been estimated using contact angle measurements and effective mean pore radius of the plasma-treated fabrics were estimated by modified Washburn equation via dynamic wicking technique. Degradation and dyeability of the fabrics were determined by weight loss percentage and computer colour matching procedure. Characterization of the functional changes due to the plasma treatment has been carried out by means of Fourier transform infrared spectroscopy (FTIR–ATR). The surface morphology of the untreated and plasma-treated fabrics were analyzed by scanning electron microscopy (SEM). [Copyright &y& Elsevier]

Abstract: A DC non-transferred mode plasma spray torch was fabricated for plasma spheroidization. The effect of powder-carrier gas and powder loading on the temperature of the plasma jet generated by the torch has been studied. The experiment was done at different input power levels; the temperature of the jet was within 5000–7000K argon was used as plasma gas and powder-carrier gas. Nickel powder particles in the size range from 40 to 100μm were processed. The temperature of the jet was estimated after flowing powder-carrier gas only into the plasma jet and with powder-carrier gas feeding powder into the flame. On introduction of powder-carrier gas and powder loading the temperature of the jet was found to decrease appreciably down to 11%. The temperature of the plasma jet was estimated using the Atomic Boltzmann plot method. [Copyright &y& Elsevier]

Analyzes the trajectories of a nonrelativistic single charged particle in a nonadiabatic cusped magnetic field configuration. Depth of penetration of the particle into the cusped field; Multiple reflections and radial excursion of the particle transmitted by the cusped field.