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Abstract: Mullite and mullite-zirconia composites were prepared in twin step through low power transferred arc plasma (TAP) torch melting followed by mechanical mixing. The mixture was based on 3:2 mole ratios of alumina and silica; alumina and zircon were ball milled and melted for 3min in a transferred arc plasma torch at 3 kW input power with 10 lpm of argon flow rate. The phase and microstructure formation of the melted samples was investigated by XRD and SEM respectively. The crystalline behavior of the mullite and mullite–zirconia composite was evaluated by differential thermal analysis. The obtained results clearly showed that the complete mullization was achieved only in alumina–silica system and partial mullization occurred in alumina–zircon system due to the inadequate plasma torch input power. [Copyright &y& Elsevier]

Abstract: Natural bovine hydroxyapatite/SiO2–CaO–MgO glass–ceramics were produced using the transferred arc plasma (TAP) processing method. Homogeneous mixtures of HA/25wt% SiO2–CaO–MgO and HA/50wt% SiO2–CaO–MgO batches obtained by dry mixing the respective compositions in a ball mill were processed in argon plasma using the TAP torch at 5kW for 1, 2 and 3min, respectively. The synthesized glass–ceramic samples were studied for phase composition, microstructure and bioactivity. The phase study of the synthesized glass–ceramics revealed the formation of calcium phosphate silicate with traces of calcium silicate. The structural study by SEM revealed that the prepared samples possessed smooth glassy surface morphology. The in vitro-bioactivity of the TAP synthesized glass–ceramics was examined in simulated body fluid (SBF). The SBF test results confirmed the development of crystalline carbonated apatite phase after 12 days of immersion. The cytocompatibility was evaluated through human fibroblast cell proliferation. The fibroblasts culture results showed that the sample was non-toxic and promoted cell growth. [Copyright &y& Elsevier]

Abstract: Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. Critical plasma spraying parameter (CPSP) is a key factor to control the quality of coatings. In this study, Alumina–Titania composite coatings in different compositions (Alumina–3wt.% Titania, Alumina–13wt.% Titania and Alumina–40wt.% Titania) were prepared by 40kW atmospheric plasma spray torch at three different CPSP conditions (833.33, 1000 and 1166.66) and their influence on coatings and plasma jet temperature were studied. The phase, microstructure, sliding and erosive wear rates, microhardness and porosity of the different Alumina–Titania composite coatings was investigated and correlated to CPSP conditions. The result shows that increasing CPSP increases the hardness and anti wear behavior of Alumina–Titania composite coatings except Alumina–40wt% Titania coating. [Copyright &y& Elsevier]

Abstract: The excitation temperature and electron number density of the atmospheric pressure D.C. argon plasma jet during spheroidization of nickel have been measured at 5mm from the nozzle exit by optical emission spectroscopic technique. Emission spectra of the argon plasma, argon plasma with carrier gas and carrier gas with nickel powder were recorded in 400–450nm wavelength interval. The effect of carrier gas and powder loading on the excitation temperature and electron number density of the plasma jet were determined using atomic Boltzmann plot method and stark broadening of the Ar I (430.010nm) line respectively. The experiment was done at 6.5, 7.9, 11.4 and 12.1kW input power levels. Argon was used as plasma gas and also carrier gas. Nickel powders in the size ranging from 40 to 100μm were processed. On introduction of carrier gas and nickel powder loading, the excitation temperature and electron density of the jet were found to decrease. From the results, the degree of ionization of the plasma jet was calculated by using the measured excitation temperature and electron density values. The spheroidzed nickel powder was characterized by SEM, optical photographs and XRD. [Copyright &y& Elsevier]

Abstract: Low cost mullite–zirconia composites were prepared from the mixtures of natural bauxite and zircon sand by using transferred arc plasma processing. In this paper, a mixture of natural bauxite and zircon in the ratio of 7:3 by weight (based on composition of 3:2 mullite) was ball milled for 4h and melted in the transferred arc plasma for 2 and 4min. Argon was used as plasma forming gas. The torch was operated at 5kW input power. The phase and microstructure formation of melted samples were investigated by XRD and SEM images. The results show that the processing time is a key factor to get a single phase mullite–zirconia composites with required microstructure. [Copyright &y& Elsevier]

Abstract: In this study, the adhesive properties of the plasma modified polypropylene (PP) and polyethylene terephthalate (PET) film surfaces have been investigated. Hydrophilicity of these polymer film surfaces was studied by contact angle measurements. The surface energy of the polymer films was calculated from contact angle data using Fowkes method. The chemical composition of the polymer films was analyzed by X-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) was used to study the changes in surface feature of the polymer surfaces due to plasma treatment. The adhesion strength of the plasma modified film was studied by T-peel strength test. The results showed a considerable improvement in surface wettability even for short exposure times. The AFM and XPS analyses showed changes in surface topography and formation of polar groups on the plasma modified PP and PET surfaces. These changes enhanced the adhesive properties of polymer film surfaces. [Copyright &y& Elsevier]

Abstract: In the present work, hydroxyapatite (Ca10(PO4)6(OH)2) was prepared from bovine bones with calcination method (up to 850°C).The calcinated hydroxyapatite was powdered (30–40μm) using a mechanical grinder; the particles were highly irregular in shape with sharp edges, angular, rounded, circular, dentric, porous and fragmented morphologies. The irregular shaped calcinated hydroxyapatite was plasma processed to produce spherical powders for thermal spray coating applications. More over; calcium phosphate silicate glass ceramics was produced by plasma melting of ball milled hydroxyapatite–borosilicate glass (50wt.%) mixture. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and energy dispersive X-ray analysis (EDX). The morphology was determined using scanning electron (SEM) and optical microscopy (OM). The microhardness, density and porosity measurements for the synthesized samples were made. [Copyright &y& Elsevier]

Abstract: In this paper, the results of plasma spheroidization of iron powders using a DC non-transferred plasma spray torch are presented. The morphology of the processed powders was characterized through scanning electron microscopy (SEM) and optical microscopy (OM). The percentages of spheroidized powders were calculated by the shape factors such as the Irregularity Parameter (IP) and Roundness (RN). A maximum of 83% of spheroidization can be achieved. The spheroidization results are compared with the theoretical estimation and they are found to be in good agreement. The phase composition of the spheroidized powder was analyzed by XRD. The effect of plasma jet temperature and plasma gas flow rate on spheroidization is discussed. At low plasma gas flow rates and at high plasma jet temperatures, the percentage of spheroidization is high. [Copyright &y& Elsevier]

Abstract: Using a non-transferred DC plasma spray torch, nanosized alumina particles were synthesized from micron-sized aluminium particles. Irregular-shaped micron-sized alumina particles were spheroidized using the plasma spray torch. The synthesized powder particles were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, Fourier transform infra-red (FT-IR) spectroscopy and photoluminescence (PL) spectroscopy. The synthesized alumina nanoparticles appear spherical in shape, but mostly agglomerated in the size range 30–75nm. It was identified that the main phase is γ-alumina with a small amount of δ-alumina. In the spheroidized alumina particles, the main phase is α-alumina with a small amount of γ-alumina. The mechanism of formation of alumina and its phase change are explained in detail. [Copyright &y& Elsevier]

Abstract: Intermetallic iron aluminide alloy nanoparticles were synthesized by non-transferred DC plasma spray torch at atmospheric pressure. These powder particles were characterized by vibrating sample magnetometer (VSM), X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), laser scattering particle size distribution analyzer, energy dispersive X-ray spectra (EDX) and thermo gravimetric-differential thermal analysis (TG/DTA) studies and the results are discussed. Commercially available iron and aluminium powders in the size range between 40 and 100μm were ball milled with suitable ratio (Fe-85% and Al-15%) by weight to form a iron–aluminium blende; this was used as feed stock to synthesize iron aluminide nanoparticles. These nanoparticles particles were spherical in shape and black in colour, with the size range between 30 and 70nm observed by ESEM. It is seen that the powders processed at higher power levels (15.3kW) have more number of single spherical nanoparticles than powders processed at lower power levels (9.8kW). The formation of iron aluminide nanoparticles is confirmed by XRD analysis and an exothermic reaction by DTA studies. [Copyright &y& Elsevier]

Abstract: In this paper, aluminium macro powders in the size range between 300 and 500μm are processed by thermal plasma processing. A 40kW DC non-transferred DC plasma spray torch was used to get the macro powders. The morphology and the size of the powders are discussed and the results are reported. The powders produced are doughnut shaped. The size ranges between 300 and 500μm. The macro particle size is estimated theoretically and found to be in good agreement with experimental results. The error percentage between theoretical estimation and experimental result is about 25%. The pressure inside the particle is estimated. The pressure gradient develops the indentation on the powder surface which seems to be doughnut. [Copyright &y& Elsevier]

Expansion of T cells is a crucial step of many cellular immunotherapy protocols, which require large numbers of immune cells to eradicate malignant cells. However, it remains a major translational and commercial bottleneck due to the manual, small scale culturing systems used for their production. One of the main concerns is that primary T cells are shear sensitive and therefore do not grow as effectively in more scalable, agitated systems, such as stirred tank bioreactors, as compared with static conditions. However, the use of stirred culture systems for T cell expansion offers many potential advantages over the static culture systems commonly used today, including homogeneity of culture conditions, ease of sampling, and implementation of control systems. In our study, we explore a robust and practical platform for adoptive cell culture using stirred-tank bioreactor and novel biaxial rotary bioreactor for large-scale and high-quality cellular production. We have investigated various factors, such as bioreactor parameters, media, supplements and stimulation, with a suitable structure of scaling-up the bioreactors with robustness and reproducibility of the process. T cell quality was monitored using surface markers and intracellular cytokines as the critical quality assessment criteria in early, middle and late stages of cell production. Our approach addresses the fundamental scaling challenges in the manufacturing process. [ABSTRACT FROM AUTHOR]

Abstract: In thermal plasma processing, input power and gas flow rate play a major role in controlling the plasma jet temperature, velocity and density. Emission spectroscopy study is an important method for plasma diagnostics. A DC atmospheric plasma spray torch was operated at different power levels and flow rates of plasma gas (argon). Electron number density of the plasma jet, the corresponding temperature and the degree of ionization were determined using stark broadening of the Ar I (430.010nm) line, the atomic Boltzmann plot method and the Saha equation, respectively. In the present work, we have investigated the effect of input power, axial position of the plasma jet and gas flow rate on the electron number density in the plasma jet. While an increase in input power considerably increased the electron number density, gas flow rate did not show any significant effect on the same. [Copyright &y& Elsevier]