Reactive synthesis of Ti-Al intermetallics during microwave heating in an E-field maximum

The time-resolved X-ray diffraction synchrotron radiation technique was used in combination with E-field microwave heating to study in situ the kinetics of intermetallic phase formation in the Ti-Al system. The reaction of Ti with Al is triggered by the melting and spreading of Al onto the surface of Ti particles. The tetragonal TiAl 3 phase is the primary reaction product, formed by instantaneous nucleation at the interface between the unreacted Ti cores and the Al melt. The growth of TiAl 3 layers is diffusion-controlled. These preliminary results demonstrate that microwave heating can be used to rapidly synthesise intermetallic phases from high-purity elemental powders. © 2010 Elsevier B.V. All rights reserved.This work has been supported by the Swiss National Science Foundation (Grant 20PA21E-129193).Vaucher, S.; Stir, M.; Ishizaki, K.; Catalá Civera, JM.; Nicula, R. (2011). Reactive synthesis of Ti-Al intermetallics during microwave heating in an E-field maximum. Thermochimica Acta. 522(1):151-154. doi:10.1016/j.tca.2010.11.026S151154522

Enhanced laser thermal ablation for the in vitro treatment of liver cancer by specific delivery of multiwalled carbon nanotubes functionalized with human serum albumin

The main goal of this investigation was to develop and test a new method of treatment for human hepatocellular carcinoma (HCC). We present a method of carbon nanotube-enhanced laser thermal ablation of HepG2 cells (human hepatocellular liver carcinoma cell line) based on a simple multiwalled carbon nanotube (MWCNT) carrier system, such as human serum albumin (HSA), and demonstrate its selective therapeutic efficacy compared with normal hepatocyte cells. Both HepG2 cells and hepatocytes were treated with HSA–MWCNTs at various concentrations and at various incubation times and further irradiated using a 2 W, 808 nm laser beam. Transmission electron, phase contrast, and confocal microscopy combined with immunochemical staining were used to demonstrate the selective internalization of HSA–MWCNTs via Gp60 receptors and the caveolin-mediated endocytosis inside HepG2 cells. The postirradiation apoptotic rate of HepG2 cells treated with HSA–MWCNTs ranged from 88.24% (for 50 mg/L) at 60 sec to 92.34% (for 50 mg/L) at 30 min. Significantly lower necrotic rates were obtained when human hepatocytes were treated with HSA–MWCNTs in a similar manner. Our results clearly show that HSA–MWCNTs selectively attach on the albondin (aka Gp60) receptor located on the HepG2 membrane, followed by an uptake through a caveolin-dependent endocytosis process. These unique results may represent a major step in liver cancer treatment using nanolocalized thermal ablation by laser heating

Two-Functional Direct Current Sputtered Silver-Containing Titanium Dioxide Thin Films

The article reports on structure, mechanical, optical, photocatalytic and biocidal properties of Ti–Ag–O films. The Ti–Ag–O films were reactively sputter-deposited from a composed Ti/Ag target at different partial pressures of oxygen on unheated glass substrate held on floating potentialUfl. It was found that addition of ~2 at.% of Ag into TiO2film has no negative influence on UV-induced hydrophilicity of TiO2film. Thick (~1,500 nm) TiO2/Ag films containing (200) anatase phase exhibit the best hydrophilicity with water droplet contact angle (WDCA) lower than 10° after UV irradiation for 20 min. Thick (~1,500 nm) TiO2/Ag films exhibited a better UV-induced hydrophilicity compared to that of thinner (~700 nm) TiO2/Ag films. Further it was found that hydrophilic TiO2/Ag films exhibit a strong biocidal effect under both the visible light and the UV irradiation with 100% killing efficiency ofEscherichia coliATCC 10536 after UV irradiation for 20 min. Reported results show that single layer of TiO2with Ag distributed in its whole volume exhibits, after UV irradiation, simultaneously two functions: (1) excellent hydrophilicity with WDCA < 10° and (2) strong power to killE. colieven under visible light due to direct toxicity of Ag

Káderpolitikai tevékenység a tanácsok vb. hivatali szervezetében

INST: L_08

Effect of welding parameters on mechanical and microstructural properties of AL 2024 joints produced by friction stir welding

Results of Friction Stir Welding (FSW) of aluminium 2024 are presented in this paper. Investigations were conducted on the welding machine, built on the base of the conventional, vertical milling machine. The quality assessment of joints was done on the grounds of the visual inspection, tensile and fatigue tests, the analysis of the welds structure and hardness. Heat treatment was not done after the welding process. The goal of the research was to know the relationship between welding parameters and mechanical and microstructural properties of 2024joints. Results indicate that weldability of aluminium alloys of Al 2024 4 mm in thickness with FSW method is good. Properties ofjoints with the FSW method on the milling machine eąuipped with LOWSTIR device fulfil requirements of this kind of joints. The structure is correct and the tensile properties are higher than properties of arc welded joints. With wide range of welding parameters the high quality of joint is possible. Joints welded with the different tools and in different conditions had characteristic shape of nugget, heat affected zone and thermo-mechanically affected zone. The kind of tool is not affected on properties of FSW joint at the same parameters. The proper quality at four different kind of tool is possible to achieve. Fatigue properties of the FSW joints made in correct way are very high, higher than properties of arc welded joints. Hardness profile of welds had characteristic run, typical for joints welded with the FSW method. The LOWSTIR device is not getting worse the quality of FSW joints

Synthesis of bone-like micro-porous calcium phosphate/iota-carrageenan composites by gel diffusion

Brushite and octacalcium phosphate (OCP) crystals are well-known precursors of hydroxylapatite (HAp), the main mineral found in bone. In this report, we present a new method for biomimicking brushite and OCP using single and double diffusion techniques. Brushite and OCP crystals were grown in an iota-carrageenan gel. The aggregates were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and thermal gravimetric analysis (TGA). SEM revealed different morphologies of brushite crystals from highly porous aggregates to plate-shaped forms. OCP crystals grown in iota-carrageenan showed a porous spherical shape different from brushite growth forms. The XRD method demonstrated that the single-diffusion method favors the formation of monoclinic brushite. In contrast, the double diffusion method was found to promote the formation of the triclinic octacalcium phosphate OCP phase. By combining the different parameters for crystal growth in carrageenan, such as ion concentration, gel pH and gel density, it is possible to modify the morphology of composite crystals, change the phase of calcium phosphate and modulate the amount of carrageenan inclusion in crystals. This study suggests that iota-carrageenan is a high-molecular-weight polysaccharide that is potentially applicable for controlling calcium phosphate crystallization

Spark plasma sintering synthesis of porous nanocrystalline titanium alloys for biomedical applications

The reason for the extended use of titanium and its alloys as implant biomaterials stems from their lower elastic modulus, their superior biocompatibility and improved corrosion resistance compared to the more conventional stainless steel and cobalt-based alloys [Niinomi, M., Hattori, T., Niwa, S., 2004. Material characteristics and biocompatibility of low rigidity titanium alloys for biomedical applications. In: Jaszemski, M.J., Trantolo, D.J., Lewandrowski, K.U., Hasirci, V., Altobelli, D.E., Wise, D.L. (Eds.), Biomaterials in Orthopedics. Marcel Dekker Inc., New York, pp. 41-62]. Nanostructured titanium-based biomaterials with tailored porosity are important for cell-adhesion, viability, differentiation and growth. Newer technologies like foaming or low-density core processing were recently used for the surface modification of titanium alloy implant bodies to stimulate bone in-growth and improve osseointegration and cell-adhesion, which in turn play a key role in the acceptance of the implants. We here report preliminary results concerning the synthesis of mesoporous titanium alloy bodies by spark plasma sintering. Nanocrystalline cp Ti, Ti-6Al-4V, Ti-Al-V-Cr and Ti-Mn-V-Cr-Al alloy powders were prepared by high-energy wet-milling and sintered to either full-density (cp Ti, Ti-Al-V) or uniform porous (Ti-Al-V-Cr, Ti-Mn-V-Cr-Al) bulk specimens by field-assisted spark plasma sintering (FAST/SPS). Cellular interactions with the porous titanium alloy surfaces were tested with osteoblast-like human MG-63 cells. Cell morphology was investigated by scanning electron microscopy (SEM). The SEM analysis results were correlated with the alloy chemistry and the topographic features of the surface, namely porosity and roughness