ResumenSe obtuvieron estructuras porosas de TiO2-Na0.8Ti4O8-Na2Ti6O13 mezclando, compactando y sinterizando TiO2 con bicarbonato de sodio como agente porogénico (15% y 30% en peso de NaHCO3). Las muestras se compactaron y trataron a 1100 °C durante 4 h y 8 h. Se analizaron los efectos del tiempo de sinterización y el porcentaje en peso de NaHCO3 sobre las propiedades mecánicas superficiales, porosidad y citotoxicidad. Los patrones de difracción de rayos X se refinaron por el método Rietveld, usando GSAS. Las microestructuras se observaron mediante microscopía electrónica de barrido y el efecto de composición de los materiales sobre la respuesta celular in vitro se evaluó usando ensayo LDH de citotoxicidad. La porosidad varió entre 3.2% y 11.9%, la microdureza superficial entre 251.4 HV0.2 y 851.6 HV0.2. Los resultados de citotoxicidad en la línea celular CHO (ovario de Hámster chino) muestran que las estructuras porosas no son citotóxicas y tienen potencial para su aplicación en ingeniería de tejidos ortopédicos.
AbstractPorous structures TiO2-Na0.8Ti4O8-Na2Ti6O13 were obtained by mixing, compacting and sintering TiO2 with sodium bicarbonate as porogenic agent (15 and 30 wt.% of NaHCO3). The samples were compacted and treated at 1100 °C for 4 h and 8 h. The effects of sintering time and the weight percent of NaHCO3 on surface mechanical properties, porosity and cytotoxicity were analyzed. The X-ray diffraction patterns were refined by the Rietveld method. Microstructures were observed by scanning electron microscopy and the effect of material composition on the cellular response in vitro was evaluated using a LDH-cytotoxicity assay. The porosity varied between 3.2% and 11.9%, the surface microhardness between 251.4 HV0.2 and 851.6 HV0.2. The cytotoxicity results on the CHO cell line (Chinese Hamster ovary) show that the porous structures are not cytotoxic and has potential for orthopedic tissue engineering applications.
This paper presents preliminary results on the design, construction and evaluation of a passive mini direct ethanol fuel cell (DEFC), capillary fed with 2 mol l-1 aqueous ethanol, at a rate of 2.03 μL min-1, and air oxygen in the cathode through an air vent. Parameters such as pressure, temperature and time of manufacturing a membrane-electrode assembly (MEA) by hot-pressure were evaluated. As the electrode holder used a 0.25 cm2 carbon tissue which was deposited on the catalytic layer (C. L.) for both the anode (0.8 mg cm-2of PtRu/C) and the cathode (0.8 mg cm -2of Pt/C), Nafi on® 115 membranes were used as the electrolyte. The results show, an average power density of 302 μWcm2 under the best conditions used, a catalytic layer with a Nafi on percentage of 50% at 25 °C. A temperature of 125 °C, a pressure of 49.2 Kg/cm2, and 90 seconds duration were used to obtain the MEA.
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