53 research outputs found
TiO2/PDMS nanocomposites for use on self-cleaning surfaces
AbstractIn this study, polydimethylsiloxane (PDMS)/TiO2 nanocomposite was processed by the spray method. TiO2 nanoparticles were synthesized by microwave-assisted hydrothermal method. Varying the proportion of nanoparticles in 0%, 0.5% and 1% by weight, commercial TiO2 (P25) was used for comparison purposes. The photocatalytic activity of nanocomposites impregnated with methylene blue was assessed by means of UVâvisible spectroscopy. Changes in contact angle were analyzed before and after UV degradation tests. The effect of ultraviolet radiation on the chemical structure of the PDMS matrix was evaluated by Fourier transform infrared spectroscopy (FTIR). The results indicated that the addition of TiO2 nanoparticles in PDMS provides good photocatalytic properties in the decomposition of methylene blue, which is an important characteristic for the development of coatings for self-cleaning. For comparison purposes, commercial P25 was also used to investigate the photocatalytic activity
Thermal performance of a solar hybrid dryer for Conilon coffee (Coffea canephora)
The study was aimed at design and development of an energy efficient hybrid solar
dryer suitable for drying of organic Conilon coffee placed in the town of Seropédica, Rio de
Janeiro, Brazil. The energy efficiency and the drying efficiency were the evaluation criteria for
thermal performance of the hybrid solar dryer during the coffee drying. Temperature and relative
humidity (RH) of the drying and ambient air, solar radiation intensity and coffee weight loss were
monitored during the drying process. The process occurred over six consecutive days; the drying
time was from 07:00 to 17:00 h, totalling 120 h of operation with an intermittent period (at night)
of 14 h. During intermittence, the exhaust system kept off and solar collector and drying chamber
sealed. The effective drying period took 60 h, with temperature and RH, respectively, of 38.3 °C
and 60.6% outlet of the solar collector, 32.7 °C and 72.2% outlet drying chamber and 27.8 °C
and 74.5% ambient air. The maximum temperature in the solar collector and drying chamber
reached 54 and 47.7 °C, respectively, with an ambient air temperature of 32 °C at 12:00 h. These
values showing temperature increase 22.2 °C in solar collector and 10 ÂșC drying chamber. The
mean variation for the reduction in RH between the drying air inside the solar collector and the
ambient air was 28%, while in the chamber obtained in a range of 10.5% at 13:00 h. The solar
collector and dryer chamber efficiency were 29.1 and 40.8%, respectively, while the overall dryer
efficiency 39.7%
Efeito da adição do resĂduo de rocha ornamental nas propriedades e microestrutura de porcelana elĂ©trica aluminosa
Efeitos de hormĂŽnios esteroides de contraceptivos orais combinados sobre os parĂąmetros comportamentais de Betta splendens (Regan, 1909)
Association of loss of heterozygosity with cytogenetic abnormalities in acute myeloid leukemia and myelodysplastic syndrome
Vigor de sementes de coentro (Coriandrum sativum L.) provenientes de sistemas orgĂąnico e convencional
Argentina, Brasil e Venezuela: as diferentes percepçÔes sobre a construção do Mercosul
Composição quĂmica e aminoacĂdica e coeficientes de digestibilidade verdadeira dos aminoĂĄcidos de farinhas de penas e sangue determinados em galos cecectomizados
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