Colour change of soft denture liners after storage in coffee and coke

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sewage sludge coke estimation using thermal analysis

The imposition of more stringent legislation by CETESB in the State of So Paulo (Brazil) governing the disposal and utilization of sewage sludge, coupled with the growth in its generation has prompted a drive for alternative uses of sewage sludge. One option that is especially promising, due to its potential to valorize sludge, is its conversion into carbonaceous adsorbents or coke for industrial effluents treatment. Thus, a methodology is presented to estimate the coke produced from the sludge of a sewage treatment station using thermal analysis. The used sewage sludge, which comes from aerobic treatment, was collected in the wastewater treatment station of Barueri, one of the largest of the So Paulo metropolitan area. The sludge samples were collected, dried, ground, and milled until they passed an ABNT 200 sieve. The inert ambient used during its thermal treatment produces inorganic matter and coke as residual materials. Coke formation occurs in the 200-500 A degrees C range and, between 500 and 900 A degrees C, its thermal decomposition occurs. The highest formation of coke occurs at 500 A degrees C.

Composite resin color stability: influence of light sources and immersion media

Objective: This study evaluated the influence of light sources and immersion media on the color stability of a nanofilled composite resin. Material and Methods: Conventional halogen, high-power-density halogen and high-power-density light-emitting diode (LED) units were used. There were 4 immersion media: coffee, tea, Coke (R) and artificial saliva. A total of 180 specimens (10 mm x 2 mm) were prepared, immersed in artificial saliva for 24 h at 37 +/- 1 degrees C, and had their initial color measured with a spectrophotometer according to the CIELab system. Then, the specimens were immersed in the 4 media during 60 days. Data from the color change and luminosity were collected and subjected to statistical analysis by the Kruskall-Wallis test (p<0.05). For immersion time, the data were subjected to two-way ANOVA test and Fisher's test (p<0.05). Results: High-power-density LED (Delta E=1.91) promoted similar color stability of the composite resin to that of the tested halogen curing units (Jet Lite 4000 plus - Delta E=2.05; XL 3000 - Delta E=2.28). Coffee (Delta E=8.40; Delta L=-5.21) showed the highest influence on color stability of the studied composite resin. Conclusion: There was no significant difference in color stability regardless of the light sources, and coffee was the immersion medium that promoted the highest color changes on the tested composite resin.

Síntese do anodo cerâmico La1-xSr xCr0,5Mn0,5O3 pela técnica dos precursores poliméricos

Compostos da família La1-xSr xCr0,5Mn0,5O3 são apontados como potenciais anodos cerâmicos de células a combustível de óxidos sólidos. A utilização de anodos cerâmicos tem como objetivo eliminar os problemas de depósito de carbono na superfície do níquel e a baixa resistência a ciclos de redução/oxidação observados no compósito cerâmica-metal à base de zircônia estabilizada e níquel, que é o material anódico mais usado nestas células. Neste estudo são apresentados os resultados da síntese pela técnica dos precursores poliméricos e da caracterização de compostos com x = 0,5, estequiométrico e com 5% de deficiência catiônica no sítio A da estrutura perovskita La1-xSr xCr0,5Mn0,5O3 e (La1-xSr x)0,95Cr0,5Mn0,5O3, respectivamente. Os resultados evidenciam que o composto estudado possui altos valores de condutividade elétrica e baixa reatividade com eletrólitos à base de zircônia.

Cogasification of solid fuels

High efficiency gas turbine based systems, utility deregulation and more stringent environmental regulations strongly favor the use of natural gas over coal and other solid fuels in new electricity generators. Solid fuels could continue to compete, however, if a low cost gasifier fed by low cost feedstocks can be coupled with a gas turbine system. We examine on-site gasification of coal with other domestic fuels in an indirectly heated gasifier as a strategy to lower the costs of solid fuel systems. The systematics of gaseous pyrolysis yields assembled with the help of thermal measurement data and molecular models suggests blending carbonaceous fuels such as coal, coke or char with oxygenated fuels such as biomass, RDF, MSW, or dried sewage sludge. Such solid fuel blending can, with the help of inexpensive catalysts, achieve an optimum balance of volatiles, heating values and residual char thus reducing the technical demands upon the gasifier. Such simplifications should lower capital and operating costs of the gasifier to the mutual benefit of both solid fuel communities.

Utilização do coque verde de petróleo da Petrobras em substituição parcial ao carvão mineral das misturas injetadas em altos fornos

The Petrobras produced green petroleum coke (GPC) is a carbon rich fuel, virtually ash-free, with low sulfur content, and is a fuel suitable to replace metallurgical coke in blast furnaces. The GPC was tested in a pulverized coal injection simulator built in the Volta Redonda research center. It presented a low burning efficiency due to low volatile material content and high substitution rate by the carbon content. The tests were carried out in blast furnaces with ≤ 50% Petrobras GPC in the coal blends. The injected coal/CVP mixtures produced no negative side effects in the blast furnace grinding systems, pneumatic conveying, or operating process. The mixture burning process inside the blast furnace showed a decrease in fuel consumption, with a significant reduction in metallurgical coke consumption. The industrial-scale tests of the GPC mixtures did not reach the 70% maximum for lack of the GPC feedstock, which is necessary to continue with standard coal mixtures.

Estudo da combustão de carvões e misturas com o coque verde de petróleo injetadas em altos fornos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Utilização de syngas em substituição a combustíveis gasoso em processos siderúrgicos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da fonte de luz na estabilidade de cor de resina composta. Efeito dos meios e tempos de imersão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da utilização de biomassa em substituição parcial ao carvão mineral utilizado no processo de fabricação do ferro gusa em alto-forno

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise do escoamento turbulento por um queimador industrial a gás utilizando dinâmica dos fluidos computacional

Pós-graduação em Engenharia Mecânica - FEG

Numerical modeling of flow through an industrial burner orifice

This paper presents numerical modeling of a turbulent natural gas flow through a non-premixed industrial burner of a slab reheating furnace. The furnace is equipped with diffusion side swirl burners capable of utilizing natural gas or coke oven gas alternatively through the same nozzles. The study is focused on one of the burners of the preheating zone. Computational Fluid Dynamics simulation has been used to predict the burner orifice turbulent flow. Flow rate and pressure at burner upstream were validated by experimental measurements. The outcomes of the numerical modeling are analyzed for the different turbulence models in terms of pressure drop, velocity profiles, and orifice discharge coefficient. The standard, RNG, and Realizable k-epsilon models and Reynolds Stress Model (RSM) have been used. The main purpose of the numerical investigation is to determine the turbulence model that more consistently reproduces the experimental results of the flow through an industrial non-premixed burner orifice. The comparisons between simulations indicate that all the models tested satisfactorily and represent the experimental conditions. However, the Realizable k-epsilon model seems to be the most appropriate turbulence model, since it provides results that are quite similar to the RSM and RNG k-epsilon models, requiring only slightly more computational power than the standard k-epsilon model. (C) 2014 Elsevier Ltd. All rights reserved.

Substituição isomórfica de íons gálio em zeólitas de estrutura mfi para modificação da acidez do catalisador e controle da desativação na desidratação do glicerol

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Uma análise da tradução de vocábulos relacionados à violência e criminalidade presentes em três obras de Patrícia Melo

Pós-graduação em Estudos Linguísticos - IBILCE

SnO2 dense ceramic microwave sintered with low resistivity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)