Design of hierarchical porous aluminas by using one-pot synthesis and different calcination temperatures

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Transient non-Darcy forced convective heat transfer from a flat plate embedded in a fluid-saturated porous medium

Transient non-Darcy forced convection on a flat plate embedded in a porous medium is investigated using the Forchheimer-extended Darcy law. A sudden uniform pressure gradient is applied along the flat plate, and at the same time, its wall temperature is suddenly raised to a high temperature. Both the momentum and energy equations are solved by retaining the unsteady terms. An exact velocity solution is obtained and substituted into the energy equation, which then is solved by means of a quasi-similarity transformation. The temperature field can be divided into the one-dimensional transient (downstream) region and the quasi-steady-state (upstream) region. Thus the transient local heat transfer coefficient can be described by connecting the quasi-steady-state solution and the one-dimensional transient solution. The non-Darcy porous inertia works to decrease the velocity level and the time required for reaching the steady-state velocity level. The porous-medium inertia delays covering of the plate by the steady-state thermal boundary layer. © 1990.

Approximate solution for non-Darcy transient film condensation in a porous medium

The problem of non-darcian transient film condensation adjacent to a vertical flat plate embedded in a porous medium has been considered. The governing equation for the boundary layer thickness was obtained by an integral method and solved approximately by the method of integral relations. It is shown that the results are in good agreement with those obtained exactly by the method of characteristics.

Powder processing and In Vivo evaluation of a titanium porous coating implant

The processing of titanium porous coatings using powder metallurgy technique to achieve a porous structure that allows osseointegration with bone tissue was discussed. The porous microstructure exhibited micropores and interconnected macropores with size ranges that allowed bone ingrowth. The macropores in the coatings were originated from the binder evaporation while the micropore was related with the porous titanium powder and the low compaction pressure used. The in vivo evaluation indicated that osseointegration had occurred between the bone and porous material.

Construction of a chamber for in situ monitoring of the drying process of gels and porous solids

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

Porous silica matrix obtained from pyrex class by hydrothermal treatment: Characterization and nature of the porosity

A novel porous silica matrix has been prepared from Pyrex glass, using hydrothermal treatment under saturated-steam condition. This process makes it possible to obtain, in one step, a silica support formed of a homogeneously distributed and interconnected macropore microstructure. The new matrix contains silanol groups that can be used in reactions of surface modification to provide a hybrid material and a selective macrofiltration membrane, and also it can improve chemical inertness. The porous matrix is noncrystalline as obtained and, after thermal treatment at temperatures higher than 950degreesC, exhibits an X-ray pattern characteristic of alpha-cristobalite and low volume contraction. The present samples were characterized by scanning electron microscopy, mercury intrusion porosimetry, nitrogen adsorption-desorption isotherms, infrared spectroscopy, X-ray powder diffractometry, atomic absorption, and high-resolution solid-state nuclear magnetic resonance. The results present a new way of producing a macroporous silica matrix.

Construção de uma câmara para monitoramento in situ do processo de secagem de geis e sólidos porosos

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

SAXS measurements of the porosity in Cu(II)-doped SnO2 xerogels during crystallization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

β-galactosidase immobilization on controlled pore silica

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

Microstructural characteristics and electrochemical behavior of Co3O4 sintered electrodes

Co3O4 can be used as electrocatalyst for oxygen evolution reaction. The macro and microstructure of the oxide, obtained by compacting and sintering lithium-doped Co3O4 powder in atmosphere of dry air and in conditions of controlled temperature and time was analyzed by metallographic techniques. The porous material was characterized by XRD, SEM and EDS combined techniques. For working temperatures up to 1200°C, the pellet was consituted of particles with varying sizes over a wide range of particle size and, at higher temperatures CoO is formed and polymorphic transformation was observed. The materials were also characterized electrochemically in alkaline media by open circuit potential and potentiodynamic I/E measurements. The results were compared to those previously prepared by others by thermal deposition.

Stagnant effective thermal conductivity of agro-industrial residues for solid-state fermentation

The stagnant effective thermal conductivities (K0) of sugar cane bagasse (SCB), wheat bran (WB), orange pulp and peel (OPP) and their combination (weight proportion 1:2:2 SCB/OPP/WB) were obtained using the line heat source method. These solid materials were applied to pectinase production via solid-state fermentation. The moisture content ranged from 4 to 80% (w.b.). A conduction mechanism through the porous media was observed, along with conduction through a liquid film and contact thermal resistance between the samples and the probe. K0 was low for intermediate moisture contents and approached the molecular conductivity of water for high moisture contents. © 2013 Copyright Taylor and Francis Group, LLC.

Níquel (II) e moléculas orgânicas multidentadas como building blocks na construção de sólidos de coordenação porosos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento de estruturas porosas de polietileno de ultra alto peso molecular (PEUAPM) recobertas com apatitas para substituição e regeneração óssea

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aluminas macro-mesoporosas produzidas pelo método sol-gel para aplicação em catálise heterogênea

Pós-graduação em Química - IQ