Alendouro, M.S.J.G.a, Monteiro Figueiredo Martins Silva Ferro Fernandas R. C. C. a. "
Microstructural characterization and properties of a glass and a glassceramic made from municipal incinerator bottom ash."
Materials Science Forum. 455-456 (2004): 827-830.
AbstractA glass was made using bottom ash produced by a Portuguese municipal solid waste (MSW) incinerator. The bottom ash was the single batch material used in the formation of the glass, which was obtained through a conventional melt-quenching method. The glass was then converted to glass-ceramic for further recycling to construction materials. After submitting the glass samples to several heat treatments, between 820 and 1050°C and during different times, it was verified that the optimum heat treatment schedule for the ceramization of the glass was at 1000°C for 10h, as confirmed by microstructural observation and by X-ray diffraction. The major crystalline phases precipitated in the glass-ceramic were wollastonite (CaSiO3) and diopside (Ca(Mg,Al)(Si,Al)2O6). Microstructural analysis of the glass-ceramic revealed that the crystalline phases were present as dendrites and fiber-like structures that were homogeneously distributed in the material. The glassceramic showed good mechanical properties with a hardness of 5.6 MPa and a bending strength of 101 MPa. This material had a density of 2.8 gcm-3 and a thermal expansion coefficient of 9.10-6°C-1. The glass and the glass-ceramic showed an excellent chemical stability against leaching in acidic solution and in alkaline solution. In summary, both the glass and the glass-ceramic have good chemical and mechanical properties and can, therefore, be applied as construction materials.
Alendouro, M. S. J. G. a, R. C. C. a Monteiro, C. F. M. L. a Figueiredo, R. M. S. a Martins, R. J. C. a Silva, M. C. b Ferro, and M. H. V. b Fernandas. "
Microstructural characterization and properties of a glass and a glassceramic made from municipal incinerator bottom ash."
Materials Science Forum. 455-456 (2004): 827-830.
AbstractA glass was made using bottom ash produced by a Portuguese municipal solid waste (MSW) incinerator. The bottom ash was the single batch material used in the formation of the glass, which was obtained through a conventional melt-quenching method. The glass was then converted to glass-ceramic for further recycling to construction materials. After submitting the glass samples to several heat treatments, between 820 and 1050°C and during different times, it was verified that the optimum heat treatment schedule for the ceramization of the glass was at 1000°C for 10h, as confirmed by microstructural observation and by X-ray diffraction. The major crystalline phases precipitated in the glass-ceramic were wollastonite (CaSiO3) and diopside (Ca(Mg,Al)(Si,Al)2O6). Microstructural analysis of the glass-ceramic revealed that the crystalline phases were present as dendrites and fiber-like structures that were homogeneously distributed in the material. The glassceramic showed good mechanical properties with a hardness of 5.6 MPa and a bending strength of 101 MPa. This material had a density of 2.8 gcm-3 and a thermal expansion coefficient of 9.10-6°C-1. The glass and the glass-ceramic showed an excellent chemical stability against leaching in acidic solution and in alkaline solution. In summary, both the glass and the glass-ceramic have good chemical and mechanical properties and can, therefore, be applied as construction materials.
Fortunato, E., P. Barquinha, A. Pimentel, A. Goncalves, L. Pereira, A. Marques, and R. Martins. "
Next generation of thin film transistors based on zinc oxide."
Integration of Advanced Micro-and Nanoelectronic Devices-Critical Issues and Solutions. Eds. J. Morais, D. Kumar, M. Houssa, R. K. Singh, D. Landheer, R. Ramesh, R. M. Wallace, S. Guha, and H. Koinuma. Vol. 811. Materials Research Society Symposium Proceedings, 811. 2004. 347-352.
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Fortunato, E., Barquinha Pimentel Gonçalves Pereira Marques Martins P. A. A. "
Next generation of thin film transistors based on zinc oxide."
Materials Research Society Symposium Proceedings. Vol. 811. 2004. 347-352.
AbstractWe report high performance ZnO thin film transistor (ZnO-TFT) fabricated by rf magnetron sputtering at room temperature with a bottom gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 19 V, a field effect mobility of 28 cm2/Vs, a gate voltage swing of 1.39 V/decade and an on/off ratio of 3×105. The ZnO-TFT present an average optical transmission (including the glass substrate) of 80% in the visible part of the spectrum. The combination of transparency, high field-effect mobility and room temperature processing makes the ZnO-TFT a very promising low cost optoelectronic device for the next generation of invisible and flexible electronics.
Pauleta, Sr., F. Guerlesquin, C. F. Goodhew, B. Devreese, J. VanBeeumen, AS Pereira, I. Moura, and G. W. Pettigrew. "
Paracoccus pantotrophus pseudoazurin is an electron donor to cytochrome c peroxidase."
Biochemistry. 43 (2004): 11214-11225.
AbstractThe gene for pseudoazurin was isolated from Paracoccus pantotrophus LMD 52.44 and expressed in a heterologous system with a yield of 54.3 mg of pure protein per liter of culture. The gene and protein were shown to be identical to those from P. pantotrophus LMD 82.5. The extinction coefficient of the protein was re-evaluated and was found to be 3.00 mM(-1) cm(-1) at 590 nm. It was confirmed that the oxidized protein is in a weak monomer/dimer equilibrium that is ionic- strength-dependent. The pseudoazurin was shown to be a highly active electron donor to cytochrome c peroxidase, and activity showed an ionic strength dependence consistent with an electrostatic interaction. The pseudoazurin has a very large dipole moment, the vector of which is positioned at the putative electron-transfer site, His81, and is conserved in this position across a wide range of blue copper proteins. Binding of the peroxidase to pseudoazurin causes perturbation of a set of NMR resonances associated with residues on the His81 face, including a ring of lysine residues. These lysines are associated with acidic residues just back from the rim, the resonances of which are also affected by binding to the peroxidase. We propose that these acidic residues moderate the electrostatic influence of the lysines and so ensure that specific charge interactions do not form across the interface with the peroxidase.
Pereira, L., Águas Martins Fortunato Martins H. R. M. "
Polycrystalline silicon obtained by gold metal induced crystallization."
Journal of Non-Crystalline Solids. 338-340 (2004): 178-182.
AbstractThe aim of this paper is to study the role of gold (Au) induced crystallization on amorphous silicon (a-Si) films produced by low pressure chemical vapor deposition (LPCVD) at low process temperatures (550 °C) to allow the use of glass substrates. Concerning the crystallization process Au was deposited by e-beam thermal evaporation over the silicon (Si), using different metal thickness, from 5 to 100 Å. The samples were then annealed at 450, 500 and 550 °C and the crystallization time was changed from 5 up to 30 h. The structure of the films was analyzed by X-ray diffraction (XRD) and spectroscopic ellipsometry (SE) while electrical conductivity measurements were performed to obtain the electrical properties of the films produced, namely the activation energy (EA) and how it changes with the Au thickness used. The data achieved show that the increase of the metal layer thickness decreases the time needed to get full crystallization. However this leads to lower conduction activation energy (EA) meaning that there is also an increase of Au incorporation that leads to the production of doped films. © 2004 Elsevier B.V. All rights reserved.
Pereira, L.a, Águas Martins Vilarinho Fortunato Martins H. a R. M. "
Polycrystalline silicon obtained by metal induced crystallization using different metals."
Thin Solid Films. 451-452 (2004): 334-339.
AbstractThe aim of this paper is to study the role of different metals (aluminium, molybdenum, nickel and titanium) in inducing crystallization in films produced by LPCVD at high and low temperature processes and to compare the structural, morphological, optical and electrical properties of the various films produced. This work envisages the use of the most suitable conditions that lead to the production of films for optoelectronic applications such as solar cells. © 2003 Elsevier B.V. All rights reserved.