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2001
Ferreira, Isabel, Rodrigo Martins, A. Cabrita, Hugo Águas, V. Silva, and Elvira Fortunato. "Silicon Films Produced by PECVD Under Powder Formation Conditions." Materials Science Forum. 382 (2001): 21-30. Abstract
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Martins, R., Águas Silva Ferreira Cabrita Fortunato H. V. I. "Silicon films produced by PECVD under powder formation conditions." Materials Science Forum. 382 (2001): 21-28. AbstractWebsite

The process conditions of growing thin silicon films by plasma enhanced chemical vapour deposition (PECVD) were presented. The plasma impedance was found to monitor the powders in the PECVD systems and good quality silicon films were grown close to the plasma regime where the powders were formed. The silicon films exhibited properties which were interpreted based on a two-phase model where silicon nanostructures were embedded in a disordered network.

Martins, Rodrigo, Hugo Águas, V. Silva, Isabel Ferreira, A. Cabrita, and Elvira Fortunato. "Silicon Films Produced by PECVD under Powder Formation Conditions." Materials Science Forum. Vol. 382. Trans Tech Publications, 2001. 21-30. Abstract
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Santos, J. P., P. Patté, F. Parente, and P. Indelicato. "Spontaneous relativistic two-photon decay rate mathematical expression in heliumlike systems." The European Physical Journal D. 13 (2001): 27-31. AbstractWebsite

We derive a theoretical expression for the two-photon emission rate of two-electron systems, in a form suitable for easy implementation in numerical calculations. Racah algebra techniques were used to extended previous work on two-photon emission in hydrogen-like systems to more complex ones. The obtained expression is, as far as we are aware, the first general expression that gives the spontaneous two-photon decay rates of helium-like systems for any combination of multipoles.

Gil, P., António Dourado, and J. Henriques. "State Space Neural Networks and the Unscented Kalman Filter in Online Nonlinear System Identification." IASTED, International Conference on Intelligent Systems and Control. n/a 2001. Abstract
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Henriques, J., António Dourado, and P. Gil. "State Space Neural Networks in Nonlinear Adaptive System Identification and Control." IFAC Workshop on Advanced Fuzzy/Neural Control 2001. n/a 2001. Abstract
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Alves, T., S. Besson, AS Pereira, G. W. Pettigrew, JJG Moura, and I. Moura. "Structure-function studies of cytochrome c peroxidase from ps. nautica." Journal of Inorganic Biochemistry. 86 (2001): 122. AbstractWebsite
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Franco, R., AS Pereira, P. Tavares, A. Mangravita, MJ Barber, I. Moura, and GC Ferreira. "Substitution of murine ferrochelatase glutamate-287 with glutamine or alanine leads to porphyrin substrate-bound variants." Biochemical Journal. 356 (2001): 217-222. AbstractWebsite

Ferrochelatase (EC 4.99.1.1) is the terminal enzyme of the haem biosynthetic pathway and catalyses iron chelation into the protoporphyrin IX ring. Glutamate-287 (E287) of murine mature ferrochelatase is a conserved residue in all known sequences of ferrochelatase, is present at the active site of the enzyme, as inferred from the Bacillus subtilis ferrochelatase three-dimensional structure, and is critical for enzyme activity. Substitution of E287 with either glutamine (Q) or alanine (A) yielded variants with lower enzymic activity than that of the wild-type ferrochelatase and with different absorption spectra from the wild-type enzyme. In contrast to the wild-type enzyme, the absorption spectra of the variants indicate that these enzymes, as purified, contain protoporphyrin IX. Identification and quantification of the porphyrin bound to the E287-directed variants indicate that approx. 80% of the total porphyrin corresponds to protoporphyrin IX. Significantly, rapid stopped-flow experiments of the E287A and E287Q Variants demonstrate that reaction with Zn2+ results in the formation of bound Zn-protoporphyrin IX, indicating that the endogenously bound protoporphyrin IX can be used as a substrate. Taken together, these findings suggest that the structural strain imposed by ferrochelatase on the porphyrin substrate as a critical step in the enzyme catalytic mechanism is also accomplished by the E287A and E287Q variants, but without the release of the product. Thus E287 in murine ferrochelatase appears to be critical For the catalytic process by controlling the release of the product.

Nunes, P., Fortunato Martins E. R. "Thin film combustible gas sensors based on zinc oxide." Materials Research Society Symposium - Proceedings. Vol. 666. 2001. F521-F526. Abstract

Sensitivity tests to reductive gases such as methane, hydrogen and ethane were performed on zinc oxide (ZnO) thin films. The highest value of sensitivity was obtained for the film with a high electrical resistivity and a low thickness. The variation of the operating temperature of the film leads to a significant change in the sensitivity of the sensor with an ideal operating temperature dependence of the gas used. The sensitivity of the ZnO thin films changes linear with the increase of the gas concentration. However these films seem to be more appropriated for the detection of hydrogen following by methane and than for ethane since the value of sensitivity obtained are higher and its variation with the gas concentration more pronounced.

Fortunato, Elvira, Patrícia Nunes, António Marques, Daniel Costa, Hugo Águas, Isabel Ferreira, Maria EV Costa, and Rodrigo Martins. "Thin Film Metal Oxide Semiconductors Deposited on Polymeric Substrates." MRS Proceedings. 685.1 (2001). Abstract
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Fortunato, E.a, Nunes Marques Costa Águas Ferreira Costa Martins P. a A. a. "Thin film metal oxide semiconductors deposited on polymeric substrates." Materials Research Society Symposium Proceedings. Vol. 685. 2001. 146-151. Abstract

Highly textured transparent conducting ZnO:Al thin films have been prepared by r.f. magnetron sputtering. The films were deposited on polyester (Mylar type D, 100 μm thickness) and glass substrates at room temperature. Surface stylus profiling, X-ray diffraction, scanning electron microscopy, transmission electron microscope and Hall effect measurements as a function of temperature, using the van der Pauw technique have characterized the films. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface (columnar structure). The ZnO:Al thin films with a resistivity as low as 3.6×10-2 Ωcm have been obtained, as deposited. © 2001 Materials Research Society.

Fortunato, E., Nunes Marques Costa Águas Ferreira Costa Martins P. A. D. "Thin film metal oxide semiconductors deposited on polymeric substrates." Materials Research Society Symposium - Proceedings. Vol. 666. 2001. F1131-F1136. Abstract

Highly textured transparent conducting ZnO:Al thin films have been prepared by r.f. magnetron sputtering. The films were deposited on polyester (Mylar type D, 100 μm thickness) and glass substrates at room temperature. Surface stylus profiling, X-ray diffraction, scanning electron microscopy, transmission electron microscope and Hall effect measurements as a function of temperature have been used to characterize the produced films. The samples are polycrystalline with a hexagonal wurtzke structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface (columnar structure). The ZnO:Al thin films with a resistivity as low 3.6×10-2 Ωcm have been obtained, as deposited.

Fortunato, Elvira, Patr{\'ıcia Nunes, António Marques, Daniel Costa, Hugo Águas, Isabel Ferreira, Maria EV Costa, and Rodrigo Martins. "Thin Film Metal Oxide Semiconductors Deposited on Polymeric Substrates." MRS Proceedings. Vol. 685. Cambridge University Press, 2001. D5-12. Abstract
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Cabrita, A., J. Figueiredo, L. Pereira, H. Aguas, V. Silva, D. Brida, I. Ferreira, E. Fortunato, and R. Martins. "Thin film position sensitive detectors based on pin amorphous silicon carbide structures." Applied surface science. 184.1 (2001): 443-447. Abstract
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Cabrita, A., Figueiredo Pereira Águas Silva Brida Ferreira Fortunato Martins J. L. H. "Thin film position sensitive detectors based on pin amorphous silicon carbide structures." Applied Surface Science. 184 (2001): 443-447. AbstractWebsite

The performances of silicon carbide position sensitive detectors in relation to position color selection applications were presented. The devices were deposited on glass substrates coated with a transparent conductive oxide layer based on indium tin oxide film (ITO). On top of the ITP layer a pin structure produced by plasma enhanced chemical vapor deposition technique was deposited. The set of data achieved indicated that the undoped silicon carbide layers presented a low density of states, which explained high dark conductivity values obtained and the type of performances recorded on the PSD devices produced.

Cabrita, A., J. Figueiredo, L. Pereira, H. Aguas, V. Silva, D. Brida, I. Ferreira, E. Fortunato, and R. Martins. "Thin film position sensitive detectors based on pin amorphous silicon carbide structures." Applied surface science. 184 (2001): 443-447. Abstract
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Martins, R., H. Águas, I. Ferreira, E. Fortunato, and L. Guimarães. "Towards the improvement of the stability of a-Si: H pin devices." Solar energy. 69 (2001): 257-262. Abstract
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Martins, R., H. Aguas, I. Ferreira, E. Fortunato, and L. Guimaraes. "Towards the improvement of the stability of a-Si: H pin devices." Solar energy. 69 (2001): 257-262. Abstract
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Fortunato, Elvira, Patrícia Nunes, António Marques, Daniel Costa, Hugo Águas, Isabel Ferreira, Maria EV Costa, and Rodrigo Martins. "Zinc oxide thin films deposited by rf magnetron sputtering on mylar substrates at room temperature." MRS Proceedings. 685 (2001). Abstract
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Fortunato, E.a, Nunes Marques Costa Águas Ferreira Costa Martins P. a A. a. "Zinc oxide thin films deposited by rf magnetron sputtering on mylar substrates at room temperature." Materials Research Society Symposium Proceedings. Vol. 685. 2001. 140-145. Abstract

Aluminium doped zinc oxide thin films (ZnO:Al) have been deposited on polyester (Mylar type D, 100 μm thickness) substrates at room temperature by r.f. magnetron sputtering. The structural, morphological, optical and electrical properties of the deposited films have been studied. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. The ZnO:Al thin films with 85% transmittance in the visible and infra-red region and a resistivity as low as 3.6×102 Ωcm have been obtained, as deposited. The obtained results are comparable to those ones obtained on glass substrates, opening a new field of low cost, light weight, small volume, flexible and unbreakable large area optoelectronic devices. © 2001 Materials Research Society.

Fortunato, Elvira, Patr{\'ıcia Nunes, António Marques, Daniel Costa, Hugo Águas, Isabel Ferreira, Maria EV Costa, and Rodrigo Martins. "Zinc oxide thin films deposited by rf magnetron sputtering on mylar substrates at room temperature." MRS Proceedings. Vol. 685. Cambridge University Press, 2001. D5-10. Abstract
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Cabrito, I., AS Pereira, P. Tavares, S. Besson, C. Brondino, B. Hoffman, K. Brown, M. Tegoni, C. Cambillau, JJG Moura, and I. Moura. "{Nitrous oxide reductase (N2OR) from Pseudomonas nautica 617}." Journal Of Inorganic Biochemistry. 86 (2001): 165.
Carrapa, R. T., O. M. N. Teodoro, and A. M. C. Moutinho. "{Positive and negative ion emission from perfluorinated}." Chemical Physics Letters. 336 (2001): 431-438. Abstract

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Cabrita, A., L. Pereira, D. Brida, A. Lopes, A. Marques, I. Ferreira, E. Fortunato, and R. Martins. "{Silicon carbide photodiodes: Schottky and PINIP structures}." Applied Surface Science. 184 (2001): 437-442. AbstractWebsite
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