Mário Ferreira - Academia.edu (original) (raw)

Papers by Mário Ferreira

Portugaliae Electrochimica Acta

ABSTRACT

Portugaliae Electrochimica Acta

ABSTRACT

Progress in Organic Coatings

... same concentration of chromate, zinc yellow has a high inhibitive power compared to other sim... more ... same concentration of chromate, zinc yellow has a high inhibitive power compared to other simple chromate ... applied to hot-dip galvanised steel (HDG) by dipping the substrates into the paint for 1 ... samples for the SVET study was chosen in order to allow a closer approach of the ...

Potentiometry with ion-selective microelectrodes measures activity of specific cations and anions... more Potentiometry with ion-selective microelectrodes measures activity of specific cations and anions at the solid/liquid interface from the solution side. Anodic and cathodic components of corrosion processes change local concentration of H+, OH-, metal cations and ions of the supporting electrolyte. These changes can be detected and quantified by SIET, making this technique an alternative, or complement, to methods based on potential and current changes across the interface. This mini-review describes SIET basics and demonstrates several examples of SIET applications relevant to corrosion studies.

Inhibitor-enriched protective coatings are able to tolerate mechanical impact followed by corrosi... more Inhibitor-enriched protective coatings are able to tolerate mechanical impact followed by corrosion attack. This is achieved via chemical interaction of corrosion inhibiting species with magnesium surface and formation of compact corrosion products that prevent further corrosion propagation and restore the main coating functionality: corrosion protection. Three main functional components contribute to success of a self-healing coating: durable polymer matrix, inhibitor repository and efficient corrosion inhibitor. This work describes our approach to composite protective coatings for WE43 magnesium alloy disclosing the details of all three main protective components. The combination of newly identified corrosion inhibitors for magnesium alloys was used to impart self-healing ability to fault-tolerant coatings. The results of electrochemical tests presented below demonstrate that developed composite coating provided enhanced long-term corrosion protection for the magnesium alloy, both...

The application fields of cerium compounds have enlarged in the last years. Cerium oxide is emerg... more The application fields of cerium compounds have enlarged in the last years. Cerium oxide is emerging as a hydrocarbon catalyst in self cleaning ovens and is now extensively used as a promoter in three- way catalysts (TWCs) for automotive emission control (1). This oxide allows for selective absorption of ultraviolet light in glass and, owing to its nonstoichiometric behaviour once the oxidation state of Ce can be 3+ or 4+, CeO2 also proved to be a good promoter for oxygen storage (2). The cerium oxide is also used in diesel fuels for a more complete combustion to abate soot formation (3). Moreover the magneto-optical signals of Ce-compounds have an outstanding figure of merit amongst other classes of magnetic materials (4). Synchrotron radiation is nowadays a powerful means of studying X-ray absorption fine-structure spectroscopy (XAFS), either close to the absorption edge (XANES) or up to a hundred electron volts above the edge (EXAFS). The latter has revealed itself as an outstand...

This paper presents an introduction to the SVET (Scanning Vibrating Electrode Technique). It star... more This paper presents an introduction to the SVET (Scanning Vibrating Electrode Technique). It starts with a brief historical account, followed by the operating principle, examples of application to corrosion, possible calculations, limitations, instrumentation, technical details and examples of its association with other electrochemical techniques.

Progress in Organic Coatings, 2015

ABSTRACT In this work we review results obtained using chitosan as a coating to protect aluminum ... more ABSTRACT In this work we review results obtained using chitosan as a coating to protect aluminum alloy 2024. Different inhibitors were added to the matrix, interaction between inhibitor and functional groups from chitosan investigated and functionalization of chitosan performed in the bulk, as well as at the coating/solution interface to improve the barrier properties. The obtained systems were characterized by proton-nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The protective performance was monitored using electrochemical impedance spectroscopy (EIS) and the scanning vibrating electrode technique (SVET). Overall, the obtained results support the possibility of using inhibitor-loaded chitosan systems to protect metallic substrates, either as components in multi-layer coatings systems, or as free-standing films.

Electrochimica Acta, 2015

ABSTRACT The direct use of high-ordered porous templates of anodic aluminium oxide for formation ... more ABSTRACT The direct use of high-ordered porous templates of anodic aluminium oxide for formation of nanostructures via electrochemical deposition is difficult because the presence of the of barrier alumina layer in the bottom of pores. In this paper, zinc electrodeposition from a solution of ZnCl2 in a choline chloride / ethylene glycol eutectic mixture on dense alumina layers of different thicknesses was studied. In a potentiostatic regime, the deposition on a barrier layer was found to be hardly possible even when the layer is a native alumina film (about 2 nm thick). Choline and ethylene glycol form an adsorbed stable layer at the alumina/electrolyte interface and thereby block the access of zinc chloride anions to the electrode.

ABSTRACT The study of areas of sympatry of species with predominantly parapatric distributions ma... more ABSTRACT The study of areas of sympatry of species with predominantly parapatric distributions may provide valuable insights about the factors shaping species occurrence. This information is key in biogeography, evolutionary biology and conservation planning. In this study we model the distributions of two pairs of partially co-occurring amphibian species in the Iberian Peninsula: tree frogs (Hyla molleri and H. meridionalis), with 11% of the occupied area shared by both species; and midwife toads (Alytes obstetricans and A. cisternasii), which co-occur in 4% of the total occupied area. We obtained distribution data from the herpetological atlases of Portugal and Spain, consisting of presences and absences on UTM 10x10-km grid cells. We built generalized linear models of presence / absence for each species and for the co-occurrence of each species pair, using 24 potential predictor variables representative of Iberian physiography, climate and human activity. Variables were selected for each model using information and significance criteria. The models were rated using calibration and discrimination measures and were compared using non-parametric correlation analysis after accounting for spatial autocorrelation. Preliminary results show a negative correlation between environmental favourability for A. obstetricans and A. cisternasii, indicating environmental segregation of the two species. Among the tree frogs, there was a strong positive correlation between favourability for H. meridionalis and for its overlap with H. molleri – i.e., sympatry occurs mainly in areas favourable for H. meridionalis. These results provide clues to understand the evolutionary history of these species, including the evolution of reproductive isolation, and suggest that conservation efforts for tree frogs may be focused on the areas that are favourable for both species, whereas midwife toads will require specific measures tailored for each species.

SUMMARY The purpose of this work has been to study the harvest and the conservation of pollen of ... more SUMMARY The purpose of this work has been to study the harvest and the conservation of pollen of the following species: E. camaldulensis Delinh, E. resinifera Smith, E. robusta Smith e E. tereticornis. The pollen was stored at 4oC and -10oC. Storage period ranged from just after harvesting until three months post-harvesting. Both temperature and period of storage gave significant

Surface and Coatings Technology

The present work explores effects of shelf-life, temperature and presence of cerium nitrate addit... more The present work explores effects of shelf-life, temperature and presence of cerium nitrate additive on the protective performance of sol-gel coatings applied on AA2024. These are important parameters when industrial applicability of coating formulations is considered. The studied sol-gel system is based on a combination of metalorganic precursor titanium(IV) propoxide and hybrid epoxy silane 3-glycidoxypropyltrimethoxysilane. The synthesized sol-gel formulations without or with addition of 0.007 M Ce(NO3)3 were aged during different times at temperatures 25 °C or -6 °C. FTIR results show that the intensities of the bands associated to Si-O-Si increase with respect to Si-OH groups during the ageing process as a result of extended condensation. However, such transformations occur less rapidly at low temperature. The electrochemical impedance spectroscopy measurements clearly show that sol-gel coatings corresponding to the sol-gel aged at low temperature exhibit similar corrosion prot...

A aplicabilidade da investigação laboratorial a contextos “reais” é um problema comummente discut... more A aplicabilidade da investigação laboratorial a contextos “reais” é um problema comummente discutido nas ciências sociais, em particular na psicologia experimental. Ou seja, até que ponto os estudos feitos em ambientes artificiais nos permitem retirar conclusões e aplicações em contextos “reais”? Este artigo propõe­‑se a contribuir para a desmistificação deste “problema”, recorrendo ao caso do efeito de ancoragem. O efeito de ancoragem – a assimilação de uma estimativa numérica sobre um alvo a um valor­‑standard – descrito inicialmente por Tversky e Kahneman (1974), cedo se revelou um efeito experimental extremamente consistente e com implicações práticas. Assim, revemos aqui exemplos de manifestações do efeito de ancoragem em diversos contextos, como nas decisões de consumo, económicas ou judiciais. Exploramos, ainda, as principais hipóteses explicativas do efeito de ancoragem e em que medida, essas teorias e testes às mesmas, permitiram compreender o fenómeno e gerar evidências das suas manifestações em variados contextos aplicados.DOI: http://dx.doi.org/10.17575/rpsicol.v26i2.274

Materials Science Forum, 2006

Materials Science Forum, 2006

Portugaliae Electrochimica Acta

ABSTRACT

Portugaliae Electrochimica Acta

ABSTRACT

Progress in Organic Coatings

... same concentration of chromate, zinc yellow has a high inhibitive power compared to other sim... more ... same concentration of chromate, zinc yellow has a high inhibitive power compared to other simple chromate ... applied to hot-dip galvanised steel (HDG) by dipping the substrates into the paint for 1 ... samples for the SVET study was chosen in order to allow a closer approach of the ...

Potentiometry with ion-selective microelectrodes measures activity of specific cations and anions... more Potentiometry with ion-selective microelectrodes measures activity of specific cations and anions at the solid/liquid interface from the solution side. Anodic and cathodic components of corrosion processes change local concentration of H+, OH-, metal cations and ions of the supporting electrolyte. These changes can be detected and quantified by SIET, making this technique an alternative, or complement, to methods based on potential and current changes across the interface. This mini-review describes SIET basics and demonstrates several examples of SIET applications relevant to corrosion studies.

Inhibitor-enriched protective coatings are able to tolerate mechanical impact followed by corrosi... more Inhibitor-enriched protective coatings are able to tolerate mechanical impact followed by corrosion attack. This is achieved via chemical interaction of corrosion inhibiting species with magnesium surface and formation of compact corrosion products that prevent further corrosion propagation and restore the main coating functionality: corrosion protection. Three main functional components contribute to success of a self-healing coating: durable polymer matrix, inhibitor repository and efficient corrosion inhibitor. This work describes our approach to composite protective coatings for WE43 magnesium alloy disclosing the details of all three main protective components. The combination of newly identified corrosion inhibitors for magnesium alloys was used to impart self-healing ability to fault-tolerant coatings. The results of electrochemical tests presented below demonstrate that developed composite coating provided enhanced long-term corrosion protection for the magnesium alloy, both...

The application fields of cerium compounds have enlarged in the last years. Cerium oxide is emerg... more The application fields of cerium compounds have enlarged in the last years. Cerium oxide is emerging as a hydrocarbon catalyst in self cleaning ovens and is now extensively used as a promoter in three- way catalysts (TWCs) for automotive emission control (1). This oxide allows for selective absorption of ultraviolet light in glass and, owing to its nonstoichiometric behaviour once the oxidation state of Ce can be 3+ or 4+, CeO2 also proved to be a good promoter for oxygen storage (2). The cerium oxide is also used in diesel fuels for a more complete combustion to abate soot formation (3). Moreover the magneto-optical signals of Ce-compounds have an outstanding figure of merit amongst other classes of magnetic materials (4). Synchrotron radiation is nowadays a powerful means of studying X-ray absorption fine-structure spectroscopy (XAFS), either close to the absorption edge (XANES) or up to a hundred electron volts above the edge (EXAFS). The latter has revealed itself as an outstand...

This paper presents an introduction to the SVET (Scanning Vibrating Electrode Technique). It star... more This paper presents an introduction to the SVET (Scanning Vibrating Electrode Technique). It starts with a brief historical account, followed by the operating principle, examples of application to corrosion, possible calculations, limitations, instrumentation, technical details and examples of its association with other electrochemical techniques.

Progress in Organic Coatings, 2015

ABSTRACT In this work we review results obtained using chitosan as a coating to protect aluminum ... more ABSTRACT In this work we review results obtained using chitosan as a coating to protect aluminum alloy 2024. Different inhibitors were added to the matrix, interaction between inhibitor and functional groups from chitosan investigated and functionalization of chitosan performed in the bulk, as well as at the coating/solution interface to improve the barrier properties. The obtained systems were characterized by proton-nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The protective performance was monitored using electrochemical impedance spectroscopy (EIS) and the scanning vibrating electrode technique (SVET). Overall, the obtained results support the possibility of using inhibitor-loaded chitosan systems to protect metallic substrates, either as components in multi-layer coatings systems, or as free-standing films.

Electrochimica Acta, 2015

ABSTRACT The direct use of high-ordered porous templates of anodic aluminium oxide for formation ... more ABSTRACT The direct use of high-ordered porous templates of anodic aluminium oxide for formation of nanostructures via electrochemical deposition is difficult because the presence of the of barrier alumina layer in the bottom of pores. In this paper, zinc electrodeposition from a solution of ZnCl2 in a choline chloride / ethylene glycol eutectic mixture on dense alumina layers of different thicknesses was studied. In a potentiostatic regime, the deposition on a barrier layer was found to be hardly possible even when the layer is a native alumina film (about 2 nm thick). Choline and ethylene glycol form an adsorbed stable layer at the alumina/electrolyte interface and thereby block the access of zinc chloride anions to the electrode.

ABSTRACT The study of areas of sympatry of species with predominantly parapatric distributions ma... more ABSTRACT The study of areas of sympatry of species with predominantly parapatric distributions may provide valuable insights about the factors shaping species occurrence. This information is key in biogeography, evolutionary biology and conservation planning. In this study we model the distributions of two pairs of partially co-occurring amphibian species in the Iberian Peninsula: tree frogs (Hyla molleri and H. meridionalis), with 11% of the occupied area shared by both species; and midwife toads (Alytes obstetricans and A. cisternasii), which co-occur in 4% of the total occupied area. We obtained distribution data from the herpetological atlases of Portugal and Spain, consisting of presences and absences on UTM 10x10-km grid cells. We built generalized linear models of presence / absence for each species and for the co-occurrence of each species pair, using 24 potential predictor variables representative of Iberian physiography, climate and human activity. Variables were selected for each model using information and significance criteria. The models were rated using calibration and discrimination measures and were compared using non-parametric correlation analysis after accounting for spatial autocorrelation. Preliminary results show a negative correlation between environmental favourability for A. obstetricans and A. cisternasii, indicating environmental segregation of the two species. Among the tree frogs, there was a strong positive correlation between favourability for H. meridionalis and for its overlap with H. molleri – i.e., sympatry occurs mainly in areas favourable for H. meridionalis. These results provide clues to understand the evolutionary history of these species, including the evolution of reproductive isolation, and suggest that conservation efforts for tree frogs may be focused on the areas that are favourable for both species, whereas midwife toads will require specific measures tailored for each species.

SUMMARY The purpose of this work has been to study the harvest and the conservation of pollen of ... more SUMMARY The purpose of this work has been to study the harvest and the conservation of pollen of the following species: E. camaldulensis Delinh, E. resinifera Smith, E. robusta Smith e E. tereticornis. The pollen was stored at 4oC and -10oC. Storage period ranged from just after harvesting until three months post-harvesting. Both temperature and period of storage gave significant

Surface and Coatings Technology

The present work explores effects of shelf-life, temperature and presence of cerium nitrate addit... more The present work explores effects of shelf-life, temperature and presence of cerium nitrate additive on the protective performance of sol-gel coatings applied on AA2024. These are important parameters when industrial applicability of coating formulations is considered. The studied sol-gel system is based on a combination of metalorganic precursor titanium(IV) propoxide and hybrid epoxy silane 3-glycidoxypropyltrimethoxysilane. The synthesized sol-gel formulations without or with addition of 0.007 M Ce(NO3)3 were aged during different times at temperatures 25 °C or -6 °C. FTIR results show that the intensities of the bands associated to Si-O-Si increase with respect to Si-OH groups during the ageing process as a result of extended condensation. However, such transformations occur less rapidly at low temperature. The electrochemical impedance spectroscopy measurements clearly show that sol-gel coatings corresponding to the sol-gel aged at low temperature exhibit similar corrosion prot...

A aplicabilidade da investigação laboratorial a contextos “reais” é um problema comummente discut... more A aplicabilidade da investigação laboratorial a contextos “reais” é um problema comummente discutido nas ciências sociais, em particular na psicologia experimental. Ou seja, até que ponto os estudos feitos em ambientes artificiais nos permitem retirar conclusões e aplicações em contextos “reais”? Este artigo propõe­‑se a contribuir para a desmistificação deste “problema”, recorrendo ao caso do efeito de ancoragem. O efeito de ancoragem – a assimilação de uma estimativa numérica sobre um alvo a um valor­‑standard – descrito inicialmente por Tversky e Kahneman (1974), cedo se revelou um efeito experimental extremamente consistente e com implicações práticas. Assim, revemos aqui exemplos de manifestações do efeito de ancoragem em diversos contextos, como nas decisões de consumo, económicas ou judiciais. Exploramos, ainda, as principais hipóteses explicativas do efeito de ancoragem e em que medida, essas teorias e testes às mesmas, permitiram compreender o fenómeno e gerar evidências das suas manifestações em variados contextos aplicados.DOI: http://dx.doi.org/10.17575/rpsicol.v26i2.274

Materials Science Forum, 2006

Materials Science Forum, 2006