João Leitão, Joaquim Ferreira, Ernesto D.R. Santibañez González,
Abstract This study assesses the non‐linear effects of green bonds, conventional bonds and energy commodities on the behaviour of the cap‐and‐trade European Union carbon market (European Union Emissions Trading System [EU‐ETS]). By estimating four models, using Markov‐switching (MS) econometric methodology, non‐linearities are confirmed in dynamic behaviours, observing in the global calculation a positive effect of green bonds ( S&P Green and Sol Green ) on the carbon market, in regimes of both high ...
Tópico(s): Energy, Environment, Economic Growth
2021 - Wiley | Business Strategy and the Environment
João Leitão, Joaquim Ferreira, Ernesto D.R. Santibañez González,
Overall, the literature strongly validates the Environmental Kuznets Curve hypothesis and the decoupling of the economy regarding energy intensity and raw materials. However, there is no assessment of whether such evidence derives from the non-linearities of macroeconomic fundamentals from considering a simultaneous supply-demand market perspective of material flows. Therefore, using a sample of 40 countries, we estimated a Panel Smooth Transition Regression model for the period between 1994 and ...
Tópico(s): Environmental Impact and Sustainability
2021 - Elsevier BV | Technological Forecasting and Social Change
Sarmento J. Mazivila, Juan M. Lombardi, Ricardo N.M.J. Páscoa, Santiago A. Bortolato, João M.M. Leitão, Joaquim C. G. Esteves da Silva,
Tópico(s): Spectroscopy Techniques in Biomedical and Chemical Research
2020 - Elsevier BV | Analytica Chimica Acta
Produção Nacional
Revisado por pares
Sarmento J. Mazivila, Ivo A. Ricardo, João M.M. Leitão, Joaquim C. G. Esteves da Silva,
This paper offers a critical review from classical to new perspectives of advanced oxidation processes (AOPs) coupled to two- and multi-way calibration strategies based on multivariate curve resolution – alternating least-squares (MCR-ALS) and parallel factory analysis (PARAFAC) with various analytical techniques to monitor the degradation of contaminants in environmental samples. It focuses on the generation of highly reactive hydroxyl (HO•) radicals (classical AOPs with emphasis on Fenton, photo-Fenton ...
Tópico(s): Electrochemical Analysis and Applications
2019 - Elsevier BV | Trends in Environmental Analytical Chemistry
Sarmento J. Mazivila, Ricardo A. E. Castro, João M.M. Leitão, Joaquim C. G. Esteves da Silva,
This paper, reports for the first time the green synthesis of the polymorphs I and II of new pharmaceutical co-crystals lamivudine:theophylline in solid-phase, through the mixture between lamivudine and theophylline (both active pharmaceutical ingredients-APIs) in the proportion of 1:1 by neat grinding and liquid assisted grinding (10 μL ethanol). Fourier transform-infrared (FT-IR) spectroscopy and multivariate curve resolution with alternating least-squares (MCR-ALS) were employed as non-invasive analytical ...
Tópico(s): Drug Solubulity and Delivery Systems
2019 - Elsevier BV | Journal of Pharmaceutical and Biomedical Analysis
Eliana F. C. Simões, João M.M. Leitão, Joaquim C. G. Esteves da Silva,
Microwave synthetized sulfur and nitrogen co-doped carbon dots responded selectively to nitric oxide (NO) at pH 7. Citric acid, urea and sodium thiosulfate in the proportion of 1:1:3 were used respectively as carbon, nitrogen and sulfur sources in the carbon dots microwave synthesis. For this synthesis, the three compounds were diluted in 15 mL of water and exposed for 5 min to a microwave radiation of 700 W. It is observed that the main factor contributing to the increased sensitivity and selectivity ...
Tópico(s): Advanced Nanomaterials in Catalysis
2017 - Elsevier BV | Analytica Chimica Acta
Eliana F. C. Simões, João M.M. Leitão, Joaquim C. G. Esteves da Silva,
Tópico(s): Electrochemical sensors and biosensors
2016 - Springer Science+Business Media | Microchimica Acta
João M.M. Leitão, Joaquim C. G. Esteves da Silva,
Firefly luciferase (Luc) is the most studied of the luciferase enzymes and the mechanism and kinetics of the reactions catalyzed by this enzyme have been relatively well characterized. Luc catalyzes the bioluminescent reaction involving firefly luciferin (D-LH(2)), adenosine triphosphate (ATP), magnesium ion and molecular oxygen with the formation of an electronically excited species (oxyluciferin), inorganic pyrophosphate (PPi), carbon dioxide and adenosine monophosphate (AMP). Luc also catalyzes other ...
Tópico(s): Tardigrade Biology and Ecology
2010 - Elsevier BV | Journal of Photochemistry and Photobiology B Biology
João M.M. Leitão, Joaquim C. G. Esteves da Silva,
A Diltiazem kinetic spectrophotometric UV–Vis method, based on a reaction of the Diltiazem with hidroxylamine and a ferric salt, was used for the quantification of Diltiazem in different pharmaceutical formulations. This method is based on the acquisition of three-way data structures [wavelength (nm) × time (s) × concentration (mg/L)] followed by chemometric analysis by an appropriate PARAFAC2 or MCR-ALS second-order calibration model. The results obtained are compared with those obtained by direct determination, ...
Tópico(s): Pesticide Residue Analysis and Safety
2007 - Elsevier BV | Chemometrics and Intelligent Laboratory Systems
João M.M. Leitão, Joaquim C. G. Esteves da Silva,
A Diltiazem kinetic spectrophotometric method was optimized by factorial analysis.The experimental method is based on a two-stage reaction of Diltiazem with hydroxylamine and a ferric salt: in the first stage there is a hydroxamic acid formation; and, in the second stage there is a red colour complex ferric hydroxamate formation.The variables under investigation were: solvent; hydroxylamine, sodium hydroxide and ammonium ferric sulphate concentrations; volume of perchloric acid; and, temperature. ...
Tópico(s): Analytical Chemistry and Sensors
2008 - Elsevier BV | Analytica Chimica Acta
João M.M. Leitão, Joaquim C. G. Esteves da Silva, A. Jiménez Girón, Arsenio Muñoz de la Peña,
Excitation emission fluorescence matrices (EEMs) of Verapamil drug were obtained by direct and by derivatization fluorescence spectroscopy. The fluorescence excitation and emission wavelengths were displaced to longer wavelengths and the fluorescence intensity was enhanced upon derivation with respect to the native fluorescence of the drug. The complete EEM of the native fluorescence of the drug and of the derivatization product were rapidly acquired by using a charged-coupled device detector (CCD), ...
Tópico(s): Analytical Methods in Pharmaceuticals
2008 - Springer Science+Business Media | Journal of Fluorescence
Joaquim Leitão, Paulo Gil, Bernardete Ribeiro, Alberto Cardoso,
Energy is a vital resource for human activities and lifestyle, powering important everyday infrastructures and services. Currently, pollutant and non-renewable sources, such as fossil fuels, remain the main source of worldwide consumed energy. The environmental impact of their exploitation has boosted research and investments in alternative, clean and renewable sources, including photovoltaic and wind-based systems. As a whole, buildings are one of the major energy consumption sectors. Hence, improving ...
Tópico(s): Microgrid Control and Optimization
2020 - Institute of Electrical and Electronics Engineers | IEEE Access
Alberto Cardoso, Joaquim Leitão, César Teixeira,
Teaching and learning processes can benefit from the use of online resources, enabling the improvement of teachers and students productivity and giving them flexibility and support for collaborative work. Particularly in engineering courses, open source tools, such as Jupyter Notebook, provide a programming environment for developing and sharing educational materials, combining different types of resources such as text, images and code in several programming languages in a single document, accessible ...
Tópico(s): Online Learning and Analytics
2019 - Springer Nature | Advances in intelligent systems and computing
Joaquim Leitão, Nuno Simões, Alfeu Sá Marques, Paulo Gil, Bernardete Ribeiro, Alberto Cardoso,
Abstract The need for efficient management of water distribution systems is a growing concern for economic, environmental and social reasons. Water supply systems are commonly designed to ensure adequate behaviour under the worst conditions, such as maximum consumption, which leads to overestimation in supply tanks and energy waste. While overestimation should be considered, to account for unpredictable demands and emergency scenarios, we advocate that a detailed understanding of consumption patterns ...
Tópico(s): Water resources management and optimization
2019 - IWA Publishing | Water Science & Technology Water Supply
Henrique Leitão, Joaquim Alves Gaspar,
In this paper we show that, for historical reasons, the most likely way for Mercator to have drawn his map was by using a table of rhumbs. This is argued by examining in some detail the development of the concept of a rhumb line from its initial articulation by Pedro Nunes in 1537 to its advanced treatment in 1566. We also describe the intellectual debate that took place around this topic in Europe during that period. A hitherto neglected Portuguese source of about 1540, where tables of rhumbs are ...
Tópico(s): Optics and Image Analysis
2014 - Taylor & Francis | Imago Mundi
João M.M. Leitão, Joaquim C. G. Esteves da Silva,
Two-way data structures were obtained by acquiring UV–vis spectra as function of the time of the alkaline hydrolysis reaction of the antihypertensor Nifedipine in dimethylsulfoxide (DMSO). Sets of three-way data structures were obtained from the analysis of solutions with different concentrations of Nifedipine generated by standard additions to DMSO, Nifedipine standard and a pharmaceutical formulation. PARAFAC and PARAFAC2 methods were used in the analysis of these multi-way data structures and ...
Tópico(s): Computational Drug Discovery Methods
2006 - Elsevier BV | Analytica Chimica Acta
Jorge C. Pereira, Pedro G. Lino, Alexandra Leitão, Sandra Joaquim, Raquel Chaves, P. Pousãao-Ferreira, Henrique Guedes‐Pinto, Miguel N. Santos,
Tópico(s): Genetic and phenotypic traits in livestock
2010 - Springer Nature | Journal of Applied Genetics
Inês Sequeira, M.A. Pires, José Carlos Leitão, Joaquim Henriques, Carlos Viegas, João Requicha,
Feline oral squamous cell carcinoma (FOSCC) is the most common oral neoplasia in cats. This malignant tumor is locally invasive, has a high mortality rate, and its etiology is not yet known. In humans, head and neck squamous cell carcinoma is associated with tobacco smoke, alcohol consumption, and human papillomavirus infection. Herein, a critical review about the potential etiologic factors of FOSCC was performed, considering publications between 2000 and 2022, aiming to synthesize all available ...
Tópico(s): Microbial infections and disease research
2022 - Multidisciplinary Digital Publishing Institute | Veterinary Sciences
Eliana F. C. Simões, João M.M. Leitão, Joaquim C. G. Esteves da Silva,
Tópico(s): Advanced Nanomaterials in Catalysis
2013 - Springer Science+Business Media | Journal of Fluorescence
Produção Nacional
Revisado por pares
Danilo Ribeiro de Oliveira, André Luiz Maiocchi Alves Costa, Gilda Guimarães Leitão, Newton G. Castro, Joaquim Pereira dos Santos, Suzana Guimarães Leitão,
Um levantamento etnobotânico realizado em comunidades quilombolas de Oriximiná, Pará, destacou a saracuramirá (SAR), Ampelozizyphus amazonicus Ducke, com vasto uso popular no tratamento da malária, como tônica e depurativa. Por este motivo, o presente trabalho objetivou realizar um estudo etnofarmacognóstico da SAR nas respectivas comunidades. Por meio de uma análise etnobotânica quantitativa, foi verificado que SAR apresentou-se dentre as 10 espécies mais versáteis pela elevada importância relativa ( ...
Tópico(s): Natural product bioactivities and synthesis
2011 - INSTITUTO NACIONAL DE PESQUISAS DA AMAZÔNIA | Acta Amazonica
Marco A. Curado, Jennifer P. Teixeira, Margarida Monteiro, Eduardo F M Ribeiro, R. C. Vilão, H.V. Alberto, José M. V. Cunha, Tomás S. Lopes, Kevin Oliveira, Olivier Donzel‐Gargand, Adam Hultqvist, Sebastián Calderón, M.A. Barreiros, William Chiappim, Joaquim P. Leitão, Ana G. Silva, T. Prokscha, Carlos Vinhais, Paulo A. Fernandes, P.M.P. Salomé,
In the past years, the strategies used to break the Cu(In,Ga)Se2 (CIGS) light to power conversion efficiency world record value were based on improvements of the absorber optoelectronic and crystalline properties, mainly using complex post-deposition treatments. To reach even higher efficiency values, further advances in the solar cell architecture are needed, in particular, with respect to the CIGS interfaces. In this study, we evaluate the structural, morphological and optoelectronic impact of ...
Tópico(s): Semiconductor materials and interfaces
2020 - Elsevier BV | Applied Materials Today
Paulo A. Fernandes, Aigul Shongalova, A.F. da Cunha, Jennifer P. Teixeira, Joaquim P. Leitão, José M. V. Cunha, Sourav Bose, P.M.P. Salomé, M. R. Correia,
In this work, we present a procedure to grow Cu12Sb4S13 and Cu3SbS4 thin films consisting of the deposition of simultaneously sputtered metal precursors followed by a annealing treatment in a sulphur atmosphere. The selection of the ternary phase is performed by adjusting the sulphur evaporation temperature in the chalcogenization process. It is shown that for a sulphur evaporation temperature of 140 ∘C the predominant phase is Cu12Sb4S13 while for 180 ∘C the predominant phase is Cu3SbS4. In order ...
Tópico(s): Quantum Dots Synthesis And Properties
2019 - Elsevier BV | Journal of Alloys and Compounds
Bruno P. Falcão, Joaquim P. Leitão, M.R. Soares, Lídia Ricardo, Hugo Águas, Rodrigo Martins, Rui N. Pereira,
Understanding the effects of surface-related strain is important in developing technologies based on nanoscale forms of silicon. This investigation of physical phenomena related to surface oxidation of free-standing silicon nanocrystals (Si-NCs) reveals strongly surface-dependent lattice strain. The time evolution of natural oxidation in air shows a clear correlation between oxide formation and the appearance of compressive strain in a Si-NC's core. Strain is negligible in H-terminated nanocrystals, ...
Tópico(s): Semiconductor materials and devices
2019 - American Physical Society | Physical Review Applied
Jennifer P. Teixeira, P.M.P. Salomé, Bruno Alves, Marika Edoff, Joaquim P. Leitão,
Cu(In,Ga)Se${}_{2}$ (CIGS) yields really promising solar cells, but defects and local variations in the composition of this complex alloy also cause modifications to its electronic structure. Understanding the influence of fluctuating potentials on performance is of utmost importance for CIGS-based solar cells. A detailed theoretical study of these fluctuating potentials is developed, and compared to experimental results. The results show unequivocally that losses in open-circuit voltage are correlated ...
Tópico(s): Copper-based nanomaterials and applications
2019 - American Physical Society | Physical Review Applied
Bruno P. Falcão, Joaquim P. Leitão, Hugo Águas, Rui N. Pereira,
The effects of anisotropy and splitting of the phonon dispersions in the Raman spectrum of nanocrystals are investigated. We describe the different branches of the optical phonon dispersion curves along each high-symmetry direction by fitting a simple empirical model to experimental data. These curves are then used to calculate the Raman spectrum in the framework of the phonon confinement model and the results are compared with a wide range of available experimental data as well as with the spectra ...
Tópico(s): Spectroscopy Techniques in Biomedical and Chemical Research
2018 - American Physical Society | Physical review. B./Physical review. B
H. V. Alberto, R. C. Vilão, Ricardo Vieira, J. M. Gil, A. Weidinger, M.G. Sousa, Jennifer P. Teixeira, A.F. da Cunha, Joaquim P. Leitão, P.M.P. Salomé, Paulo A. Fernandes, Tobias Törndahl, T. Prokscha, A. Suter, Z. Salman,
Thin films and $p\ensuremath{-}n$ junctions for solar cells based on the absorber materials $\mathrm{Cu}(\mathrm{In},\mathrm{G}\mathrm{a}){\mathrm{Se}}_{2}$ and ${\mathrm{Cu}}_{2}{\mathrm{ZnSnS}}_{4}$ were investigated as a function of depth using implanted low energy muons. The most significant result is a clear decrease of the formation probability of the ${\mathrm{Mu}}^{+}$ state at the heterojunction interface as well as at the surface of the $\mathrm{Cu}(\mathrm{In},\mathrm{G}\mathrm{a}){\mathrm{Se}}_{ ...
Tópico(s): Quantum Dots Synthesis And Properties
2018 - American Physical Society | Physical Review Materials
Sourav Bose, José M. V. Cunha, Jérôme Borme, Wen‐Chang Chen, Nina Shariati Nilsson, Jennifer P. Teixeira, J. Gaspar, Joaquim P. Leitão, Marika Edoff, Paulo A. Fernandes, P.M.P. Salomé,
The effects of introducing a passivation layer at the rear of ultrathin Copper Indium Gallium di-Selenide Cu(In,Ga)Se2 (CIGS) solar cells is studied. Point contact structures have been created on 25 nm Al2O3 layer using e-beam lithography. Reference solar cells with ultrathin CIGS layers provide devices with average values of light to power conversion efficiency of 8.1% while for passivated cells values reached 9.5%. Electronic properties of passivated cells have been studied before, but the influence ...
Tópico(s): Semiconductor materials and interfaces
2018 - Elsevier BV | Thin Solid Films
José M. V. Cunha, Paulo A. Fernandes, Adam Hultqvist, Jennifer P. Teixeira, Sourav Bose, Bart Vermang, Siddhartha Garud, Dilara G. Buldu, J. Gaspar, Marika Edoff, Joaquim P. Leitão, P.M.P. Salomé,
In this work, metal–insulator–semiconductor structures were fabricated in order to study different types of insulators, namely, aluminum oxide (Al 2 O 3 ), silicon nitride, and silicon oxide (SiO x ) to be used as passivation layers in Cu(In,Ga)Se 2 (CIGS) thin-film solar cells. The investigated stacks consisted of SLG/Mo/CIGS/insulator/Al. Raman scattering and photoluminescence measurements were done to verify the insulator deposition influence on the CIGS surface. In order to study the electrical properties ...
Tópico(s): Copper-based nanomaterials and applications
2018 - Institute of Electrical and Electronics Engineers | IEEE Journal of Photovoltaics
Produção Nacional
Revisado por pares
Aigul Shongalova, M. R. Correia, Jennifer P. Teixeira, Joaquim P. Leitão, J. C. González, Samaneh Ranjbar, Siddhartha Garud, Bart Vermang, José M. V. Cunha, P.M.P. Salomé, Paulo A. Fernandes,
In this work we present a method to grow Sb2Se3 thin films with a potential use as absorber layers in solar cell structures. The films were grown on several substrates: soda-lime glass, Mo coated soda-lime glass and Si. The Sb-Se precursor's films were deposited by RF magnetron sputtering and then selenized under a H2Se gas flow. Different selenization temperatures were tested and analysed. Compositional and morphological analyses were performed by Energy Dispersive Spectroscopy and Scanning Electron ...
Tópico(s): Phase-change materials and chalcogenides
2018 - Elsevier BV | Solar Energy Materials and Solar Cells
M.G. Sousa, A.F. da Cunha, Jennifer P. Teixeira, Joaquim P. Leitão, Gonzalo Otero‐Irurueta, Manoj K. Singh,
In this work we present an optimization of the post-deposition annealing, in Cu2ZnSnS4 (CZTS) thin film solar cells, applied at different stages of the solar cell preparation, namely, bare CZTS absorber, CZTS/CdS heterojunction and CZTS/CdS/i-ZnO/ITO complete solar cell. We performed current-density measurements, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman scattering, photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) studies ...
Tópico(s): Copper-based nanomaterials and applications
2017 - Elsevier BV | Solar Energy Materials and Solar Cells