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306 results on '"Miguel, A.S."'

13. The Gondwanide deformation along the southwestern border of the Río de la Plata Craton: Geochemical and geochronological constraints on ductile shear zones from the Ventania System basement, Argentina

Author

Ballivián Justiniano, Carlos A., Oriolo, Sebastián, Basei, Miguel A.S., Lanfranchini, Mabel E., Christiansen, Rodolfo O., Uriz, Norberto J., Vázquez Lucero, Sebastián E., Del Bono, Daniela A., Forster, Marnie A., Etcheverry, Ricardo O., Tassinari, Colombo C.G., Comerio, Marcos A., and Prezzi, Claudia B.

Published
2023
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14. A Comparative Study of Surface Plasmon and Tamm Plasmon Polaritons for Hydrogen Sensing.

Author

Almeida, Miguel A.S., Carvalho, João P.M., Pastoriza-Santos, Isabel, Almeida, José M.M.M., and Coelho, Luís C.C.

Subjects
*SURFACE plasmons, *POLARITONS, *HYDROGEN detectors, *ENERGY consumption, *CARBON emissions
Abstract

Due to the exponential increase in energy consumption and CO2 emissions, new sustainable energy sources have emerged, and hydrogen (H2) is one of them. Despite all the advantages, H2 has high flammability, so constant monitoring is essential. Two optical techniques were numerically studied and compared with the goal of H2 sensing: surface plasmon polaritons (SPP) and Tamm plasmon polaritons (TPP). The H2-sensitive material used was palladium (Pd) in both techniques. The SPP structure was found to have more sensitivity to H2 than TPP, 23 and 5nm/4vol% H2, respectively. However, the latter has lower FWHM, with the minimum of the band showing reflectivity near 0%. In addition, TPP also uses more costeffective materials and can be interrogated at normal incidence with depolarized light. The potential of using each of these optical techniques for H2 sensing was demonstrated. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Comparative Analysis of Ethanol Gas Sensors Based on Bloch Surface Wave and Surface Plasmon Resonance.

Author

Carvalho, João P.M., Almeida, Miguel A.S., Mendes, João P., Coelho, Luís C.C., and De Almeida, José M.M.M.

Subjects
*GAS detectors, *ETHANOL, *ELECTROMAGNETIC waves, *SURFACE plasmon resonance, *ZINC oxide
Abstract

Ethanol plays a crucial role in modern industrial processes and consumer products. Despite its presence in human activity, short and long-term exposure to gaseous ethanol poses risks to health conditions and material damage, making the control of its concentration in the atmosphere of high importance. Ethanol optical sensors based on electromagnetic surface waves (ESWs) are presented, with sensitivity to ethanol vapours being achieved by the inclusion of ethanol-adsorptive zinc oxide (ZnO) layers. The changes in optical properties modulate the resonant conditions of ESWs, enabling the tracking of ethanol concentration in the atmosphere. A comprehensive comparative study of sensor performance is carried out between surface plasmon resonance (SPR) and Bloch surface wave (BSW) based sensors. Sensor efficiency is simulated by transfer matrix method towards optimized figures of merit (FoM). Preliminary results validate ethanol sensitivity of BSW based sensor, showcasing a possible alternative to electromagnetic and plasmonic sensors. [ABSTRACT FROM AUTHOR]

Published
2024
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21. A conceptual model for the evolution of a magmatic system based on U-Pb zircon studies on the Devonian granites of Sierra de San Luis, Argentina

Author

Dahlquist, Juan A., Morales Cámera, Matías M., Moreno Moreno, Juan Antonio, Basei, Miguel A.S., Santos da Cruz, Gilmara, Oliveira, Elson P., Dahlquist, Juan A., Morales Cámera, Matías M., Moreno Moreno, Juan Antonio, Basei, Miguel A.S., Santos da Cruz, Gilmara, and Oliveira, Elson P.

Abstract

It is widely acknowledged that thermal models clearly demonstrate that crustal magma bodies should solidify rapidly upon emplacement. Small plutons can cool below the solidus in thousands of years, while even large plutons require hundreds of thousands of years, but not more than a million years. However, recent U-Pb zircon geochronological data contradict these results, strongly suggesting that magmatic systems are often characterized by protracted events. Therefore, a conceptual framework that reconciles thermal models and the geochronology data is necessary. The Devonian foreland magmatism of the Sierra de San Luis is made up of two distinctive suites, the Monzonite suite (<65 wt.% SiO2) and the Granite suite (>65 wt.% SiO2), both emplaced at ca. 3.7 kbar. Classification of the studied Devonian granitoids is debatable because they have a hybrid I- to A-type granite signature. Based on a robust geochronological U-Pb zircon dataset we corroborate the development of a protracted magmatic activity with three major crystallization events for this Devonian magmatism: 391 ± 1, 384 ± 1, and 379 ± 2 Ma. Considering these geochronological data, we postulate the presence of a deep mush reservoir, where a prolonged magmatic activity, permitted the prolonged crystallization of antecrysts (ca. 395–384 Ma). Migration of the parental magma from the mush reservoir zone occurred near the time of emplacement and culminated in the formation of an ephemeral magma chamber located at shallow levels, where zircon autocrysts crystallized (ca. 379 Ma). Age spectra reported within individual samples support the idea of a massive migration of magma when conditions were favourable (e.g. thermally matured crust). Individual crystallization ages recorded by monazites hosted in two-mica granites are comparable to those obtained from zircons, supporting the presence of a long-lasting hot source. Additional geochronological data indicate that a later thermal event (ca. 353 Ma) could have partiall, Consejo Nacional de Investigaciones Científicas y Técnicas, Fondo para la Investigación Científica y Tecnológica, Fundação de Amparo à Pesquisa do Estado de São Paulo, Secretaria de Ciencia y Tecnología - Universidad Nacional de Córdoba, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Published
2024

36. Petrography descriptions and U-Pb zircon datasets from the Archean Pavas Block, Precambrian of Uruguay

Author

Henri Masquelin, Tahar Aïfa, Fernando Scaglia, and Miguel A.S. Basei

Subjects
Gneiss complex, Nico Pérez Terrane, Zircon texture, Orosirian, U-Pb geochronology, Computer applications to medicine. Medical informatics, R858-859.7, Science (General), Q1-390
Abstract

This database is a geological and geochronological compilation made to study a small Archean/Paleoproterozoic block located in the centre of the Precambrian rock exposition of Uruguay. Petrographic and field outcrops data supporting the samples from which the zircons for textural analysis and U-Pb dating (LA-ICP-MS) come are presented at first with their descriptions. The first table (1) contains the new U-Pb isotopic data. The second table (2) presents a correlation of textures from different zircon samples. The last table (3) contains an inventory of different U-Pb ages found in antecedents. All these data are associated with the paper entitled: “The Archean Pavas Block in Uruguay: extension and tectonic evolution based on LA-ICP-MS U-Pb ages and airborne geophysics”.

Published
2021
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