Detalhes
Nome
Diana Filipa GuimarãesCluster
Redes de Sistemas InteligentesCargo
Investigador AuxiliarDesde
07 novembro 2016
Nacionalidade
PortugalCentro
Centro de Fotónica AplicadaContactos
+351220402301
diana.f.guimaraes@inesctec.pt
2022
Autores
Pessanha, S; Silva, AL; Guimaraes, D;
Publicação
X-RAY SPECTROMETRY
Abstract
2022
Autores
Ferreira, MFS; Capela, D; Silva, NA; Goncalves, F; Lima, A; Guimaraes, D; Jorge, PAS;
Publicação
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
Abstract
Laser-induced breakdown spectroscopy allows fast chemical analysis of light elements without significant sample preparation, turning it into a promising technique for on-site mining operations. Still, the performance for quantification purposes remains its major caveat, obstructing a broader application of the technique. In this work, we present an extensive comparison of the performances of distinct algorithms for quantification of Lithium in a mining prospection stage, using spectra acquired with both a commercial handheld device and a laboratory prototype. Covering both linear and non-linear methodologies, the results show that, when covering a wide range of concentrations typical on a mining operation, non-linear methodologies manage to achieve errors compatible with a semi-quantitative performance, offering performances better than those obtained with linear methods, which are more affected by saturation and matrix effects. The findings enclosed offer support for future applications in the field and may possibly be generalized for other elements of interest in similar mining environments.
2021
Autores
Ribeiro, R; Capela, D; Ferreira, M; Martins, R; Jorge, P; Guimaraes, D; Lima, A;
Publicação
MINERALS
Abstract
2019
Autores
Tehrani, MW; Huang, R; Guimaraes, D; Smieska, L; Woll, A; Parsons, PJ;
Publicação
JOURNAL OF TRACE ELEMENTS IN MEDICINE AND BIOLOGY
Abstract
Objective: The principal goal of this study was to investigate the uptake and distribution of lead (Pb) in the horns of Pb-dosed goats, and to explore possible links to their historical Pb dosing records. Horn is a keratinized material that grows in discrete increments with the potential to preserve the historical record of past environmental exposures. While previous studies have leveraged this potential to examine environmental and biological phenomena in horns, Pb uptake has never been explored. Methods: Horns were collected post-mortem from three goats that had been previously used to produce blood lead reference materials for the New York State proficiency testing program. The animals were periodically dosed with lead acetate, administered orally in a capsule, over a 5 to 8-year period. Horn cross sections were taken from each animal and analyzed using synchrotron radiation-induced micro X-ray fluorescence spectrometry (SR-µXRF) at the Cornell High Energy Synchrotron Source (CHESS). Results: Elemental distribution maps were obtained by SR-µXRF for Pb, Ca, S, Se, and three other elements (Br, Zn and Cu), with values reported quantitatively as a mass fraction (µg/g for trace elements and mg/g for Ca and S). Accumulations of Pb were clearly visible as a series of narrow “rings” in each of the horn samples analyzed. The elements Ca, S, Br, Zn, and Cu were also detected as discrete rings within each cross-section, with Br strongly correlated with S in the samples examined. A marginal increase in Se may coincide with Pb accumulation in horn cross-sections. Annual mineralization estimates based on the relative distribution of Ca and S were used to establish a tentative timeline for horn growth, with each timeline linked to the pattern of Pb accumulation in the corresponding horn cross-section sample. Conclusions: Following ingestion, absorbed Pb is eventually deposited into caprine horns, resulting in discrete accumulations or “rings.” Elemental mapping by SR-µXRF clearly show Ca-rich layers that vary with annual periodicity, consistent with previous reports of horn mineralization. Localized enrichment of Cu, Zn, Br and S appear to coincide with the keratinized regions related to the annual growth ring pattern in horns. Spatial analysis of horns for Pb accumulation may be useful as a qualitative marker of time-resolved exposures that may reflect specific periods of acute Pb absorption. © 2019 Elsevier GmbH
2019
Autores
Guimaraes, D; Ferreira, MFS; Ribeiro, R; Dias, C; Lima, A; Martins, RC; Jorge, PAS;
Publicação
FOURTH INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS
Abstract
A high-resolution advanced laser induced breakdown spectroscopy prototype was used to quantify lithium (Li) in lithiniferous rocks. Samples were collected from Barroso's mine (Portugal), claimed as Western Europe's largest spodumene Li discovery. 51 samples from a reverse circulation drill were collected, one for each meter interval, dried, milled, pressed into pellets and further analyzed by laser induced breakdown spectroscopy. Quantification was attempted using either linear models based on the intensity of selected Li spectral lines or advanced chemometrics methods. The latter was very successful, with correlation coefficients of 0.97 against certified laboratory results. © 2019 SPIE.
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