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About

About

I was born in Lisbon, Portugal, in 1983 and graduated from Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa (FCT-UNL) in Physics Engineering in 2006. My undergraduate research consisted in developing and assembly of a specialized X-ray fluorescence spectrometer. This work lead to a Master in Physics Engineering (FCT-UNL, 2007) and a PhD in Atomic Physics (FCT-UNL, 2011) entitled: “Measurement of lead concentration in biological tissues by atomic spectroscopy techniques”.

In 2012, I moved to Albany (New York, USA) as a Postdoc in Analytical Chemistry, to work at the Trace Elements group, Wadsworth Center New York State Department of Health. In the same year I transitioned to a Research Scientist position and became supervisor of the X-ray lab. Here I participated in multiple projects concerning biomonitoring and environmental analysis of trace elements in several matrices (food, cosmetics, medicines, consumer products, human tissues and body fluids) using analytical techniques based on atomic spectrometry, including synchrotron radiation at the Cornell University. I also spent 2 years as a Research Assistant Professor at the University at Albany, State University of New York – School of Public Health, Department of Environmental Health Sciences.

In 2016 I decided to shift my research focus from atomic to nuclear radiation.  I moved to Porto, Portugal, and I am currently working at INESC-TEC developing fiber optic sensors to detect the presence of Radon, a radioactive element, in marine environments.

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Details

002
Publications

2019

A study of lead uptake and distribution in horns from lead-dosed goats using synchrotron radiation-induced micro X-ray fluorescence elemental imaging

Authors
Tehrani, MW; Huang, R; Guimarães, D; Smieska, L; Woll, A; Parsons, PJ;

Publication
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

2018

Characterization of arsenic in dried baby shrimp (Acetes sp.) using synchrotron-based X-ray spectrometry and LC coupled to ICP-MS/MS

Authors
Guimaraes, D; Roberts, AA; Tehrani, MW; Huang, R; Smieska, L; Woll, AR; Lin, S; Parsons, PJ;

Publication
Journal of Analytical Atomic Spectrometry

Abstract
The arsenic content of dried baby shrimp (Acetes sp.) was investigated as part of an independent field study of human exposure to toxic metals/metalloids among the ethnic Chinese community located in Upstate New York. The dried baby shrimp were analyzed in a home environment using a portable X-Ray Fluorescence (XRF) instrument based on monochromatic excitation. Study participants had obtained their dried baby shrimp either from a local Chinese market or prepared them at home. The shrimp are typically between 10-20 mm in size and are consumed whole, without separating the tail from the head. Elevated levels of As were detected using portable XRF, ranging between 5-30 µg g-1. Shrimp samples were taken to the Cornell High Energy Synchrotron Source (CHESS) for Synchrotron Radiation µXRF (SR-µXRF) elemental mapping using a 384-pixel Maia detector system. The Maia detector provided high resolution trace element images for As, Ca, and Br, (among others) and showed localized accumulation of As within the shrimp's cephalothorax (head), and various abdominal segments. As quantification by SR-µXRF was performed using a lobster hepatopancreas reference material pellet (NRC-CNRC TORT-2), with results in good agreement with both portable XRF and ICP-MS. Additional As characterization using µX-ray Absorption Near Edge Spectroscopy (µXANES) with the Maia XRF detector at CHESS identified arsenobetaine and/or arsenocholine as the possible As species present. Further arsenic speciation analysis by LC-ICP-MS/MS confirmed that the majority of As (>95%) is present as the largely non-toxic arsenobetaine species with trace amounts of arsenocholine, methylated As and inorganic As species detected. © The Royal Society of Chemistry.

2018

Development of a new system for real-time detection of radon using scintillating optical fibers

Authors
Monteiro, CS; Coelho, L; Barbosa, SM; Guimarães, D;

Publication
Optics InfoBase Conference Papers

Abstract
A remote sensor for radon continuous measurement using polymeric scintillation optical fibers was developed and evaluated. Successful preliminary results showed detection of natural occurring radon from a container with rocks rich in uranium oxides. © OSA 2018 © 2018 The Author(s)

2017

Assessing arsenic and selenium in a single nail clipping using portable X-ray fluorescence

Authors
Fleming, DEB; Nader, MN; Foran, KA; Groskopf, C; Reno, MC; Ware, CS; Tehrani, M; Guimaraes, D; Parsons, PJ;

Publication
APPLIED RADIATION AND ISOTOPES

Abstract
The feasibility of measuring arsenic and selenium contents in a single nail clipping was investigated using a small-focus portable X-ray fluorescence (XRF) instrument with monochromatic excitation beams. Nail clipping phantoms supplemented with arsenic and selenium to produce materials with 0, 5, 10, 15, and 20 mu g/g were used for calibration purposes. In total, 10 different clippings were analyzed at two different measurement positions. Energy spectra were fit with detection peaks for arsenic K-alpha, selenium K-alpha, arsenic K-beta, selenium K-beta, and bromine K-alpha characteristic X-rays. Data analysis was performed under two distinct conditions of fitting constraint. Calibration lines were established from the amplitude of each of the arsenic and selenium peaks as a function of the elemental contents in the clippings. The slopes of the four calibration lines were consistent between the two conditions of analysis. The calculated minimum detection limit (MDL) of the method, when considering the Ka peak only, ranged from 0.210 +/- 0.002 mu g/g selenium under one condition of analysis to 0.777 +/- 0.009 mu g/g selenium under another. Compared with previous portable XRF nail clipping studies, MDLs were substantially improved for both arsenic and selenium. The new measurement technique had the additional benefits of being short in duration (similar to 3 min) and requiring only a single nail clipping. The mass of the individual clipping used did not appear to play a major role in signal strength, but positioning of the clipping is important.

2016

Quantitative determinations and imaging in different structures of buried human bones from the XVIII-XIXth centuries by energy dispersive X-ray fluorescence - Postmortem evaluation

Authors
Guimaraes, D; Dias, AA; Carvalho, M; Carvalho, ML; Santos, JP; Henriques, FR; Curate, F; Pessanha, S;

Publication
TALANTA

Abstract
In this work, a non-commercial triaxial geometry energy dispersive X-ray Fluorescence (EDXRF) setup and a benchtop mu-XRF system were used to identify postmortem contamination in buried bones. For two of the individuals, unusually high concentrations of Cu and Pb, but also Zn (in one individual) were observed. The pigments of the burial shroud coverings have been identified as the source of contamination. Accurate and precise quantitative results were obtained by nondestructive process using fundamental parameters method taking into account the matrix absorption effects. A total of 30 bones from 13 individuals, buried between the mid-XVlllth to early XIXth centuries, were analyzed to study the elemental composition and elemental distribution. The bones were collected from a church in Almada (Portugal), called Ermida do Espirito Santo, located near the Tagus River and at the sea neighbourhood. The triaxial geometry setup was used to quantify Ca, Fe, Cu, Zn, Br, Sr and Pb of powder pressed bone pellets (n=9 for each bone). Cluster analysis was performed considering the elemental concentrations for the different bones. There was a clear association between some bones regarding Fe, Cu, Zn, Br and Pb content but not a categorization between cortical and trabecular bones. The elemental distribution of Cu, Zn and Pb were assessed by the benchtop p.-analysis, the M4 Tornado, based on a polycapillary system which provides multi-elemental 2D maps. The results showed that contamination was mostly on the surface of the bone confirming that it was related to the burial shroud covering the individuals.