Entity

Time filter

Source Type

Évora, Portugal

Rosado T.,University of Evora | Mirao J.,University of Evora | Candeias A.,University of Evora | Caldeira A.T.,University of Evora | Caldeira A.T.,Evora Chemistry Center
Analytical and Bioanalytical Chemistry | Year: 2014

The knowledge about the microbial communities present in mural paintings is of utmost importance to develop effective conservation and mitigation strategies. The present paper describes a methodological approach for the detailed characterisation of microorganisms thriving in mural paintings by combining culture-dependent methods that allow the identification of microorganisms capable of growing in the laboratory conditions and to obtain high cell densities for further studies, and culture independent methods, such as denaturing gradient gel electrophoresis (DGGE) and pyrosequencing. The coupled use of culture-dependent methods and DGGE does not give enough information to investigate the diversity and abundance of microorganisms present in wall paintings. Pyrosequencing, a novel molecular technique, used here for the first time in this area of research, allowed the identification of a large number of microorganisms, confirming some already identified by the cultivation-dependent methods such as fungi of the genera Penicillium and Cladosporium, but also providing a great contribution in the identification of several genera and species, not previously identified in these artworks, giving also a detailed overview of contaminants which was not possible with the other approaches. The results obtained on several mural painting samples show a strong relationship between the most deteriorated areas of the paintings and higher microbial contamination. © 2013 Springer-Verlag Berlin Heidelberg. Source


Bottaini C.,University of Evora | Mirao J.,University of Evora | Mirao J.,Evora Geophysics Center | Figuereido M.,Archaeologist Monte da Capelinha | And 5 more authors.
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2015

Energy dispersive X-ray fluorescence (EDXRF) is a well-known technique for non-destructive and in situ analysis of archaeological artifacts both in terms of the qualitative and quantitative elemental composition because of its rapidity and non-destructiveness. In this study EDXRF and realistic Monte Carlo simulation using the X-ray Monte Carlo (XRMC) code package have been combined to characterize a Cu-based bowl from the Iron Age burial from Fareleira 3 (Southern Portugal). The artifact displays a multilayered structure made up of three distinct layers: a) alloy substrate; b) green oxidized corrosion patina; and c) brownish carbonate soil-derived crust. To assess the reliability of Monte Carlo simulation in reproducing the composition of the bulk metal of the objects without recurring to potentially damaging patina's and crust's removal, portable EDXRF analysis was performed on cleaned and patina/crust coated areas of the artifact. Patina has been characterized by micro X-ray Diffractometry (μXRD) and Back-Scattered Scanning Electron Microscopy + Energy Dispersive Spectroscopy (BSEM + EDS). Results indicate that the EDXRF/Monte Carlo protocol is well suited when a two-layered model is considered, whereas in areas where the patina + crust surface coating is too thick, X-rays from the alloy substrate are not able to exit the sample. © 2014 Published by Elsevier B.V. Source


Manhita A.,Hercules Laboratory | Manhita A.,Evora Chemistry Center | Ferreira V.,University of Evora | Vargas H.,Institute of Museums and Conservation | And 10 more authors.
Microchemical Journal | Year: 2011

Wool samples were dyed with madder and alum, copper, and iron salts at different concentration by pre-mordanting (MD) and simultaneous mordanting (M + D) procedures. Samples were artificially aged to identify the influence of the mordant on the madder chromophores photodegradation. A set of analytical techniques was used for complete characterisation of the dyed fibres before and after light exposure, which included colour and chromophore analysis (colourimetry and LC-ESI-MS/MS analysis), determination of mordant ions amounts in the fibres (FAAS and ICP-OES analysis), morphological characterisation of the fibres and punctual chemical analysis (SEM-EDS studies).Fibre colour hue was found to be dependent on the mordant ion nature, mordant bath concentration and dyeing procedure. Mordant ion quantification showed that the uptake of metal ion by the fibres is relatively small, with the Cu ion presenting the highest affinity for the fibre. MD method yields fibres with higher amounts of metal ions and larger chromophore chromatographic peak areas corresponding, in general, to stronger colour hues. Photodegradation was more severe in alum mordant samples and in the first 480. h of light exposure. Chromophore degradation rates are unequal and dependent on the mordant nature, contributing for colour changes observed after light exposure. © 2010 Elsevier B.V. Source


Barrocas Dias C.,Hercules Laboratory | Barrocas Dias C.,Evora Chemistry Center | Barrocas Dias C.,University of Evora | Miranda M.,University of Evora | And 13 more authors.
Journal of Chemical Education | Year: 2013

Onion skins (Allium cepa L.) and hydrated potassium aluminum sulfate were used to dye wool samples. The main chromophores associated with this natural dye source, quercetin and quercetin-4′-O-glucoside, were identified in the dye bath and in wool extracts by high-pressure liquid chromatography (HPLC) equipped with a diode array detector (DAD) with the help of standards. Two procedures were used to extract dye molecules from dyed wool prior to HPLC-DAD qualitative analysis and the analytical methodology used was discussed in terms of the analysis of historical textile pieces dyed with natural sources. © 2013 The American Chemical Society and Division of Chemical Education, Inc. Source

Discover hidden collaborations