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Author  |
Monico, L.; Janssens, K.; Cotte, M.; Romani, A.; Sorace, L.; Grazia, C.; Brunetti, B.G.; Miliani, C. |
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Title |
Synchrotron-based X-ray spectromicroscopy and electron paramagnetic resonance spectroscopy to investigate the redox properties of lead chromate pigments under the effect of visible light |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Journal of analytical atomic spectrometry |
Abbreviated Journal |
J Anal Atom Spectrom |
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Volume |
30 |
Issue |
7 |
Pages |
1500-1510 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Light-induced redox processes have been established as the cause of the chromatic alterations of a number of artists' pigments used from the 15th to the 20th century. Despite the fact that a general comprehension of the mechanisms has been provided through the characterization of photo-degraded compounds, both exhaustive information on the wavelength-dependence of the alteration process of the pigments and experimental evidence in how visible light may influence the formation pathways of specific secondary compounds are still lacking. Establishing an analytical protocol for the study of wavelength-dependence of pigments on photo-redox pathways is relevant for the safe illumination of paintings, especially in view of the possible use of spectrally tunable light sources such as white light emitting diodes (WLEDs). In this work, we propose an integrated approach based on a combination of diffuse reflectance UV-visible, synchrotron radiation (SR)-based micro X-ray fluorescence (m-XRF)/X-ray absorption near edge structure (m-XANES) and electron paramagnetic resonance (EPR) spectroscopies to study the photo-redox process of Cr(VI) -> Cr(III) for lead chromate yellows (PbCr1-xSxO4, 0 <= x <= 0.8) under exposure to different monochromatic light. In view of the thin (3-5 mm) alteration layer that is formed at the paint surface after light exposure, SR-based Cr K-edge mu-XANES/mu-XRF analysis was employed to obtain information on the abundance, nature and distribution of the alteration of Cr(III)-compounds at the micrometricscale level. On the other hand, EPR spectroscopy was used as a complementary tool to the SR-based X-ray methods due to its sensitivity for revealing species containing one or more unpaired electrons and for distinguishing different coordination geometries of paramagnetic centers, such as Cr(V)-species. Semi-quantitative indications about the darkening of the paint surface were obtained by UV-Vis spectroscopy. An abundance of reduced Cr down to around 50% was detected at the aged surface of chrome yellow paints. The reduction process was favored not only by wavelengths shorter than 460 nm (i.e., where the pigment shows its maximum absorption) but also by light in the 490-530 nm range. The first evidence of the presence of Cr(V)-intermediates in the Cr(VI) -> Cr(III) reduction reaction allowed the risks of inducing photo-degradation of the 490-530 nm wavelength range to be explained. |
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Wos |
000356971900004 |
Publication Date |
2015-04-15 |
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Edition |
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ISSN |
0267-9477 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.379 |
Times cited |
17 |
Open Access |
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Notes |
; This research was supported by the Italian projects PRIN-(SICH) and PON- (ITACHA) and by Belgian Science Policy project S2-ART (BELSPO S4DA), the GOA “SOLARPAINT” (Research Fund Antwerp University, Belgium) and FWO (Brussels, Belgium) projects no. G.0C12.13, G.0704.08 and G.01769.09. ESRF is acknowledged for the grants received (experiments HG18 and HG26). L.S. and L.M. acknowledge the financial support of Ente-CRF and CNR-Short Term Mobility Programme 2013, respectively. ; |
Approved |
Most recent IF: 3.379; 2015 IF: 3.466 |
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Call Number |
UA @ admin @ c:irua:127059 |
Serial |
5862 |
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Author |
Monico, L.; Janssens, K.; Cotte, M.; Sorace, L.; Vanmeert, F.; Brunetti, B.G.; Miliani, C. |
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Title |
Chromium speciation methods and infrared spectroscopy for studying the chemical reactivity of lead chromate-based pigments in oil medium |
Type |
A1 Journal article |
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Year |
2016 |
Publication |
Microchemical journal
T2 – TECHNART Conference, APR 27-30, 2015, Catania, ITALY |
Abbreviated Journal |
Microchem J |
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Volume |
124 |
Issue |
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Pages |
272-282 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Environmental factors, such as light, humidity and temperature are triggering agents for the alteration of organic and/or inorganic constituents of oil paintings. The oxidation of the organic material is favored by increasing of relative humidity and temperature, whereas processes involving changes of the oxidation states of a number of inorganic pigments (e.g., vermilion, cadmium yellows, zinc yellows, chrome yellows) are mainly activated by light-exposure. In view of the optimization of the long-term conservation and restoration strategies of paintings it is of relevant interest to establish the consequences of thermal parameters (temperature and relative humidity) on the chemical/photochemical-reactivity and the nature of the alteration products of light sensitive-pigments in oil medium. To this aim here we propose a multi-method analytical approach based on the combination of diffuse reflectance UV-Vis, FTIR, synchrotron radiation (SR)-based micro X-ray fluorescence (mu-XRF)/micro-X-ray absorption neat edge structure ()CANES) and electron paramagnetic resonance (EPR) spectroscopies for studying the effects of different relative humidity conditions before and after light exposure on the reactivity of a series of lead chromate-based pigments [such as PbCrO4 center dot PbO (monoclinic), PbCrO4 (monoclinic) and PbCr0.2S0.8O4 (orthorhombic)] in an oil medium. The investigation of paint models was also compared to that of a late 19th century historical orthorhombic PbCr0.4S0.6O4 oil paint. Diffuse reflectance UV-Vis and FTIR spectroscopies were used to obtain information associated with chromatic changes and the formation of organo-metal degradation products at the paint surface. SR-based Cr K-edge mu-XANES/mu-XRF mapping analysis and EPR spectroscopy were employed in a complementary fashion to determine the amount, nature and distribution of Cr(III) and Cr(V)-based alteration compounds within the paints with micrometric spatial resolution. Under the employed thermal aging conditions, lead(II)-carboxylates and reduced Cr-compounds (in abundance of up to about 35% at the surface) have been identified in the lead chromate-based paints. The tendency of chromates to become reduced increased with increasing moisture levels and was favored for the orthorhombic PbCr0.2S0.8O4 compounds. The redox process gave rise to the formation of Cr(V)-species in relative amount much higher than that was formed in the equivalent paint which was exposed only to light. After light-exposure of the thermally aged paints, compounds ascribable to the oxidation of the organic binder were detected for all the types of pigments. Nevertheless, the previous thermal treatment increased the tendency toward photo-reduction of only the PbCr0.2S0.8O4 pigment. For this light-sensitive compound, the thickness variation of the reduced Cr-rich (ca. 70%) photo-alteration layer with moisture levels could be ascribed to a surface passivation phenomenon that had already occurred before photochemical aging. (C) 2015 Elsevier B.V. All rights reserved. |
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Wos |
000367755600042 |
Publication Date |
2015-09-12 |
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ISSN |
0026-265x; 0026-265x |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.034 |
Times cited |
23 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.034 |
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Call Number |
UA @ admin @ c:irua:131099 |
Serial |
5519 |
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Author |
Monico, L.; Janssens, K.; Hendriks, E.; Brunetti, B.G.; Miliani, C. |
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Title |
Raman study of different crystalline forms of PbCrO4 and PbCr1-xSxO4 solid solutions for the noninvasive identification of chrome yellows in paintings : a focus on works by Vincent van Gogh |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Journal of Raman spectroscopy |
Abbreviated Journal |
J Raman Spectrosc |
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Volume |
45 |
Issue |
11-12 |
Pages |
1034-1045 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Chrome yellows, a class of pigments frequently used by painters of the Impressionism and Post-impressionism period, are known for their different chemical stability; the latter depends on the chemical composition (PbCrO4, PbCr1-xSxO4) and crystalline structure (monoclinic or orthorhombic) of the material. The possibility to distinguish among different forms of this pigment is therefore relevant in order to extend knowledge on the corresponding degradation process that is observed on several original paintings. For this purpose, three paintings conserved at the Van Gogh Museum (Amsterdam) were analyzed using noninvasive Raman spectroscopy, while equivalent investigations employing bench-top instrumentation were performed to obtain information from micro-samples originating from these works of art. In each painting, the chrome yellow was identified either as monoclinic PbCrO4 or in the form of monoclinic PbCr1-xSxO4 (x<0.25) or S-rich orthorhombic PbCr1-xSxO4 (x similar to 0.5). Our ability to make this fairly subtle distinction is based on a Raman study of several oil paint model samples made up of monoclinic and/or orthorhombic crystalline forms of PbCrO4 and PbCr1-xSxO4 (0.1x0.8). These paints were studied using several excitation wavelengths (namely 785.0, 532.0, 514.5, and 488nm). Because of the absence of the resonance Raman effect, which strongly enhances the chromate symmetric stretching band, and the absence of any laser-induced photodecomposition, it is advantageous to acquire data at 785.0nm. The band-shape and the position of the chromate bending modes proved to be more sensitive to the solid solution composition and crystalline structure than the stretching modes and can be used as distinctive spectral markers to discriminate among the different chrome yellow forms that are present. Copyright (c) 2014 John Wiley & Sons, Ltd. |
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Wos |
000346912700008 |
Publication Date |
2014-07-17 |
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ISSN |
0377-0486 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.969 |
Times cited |
34 |
Open Access |
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Notes |
; This research was supported by Interuniversity Attraction Poles Programme – Belgian Science Policy (S2-ART project S4DA) and also presents results from GOA 'XANES meets ELNES' (Research Fund University of Antwerp, Belgium), FWO (Brussels, Belgium) projects no. G.0704.08 and G.01769.09. Support from the Italian projects PRIN (SICH Sustainability in Cultural Heritage: from diagnosis to the development of innovative system for consolidation, cleaning and protection) and PON (ITACHA Italian advanced technologies for cultural heritage applications) is also acknowledged. The analysis of the paintings Sunflowers gone to seed, Bank of the Seine, and Portrait of Gauguin was performed within the mobile laboratory access activity of the FP7 programme CHARISMA supported by EC (Grant Agreement 228330). LM acknowledges the Italian National Research Council (CNR) for the financial support in the framework of the Short Term Mobility Programme 2013. Thanks are expressed to Muriel Geldof, Cultural Heritage Agency of The Netherlands, for selecting and sharing the information on the cross-sections and to the staff of the Van Gogh Museum for the agreeable cooperation. ; |
Approved |
Most recent IF: 2.969; 2014 IF: 2.671 |
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Call Number |
UA @ admin @ c:irua:122841 |
Serial |
5798 |
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Author |
Monico, L.; Janssens, K.; Hendriks, E.; Vanmeert, F.; van der Snickt, G.; Cotte, M.; Falkenberg, G.; Brunetti, B.G.; Miliani, C. |
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Title |
Evidence for degradation of the chrome yellows in Van Gogh's sunflowers : a study using noninvasive in situ methods and synchrotron-radiation-based x-ray techniques |
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A1 Journal article |
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Year |
2015 |
Publication |
Angewandte Chemie: international edition in English |
Abbreviated Journal |
Angew Chem Int Edit |
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Volume |
54 |
Issue |
47 |
Pages |
13923-13927 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
This paper presents firm evidence for the chemical alteration of chrome yellow pigments in Van Gogh's Sunflowers (Van Gogh Museum, Amsterdam). Noninvasive in situ spectroscopic analysis at several spots on the painting, combined with synchrotron-radiation-based X-ray investigations of two microsamples, revealed the presence of different types of chrome yellow used by Van Gogh, including the lightfast PbCrO4 and the sulfur-rich PbCr1-xSxO4 (x approximate to 0.5) variety that is known for its high propensity to undergo photoinduced reduction. The products of this degradation process, i.e., Cr-III compounds, were found at the interface between the paint and the varnish. Selected locations of the painting with the highest risk of color modification by chemical deterioration of chrome yellow are identified, thus calling for careful monitoring in the future. |
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Wos |
000367722500009 |
Publication Date |
2015-10-20 |
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ISSN |
1433-7851; 0570-0833 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
11.994 |
Times cited |
24 |
Open Access |
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Notes |
; We acknowledge financial support from the Italian MIUR project SICH-PRIN (2010329WPF_001) and BELSPO (Brussels) Project S2-ART (SD04A), GOA “SOLARPAINT” (Research Fund Antwerp University, BOF-2015), and FWO (Brussels) projects G.0C12.13, G.0704.08, G.01769.09. We thank ESRF (EC-1051, HG-26) and DESY (I-20120312 EC) for beamtime grants received. Noninvasive analysis of Sunflowers were supported by the EU FP7 programme CHARISMA (Grant 228330) and the Fund Inbev-Baillet Latour (Brussels). L.M. acknowledges financial support from the CNR Short Term Mobility Programme-2013. We thank Muriel Geldof, Luc Megens, Suzan de Groot (The Netherlands Cultural Heritage Agency, RCE), Chiara Grazia, David Buti (CNR-ISTM and SMAArt Centre), and the staff of the Van Gogh Museum for their collaboration. ; |
Approved |
Most recent IF: 11.994; 2015 IF: 11.261 |
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Call Number |
UA @ admin @ c:irua:131110 |
Serial |
5617 |
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Author |
Monico, L.; Janssens, K.; Miliani, C.; van der Snickt, G.; Brunetti, B.G.; Guidi, M.C.; Radepont, M.; Cotte, M. |
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Title |
Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods : 4 : artificial aging of model samples of co-precipitates of lead chromate and lead sulfate |
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A1 Journal article |
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Year |
2013 |
Publication |
Analytical chemistry |
Abbreviated Journal |
Anal Chem |
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Volume |
85 |
Issue |
2 |
Pages |
860-867 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Previous investigations about the darkening of chrome yellow pigments revealed that this form of alteration is attributable to a reduction of the original Cr(VI) to Cr(III), and that the presence of sulfur-containing compounds, most often sulfates, plays a key role during this process. We recently demonstrated that different crystal forms of chrome yellow pigments (PbCrO4 and PbCr1xSxO4) are present in paintings by Vincent van Gogh. In the present work, we show how both the chemical composition and the crystalline structure of lead chromate-based pigments influence their stability. For this purpose, oil model samples made with in-house synthesized powders of PbCrO4 and PbCr1xSxO4 were artificially aged and characterized. We observed a profound darkening only for those paint models made with PbCr1xSxO4, rich in SO42 (x ≥ 0.4), and orthorhombic phases (>30 wt %). Cr and S K-edge micro X-ray absorption near edge structure investigations revealed in an unequivocal manner the formation of up to about 60% of Cr(III)-species in the outer layer of the most altered samples; conversely, independent of the paint models chemical composition, no change in the S-oxidation state was observed. Analyses employing UVvisible diffuse reflectance and Fourier transform infrared spectroscopy were performed on unaged and aged model samples in order to obtain additional information on the physicochemical changes induced by the aging treatment. |
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Wos |
000313668400032 |
Publication Date |
2012-10-10 |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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ISSN |
0003-2700; 5206-882x |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.32 |
Times cited |
49 |
Open Access |
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Notes |
; This research was supported by grants from ESRF (experiment EC-799), the Interuniversity Attraction Poles Programme-Belgian Science Policy (IUAP VI/16), and the BELSPO-SDD S2-ART (SD/RI/04) project. The text also presents results from GOA “XANES meets ELNES” (Research Fund University of Antwerp, Belgium) and FWO (Brussels, Belgium) projects G.0704.08 and G.01769.09. The EU FP7 programme CHARISMA (Grant Agreement 228330) and MIUR (PRIN08, Materiali e sistemi innovativi per la conservazione dell'arte contemporanea 2008 FFXXN9) are also acknowledged. ; |
Approved |
Most recent IF: 6.32; 2013 IF: 5.825 |
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Call Number |
UA @ admin @ c:irua:110471 |
Serial |
5569 |
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Author |
Monico, L.; Janssens, K.; Vanmeert, F.; Cotte, M.; Brunetti, B.G.; van der Snickt, G.; Leeuwestein, M.; Plisson, J.S.; Menu, M.; Miliani, C. |
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Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods : part 5 : effects of nonoriginal surface coatings into the nature and distribution of chromium and sulfur species in chrome yellow paints |
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A1 Journal article |
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Year |
2014 |
Publication |
Analytical chemistry |
Abbreviated Journal |
Anal Chem |
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Volume |
86 |
Issue |
21 |
Pages |
10804-10811 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
The darkening of lead chromate yellow pigments, caused by a reduction of the chromate ions to Cr(III) compounds, is known to affect the appearance of several paintings by Vincent van Gogh. In previous papers of this series, we demonstrated that the darkening is activated by light and depends on the chemical composition and crystalline structure of the pigments. In this work, the results of Part 2 are extended and complemented with a new study aimed at deepening the knowledge of the nature and distribution of Cr and S species at the interface between the chrome yellow paint and the nonoriginal coating layer. For this purpose, three microsamples from two varnished paintings by Van Gogh and a waxed low relief by Gauguin (all originally uncoated) have been examined. Because nonoriginal coatings are often present in artwork by Van Gogh and contemporaries, the understanding of whether or not their application has influenced the morphological and/or physicochemical properties of the chrome yellow paint underneath is relevant in view of the conservation of these masterpieces. In all the samples studied, microscopic X-ray fluorescence (mu-XRF) and X-ray absorption near edge structure (mu-XANES) investigations showed that Cr(III)-based alteration products are present in the form of grains inside the coating (generally enriched of S species) and also homogeneously widespread at the paint surface. The distribution of Cr(III) species may be explained by the mechanical friction caused by the coating application by brush that picked up and redistributed the superficial Cr compounds, likely already present in the reduced state as result of the photodegradation process. The analysis of the XANES profiles allowed us to obtain new insights into the nature of the Cr(III) alteration products, that were identified as sulfate-, oxide-, organo-metal-, and chloride-based compounds. Building upon the knowledge acquired through the examination of original paint samples and from the investigation of aged model paints in the last Part 4 paper, in this study we aim to characterize a possible relation between the chemical composition of the coating and the chrome yellow degradation pathways by studying photochemically aged model samples covered with a dammar varnish contaminated with sulfide and sulfate salts. Cr speciation results did not show any evidence of the active role of the varnish and added S species on the reduction process of chrome yellows. |
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000344510200043 |
Publication Date |
2014-10-10 |
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0003-2700; 5206-882x |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.32 |
Times cited |
25 |
Open Access |
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Notes |
; This research was supported by the Italian projects PRIN (SICH) and PON (ITACHA). The text also presents results from Interuniversity Attraction Poles Programme Belgian Science Policy (S2-ART project S4DA), GOA “XANES meets ELNES” (Research Fund University of Antwerp, Belgium) and FWO (Brussels, Belgium) projects no. G.0704.08 and G.01769.09. ESRF is acknowledged for the grants received (experiments EC-799 and EC-1051). L.M. acknowledges the CNR for the financial support received in the framework of the Short Term Mobility Programme 2013. Thanks are expressed to Ella Hendriks (Van Gogh Museum, Amsterdam) and Muriel Geldof (Cultural Heritage Agency of The Netherlands) for selecting and sharing the information on the cross-section taken from Bank of the Seine. All the staff of the Van Gogh Museum, the Kroller-Muller Museum, and the Musee d'Orsay are acknowledged for the agreeable cooperation. ; |
Approved |
Most recent IF: 6.32; 2014 IF: 5.636 |
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Call Number |
UA @ admin @ c:irua:122100 |
Serial |
5570 |
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Author |
Monico, L.; Rosi, F.; Miliani, C.; Daveri, A.; Brunetti, B.G. |
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Title |
Non-invasive identification of metal-oxalate complexes on polychrome artwork surfaces by reflection mid-infrared spectroscopy |
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A1 Journal article |
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Year |
2013 |
Publication |
Spectrochimica acta: part A: molecular and biomolecular spectroscopy |
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Volume |
116 |
Issue |
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Pages |
270-280 |
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A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
In this work a reflection mid-infrared spectroscopy study of twelve metal-oxalate complexes, of interest in art conservation science as alteration compounds, was performed. Spectra of the reference materials highlighted the presence of derivative-like and/or inverted features for the fundamental vibrational modes as result of the main contribution from the surface component of the reflected light. In order to provide insights in the interpretation of theses spectral distortions, reflection spectra were compared with conventional transmission ones. The Kramers-Kronig (KK) algorithm, employed to correct for the surface reflection distortions, worked properly only for the derivative-like bands. Therefore, to pay attention to the use of this algorithm when interpreting the reflection spectra is recommended. The outcome of this investigation was exploited to discriminate among different oxalates on thirteen polychrome art-works analyzed in situ by reflection mid-infrared spectroscopy. The visualization of the v(s)(CO) modes (1400-1200 cm(-1)) and low wavenumber bands (below 900 cm(-1)) in the raw reflection profiles allowed Ca, Cu and Zn oxalates to be identified. Further information about the speciation of different hydration forms of calcium oxalates were obtained by using the KK transform. The work proves reflection mid-infrared spectroscopy to be a reliable and sensitive spectro-analytical method for identifying and mapping different metal-oxalate alteration compounds on the surface of artworks, thus providing conservation scientists with a non-invasive tool to obtain information on the state of conservation and causes of alteration of artworks. (C) 2013 Elsevier B.V. All rights reserved. |
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Wos |
000326207900035 |
Publication Date |
2013-07-12 |
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Edition |
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ISSN |
1386-1425 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Times cited |
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no |
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Call Number |
UA @ admin @ c:irua:112701 |
Serial |
8313 |
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Author |
Monico, L.; Sorace, L.; Cotte, M.; de Nolf, W.; Janssens, K.; Romani, A.; Miliani, C. |
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Title |
Disclosing the binding medium effects and the pigment solubility in the (photo)reduction process of chrome yellows (PbCrO4/PbCr1-xSxO4) |
Type |
A1 Journal article |
| |
Year |
2019 |
Publication |
ACS Omega |
Abbreviated Journal |
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| |
Volume |
4 |
Issue |
4 |
Pages |
6607-6619 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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| |
Abstract |
The darkening due to chemical alteration of chrome yellows (PbCrO4/PbCr1-xSxO4) is a phenomenon threatening a large number of 19th-20th century paintings, including the Amsterdam Sunflowers by Vincent van Gogh. Our earlier studies have proven that the alteration is due to a Cr(VI) -> Cr(III) reduction with Cr(V)-species that are formed as long-lived intermediates and that bCr(1-x)S(x)O(4) (0 < x <= 0.8) types undergo reduction more readily than monoclinic, S-free, PbCrO4. In this context, there is still lack of knowledge about the effects of the chemical properties of the binding medium (i.e., chemical composition and drying process) and the solubility of chrome yellows on the overall reduction pathways. Here, we study a series of naturally and photochemically aged mock-up paints prepared by mixing chrome yellow powders (PbCrO4/PbCr0.2S0.8O4) with either linseed oil or a water-based acrylic emulsion as the binding medium. Equivalent paints made up of the highly soluble K2CrO4 were also investigated and used as benchmarks to provide a more in-depth understanding of the influence of the solubility on the chromate reduction pathways in the two different binders. A combination of synchrotron radiation-based Cr K-edge X-ray absorption near edge structure (XANES), electron paramagnetic resonance (EPR), and UV-Visible spectroscopy measurements shows that: (1) the Cr(VI) reduction results from the interaction between the pigment and the binder; (2) the process is more significant in oil, giving rise to Cr(V)- and Cr(III)-species as well as oxidized organic compounds; (3) the lightfastness of the chrome yellow pigment is enhanced in the acrylic binder; and (4) the tendency toward chromium reduction increases with increasing solubility of the pigment. Based on our findings, we propose a scheme for the mechanism of the (photo)reduction process of chrome yellows in the oil and acrylic binder. Overall, our results provide new insights into the factors driving the degradation of lead chromate-based paints in artworks and contribute to the development of strategies for preserving them over time. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000466552500057 |
Publication Date |
2019-04-10 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
2470-1343 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
|
Times cited |
4 |
Open Access |
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| |
Notes |
; The research was financially supported by the European research project IPERION-CH, funded by the European Commission, H2020-INFRAIA-2014-2015 (grant agreement n. 654028), and by the project AMIS, within the program Dipartimenti di Eccellenza 2018-2022, funded by MIUR and University of Perugia. The University of Perugia is also acknowledged for financial support under the program “Ricerca di Base 2017”. L.S. acknowledges the financial support of Ente CRF. For the beamtime grants received, we thank the ESRF (experiment no. HG64 and in-house beamtimes). ; |
Approved |
Most recent IF: NA |
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| |
Call Number |
UA @ admin @ c:irua:160416 |
Serial |
5577 |
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| Permanent link to this record |
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| |
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Author |
Monico, L.; van der Snickt, G.; Janssens, K.; de Nolf, W.; Miliani, C.; Dik, J.; Radepont, M.; Hendriks, E.; Geldof, M.; Cotte, M. |
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| |
Title |
Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods : 2 : original paint layer samples |
Type |
A1 Journal article |
| |
Year |
2011 |
Publication |
Analytical chemistry |
Abbreviated Journal |
Anal Chem |
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| |
Volume |
83 |
Issue |
4 |
Pages |
1224-1231 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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| |
Abstract |
The darkening of the original yellow areas painted with the chrome yellow pigment (PbCrO4, PbCrO4·xPbSO4, or PbCrO4·xPbO) is a phenomenon widely observed on several paintings by Vincent van Gogh, such as the famous different versions of Sunflowers. During our previous investigations on artificially aged model samples of lead chromate, we established for the first time that darkening of chrome yellow is caused by reduction of PbCrO4 to Cr2O3·2H2O (viridian green), likely accompanied by the presence of another Cr(III) compound, such as either Cr2(SO4)3·H2O or (CH3CO2)7Cr3(OH)2 [chromium(III) acetate hydroxide]. In the second part of this work, in order to demonstrate that this reduction phenomenon effectively takes place in real paintings, we study original paint samples from two paintings of V. van Gogh. As with the model samples, in view of the thin superficial alteration layers that are present, high lateral resolution spectroscopic methods that make use of synchrotron radiation (SR), such as microscopic X-ray absorption near edge (μ-XANES) and X-ray fluorescence spectrometry (μ-XRF) were employed. Additionally, μ-Raman and mid-FTIR analyses were carried out to completely characterize the samples. On both paint microsamples, the local presence of reduced Cr was demonstrated by means of μ-XANES point measurements. The presence of Cr(III) was revealed in specific areas, in some cases correlated to the presence of Ba(sulfate) and/or to that of aluminum silicate compounds. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000287176900012 |
Publication Date |
2011-02-14 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
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| |
ISSN |
0003-2700; 5206-882x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
6.32 |
Times cited |
84 |
Open Access |
|
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| |
Notes |
; This research was funded by grants from ESRF (experiment EC-504) and by HASYLAB (experiments 11-20080130 EC and 11-20070157 EC) and was supported by the Interuniversity Attraction Poles Programme-Belgian Science Policy (IUAP VI/16). The text also presents results of GOA “XANES meets ELNES” (Research Fund University of Antwerp, Belgium) and from FWO (Brussels, Belgium) project nos. G.0103.04, G.0689.06, and G.0704.08. The staff of the Van Gogh Museum, Amsterdam, is acknowledged for their agreeable cooperation and for the authorization to publish the images of the paintings in this article. L.M. was financially supported by the Erasmus Placement in the framework of Lifelong Learning Programme (A.Y. 2009-2010). The EU Community's FP7 Research Infrastructures program under the CHARISMA Project (Grant Agreement 228330) is also acknowledged. ; |
Approved |
Most recent IF: 6.32; 2011 IF: 5.856 |
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| |
Call Number |
UA @ admin @ c:irua:88795 |
Serial |
5571 |
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| Permanent link to this record |
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Author |
Monico, L.; van der Snickt, G.; Janssens, K.; de Nolf, W.; Miliani, C.; Verbeeck, J.; Tian, H.; Tan, H.; Dik, J.; Radepont, M.; Cotte, M. |
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| |
Title |
Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods : 1 : artificially aged model samples |
Type |
A1 Journal article |
| |
Year |
2011 |
Publication |
Analytical chemistry |
Abbreviated Journal |
Anal Chem |
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| |
Volume |
83 |
Issue |
4 |
Pages |
1214-1223 |
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| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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| |
Abstract |
On several paintings by artists of the end of the 19th century and the beginning of the 20th Century a darkening of the original yellow areas, painted with the chrome yellow pigment (PbCrO4, PbCrO4·xPbSO4, or PbCrO4·xPbO) is observed. The most famous of these are the various Sunflowers paintings Vincent van Gogh made during his career. In the first part of this work, we attempt to elucidate the degradation process of chrome yellow by studying artificially aged model samples. In view of the very thin (1−3 μm) alteration layers that are formed, high lateral resolution spectroscopic methods such as microscopic X-ray absorption near edge (μ-XANES), X-ray fluorescence spectrometry (μ-XRF), and electron energy loss spectrometry (EELS) were employed. Some of these use synchrotron radiation (SR). Additionally, microscopic SR X-ray diffraction (SR μ-XRD), μ-Raman, and mid-FTIR spectroscopy were employed to completely characterize the samples. The formation of Cr(III) compounds at the surface of the chrome yellow paint layers is particularly observed in one aged model sample taken from a historic paint tube (ca. 1914). About two-thirds of the chromium that is present at the surface has reduced from the hexavalent to the trivalent state. The EELS and μ-XANES spectra are consistent with the presence of Cr2O3·2H2O (viridian). Moreover, as demonstrated by μ-XANES, the presence of another Cr(III) compound, such as either Cr2(SO4)3·H2O or (CH3CO2)7Cr3(OH)2 [chromium(III) acetate hydroxide], is likely. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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Language |
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Wos |
000287176900011 |
Publication Date |
2011-02-14 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0003-2700;1520-6882; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.32 |
Times cited |
113 |
Open Access |
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Notes |
Iuap; Fwo |
Approved |
Most recent IF: 6.32; 2011 IF: 5.856 |
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Call Number |
UA @ lucian @ c:irua:88794UA @ admin @ c:irua:88794 |
Serial |
632 |
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| Permanent link to this record |
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Author |
Morales-Yanez, F.; Trashin, S.; Hermy, M.; Sariego, I.; Polman, K.; Muyldermans, S.; De Wael, K. |
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Title |
Fast one-step ultrasensitive detection of toxocara canis antigens by a nanobody-based electrochemical magnetosensor |
Type |
A1 Journal article |
| |
Year |
2019 |
Publication |
Analytical chemistry |
Abbreviated Journal |
Anal Chem |
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Volume |
91 |
Issue |
18 |
Pages |
11582-11588 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Human toxocariasis (HT) is a cosmopolitan zoonotic disease caused by the migration of the larval stage of the roundworm Toxocara canis. Current HT diagnostic methods do not discriminate between active and past infections. Here, we present a method to quantify Toxocara excretory/secretory antigen, aiming to identify active cases of HT. High specificity is achieved by employing nanobodies (Nbs), single domain antigen binding fragments from camelid heavy chain-only antibodies. High sensitivity is obtained by the design of an electrochemical magnetosensor with an amperometric read-out. Reliable detection of TES antigen at 10 and 30 pg/mL level was demonstrated in phosphate buffered saline and serum, respectively. Moreover, the assay showed no cross-reactivity with other nematode antigens. To our knowledge, this is the most sensitive method to quantify the TES antigen so far. It also has great potential to develop point of care diagnostic systems in other conditions where high sensitivity and specificity are required. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000487156900016 |
Publication Date |
2019-08-20 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0003-2700; 5206-882x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.32 |
Times cited |
2 |
Open Access |
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Notes |
; This project was funded by the Fonds Wetenschappelijk Onderzoek-Vlaanderen (FWO-Flanders, Project G.0189.13N) and BOF UAntwerp. The authors acknowledge Prof. Pierre Dorny (Institute of Tropical Medicine Antwerp) and Dr. Beatrice Nickel (Swiss Institute of Tropical Medicine) for providing the antigens needed for the cross-reactivity experiments. ; |
Approved |
Most recent IF: 6.32 |
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Call Number |
UA @ admin @ c:irua:163784 |
Serial |
5621 |
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| Permanent link to this record |
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Author |
Morales-Yánez, F.; Trashin, S.; Sariego, I.; Roucher, C.; Paredis, L.; Chico, M.; De Wael, K.; Muyldermans, S.; Cooper, P.; Polman, K. |
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Title |
Electrochemical detection of Toxocara canis excretory-secretory antigens in children from rural communities in Esmeraldas Province, Ecuador : association between active infection and high eosinophilia |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Parasites & Vectors |
Abbreviated Journal |
Parasite Vector |
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Volume |
13 |
Issue |
1 |
Pages |
245-247 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Background The diagnosis of active Toxocara canis infections in humans is challenging. Larval stages of T. canis do not replicate in human tissues and disease may result from infection with a single T. canis larva. Recently, we developed a nanobody-based electrochemical magnetosensor assay with superior sensitivity to detect T. canis excretory-secretory (TES) antigens. Here, we evaluate the performance of the assay in children from an Ecuadorian birth cohort that followed children to five years of age. Methods Samples were selected based on the presence of peripheral blood eosinophilia and relative eosinophil counts. The samples were analyzed by the nanobody-based electrochemical magnetosensor assay, which utilizes a bivalent biotinylated nanobody as capturing agent on the surface of streptavidin pre-coated paramagnetic beads. Detection was performed by a different nanobody chemically labelled with horseradish peroxidase. Results Of 87 samples tested, 33 (38%) scored positive for TES antigen recognition by the electrochemical magnetosensor assay. The average concentration of TES antigen in serum was 2.1 ng/ml (SD = 1.1). The positive result in the electrochemical assay was associated with eosinophilia > 19% (P = 0.001). Parasitological data were available for 57 samples. There was no significant association between positivity by the electrochemical assay and the presence of other soil-transmitted helminth infections. Conclusions Our nanobody-based electrochemical assay provides highly sensitive quantification of TES antigens in serum and has potential as a valuable tool for the diagnosis of active human toxocariasis. |
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Place of Publication |
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Language |
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Wos |
000535618800003 |
Publication Date |
2020-05-12 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1756-3305 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.2 |
Times cited |
|
Open Access |
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Notes |
; This project was funded by the Fonds Wetenschappelijk Onderzoek-Vlaanderen (FWO-Flanders), project No. G.0189.13N. The ECUAVIDA cohort was funded by the Wellcome Trust (grant 072405/Z/03/Z and 088862/Z/09/Z). ; |
Approved |
Most recent IF: 3.2; 2020 IF: 3.08 |
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Call Number |
UA @ admin @ c:irua:168966 |
Serial |
6501 |
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Author |
Moro, G.; Barich, H.; Driesen, K.; Montiel, N.F.; Neven, L.; Mendonca, C.D.; Thiruvottriyur Shanmugam, S.; Daems, E.; De Wael, K. |
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Title |
Unlocking the full power of electrochemical fingerprinting for on-site sensing applications |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Analytical And Bioanalytical Chemistry |
Abbreviated Journal |
Anal Bioanal Chem |
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Volume |
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Issue |
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Pages |
1-14 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Electrochemical sensing for the semi-quantitative detection of biomarkers, drugs, environmental contaminants, food additives, etc. shows promising results in point-of-care diagnostics and on-site monitoring. More specifically, electrochemical fingerprint (EF)-based sensing strategies are considered an inviting approach for the on-site detection of low molecular weight molecules. The fast growth of electrochemical sensors requires defining the concept of direct electrochemical fingerprinting in sensing. The EF can be defined as the unique electrochemical signal or pattern, mostly recorded by voltammetric techniques, specific for a certain molecule that can be used for its quantitative or semi-quantitative identification in a given analytical context with specified circumstances. The performance of EF-based sensors can be enhanced by considering multiple features of the signal (i.e., oxidation or reduction patterns), in combination with statistical data analysis or sample pretreatments or by including electrode surface modifiers to enrich the EF. In this manuscript, some examples of EF-based sensors, strategies to improve their performances, and open challenges are discussed to unlock the full power of electrochemical fingerprinting for on-site sensing applications. |
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Corporate Author |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000523396300002 |
Publication Date |
2020-04-04 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1618-2642 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.3 |
Times cited |
3 |
Open Access |
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Notes |
; The presented review is the result of a concerted effort and fruitful discussions among enthusiastic, young, and (for the occasion) female researchers of the AXES research group, each of them with specific expertise and background, under the guidance of the corresponding author. The authors acknowledge FWO-Flanders, BOF-UA, IOF-UA, FAPESP and EU for funding. ; |
Approved |
Most recent IF: 4.3; 2020 IF: 3.431 |
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Call Number |
UA @ admin @ c:irua:168563 |
Serial |
6647 |
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Author |
Moro, G.; Bottari, F.; Liberi, S.; Covaceuszach, S.; Cassetta, A.; Angelini, A.; De Wael, K.; Moretto, L.M. |
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Title |
Covalent immobilization of delipidated human serum albumin on poly(pyrrole-2-carboxylic) acid film for the impedimetric detection of perfluorooctanoic acid |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Bioelectrochemistry |
Abbreviated Journal |
Bioelectrochemistry |
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Volume |
134 |
Issue |
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Pages |
107540 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
The immobilization of biomolecules at screen printed electrodes for biosensing applications is still an open challenge. To enrich the toolbox of bioelectrochemists, graphite screen printed electrodes (G-SPE) were modified with an electropolymerized film of pyrrole-2-carboxilic acid (Py-2-COOH), a pyrrole derivative rich in carboxylic acid functional groups. These functionalities are suitable for the covalent immobilization of biomolecular recognition layers. The electropolymerization was first optimized to obtain stable and conductive polymeric films, comparing two different electrolytes: sodium dodecyl sulphate (SDS) and sodium perchlorate. The G-SPE modified with Py-2-COOH in 0.1 M SDS solution showed the required properties and were further tested. A proof-of-concept study for the development of an impedimetric sensor for perfluorooctanoic acid (PFOA) was carried out using the delipidated human serum albumin (hSA) as bioreceptor. The data interpretation was supported by size exclusion chromatography and small-angle X-ray scattering (SEC-SAXS) analysis of the bioreceptor-target complex and the preliminary results suggest the possibility to further develop this biosensing strategy for toxicological and analytical studies. |
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Place of Publication |
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Wos |
000579727300004 |
Publication Date |
2020-04-27 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1567-5394 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5 |
Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: 5; 2020 IF: 3.346 |
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Call Number |
UA @ admin @ c:irua:172494 |
Serial |
6477 |
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| Permanent link to this record |
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Author |
Moro, G.; Bottari, F.; Sleegers, N.; Florea, A.; Cowen, T.; Moretto, L.M.; Piletsky, S.; De Wael, K. |
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Title |
Conductive imprinted polymers for the direct electrochemical detection of beta-lactam antibiotics: The case of cefquinome |
Type |
A1 Journal article |
| |
Year |
2019 |
Publication |
Sensors and actuators : B : chemical |
Abbreviated Journal |
Sensor Actuat B-Chem |
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Volume |
297 |
Issue |
297 |
Pages |
126786 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
A biomimetic sensor for cefquinome (CFQ) was designed at multi-walled carbon nanotubes modified graphite screen-printed electrodes (MWCNTs-G-SPEs) as a proof-of-concept for the creation of a sensors array for beta-lactam antibiotics detection in milk. The sensitive and selective detection of antibiotic residues in food and environment is a fundamental step in the elaboration of prevention strategies to fight the insurgence of antimicrobial resistance (AMR) as recommended by authorities around the world (EU, WHO, FDA). The detection strategy is based on the characteristic electrochemical fingerprint of the target antibiotic cefquinome. A conducive electropolymerized molecularly imprinted polymer (MIP) coupled with MWCNTs was found to be the optimal electrode modifier, able to provide an increased selectivity and sensitivity for CFQ detection. The design of CFQ-MIP was facilitated by the rational selection of the monomer, 4-aminobenzoic acid (4-ABA). The electropolymerization process of 4-ABA have not been fully elucidated yet; for this reason a thorough study and optimization of electropolymerization conditions was performed to obtain a conducive and stable poly(4-ABA) film. The modified electrodes were characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and cyclic voltammetry (CV). CFQ-MIP were synthesized at MWCNT-G-SPEs by electropolyrnerization in pH approximate to 1 (0.1 M sulphuric acid) with a monomer:template ratio of 5:1. Two different analytical protocols were tested (single and double step detection) to minimize unspecific adsorptions and improve the sensitivity. Under optimal conditions, the lowest CFQ concentration detectable by square wave voltammetry (SWV) at the modified sensor was 50 nM in 0.1 M phosphate buffer pH 2. |
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Corporate Author |
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Place of Publication |
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Language |
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Wos |
000478562700020 |
Publication Date |
2019-07-08 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0925-4005 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5.401 |
Times cited |
4 |
Open Access |
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Notes |
; This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No. 753223. This work was also supported by FWO. ; |
Approved |
Most recent IF: 5.401 |
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Call Number |
UA @ admin @ c:irua:161777 |
Serial |
5549 |
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| Permanent link to this record |
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Author |
Moro, G.; Bottari, F.; Van Loon, J.; Du Bois, E.; De Wael, K.; Moretto, L.M. |
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Title |
Disposable electrodes from waste materials and renewable sources for (bio) electroanalytical applications |
Type |
A1 Journal article |
| |
Year |
2019 |
Publication |
Biosensors and bioelectronics |
Abbreviated Journal |
Biosens Bioelectron |
|
| |
Volume |
146 |
Issue |
146 |
Pages |
111758 |
|
| |
Keywords |
A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Product development |
|
| |
Abstract |
The numerous advantages of disposable and screen-printed electrodes (SPEs) particularly in terms of portability, sensibility, sensitivity and low-cost led to the massive application of these electroanalytical devices. To limit the electronic waste and recover precious materials, new recycling processes were developed together with alternative SPEs fabrication procedures based on renewable, biocompatible sources or waste materials, such as paper, agricultural byproducts or spent batteries. The increased interest in the use of eco-friendly materials for electronics has given rise to a new generation of highly performing green modifiers. From paper based electrodes to disposable electrodes obtained from CD/DVD, in the last decades considerable efforts were devoted to reuse and recycle in the field of electrochemistry. Here an overview of recycled and recyclable disposable electrodes, sustainable electrode modifiers and alternative fabrication processes is proposed aiming to provide meaningful examples to redesign the world of disposable electrodes. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
|
Wos |
000497250600003 |
Publication Date |
2019-10-07 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0956-5663 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
7.78 |
Times cited |
2 |
Open Access |
|
|
| |
Notes |
; This research received funding from FWO and IOF (UAntwerpen). ; |
Approved |
Most recent IF: 7.78 |
|
| |
Call Number |
UA @ admin @ c:irua:164563 |
Serial |
5578 |
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| Permanent link to this record |
| |
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| |
|
Author |
Moro, G.; Cristofori, D.; Bottari, F.; Cattaruzza, E.; De Wael, K.; Moretto, L.M. |
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| |
Title |
Redesigning an electrochemical MIP sensor for PFOS : practicalities and pitfalls |
Type |
A1 Journal article |
| |
Year |
2019 |
Publication |
Sensors |
Abbreviated Journal |
Sensors-Basel |
|
| |
Volume |
19 |
Issue |
20 |
Pages |
4433 |
|
| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
|
| |
Abstract |
There is a growing interest in the technological transfer of highly performing electrochemical sensors within portable analytical devices for the in situ monitoring of environmental contaminants, such as perfluorooctanesulfonic acid (PFOS). In the redesign of biomimetic sensors, many parameters should be taken into account from the working conditions to the electrode surface roughness. A complete characterization of the surface modifiers can help to avoid time-consuming optimizations and better interpret the sensor responses. In the present study, a molecularly imprinted polymer electrochemical sensor (MIP) for PFOS optimized on gold disk electrodes was redesigned on commercial gold screen-printed electrodes. However, its performance investigated by differential pulse voltammetry was found to be poor. Before proceeding with further optimization, a morphological study of the bare and modified electrode surfaces was carried out by scanning electron microscopy-energy-dispersive X-ray spectrometry (SEM-EDS), atomic force microscopy (AFM) and profilometry revealing an heterogeneous distribution of the polymer strongly influenced by the electrode roughness. The high content of fluorine of the target-template molecule allowed to map the distribution of the molecularly imprinted polymer before the template removal and to define a characterization protocol. This case study shows the importance of a multi-analytical characterization approach and identify significant parameters to be considered in similar redesigning studies. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
|
Wos |
000497864700081 |
Publication Date |
2019-10-14 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
1424-8220 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
2.677 |
Times cited |
|
Open Access |
|
|
| |
Notes |
; ; |
Approved |
Most recent IF: 2.677 |
|
| |
Call Number |
UA @ admin @ c:irua:164686 |
Serial |
5808 |
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| Permanent link to this record |
| |
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| |
|
Author |
Moro, G.; De Wael, K.; Moretto, L.M. |
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| |
Title |
Challenges in the electrochemical (bio)sensing of non-electroactive food and environmental contaminants |
Type |
A1 Journal article |
| |
Year |
2019 |
Publication |
Current opinion in electrochemistry |
Abbreviated Journal |
|
|
| |
Volume |
16 |
Issue |
16 |
Pages |
57-65 |
|
| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
|
| |
Abstract |
The electrochemical detection of non-electroactive contaminants can be successfully faced via the use of indirect detection strategies. These strategies can provide sensitive and selective responses often coupled with portable and user-friendly analytical tools. Indirect detection strategies are usually based on the change in the signal of an electroactive probe, induced by the presence of the target molecule at a modified electrode. This critical review aims at addressing the developments in indirect electro-sensing strategies for non-electroactive contaminants in food and environmental analysis in the last years (2017-2019). Emphasis is given to the strategy design, the electrode modifiers used and the feasibility of technological transfer. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
|
Wos |
000485814400010 |
Publication Date |
2019-04-20 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
2451-9103; 2451-9111 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
|
Times cited |
4 |
Open Access |
|
|
| |
Notes |
; ; |
Approved |
Most recent IF: NA |
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| |
Call Number |
UA @ admin @ c:irua:159574 |
Serial |
5498 |
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| Permanent link to this record |
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| |
|
Author |
Moropoulou, A.; Bisbikou, K.; Torfs, K.; Van Grieken, R. |
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| |
Title |
Atmospheric deposition as decay factor for the Demeter sanctuary ruins in the industrial atmosphere of Eleusis, Greece |
Type |
A1 Journal article |
| |
Year |
1998 |
Publication |
Environmental technology |
Abbreviated Journal |
|
|
| |
Volume |
19 |
Issue |
|
Pages |
1039-1047 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
|
Wos |
000076784500007 |
Publication Date |
2008-06-20 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0959-3330 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
|
Times cited |
|
Open Access |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
UA @ admin @ c:irua:22776 |
Serial |
7523 |
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| Permanent link to this record |
| |
|
| |
|
Author |
Moropoulou, A.; Bisbikou, K.; Torfs, K.; Van Grieken, R. |
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| |
Title |
Risk analysis for the protection of cultural heritage from industrial pollution |
Type |
H3 Book chapter |
| |
Year |
1999 |
Publication |
|
Abbreviated Journal |
|
|
| |
Volume |
|
Issue |
|
Pages |
475-484
T2 - Structural studies, repairs and maint |
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| |
Keywords |
H3 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
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Publication Date |
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| |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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| |
Series Volume |
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Series Issue |
|
Edition |
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| |
ISSN |
|
ISBN |
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Additional Links |
UA library record |
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| |
Impact Factor |
|
Times cited |
|
Open Access |
|
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| |
Notes |
|
Approved |
no |
|
| |
Call Number |
UA @ admin @ c:irua:27598 |
Serial |
8483 |
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| Permanent link to this record |
| |
|
| |
|
Author |
Moropoulou, A.; Bisbikou, K.; Torfs, K.; Van Grieken, R.; Zezza, F.; Macri, F. |
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| |
Title |
Origin and growth of weathering crusts on ancient marbles in industrial atmosphere |
Type |
A1 Journal article |
| |
Year |
1998 |
Publication |
Atmospheric environment : an international journal |
Abbreviated Journal |
|
|
| |
Volume |
32 |
Issue |
|
Pages |
967-982 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
|
Place of Publication |
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Editor |
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| |
Language |
|
Wos |
000073710900002 |
Publication Date |
2002-07-26 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
1352-2310 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
|
Times cited |
|
Open Access |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
UA @ admin @ c:irua:20964 |
Serial |
8348 |
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| Permanent link to this record |
| |
|
| |
|
Author |
Moropoulou, A.; Bisbikou, K.; Van Grieken, R.; Torfs, K.; Polikreti, K. |
|
| |
Title |
Correlation between aerosols, deposits, and weathering crusts on ancient marbles |
Type |
A1 Journal article |
| |
Year |
2001 |
Publication |
Environmental technology |
Abbreviated Journal |
|
|
| |
Volume |
22 |
Issue |
|
Pages |
607-618 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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| |
Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
|
Wos |
000169968300001 |
Publication Date |
2008-06-20 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0959-3330 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
|
Times cited |
|
Open Access |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
UA @ admin @ c:irua:36081 |
Serial |
7734 |
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| Permanent link to this record |
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| |
|
Author |
Moropoulou, A.; Cakmak, A.; Labropoulos, K.C.; Van Grieken, R.; Torfs, K. |
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| |
Title |
Accelerated microstructural evolution of a calcium-silicate-hydrate (C-S-H) phase in pozzolanic pastes using fine siliceous sources: comparison with historic pozzolanic mortars |
Type |
A1 Journal article |
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Year |
2004 |
Publication |
Cement and concrete research |
Abbreviated Journal |
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| |
Volume |
34 |
Issue |
|
Pages |
1-6 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
|
Place of Publication |
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Editor |
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Language |
|
Wos |
000224016100001 |
Publication Date |
2003-06-20 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
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| |
ISSN |
0008-8846 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
|
Times cited |
|
Open Access |
|
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| |
Notes |
|
Approved |
no |
|
| |
Call Number |
UA @ admin @ c:irua:49510 |
Serial |
7411 |
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| Permanent link to this record |
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| |
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Author |
Moropoulou, A.; Koui, M.; Theoulakis, P.; Bakolas, A.; Roumpopoulos, K.; Michailidis, P.; Van Grieken, R.; Cardell-Fernandez, C. |
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| |
Title |
Microstructural criteria for the evaluation of stone susceptibility to sea-salt decay |
Type |
P3 Proceeding |
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Year |
2002 |
Publication |
|
Abbreviated Journal |
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| |
Volume |
|
Issue |
|
Pages |
|
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| |
Keywords |
P3 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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| |
Abstract |
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| |
Address |
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Corporate Author |
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Thesis |
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| |
Publisher |
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Place of Publication |
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Editor |
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| |
Language |
|
Wos |
|
Publication Date |
|
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| |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
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| |
ISSN |
|
ISBN |
|
Additional Links |
UA library record |
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| |
Impact Factor |
|
Times cited |
|
Open Access |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
UA @ admin @ c:irua:36681 |
Serial |
8249 |
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| Permanent link to this record |
| |
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| |
|
Author |
Mudronja, D.; Vanmeert, F.; Fazinic, S.; Janssens, K.; Tibljas, D.; Desnica, V. |
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| |
Title |
Protection of stone monuments using a brushing treatment with ammonium oxalate |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Coatings |
Abbreviated Journal |
Coatings |
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| |
Volume |
11 |
Issue |
4 |
Pages |
379 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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| |
Abstract |
Stone monuments and buildings are susceptible to weathering. Carbonate-based stones are especially vulnerable in acidic environments, whereas magmatic acidic stones are more susceptible to chemical weathering in basic environments. To slow down surface corrosion of limestone and marble artworks/buildings, protective coatings which inhibit calcite dissolution have been proposed. In this work, samples from two stone types with different porosity were treated with ammonium oxalate (AmOx) to create a protective layer of calcium oxalate (CaOx) using the previously developed brushing method. Two different synchrotron microscopy experiments were performed to determine its protective capability. X-ray powder diffraction (SR-mu-XRPD) in transmission geometry allowed visualization of the distributions of calcium carbonate and oxalates along the sample depths. In a second step, X-ray fluorescence (SR-mu-XRF) was used to check the efficiency/integrity of the protective surface coating layer. This was done by measuring the sulfur distribution on the stone surface after exposing the protected stones to sulfuric acid. XRPD showed the formation of a protective oxalate layer with a thickness of 5-15 mu m on the less porous stone, while a 20-30 mu m thick layer formed on the more porous stone. The XRF study showed that the optimal treatment time depends on the stone porosity. Increasing the treatment time from 1 to 3 h resulted in a decreased efficiency of the protective layer for the low porosity stone. We assume that this is due to the formation of vertical channels (cracks) in the protective layer. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
|
Wos |
000642940900001 |
Publication Date |
2021-03-25 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
2079-6412 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
2.175 |
Times cited |
|
Open Access |
OpenAccess |
|
| |
Notes |
|
Approved |
Most recent IF: 2.175 |
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| |
Call Number |
UA @ admin @ c:irua:178271 |
Serial |
8428 |
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| Permanent link to this record |
| |
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| |
|
Author |
Mudronja, D.; Vanmeert, F.; Hellemans, K.; Fazinic, S.; Janssens, K.; Tibljas, D.; Rogosic, M.; Jakovljevic, S. |
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| |
Title |
Efficiency of applying ammonium oxalate for protection of monumental limestone by poultice, immersion and brushing methods |
Type |
A1 Journal article |
| |
Year |
2013 |
Publication |
Applied physics A : materials science & processing |
Abbreviated Journal |
Appl Phys A-Mater |
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| |
Volume |
111 |
Issue |
1 |
Pages |
109-119 |
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| |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
|
| |
Abstract |
Samples of cretaceous limestone have been treated with three application methods (poultice, immersion and brushing) using different concentrations of ammonium oxalate solution (AmOx) and varying treatment time in order to test the efficiency of surface and in-depth formation of a protective layer of calcium oxalate (CaOx). Synchrotron-based microanalytical techniques (SR-mu XRD with 12.5 mu mx7.5 mu m (HxV) probe size, SR-mu FTIR with 10 mu mx10 mu m and 8 mu mx20 mu m probe sizes) and laboratory mu FTIR, XRD and SEM have been employed for analysis of the treated samples. Synchrotron-based techniques showed variations in the CaOx distribution along the surface on a micrometer scale. All treatments resulted in the development of a CaOx layer with a maximum thickness of approximately 40 mu m. Application by the brushing method with 10 1-min applications with 5-min breaks during one hour showed a development of the calcium oxalate layer equivalent to the poultice treatment taking 10 h. This treatment could be preferred for large marble or limestone surfaces where poultice usage is economically not feasible. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
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Wos |
000316075700014 |
Publication Date |
2012-10-29 |
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| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0947-8396 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
1.455 |
Times cited |
13 |
Open Access |
|
|
| |
Notes |
; This research was supported by the Interuniversity Attraction Poles Programme-Belgian Science Policy (IUAP VI/16). The text also presents results of GOA 'XANES meets ELNES' (Research Fund, University of Antwerp, Belgium) and from FWO (Brussels, Belgium) project nos. G.0704.08 and G.01769.09. The research leading to these results has received financial support by the Access to Research Infrastructures activity in the 7th Framework Programme of the EU (CHARISMA Grant Agreement No. 228330). ; |
Approved |
Most recent IF: 1.455; 2013 IF: 1.694 |
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| |
Call Number |
UA @ admin @ c:irua:108262 |
Serial |
5584 |
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| Permanent link to this record |
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| |
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Author |
Muhammad, S.; Wuyts, K.; De Wael, K.; Samson, R. |
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| |
Title |
Does leaf micro-morphology influence the recognition of particles on SEM images? |
Type |
A3 Journal article |
| |
Year |
2021 |
Publication |
International Journal of Environmental Pollution and Remediation |
Abbreviated Journal |
|
|
| |
Volume |
9 |
Issue |
|
Pages |
22-37 |
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| |
Keywords |
A3 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab) |
|
| |
Abstract |
Scanning electron microscopy (SEM) remains a popular approach to determine the shape, size, density and elemental composition of particles collected on leaf surfaces, but the effect of leaf micro-morphology on particle counts is not very well known. In this study, leaves of sixteen urban plant species were examined for particle density in June and September 2016 using SEM. The investigated plant species differed in leaf micro-morphology involving trichomes, raised stomata, epicuticular wax crystals and convex epidermal cells forming deep grooves between cells. The particle density on leaves of the investigated plant species was estimated by particle size fraction and leaf side. Particle density was significantly higher on the adaxial (AD) leaf side compared to the abaxial (AB) leaf side and higher for fine-particles than coarse-particles. The effect of trichome density on particle density of the AB and the AD leaf side was indicated to be significant and positive for both coarse and fine-particles in June but not in September. The successive repeated measurements elucidated that features constructing the topography of a leaf surface such as trichomes, stomata, and epidermal cells frequently contributed towards the edge enhancement effect, resulting in exaggerated particle counts. Besides, the mechanical drift contributed to the disparity in particle density measurements. Lastly, the reduction in particle density between successive measurements were imputed on the charging effect. These results enable us to suggest that in addition to characterization of micro-morphological features on a leaf surface, SEM will continue to be a useful approach for determining the particle: shape, size, elemental composition and density of the deposited particles. Nonetheless, the disparity in particle density measurements can occur due to abnormal particle recognition. Based on the results of September, we recommend that within-session successive repeated measurements (~ n ≥ 5) need to be performed to remove measurement uncertainties and obtain reliable quantitative data of particle counts using SEM. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
|
Wos |
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Publication Date |
2021-09-15 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
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ISBN |
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Additional Links |
UA library record |
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Impact Factor |
|
Times cited |
|
Open Access |
OpenAccess |
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| |
Notes |
|
Approved |
Most recent IF: NA |
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| |
Call Number |
UA @ admin @ c:irua:181797 |
Serial |
7822 |
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| Permanent link to this record |
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Author |
Muhammad, S.; Wuyts, K.; Nuyts, G.; De Wael, K.; Samson, R. |
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Title |
Characterization of epicuticular wax structures on leaves of urban plant species and its association with leaf wettability |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Urban Forestry & Urban Greening |
Abbreviated Journal |
Urban For Urban Gree |
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Volume |
47 |
Issue |
47 |
Pages |
126557 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Epicuticular wax (EW) protects the plant’s integrity and acts as a barrier against biotic and abiotic stresses. The micro-structured three-dimensional EW’s and presence of leaf trichomes influence the wettability of a leaf surface. In this study, leaves of 96 perennial urban plant species were examined to determine an association between epicuticular wax structure (EWS) types and leaf wettability and investigate their seasonal variation. The EWS types were identified using Scanning Electron Microscopy (SEM), while leaf wettability was analyzed by measuring the drop contact angle (DCA) on both the abaxial and the adaxial sides of leaves collected from a common garden in June and September 2016. Four distinct EWS types namely thin film, platelets, crusts, and tubules were observed on leaves of investigated plant species in both June and September. The EWS types varied significantly between functional plant types and plant families in both June and September. In June, the abaxial DCA ranged from 56° to 147°, and the adaxial DCA ranged from 56° to 136°. In September, the abaxial DCA ranged from 54° to 130°, and the adaxial DCA ranged from 51° to 125°. The effect of time, leaf side, and EWS type on leaf wettability were significant. Plant species which showed a change in EWS type or clustering from June to September did not show a more pronounced reduction in DCA compared to those species which exhibited a constant EWS type. Findings from our study illustrate that DCA is not a good indicator in determining the different EWS types due to overlapping DCA intervals between the identified EWS types. However, the identified EWS types remained fairly stable throughout the in-leaf season and do not require repeated measurements for characterization. |
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Wos |
000508389000028 |
Publication Date |
2019-12-05 |
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ISSN |
1618-8667 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.4 |
Times cited |
5 |
Open Access |
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Notes |
; The research was funded by the Ontario Student Assistance Program (OSAP # 15103399). The SEM equipment was funded by FWO/Hercules. The authors acknowledge the help of the ENdEMIC group involved in the upkeep of the experimental site. The authors would like to thank the anonymous reviewers for their critical comments and constructive suggestions in improving the quality of the article. ; |
Approved |
Most recent IF: 6.4; 2020 IF: 2.113 |
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Call Number |
UA @ admin @ c:irua:164906 |
Serial |
5504 |
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Author |
Muia, L.M.; Van Grieken, R. |
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Title |
Determination of rare earth elements in geological materials by total reflection X-ray fluorescence |
Type |
A1 Journal article |
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Year |
1991 |
Publication |
Analytica chimica acta |
Abbreviated Journal |
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Volume |
251 |
Issue |
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Pages |
177-181 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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ISSN |
0003-2670; 1873-4324 |
ISBN |
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Additional Links |
UA library record |
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Impact Factor |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:663 |
Serial |
7786 |
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Author |
Muia, L.M.; Van Grieken, R. |
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Title |
Energy-dispersive X-ray fluorescence analysis of geological materials in borax beads using Tertian's binary coefficient approach combined with internal standard addition |
Type |
A1 Journal article |
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Year |
1991 |
Publication |
X-ray spectrometry |
Abbreviated Journal |
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Volume |
20 |
Issue |
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Pages |
179-183 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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ISSN |
0049-8246 |
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Additional Links |
UA library record |
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no |
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Call Number |
UA @ admin @ c:irua:662 |
Serial |
7903 |
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