References of "Strivay, David"
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See detailLes perles en verre de la nécropole de Bossut–Gottechain : recettes et fabrication
Mathis, François ULg; Vrielynck, Olivier; Leroy, Amandine et al

Conference (2013, April)

La nécropole de Bossut Gottechain est une des plus grandes nécropoles mérovingiennes jamais trouvée en Belgique. Les fouilles conduites entre 2002 et 2006 ont permis de mettre au jour 436 tombes sur une ... [more ▼]

La nécropole de Bossut Gottechain est une des plus grandes nécropoles mérovingiennes jamais trouvée en Belgique. Les fouilles conduites entre 2002 et 2006 ont permis de mettre au jour 436 tombes sur une période d’occupation s’étalant de 470 à 670 ap J.C. Ces tombes contenaient un matériel funéraire important composé d’armes, d’accessoires de vêtement, de récipients en céramique, en métal et en verres, et de bijoux parmi lesquels une quantité inhabituellement importante de perles. Plus de 8000 spécimens ont été retrouvés, la majorité en verre (environ 6800 soit 82% du corpus), mais aussi en ambre, pierre, céramique ou métal. L’abondance de ce matériel et la datation fine de ce site ont permis de dresser une typo-chronologie précise de cette production affinant la description des types et des périodes d’utilisation déjà connus. Nous avons voulu en plus de l’étude purement archéologique de ces perles porter une attention particulière au matériau qui les compose. Une campagne d’analyse physico-chimique a donc été engagée. La méthode choisie a été la spectroscopie PIXE- PIGE en faisceau extrait, cette méthode d’analyse non invasive et très sensible aux éléments légers étant particulièrement adaptée à notre corpus d’objets nombreux mais précieux. Ces analyses ont été conduites sur la ligne de faisceau extrait ARCHEO de l’accélérateur de l’Institut de Physique Nucléaire, Atomique et de Spectroscopie de l’université de Liège. Nous avons pu analyser plus de trois cent perles. Une attention particulière a été portée sur les perles en verres jaune et noire, abondamment représentées dans le corpus, ainsi que sur plusieurs perles dont le type rare ou unique sur le site nous interrogeait. Les résultats de cette recherches ont été particulièrement fructueux car nous avons pu mettre en exergue la pratique connue du remploi de perles en verre romain ou protohistorique à l’époque mérovingienne, et confirmer le changement de recettes d’opacifiant/colorant dès le tout début de la période mérovingienne où l’utilisation d’oxydes d’étain ou de stannates de plomb est généralisée et celle des antimoniates complètement abandonnée. Enfin nous avons pu mettre en évidence l’utilisation d’un verre très riche en plomb pour la fabrication de perles noires dès le début de la période d’occupation du site, verre qui à notre connaissance n’a jamais été documenté [less ▲]

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See detailHigh energy environment offshore deposits in the western Gulf of Corinth, Greece
Beckers, Arnaud ULg; Mortier, Clément; Beck, Christian et al

Conference (2013, April)

Detailed reference viewed: 55 (14 ULg)
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See detailPB15’s discrimination in oil paintings by non-destructive methods
Defeyt, Catherine ULg; Vandenabeele, Peter; Van Pevenage, Jolien et al

Poster (2013, March 29)

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See detailX-ray production cross-sections measurements for high-energy alpha particle beam for Si, Fe and Cu
Dupuis, Thomas; Chene, Grégoire ULg; Marchal, André ULg et al

Conference (2013, March)

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See detailPB15 polymorphic distinction in paint samples by combining micro- Raman spectroscopy and chemometrical analysis
Van Pevenage, Jolien; Defeyt, Catherine ULg; Moens, Luc et al

Poster (2013)

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See detailMicro-Raman spectroscopy and chemometrical analysis for the distinction of copper phthalocyanine polymorphs in paint layers
Defeyt, Catherine ULg; Van Pevenage, Jolien; Moens, Luc et al

in Spectrochimica Acta Part A : Molecular and Biomolecular Spectroscopy (2013), 115

In art analysis, copper phthalocyanine (CuPc) is often identified as an important pigment (PB15) in 20th century artworks. Raman spectroscopy is a very valuable technique for the detection of this pigment ... [more ▼]

In art analysis, copper phthalocyanine (CuPc) is often identified as an important pigment (PB15) in 20th century artworks. Raman spectroscopy is a very valuable technique for the detection of this pigment in paint systems. However, PB15 is used in different polymorphic forms and identification of the polymorph could retrieve information on the production process of the pigment at the moment. Raman spectroscopy, being a molecular spectroscopic method of analysis, is able to discriminate between poly- morphs of crystals. However, in the case of PB15, spectral interpretation is not straightforward, and Raman data treatment requires some improvements concerning the PB15 polymorphic discrimination in paints. Here, Raman spectroscopy is combined with chemometrical analysis in order to develop a procedure allowing us to identify the PB15 crystalline structure in painted layers and in artworks. The results obtained by Linear Discriminant Analysis (LDA), using intensity ratios as variables, demonstrate the ability of this procedure to predict the crystalline structure of a PB15 pigment in unknown paint samples. [less ▲]

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See detailPIXE-PIGE analysis of early medieval window glass from the abbey of Stavelot
Van Wersch, Line ULg; Mathis, François ULg; Biron, Isabelle et al

Poster (2013)

From the 1 st century, glass found in northern Europe was made from a mix of sand and natron that had to be imported from eastern Mediterranean [1]. After the fall of the Roman Empire, glassmakers could ... [more ▼]

From the 1 st century, glass found in northern Europe was made from a mix of sand and natron that had to be imported from eastern Mediterranean [1]. After the fall of the Roman Empire, glassmakers could either recycle existing glass or continue to import material. Then, around the end of the 8 th century, the first testimonies of potash glass, made with sand and trees ashes, are attested [1]. This type of glass would then prevail but the reasons and mechanisms of its appearance remain beyond understanding. They could be linked to the development of architecture and the growing needs of window glass. Founded in the middle of the VII th century, the abbey of Stavelot was a first time ruined by Vikings in 881. In the destruction levels, hundreds fragments of window glass were found [2]. 34 fragments were analysed in PIXE-PIGE at the cyclotron of the Institute of Nuclear and Atomic Physics and of Spectrometry of the University of Liège. The results show coexistence of both natron and potash glass on the site, even in the same archaeological contexts. For the coloration, the recipes to obtain turquoise or amber glass were comparable to those known on other early medieval sites [3], but to make green potash glass the artisans have used to two types of recipes. This shows the need to carry on researches and analysis on early medieval window glass in order to understand its production techniques that are also at the origin of famous gothic stained glass [less ▲]

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See detailInvestigation of advanced materials for fusion alpha particle diagnostics
Bonheure, G.; Van Wassenhove, G.; Hult, M. et al

in Fusion Engineering & Design (2013)

Fusion alpha particle diagnostics for ITER remain a challenging task. Standard escaping alpha particle detectors in present tokamaks are not applicable to ITER and techniques suitable for fusion reactor ... [more ▼]

Fusion alpha particle diagnostics for ITER remain a challenging task. Standard escaping alpha particle detectors in present tokamaks are not applicable to ITER and techniques suitable for fusion reactor conditions need further research and development [1,2]. The activation technique is widely used for the characterization of high fluence rates inside neutron reactors. Tokamak applications of the neutron activation technique are already well developed [3] whereas measuring escaping ions using this technique is a novel fusion plasma diagnostic development. Despite low alpha particle fluence levels in present tokamaks, promising results using activation technique combined with ultra-low level gamma-ray spectrometry [4] were achieved before in JET [5,6]. In this research work, we use new advanced detector materials. The material properties beneficial for alpha induced activation are (i) moderate neutron cross-sections (ii) ultra-high purity which reduces neutron-induced background activation and (iii) isotopic tailoring which increases the activation yield of the measured activation product. Two samples were obtained from GERDA[7], an experiment aimed at measuring the neutrinoless double beta decay in 76Ge. These samples, made of highly pure (9 N) germanium highly enriched to 87% in isotope Ge-76, were irradiated in real D-D fusion plasma conditions inside the TEXTOR tokamak. Comparison of the calculated and the experimentally measured activity shows good agreement. Compared to previously investigated high temperature ceramic material [8], this candidate detector offers better prospects for signal to background S/B ratio, energy resolution and particle selectivity due to a unique alpha particle signature. Applicability to ITER is discussed. Finally, research needs for further development of this diagnostic technique are outlined. © 2013. [less ▲]

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See detailRedox reactions in Prussian blue containing paint layers as a result of light exposure
Samain, Louise ULg; Gilbert, Bernard ULg; Grandjean, Fernande ULg et al

in Journal of Analytical Atomic Spectrometry [=JAAS] (2013)

Prussian blue, a mixed valence pigment, typically KFeIII[FeII(CN)6].xH2O, was the most widely used blue artistic pigment from ca. 1720 to the 1970's but, unfortunately, its paint layers, especially when ... [more ▼]

Prussian blue, a mixed valence pigment, typically KFeIII[FeII(CN)6].xH2O, was the most widely used blue artistic pigment from ca. 1720 to the 1970's but, unfortunately, its paint layers, especially when used in conjunction with a white pigment, tend to fade or turn green upon extended exposure to light. In order to identify the mechanism underlying these changes, paint layers have been prepared with differing amounts of these white pigments and subjected to accelerated light exposure fading. The resulting unfaded and faded paint layers as well as both the Berlin white pigment, Fe2II[FeII(CN)6], and the partially oxidized Berlin green pigment, {KFeIII[FeII(CN)6]}x{FeIII[FeIII(CN)6]}1–x, have been characterized by Raman and iron-57 Mössbauer spectroscopy. The results indicate that, upon fading, the Prussian blue pigment painted with a linseed oil binder and (PbCO3)2Pb(OH)2 or ZnO, and to a lesser extent with TiO2, undergoes a reduction at the exposed paint surface and an oxidation in the bulk of the paint layer. This combined reduction and oxidation disrupts, at least in part, the FeIII–N–C–FeII intervalent electron transfer pathways in Prussian blue thus leading to pigment fading through a reduction in the intervalent electron transfer absorbance at about 700 nm. [less ▲]

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See detailSections efficaces de production de rayonnement gamma sur Li et F
Debande, Vivien; Chene, Grégoire ULg; Strivay, David ULg

Poster (2012, December 11)

Detailed reference viewed: 46 (8 ULg)
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See detailAutomatic X-ray fluorescence scanning mobile system for 2D chemical analysis
Strivay, David ULg; Hocquet, François-Philippe; Dister, Hervé et al

Conference (2012, December)

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See detailX-ray methods
Calvo Del Castillo, Helena ULg; Strivay, David ULg

in Edwards, H; Vandenabeele, P (Eds.) Analytical Archaeometry: Selected Topics (2012)

Detailed reference viewed: 20 (4 ULg)
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See detailFusion alpha and proton diagnostics by thin layer activation
Chene, Grégoire ULg; Bonheure, George; Delhalle, René ULg et al

Conference (2012, September)

Detailed reference viewed: 23 (2 ULg)
See detailStudy of the alteration processes of Prussian blue in laboratory-prepared and genuine paint layers
Samain, Louise ULg; Sanyova, Jana; Strivay, David ULg

Conference (2012, July 09)

The necessity of understanding degradation and alteration processes in a painting's materials is well established for preservation and art history issues. The task is complex because of the highly ... [more ▼]

The necessity of understanding degradation and alteration processes in a painting's materials is well established for preservation and art history issues. The task is complex because of the highly heterogeneous character of an ancient paint layer. In this context we focus on a particular pigment, Prussian blue. Prussian blue is a hydrated ferric ferrocyanide complex, first synthesized in 1704 in Berlin. It has been widely used by artists until the 1970s. However, the permanence of Prussian blue had already been questioned by the mid-eighteenth century, because it exhibits a tendency to fade in light and to turn green. To date, little attention has been devoted to the understanding of the degradation processes of Prussian blue in paint layers. We induced discoloration upon light exposure in commercial and laboratory-synthesized Prussian blue watercolor and oil paint layers by accelerated ageing. Pure Prussian blue painted in a dark shade appears to be extremely light fast but fades when either painted in a lighter shade or mixed with white pigments. We analyzed the paint layers by various techniques, i.e., UV-visible, Fourier transform infrared, Raman, Mössbauer and X-ray absorption spectroscopy. We attributed the fading of Prussian blue to a reduction of the iron(III) ions at the surface of the paint layers. We also observed a partial oxidation of Prussian in the entire paint layer. Finally we confirmed these results by analyzing works of art containing Prussian blue, i.e., a polychrome sculpture, wallpapers and mural decoration sample. [less ▲]

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See detailCrystal Structure and Local Disorder in Modern and Ancient Prussian Blue Pigments
Samain, Louise ULg; Martinetto, Pauline; Bordet, Pierre et al

Poster (2012, June 06)

The necessity of understanding degradation and alteration processes in a painting's materials is well established for preservation and art history issues. The task is however complex because of the highly ... [more ▼]

The necessity of understanding degradation and alteration processes in a painting's materials is well established for preservation and art history issues. The task is however complex because of the highly heterogeneous character of a paint layer, which consists of a mixture of pigments and a binder on a support. In this context we focus on a particular pigment, Prussian blue. Prussian blue is a hydrated ferric ferrocyanide complex, first synthesized in 1704 in Berlin. It has been widely used by artists until the 1970's. However reports of discoloration had already appeared in eighteenth and nineteenth century books. To date, little attention has been devoted to the understanding of the degradation processes of Prussian blue in paint layers. The preparation methods of Prussian blue were rapidly recognized as a contributory factor in the fading of the pigment because they lead to the introduction of impurities in its structure. The crystal structure of Prussian blue is notoriously complex because of the presence of vacancies and local disorder. Unresolved questions about the crystal structure of the soluble variety of Prussian blue, i.e., Prussian blue containing alkali cations, are still found in the literature. We reproduced modern and ancient preparation methods of Prussian blue and analyzed the obtained pigments by high-energy powder diffraction at the beamline ID11, ESRF, Grenoble and at the beamline CRISTAL, Soleil, Paris. The crystal structure of soluble Prussian blue was reviewed by Rietveld refinement and appears to contain approximately a quart of iron(II) sites vacant, similarly to the well-known insoluble crystal structure. The refinement of the pair distribution function extracted from the total scattering signal revealed a local structure different from the average one. The local arrangements are best described by combining three different substructures with different numbers of vacancies and vary upon the type of synthesis. The PDF analysis also evidenced the formation of nanocrystalline ferrihydrite and alumina hydrate in Prussian blue pigments synthesized according to eighteenth-century recipes. The local disorder and the presence of an undesirable iron compound in Prussian blue can help to better understand the degradation mechanisms in paint layers containing this pigment. [less ▲]

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See detailNon-destructive characterization of the Nizet Manuscript (XVIIIth century) : first results
Machowski, Mélanie ULg; Calvo Del Castillo, Helena ULg; Hocquet, François-Philippe et al

Poster (2012, June)

Detailed reference viewed: 47 (8 ULg)