References of "Strivay, David"
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See detailInvestigation of speckle syndrome affecting late 1920s oil paintings by René Magritte
Defeyt, Catherine ULiege; Vandepitte, Francisca; Mazurek, Joy et al

in van den Berg, KJ; Bonaduce, I; Burnstock, A (Eds.) et al Conservation of Modern Oil Paintings (in press)

Six early oil paintings by Magritte from the Royal Museums of Fine Arts of Belgium are affected by networks of dark speckle-like stains, referred here as speckle syndrome. A systematic approach appeared ... [more ▼]

Six early oil paintings by Magritte from the Royal Museums of Fine Arts of Belgium are affected by networks of dark speckle-like stains, referred here as speckle syndrome. A systematic approach appeared to be a useful way to elucidate the mechanism(s) and the compound(s) responsible for the speckle appearance. Indeed, a comparative study of the visible symptoms, the painting materials and past environmental conditions, facilitated the discovery of the common denominators shared by speckled artworks and, consequently supporting conclusions about the origins of related degradation process . [less ▲]

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See detailElemental quantification and radioactive characterization of soil from Douala Bassa Area: littoral region of Cameroon using EDXRF and γ-spectrometry technics
Guembou Shouop, Cébastien Joel ULiege; Moyo, Maurice Ndontchueng; Mekongtso, Eric Jilbert Nguelem et al

in Environmental Research Communications (in press)

The objectives of the present work were to characterize the investigated soil using Energy Dispersive X-Ray Fluorescence (EDXRF) and to evaluate the radioactivity concentration of the primordial ... [more ▼]

The objectives of the present work were to characterize the investigated soil using Energy Dispersive X-Ray Fluorescence (EDXRF) and to evaluate the radioactivity concentration of the primordial radionuclides with gamma-ray spectrometry based High Purity Germanium (HPGe) detector. Soil characterization using EDXRF in the present study gives an overview of the geological origin or provenience of the investigated area. As a result, the analysed soil samples can be classified chemically as Fe-soil and are illustrative dregs from the Continental margin because of high concentration of Fe (where the concentration of Fe in different soil sample ranged from 14.78% to 22.26 %) in all the investigated samples. The plotting of Al2O3/SiO2 (%) as a function of Fe2O3 and MgO (%) for the eighteen investigated samples points from Douala and a diagram for the tectonic discrimination of sediment provenance evidenced that all soil samples are residue from Passive margins. The observed activity concentration profile of the primordial radionuclides and the calculated radium equivalent activity show that no significant radiological risk can be observed for inhabitance within the study areas. As regard to that, the obtained results of the two analytical techniques can be seen as a baseline data for future investigations about elemental composition and radioactivity background levels in the study area. [less ▲]

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See detailBackscattered electron emission after proton impact on gold nanoparticles with and without polymer shell coating
Hespeels, Felicien; Heuskin, Anne-Caherine; Tabarrant, Tijani et al

in Physics in Medicine and Biology (in press)

This work aims at measuring experimentally proton induced secondary electron energy spectra after interaction with Gold Nano Particles (GNPs) and polymer-coated GNPs. Backscattered electron energy spectra ... [more ▼]

This work aims at measuring experimentally proton induced secondary electron energy spectra after interaction with Gold Nano Particles (GNPs) and polymer-coated GNPs. Backscattered electron energy spectra were collected over a 0 to 1000 eV energy range using a Retarding Field Analyzer. This paper presents the spectra obtained for proton beam energies of 0.5 and 2 MeV and diameter 2.5 and 3.8 nm GNPs. The spectra were also measured for 3.8 nm GNPs after 5 and 10 MeV proton irradiations. GNPs were deposited on a 100 nm carbon film. Each experimental spectrum was compared with dedicated simulations based on existing numerical models used in the TRAX and Geant4 Monte Carlo codes. For 100 nm carbon target, good agreement between experimental, TRAX and Geant4 simulation results can be observed. For 3.8 nm GNPs, the TRAX simulations reproduce with good agreement the electron energy spectra produced after 0.5, 2, 5 and 10 MeV proton irradiations, while Geant4 spectra display a lower secondary electron yield at low energy (<600eV) for all the studied energies. This underestimation can mostly be explained by the 790 eV threshold applied in the condensed history model used by Geant4 which impacts the secondary electron energy distribution. Results obtained for carbon and gold targets highlight the impact of the secondary electron production threshold for proton ionization process considered in condensed history models. The experimental results demonstrate that the single interaction approach used in TRAX is adapted to reproduce secondary electron emission from GNPs. On the other hand, the standard electron generation threshold implement in G4BetheBlochModel and G4BraggModel condensed-history models used in Geant4 is not adapted to reproduce low energy electron emission in gold targets. Finally, the results highlight that the GNP coating leads to a decrease of the electron yield and mostly affects low energy electrons (<500eV) emitted from GNPs. [less ▲]

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See detailPIXE-PIGE and Proton Activation Analysis of Analysis of Roman archeological artefacts
Strivay, David ULiege; Chene, Grégoire ULiege; Dienst, Simon ULiege et al

Poster (2019, June 11)

A combination of 3MeV proton PIXE-PIGE, MA-XRF and 10-15 MeV proton activation analysis has been recently applied on the external beam line of the cyclotron of IPNAS/CEA laboratory from the University of ... [more ▼]

A combination of 3MeV proton PIXE-PIGE, MA-XRF and 10-15 MeV proton activation analysis has been recently applied on the external beam line of the cyclotron of IPNAS/CEA laboratory from the University of Liège, and thus, to a wide variety of archaeological specimens (glass, pottery (terra sigillata), mortars and pigments) all provided by on-going studies and excavations of housing materials, wall decorations, and vessels led on two remarkable Roman sites: First, from an important agricultural complex excavated on an artificial terrace from a republican town, Artena, located, 40 km South-East from Rome, near the Via Latina and the Campania and second, from the Domus dei bucrani, a house dating from the end of the Republican era discovered on the site of the Schola of the Trajan in Ostia. The aim of the present work is to explore and report the specific analytical interests of Charge Particle Activation Analysis implemented with protons ranging from 10 to 15 MeV, as a non-invasive analytical technique for the detection of elements with Z = 11-40 and beyond, and to address its suitability to solve questions raised by archaeologists. We present in this paper the preliminary results obtained following methodologies reported in recent pioneering and more recent works1-4 and emphasize on the achieved sensitivities (Limits of Detections) for elements as Ca, Ti, V, Cr, Fe, Cu, Zn, As, Sr, Y, Zr and Sb ranging from percentage to parts per million (ppm) levels. [less ▲]

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See detailMaterial analysis and testing using a proton therapy facility
Strivay, David ULiege; Chene, Grégoire ULiege

Conference (2019, June 10)

A new Proteus (IBA) proton therapy facility will be installed at the Charleroi hospital in Belgium. In addition to medical applications, material analysis and testing will be developed. We will present ... [more ▼]

A new Proteus (IBA) proton therapy facility will be installed at the Charleroi hospital in Belgium. In addition to medical applications, material analysis and testing will be developed. We will present here the facility and the future material projects with this machine. A special feature will be the ability to get proton beams from 5 to 230 MeV. Ion beams can be used to modify the properties of materials or to carry out ionizing radiation withstand tests, for example for the space industry sector. Studies for applications in the space domain will mainly include radiation withstand testing of electronic components and coatings for the space industry. These measurements will be performed at different energies between 30 and 200 MeV. These energies are required to model the SEE (Single Event Effects) which are one of the main degradation phenomena for space systems subjected to the solar wind. The characteristics in terms of beam size and especially energy modulation will allow to associate ion beam analysis techniques such as PIXE (Particle Induced X-Ray Emission) and PIGE (Particle Induced Range ray emission). in the high energy mode to follow changes in irradiated materials in real time. The use of high energy beam (> 5MeV) will allow the effects to be analyzed at greater depths than by conventional techniques. These studies can therefore also be extended to other areas of research, particularly for the analysis of cultural heritage objects. As with the study of spatial components, the PBS mode (Pencil Beam Scanning) will accurately measure and modulate the dose received by each element of irradiated systems. [less ▲]

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See detailInsight in René Magritte's reused paintings
Defeyt, Catherine ULiege; Vandepitte, Francisca; Herens, Elodie ULiege et al

Conference (2019, May 08)

The research project, Magritte on practice, consists of the systematic study of the world's largest collection of works painted by the Belgian surrealist (1898-1967), housed at the Magritte Museum in ... [more ▼]

The research project, Magritte on practice, consists of the systematic study of the world's largest collection of works painted by the Belgian surrealist (1898-1967), housed at the Magritte Museum in Brussels, through a large panel of non-invasive scientific imaging and analytical techniques (Raman, FTIR, MA-XRF, hyperspectral, IRR, XRR and digital microscopy) [1]. The technical and material study conducted on a corpus of works covering the entire career of the artist (60 oil paintings realised between 1921 and 1967), appeared highly informative about the making process of Magritte’s pictures but also lead to the discovery of six overpainted compositions, among which the last missing part of La pose enchantée, a 1927 large-scale painting transformed into four separate new pictures that are currently dispersed across the world [2]. The present study proposes an overview of the freshly discovered paintings and explores how the painter reused specific elements from the sacrificed compositions for creating the new ones. References [1] C. Defeyt and F. Vandepitte, (in preparation). René Magritte: The artist’s materials. (Los Angeles, CA: Getty Publications) [2] C. Defeyt, E. Herens, F. Leen, F. Vandepitte and D. Strivay, Heritage Sci., 6 (2018) [less ▲]

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See detailCharacterisation and study of degradation of daylight and UV-light fluorescent pigments in modern art through non-invasive methods
Rigoreau, Manon ULiege; Defeyt, Catherine ULiege; Strivay, David ULiege

Poster (2019, May)

Artists started to experiment fluorescent colours shortly after the discovery of daylight pigments by the Switzer brothers in the 1940s. It is a new way of expression for painters from the 20th century ... [more ▼]

Artists started to experiment fluorescent colours shortly after the discovery of daylight pigments by the Switzer brothers in the 1940s. It is a new way of expression for painters from the 20th century such as Andy Warhol, Martial Raysse, Keith Haring and Pierre Alechinsky. More recently, artists from the 21st century use the daylight colours through new technics like aerosol spray paint [1]. It is well known that some fluorescent pigments are unstable. Indeed, phenomena of discolourations and fluorescence losses are often observed. The companies that provide this type of pigments kept secret the composition of their paints and aerosols. Moreover, knowledge of materials used by artists is so important for the history of the art of techniques but also for conservation issues. The aim of the study is to characterise and found identification markers from distinct fluorescent colours, from different manufacturers, using non-invasive methods namely Raman [2] and FT-IR spectroscopy, macro-XRF, X-ray diffraction and hyperspectral imaging. In a second step, after an artificial aging, the goal will be to observe how each pigment evolve to discern which are the most subject to the fading phenomenon. The final step of this study is to find the most optimal analytic strategy for the analysis of works of art, preserved at the Royal Museums of Fine Arts of Belgium, to identify pigments that are more susceptible to fade and enforce preventive conservation for this one. References [1] A. Colombini and C. Valageas, Technè, 38 (2013) 34-38 [2] W. Fremout, in: Conference paper from IRUG 11. (Boston, MA) (2014) [less ▲]

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See detailMulti-analytical study of mural paintings from a Republican house from 1st BC in Ostia
Herens, Elodie ULiege; Defeyt, Catherine ULiege; Motta, Lucie ULiege et al

Poster (2019, May)

Ostia Antica, the ancient port of Rome, is overflowing with many remains, proofs of the greatness and the important activity of this area. Among them, the Schola del Traiano, along the Decumanus Maximus ... [more ▼]

Ostia Antica, the ancient port of Rome, is overflowing with many remains, proofs of the greatness and the important activity of this area. Among them, the Schola del Traiano, along the Decumanus Maximus in the neighbourhood of Porta Marina , presents a complex history. In addition to the excavation by archaeologists of three successive buildings on this parcel, the discovery of an uncommon dwarfs frieze (dating from 40 - 30 BC) brought attention. Usually depicted in decadent or ridiculous scenes, dwarfs are pictured here in scenes of daily life. This frieze is surrounded by other very elaborated friezes and tiles: Green and red masks friezes, dentils, the dwarfs frieze, a vegetal frieze, coloured tiles, a fruits frieze, and big red tiles surrounded by coloured lines combine to form a colourful room decoration. To deepen our understanding of this particular decor, various complementary analytical techniques were used: Raman spectroscopy, MA-XRF, hyperspectral imaging and digital microscopy. Besides the identification of the pigments used for each colour (Egyptian blue, cinnabar, iron oxide, chalk, ...), these techniques also allow to compare the different decoration parts together and to highlight common points and differences between them, in term of chemical composition but also concerning the decor elaboration and the successive steps in the painting implementation. [less ▲]

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See detailAnalysis of archeological artefacts from Ostia and Arena Roman sites by PIXE-PIGE and Proton Activation Analysis
Strivay, David ULiege; Chene, Grégoire ULiege; Dienst, Simon ULiege et al

Conference (2019, March)

A combination of 3MeV proton PIXE-PIGE, MA-XRF and 10-15 MeV proton activation analysis has been recently applied on the external beam line of the cyclotron of IPNAS/CEA laboratory from the University of ... [more ▼]

A combination of 3MeV proton PIXE-PIGE, MA-XRF and 10-15 MeV proton activation analysis has been recently applied on the external beam line of the cyclotron of IPNAS/CEA laboratory from the University of Li`ege, and thus, to a wide variety of archaeological specimens (glass, pottery (terra sigillata), mortars and pigments) all provided by on-going studies and excavations of housing materials, wall decorations, and vessels led on two remarkable Roman sites: First, from an important agricultural complex excavated on an artificial terrace from a republican town, Artena, located, 40 km South-East from Rome, near the Via Latina and the Campania and second, from the Domus dei bucrani, a house dating from the end of the Republican era discovered on the site of the Schola of the Trajan in Ostia. The aim of the present work is to explore and report the specific analytical interests of Charge Particle Activation Analysis implemented with protons ranging from 10 to 15 MeV, as a non-invasive analytical technique for the detection of elements with Z = 11-40 and beyond, and to address its suitability to solve questions raised by archaeologists. We present in this paper the preliminary results obtained following methodologies reported in recent pioneering and more recent works [1-4] and emphasize on the achieved sensitivities (Limits of Detections) for elements as Ca, Ti, V, Cr, Fe, Cu, Zn, As, Sr, Y, Zr and Sb ranging from percentage to parts per million (ppm) levels. [less ▲]

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See detailEarly Medieval Tesserae in Northwestern Europe
Van Wersch, Line ULiege; Verslype, Laurent; Strivay, David ULiege et al

Book published by Habelt (Verlag) (2019)

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See detailExperimental measurements validate the use of the binary encounter approximation model to accurately compute proton induced dose and radiolysis enhancement from gold nanoparticles
Hespeels, F.; Lucas, S.; Tabarrant, T. et al

in Physics in Medicine and Biology (2019), 64(6),

In protontherapy, it has been suggested that nanoparticles of high-Z material like gold (GNP) could be used as radiosensitizers. The origin of this enhancement phenomenon for proton radiation is not yet ... [more ▼]

In protontherapy, it has been suggested that nanoparticles of high-Z material like gold (GNP) could be used as radiosensitizers. The origin of this enhancement phenomenon for proton radiation is not yet well understood and additional mechanistic insights are required. Previous works have highlighted the good capabilities of TRAX to reproduce secondary electron emission from gold material. Therefore, TRAX cross sections obtained with the binary encounter approximation (BEA) model for proton ionization were implemented within Geant4 for gold material. Based on the TRAX cross sections, improved Geant4 simulations have been developed to investigate the energy deposition and radical species production around a spherical gold nanoparticle (5 and 10 nm in diameter) placed in a water volume during proton irradiation. Simulations were performed for incident 2 MeV proton. The dose enhancement factor and the radiolysis enhancement factor were quantified. Results obtained with the BEA model were compared with results obtained with condensed-history models. Experimental irradiation of 200 nm gold films were performed to validate the secondary electron emission reproduction capabilities of physical models used in Monte Carlo (MC) simulations. TRAX simulations reproduced the experimental backscattered electron energy spectrum from gold film with better agreement than Geant4. Results on gold film obtained with the BEA model enabled to estimate the electron emission from GNPs. Results obtained in our study tend to support that the use of the BEA discrete model leads to a significant increase of the dose in the near vicinity of GNPs (<20 nm), while condensed history models used in Geant4 seem to overestimate the dose and the number of chemical species for increasing distances from the GNP. Based on discrete BEA model results, no enhancement effect due to secondary electron emitted from the GNP is expected if the GNP is not in close proximity to key cellular functional elements (DNA, mitochondria...). © 2019 Institute of Physics and Engineering in Medicine. [less ▲]

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See detailLes matériaux des mosaïques de Germigny-des- Prés
Van Wersch, Line ULiege; Kronz, Andreas; Simon, Klaus et al

in Bulletin du Centre d'Études Médiévales d'Auxerre (2019), Hors-série n°11

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See detailThis is not Magritte
Defeyt, Catherine ULiege; Brachot, Isy; Strivay, David ULiege

Poster (2018, July)

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See detailNon-invasive analysis of mural paintings from a Republican house from 1st B.C. in Ostia
Herens, Elodie ULiege; Defeyt, Catherine ULiege; Morard, Thomas ULiege et al

Conference (2018, May 23)

This paper is a comprehensive analytical study of the murals belonging to an ancient Roman house through the characterization of materials. The project focuses on the wall paintings of the Domus dei ... [more ▼]

This paper is a comprehensive analytical study of the murals belonging to an ancient Roman house through the characterization of materials. The project focuses on the wall paintings of the Domus dei bucranes, a house of the end of the Republican era discovered on the site of the Schola of Trajan in Ostia. This Domus has undergone several phases of development in the 1st century BC before being destroyed around 20 BC. A new house was immediately rebuilt after a major change from the ground, which allowed exceptional preservation of the decoration system. The results complement our knowledge of Roman painting techniques during the 1st century BC and also provide a comprehensive multidisciplinary approach to the problem of conservation of wall paintings. These two related objectives have been studied using non-destructive testing methods (MA-XRF, FTIR and Raman spectroscopy). The analyzes have been performed in situ using our mobile systems. The different set-ups had to be modified in order to be able to work on horizontal surfaces, specially our XRF scanner. The study of the pictorial layers address various issues in the field of archaeology: what technique has been implemented? Does the same technique was used in both phases of the development of Domus? Do they correspond to the techniques described by ancient writers? These responses are compared to those observed in other sets of murals dating from the 1st century BC. [less ▲]

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See detailMAGRITTE ON PRACTICE: FINDING LOST COMPOSITIONS BY NON-INVASIVE TECHNIQUES
Strivay, David ULiege; Defeyt, Catherine ULiege; Vandepitte, Francisca et al

Conference (2018, May)

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See detailComparative study of the speckles syndrome affecting four Magritte’s oil paintings from 1927
Defeyt, Catherine ULiege; Herens, Elodie ULiege; Leen, Frederik et al

Poster (2018, May)

In the frame of the on-going research project Magritte on practice, the sixty-three paintings from the Magritte Museum collection (Royal Museums of Fine Arts of Belgium) are systematically investigated ... [more ▼]

In the frame of the on-going research project Magritte on practice, the sixty-three paintings from the Magritte Museum collection (Royal Museums of Fine Arts of Belgium) are systematically investigated through complementary analytical and imaging methods. On this occasion, the presence of dark round stains looking like speckles, has been noticed on the paint surface of four 1927 oil paintings, namely La voleuse, Le démon de la perversité, L’homme du large and Le joueur secret. When observed under digital microscope, those appear as dark micro-cracks forming concentric cobweb-like networks, with dark accretions and with or without whitish protrusions. The proliferation of such dark stains appears as a typical visual damage, occurring in Magritte oil paintings dating from 1927. Indeed, further 1927 Magritte’s oils on canvas, for instance, L’assassin menacé from the MoMA (New York) and Le sens de la nuit from The Menil Collection (Houston), exhibit the same visually disturbing alterations, referred here as speckles syndrome. Duffy et al. [1] have pointed out the probable linkage between the visual damages observed on L’assassin menace, and the aggregates of metal soaps formed at the painting surface. In the present study, La voleuse, Le démon de la perversité, L’homme du large and Le joueur secret, have been investigated in parallel and in the same experimental conditions, by means of non-invasive imaging and analytical methods, including digital microscopy, UV and Vis high-resolution imagery, FTIR, RS, pXRF and MA-XRF techniques. The objective of this research was to collect technical and compositional information, sufficiently abundant and significant, to formulate substantiated conclusions about the painting materials and the mechanisms involved in the speckles syndrome. The comparison of the acquired analytical data and images allowed highlighting several common denominators between the four damaged paintings. For example, the speckled surfaces always contains Ca- and P-based black pigment (bone or ivory black), unidentified chlorinated compound(s) and lead white and/or zinc white. Interestingly, the FTIR spectra recorded from speckled areas and from unaffected surfaces tend to evidence the presence of metal soaps in both cases. [less ▲]

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See detailMonte Carlo method for gamma spectrometry based on GEANT4 toolkit: Efficiency calibration of BE6530 detector
Guembou Shouop, Cébastien Joel ULiege; Ndontchueng Moyo, Maurice; Nguelem Mekongtso, Eric Jilbert et al

in Journal of Environmental Radioactivity (2018), 189

The combination of gamma-ray spectrometry, the development of related Monte Carlo method and the GEANT4 (GEometry ANd Tracking) toolkit have been developed for gamma spectrometry simulation. The main ... [more ▼]

The combination of gamma-ray spectrometry, the development of related Monte Carlo method and the GEANT4 (GEometry ANd Tracking) toolkit have been developed for gamma spectrometry simulation. The main objective was to validate simulation models of broad energy germanium (BEGe) detector geometry built in our laboratory (BE6530 model). Monte Carlo simulation of the geometry of BE6530 detector for efficiency calibration was carried out with GEANT4 toolkit. The simulated efficiencies curves using MC were compared with experimental results. Measurement uncertainties for both simulation and experimental estimations of the efficiency were assessed in order to see whether the consequences of the realistic measurement fall inside adequate cut-off points. The validation of the simulation was carried out by experimentally estimating the activity concentration in a reference sample and the comparison showed good correlation between experimental and simulation. Therefore, from the outcomes of this study, it can be concluded that Monte-Carlo simulation is a helpful, reasonable option that additionally gives more prominent adaptability, greater flexibility, precision and accuracy, and gained time when determining the detector response and efficiency in routine of environmental radioactivity monitoring. [less ▲]

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See detailNicolas Schöffer’s collection: from the artist’s studio to the museum
D'Haenens, Manon ULiege; Verbeeck, Muriel ULiege; Strivay, David ULiege

in Rivenc, Rachel; Bek, Reinhard (Eds.) Keep it moving ? Conserving kinetic art: Proceedings from the meeting organized by the Getty Conservation Institute, the ICOM-CC Modern Materials and Contemporary Art Working Group, and Museo del Novecento (2018, March)

Detailed reference viewed: 59 (11 ULiège)