References of "Strivay, David"
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See detailA remote controlled XRF system for field analysis of cultural heritage objects
Hocquet, François-Philippe ULg; Garnir, Henri-Pierre ULg; Marchal, André ULg et al

in X-Ray Spectrometry [=XRS] (2008), 37(4), 304-308

X-ray fluorescence (XRF) is a nondestructive, multielemental, fast and cost-effective analysis technique. It can be applied in a nonvacuum environment directly on the samples without any preparation. As ... [more ▼]

X-ray fluorescence (XRF) is a nondestructive, multielemental, fast and cost-effective analysis technique. It can be applied in a nonvacuum environment directly on the samples without any preparation. As archaeological and historical objects are often unique and may not be easily movable, a mobile XRF detector system allowing in situ analysis is ideally suited for archaeometric applications. A mobile system was designed and built at the IPNAS laboratory to provide such analyses. The system includes an industrial grade x-ray generator which supplies the primary x-ray beam, an air-cooled silicon rift Detector detector (SDD) with a 5-mm(2) active area. The data acquisition system measures the energy and the intensity of the secondary fluorescence x-rays. The detector signal is amplified and analyzed by a multichannel recorder coupled to a microcomputer running JavaSpectre which visualizes and analyzes spectra obtained from the detector. The detection head, containing the detector, the x-ray tube and its power supply, are fixed on a movable platform allowing independent vertical and horizontal movement. All displacements are controlled by a hand-held personal digital assistant (PDA) (Palm) which exchanges data with microcontrollers embedded in the system providing a very precise positioning of the detector over a surface of many square meters. This system control, as well as a typical application of this XRF spectrometer for analyzing pigment composition of a wall painting, will be described. Copyright (C) 2008 John Wiley & Sons, Ltd. [less ▲]

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See detailMaya blue-green pigments found in Calakmul, Mexico: a study by Raman and UV-visible spectroscopy
Moreno, Renata Garcia; Strivay, David ULg; Gilbert, Bernard ULg

in Journal Of Raman Spectroscopy (2008), 39(8), 1050-1056

After more than two decades of fieldwork in the Maya archaeological site of Calakmul, Mexico, numerous remnants of blue and green pigments have been reported on wall paintings, as well as on funerary ... [more ▼]

After more than two decades of fieldwork in the Maya archaeological site of Calakmul, Mexico, numerous remnants of blue and green pigments have been reported on wall paintings, as well as on funerary paraphernalia, such as masks, miniatures and vases. The importance of these pigments is linked to the sacred values that Maya people associate with blue and green colours since pre-Columbian times. These hues symbolise water, and are therefore associated with fertility and regeneration. This paper aims to perform a survey of the blue and green pigments used in the Early Classic and Late Classic periods in Calakmul (300-850 A.D.), in order to have a better understanding of their chemical composition and origin. Analyses were performed on microsamples using Raman and UV-visible spectroscopies to evaluate the possibilities that these techniques can offer in future in situ researches on Mesoamerican archaeological materials and objects. With these analyses, we have documented a large blue-green chromatic palette, which includes the earliest Blue Maya and Green Maya known to date, as well as malachite, pseudomalachite and an unknown-up-to-now blue-green mineral pigment, veszelyite, used specifically for ritual objects. The results indicate a careful selection of imported products and the mastering of a complex ancient Maya pictorial tradition. Copyright (c) 2008 John Wiley & Sons, Ltd. [less ▲]

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See detailProvenance of Belgian Merovingian garnets by PIXE on IPNAS Cyclotron
Mathis, François ULg; Vrielynck, Olivier; Laclavetine, Kilian et al

Poster (2007)

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See detailVeszelyite: A New Blue-Green Maya Pigment
Garcia Moreno, Renata; Mathis, François ULg; Strivay, David ULg

Poster (2007)

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See detailThe recognition of biological cells utilizing quantitative phase microscopy system
Veselov, O.; Lekki, J.; Polak, W. et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2005), 231

Single ion bombardment of biological cells using an ion microprobe is a promising technique. However, for microprobe investigations of biological processes at a cellular level the precise recognition of a ... [more ▼]

Single ion bombardment of biological cells using an ion microprobe is a promising technique. However, for microprobe investigations of biological processes at a cellular level the precise recognition of a single cell and particularly of its nucleus is required. Moreover, cells must be examined in their natural state and environment (i.e. without previously being killed, preferentially not fixed nor stained) and, also, the use of ultraviolet light for cells observation should be avoided. Additionally, in order to obtain statistically significant results of irradiation, the possibility of fast automatic recognition of thousands of objects must be provided. Because computer recognition strongly depends on the quality of an image, the optical imaging system is of crucial importance. For this purpose one of the best solutions could be the Quantitative Phase microscopy (QPm) technique. QPm is the recent digital technique of phase contrast microscopy, providing quantitative phase and intensity data obtained from a series of defocused images. The following phase contrast modalities may be generated digitally from the computed QPm phase data with a greater degree of flexibility: Pure phase images (intensity-free), standard phase contrast (e.g. Zernike phase contrast), differential interference contrast (DIC), Hoffman modulation contrast, and simulated darkfield. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailApplication of PIXE and PIGE under variable ion beam incident angle to several fields of archaeometry
Weber, Georges ULg; Martinot, L.; Strivay, David ULg et al

in X-Ray Spectrometry [=XRS] (2005), 34(4, JUL-AUG), 297-300

For several years, the specific features of PIXE and PIGE have made them very attractive in the field of archaeometry. Among them, non-destructivity is one of the most important. The possibility of ... [more ▼]

For several years, the specific features of PIXE and PIGE have made them very attractive in the field of archaeometry. Among them, non-destructivity is one of the most important. The possibility of working under atmospheric pressure is also important because of the very different shapes and sizes of the artefacts concerned. However, these ion beam techniques suffer from the same disadvantage: the information coming from x-rays or),brays produced at different places along the charged particle path is integrated. That prevents one from taking into account the possible element concentration gradients due to multilayered systems or diffusion processes. This paper presents several applications of PIXE and PIGE applied under variable ion beam incident angle. PIGE has been mainly used for studying ancient glass items or glass windows in order to detect or evaluate the glass corrosion process. The examples given for PIGE deal with Roman and Merovingian glass objects and cathedral glass windows and PIXE applications concern studies for resolving the multilayered structure of easel paintings. The set-up allowing one to perform the measurements should be very stable, the rotation axis should pass through the beam axis and the detector should follow the sample movement. Copyright (c) 2005 John Wiley [less ▲]

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See detailImmobilization of silver in polypyrrole/polyanion composite coatings: Preparation, characterization, and antibacterial activity
Ignatova, Milena; Labaye, David; Lenoir, Sandrine ULg et al

in Langmuir (2003), 19(21), 8971-8979

Thin films of polypyrrole doped by polyanions have been deposited onto stainless steel and carbon fibers by anodic electropolymerization of pyrrole in the presence of an anionic polyelectrolyte in water ... [more ▼]

Thin films of polypyrrole doped by polyanions have been deposited onto stainless steel and carbon fibers by anodic electropolymerization of pyrrole in the presence of an anionic polyelectrolyte in water. Films with a thickness smaller than 600 nm have been formed, which strongly adhere to the solid supports. The polymeric dopant has been selected for its ability to complex silver ions. Scanning electron microscopy, Rutherford backscattering analyses, and IR spectroscopy have confirmed that silver is actually immobilized in the films and provides them with an antibacterial activity against the Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus. [less ▲]

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See detailComplexation of uranyl ions by polypyrrole doped by sulfonated and phosphonated polyethyleneimine
Leroy, D.; Martinot, Lucien; Mignonsin, P. et al

in Journal of Applied Polymer Science (2003), 88(2), 352-359

Branched polyethyleneimine (PEI) was sulfonated by reaction with chloropropanesulfonylchloride and phosphonated by reaction with phosphorous acid and formaldehyde. The accordingly formed polyanions were ... [more ▼]

Branched polyethyleneimine (PEI) was sulfonated by reaction with chloropropanesulfonylchloride and phosphonated by reaction with phosphorous acid and formaldehyde. The accordingly formed polyanions were used as doping agents for polypyrrole (PPy). The amount of doping polyanions into thin films of PPy was measured by Rutherford back-scattering. These films were tested for their capacity to extract uranyl ions from liquid wastes of low level activity. The uranium content was determined by neutron activation analysis, autoradiography, and gravimetry of uranium oxide after calcination. The resistance against static and dynamic leachings was also estimated. [less ▲]

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See detailStudy of color centers induced by PIXE irradiation
Absil, J.; Garnir, Henri-Pierre ULg; Strivay, David ULg et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2002), 198(1-2), 90-97

The particle induced X-ray emission method is perfectly adapted to the study, by external beam, of art objects (like paintings) and allows non-destructive analysis of the atomic composition of the target ... [more ▼]

The particle induced X-ray emission method is perfectly adapted to the study, by external beam, of art objects (like paintings) and allows non-destructive analysis of the atomic composition of the target. However, a strange phenomenon occurs during irradiation on some pigments: dark brownish stains appear, and this could be due to the formation of color centers. In fact, these darkening spots progressively fade out and disappear after a few weeks. Heat and UV light accelerate the decreasing process. The aim of this study is to understand the physical processes of the stain creation and to find a way to make stains disappear, avoiding any damage for the painting. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailAn empirical formula for L line X-ray production cross-section of elements from Ag to U for protons below 3.5 MeV
Strivay, David ULg; Weber, Georges ULg

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2002), 190

When computing element concentration from proton induced X-ray emission analysis, an important parameter is the X-ray production cross-section. There have been numerous experimental and theoretical works ... [more ▼]

When computing element concentration from proton induced X-ray emission analysis, an important parameter is the X-ray production cross-section. There have been numerous experimental and theoretical works in this field. Nonetheless, although there is a simple analytical formula to compute K X-ray cross-sections, there is no such ones for the L lines. We present here analytical formulas for the cross-section of the three main X-ray lines L-alpha L-beta and L-gamma based on experimental data. So far, nearly 3000 values of cross-sections for elements from Ag to U and proton energy ranging from 0.5 to 3.5 MeV have been collected from various references. This experimental data set has been fitted for each Xray line with an exponential function depending on the proton energy and on the element atomic number. These fitted values have then been compared to the experimental data and with theoretical values obtained by the ECPSSR theory and Coster-Kronig fluorescence yields. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailUse of PIXE-PIGE under variable incident angle for ancient glass corrosion measurements
Weber, Georges ULg; Strivay, David ULg; Martinot, Lucien et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2002), 189

Although glass is usually considered as a very stable archaeological material, it can undergo severe degradation. Soda-lime glass, the most common glass throughout ancient times, is particularly sensitive ... [more ▼]

Although glass is usually considered as a very stable archaeological material, it can undergo severe degradation. Soda-lime glass, the most common glass throughout ancient times, is particularly sensitive to this problem. The glass surface absorbs moisture from its environment and the contact with CO2 causes Na2O and NaOH to convert to Na2CO3, which is extremely hygroscopic. The subsequent unstable glass layer can be leached out and causes decomposition of the glass. The non-destructive PIGE-PIXE method of investigation allows detection of this phenomenon even if no visible effect appears. The variable incident angle method is able to discern the depth of the degradation. One aim of such studies is the possible dating or at least fake detecting of archaeological materials, Furthermore, even objects of large size can be investigated with the atmospheric PIGE-PIXE Set-LIP, Some examples of measurements on ancient glass are given. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailLe GPS et la Physique
Garnir, Henri-Pierre ULg; Strivay, David ULg; Bastin, Thierry ULg

in Science and Culture (2002), 380

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See detailControlled exchange of metallic cations by polypyrrole-based resins
Jérôme, Christine ULg; Martinot, Lucien; Strivay, David ULg et al

in Synthetic Metals (2001), 118(1-3), 45-55

Binding and release of various cations by polarization of polypyrrole based exchange-resins has been studied. The reversibility of the process has been investigated by electrochemical and nuclear ... [more ▼]

Binding and release of various cations by polarization of polypyrrole based exchange-resins has been studied. The reversibility of the process has been investigated by electrochemical and nuclear techniques. It clearly depends on both the exchanged-cation and the sulfonated doping-ion. The selectivity of the process has also been analyzed by binding experiments from a mixture of two cations. [less ▲]

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See detailA magnetic and conversion electron Mossbauer spectral study of amorphous Dy20Fe80-yCoy thin films
Fleury-Frenette, Karl ULg; Delwiche, Jacques ULg; Grandjean, Fernande ULg et al

in IEEE Transactions on Magnetics (2001), 37(4), 2311-2314

Amorphous thin films of Dy20Fe80-yCoy, with 0 < y < 20 and of ca. 40 nm thickness, have been prepared by sputtering on polyimide substrates. The 295 K conversion electron Mossbauer spectra (CEMS) of these ... [more ▼]

Amorphous thin films of Dy20Fe80-yCoy, with 0 < y < 20 and of ca. 40 nm thickness, have been prepared by sputtering on polyimide substrates. The 295 K conversion electron Mossbauer spectra (CEMS) of these films consist of broadened sextets which have been analyzed with a distribution of hyperfine fields in which the iron moments are oriented perpendicular to the plane of the film, an orientation which is in agreement with the perpendicular magnetic anisotropy observed herein at 295 K by vibrating sample magnetrometry. The average hyperfine field and isomer shift increase linearly with increasing Co content. Both increases arise from an increase in the electron occupation of the 3d states as the cobalt content increases. [less ▲]

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