References of "Weber, Georges"
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See detailLa peinture murale à Liège au XVIe siècle : analyse technologique d'une peinture de la cathédrale Saint-Paul de LIège
Oger, Cécile ULg; Denoël, Sophie; Strivay, David ULg et al

in Denoël, Sophie (Ed.) Les peintures murales. Les techniques (2008)

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See detailArchaeometry at the Centre Européen d’Archéométrie-Université de Liège
Calvo Del Castillo, Helena ULg; Mathis, François ULg; Garcia Moreno, Renata et al

Conference (2008)

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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 detailRepetitive transcranial magnetic stimulation improves open field locomotor recovery after low but not high thoracic spinal cord compression-injury in adult rats
Poirrier, Anne-Lise ULg; Nyssen, Yves; Scholtes, Félix ULg et al

in Journal of Neuroscience Research (2004), 75(2), 253-261

Electromagnetic fields are able to promote axonal regeneration in vitro and in vivo. Repetitive transcranial magnetic stimulation (rTMS) is used routinely in neuropsychiatric conditions and as an ... [more ▼]

Electromagnetic fields are able to promote axonal regeneration in vitro and in vivo. Repetitive transcranial magnetic stimulation (rTMS) is used routinely in neuropsychiatric conditions and as an atraumatic method to activate descending motor pathways. After spinal cord injury, these pathways are disconnected from the spinal locomotor generator, resulting in most of the functional deficit. We have applied daily 10 Hz rTMS for 8 weeks immediately after an incomplete high (T4-5; n = 5) or low (T10-11; n = 6) thoracic closed spinal cord compression -injury in adult rats, using 6 high- and 6 low-lesioned non-stimulated animals as controls. Functional recovery of hindlimbs was assessed using the BBB locomotor rating scale. In the control group, the BBB score was significantly better from the 7th week post-injury in animals lesioned at T4-5 compared to those lesioned at T10-11. rTMS significantly improved locomotor recovery in T10-11-injured rats, but not in rats with a high thoracic injury. In rTMS-treated rats, there was significant positive correlation between final BBB score and grey matter density of serotonergic fibres in the spinal segment just caudal to the lesion. We propose that low thoracic lesions produce a greater functional deficit because they interfere with the locomotor centre and that rTMS is beneficial in such lesions because it activates this central pattern generator, presumably via descending serotonin pathways. The benefits of rTMS shown here suggest strongly that this non-invasive intervention strategy merits consideration for clinical trials in human paraplegics with low spinal cord lesions. (C) 2003 Wiley-Liss, Inc. [less ▲]

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See detailSerum selenium in lymphoma.
Beguin, Yves ULg; Weber, Georges ULg

in Journal of Clinical Oncology (2004), 22(16), 34293430

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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 detailUnequal Lovers at the laboratory. Non-destructive analyses of a sixteenth century Netherlandish painting
Oger, Cécile ULg; Allart, Dominique ULg; Fraiture, Pascale et al

in Townsend, Joyce; Eremin, Katherine; Adriaens, Annemie (Eds.) Conservation Science 2002. Papers from the Conference held in Edinburgh, Scotland 22-24 May 2002 (2003)

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See detailNon destructive analysis of a 16th manuscript from the Gospel Book of Robert Quercentius
Denoël, Sophie; Weber, Georges ULg; Allart, Dominique ULg et al

in Townsend, Joyce; Eremin, Katherine; Adriaens, Annemie (Eds.) Conservation Science 2002. Papers from the Conference held in Edinburgh, Scotland 22-24 May 2002 (2003)

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See detailArchéométrie et orfèvrerie. À propos de l'expertise d'argenteries liégeoises
George, Philippe ULg; Weber, Georges ULg; Martinot Lucien

in Dumortier, Jean-Louis; George, Philippe (Eds.) Regards sur le XVIIe siècle. Feuillets de la Cathédrale de Liège (2003)

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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 detailPIXE-identification of pigments used in old masters paintings : Black chalk used as a pigment in an oil painting attributed to Lambert Lombard (Liège 1506-1566)
Oger, Cécile ULg; Allart, Dominique ULg; Weber, Georges ULg

in Proceedings of Art 2002 7th International Conference on "Non-destructive Testing and Microanalysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage" (2002)

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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 detailArchéométrie et orfèvrerie mosane : émaux du Musée Curtius sous l’œil du cyclotron
George, Philippe ULg; Weber, Georges ULg; Martinot Lucien et al

in Bulletin de l'Institut Historique Liégeois (2001)

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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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See detailLa clé de saint Hubert, palladium de la cité épiscopale
George, Philippe ULg; Weber, Georges ULg; Martinot, Lucien

in Liège. Autour de l'an mil, la naissance d'une principauté (Xe-XIIe siècle) (2000)

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See detailCharacteristics of the iron moment in Dy-Fe and Dy-FeCo amorphous alloys studied by X-ray magnetic circular dichroism
Fleury-Frenette, Karl ULg; Dhesi, S. S.; van der Laan, G. et al

in Journal of Magnetism & Magnetic Materials (2000), 220(1), 45-51

The local magnetic moment of Fe in Dy-Fe and Dy-FeCo amorphous alloys has been studied using X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD). The Fe orbital and spin magnetic ... [more ▼]

The local magnetic moment of Fe in Dy-Fe and Dy-FeCo amorphous alloys has been studied using X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD). The Fe orbital and spin magnetic moments have been obtained for a range of alloy compositions by applying the sum rules to the XMCD spectra. The room temperature variations of the average components of the Fe moments as a function of Dy concentration and with the substitution of Fe by Co have been determined. A sharp reversal of the total magnetic moment was found at 28 +/- 1 at% Dy for both alloys. (C) 2000 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailIs the external beam PIXE method suitable for determining ancient silver artifact fineness?
Weber, Georges ULg; Guillaume, J.; Strivay, David ULg et al

in Nuclear Instruments & Methods in Physics Research Section B (2000), 161

In archeometry, the non-destructive characteristic of an analytical method is always very attractive. For most of techniques, besides the need of sampling, difficulties can originate from the shape and ... [more ▼]

In archeometry, the non-destructive characteristic of an analytical method is always very attractive. For most of techniques, besides the need of sampling, difficulties can originate from the shape and the size of the silver artifacts to be analyzed. The external PIXE method should be an answer to this problem but several questions are arising from the implementation of the technique to such a material. The aim of this paper is to specify the experimental procedure as to take into account several parameters, which could induce dramatic errors. Among them it can be pointed out the superficial enrichment in silver, arising from the dissolution of copper and copper oxide, the surface roughness effects, the great importance of the stability of the geometric conditions. The accuracy and the precision of the method are considered within the scope of the results obtained in ancient times by the cupellation with ashbone cupels. In addition. the process involved to obtain silver alloys has been studied in order to define its influence on the real fineness of the objects. (C) 2000 Elsevier Science B.V. All rights reserved. [less ▲]

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