References of "Weber, Georges"
     in
Bookmark and Share    
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 15 (3 ULg)
Full Text
Peer Reviewed
See detailStudy of the mechanism of direct laser desorption/ionisation for some small organic molecules (M < 400 daltons)
Benazouz, M.; Hakim, B.; Debrun, J. L. et al

in Rapid Communications in Mass Spectrometry : RCM (1999), 13(23), 2302-2304

Aspects of direct laser desorption/ionisation have been studied for three molecules, aminotriazole (positive ion), dinoterb and ioxynil (negative ion). The samples are deposited on metallic substrates ... [more ▼]

Aspects of direct laser desorption/ionisation have been studied for three molecules, aminotriazole (positive ion), dinoterb and ioxynil (negative ion). The samples are deposited on metallic substrates, and a nitrogen laser is used for desorption/ionisation; ion yields are measured with a time-of-flight mass spectrometer, Previous work had shown that ion yields can strongly vary from one substrate to another, and that this variation does not reflect the (calculated) metal surface temperatures. New results obtained in this work indicate that the desorption/ionisation mechanism is linked to the physical state of the substrate surface. Copyright (C) 1999 John Wiley & Sons, Ltd. [less ▲]

Detailed reference viewed: 8 (1 ULg)
Full Text
Peer Reviewed
See detailBronchial Responsiveness in Active Steelworkers
Corhay, Jean-Louis ULg; Bury, Thierry ULg; Louis, Renaud ULg et al

in European Respiratory Journal (1998), 11(2), 272-7

Coke-oven workers are exposed to dust and irritant gases. Therefore they are at risk of developing lung diseases including chronic bronchitis. Nonspecific bronchial hyperresponsiveness (BHR) has been ... [more ▼]

Coke-oven workers are exposed to dust and irritant gases. Therefore they are at risk of developing lung diseases including chronic bronchitis. Nonspecific bronchial hyperresponsiveness (BHR) has been advocated as a potential risk factor predisposing to the development of chronic bronchitis. In a previous study, we showed that prevalence of BHR was higher in retired coke-oven workers than in retired blast furnace workers. The present study was carried out to determine the prevalence of BHR in active steelworkers. Thus, 137 coke-oven workers and 150 blast furnace workers underwent clinical examination, a standardized questionnaire for the study of respiratory symptoms, pulmonary function testing and methacholine aerosol challenge. The study demonstrates a higher prevalence and degree of BHR [provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (PC20) < or = 8 mg x mL(-1)] in coke-oven workers than in blast furnace workers (31.4 versus 6.7%; p<0.001). Moreover, the frequency of respiratory symptoms and basal bronchial obstruction were greater among coke-oven workers with BHR in nonresponders. The basal maximum expiratory flow from 25-75% of forced vital capacity and the respiratory symptoms were correlated with bronchial responsiveness. The lack of correlation observed between BHR and the intensity of smoking or years spent in coke-oven environment may be explained by the high proportion of smokers, the worker turnover in the steel plant, and the "healthy worker effect". In conclusion, the higher prevalence and degree of bronchial hyperresponsiveness in coke-oven workers suggests that coke-oven pollutants are more intense irritants than those that escape from blast furnaces. [less ▲]

Detailed reference viewed: 23 (6 ULg)
Full Text
Peer Reviewed
See detailControlled exchange of metallic cations by a polypyrrole-based resin
Jérôme, Christine ULg; Martinot, Lucien; Jérôme, Robert ULg et al

in Journal de Chimie Physique et de Physico-Chimie Biologique (1998), 95(6), 1475-1478

This work shows that the binding and the release of Cs+, Ba2+, La3+ and Th4+ cations can be controlled by the application of a potential to a polypyπole doped with polystyrene sulfonate exchange-resin ... [more ▼]

This work shows that the binding and the release of Cs+, Ba2+, La3+ and Th4+ cations can be controlled by the application of a potential to a polypyπole doped with polystyrene sulfonate exchange-resin. Radiometric and nuclear techniques were carried out to characterize the reversibility of the process in relation with the exchanged-cation charge. [less ▲]

Detailed reference viewed: 28 (8 ULg)
Full Text
Peer Reviewed
See detailQuantification by PIXE of metallic sites in proteins separated by electrophoresis
Strivay, David ULg; Schoefs, B.; Weber, Georges ULg

in Nuclear Instruments & Methods in Physics Research Section B (1998), 137

Electrophoresis on polyacrylamide gel (PAGE) is widely used in life sciences to determine the molecular weight of proteins in solution by separating them into different bands. By coupling electrophoresis ... [more ▼]

Electrophoresis on polyacrylamide gel (PAGE) is widely used in life sciences to determine the molecular weight of proteins in solution by separating them into different bands. By coupling electrophoresis and Particle Induced W-ray Emission (PIXE), the nature and the quantity of metals contained in proteins can be investigated. After the electrophoresis, the gel is dried and each track is scanned with a 2.5 MeV proton beam which induces X-ray emission. Analysis of these spectra allows the determination of the metals contained in an electrophoretic band. The metal content in each band is obtained by comparing the characteristic X-ray peak area with those obtained with polyacrylamide gels doped with the same metal. Finally, the relative concentration of each protein is determined by densitometry in order to compute the protein/metal ratio. An example of metallic site determination is presented. This procedure seems to be a very useful multielementary method for the determination of the metal amounts inside proteins after their separation by electrophoresis. Furthermore it allows to check if metals remain bound to proteins. (C) 1998 Elsevier Science B.V. [less ▲]

Detailed reference viewed: 7 (1 ULg)
Full Text
Peer Reviewed
See detailUse of a variable incidence angle PIXE arrangement for studying pigment multilayers
Weber, Georges ULg; Delbrouck, J. M.; Strivay, David ULg et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (1998), 139(1-4), 196-201

Particle induced X-ray emission (PIXE) method is used in the field of archeometry and specially to investigate pigment colored multilayers. The tilting of the sample with respect to the incident proton ... [more ▼]

Particle induced X-ray emission (PIXE) method is used in the field of archeometry and specially to investigate pigment colored multilayers. The tilting of the sample with respect to the incident proton beam direction allows to modify the relative contribution of each layer to the fluorescence signal. The experimental results coupled to computer simulations lead to semi-quantitative information about the thickness, the position and the composition of the successive layers. (C) 1998 Elsevier Science B.V. [less ▲]

Detailed reference viewed: 3 (0 ULg)
Full Text
Peer Reviewed
See detailAcute Functional Iron Deficiency in Obese Subjects During a Very-Low-Energy All-Protein Diet
Beguin, Yves ULg; Grek, Vincent; Weber, Georges ULg et al

in American Journal of Clinical Nutrition (1997), 66(1), 75-9

We examined whether a very-low-energy all-protein diet (VLED) would produce detectable changes in iron as well as in other trace elements. Twenty-five obese patients consumed for 2 wk a VLED containing 70 ... [more ▼]

We examined whether a very-low-energy all-protein diet (VLED) would produce detectable changes in iron as well as in other trace elements. Twenty-five obese patients consumed for 2 wk a VLED containing 70 g protein after a 1-wk period during which total daily energy intake was progressively reduced to 1.26 MJ. Serum iron fell sharply by approximately equal to 50% (P < 0.0001), and despite a small decrease in total-iron-binding capacity, transferrin saturation decreased from 30 +/- 11% to 18 +/- 5% (P < 0.0001). Serum ferritin did not change significantly but serum soluble transferrin receptor (sTfR), an indicator of iron deficiency, increased progressively from 4630 +/- 1110 to 6070 +/- 1390 micrograms/L (P < 0.0001). Changes in sTfR correlated inversely with prior changes in serum iron. Changes in iron metabolism did not translate into changes in erythropoiesis or red cell indexes, but the white blood cell count decreased from 7.3 +/- 1.6 to 6.2 +/- 1.9 x 10(9)/L (P < 0.002). There was no evidence of deficiency for the other trace elements and minerals tested. Daily supplementation with 200 mg Fe in 18 other subjects only partially corrected these observations despite some increase in iron stores. These results indicate that during a 2-wk VLED serum iron is significantly depressed, inducing functional tissue iron deficiency too short in duration to produce alterations in red blood cell indexes. These changes are not mediated by absolute iron deficiency, inflammation, or protein malnutrition but could be related to alterations in the iron storage and release behavior of the reticuloendothelial cell during energy deprivation alone. [less ▲]

Detailed reference viewed: 60 (11 ULg)
Full Text
Peer Reviewed
See detailAutomatic external filling for the ion source gas bottle of a Van de Graaff accelerator
Bastin, Thierry ULg; Dehove, C.; Dumont, Paul-Dominique ULg et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (1997), 129

We describe a fully automatic system we developed to fill, from an external gas bottle, the ion sourer terminal gas storage bottle of a 2 MV Van de Graaff accelerator without depressing the 25 bar ... [more ▼]

We describe a fully automatic system we developed to fill, from an external gas bottle, the ion sourer terminal gas storage bottle of a 2 MV Van de Graaff accelerator without depressing the 25 bar insulating gas. The system is based on a programmable automate ordering electropneumatical valves. The only manual operation is the connection of the external gas cylinder. The time needed for a gas change is reduced to typically 15 min (depending on the residual pressure wished for the gas removed from the terminal bottle). To check this system we study the ionic composition of the ion beam delivered by our accelerator after different gas changes. The switching magnet of our accelerator was used to analyse the ionic composition of the accelerated beams in order to verify the degree of elimination of the previous gases in the system. (C) 1997 Elsevier Science B.V. [less ▲]

Detailed reference viewed: 33 (8 ULg)
Full Text
Peer Reviewed
See detailQuantitative measurement of metal ions concentration of proteins separated by electrophoresis
Weber, Georges ULg; Strivay, David ULg; Menendez, M. et al

in International Journal of PIXE (1996), 1-2

This communication is devoted to nature determination and quantification by PIXE of metals contained in proteins after their separation by PolyAcrylamide Gel Electrophoresis (PAGE). After the ... [more ▼]

This communication is devoted to nature determination and quantification by PIXE of metals contained in proteins after their separation by PolyAcrylamide Gel Electrophoresis (PAGE). After the electrophoresis, the gel is dried and each track is scanned with a 2.5 MeV proton beam which triggers metal X-ray fluorescence and then, allows to determine the type of metals contained in an electrophoretic band. For quantitative determination of the amount of the metal contained inside the band, the characteristic X-ray peak area is compared with those obtained with polyacrylamide gels doped with the same metal. The normalization has been achieved by using RBS measurements on the gel itself. The procedure presented seems to be a very useful multielementary method for the metal content analysis and for the determination of the metal amounts inside proteins after their separation by electrophoresis. Furthermore it allows to check if metals remain bound to proteins. [less ▲]

Detailed reference viewed: 28 (1 ULg)
Peer Reviewed
See detailNonfibrous mineralogical analysis of bronchoalveolar lavage fluid from blast-furnace workers.
CORHAY, Jean-Louis ULg; Bury, Thierry ULg; Delavignette, Jean-Paul ULg et al

in Archives of Environmental Health (1995), 50(4), 312-9

Steelworkers are exposed to many pollutants, and they are at risk for developing lung cancer. We demonstrated previously that steelworkers may be subject to an occult exposure to amphiboles in the plant ... [more ▼]

Steelworkers are exposed to many pollutants, and they are at risk for developing lung cancer. We demonstrated previously that steelworkers may be subject to an occult exposure to amphiboles in the plant environment. In the current study, we further analyzed bronchoalveolar lavage fluid of steelworkers by measuring intramacrophagic trace-metal content and nonfibrous mineral particles, using the particle-induced x-ray emission method and electron microscopy, respectively. Forty-seven blast-furnace workers and 45 healthy white-collar workers volunteered for this study. Significantly increased levels of iron, titanium, zinc, and bromine were found in the steelworkers, and levels of lead, chromium, arsenic, and strontium tended to increase in the macrophages and bronchoalveolar lavage fluid of the steelworkers. Nonfibrous particles, including illite, kaolinite, talc, chlorite, amorphous silica, quartz, iron (compounds), and titanium hydroxide, were found in both groups, but the particle number per ml bronchoalveolar lavage fluid (particularly iron hydroxides and silicates) was more pronounced in blast-furnace workers. These elements and particles may act synergistically with other occupational carcinogens and cigarette smoke, the result of which may be an increased incidence of lung cancer in the ironsteel industry. [less ▲]

Detailed reference viewed: 7 (2 ULg)
Peer Reviewed
See detailLa clé de saint Hubert
George, Philippe ULg; Weber, Georges ULg; martinot lucien

in Feuillets de la Cathédrale de Liège (1995)

Detailed reference viewed: 5 (0 ULg)
Full Text
Peer Reviewed
See detailCharacterization of the Sporulation-Related Gamma-D-Glutamyl-(L)Meso-Diaminopimelic-Acid-Hydrolysing Peptidase I of Bacillus Sphaericus NCTC 9602 as a Member of the Metallo(Zinc) Carboxypeptidase A Family. Modular Design of the Protein
Hourdou, Marie-Laure; Guinand, Micheline; Vacheron, Marie-Jeanne et al

in Biochemical Journal (1993), 292(Pt 2), 563-570

The sporulation-related gamma-D-glutamyl-(L)meso-diaminopimelic-acid-hydrolysing peptidase I of Bacillus sphaericus NCTC 9602 has been analysed by proton-induced X-ray emission. It contains 1 equivalent ... [more ▼]

The sporulation-related gamma-D-glutamyl-(L)meso-diaminopimelic-acid-hydrolysing peptidase I of Bacillus sphaericus NCTC 9602 has been analysed by proton-induced X-ray emission. It contains 1 equivalent Zn2+ per mol of protein. As derived from gene cloning and sequencing, the B. sphaericus Zn peptidase I is a two-module protein. A 100-amino-acid-residue N-terminal domain consisting of two tandem segments of similar sequences, is fused to a 296-amino-acid-residue C-terminal catalytic domain. The catalytic domain belongs to the Zn carboxypeptidase A family, the closest match being observed with the Streptomyces griseus carboxypeptidase [Narahashi (1990) J. Biochem. 107, 879-886] and with the family prototype, bovine carboxypeptidase A. The catalytic domain of the B. sphaericus peptidase I possesses, distributed along the amino-acid sequence, peptide segments, a triad His162-Glu165-His307 and a dyad Tyr347-Glu366 that are equivalent to secondary structures, the zinc-binding triad His69-Glu72-His196 and the catalytic dyad Tyr248-Glu270 of bovine carboxypeptidase A respectively. The N-terminal repeats of the B. sphaericus peptidase I have similarity with the C-terminal repeats of the Enterococcus hirae muramidase 2, the Streptococcus (now Enterococcus) faecalis autolysin and the Bacillus phi PZA and phi 29 lysozymes, to which a role in the recognition of a particular moiety of the bacterial cell envelope has been tentatively assigned. Detergents enhance considerably the specific activity of the B. sphaericus peptidase I. [less ▲]

Detailed reference viewed: 39 (4 ULg)
Peer Reviewed
See detailIron content in human alveolar macrophages.
CORHAY, Jean-Louis ULg; Weber, Georges ULg; Bury, Thierry ULg et al

in European Respiratory Journal (1992), 5(7), 804-9

Intracellular iron can be estimated semi-quantitatively by histochemical determination using the ferrocyanide reagent's score. Particle-induced X-ray emission (PIXE) allows accurate determination of ... [more ▼]

Intracellular iron can be estimated semi-quantitatively by histochemical determination using the ferrocyanide reagent's score. Particle-induced X-ray emission (PIXE) allows accurate determination of various elements including iron in cells and biological fluids. Both techniques have been used to measure iron in alveolar macrophages gathered by bronchoalveolar lavage. The purpose of this study was to investigate the clinical usefulness of the PIXE technique in occupational respiratory medicine and in various pulmonary diseases. Using the PIXE method, we measured the iron content of alveolar macrophages in healthy subjects, with and without occupational exposure to iron dust, and in patients with pulmonary diseases (chronic obstructive pulmonary disease (COPD), lung cancer, Goodpasture's syndrome). Our results were then compared with those obtained with the ferrocyanide reagent. Intramacrophagic iron was 0.33 +/- 0.21 micrograms.10(-6) (mean +/- SD) cells in healthy non-smoking subjects without occupational exposure. Intramacrophagic iron was increased in smokers, iron-steelworkers, and in patients with COPD or lung cancer even in the absence of pulmonary haemorrhage. The two patients with Goodpasture's syndrome had high intramacrophagic iron content. About 80% of the whole bronchoalveolar lavage fluid iron content was in the cells. Mean iron content of blood monocytes, lymphocytes and neutrophils of eight healthy subjects was significantly lower than that of alveolar macrophages. A significant correlation was found between iron determination by the PIXE method and the ferrocyanide reagent's score (r = 0.89). We conclude that intramacrophagic iron may be increased in steelworkers and subjects with pulmonary haemorrhage, but also in asymptomatic smokers, in COPD and lung cancer patients without occupational exposure to iron dust. [less ▲]

Detailed reference viewed: 11 (0 ULg)
Peer Reviewed
See detailRelationship of Serum Selenium Levels to Tumor Activity in Acute Non-Lymphocytic Leukemia
Beguin, Yves ULg; Bours, Vincent ULg; Delbrouck, J. M. et al

in Carcinogenesis (1989), 10(11), 2089-91

Serum selenium (Se) levels were measured before, during and after high-dose induction chemotherapy in 70 patients with acute non-lymphocytic leukemia (ANLL). Pre-treatment serum Se levels were lower in ... [more ▼]

Serum selenium (Se) levels were measured before, during and after high-dose induction chemotherapy in 70 patients with acute non-lymphocytic leukemia (ANLL). Pre-treatment serum Se levels were lower in patients than in controls (0.082 +/- 0.033 micrograms/ml versus 0.097 +/- 0.035 micrograms/ml, P less than 0.01). Pretreatment serum Se correlated inversely with the absolute peripheral blast cell count (R = -0.62, P less than 0.001) and other measurements of the tumor burden. Seven days after the initiation of chemotherapy, serum Se increased significantly in proportion to the initial tumor burden (P less than 0.01). Thereafter, serum Se levels remained essentially normal in patients entering a complete remission while decreasing gradually in failures. In conclusion, these data do not lend support to the hypothesis that a low selenium status enhances the risk of developing ANLL, but indicate that serum Se levels in patients with acute leukemia are mostly dependent on tumor activity. [less ▲]

Detailed reference viewed: 28 (19 ULg)
Full Text
Peer Reviewed
See detailUse of liposomes to reduce enhancement-absorption effects in PIXE
Robaye, G.; Weber, Georges ULg; Delbrouck-Habaru, J.-M. et al

in Nuclear Instruments & Methods (1980), 172(3), 535-9

It is demonstrated that enhancement-absorption effects which perturb the quantitative feature of PIXE can be lowered by using liposomes (synthetic phospholipid bilayer vesicles) as homogenizers in the ... [more ▼]

It is demonstrated that enhancement-absorption effects which perturb the quantitative feature of PIXE can be lowered by using liposomes (synthetic phospholipid bilayer vesicles) as homogenizers in the preparation of thin targets; [less ▲]

Detailed reference viewed: 5 (2 ULg)
Full Text
Peer Reviewed
See detailBiomedical application of PIXE in University of LIEGE
Weber, Georges ULg; Robaye G; Delbrouck JM et al

in Nuclear Instruments and Methods (1980), 168

Three biomedical applications of charged particle induced X-ray emission spectroscopy (PIXE) are outlined. The different fields investigated include biophysics (protein study), cancer chemotherapy (cis ... [more ▼]

Three biomedical applications of charged particle induced X-ray emission spectroscopy (PIXE) are outlined. The different fields investigated include biophysics (protein study), cancer chemotherapy (cis-dichlorodiamineplatinum (II) associated to liposomes as carriers) and lung pathology (serum and bronchio-alveolar lavages). The samples were irradiated with 3 Me V protons (cyclotron) in a nitrogen atmosphere. [less ▲]

Detailed reference viewed: 15 (1 ULg)