Publications ORBi OA
Bookmark and Share    
Full Text
See detailControlled free-radical polymerization products using new controlled agents
Vanhoorne, Pierre; Meyer, Rolf-Volker; Detrembleur, Christophe ULg et al

Patent (2002)

The present invention relates to a new process for the production of polymers by means of pseudo-living free-radical polymerization using nitrogen monoxide, as well as to intermediate products and ... [more ▼]

The present invention relates to a new process for the production of polymers by means of pseudo-living free-radical polymerization using nitrogen monoxide, as well as to intermediate products and polymers obtainable by the process according to the invention and the use thereof. [less ▲]

Detailed reference viewed: 11 (5 ULg)
Full Text
Peer Reviewed
See detailSynthesis and compatibilization ability of hydrogenated polybutadiene-b-polyamide 6 diblock copolymer in low density polyethylene and polyamide 6 blends
Harrats, Charef; Fayt, R.; Jérôme, Robert ULg

in Polymer (2002), 43(19), 5347-5354

This paper describes the synthesis of hydrogenated polybutadiene-b-polyamide 6 (HPB-b-PA6), a pure diblock copolymer, which consists of three main steps: synthesis of hydroxyl terminated polybutadiene ... [more ▼]

This paper describes the synthesis of hydrogenated polybutadiene-b-polyamide 6 (HPB-b-PA6), a pure diblock copolymer, which consists of three main steps: synthesis of hydroxyl terminated polybutadiene, its hydrogenation and functionalization with an epsilon-caprolactam blocked diisocyanate. In a third step the functionalized HPB is copolymerized with epsilon-caprolactam monomer via ring opening anionic polymerization. The compatibilization ability of the synthesized pure diblock copolymer was evaluated in low-density polyethylene (LDPE)/polyamide 6 (PA6) blends. The investigation includes phase morphology development using both optical and electron scanning microscopy. The ultimate tensile properties of the modified and non-modified blends were also evaluated. The synthesized pure diblock copolymer exhibits very interesting interfacial activity both in terms of particle size reduction and improvement of the interfacial adhesion between the incompatible LDPE/PA6 phases. The tensile properties of the investigated blends were also significantly affected by the addition of the copolymer. The efficiency of compatibilization was found to be very sensitive to the molecular characteristics such as composition and molecular weight of the copolymer. Among the copolymers investigated a copolymer containing 24 wt% PA6 and having a total molecular weight (M) over bar (a) of 87,000 was found to exhibit the most efficient interfacial activity. [less ▲]

Detailed reference viewed: 29 (0 ULg)
Full Text
See detailDéveloppement et mise au point d’une boucle d’étalonnage pour vanne de régulation en vue d’une future accréditation
Caprace, Jean-David ULg

Master's dissertation (2002)

This project for the graduation of Mechanical Engineer has been realised in the Laboratory for Hydraulic Research of the Ministry of Equipment and Transport of Belgium. It consisted of the design and the ... [more ▼]

This project for the graduation of Mechanical Engineer has been realised in the Laboratory for Hydraulic Research of the Ministry of Equipment and Transport of Belgium. It consisted of the design and the realisation of a test bench for hydraulic control valves in preparation for qualified calibration (ISO 17025). Enventually measurement of actual flow characteristics will allow to optimise the use of valves in piping systems. The work has been done in several phases: design, study of metrology, study of standards, implementation and finally preliminary tests and results. The dimensioning of the test bench led to the drawings and draughts of all pipe sections and of the rejection canal (valves with diameter from 100 to 300 mm). The prssure drop has also been evaluated over the whole system. Concerning methodology, measuring techniques were identified, sensors and their signal handling units have been chosen and dimensioned: weirs, pressure sensor, torque meter and electromagnetic flow meter. With the aim to prepare the future qualification of the test bench, existing standards were identified and studied. Their recommendations have been applied where possible. Finally the test bench has been constructed, which has been a rich experience because of the many unexpected problems related to technique as well as to methodology. Preliminary test results for the calibration of a butterfly valve are promising. Nevertheless there is still some work to do before calibration can be qualified. Anyhow the data already collected and the many observations done during these tests were a good opportunity to analyse technological problems and standardisation. So this as a whole results in a data package which can be the base for future projects. [less ▲]

Detailed reference viewed: 80 (9 ULg)
Full Text
See detailEtude complémentaire relative aux profils d'accessibilité - profils de mobilité
Daxhelet, Delphine; Kessler, Laurent; Lambotte, Jean-Marc ULg et al

Report (2002)

Detailed reference viewed: 31 (10 ULg)
Full Text
Peer Reviewed
See detailTechniques for a selective encryption of uncompressed and compressed images
Van Droogenbroeck, Marc ULg; Benedett, Raphaël

in ACIVS Advanced Concepts for Intelligent Vision Systems, Proceedings (2002, September)

This paper describes several techniques to encrypt uncompressed and compressed images. We first present the aims of image encryption. In the usual ways to encryption, all the information is encrypted. But ... [more ▼]

This paper describes several techniques to encrypt uncompressed and compressed images. We first present the aims of image encryption. In the usual ways to encryption, all the information is encrypted. But this is not mandatory. In this paper we follow the principles of a technique initially proposed by MAPLES et al. [1] and encrypt only a part of the image content in order to be able to visualize the encrypted images, although not with full precision. This concept leads to techniques that can simultaneously provide security functions and an overall visual check which might be suitable in some applications like, for example, searching through a shared image database. The principle of selective encryption is first applied to uncompressed images. Then we propose a simple technique applicable to the particular case of JPEG images. This technique is proven not to interfere with the decoding process in the sense that it achieves a constant bit rate and that bitstreams remain compliant to the JPEG specifications. Then we develop a scheme called multiple selective encryption, discuss its properties and conclude. [less ▲]

Detailed reference viewed: 262 (7 ULg)
Full Text
See detailAnalysis of longitudinal data for selection and management
Gengler, Nicolas ULg; Mayeres, Patrick

in Book of Abstracts of the 53rd Annual Meeting of the European Association for Animal Production (2002, September)

Until recently the description of dynamic biological processes was done using static models even if those biological processes such as lactation or growth provided us with longitudinal data. A classical ... [more ▼]

Until recently the description of dynamic biological processes was done using static models even if those biological processes such as lactation or growth provided us with longitudinal data. A classical example was the use of lactational milk yields even if individual test-days describing the underlying lactation curves were available. Similarly for growth, weights were corrected phenotypically to fit into categories like weaning or yearling weights. Several recent developments stimulated the research on alternative methods describing the evolution of the mean and the variances of continuos dynamic biological processes. These developments were especially the extension of repeatability models towards random regressions and the development of the (co)variance function approach, but the development of better computers allowing the storage and the processing of a huge quantity of data. Despite this the analysis of certain types of longitudinal data as test-day yields in large populations and/or international settings is still a major challenge. But a very important aspect of the analysis of longitudinal data is often forgotten: they give us other information than the one classically extracted from genetic evaluation systems. In fact, the detailed modeling of dynamic biological processes provides opportunities for the development of advanced management tools. This may have a large influence on the way genetic evaluation systems may evolve in the future, making them integrated systems for the management and selection of animals. [less ▲]

Detailed reference viewed: 16 (3 ULg)
Full Text
Peer Reviewed
See detailThe OSIRIS Project (Optical Systems for Interferometric-Photogrammetric Relief Investigation and Scanning). Development of a device for 3D numerical recording of archaeological and epigraphic documents by optoelectronic processes
Laboury, Dimitri ULg; Renotte, Yvon ULg; Tilkens, Bernard et al

in Boehler, Wolfgang (Ed.) PROCEEDINGS OF THE CIPA WG 6 INTERNATIONAL WORKSHOP ON SCANNING FOR CULTURAL HERITAGE RECORDING (2002, September)

Detailed reference viewed: 87 (9 ULg)
Full Text
Peer Reviewed
See detailEchocardiographic evaluation of cardiac performance during stimulation with dobutamine in conscious horses: a preliminary study
Sandersen, Charlotte ULg; Delguste, Catherine ULg; Debrue, Marie et al

in Proceedings of the 41st Annual Congress of the British Equine Veterinairy Association (2002, September)

Detailed reference viewed: 12 (4 ULg)
Full Text
Peer Reviewed
See detailIn Vitro Susceptibility Testing of Aspergillus fumigatus against Posaconazole: Comparison of NCCLS M38-P and E-Test Methods
Hayette, Marie-Pierre ULg; Amadore, Agatha; Seidel, Laurence ULg et al

Poster (2002, September)

Posaconazole is a second-generation triazole and structural analogue of itraconazole. This drug has fungicidal activity against yeasts and filamentous fungi. The aim of our study was to evaluate E-test ... [more ▼]

Posaconazole is a second-generation triazole and structural analogue of itraconazole. This drug has fungicidal activity against yeasts and filamentous fungi. The aim of our study was to evaluate E-test method for in vitro susceptibility testing of Aspergillus fumigatus isolates against posaconazole. METHODS: A total of 121 isolates of A. fumigatus were selected as follows: 106 clinical strains from colonized patients, 18 from patients with invasive aspergillosis and 7 environmental isolates. Their in vitro susceptibility was evaluated by E-test (Abbiodisk, Sweden) and compared with NCCLS microdilution reference method (M38-P). Both tests were performed with RPMI 1640 medium at 35 degrees C. MIC values were read after 24h (MIC-24h) and 48h (MIC-48h) incubation time by E-test method. Two MIC endpoints were determined by NCCLS method: 1.no visible reduction of growth (MIC-0); 2. 50% reduction (or more) of growth (MIC-2). Three A. fumigatus reference strains (IHEM 5734, 6149 and 13935) were included as control. RESULTS: Geometric mean MICs (microg/ml) were respectively 0.02 for E-test at 24h and 0.029 at 48h. MIC-0 and MIC-2 values were respectively 0.19 and 0.018 microg/ml. One correlation between both methods was observed for MICs-24h and MICs-2s (p<.05). However, there was no significant difference according to origin of isolates (p<.05). CONCLUSIONS: 1. This study assessed the potent role of posaconazole against A. fumigatus isolates with very low MICs. 2. MIC values were not predictive of pathogenicity. 3. E-test method by reading after 24h-incubation time could easily replace the time-consuming NCCLS M38-P reference method. [less ▲]

Detailed reference viewed: 32 (0 ULg)
Full Text
Peer Reviewed
See detailLa fenetre implantatoire
Perrier D'Hauterive, Sophie ULg; Charlet, Jeanne de Chantal ULg; Goffin, Frédéric ULg et al

in Journal de Gynécologie, Obstétrique et Biologie de la Reproduction (2002), 31(5), 440-55

BACKGROUND: Embryo implantation is a complex event involving apposition followed by adhesion of the blastocyst to the maternal endometrium, and finally invasion of this endometrium. Though implantation ... [more ▼]

BACKGROUND: Embryo implantation is a complex event involving apposition followed by adhesion of the blastocyst to the maternal endometrium, and finally invasion of this endometrium. Though implantation could occur in any human tissue, the endometrium is the only tissue where embryo implantation cannot occur except during a restricted period called the implantation window. During this window, the endometrium is highly receptive to the embryo. MATERIAL: and methods. We reviewed the literature concerning the different factors involved in improved endometrial receptivity and implantation. RESULTS: Maternal - embryo crosstalk is favored by the implantation window. Endometrial receptivity results from the acquisition of ligands or receptors facilitating apposition, then adhesion of the embryo, or from the loss of components preventing it. The molecular basis of the implantation window remains to be defined. CONCLUSION: Despite progress in assisted reproduction technologies, the lack of control of implantation remains a major obstacle to successful pregnancy. It is of prime importance to determine the characteristic features of a receptive endometrium and, among the many markers proposed by in vitro studies, to analyze in humans those demonstrated by knock-out experiments to play a crucial role in mice. [less ▲]

Detailed reference viewed: 54 (3 ULg)
Full Text
Peer Reviewed
See detailOntogenetic variations of thermal optimum for growth, and its implication on thermolabile sex determination in blue tilapia
Baras, E.; Mpo'n'tcha, A.; Driouch, H. et al

in Journal of Fish Biology (2002), 61(3), 645-660

Knowledge of how the optimum temperature for growth (Tdegrees(opt)) varies during ontogeny, and how close it is to the temperatures that induce Phenotypic masculinization is fundamental to the ... [more ▼]

Knowledge of how the optimum temperature for growth (Tdegrees(opt)) varies during ontogeny, and how close it is to the temperatures that induce Phenotypic masculinization is fundamental to the understanding of the evolution of thermolabile sex determinism (TSD) in fishes. In blue tilapia Oreochromis aureus, Tdegrees(opt) is 32.6degrees C at the start of exogenous feeding (10 mg fish) and it decreases by c 1degrees C each time that the fish bode mass increases by an order of magnitude. Temperatures <35degrees C are not sufficient to induce complete phenotypic masculinization. Based on a multiple-regression model (r(2)=0.938) plotting growth against body mass and water temperature. genotypically female tilapia living at high temperatures during the thermosensitive period (21-28 days) and being reversed into phenotypic males should incur an initial growth disadvantage over fish living at Tdegrees(opt) but not over those living at slightly colder temperatures (27-29degrees C). This initial disadvantage would be later compensated for by faster growth because of between-sex growth dimorphism to the detriment of phenotypic females. These arguments suggest that there is no definite pressure against the selection of TSD in blue tilapia and probable other Oreochromis spp. (C) 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 24 (2 ULg)
Full Text
Peer Reviewed
See detailIndexation et organisation de la connaissance. La régulation des décisions sur un forum de discussion
Lejeune, Christophe ULg

in Cahiers du Numérique (2002), 3(2), 129-144

This article presents the problems lived by a team of indexers organized in network that coordinates its activities by using discussion forum. The author aim to follow the coding problem solving that ... [more ▼]

This article presents the problems lived by a team of indexers organized in network that coordinates its activities by using discussion forum. The author aim to follow the coding problem solving that occurs in this project. The ongoing achievement of indexation raises up the question of the social, cognitive, political and quantitative representation and leads actors to compose associations’ networks (between sources of information, keywords, databases and indexers). The willing to collaborate and to communicate constraints them to coordinate and find agreement; discussions show the diverse and unstable forms of agreement processes. [less ▲]

Detailed reference viewed: 233 (38 ULg)
Full Text
See detailMaladie du hêtre. Bilan chiffré de la situation à l'été 2001
Rondeux, Jacques ULg; Bourland, Nils ULg; Huart, O. et al

in Forêt Wallonne (2002), (60), 2-3

Durant l'été 2001, un inventaire des dégâts occasionnés par la maladie du hêtre à été réalisé. Les résultats de cette étude ont été publiés dans la revue Silva belgica. Nous en reprenons ici la conclusion ... [more ▼]

Durant l'été 2001, un inventaire des dégâts occasionnés par la maladie du hêtre à été réalisé. Les résultats de cette étude ont été publiés dans la revue Silva belgica. Nous en reprenons ici la conclusion ainsi que quelques-uns des nombreux graphiques et tableaux qui y sont présentés. Nous invitons le lecteur intéressé à se référer à l'article original. [less ▲]

Detailed reference viewed: 28 (9 ULg)
Full Text
Peer Reviewed
See detailSerotype Distribution of clinical isolates of group B streptococci Isolated in Belgium : isolates from neonatal infection compared to isolates from infection in adult or colonization in pregnant women
MELIN, Pierrette ULg; Keke, D.; Campo, B. et al

in American Society of Microbiology (Ed.) Program and Abstracts of the 43rd Intersciences Conference on Antimicrobial Agents and Chemotherapy (2002, September)

Background: Group B Streptococci cause invasive disease in neonates, pregnant women and non-pregnant adults. In the last decades capsular serotypes (type) Ia, Ib, II and III caused the majority of ... [more ▼]

Background: Group B Streptococci cause invasive disease in neonates, pregnant women and non-pregnant adults. In the last decades capsular serotypes (type) Ia, Ib, II and III caused the majority of clinical diseases. More recently, in North America, type V emerged as the more common type in non-pregnant adults with invasive disease. Methods: From January 1999 through December 2001, we received and typed a total of 334 clinically significant strains of GBS isolated in the laboratories belonging to the Belgian network for epidemiological surveillance. 113 were recovered from neonates blood or cerebrospinal fluid (92 early onset EOD, 21 late onset LOD), 14 were isolated from pregnant women with severe infections and 204 were recovered from adults with invasive disease. From the same laboratories, during the first trimester of 2002, 302 isolates from pregnant women were also typed (max. 5 isolates /lab.) Results: In neonatal EOD type III was the more common (41,3%) followed by II (19.6%), Ia (16.3%), Ib (13%), V (8.7%) and IV (1.1%), whereas type III caused the majority (85.7%) of LOD cases. In adults, all types were well represented except type IV: 20.3% Ia, 12.7% Ib, 13.1% II, 23.1% III, 2.7% IV, 19% V and 9% remained non typeable (NT). In colonized pregnant women, all types were also well represented except type IV: 25.5% Ia, 13.3% Ib, 14.9% II, 17.7% III, 5% IV, 15.5% V and 8.1% remained NT. Type III was more frequently the cause of EOD than a colonizing strain during pregnancy and in contrast NT isolates did not cause EOD (P<0.001) Conclusions: 1) Type III was still the major type in neonatal infections in Belgium. 2) Type distribution of GBS differed by age-group of patients 3) Type V belonged to the 3 more represented types in adults 4) Compared to colonizing GBS in pregnant women, distribution of types causing EOD was different. [less ▲]

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
See detailAccelerated postoperative radiation therapy with weekly concomitant boost in high risk patients with squamous-cell carcinoma of the head and neck
Chevalier; Pasche; COUCKE, Philippe ULg et al

in Radiotherapy & Oncology (2002), 64(supp 1), 248

Detailed reference viewed: 8 (1 ULg)
Full Text
Peer Reviewed
See detailDevelopment and in vitro characterisation of novel bioresorbable and bioactive composite materials based on polylactide foams and Bioglass (R) for tissue engineering applications
Roether, J. A.; Boccaccini, Aldo R.; Hench, L. L. et al

in Biomaterials (2002), 23(18), 3871-3878

Bioactive and bioresorbable composite materials were fabricated using macroporous poly(DL-lactide) (PDLLA) foams coated with and impregnated by bioactive glass (Bioglass®) particles. Stable and ... [more ▼]

Bioactive and bioresorbable composite materials were fabricated using macroporous poly(DL-lactide) (PDLLA) foams coated with and impregnated by bioactive glass (Bioglass®) particles. Stable and homogeneous Bioglasss coatings on the surface of PDLLA foams as well as infiltration of Bioglass® particles throughout the porous network were achieved using a slurry-dipping technique in conjunction with pre-treatment of the foams in ethanol. The quality of the bioactive glass coatings was reproducible in terms of thickness and microstructure. Additionally, electrophoretic deposition was investigated as an alternative method for the fabrication of PDLLA foam/Bioglass® composite materials. In vitro studies in simulated body fluid (SBF) were performed to study the formation of hydroxyapatite (HA) on the surface of PDLLA/Bioglass® composites. SEM analysis showed that the HA layer thickness rapidly increased with increasing time in SBF. The high bioactivity of the PDLLA foam/Bioglasss composites indicates the potential of the materials for use as bioactive, resorbable scaffolds in bone tissue engineering. [less ▲]

Detailed reference viewed: 65 (3 ULg)
Full Text
See detailOn the exploitation of chaos to build reduced-order models
Kerschen, Gaëtan ULg; Feeny, B. F.; Golinval, Jean-Claude ULg

in International Conference on Noise and Vibration Engineering, Leuven, 2002 (2002, September)

The present study focuses on the model reduction of non-linear systems. The proper orthogonal decomposition is exploited to compute eigenmodes from time series of displacement. These eigenmodes, called ... [more ▼]

The present study focuses on the model reduction of non-linear systems. The proper orthogonal decomposition is exploited to compute eigenmodes from time series of displacement. These eigenmodes, called the proper orthogonal modes, are optimal with respect to energy content and are used to build a low-dimensional model of the non-linear system. For this purpose, the proper orthogonal modes obtained from a chaotic orbit are considered. Indeed, such an orbit is assumed to cover the phase space more uniformly. It is shown that the modes for this particular behaviour are more representative of the system dynamics than any other set of modes extracted from a non-chaotic response. This is applied to a buckled beam with two permanent magnets and the reduced-order model is validated using both qualitative and quantitative comparisons. [less ▲]

Detailed reference viewed: 9 (0 ULg)