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See detailPolyethylene-layered silicate nanocomposites prepared by the polymerization-filling technique: synthesis and mechanical properties
Alexandre, Michaël ULg; Dubois, Philippe ULg; Sun, Tao et al

in Polymer (2002), 43(8), 2123-2132

Polyethylene-layered silicate nanocomposites were prepared by the in situ intercalative polymerization of ethylene by the so-called polymerization-filling technique and analyzed by transmission electron ... [more ▼]

Polyethylene-layered silicate nanocomposites were prepared by the in situ intercalative polymerization of ethylene by the so-called polymerization-filling technique and analyzed by transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), differential scanning calorimetry, dynamic mechanical analysis and tensile testing. Non-modified montmorillonite and hectorite were first treated by trimethylaluminum-depleted methylaluminoxane before being contacted by a Ti-based constrained geometry catalyst. The nanocomposite was formed by addition and polymerization of ethylene. In the absence of a chain transfer agent, ultra high molecular weight polyethylene was produced. The tensile properties of these nanocomposites were poor and essentially independent of the nature and content of the silicate. Upon hydrogen addition, the molecular weight of the polyethylene was decreased with parallel improvement of the tensile and shear moduli, in relation to the filler content. The exfoliation of the layered silicates was confirmed by XRD analysis and TEM observation. The mechanical kneading of the molten nanocomposites resulted in the partial collapse of the exfoliated structure driven by the thermodynamic stability of the layered filler. [less ▲]

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See detailL'EAD au service d'une approche centrée sur l'apprenant et sur la médiatisation de l'expérience
Georges, François ULg; Demily, Fabian; Leclercq, Dieudonné ULg et al

(2002, April)

Le Laboratoire de Soutien à l’Enseignement Télématique (LabSET, directrice : M. Poumay) a, entre autres, pour mission d’aider les enseignants et les formateurs à concevoir et à développer leurs cours et ... [more ▼]

Le Laboratoire de Soutien à l’Enseignement Télématique (LabSET, directrice : M. Poumay) a, entre autres, pour mission d’aider les enseignants et les formateurs à concevoir et à développer leurs cours et activités sur Internet. Nous travaillons non seulement avec des institutions d’enseignement supérieur (Université et Hautes Ecoles), mais aussi avec des centres de formation, des centres de compétences, des organismes d’insertion socio-professionnelle et des fédérations d’entreprises. Ces partenariats ont dernièrement fait l’objet de deux projets : Technifutur, du nom de son commanditaire, et FORMADIS subsidié par la Communauté Européenne, le Ministère de l’emploi et de la formation de la région wallonne et le Ministère de l’enseignement supérieur de la Communauté Française de Belgique. L'article décrit ces initiatives. [less ▲]

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See detailComparison of different impulse response measurement techniques
Stan, Guy-Bart; Embrechts, Jean-Jacques ULg; Archambeau, Dominique

in Journal of the Audio Engineering Society (2002), 50(4), 249-262

The impulse response of an acoustical space or transducer is one of its most important characterizations. In order to perform the measurement of their impulse responses, four of the most suitable methods ... [more ▼]

The impulse response of an acoustical space or transducer is one of its most important characterizations. In order to perform the measurement of their impulse responses, four of the most suitable methods are compared: MLS (maximum-length sequence), IRS (inverse repeated sequence), time-stretched pulses, and SineSweep. These methods have already been described in the literature. Nevertheless, the choice of one of them depending on the measurement conditions is critical. Therefore an extensive comparison has been realized. This comparison was done through the implementation and realization of a complete, fast, reliable, and cheap measurement system. Finally, a conclusion for the use of each method according to the principal measurement conditions is presented. It is shown that in the presence of nonwhite noise, the MLS and IRS techniques seem to be more accurate. On the contrary, in quiet environments the logarithmic SineSweep method seems to be the most appropriate. [less ▲]

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See detailLes logiques participatives dans le cadre du parcours d'insertion
Jacquemain, Marc ULg; Carpentier, Dominique

Conference (2002, April)

Le document décrit une intervention sociologique de près de deux années visant à mettre sur pied un dispositif participatif dans le cadre du "parcours d'insertion" des chômeurs en formation. Il s ... [more ▼]

Le document décrit une intervention sociologique de près de deux années visant à mettre sur pied un dispositif participatif dans le cadre du "parcours d'insertion" des chômeurs en formation. Il s'interroge sur les fondements normatifs d'un tel dispositif, mais aussi sur les conditions pratiques de sa réalisation. Il décrit les résultats obtenus et débouche sur la question fondamentale à poser dans le cadre de la participation des citoyens les plus fragiles : ouverture démocratique ou manipulation ? La réponse proposée se trouve évidemment entre ces deux pôles. [less ▲]

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See detailModulation of adipose tissue expression of murine matrix metalloproteinases and their tissue inhibitors with obesity
Maquoi, Erik ULg; Munaut, Carine ULg; Colige, Alain ULg et al

in Diabetes (2002), 51(4), 1093-1101

The potential role of the matrix metalloproteinase (MMP) system in the pathophysiology of the adipose tissue was investigated in a mouse model of nutritionally induced obesity. mRNA levels of 16 MMPs and ... [more ▼]

The potential role of the matrix metalloproteinase (MMP) system in the pathophysiology of the adipose tissue was investigated in a mouse model of nutritionally induced obesity. mRNA levels of 16 MMPs and 4 tissue inhibitors of MMPs (TIMPs) were measured by semiquantitative RT-PCR in adipose tissue isolated from mice maintained for 15 weeks on a standard or high-fat diet. In mice on standard diet, with the exception of MMP-8, all MMP and TIMP transcripts were detected in both gonadal and subcutaneous depots. In obese mice, the expression of MMP-3, -11, -12, -13, and -14 and TIMP-1 mRNAs was upregulated, whereas that of MMP-7, -9, -16, and -24 and TIMP-4 was downregulated. Most MMP and TIMP mRNAs were expressed at higher levels in stromal-vascular cells than in mature adipocytes. Analysis of adipose tissue by in situ fluorescent zymography revealed MMP-dependent proteolytic activities, demonstrating the presence of active MMPs in the intact tissue. In vitro conversion of adipogenic 3T3-F442A cells into mature adipocytes was associated with substantial modulations of MMP and TIMP expression. Moreover, this in vitro adipogenesis was reduced in the presence of a synthetic MMP inhibitor. Thus, the adipose tissue expresses a large array of MMPs and TIMPs, which modulate adipocyte differentiation. [less ▲]

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See detailEtude expérimentale des sons auto-entretenus d’un jet plan impactant sur une fente dans un milieu non confiné
Billon, Alexis ULg; Sakout, Anas; Valeau, Vincent

Conference (2002, April)

Cette étude expérimentale s’intéresse aux sons auto-entretenus générés par un écoulement non confiné : un jet turbulent à grand rapport d’aspect impactant sur une plaque munie d’une fente biseautée. Les ... [more ▼]

Cette étude expérimentale s’intéresse aux sons auto-entretenus générés par un écoulement non confiné : un jet turbulent à grand rapport d’aspect impactant sur une plaque munie d’une fente biseautée. Les éléments caractéristiques des sons auto-entretenus sont mis en avant. L’influence de la distance entre la plaque et la bouche du jet, ainsi que celle de la vitesse du jet ont été étudiées. La fréquence des sons mesurés est comparée aux fréquences propres longitudinales du système et à la fréquence la plus instable de la couche de cisaillement du jet, calculée à l’aide de la théorie de la stabilité linéaire. [less ▲]

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See detailMain concepts of the "European approach" to karst-groundwater-vulnerability assessment and mapping
Daly, Donald; Dassargues, Alain ULg; Drew, David et al

in Hydrogeology Journal (2002), 10(2), 340-345

In order to achieve some consistency in the establishment of groundwater intrinsic vulnerability maps in Europe. a new, approach is proposed by Working Group 1 of the European COST Action 620 on ... [more ▼]

In order to achieve some consistency in the establishment of groundwater intrinsic vulnerability maps in Europe. a new, approach is proposed by Working Group 1 of the European COST Action 620 on "Vulnerability mapping for the protection of carbonate (karst) aquifers". A general procedure is offered which provides consistency while allowing the required flexibility for application to a continent and under conditions of varying geology, scale, information availability, time, and resources. The proposed methodology is designed to be clearly more physically based than the existing vulnerability-mapping techniques. It takes the specificity of the karstic environments into account without necessarily excluding the applicability to other geological conditions. Combined "core factors" for overlying layers and for concentration of flow, account for the relative protection of groundwater from contamination while taking into account any bypass of the overlying layers. A precipitation factor is distinguished for describing: characteristics of the input of water to the system. Differentiation is made between groundwater resource intrinsic vulnerability Mapping and Source intrinsic vulnerability mapping. For the latter, a factor describing the karst network development is relevant. This short technical note describes a first stop in the work program of Working Group 1 of the COST Action 620. Future steps are now in progress to quantify the approach and to apply it in various European pilot areas. [less ▲]

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See detailAlgorithms for openings of binary and label images with rectangular structuring elements
Van Droogenbroeck, Marc ULg

in Talbot, Hugues; Beare, Richard (Eds.) International Symposium on Mathematical morphology (ISMM) (2002, April)

Two new families of algorithms for computing openings of binary and label images are presented in this paper. The first family of algorithms is based on an horizontal scan, and a vertical scan that takes ... [more ▼]

Two new families of algorithms for computing openings of binary and label images are presented in this paper. The first family of algorithms is based on an horizontal scan, and a vertical scan that takes the result of the horizontal scan as input. With the results of these two scans it is possible to compute an opening with respect to a rectangle of any size. The second family of algorithms is based on the construction of an exhaustive list of rectangles included in an object. Rectangles of this list all have a maximal extension, i.e. no larger rectangle included in a region contains them. The opening then results from filling the output image with rectangles larger than the structuring element. After a description of the algorithms we provide a comparison of several algorithms in terms of computation time efficiency. The comparison shows that some of the new algorithms advantageously compete with existing algorithms. [less ▲]

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See detailPurificacao, caracterizacao e dosagem radioimunologica de glicoproteinas associadas a gestacao em zebuinos
Melo de Sousa, Noelita ULg

Doctoral thesis (2002)

The pregnancy-associated glycoproteins (PAGs) constitute a large family of aspartic proteinases expressed in the outer epithelial cell layer of the Artyodactyla placenta. In the first part of the present ... [more ▼]

The pregnancy-associated glycoproteins (PAGs) constitute a large family of aspartic proteinases expressed in the outer epithelial cell layer of the Artyodactyla placenta. In the first part of the present work, two biochemical approaches were used to characterize PAGs isolated from zebu (Bos indicus) fetal cotyledons. The first procedure, used to isolate PAG from zebu placenta removed late in pregnancy, included extraction of proteins at neutral pH, acidic and ammonium sulfate precipitations, anion and cation exchange chromatographies. The second procedure, used to investigate PAG in placentas removed at early and mid gestational periods, included protein extractions at acid or alkaline pH followed by pepstatin-A agarose affinity chromatography. A bovine PAG radioimmunoassay was used to monitor the immunoreactivity throughout the isolation procedures. The most immunoreactive fractions issued from cation exchange and affinity chromatographies were analyzed by SDS-PAGE and Western Blot, before transfer to polyvinylidene difluoride (PVDF) membrane for NH2-microsequence determination. By use of SDS-PAGE and Western Blot, different isoforms of PAG with apparent molecular masses from 51 to 69 kDa and isoeletric points varying from 3.1 to 6.7 were identified in placentas from different gestational ages. After CM ceramic chromatography of all except 0.32 M NaCl DEAE fraction, the most immunoreactive proteins revealed N-terminal amino acid sequences (10 to 25 aa long) which were 100% identical to bovine PAG-1. The same sequence (14 aa long) was found after pepstatin-agarose affinity chromatography of proteins extracted from placentas removed earlier in pregnancy. These results converged towards the expression of one major N-terminal PAG amino acid sequence in zebu placentas at different gestational ages. In the second part of this study, two specific RIA systems were developed then used to measure plasmatic PAG concentrations during gestation and postpartum period in Azawak zebu cows. Twelve females palpated per rectum and diagnosed as pregnant were bled at 5-10 days interval approximately from Week 8 of gestation till Week 10 postpartum (pp). One zebu cow initially diagnosed as pregnant showed PAG concentrations lower than the assay sensitivity (<0.20 ng/ml) and did not calve. Another cow showed abnormally high PAG concentrations during gestation, being excluded from the general PAG profile. The 10 other zebu cows gave a very homogeneous PAG profile. In these animals, concentrations increased progressively from Week 8 to Week 35 of gestation (from 6.04.2 to 196.034.8 ng/ml), remaining relatively constant until Week 39 (210.874.8 ng/ml), when they increased sharply to reach their highest level (1,095.6607.2 ng/ml) at parturition. After delivery, PAG concentrations declined significantly (P<0.05) till the Week 2 postpartum (348.4  85.6 ng/ml) and slowly till the Week 10 postpartum. These results revealed that PAG concentrations in zebu cattle were lower than those previously described in taurine breeds between week 35 and 39 of gestation. [less ▲]

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See detailSIG réparti pour le partage des données spatiales de référence entre administrations publiques. Une étude de cas en Belgique
Donnay, Jean-Paul ULg

Scientific conference (2002, March 26)

Principes de la mise en place d''une infrastructure de données spatiales nationales, tenant compte des spécificités des différentes agences fédérales et régionales productrices de données de référence.

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See detailSynthesis, hydrolysis, biochemical and theoretical evaluation of 1,4-bis(alkoxycarbonyl)azetidin-2-ones as potential elastase inhibitors
Gérard, Stéphane; Dive, Georges ULg; Clamot, Brigitte et al

in Tetrahedron (2002), 58(12), 2423-2433

A series of 1,4-bis(alkoxycarbonyl)azetidin-2-ones, designed as potential suicide-inhibitors of serine proteases, has been synthesized and evaluated against porcine pancreatic elastase (PPE). The most ... [more ▼]

A series of 1,4-bis(alkoxycarbonyl)azetidin-2-ones, designed as potential suicide-inhibitors of serine proteases, has been synthesized and evaluated against porcine pancreatic elastase (PPE). The most active compound (K(i)similar to10 muM; reversible inhibitor) was equipped with phenethyloxycarbonyl and benzyloxycarbonyl side-chains at positions N1 and C4, respectively, with the (S)-configuration. H-1 NMR spectroscopic analysis of the reaction mixtures showed that the ester function is preferentially hydrolyzed, in both chemical and enzyme-catalyzed reactions, with regard to the azetidinone and urethane functions. Considering the three potentially sensitive carbonyl functions and the two stereoisomers, ab initio calculations were performed to determine the energetic barriers required to reach the transition state structures of hydrolysis in a model of the enzyme pocket. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailControl of proliferation, endoreduplication and differentiation by the Arabidopsis E2Fa-DPa transcription factor
De Veylder, L.; Beeckman, T.; Beemster, G. T. S. et al

in EMBO Journal (2002), 21(6), 1360-1368

New plant cells arise at the meristems, where they divide a few times before they leave the cell-cycle program and start to differentiate. Here we show that the E2Fa-DPa transcription factor of ... [more ▼]

New plant cells arise at the meristems, where they divide a few times before they leave the cell-cycle program and start to differentiate. Here we show that the E2Fa-DPa transcription factor of Arabidopsis thaliana is a key regulator determining the proliferative status of plant cells. Ectopic expression of E2Fa induced sustained cell proliferation in normally differentiated cotyledon and hypocotyl cells. The phenotype was enhanced strongly by the co-expression of E2Fa with its dimerization partner, DPa. In endoreduplicating cells, E2Fa-DPa also caused extra DNA replication that was correlated with transcriptional induction of S phase genes. Because E2Fa-DPa transgenic plants arrested early in development, we argue that controlled exit of the cell cycle is a prerequisite for normal plant development. [less ▲]

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See detailEvaluation de l'exactitude du capteur de glucose CGMS chez des patients hospitalisés
RADERMECKER, Régis ULg; Djakouré, C.; Réach, G. et al

Conference (2002, March 09)

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See detailThe tumorigenic diversity of the three PLAG family members is associated with different DNA binding capacities.
Hensen, Karen; Van Valckenborgh, Isabelle C C; Kas, Koen et al

in Cancer Research (2002), 62(5), 1510-7

Pleomorphic adenoma gene (PLAG) 1, the main translocation target in pleomorphic adenomas of the salivary glands, is a member of a new subfamily of zinc finger proteins comprising the tumor suppressor ... [more ▼]

Pleomorphic adenoma gene (PLAG) 1, the main translocation target in pleomorphic adenomas of the salivary glands, is a member of a new subfamily of zinc finger proteins comprising the tumor suppressor candidate PLAG-like1 (also called ZAC1 or lost on transformation 1) and PLAGL2. In this report, we show that NIH3T3 cells overexpressing PLAG1 or PLAGL2 display the typical markers of neoplastic transformation: (a) the cells lose cell-cell contact inhibition; (b) show anchorage-independent growth; and (c) are able to induce tumors in nude mice. In contrast, PLAGL1 has been shown to prevent the proliferation of tumor cells by inducing cell cycle arrest and apoptosis. This difference in function is also reflected in their DNA binding, as we show here that the three PLAG proteins, although highly homologous in their DNA-binding domain, bind different DNA sequences in a distinct fashion. Interestingly, the PLAG1- and PLAGL2-induced transformation is accompanied by a drastic up-regulation of insulin-like growth factor-II, which we prove is a target of PLAG1 and PLAGL2. This strongly suggests that the oncogenic capacity of PLAG1 and PLAGL2 is mediated at least partly by activating the insulin-like growth factor-II mitogenic pathway. [less ▲]

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See detailSpectroscopy of quasar host galaxies at the VLT: stellar populations and dynamics down to the central kiloparsec
Courbin, F.; Letawe, Géraldine ULg; Magain, Pierre ULg et al

in The Messenger (2002), 107

not available

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See detailMatrix metalloproteinase inhibition impairs adipose tissue development in mice
Lijnen, Roger; Maquoi, Erik ULg; Hansen, L. B. et al

in Arteriosclerosis, Thrombosis, and Vascular Biology (2002), 22(3), 374-379

The effect of galardin, a broad-spectrum matrix metalloproteinase (MMP) inhibitor, was studied in mice kept on a high fat diet (HFD). Five-week-old male wild-type mice were fed the HFD (42% fat) for up to ... [more ▼]

The effect of galardin, a broad-spectrum matrix metalloproteinase (MMP) inhibitor, was studied in mice kept on a high fat diet (HFD). Five-week-old male wild-type mice were fed the HFD (42% fat) for up to 12 weeks and were daily injected intraperitoneally with the inhibitor (100 mg/kg) or with vehicle. After 12 weeks of the HFD, the body weights of both groups were comparable, but the weight of the isolated subcutaneous (SC) or gonadal (GON) fat deposits was significantly lower in the inhibitor-treated group than in the control group (88 +/- 11 versus 251 +/- 66 mg, respectively, for SC fat [P<0.05]; 90 +/- 24 versus 217 +/- 30 mg, respectively, for GON fat [P<0.02]). The number of adipocytes was somewhat higher and the diameter was somewhat smaller (but not significantly) in adipose tissues of the inhibitor-treated group. Adipose tissue of the inhibitor-treated mice contained more collagen than did that of the vehicle-treated mice (Sirius red-stained area of 42 +/- 2.6% versus 22 +/- 4.4%, respectively, for SC fat [P<0.05]; 21 +/- 5.1% versus 4.7 +/- 0.92%, respectively, for GON fat [P<0.01]); a distinct collagen-rich cap was formed around the inhibitor-treated tissue. In situ zymography with casein- or gelatin-containing gels confirmed a reduced MMP activity in SC and GON adipose tissues of inhibitor-treated mice. Thus, in this model, growth and development of adipose tissue appears to be limited by the formation of a collagen-rich matrix cap around the inhibitor-treated tissue. These data suggest a functional role for MMPs in the development of adipose tissue. [less ▲]

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