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See detailA micro-model of the intra-laminar fracture in fiber-reinforced composites based on a discontinuous Galerkin/extrinsic cohesive law method
Wu, Ling ULg; Tjahjanto, Denny; Makradi, Ahmed et al

Conference (2013, June)

The hybrid discontinuous Galerkin (DG)/extrinsic cohesive law (ECL) method was recently proposed [1] to circumvent the drawbacks of the cohesive element methods. With the DG/ECL method, prior to fracture ... [more ▼]

The hybrid discontinuous Galerkin (DG)/extrinsic cohesive law (ECL) method was recently proposed [1] to circumvent the drawbacks of the cohesive element methods. With the DG/ECL method, prior to fracture, the flux and stabilization terms arising from the DG formulation at interelement boundaries are enforced via interface elements in a way that guarantees consistency and stability, contrarily to traditional extrinsic cohesive zone methods. At the onset of fracture, the traction–separation law (TSL) governing the fracture process becomes operative without the need to modify the mesh topology since the cohesive elements required to integrate the TSL are already present. This DG/ECL method has been shown to be an efficient numerical framework that can easily be implement in parallel with excellent scalability properties to model fragmentation, dynamic crack propagation in brittle and small-scale yielding materials, both for 3D problems and for thin structures [1, 2]. In this work, following the developments in [3], the DG/ECL method is extended to the study of composite materials failures at the micro-scale. The method is applied to study the transverse traction of composite materials in characteristic micro-volumes of different sizes. The method captures the debonding process, assimilated to a damaging process before the strain softening onset. It is shown that the density of dissipated energy resulting from the damage (debonding) remains the same for the different studied cell sizes. During the strain softening phase, a micro-crack initiates and propagates, in agreement with experimental observations. After strain softening onset, the extracted macroscale cohesive law, obtained by the method proposed in [4], is ultimately shown to converge for the different cell sizes. The predicted behaviors are then compared to experimental results obtained from laminate tests, and are found to be in good agreement. [less ▲]

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See detailMicro-modeling of retirement in Belgium
Dellis, A.; Desmet, R.; Jousten, Alain ULg et al

Report (2002)

The present paper studies the retirement incentives for elderly people in Belgium. We model the incentive structure built into the various public retirement and early retirement systems. First, we compute ... [more ▼]

The present paper studies the retirement incentives for elderly people in Belgium. We model the incentive structure built into the various public retirement and early retirement systems. First, we compute indicators of benefit entitlement such as the social security wealth. Then, we use three different incentive measures based on the notion of social security wealth. In a third step, we perform an empirical estimation of micro-econometric probit and option value models. From our exceptionally rich and broad database, we are able to compute rather accurate measures of all individuals’ pension wealth, as well as of the implicit tax rates the elderly workers face in case of delayed retirement. We find strong evidence of social security based financial incentives inducing most workers to retire at the earliest possible stage. Finally, we use the derived parameter estimates from the probit models to simulate the responses to various policy changes. [less ▲]

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See detailMicro-modelling of retirement incentives in Belgium
Jousten, Alain ULg; Dellis, A.; Desmet, R. et al

in Gruber, J.; Wise, D. (Eds.) Social Security Programs and Retirement around the World: Micro Estimation (2004)

Detailed reference viewed: 19 (8 ULg)
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See detailMicro-organismes pathogènes et viande : la traçabilité alliée de la sécurité.
Daube, Georges ULg

in Extrait du Bulletin de la Société Royale des Sciences de Liège (2001), 1

Detailed reference viewed: 22 (0 ULg)
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See detailMicro-phonochirurgie assistée au laser CO2 des lésions bénignes des cordes vocales
Remacle, Marc; Giovanni, Antoine; Lawson, George et al

in Cahiers d'Oto-rhino-laryngologie, de Chirurgie Cervico-faciale et d'Audiophonologie (Les) (2000), 35(6), 293-300

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See detailMicro-plasto-hydrodynamic lubrication: a fundamental mechanism in cold rolling
Laugier, Maxime; Boman, Romain ULg; Legrand, Nicolas et al

in Advanced Materials Research (2014), 966-967

Micro Plasto-Hydrodynamic (MPH) lubrication is a general mechanism in metal forming that consists in a re-lubrication of tool-piece solid contacts by an outflow of lubricant from pressurized “pockets” ... [more ▼]

Micro Plasto-Hydrodynamic (MPH) lubrication is a general mechanism in metal forming that consists in a re-lubrication of tool-piece solid contacts by an outflow of lubricant from pressurized “pockets” promoted by the plastic deformation. MPH lubrication is one of the main sources of friction variation (e.g. uncontrolled friction) in metal forming processes like strip drawing or cold rolling. This paper presents experimental results giving evidence of the MPH lubrication mechanism in cold rolling and a new lubrication model that predicts for strip drawing conditions MPH lubrication initiation and lubricant extension along the solid contacts initially in boundary condition. This MPH model could be implemented in a cold rolling model soon to help in high strength steels developments on cold rolling mills. [less ▲]

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See detailMicro-quantitative method for analysis of sterol levels in honeybees and their pollen loads
Vanderplanck, Maryse; Michez, Denis; Vancraenenbroeck, Sophie ULg et al

in Analytical Letters (2011), 44(10), 1807-1820

A Gas Chromatography-Flame Ionization Detector method for characterization and micro-quantification of sterols was developed. The applicability of this method was evaluated for determining sterolic ... [more ▼]

A Gas Chromatography-Flame Ionization Detector method for characterization and micro-quantification of sterols was developed. The applicability of this method was evaluated for determining sterolic compounds in pollen loads, larvae, and adults of the honeybee. After a multi-step procedure to extract and purify sterols, the compounds were identified on the basis of their retention data and quantified on the basis of peak areas from analyses. Quantifications were feasible with a limited amount of samples, allowing single specimen analyses and estimation of inter-individual variation. The reliability of this microquantitative method for sterol analysis was also investigated. [less ▲]

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See detailMicro-Raman spectroscopy and chemometrical analysis for the distinction of copper phthalocyanine polymorphs in paint layers
Defeyt, Catherine ULg; Van Pevenage, Jolien; Moens, Luc et al

in Spectrochimica Acta Part A : Molecular and Biomolecular Spectroscopy (2013), 115

In art analysis, copper phthalocyanine (CuPc) is often identified as an important pigment (PB15) in 20th century artworks. Raman spectroscopy is a very valuable technique for the detection of this pigment ... [more ▼]

In art analysis, copper phthalocyanine (CuPc) is often identified as an important pigment (PB15) in 20th century artworks. Raman spectroscopy is a very valuable technique for the detection of this pigment in paint systems. However, PB15 is used in different polymorphic forms and identification of the polymorph could retrieve information on the production process of the pigment at the moment. Raman spectroscopy, being a molecular spectroscopic method of analysis, is able to discriminate between poly- morphs of crystals. However, in the case of PB15, spectral interpretation is not straightforward, and Raman data treatment requires some improvements concerning the PB15 polymorphic discrimination in paints. Here, Raman spectroscopy is combined with chemometrical analysis in order to develop a procedure allowing us to identify the PB15 crystalline structure in painted layers and in artworks. The results obtained by Linear Discriminant Analysis (LDA), using intensity ratios as variables, demonstrate the ability of this procedure to predict the crystalline structure of a PB15 pigment in unknown paint samples. [less ▲]

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See detailMicro-scale flood risk analysis based on detailed 2D hydraulic modelling and high resolution geographic data
Ernst, Julien ULg; Dewals, Benjamin ULg; Detrembleur, Sylvain ULg et al

in Natural Hazards (2010), 55(2), 181-209

The paper presents a consistent micro-scale flood risk analysis procedure, relying on detailed 2D inundation modelling as well as on high resolution topographic and land use database. The flow model is ... [more ▼]

The paper presents a consistent micro-scale flood risk analysis procedure, relying on detailed 2D inundation modelling as well as on high resolution topographic and land use database. The flow model is based on the shallow-water equations, solved by means of a finite volume scheme on multiblock structured grids. Using highly accurate laser altimetry, the simulations are performed with a typical grid spacing of 2m, which is fine enough to represent the flow at the scale of individual buildings. Consequently, the outcomes of hydraulic modelling constitute suitable inputs for the subsequent exposure analysis, performed at a micro-scale using detailed land use maps and geographic database. Eventually, the procedure incorporates social flood impact analysis and evaluation of direct economic damage to residential buildings. Besides detailing the characteristics and performance of the hydraulic model, the paper describes the flow of data within the overall flood risk analysis procedure and demonstrates its applicability by means of a case study, for which two different flood protection measures were evaluated. [less ▲]

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See detailMicro-simulation of Social Security reforms in Belgium
Jousten, Alain ULg; Desmet, R.; Perelman, Sergio ULg et al

in Gruber, J.; Wise, D. (Eds.) Social Security Programs and Retirement around the World: Fiscal Implications of Reform (2007)

The present paper analyzes the budgetary impact of various Social Security reforms in the Belgian institutional setting. Our approach relies on parameters that were derived in Dellis et alii (2002) using ... [more ▼]

The present paper analyzes the budgetary impact of various Social Security reforms in the Belgian institutional setting. Our approach relies on parameters that were derived in Dellis et alii (2002) using a micro-modeling strategy. Focusing our attention on a hypothetical age cohort, we illustrate the budgetary impact that the reforms considered might have on the budget of the federal government. [less ▲]

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See detailMicro-technology for space mission
Loicq, Jerôme ULg

Conference (2007, October 03)

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See detailMicro-usinage par laser excimère
Gailly, Patrick ULg

Learning material (2007)

Detailed reference viewed: 10 (1 ULg)
See detailLes microalgues: un défi énergétique
Franck, Fabrice ULg

Conference (2013, June 06)

Les microalgues sont des micro-organismes photosynthétiques dont la culture commerciale en masse est pratiquée depuis les années '60. Les rendements en biomasse de la culture de microalgues sont ... [more ▼]

Les microalgues sont des micro-organismes photosynthétiques dont la culture commerciale en masse est pratiquée depuis les années '60. Les rendements en biomasse de la culture de microalgues sont supérieurs à ceux de cultures traditionnelles, et elle peut s'effectuer sur des terrains impropres à l'agriculture traditionnelle. Les perspectives d'utilisation de la biomasse microalgale pour la production de biocarburants ont suscité d'importants efforts de recherche au cours des années récentes. Les recherches en cours visent à améliorer les souches d'algues utilisables ainsi que différents aspects des procédés de production, de traitement et d'extraction de la biomasse algale afin d'aboutir à moyen terme à un procédé durable et économiquement viable. [less ▲]

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See detailMicroanalytical systems for separations of stratum corneum ceramides
Quinton, Loïc ULg; Gaudin, Karen; Baillet, Arlette et al

in Journal of Separation Science (2006), 29(3), 390-398

The small amount of lipids from human skin obtained with noninvasive sampling method led us to investigate microanalytical separation techniques. The lipid class analysis was performed with a micro ... [more ▼]

The small amount of lipids from human skin obtained with noninvasive sampling method led us to investigate microanalytical separation techniques. The lipid class analysis was performed with a micro polyvinyl alcohol-silica (PVA-Silm) column. The gradient elution was from heptane to acetone/butanol 90:10 v/v in 4%/min at 78 lL/ min. In addition an evaporative light scattering detector (ELSD) was modified for micro-LC. All solvents contained 0.1% of triethylamine and formic acid in stoichiometric amount, which increased the ELSD response. In these conditions, the cholesterol eluted before free fatty acid, and squalene and triglycerides close to the dead volume. The various ceramide classes eluted following the order of the increased number of hydroxyl groups. The LOD for ceramides was 2.2 ng. The advantages of this method are the use of a normal stationary phase more reliable due to its chemical stability, its surface homogeneity and its development in microchromatography without chlorinated solvents which offers small LOD and the whole profile of lipids present in stratum corneum (SC). A method using a narrow-bore PVA-Sil column was used to collect ceramide fraction. Then the molecular species were analysed with a porous graphitic carbon column in capillary LC using a gradient from CH3OH/CHCl3 70:30 v/v to CHCl3 at 2%/min with a flow rate at 5 lL/min. The LOD obtained for ceramide was 1 ng. Both methods were assessed with SC samples obtained by rinsing a 5.7 cm2 area of the forearm with 25 mL of ethanol. [less ▲]

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See detailMicroarray analyses of the effects of NF-kappaB or PI3K pathway inhibitors on the LPS-induced gene expression profile in RAW264.7 cells: synergistic effects of rapamycin on LPS-induced MMP9-overexpression.
Mendes, Sofia Dos Santos; Candi, Aurelie; Vansteenbrugge, Martine et al

in Cellular Signalling (2009), 21(7), 1109-22

Lipopolysaccharide (LPS) activates a broad range of signalling pathways including mainly NF-kappaB and the MAPK cascade, but recent evidence suggests that LPS stimulation also activates the PI3K pathway ... [more ▼]

Lipopolysaccharide (LPS) activates a broad range of signalling pathways including mainly NF-kappaB and the MAPK cascade, but recent evidence suggests that LPS stimulation also activates the PI3K pathway. To unravel the specific roles of both pathways in LPS signalling and gene expression profiling, we investigated the effects of different inhibitors of NF-kappaB (BAY 11-7082), PI3K (wortmannin and LY294002) but also of mTOR (rapamycin), a kinase acting downstream of PI3K/Akt, in LPS-stimulated RAW264.7 macrophages, analyzing their effects on the LPS-induced gene expression profile using a low density DNA microarray designed to monitor the expression of pro-inflammatory genes. After statistical and hierarchical cluster analyses, we determined five clusters of genes differentially affected by the four inhibitors used. In the fifth cluster corresponding to genes upregulated by LPS and mainly affected by BAY 11-7082, the gene encoding MMP9 displayed a particular expression profile, since rapamycin drastically enhanced the LPS-induced upregulation at both the mRNA and protein levels. Rapamycin also enhanced the LPS-induced NF-kappaB transactivation as determined by a reporter assay, phosphorylation of the p38 and Erk1/2 MAPKs, and counteracted PPAR activity. These results suggest that mTOR could negatively regulate the effects of LPS on the NF-kappaB and MAPK pathways. We also performed real-time RT-PCR assays on mmp9 expression using rosiglitazone (agonist of PPARgamma), PD98059 (inhibitor of Erk 1/2) and SB203580 (inhibitor of p38(MAPK)), that were able to counteract the rapamycin mediated overexpression of mmp9 in response to LPS. Our results suggest a new pathway involving mTOR for regulating specifically mmp9 in LPS-stimulated RAW264.7 cells. [less ▲]

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See detailMicroarray analysis of E2Fa-DPa-overexpressing plants uncovers a cross-talking genetic network between DNA replication and nitrogen assimilation
Vlieghe, Kobe; Vuylsteke, Marnik; Florquin, Kobe et al

in Journal of Cell Science (2003), 116(20), 4249-4259

dPreviously we have shown that overexpression of the heterodimeric E2Fa-DPa transcription factor in Arabidopsis thaliana results in ectopic cell division, increased endoreduplication, and an early arrest ... [more ▼]

dPreviously we have shown that overexpression of the heterodimeric E2Fa-DPa transcription factor in Arabidopsis thaliana results in ectopic cell division, increased endoreduplication, and an early arrest in development. To gain a better insight into the phenotypic behavior of E2Fa-DPa transgenic plants and to identify E2Fa-DPa target genes, a transcriptomic microarray analysis was performed. Out of 4,390 unique genes, a total of 188 had a twofold or more up- (84) or down-regulated (104) expression level in E2Fa-DPa transgenic plants compared to wild-type lines. Detailed promoter analysis allowed the identification of novel E2Fa-DPa target genes, mainly involved in DNA replication. Secondarily induced genes encoded proteins involved in cell wall biosynthesis, transcription and signal transduction or had an unknown function. A large number of metabolic genes were modified as well, among which, surprisingly, many genes were involved in nitrate assimilation. Our data suggest that the growth arrest observed upon E2Fa-DPa overexpression results at least partly from a nitrogen drain to the nucleotide synthesis pathway, causing decreased synthesis of other nitrogen compounds, such as amino acids and storage proteins. [less ▲]

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See detailMicroarray screening for target genes of the proto-oncogene PLAG1.
Voz, Marianne ULg; Mathys, Janick; Hensen, Karen et al

in Oncogene (2004), 23(1), 179-91

PLAG1 is a proto-oncogene whose ectopic expression can trigger the development of pleomorphic adenomas of the salivary glands and of lipoblastomas. As PLAG1 is a transcription factor, able to activate ... [more ▼]

PLAG1 is a proto-oncogene whose ectopic expression can trigger the development of pleomorphic adenomas of the salivary glands and of lipoblastomas. As PLAG1 is a transcription factor, able to activate transcription through the binding to the consensus sequence GRGGC(N)(6-8)GGG, its ectopic expression presumably results in the deregulation of target genes, leading to uncontrolled cell proliferation. The identification of PLAG1 target genes is therefore a crucial step in understanding the molecular mechanisms involved in PLAG1-induced tumorigenesis. To this end, we analysed the changes in gene expression caused by the conditional induction of PLAG1 expression in fetal kidney 293 cell lines. Using oligonucleotide microarray analyses of about 12 000 genes, we consistently identified 47 genes induced and 12 genes repressed by PLAG1. One of the largest classes identified as upregulated PLAG1 targets consists of growth factors such as the insulin-like growth factor II and the cytokine-like factor 1. The in silico search for PLAG1 consensus sequences in the promoter of the upregulated genes reveals that a large proportion of them harbor several copies of the PLAG1-binding motif, suggesting that they represent direct PLAG1 targets. Our approach was complemented by the comparison of the expression profiles of pleomorphic adenomas induced by PLAG1 versus normal salivary glands. Concordance between these two sets of experiments pinpointed 12 genes that were significantly and consistently upregulated in pleomorphic adenomas and in PLAG1-expressing cells, identifying them as putative PLAG1 targets in these tumors. [less ▲]

Detailed reference viewed: 17 (1 ULg)