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See detailLA STEAM EXPLOSION : PRINCIPE ET ACTION SUR LES MATERIAUX LIGNOCELLULOSIQUES
Jacquet, Nicolas ULg; Blecker, Christophe ULg; Paquot, Michel ULg

Poster (2009, December 16)

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites ... [more ▼]

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites par la formation d’acides organiques et du cisaillement résultant de la chute brutale de pression. Le procédé est composé de deux phases distinctes. D’une part, le vapocraquage qui consiste à faire pénétrer par diffusion, puis à condenser, la vapeur sous haute pression à l’intérieur de la structure du matériau. L’eau condensée à température élevée va initier l’hydrolyse des groupements acétyles contenus dans les xylanes et induire la formation d’acides organiques. Selon la sévérité des conditions (pression, température), les acides vont catalyser l’hydrolyse des fractions hémicellulosiques, induire des modifications dans la structure des lignines et modifier le degré de cristallinité de la fraction cellulosique. D’autre part, la décompression explosive. Cette phase est provoquée par une chute brutale de pression qui va entraîner la revaporisation d’une partie de l’eau condensée. L’expension brutale de la vapeur va induire des forces de cisaillement qui vont modifier les propriétés physiques (granulométrie, surface spécifique, rétention d’eau…) du matériau. [less ▲]

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See detailVariation linguistique et signification sociale chez les jeunes Bruxelloises issus de l’immigration maghrébine. Analyse socio-phonétique de trois variantes non standard.
Audrit, Stéphanie ULg

Doctoral thesis (2009)

The present PhD research concerns three non-standard phonetic variants, known as specific to the adolescents from Moroccan immigration, and the meso-social meanings linked to these variants. The meso ... [more ▼]

The present PhD research concerns three non-standard phonetic variants, known as specific to the adolescents from Moroccan immigration, and the meso-social meanings linked to these variants. The meso-social level is defined here as the profiles or social personae (Coupland 2001). My hypothesis is that macro-socially homogeneous speakers use non standard variants according to their belonging to contrasted meso-social profiles. This problem is tackled through the analysis of authentic data, collected during a one-year ethnographic survey inside of two Brussels schools. These schools had a mostly female and immigrated population. Among the two of them, a peer group constituting a community of practice (Eckert 2000, 2005) was chosen as the focus of the study. This ethnographic gathering of data has a double aim: (i) first, it has to allow to determine what the profiles specific to the investigated peer groups are; (ii) secondly, a long-term survey must allow to collect speech as close as possible of the speakers’ vernacular. The three non standard variants are the followings: (i) The reduced vowels: they are strongly reduced vowels that can completely disappear from the sound signal, in very atypical positions according to standard French. (ii) The back /A/: these realisations of /A/ are characterized by the backing of their articulation point, whose consequence is to move their timbre closer to this of /ɔ/ ; (iii) The marked variants of /r/: this large designation includes trill fricatives and fricatives produced with a large amount of noise. Analyzing the meso-social meaning of non standard variants requires a double methodology, both qualitative and quantitative. The qualitative part concerns the analysis of ethnographic data (interviews and fieldwork notes). It leads to the discovery of three contrasted speaker profiles, that is to say the messing-up girls, the provocatives and the modests. In the second part of the analysis, the existence of a link between the different speaker profiles and the use of each of the marked variants was investigated through statistical independence tests (chi square tests). These tests underline that the reduced vowels and the marked variants of /r/ are more used by the messing-up and the provocative girls, that is to say to speaker profiles which distance the traditional Moroccan and Muslim values. At the opposite, the back /A/ seem to have a double face, because they are linked with two very different profiles, the provocatives and the modests. This variant is also often mentioned as characteristic of the lower class language (Jamin 2005). It seems thus that the back /A/ have multiple meanings, whose point in common would be pejoration. If we come back to the initial hypothesis, the use of marked variants thus appears to be linked to the speakers’ belonging to contrasted profiles. However, these profiles are not the only factor to have an influence: the results of the tests show that, jointly to the profiles, the school has also an influence on the use of marked variants. This importance of school was furthermore underlined by several researches in sociology of education, where it is known as the school composition effect (Dumay & Dupriez 2005, 2008). [less ▲]

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See detailHydrolysis of starch by sorghum malt for maltodextrin production
Ba, Khady ULg; Destain, Jacqueline ULg; Thonart, Philippe ULg

Poster (2009, December 16)

Maltodextrin is a mixture of saccharides with a molecular weight between polysaccharides and oligosaccharides with DE lower than 20. Maltodextrin is more soluble in water than native starches, also is ... [more ▼]

Maltodextrin is a mixture of saccharides with a molecular weight between polysaccharides and oligosaccharides with DE lower than 20. Maltodextrin is more soluble in water than native starches, also is cheaper in comparison with other major edible hydrocolloids. Maltodextrin is obtained by moderate enzymatic or acidic hydrolysis of starch. The hydrolysis of starch, catalyzed by amylases, is the most important commercial enzyme process. The hydrolyzed products are widely applied in food, paper and textile industries. Because of the increasing demand for these enzymes in various industries, there is enormous interest in developing enzymes with better properties, such as raw starch-degrading amylases suitable for industrial applications and their cost-effective production techniques. Sorghum (Sorghum bicolor) is a widely grown crop in Africa. Obtaining enzymes from sorghum requires a transformation. The objective of this study was application of sorghum amylase for maltodextrin. Sorghum seeds were supplied by the ISRA (Bambey, Senegal). Seeds were germinated in the laboratory at 30°C for 72 h and the sorghum malt was dried at 40°C for 48 h. Corn starch (from Roquette, France) hydrolysis was assayed in a bioreactor of 2 l at a temperature of 65°C gently stirred. Raw starch was slurried in water (30% w/v) and sorghum malt was introduced, chloride calcium was added, pH was adjusted to 6. Maltodextrin was characterized in term of the dextrose equivalent (DE) during the hydrolysis. The yield of hydrolysis was evaluated by soluble solids (° BRIX) at different hydrolysis time. The glucose concentration released was measured by DNS method (Miller method). [less ▲]

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See detailUne très brève histoire des musiques populaires afro-américaines
Pirenne, Christophe ULg

Scientific conference (2009, December 15)

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See detailVariation in external morphology of resident bottlenose dolphins in Bahía San Antonio, Patagonia, Argentina
Vermeulen, Els ULg; Cammareri, Alejandro

in Journal of Marine Animals and Their Ecology (2009), 2(2), 3-6

A photo-identification study carried out in Bahía San Antonio (Patagonia Argentina) showed a variation in external morphology among year-round resident bottlenose dolphins. Out of 63 individually ... [more ▼]

A photo-identification study carried out in Bahía San Antonio (Patagonia Argentina) showed a variation in external morphology among year-round resident bottlenose dolphins. Out of 63 individually identified bottlenose dolphins, 15 were considered year-round residents of which three show variations in external morphology: they have a more falcate dorsal fin, darker coloration and shorter beak, physical characteristics described for the regional form of bottlenose dolphins present in the more southern province Chubut. The three morphologic distinct individuals, with one associated calf, could be re-identified in the study area up to 10 times over all the different seasons and up to now, no other bottlenose dolphins with similar characteristics could be observed in the area. On all occasions, they were re-identified in close occasions with each other and on 8 occasions in close association with other identified individuals. So far it was believed that the two regional forms of bottlenose dolphins present in Argentina were isolated. This communication is meant to document the residency and interaction of both regional forms in the same area. [less ▲]

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See detailThe diversity of clostridial hydrogenases revealed by genome sequencing projects
Calusinska, Magdalena ULg; Wilmotte, Annick ULg; Joris, Bernard ULg

Poster (2009, December 15)

Molecular hydrogen is a key intermediate in metabolomic interactions of a wide range of microorganisms. Hydrogen is also regarded as a key component in future energy systems as it is a sustainable, clean ... [more ▼]

Molecular hydrogen is a key intermediate in metabolomic interactions of a wide range of microorganisms. Hydrogen is also regarded as a key component in future energy systems as it is a sustainable, clean, and transportable energy carrier. Some microorganisms can produce hydrogen during a reversible reduction of protons to dihydrogen, a reaction which is catalyzed by the enzyme hydrogenases. On the basis of their bimetallocenter composition, hydrogenases are divided into three main groups, phylogenetically not related: [NiFe] hydrogenases, [Fe] only hydrogenases and FeS cluster free hydrogenases. The latter were described in methanogenic Archaea only. [NiFe] hydrogenases, composed of at least two subunits are well characterized and widely distributed between Archaea and Bacteria. However, only a few representatives of Clostridium sp. possess this type of enzyme. On the other hand, much less is known about the [Fe] only hydrogenases, that are usually monomeric enzymes and restricted to Bacteria and a few eukaryotic species. Genome sequencing projects gave a completely new insight into the diversity of forms of putative [Fe] only hydrogenases within the genus Clostridium. With the use of bioinformatic tools, we have described the unusual modularity of forms of these enzymes, from monomeric to tetrameric with a different number of accessory domains reacting with diverse redox partners. This fact seems to support the central role of hydrogenases in cell metabolism and quick adaptation of the host to changing environmental conditions. Moreover, the presence of multiple putative operons encoding for multisubunit [FeFe] hydrogenases is highlighting the fact that hydrogen metabolism is very complex in the Clostridium genus. [less ▲]

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See detailANNUAL SCIENTIFIC REPORT PHASE II "Impact of Phenology and Environmental Conditions on BVOC Emissions from Forest Ecosystems" "IMPECVOC"
Dewulf, Jo; Joó, Eva; Steppe, Kathy et al

Report (2009)

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See detailLes norovirus: nouveaux agents entéropathogènes.
HUYNEN, Pascale ULg; Mathijs, Elisabeth

Conference (2009, December 15)

Detailed reference viewed: 13 (0 ULg)
See detailLe Calvin's Case (1608), les deux corps du roi et la souveraineté divisée
Braillon, Charlotte ULg

Scientific conference (2009, December 15)

Detailed reference viewed: 26 (2 ULg)
See detailSuperhydrophobic surfaces by electrospinning of polymer mixtures
Grignard, Bruno ULg; Vaillant, Alexandre; De Coninck, Joel et al

Poster (2009, December 14)

Detailed reference viewed: 37 (6 ULg)
See detailAFM-based mechanical testing of electrospun PCL fibers
Croisier, Florence ULg; Duwez, Anne-Sophie ULg; Jérôme, Christine ULg et al

Poster (2009, December 14)

Poly(ε-caprolactone)(PCL forms a part of the aliphatic polyesters; the biodegradable and biocompatible character of these polymers makes them outstanding candidates for short-to medium-term biomedical ... [more ▼]

Poly(ε-caprolactone)(PCL forms a part of the aliphatic polyesters; the biodegradable and biocompatible character of these polymers makes them outstanding candidates for short-to medium-term biomedical applications, especially in the form of nanometric fibers,as their assembly mimics the extracellular matrix structure. However, a prerequisite to their application as nanofibrous biomaterial scaffolds is the investigation of their mechanical strength. In the present study, PCL fibers produced by electrospinning were individually tested using an AFM-based nano-scale three-point bending technique. [less ▲]

Detailed reference viewed: 97 (17 ULg)
See detailAdherent functional coatings from readily available acrylates
Cecius, Michaël ULg; Jérôme, Christine ULg

Poster (2009, December 14)

Detailed reference viewed: 21 (9 ULg)
See detailSynthesis of novel amphiphilic mikto-arm star-shaped copolymers
Riva, Raphaël ULg; Lazarri, Wenda; Billiet, Leen et al

Poster (2009, December 14)

Detailed reference viewed: 38 (7 ULg)
See detailCobalt-mediated radical polymerization (CMRP) and coupling reaction (CMRC): mechanistic advances ans synthetic opportunities
Debuigne, Antoine ULg; Poli, Rinaldo; De Winter, Julien et al

Poster (2009, December 14)

Detailed reference viewed: 34 (10 ULg)
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See detailPrediction of genetic interactions in yeast using machine learning
Schrynemackers, Marie ULg

Conference (2009, December 14)

Detailed reference viewed: 10 (3 ULg)
See detailThe Spatial Morphology of Equatorial Electron Beams Near Io
Jacobsen, S.; Saur, J. S.; Neubauer, F. M. et al

Conference (2009, December 14)

The Galileo spacecraft observed energetic field-aligned electron beams very close to Io during several flybys. We apply a three-dimensional magnetohydrodynamic (MHD) model of the far-field Io-Jupiter ... [more ▼]

The Galileo spacecraft observed energetic field-aligned electron beams very close to Io during several flybys. We apply a three-dimensional magnetohydrodynamic (MHD) model of the far-field Io-Jupiter interaction to simulate for the first time the location and spatial shape of field-aligned electron beams. Io continuously generates MHD waves by disturbing the Jovian magnetoplasma. Currents carried by Alfvén waves propagate predominantly along the magnetic field lines. As the number of charge carriers decreases along the travelpath, electrons are accelerated towards Jupiter. These energetic electrons precipitate into the Jovian ionosphere, visible as prominent Io footprint (IFP) emission. Electrons are also accelerated towards Io and form the equatorial beams observed by the Galileo spacecraft. Unlike the beam formation, the position and spatial structure of these beams has not been addressed in detail before. We use a 3D MHD model with initial conditions corresponding to the individual Galileo flyby and determine the spatial morphology of the beams in Io's orbital plane. Our results are in good agreement with the Galileo observations. We find that the ratio of the one-way traveltime of the Alfvén wave from Io to Jupiter and the convection time of the plasma past the obstacle controls the location of the beams. This leads to the conclusion that at other satellites with other plasma environments, e.g. Ganymede, Callisto, Europa and Enceladus, the electron beams might not be close to the satellite, but can be shifted significantly downstream along its plasma wake. Thus, the future search for field-aligned electron populations near a satellite should be further extended to the wake region. [less ▲]

Detailed reference viewed: 7 (2 ULg)