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See detailDetermination of the relationship between foam morphology and electrical conductivity of polymer/carbon nanotube nanocomposite foams
Tran, Minh Phuong ULg

Doctoral thesis (2014)

The lightweight of porous nanocomposites makes them attractive materials for various applications such as thermal and sound barriers, shock absorbers, insulation, packaging, and their porous structure is ... [more ▼]

The lightweight of porous nanocomposites makes them attractive materials for various applications such as thermal and sound barriers, shock absorbers, insulation, packaging, and their porous structure is very interesting in bone tissue engineering. Moreover, the incorporation of appropriate carbonaceous nanoparticles into polymeric foams contributes to the reinforcement of their mechanical performances but also renders them electrically conductive, consequently extending their potential interest in electromagnetic shielding (EMI) and electrostatic discharge (ESD) applications for instance. In this PhD thesis, we aim at designing various polymeric foams containing a conductive nanofiller (carbon nanotubes) and to identify the main morphological parameters (pore size, cell density, cell wall thickness,…) that affect and govern the final properties of the foams. In this work, the electrical conductivity of the foams is the main property investigated because it is governing their performances as materials for EMI absorbers, the main application targeted in this work. These important morphology/electrical conductivity relationships would indeed be very useful to guide the foam development towards the material with the best performances for the targeted applications. Two different foaming methods are used in this work: (i) the supercritical CO2 (scCO2) foaming technology and (ii) the freeze-drying process. The first technique enables to produce isotropic foams with spherical closed cells structures and the second one, oriented anisotropic foams with cylindrical open cells. The variation of the foaming parameters allows preparing foams with a large panel of morphologies required for the establishment of the structure/properties relationships. In parallel to this main objective, an improvement of the overall conductive performances of the nanocomposites foams is also investigated through the optimization of the foam morphology and the content in conductive nanofillers. [less ▲]

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See detailDynamics of the aurora at Jupiter
Bonfond, Bertrand ULg; Grodent, Denis ULg; Badman, Sarah et al

Conference (2014, February 19)

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See detailSpeciation slowing down in widespread and long-living tree taxa : insights from the tropical timber tree genus Milicia (Moraceae)
Daïnou, Kasso ULg; Mahy, Grégory ULg; Duminil, Jérôme et al

in Heredity (2014)

The long generation time and large effective size of widespread forest tree species can result in slow evolutionary rate and incomplete lineage sorting, complicating species delimitation. We addressed ... [more ▼]

The long generation time and large effective size of widespread forest tree species can result in slow evolutionary rate and incomplete lineage sorting, complicating species delimitation. We addressed this issue with the African timber tree genus Milicia that comprises two morphologically similar and often confounded species: M. excelsa, widespread from West to East Africa, and M. regia, endemic to West Africa. We combined information from nuclear microsatellites (nSSRs), nuclear and plastid DNA sequences, and morphological systematics to identify significant evolutionary units and infer their evolutionary and biogeographical history. We detected five geographically coherent genetic clusters using nSSRs and three levels of genetic differentiation. First, one West African cluster matched perfectly with the morphospecies M. regia that formed a monophyletic clade at both DNA sequences. Second, a West African M. excelsa cluster formed a monophyletic group at plastid DNA and was more related to M. regia than to Central African M. excelsa, but shared many haplotypes with the latter at nuclear DNA. Third, three Central African clusters appeared little differentiated and shared most of their haplotypes. Although gene tree paraphyly could suggest a single species in Milicia following the phylogenetic species concept, the existence of mutual haplotypic exclusivity and nonadmixed genetic clusters in the contact area of the two taxa indicate strong reproductive isolation and, thus, two species following the biological species concept. Molecular dating of the first divergence events showed that speciation in Milicia is ancient (Tertiary), indicating that long-living tree taxa exhibiting genetic speciation may remain similar morphologically. [less ▲]

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See detailLes herbivores, transformateurs de produits fourragers et de coproduits issus de l'agro-industrie en aliments nobles pour l'homme
Decruyenaere, Virginie; Lessire, Françoise ULg; Beckers, Yves ULg et al

in CRA-W (Ed.) La viande bovine remise en question: De sa production à sa consommation (2014, February 19)

Les prairies recouvrent près de 50% de la surface agricole utile en Wallonie. Dans certaines régions, la prépondérance des prairies dans le paysage wallon se justifie par des contraintes climatiques. Pour ... [more ▼]

Les prairies recouvrent près de 50% de la surface agricole utile en Wallonie. Dans certaines régions, la prépondérance des prairies dans le paysage wallon se justifie par des contraintes climatiques. Pour celles-ci bien souvent, les sommes de température et la durée de végétation active sont faibles et limitent considérablement le choix des cultures susceptibles d’atteindre la maturité avant récolte avec certitude. Dans d’autres régions, les prairies s’imposent davantage en raison de contraintes agronomiques : nature du sol, disposition des parcelles, relief du territoire, intérêt dans la rotation pour les prairies temporaires… Ainsi, la grande majorité des prairies de notre Région ne peut pas être remplacée par des cultures ; elles doivent dès lors être perçues comme une bonne alternative à la valorisation du territoire. Grâce à la présence du rumen en amont de l’estomac, les ruminants ont la capacité de transformer des productions non éligibles pour l’homme, tels que les fourrages et les co-produits des industries agro-alimentaires. Ces aliments, de nature essentiellement fibreuse mais pas pour autant pauvres en protéine et en énergie, sont largement fermentés par les micro-organismes du rumen qui les dégradent en composés plus simples, valorisables ensuite par l’animal. Par ce mécanisme, les ruminants contribuent à transformer ces aliments grossiers en produits nobles, tels que le lait et la viande. On comprend dès lors aisément que la présence des ruminants est étroitement liée aux superficies enherbées, elles-mêmes dépendantes des conditions pédo-climatiques d’une région. Malgré des systèmes de production intensifs et l’amélioration continue du potentiel génétique des animaux, les bovins restent peu dépendants des aliments du commerce comparativement aux autres spéculations animales. Ainsi, selon l’APFACA, de l’ordre de 16% des aliments composés produits en Belgique et importés sont utilisés pour les bovins, dont seulement 1/3 est écoulé dans la filière viande bovine. L’herbe, les produits herbagers et les aliments produits sur l’exploitation tels que le maïs restent donc majoritaires dans la ration des bovins élevés pour la production de viande. La valorisation de l’herbe et des produits herbagers dépend fortement des performances zootechniques recherchées. Les objectifs de croissance sont établis, en autre, sur base des prix offerts par la cheville variant avec les catégories d’âge et de poids d’abattage. Ces dernières années, il semble que les animaux abattus un peu plus tardivement soient moins dépréciés qu’auparavant, facilitant la formulation de rations à base de matières premières herbagères. A l’inverse, l’intensification dans le but de produire des animaux abattus plus jeunes ou à un poids supérieur, implique une croissance plus soutenue, et de ce fait la distribution de rations plus denses en énergie. Pour la formulation de telles rations, certains coproduits disposent de valeurs nutritionnelles intéressantes, permettant de satisfaire des besoins nutritionnels élevés, tout en conservant une certaine autonomie alimentaire. Leur valorisation au niveau local représente en outre un intérêt considérable pour la rentabilité des industries agro-alimentaires qui, sans la présence de l’animal, devraient trouver d’autres débouchés pour les coproduits sous peine d’être dans l’obligation de financer leur élimination. Cet exposé a pour objectif d’illustrer les potentiels, mais aussi les limites, des aliments produits localement pour les bovins viande, que ce soit selon leur type (vache de réforme- taurillon…), leur race et leurs performances zootechniques, mais aussi l’intérêt de ces aliments en termes d’efficiences alimentaire et économique. Il analyse les atouts et faiblesses de la spéculation viande bovine en ne se limitant pas à l’échelle de l’animal seul, mais en le replaçant en tant que véritable maillon de la chaîne agro-alimentaire. Ce positionnement permet non seulement de mieux cerner les enjeux de ces élevages au niveau de la production primaire, mais aussi leur importance dans les secteurs amont et aval. [less ▲]

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See detailModélisation de la dynamique des peuplements irréguliers
Ligot, Gauthier ULg

Scientific conference (2014, February 18)

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See detailL'écriture hiéroglyphique
Winand, Jean ULg

Scientific conference (2014, February 18)

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See detailTechnology Assessment and Science, Technology and Innovation Policy as Dancing Partners
Delvenne, Pierre ULg

Scientific conference (2014, February 18)

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See detailLiège et la France : de l’amitié à l’alliance
Balace, Francis ULg; Lanneau, Catherine ULg

Conference given outside the academic context (2014)

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See detailKosovo : la reconnaissance internationale après six années d'indépendance
Lika, Liridon ULg

Article for general public (2014)

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See detailDe l'écologie d'un discours heuristique d'acculturation à l'algèbre linéaire
DUNIA MWATI, Adrien

Doctoral thesis (2014)

ABSTRACT : Our research examines the sustainability of an acculturation heuristic discourse to Linear Algebra, prototypical gradual development of this discipline in a dialectical process with elementary ... [more ▼]

ABSTRACT : Our research examines the sustainability of an acculturation heuristic discourse to Linear Algebra, prototypical gradual development of this discipline in a dialectical process with elementary geometry. Our theoretical frameworks are borrowed from mathematics Didactic : mainly, Theory of Didactic Situations by Brousseau and Anthropological Theory of Didactics by Chevallard. These theories have enabled us to problematize the studied issue and make it a teaching "phenomenon" by giving intelligibility to the observations in a way that they are interpreted in a falsifiable hypothesis ( in Popper's sense ) which may integrate them all . In this context, the strict meaning given by Lakatos to heuristic speech has been broadly extended in terms of fundamental situation and praxeologies “modeling” according to Job and Schneider. A rational reading of historical and epistemological development of linear algebra then allowed us to build a "reference epistemological model" not only allowing us to answer to the question: "what is it to do linear algebra ?", but also to legitimize the referent heuristic discourse that served us as “phénoménotechnique”. Considering that our study is well marked, we have experimented in "secondary" and "university" institutions a heuristic device based on some selected aspects of the referent heuristic discourse. The analysis of observable that empirical work has identified has led us to identify several factors that combine to determine the ecological fragility of this speech and are at different levels of scale didactic codetermination (by Chevallard) : - The institutional variation of the curriculum of secondary education part in relation to linear systems. Including an emphasis on a resolution systems contract at the expense of their discussion, with a focus placed on the substitution method ; little technological discourse on the principles of equivalence systems and no intelligibility in terms of beams ; little work on equations as constraints with an impact on the lack of connection between the solution space of a system and the number of "independent" constraints, and finally, no ecological niche for the study of systems due to fragmentation of knowledge involved in multiple chapters. - The constraints inherent in the process of didactic transposition in terms of depersonalization and “désyncrétisation” of the knowledge but also in terms of progress in teaching time or chronogenesis. - Constraints related to teaching : a teacher accommodation to a socio-constructivist paradigm which appears as disguised exposition (ostension) and some ineffective activities ; a university pedagogy marked by “applicationnisme”, protectionism and a timing organization that puts theory on a pedestal where it is no longer in question. - An allegiance to the "mathematical" institution that is manifested, for instance, by some emblematic gestures linked to the mathematic rigor and which do not have great functionality. - Finally, an influence of the work of mathematicians on the didactic transposition, in the era of modern mathematics, which still inspires today didactic way, impeding (or being an obstacle for) linear algebra construction in dialectic with the geometry. The selected scenario for the role of interpretive hypothesis articulating these factors questions, in turn, all our education system which is too inspired by deductive theories in their completed text application. [less ▲]

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See detailAppui Institutionnel Université du Rwanda
Marini Djang'Eing'A, Roland ULg

Report (2014)

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See detailImproving halva quality with dietary fibres of sesame seed coats and date pulp, enriched with emulsifier
Elleuch, Mohamed; Bedigian, Dorothea; Maazoun, Bouthaina et al

in Food Chemistry (2014), 145

Supplementation of halva with waste products of manufacturing, for example defatted sesame seed coats (testae) and date fibre concentrate, can improve its nutritional and organoleptic qualities. These ... [more ▼]

Supplementation of halva with waste products of manufacturing, for example defatted sesame seed coats (testae) and date fibre concentrate, can improve its nutritional and organoleptic qualities. These constituents provide high fibre content and technological potential for retaining water and fat. Standard halva supplemented with date fibre concentrate, defatted sesame testae and emulsifier was evaluated for oil separation, texture and colour changes, sensory qualities and acceptability to a aste panel. Addition of both fibres with an emulsifier, improved emulsion stability and increased the hardness of halva significantly. The functional properties of sesame testae and date fibres promote nutrition and health, supplying polyphenol antioxidants and laxative benefits. [less ▲]

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See detailSemiparametric Bayesian frailty model for clustered interval-censored data
Cetinyürek, Aysun ULg; Lambert, Philippe ULg

Report (2014)

The shared frailty model is one of the popular tool to analyze correlated right-censored time-to-event data. In the shared frailty model, the latent frailty is assumed to be shared by the members of a ... [more ▼]

The shared frailty model is one of the popular tool to analyze correlated right-censored time-to-event data. In the shared frailty model, the latent frailty is assumed to be shared by the members of a cluster and is assigned a parametric distribution, typically, a gamma distribution due to its conjugacy. However, in case of interval-censored time-to-event data, the inclusion of gamma frailties results in complicated intractable likelihoods, where the conjugacy property does not hold anymore. Here, we propose a semiparametric Bayesian frailty model for analyzing such data. We discuss three parametric specifications for frailty distribution in the analysis of interval-censored data. Afterwards we call particular attention to nonparametric specification of the frailty distribution. The results of the simulation study suggest that the proposed approach is robust to misspecification of the frailty distribution. Moreover, the performance of the proposed methodology is quite good in practical situations where the frailty distribution is multimodal or skewed. The approach is applied to dental data arising from the Signal Tandmobiel Study. [less ▲]

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See detailAdaptation ou trahison ? Réflexion sur le cinéma d'A. Kechiche
Hagelstein, Maud ULg

Conference given outside the academic context (2014)

Lors du déjeuner littéraire, nous discuterons de l'adaptation au cinéma de la bande dessinée de Julie Maroh, "Le bleu est une couleur chaude", publiée par Glénat en mars 2010. On pourra partir de ce qui ... [more ▼]

Lors du déjeuner littéraire, nous discuterons de l'adaptation au cinéma de la bande dessinée de Julie Maroh, "Le bleu est une couleur chaude", publiée par Glénat en mars 2010. On pourra partir de ce qui fait le propre des médias concernés - la bande dessinée et le cinéma - pour aborder leur rapport respectif à la temporalité et au récit. Dans ce cas précis, l'exercice d'adaptation est avant tout un effort de transcription entre des domaines d'expression aux moyens très différents. On abordera en priorité le rapport fiction/réalité, en décrivant les nombreux effets de décalage et de détournement : une histoire véritablement vécue est transformée en semi-fiction par le dessin, reprise ensuite par le réalisateur A. Kechiche. Celui-ci rend à l'histoire fictive un nouveau degré de réalité en provoquant une expérience cinématographique à la fois jouée et vécue par les actrices de son film. Entre le récit et la réalité, on a donc un système de renvois incessants, que l'on essaiera de décrypter pour montrer comment ce récit de passion gagne en intensité. [less ▲]

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See detailWood charcoal analysis: a relatively new tool for palaeoecology in tropical Africa
Morin-Rivat, Julie ULg; Biwole, Achille ULg; Bourland, Nils ULg et al

Scientific conference (2014, February 14)

This is an introduction about wood charcoal properties, collection and taxonomical identification in the framework of palaeoecological studies in Central Africa through examples of possible applications.

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