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See detailDéfinition de propriétés acido-basiques dans les liquides ioniques de seconde génération
Robert, Thierry ULg

Doctoral thesis (2013)

The ionic liquids are salts having the particularity of being molten at temperatures lower than 100 °C. Consequently, these new solvents mainly made up of ions have original physicochemical properties ... [more ▼]

The ionic liquids are salts having the particularity of being molten at temperatures lower than 100 °C. Consequently, these new solvents mainly made up of ions have original physicochemical properties. Within a few years, the ionic liquids passed from a laboratory curiosity to a true field of research impossible to circumvent, currently in full rise. Indeed, the replacement of usual organic solvents in catalytic and/or separation processes by these neoteric solvents offers many advantages but also new opportunities for the “Green Chemistry”. However, the systematic exploitation of the ionic liquids as reactional media rests in particular on the understanding of their chemical properties, which for some of them are still scarcely known, such as the acidity for example. This thesis thus aims to undertake a study of the acido-basic properties of (and in) these solvents, and more particularly to determine the accessible levels of acidity for acid solutions (with added HOTf or HNTf2) in second generation ionic liquids such as [HNEt3][NTf2], [BMIm][NTf2], [BHIm][NTf2], [BMIm][BF4], [BMIm][OTf], [BMIm][PF6] and [BMIm][SbF6]. In order to evaluate these acidity levels, we propose two different methods, each one resting on an extra-thermodynamic assumption. The first, the Hammett acidity function H0, is based on the protonation equilibrium of indicators whose pKa's are proposed as solvent independent. The second, the Strehlow potentiometric function R0(H+), consists in measuring, in a given solvent, the electrochemical potential of the proton compared to the ferricinium/ferrocene redox couple whose potential is supposed to be independent of the solvent, and then to refer it versus the Normal Hydrogen Electrode (NHE) in water. The two methods lead to the same conclusions. Firstly, the ionic liquids are generally contaminated by residual basic impurities (from solvents needed for the synthesis…) which need to be neutralized before reaching the acidity characteristic of the medium. The levels of acidity then obtained are very high and can reach values as high as R00(H+) = -10 in the case of [BMIm][BF4]. Then, the accessible level of acidity in an ionic liquid depends mainly on the nature of its anion, and not of that of its cation. We thus obtain the following classification, by decreasing acidity: [PF6-] > [BF4-] > [NTf2-] > [OTf-], indicating that the triflate is the more solvating anion It was found however that the Hammett acidity function led, for the same concentration in acid, to different levels of acidity, depending on the indicator used. The ionic liquids would consequently be media less dissociating than estimated in the literature and the Hammett function would then be related to an apparent acidity (H0)app, underestimating the real acidity. Finally, a difference in acidity between HNTf2 and HOTf is observed in [BMIm][NTf2] and [BMIm][OTf], HNTf2 showing an acidic character stronger than HOTf. On the other hand, in [BMIm][OTf] these two acids show the same acidity since that of HNTf2 has been leveled by solvent. [less ▲]

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See detailLa définition du produit, premier pas dans la mise en place d'un plan marketing réussi pour la petite et moyenne entreprise débutante
Van Caillie, Didier ULg

in La Vie au Bureau (1991), 1991(Avril), 47-53

This paper describes and discusses why it's important to elaborate a precise and detailed definition of a product when trying to elaborate a winning marketing plan in an emerging SME

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See detailDéfinition du profil écologique de l'azobé (Lophira alata Banks ex Gaertn F., Ochnaceae) dans les forêts sempervirentes du Cameroun
Biwole, Achille ULg; Bourland, Nils ULg; Doucet, Jean-Louis ULg

Poster (2012, February 08)

Ekki or L. alata is a commercial timber species in Guinea-Congolian region considered vulnerable (IUCN, 2011). Indeed, its population structure shows a severe lack of regeneration in some rainforests ... [more ▼]

Ekki or L. alata is a commercial timber species in Guinea-Congolian region considered vulnerable (IUCN, 2011). Indeed, its population structure shows a severe lack of regeneration in some rainforests (Palla et al., 2002). Moreover, in logging areas, insufficient knowledge about its ecological profile limits any reliable modeling of population dynamics on a long term. Consequently, original research, to improve its ecological characterization to ensure its sustainable management is conducted in moist evergreen forest in southern Cameroon. First results on population dynamics of this species show, in plots study of recruitment, a population without major deficit regeneration. On its silvicultural ability, although that estimated on plantations on parks under 2 years old, the trends of growth (ca 30 and 0.5 cm / year respectively in height and diameter) and mortality (3, 3% / year) suggest a positive perspective. Current work in relation to other topics of research should provide further insights into its ecological profile in the evergreen forests of Cameroon. [less ▲]

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See detailDéfinition du profil écologique de l'azobé, Lophira alata, une espèce ligneuse africaine de grande importance : synthèse bibliographique et perspectives pour des recherches futures
Biwole, Achille ULg; Bourland, Nils ULg; Daïnou, Kasso ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(2), 217-228

Over two decades, labors made in order to promote sustainable management of African tropical forests are tackled to the lack of knowledge about this complex ecosystem. Ecological parameters of timber ... [more ▼]

Over two decades, labors made in order to promote sustainable management of African tropical forests are tackled to the lack of knowledge about this complex ecosystem. Ecological parameters of timber species are no more studied, this complicates long-term sustainable forest management. This literature review related to the ecology and silviculture of ekki, Lophira alata Banks ex C.F.Gaertn. (Ochnaceae), a main African timber species recorded as “vulnerable” in the IUCN Red List, will serve as a study’s case. The planned literature review reveals the doubt about its taxonomy, as well as the lack of understanding concerning its reproductive biology, growth conditions, population dynamics parameters, and the spatial distribution of its genetic diversity. The deficiency of knowledge about its ecological needs and the factors which have historically influenced its population dynamics explain why most silvicultural trails provide hazardous and uncertain results. Remedying these gaps in order to improve its ecological characterization and innovative silvicultural trails, would be a significant contribution to the sustainable management of its populations. [less ▲]

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See detailDéfinition du régulon DasR chez Streptomyces coelicolor, un réservoir pour la découverte de nouveaux gènes essentiels à l'induction de la différenciation morphologique et la production de métabolites secondaires
Colson, Séverine ULg

Doctoral thesis (2011)

Ce travail vise à comprendre les mécanismes d’induction du développement chez les Streptomyces. Chez ce genre bactérien, le facteur de transcription DasR a été identifié comme le premier régulateur global ... [more ▼]

Ce travail vise à comprendre les mécanismes d’induction du développement chez les Streptomyces. Chez ce genre bactérien, le facteur de transcription DasR a été identifié comme le premier régulateur global à la charnière entre le métabolisme primaire et le métabolisme secondaire, capable de percevoir l'état nutritionnel de l'environnement et d'adapter en conséquence la réponse des différents processus associés au développement (Rigali et al., 2006 et Rigali et al., 2008). La première ambition de cette thèse de doctorat a été d'évaluer l'ampleur du régulon DasR chez S. coelicolor afin d'obtenir une liste - exhaustive et appuyée par des critère de fiabilité - des gènes ciblés par ce régulateur global. L'hypothèse à la base de ce travail de prédiction était qu'au sein du régulon DasR se trouvaient peut-être des gènes de fonction encore inconnue mais essentiels au développement. Comprendre le rôle de ces protéines pouvait déboucher sur l'élucidation de nouvelles voies d'induction du développement et donc peut-être de nouvelles voies à exploiter pour induire le réveil des gènes cryptiques. La première démarche visant à répondre à ce premier objectif nous a amené à constater les lacunes des programmes web de prédiction des régulons existant, notamment le manque de flexibilité au niveau des critères de recherche et au niveau de l'exploitation des résultats obtenus, ainsi que l'absence de moyen permettant d'estimer la fiabilité de la prédiction. C'est pourquoi, dans un premier temps, nous nous sommes lancés le défi de créer un nouvel outil de prédiction des régulons procaryotiques qui répondrait davantage aux attentes des biologistes. Ce programme, nommé PREDetector (Prokaryotic Regulatory Elements Detector), a été réalisé en collaboration avec le Professeur Louis Wehenkel (Department of Electrical Engineering and Computer Science, Université de Liège) (Hiard et al., 2007). Les caractéristiques et les possibilités offertes par PREDetector sont expliquées et illustrées dans le premier chapitre des résultats. Le second chapitre des résultats - ainsi que l'annexe de cette thèse - sont quant à eux dédiés à l'exploitation de ce programme et la caractérisation de l'ensemble des cibles de DasR prédites chez S. coelicolor. Ensuite, et toujours motivé par un souci de présenter un travail fiable pour d'ultérieures investigations, une comparaison des régulons DasR prédits chez différents streptomycètes et autres actinomycètes (prédictions et démarches détaillées dans l'annexe de thèse), vient appuyer notre définition du noyau dur du régulon DasR - conservon DasR - déduit pour l'organisme modèle S. coelicolor. Enfin, nous passons à l'étape d'utilisation de ces données bioinformatiques avec l'étude de gènes/protéines dont l'expression est dépendante de DasR dans le but de peut-être établir de nouvelles connexions entre le métabolisme primaire et le développement chez la souche modèle S. coelicolor. De manière intéressante, le régulon DasR de S. coelicolor comprend plusieurs gènes codant pour des systèmes de transport ABC de sucre. A l'instar du PTSGlcNAc, ces transporteurs situés à l'interface cellule/environnement peuvent aussi être les senseurs de molécules cruciales pour l'induction du développement. Après le PTSGlcNAc, nous nous sommes donc concentrés sur l'étude du premier transporteur ABC de sucre régulé par DasR - en termes de fiabilité des prédictions et de conservation inter-espèces/-genres -, c'est-à-dire, le système DasABC. Dans le troisième chapitre des résultats nous démontrerons ainsi que DasA est une protéine impliquée dans le processus de différenciation morphologique de S. coelicolor (Colson et al., 2008). [less ▲]

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See detailDéfinition et applications de l'isocinétisme
Croisier, Jean-Louis ULg; Crielaard, Jean-Michel ULg

in Annales de Réadaptation et de Médecine Physique (1996, September), 39(6),

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See detailDéfinition et fonction d’un trésor d’église
George, Philippe ULg

in Bulletin du Centre d'Etudes Médiévales d'Auxerre (2005)

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See detailDéfinition et identification des processus de transformation pour l’analyse de la dynamique spatio-temporelle du paysage
Bogaert, Jan ULg; Ndihokubwayo, S; Bizimana, S et al

in Revue de l'Université du Burundi - Série Sciences Exactes (2008), 23

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See detailDéfinition et mesure de la criminalité liée aux drogues
Born, Michel ULg; De Ruyver, B.; Lemaître, André ULg et al

Book published by Academia Press (2008)

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See detailDefinition of moderate ischemic mitral regurgitation: it's time to speak the same language.
Fattouch, K.; Punjabi, P.; LANCELLOTTI, Patrizio ULg

in Perfusion (2013), 28(2), 173-5

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See detailDefinition of quality standards applicable to the purification and the expansion of mesenchymal stem cells for their use in haematopoietic, immunosuppressive and regenerative cellular therapy
Briquet, Alexandra ULg

Master of advanced studies dissertation (2005)

Mesenchymal stem cells (MSCs) reside within the stromal compartment of bone marrow and represent a plastic cell population for which pro-haematopoietic, immunosuppressive and regenerative properties are ... [more ▼]

Mesenchymal stem cells (MSCs) reside within the stromal compartment of bone marrow and represent a plastic cell population for which pro-haematopoietic, immunosuppressive and regenerative properties are poorly characterized. A characterization of MSC preparations was carried out with each passage in MSCGM or α-MEM + 20% FBS expansion media. We obtained 3 times more cells after 5 passages in MSCGM than in α-MEM + 20% FBS. We analysed the phenotype of MSCs after each passage by flow cytometry. At all passages and in both media cells were tested negative for CD45, strongly positive for CD73 and CD90 antigens and weakly positive for CD105 and CD106 antigens. We wanted to assess the MSC ability to differentiate into adipocytes, osteoblasts and chondroblasts. At all tested passages and in both media, MSCs differentiated in these three tissues when they were placed in the adequate induction medium. We used RayBio® Human Cytokine Antibody Array to analyse the presence of several cytokines in MSC-conditioned medium. At all passages and in both media, IL-6, IL-8 and VCAM-1 were more strongly expressed than the other cytokines. We used the CFU-F assay to evaluate the frequency and purity of MSCs in culture. We observed that CFU-F number reached a maximum at passages 3 and 4 after expansion in both MSCGM and in α-MEM + 20% FBS. We also observed a greater proportion of CFU-F for the cells expanded in MSCGM compared to the cells expanded in α-MEM + 20% FBS. To assess the haematopoietic supporting ability of MSCs, long term cultures were performed. We observed more colony-forming cells when long-term cultures were done with 1st and 2nd passages MSCs than when cultures were done with 3rd, 4th and 5th passages MSCs. In NOD/SCID mice we transplanted CD34+ uncultured cells or the expansion product of CD34+ cells co-cultured for one week with MSCs. Human chimerism was present in all conditions. We observed a greater human chimerism when CD34+ cells were co-cultured with MSCs from passage 4 than in the other conditions. In all conditions simultaneous expression of CD19 or CD33 antigens on human CD45+ cells demonstrated the presence of repopulating cells with lympho-myeloid potential. Despite the fact that MSCs had the same phenotype, differentiation potential and cytokine secretion profile at each passage and in both media, MSCs did have neither the same capacity to form CFU-F nor the same capacity to support haematopoiesis in vitro and in vivo. [less ▲]

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See detailDefinition of vocal pitch accuracy in a melodic context
Larrouy, Pauline ULg

Scientific conference (2014, March 28)

If we easily categorize sung performances as “in tune” or “out of tune”, it is not so evident to explicitly describe on which criteria our evaluation is based. This presentation reports recent work on ... [more ▼]

If we easily categorize sung performances as “in tune” or “out of tune”, it is not so evident to explicitly describe on which criteria our evaluation is based. This presentation reports recent work on pitch accuracy perception in a melodic context. The results allow to refine the notion of pitch accuracy and therefore to design objective tools for the evaluation of singer quality. [less ▲]

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