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See detailDifunctional anionic initiator based on 1.3-diisopropenylbenzene. 5. Effect of polar additives and initiator seeding on the synthesis of poly(styrene-b-butadiene-b-styrene) copolymer
Yu, Y. S.; Dubois, Philippe ULg; Teyssié, Philippe et al

in Macromolecules (1997), 30(24), 7356-7362

The initiation of butadiene and styrene polymerization by a pure hydrocarbon soluble difunctional organolithium, 1,3-bis(1-lithio-1,3,3‘-trimethylbutyl)benzene, has been studied in a hydrocarbon solvent ... [more ▼]

The initiation of butadiene and styrene polymerization by a pure hydrocarbon soluble difunctional organolithium, 1,3-bis(1-lithio-1,3,3‘-trimethylbutyl)benzene, has been studied in a hydrocarbon solvent. The initiation occurs in such a way that part of the diadduct remains unreacted. When a second monomer feed along with tetrahydrofuran (THF) is added to the living chains, the residual diadduct is activated to the point where novel chains are formed. Weakly polar additives such as lithium alkoxides and aromatic ether can prevent part of the initiator from being inactive, although these additives are not effective enough to initiate the controlled synthesis of poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymers. The seeding of the initiator which consists of butadiene oligomerization in the presence of anisole and tBuOLi in cyclohexane, has proved to be very efficient in providing SBS containing 85% 1,4-microstructure polybutadiene (PBD) and with high mechanical properties, e.g., ultimate tensile strength higher than 30 MPa and elongation at a break of 1000%. [less ▲]

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See detailDifunctional initiator based on 1,3-diisopropenylbenzene. 2. Kinetics and mechanism of the sec-butyllithium/1,3-diisopropenylbenzne reaction
Yu, Y. S.; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecules (1996), 29(5), 1753-1761

Kinetics of the addition of s-butyllithium (s-BuLi) to 1,3-diisopropenylbenzene (1,3-DIB) has been studied, and the activation energy has been found to be 17.5 kcal/mol. Addition of s-BuLi to 1,3-DIB in a ... [more ▼]

Kinetics of the addition of s-butyllithium (s-BuLi) to 1,3-diisopropenylbenzene (1,3-DIB) has been studied, and the activation energy has been found to be 17.5 kcal/mol. Addition of s-BuLi to 1,3-DIB in a 2/1 molar ratio results in an oligomer rather than the desired diadduct. This observation has to be compared to the anionic polymerization of 1,3-DIB (hydrocarbon solvent at 50 °C) which leads to a polymer bearing ca. one double bond per monomeric unit. Li-NMR analysis of the addition of s-BuLi to 1,3-DIB (2/1 molar ratio) confirms the nonequivalence of the lithium cations and shows that ca. 30% s-BuLi remains unreacted when 1,3-DIB has been completely consumed. In the early stage of the addition, the propagation rate is faster than depropagation and the average molecular weight increases. When a depropagation−propagation quasi-equilibrium is reached, the oligomer molecular weight remains constant. It finally decreases when no DIB is left, as a result of depropagation. When the s-BuLi/1,3-DIB adduct is used as an initiator for styrene polymerization in the presence of a polar solvent, such as THF, initiation by monofuntional, difunctional, trifunctional, and tetrafunctional species is observed. In an apolar solvent, however, polystyrene of a narrow molecular weight distribution and a functionality of 2 is formed. This experimental observation more likely indicates that depolymerization of the 1,3-DIB oligomers occurs upon the addition of styrene. A mechanism which accounts for this propagation−depropagation process has been proposed and experimentally supported. [less ▲]

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See detailDifunctional initiator based on 1,3-diisopropenylbenzene. 4. Synthesis and modification of poly(alkyl methacrylate-b-styrene-b-butadiene-b-styrene-b-alkyl methacrylate (MSBSM) thermoplastic elastomers
Yu, Y. S.; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1996), 34(11), 2221-2228

MSBSM five-block copolymers where B stands for butadiene, S for styrene, and M for either methyl methacrylate (MMA) or tert-butyl methacrylate (tBMA) have been synthesized by sequential anionic ... [more ▼]

MSBSM five-block copolymers where B stands for butadiene, S for styrene, and M for either methyl methacrylate (MMA) or tert-butyl methacrylate (tBMA) have been synthesized by sequential anionic polymerization in an apolar solvent by using a difunctional anionic initiator derived from 1,3-diisopropenylbenzene. These block copolymers show improved mechanical properties and an extended service temperature compared to traditional SBS thermoplastic elastomers. Upon hydrolysis and further neutralization of the PolytBMA end-blocks, the upper glass transition temperature (Tg) of the five-block copolymers has been raised up to about 150°C. A further increase in this service temperature (up to ca. 160°C) has resulted from the blending of sPMMA-SBS-sPMMA five-block copolymers with isotactic poly(methacrylate) (iPMMA), due to the formation of a stereocomplex. The tensile properties of these modified five-block copolymers have remained essentially unchanged. [less ▲]

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See detailDifunctional initiator based on 1,3-diisopropenylbenzene. 6. Synthesis of methyl methacrylate-butadiene-methyl methacrylate triblock copolymers
Yu, Y. S.; Dubois, Philippe ULg; Teyssié, Philippe et al

in Macromolecules (1997), 30(15), 4254-4261

Synthesis of PMMA−PBD−PMMA (MBM) triblock copolymers with a 1,3-diisopropenylbenzene- (DIB-) based initiator is studied. Diethyl ether, tert-butyl methyl ether, N,N,N‘,N‘-tetramethylethylenediamine (TMEDA ... [more ▼]

Synthesis of PMMA−PBD−PMMA (MBM) triblock copolymers with a 1,3-diisopropenylbenzene- (DIB-) based initiator is studied. Diethyl ether, tert-butyl methyl ether, N,N,N‘,N‘-tetramethylethylenediamine (TMEDA) and THF were found to be efficient polar additives for obtaining PMMA−PBD−PMMA triblock copolymers, but these triblock copolymers displayed a high 1,2-microstructure of the PBD block. A combination of the initiator seeding technique and weakly polar additives has allowed MBM triblock copolymers with high 1,4-microstructure of PBD to be obtained. These copolymers exhibited a definitely higher upper service temperature than conventional thermoplastic elastomers, i.e. SBS or SIS Kratons. The influence of chain microstructure, copolymer composition and block length on the mechanical properties has been studied. Short polystyrene blocks of ca. Mn 2000 have been incorporated in between the PBD central block and the PMMA outer sequences. A higher tensile strength was observed for these MBM-like triblock coplymers. Contamination by a diblock structure expectedly had a very depressive effect on the bulk properties, and the stress−strain behavior mainly depended on the PMMA content and secondarily on molecular weight. [less ▲]

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See detailDifunctional initiator based on 1,3-diisopropenylbenzene. 7. Mechanical and thermal properties of new butadiene-based thermoplastic elastomers
Yu, Yisong; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Rubber Chemistry and Technology (1997), 70(5), 820-838

Mechanical and thermal properties of SBS thermoplastic elastomers, in which S stands for polystyrene and B for polybutadiene, can be remarkably improved through end-capping by syndiotactic poly(methyl ... [more ▼]

Mechanical and thermal properties of SBS thermoplastic elastomers, in which S stands for polystyrene and B for polybutadiene, can be remarkably improved through end-capping by syndiotactic poly(methyl methacrylate) sequences. Furthermore, the upper service temperature of these sPMMA teleblock copolymers can also be enhanced by blending with isotactic PMMA so that the rubbery PBD soft segments are connected to high-melting stereocomplexed hard segments. The factors which affect the mechanical and thermal properties of these novel thermoplastic elastomers have been extensively investigated. [less ▲]

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See detailDifunctional initiators based on 1,3-diisopropenylbenzene. 3. Synthesis of a pure dilithium adduct and its use as difunctional anionic polymerization initiator
Yu, Y. S.; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Macromolecules (1996), 29(8), 2738-2745

The addition reaction of tert-butyllithium (t-BuLi) to 1,3-diisopropenylbenzene (1,3-DIB) has been studied. Under optimized conditions, i.e., reaction in cyclohexane at −20 °C and dropwise addition of 1,3 ... [more ▼]

The addition reaction of tert-butyllithium (t-BuLi) to 1,3-diisopropenylbenzene (1,3-DIB) has been studied. Under optimized conditions, i.e., reaction in cyclohexane at −20 °C and dropwise addition of 1,3-DIB to a 1:1 t-BuLi−triethylamine (Et3N) complex followed by a 1 h postreaction period, a pure diadduct is formed without concomitant oligomerization of 1,3-DIB. The behavior of this diadduct has been investigated, in apolar and polar solvents; triblock copolymers have been prepared and found to have interesting mechanical properties. [less ▲]

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See detailDifusion des inconnues hyperstatiques dans les voilures à longerons couplés
Fraeijs de veubeke, Baudouin ULg

in Bulletin du Service Technique de l'Aéronautique (1951), 24

This paper contains a first set of applications of the variational principles of elasticity to aeronautical structures.

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See detailDIGE application to investigate aphid adaptation to resistant host plant
Francis, Frédéric ULg; Goggin, Fiona; Guillonneau, François et al

in Abstract book (2006)

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See detailDigestibilité et fermentation intestinale de deux sources de protéines animales, soumises ou non à un traitement thermique, chez le rat en croissance
POELAERT, Christine ULg; Despret, Xavier; Thewis, André ULg et al

in Nutrition Clinique et Metabolisme (2014, December), 28(Supplement 1), 176-177

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See detailDigestibilite ileale des acides amines de regimes monocereale-tourteau de soja chez le porc.
Leterme, Pascal; Thewis, André ULg; Thielemans, Marie France et al

in Revue de l’Agriculture = Landbouwtijdschrift (1991), 44(3), 423-432

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See detailLa digestibilite ileale reelle des acides amines chez le porc methodes d'estimation et interet pratique.
Leterme, Pascal; Thewis, André ULg

in 27èmes Journées de la recherche porcine en France (1995, February)

The estimation of the true ileal digestibility of dietary amino acids in pigs requires the distinction between the flow of undigestive dietary amino acids reaching the end of the small intestine and the ... [more ▼]

The estimation of the true ileal digestibility of dietary amino acids in pigs requires the distinction between the flow of undigestive dietary amino acids reaching the end of the small intestine and the flow of endogenous amino aicds coming from the digestive secretions that are not reabsorbed. This article reviews the direct and indirect method available: N-free diet (classic or improved), the regression method, the homoarginin method, the isotope dilution technique using labelled animals or labelled dietary proteins and the in vitro methods. The cases where the knowledge of the true digestibility seems to be interesting are then studied (feedstuffs poor in proteins, rich in antinutritional factors, etc). Thereafter, different subjects are brought up for the discussion: the practical use of true digestibility values, the necessity of takinf the endogenous losses into account and the validity of the true digestibility as a predictor of the availability of an amino acid for the pig [less ▲]

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See detailDigestibility and fermentation of inulin in the weaned piglets digestive tract.
Rossi, Florence; Ewodo, C.; Fockedey, R. et al

in Proceedings of the International Symposium " Non-digestible oligosaccharides : healthy food for the colon?" (1997, December)

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See detailDigestibility and Metabolic Utilization and Nutritional Value of Leucaena leucocephala (Lam.) Leaves Meal Incorporated in the Diets of Indigenous Senegal Chickens
Ayssiwede, Simplice Bosco; Dieng, Abdoulaye; Chrysostome, Christophe et al

in International Journal of Poultry Sciences (2010), 9(8), 767-776

In the prospect of the Leuceana leucocephala leaves meal using as a protein ingredient source for indigenous Senegal chickens diets, a study was carried out to determine their nutrient utilization and ... [more ▼]

In the prospect of the Leuceana leucocephala leaves meal using as a protein ingredient source for indigenous Senegal chickens diets, a study was carried out to determine their nutrient utilization and nutritional value when incorporated at various levels in the diets. Twenty adult indigenous chickens with an average body weight of 1.22 kg were conducted in metabolic cages and allocated in four groups of five birds each. The groups were corresponded to four dietary treatments (LL0, LL7, LL14 and LL21) containing respectively 0, 7, 14 and 21% of Leuceana leaves meal. During the trial, birds were weighed at the beginning and at the end. Feed offered and refused, collected fresh excreta were weighed daily and the droppings were oven-dried at 60oC and ground per bird for six days. The ingredients and experimental diets used and collected excreta were subjected to chemical analyses. Results showed that the Leuceana leaves were relatively rich in protein (24.9% DM), ether extract (6.4% DM), crude fiber (14.2% DM) and Neutral detergent fiber (22.4% DM). It contained respectively 43.1% and 11.4% DM of nitrogen free extract and ash, particularly calcium (1.8%) and potassium (1.1% DM) and 2573.8 kcal/kg DM of metabolizable energy. The results of the trial showed that the inclusion of L. leucocephala leaves meal in the diet at 21% level, has no significant adverse effect on feed intake, average daily weight gain, feed conversion ratio and nutrients utilization (except ether extract) of adult indigenous Senegal chickens. It has significantly (p<0.05) improved the crude protein and metabolizable energy utilization in birds fed the 7% level inclusion diet (LL7). [less ▲]

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See detailDigestibility and nitrogen balance in steers offered forage supplemented with barley, sugar beet pulp and straw
Raskin, Pascale; Dufrasne, Isabelle ULg; Baldwin, Paule ULg et al

in Grassland Science in Europe (1998)

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See detailDigestibility of solvent-treated Jatropha curcas kernel by broiler chickens in Senegal
Nesseim, Thierry Daniel Tamsir; Dieng, Abdoulaye; Mergeai, Guy ULg et al

in Tropical Animal Health and Production (2015)

Jatropha curcas is a drought-resistant shrub belonging to the Euphorbiaceae family. The kernel contains approximately 60 % lipid in dry matter, and the meal obtained after oil extraction could be an ... [more ▼]

Jatropha curcas is a drought-resistant shrub belonging to the Euphorbiaceae family. The kernel contains approximately 60 % lipid in dry matter, and the meal obtained after oil extraction could be an exceptional source of protein for family poultry farming, in the absence of curcin and, especially, some diterpene derivatives phorbol esters that are partially lipophilic. The nutrient digestibility of J. curcas kernel meal (JKM), obtained after partial physicochemical deoiling was thus evaluated in broiler chickens. Twenty broiler chickens, 6 weeks old, were maintained in individual metabolic cages and divided into four groups of five animals, according to a 4 × 4 Latin square design where deoiled JKM was incorporated into grinded corn at 0, 4, 8, and 12 % levels (diets 0, 4, 8, and 12 J), allowing measurement of nutrient digestibility by the differential method. The dry matter (DM) and organic matter (OM) digestibility of diets was affected to a low extent by JKM (85 and 86 % in 0 J and 81 % in 12 J, respectively) in such a way that DM and OM digestibility of JKM was estimated to be close to 50 %. The ether extract (EE) digestibility of JKM remained high, at about 90 %, while crude protein (CP) and crude fiber (CF) digestibility were largely impacted by JKM, with values closed to 40 % at the highest levels of incorporation. J. curcas kernel presents various nutrient digestibilities but has adverse effects on CP and CF digestibility of the diet. The effects of an additional heat or biological treatment on JKM remain to be assessed. [less ▲]

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See detailDigestion de l'acide alginique chez les invertébrés
Franssen, J.; Jeuniaux, Charles ULg

in Cahiers de Biologie Marine (1965), 6

Alginolytic enzymes have been detected, by viscosimetric method and by analysis of hydrolytic products, in the digestive tract of Arenicola marina L. and of the Echinoderms Psammzchinus miliaris Gmelin ... [more ▼]

Alginolytic enzymes have been detected, by viscosimetric method and by analysis of hydrolytic products, in the digestive tract of Arenicola marina L. and of the Echinoderms Psammzchinus miliaris Gmelin and Hotothuria forkali della Chiaje, in the cristalline tube of Tapes decussatus L. (Lamellibranchia) and in all the 13 different species of Gastropoda so far studied. Alginase seems to be a permanent constituent of the enzymatic digestive equipement of Gastropoda, this enzyme indeed being secreted not only by phytophagous marine species, which feed on brown algae containing alginic acid, but also by carnivorous marine species and by phytophagous species terrestrial or living in fresh waters. However, a correlation appears to exist between the dietary habits and the amount of alginase in the digestive organs. In the cases so far studied, the optimum pH of alginases generally lies between 7,2 and 7,8. [less ▲]

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See detailDigestion de la chitine chez les Actinaires (Coelentérés anthozoaires)
Jeuniaux, Charles ULg

in Cahiers de Biologie Marine (1962), 3

Four species of Sea-anemones (Adamsia palliata Boh., Anemonia sulcata Penn., Anthopleura balli Cocks et Edwardsia callimorpha Gosse) have been studied. High amounts of chitinases and chitobiases have been ... [more ▼]

Four species of Sea-anemones (Adamsia palliata Boh., Anemonia sulcata Penn., Anthopleura balli Cocks et Edwardsia callimorpha Gosse) have been studied. High amounts of chitinases and chitobiases have been found in the gastroderm. The chitinolytic activities of the gastroderm are as high as those of the gastric mucosa of some insectivorous Vertebrates, in terms of wet weight of tissues. In the coetenteric fluid, little or no activity has been observed. Fragments of pure "native" chitin, prepared from leg tendons of Maia squinado, too big to be absorbed by phagocytosis, have been partially digested in the gastrocoel of Anemonia and Anthopleura. The digestion of the chitin proceeded irregularly along the free edges of the fragments, and many mesenteric filaments could be observed adhering closely to the chitin fragments. These observations suggest a process of "contact digestion", as described by early investigators, and recently confirmed by Nicol (1959) in the case of extracellular digestion of proteins. Extracellular digestion of chitin by Sea-anemones may be considered, in addition to extracellular digestion of proteins, as a biochemical adaptation in relation to predatory habits involving the capture of large sized preys, often covered with chitinous exosqueleton. [less ▲]

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See detailDigestion de la chitine chez les oiseaux et les mammifères
Jeuniaux, Charles ULg

in Annales de la Société Royale Zoologique de Belgique (1961), 92(1), 27-45

The distribution and localisation of chitinolytic enzymes (chitinase and chitobiase) have been studied in five different species of Birds and nine species of Mammals. Chitobiase has been found in aqueous ... [more ▼]

The distribution and localisation of chitinolytic enzymes (chitinase and chitobiase) have been studied in five different species of Birds and nine species of Mammals. Chitobiase has been found in aqueous extracts of many glandular tissues, but its activity is low everywhere. No chitobiase has been found in kidneys and muscles. The gizzard's contents and intestinal chyme of the Sparrow, of the Blackbird, of Liothrix lutea and of the Cock are able to hydrolyse "native" chitin. The chitinase is secreted by the mucosa of the glandular stomach. Chitinase secretion seems to be lacking in the Pigeon. Among Mammals, a secretion of gastric chitinase has been observed in a Bat (Rhinolophus ferrum-equinum), in two Insectivors, the Mole and of the Pig seems also to be able to synthesize this enzyme. The other Mammals so far studied (Rabbit, Cat, Sheep, Choloepus and Man) do not appear to secrete chitinase. These results suggest the existence of a relation between the dietary habits of Vertebrates and the secretion of chitinase by some of their glandular tissues. The gastric chitinase of the Hedgehog has an optimal pH in the range of 4.7 to 5.0, which does not differ from that of other well-known chitinases extracted from Streptomycetes, Snails or Insects. The difference between these enzymes and the gastric chitinase lies in the fact that the latter is much less inhibited in acid conditions than in neutral or alkaline ones. The gastric chitinase seems in fact to be active at the pH conditions of the gastric chymes. [less ▲]

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See detailLa digestion des albuminoïdes chez quelques invertébrés
Fredericq, Léon ULg

in Archives de zoologie expérimentale et générale (1879), VII

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