Macromolecular engineering of lactones and lactides. 24. Controlled synthesis of (R,S)-β-butyrolactone-b-ε-caprolactone block copolymers by anionic and coordination polymerization

in Macromolecules (1997), 30(19), 5591-5595

Block copolymers of (R,S)-β-butyrolactone and ε-caprolactone have been synthesized by combining the anionic polymerization of the first monomer with the coordinative ring-opening polymerization of the ... [more ▼]

Block copolymers of (R,S)-β-butyrolactone and ε-caprolactone have been synthesized by combining the anionic polymerization of the first monomer with the coordinative ring-opening polymerization of the second one. The copolymerization yield is close to 100% and the final molecular weight of each sequence can be predicted from the initial monomer-to-initiator molar ratio. The molecular weight distribution of copolymers obtained is quite narrow (Mw/Mn ≤ 1.3). According to NMR and DSC analysis, the polybutyrolactone block is atactic and totally amorphous, in contrast to the polycaprolactone block which is semicrystalline. A partial miscibility of the two blocks in the amorphous phase has however been detected. Thermal and enzymatic degradations of the block copolymers have been investigated. The enzymatic degradation rate promoted by the lipase form Rhizopus arrhizus strongly depends on the copolyester composition and increases with the β-butyrolactone content. [less ▲]

Le sédiment urinaire: pourquoi et comment?

Conference (1997, September 20)

Bovine Attaching and Effacing Escherichia Coli Possess a Pathogenesis Island Related to the Lee of the Human Enteropathogenic Escherichia Coli Strain E2348/69

in FEMS Microbiology Letters (1997), 154(2), 415-421

Attaching and effacing Escherichia coli (AEEC) has been described as a cause of diarrhea in calves. The molecular pathogenesis of AEEC was mainly studied in human enteropathogenic E. coli strain E2348/69 ... [more ▼]

Attaching and effacing Escherichia coli (AEEC) has been described as a cause of diarrhea in calves. The molecular pathogenesis of AEEC was mainly studied in human enteropathogenic E. coli strain E2348/69 in which the virulence correlated with the presence of a 35.4 kb pathogenesis island called LEE. We showed that several strains isolated from calves with diarrhea were able to produce attaching and effacing lesions in a rabbit ileal loop model and that they possess a pathogenesis island related to the LEE. Moreover, we showed that the LEE from bovine strains was inserted mainly at a different position in the chromosome compared to the human enteropathogenic E. coli strain E2348/69. [less ▲]

Side effects of repeated treatments with exogeneous gonadotropins in cattle, sheep and goats

(1997, September 13)

Presented in this paper are investigations on a possible side effect of repeated treatments with exogeneous gonadotropins in cattle, sheep and goats. First is given an historical approach of the discovery ... [more ▼]

Presented in this paper are investigations on a possible side effect of repeated treatments with exogeneous gonadotropins in cattle, sheep and goats. First is given an historical approach of the discovery of human and equine chorionic gonadotropins including their biochemical properties. This review is continued with a brief report of some basic notions concerning the immune system followed by the description of respective sensitivities of different species to repeated gonadotropic treatments. A summarized presentation of the results of our investigations and those of different authors on circulating antibodies against exogeneous gonadotropins in the same species is then proposed. A synthetic reflexion leads to point out the positive influence of the philogenetic distance between the species - source of the gonadotropins (human or equine)- and the treated species -human, bovine, caprine, ovine- on the intensity of the immune reaction. [less ▲]

Spinal injury and spinal cord injury

Conference (1997, September 12)

Escourgeon et Orge d'hiver

in Livre Blanc: Céréales - Gembloux - Informations avant les semis (1997, September 11)

Jl 13, a Potential Successor to Clozapine, Is Less Sensitive to Oxidative Phenomena

in Biochemical and Biophysical Research Communications (1997), 238(1), 252-5

The oxidation behaviour of JL 13, a promising antipsychotic, was investigated in comparison with clozapine and loxapine, by measuring their direct "radical scavenging" abilities and their efficacies in ... [more ▼]

The oxidation behaviour of JL 13, a promising antipsychotic, was investigated in comparison with clozapine and loxapine, by measuring their direct "radical scavenging" abilities and their efficacies in inhibiting the lipid peroxidation. In the lipid peroxidation system, the reactivity of these compounds with free radicals produced by gamma-irradiation of linoleic acid may be presented as follows: JL 13 = loxapine < clozapine. In two enzymatic systems (HRP/GSH and HRP/H2O2/ GSH) which generate the thiyl free radicals, clozapine produces a strong enhancement of the thiyl-radical EPR signal intensity while JL 13 and loxapine exhibit no or minimal effect on this signal. The redox potential values for the three derivatives confirm the spectro-photometric and EPR results. Following this study, we show that JL 13, although presenting a preclinical clozapine-like profile, appears less sensitive to oxidation than clozapine. [less ▲]

Pour des services intégrés de qualité en faveur de jeunes enfants : quels dispositifs de formation au niveau local ?

Conference (1997, September 05)

Noms propres d'étoiles.

in Ciel (Le) (1997), 59

Not Available

Description et commentaire de deux approches méthodologiques de la vidéo-évaluation des stages pratiques en didactique des langues germaniques à l'ULg (II)

in Education-Formation (1997), (247), 1-8

Dans cette deuxième partie (voir commentaire ci-dessous), nous décrivons une approche particulière de l'HETEROscopie de la pratique enseignante. Outre le formateur, cet atelier d'évaluation assistée par ... [more ▼]

Dans cette deuxième partie (voir commentaire ci-dessous), nous décrivons une approche particulière de l'HETEROscopie de la pratique enseignante. Outre le formateur, cet atelier d'évaluation assistée par la vidéo regroupe seize personnes : deux enseignants-stagiaires (E-S) qui ont accepté d'être filmés dans le cadre de leurs stages, leurs deux maîtres de stages, et douze E-S. Ces derniers sont amenés à observer, à analyser, à évaluer, sous différents angles, les leçons données par leurs deux collègues. Les deux E-S qui ont été filmés contextualisent le montage-vidéo (max. 20') de leur leçon et précisent les objectifs qu'ils poursuivaient. Les douze E-S sont répartis en quatre groupes de trois. Chaque groupe reçoit la grille d'évaluation utilisée dans le cadre des stages et choisit un foyer d'évaluation spécifique. A l'intérieur des quatre groupes, chaque étudiant a la responsabilité d'un sous-foyer d'évaluation particulier. Une synthèse de l'évaluation est ensuite proposée par un rapporteur de chaque groupe. Pour la deuxième leçon, les trois groupes changent de foyer d'évaluation. Des suggestions prioritaires sont finalement formulées par le formateur, les maîtres de stages et, éventuellement, les collègues E-E. L'article se clôture en examinant l'intégration de ces deux ateliers de vidéo-évaluation (voir commentaire ci-dessous) dans la macro-structure méthodologique de la formation initiale en didactique des langues germaniques à l'ULg. [less ▲]