Interactions between a buffered amine oxide impregnation carrier and an acrylic resin, and their relationship with moisture

Wood used outdoor is subjected to different sources of degradation and should be protected properly. In this study, acrylic resins were added to a wood impregnation system using amine oxides and propiconazole, an organic fungicide, to create a two-part wood protection preservation treatment. Since amine oxides can diffuse readily into wood, this treatment protected both the surface and inner structure of the treated wood following a simple dipping. Many aspects of the treatment were studied: the adhesion of the acrylic coatings, their permeability to water, and the impregnation depth of the propiconazole. In each case, a particular attention was accorded to the interactions between the resins and the impregnation system. Adhesion and permeability tests were coupled with an artificial aging process simulating severely wet conditions. Amine oxides reduced the adhesion of the coatings but did not impair their aging properties. Because of their hydrophilic nature, they also increased the permeability to liquid water, although they did not affect the air moisture permeability. The penetration of the propiconazole, estimated with a dye, decreased with the resin. Overall, the two parts of the treatment lightly impaired each other, but the practical aspect of this treatment may overcome these disadvantages

Conception d'un outil didactique pour l'implantation du multimédia en arts plastiques auprès d'élèves de 12 à 16 ans

Mon expérience dans l'enseignement et la formation des maîtres au Québec et aux États-Unis, ainsi que la recherche relative à cette thèse ont permis de découvrir les points de force et les lacunes de l'enseignement des nouvelles technologies dans le domaine des arts, plus particulièrement auprès d'élèves de 12 à 16 ans du secondaire, objet d'étude de la présente thèse. La compilation de la documentation, les observations dégagées sur le terrain et les expérimentations viennent renchérir ces propos. Les chercheurs, pédagogues et autres intervenants du milieu signalent, entre autres, le désarroi ressenti par les enseignant(e)s au secondaire devant l'ampleur de l'apprentissage à faire des technologies de l'information et de la communication (TICs) et expliquent le phénomène, chacun à sa façon et à partir de son contexte. Les entrevues, réalisées auprès d'experts en la matière, s'ajoutent aux propos des spécialistes. La présente recherche pose la question de l'intégration des TICs en parallèle à la réflexion menée dans la thèse. Celle-ci tente d'identifier les besoins des enseignants intégrant les nouvelles technologies dans le domaine des arts. Plusieurs techniques et exercices se sont développés, formant une méthode pour répondre aux besoins identifiés. Cette méthode, qui s'articule à travers différents outils, se présente en cinq modules visant chacun l'un des domaines de l'intégration du multimédia. Cette approche cherche à renforcer les apprentissages, ainsi que les stratégies pédagogiques et à introduire une façon de faire novatrice, intégrant la science, l'art et la technologie, s'inspirant des attentes du nouveau programme de l'école québécoise. Elle prend la forme du Cahier d'activités. Les nombreuses activités stratégiques proposées peuvent aller jusqu'à modifier ou même influencer les orientations de la démarche de création. De plus, un apport visuel permet à l'enseignant de visualiser ces activités, ce qui contribue à les faciliter et les démystifier. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Enseignement des arts médiatiques, Technologies de l'information et de la communication (TICs), Cahier d'activités, Modèles pédagogiques, Transfert entre arts plastiques et arts médiatiques, Niveau secondaire, Besoins des enseignants

Food Limitation in Larval Fish: Ontogenetic Variation in Feeding Scope and Its Potential Effect on Survival

We used the radiated shanny Ulvaria subbifurcataas a model species to explore the relative gut fullness from hatch to metamorphosis of wild larvae, and compared these values with those of laboratory-reared larvae fed at maximum rates. Ingestion rates of most wild larvae were above starvation levels but below the maximum feeding levels of laboratory-reared larvae. Twenty-six percent of freshly-hatched wild larvae and 11% of large, pre-settlement wild larvae had insufficient food in their stomach to satisfy metabolic requirements. These results, taken on their own, are consistent with the much hypothesized increased foraging performance and survival of larger larvae relative to smaller conspecifics. However, feeding scope-defined as the difference between the minimum daily food required for maintenance and the maximum set by gut capacity-increased disproportionately with size during ontogeny. As a result, none of the larger (\u3e 500 µg C) wild larvae fed at saturating levels. We conclude that environmental factors operating to increase encounters between larvae and prey (e.g. prey densities, turbulence, patch encounter) and ingestion rates will affect smaller and larger larvae differently. As a consequence, increased encounter rates should lead to increased survival in smaller larvae, and (primarily) to increased growth in larger larvae

Evaluation of In Vitro Uterotonic Activities of Fruit Extracts of Ficus asperifolia in Rats

The aim of the present study was to determine the uterotonic activities of Ficus asperifolia and investigate its mechanism. The effects of aqueous and methanol extracts of the dried fruits of F. asperifolia (0.05–1.60 mg mL−1) were evaluated on estrogenized isolated rat uterus in the presence and absence of atropine (1.73–55.27 nM), pyrilamine maleate (1.25 × 10−3 to 40 × 10−3 M), indomethacin (0.06 × 10−5 to 2.00 × 10−5 M) or hexamethonium (0.66 × 10−4 to 21.43 × 10−4 M). Aqueous (EC50, 0.36 mg mL−1) and methanol (EC50, 0.22 mg mL−1) extracts as well as oxytocin (EC50, 0.02 nM), acetylcholine (EC50, 7.87 nM) and histamine (EC50, 0.76 nM) evoked concentration-dependent contractions of the uterus. Atropine, pyrilamine maleate and indomethacin concentration dependently blocked the response of the uterus to acetylcholine (IC50, 4.82 nM), histamine (IC50, 2.49 nM) and oxytocin (IC50, 0.07 nM), respectively, and to aqueous extract. Hexamethonium produced graded decreases in oxytocin-induced uterine contractions (IC50, 0.37 μM), but did not prevent the contractile effects of the aqueous extract (IC50, 9.88 μM). These results suggest that F. asperifolia-induced uterotonic effect is related to the release of prostaglandins and contraction of the myometrial cells through muscarinic, oxytocic and H1 histamine receptors. These data further give added value to the ethnic use of F. asperifolia for its abortificient and contraceptive properties

Antibody persistence and booster responses to split-virion H5N1 avian influenza vaccine in young and elderly adults

Avian influenza continues to circulate and remains a global health threat not least because of the associated high mortality. In this study antibody persistence, booster vaccine response and cross-clade immune response between two influenza A(H5N1) vaccines were compared. Participants aged over 18-years who had previously been immunized with a clade 1, A/Vietnam vaccine were re-immunized at 6-months with 7.5 mu g of the homologous strain or at 22-months with a clade 2, alum-adjuvanted, A/Indonesia vaccine. Blood sampled at 6, 15 and 22-months after the primary course was used to assess antibody persistence. Antibody concentrations 6-months after primary immunisation with either A/Vietnam vaccine 30 mu g alum-adjuvanted vaccine or 7.5 mu g dose vaccine were lower than 21days after the primary course and waned further with time. Re-immunization with the clade 2, 30 mu g alum-adjuvanted vaccine confirmed cross-clade reactogenicity. Antibody crossreactivity between A(H5N1) clades suggests that in principle a prime-boost vaccination strategy may provide both early protection at the start of a pandemic and improved antibody responses to specific vaccination once available

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Titre de l'écran-titre (visionné le 14 nov. 2007)Également disponible en format papie

Bottom-Up Regulation of Capelin, a Keystone Forage Species

The Northwest Atlantic marine ecosystem off Newfoundland and Labrador, Canada, has been commercially exploited for centuries. Although periodic declines in various important commercial fish stocks have been observed in this ecosystem, the most drastic changes took place in the early 1990s when the ecosystem structure changed abruptly and has not returned to its previous configuration. In the Northwest Atlantic, food web dynamics are determined largely by capelin (Mallotus villosus), the focal forage species which links primary and secondary producers with the higher trophic levels. Notwithstanding the importance of capelin, the factors that influence its population dynamics have remained elusive. We found that a regime shift and ocean climate, acting via food availability, have discernible impacts on the regulation of this population. Capelin biomass and timing of spawning were well explained by a regime shift and seasonal sea ice dynamics, a key determinant of the pelagic spring bloom. Our findings are important for the development of ecosystem approaches to fisheries management and raise questions on the potential impacts of climate change on the structure and productivity of this marine ecosystem

Requirement of Caprine Arthritis Encephalitis VirusvifGene forin VivoReplication

AbstractReplication ofvif-caprine arthritis encephalitis virus (CAEV) is highly attenuated in primary goat synovial membrane cells and blood-derived macrophages compared to the wild-type (wt) virus. We investigated the requirement for CAEV Vif forin vivoreplication and pathogenicity in goats by intra-articular injection of either infectious proviral DNA or viral supernatants. Wild-type CAEV DNA or virus inoculation induced persistent infection resulting in severe inflammatory arthritic lesions in the joints. We were unable to detect any sign of virus replication invif-CAEV DNA inoculated goats, whilevif-CAEV virus inoculation resulted in the seroconversion of the goats. However, virus isolation and RT-PCR analyses on blood-derived macrophage cultures remained negative throughout the experiment as well as in joint or lymphoid tissues taken at necropsy. No pathologic lesions could be observed in joint tissue sections examined at necropsy. Goats inoculated with thevif-virus demonstrated no protection against a pathogenic virus challenge. These results demonstrate that CAEV Vif is absolutely required for efficientin vivovirus replication and pathogenicity and provide additional evidence that live attenuated lentiviruses have to establish a persistent infection to induce efficient protective immunity

Organic Nitrogen Uptake and Assimilation in Cucumis sativus Using Position-Specific Labeling and Compound-Specific Isotope Analysis

Organic nitrogen is now considered a significant source of N for plants. Although organic management practices increase soil organic C and N content, the importance of organic N as a source of crop N under organic farming management systems is still poorly understood. While dual-labeled (13C and 15N) molecule methods have been developed to study amino acid uptake by plants, multiple biases may arise from pre-uptake mineralization by microorganisms or post-uptake metabolism by the plant. We propose the combination of different isotopic analysis methods with molecule isotopologues as a novel approach to improve the accuracy of measured amino acid uptake rates in the total N budget of cucumber seedlings and provide a better characterization of post-uptake metabolism. Cucumber seedlings were exposed to solutions containing L-Ala-1-13C,15N or U-L-Ala-13C3,15N, in combination with ammonium nitrate, at total N concentrations ranging from 0 to 15 mM N and at inorganic/organic N ratios from 10:1 to 500:1. Roots and shoots were then subjected to bulk stable isotope analysis (BSIA) by Isotope Ratio Mass Spectrometry (IRMS), and to compound-specific stable isotope analysis (CSIA) of the free amino acids by Gas Chromatography – Combustion – Isotope Ratio Mass Spectrometry (GC-C-IRMS). Plants exposed to a lower inorganic:organic N ratio acquired up to 6.84% of their N from alanine, compared with 0.94% at higher ratio. No 13C from L-Ala-1-13C,15N was found in shoot tissues suggesting that post-uptake metabolism of Ala leads to the loss of the carboxyl-C as CO2. CSIA of the free amino acids in roots confirmed that intact Ala is indeed taken up by the roots, but that it is rapidly metabolized. C atoms other than from the carboxyl group and amino-N from Ala are assimilated in other amino acids, predominantly Glu, Gln, Asp, and Asn. Uptake rates reported by CSIA of the free amino acids are nevertheless much lower (16–64 times) than those reported by BSIA. Combining the use of isotopologues of amino acids with compound-specific isotope analysis helps reduce the bias in the assessment of organic N uptake and improves the understanding of organic N assimilation especially in the context of organic horticulture

The Aqueous and Methanol Extracts of Ficus asperifolia (Moraceae) Improve Reproductive Hormones Profile in High Fat Diet Induced Obese Rats

Ficus asperifolia (Moraceae), is a plant used as fertility booster. We investigated the effects of F. asperifolia extracts on sex hormones profile in high-fat diet (HFD)‑induced estrus cycle disturbances in rats. Female Wistar rats were fed either with HFD (n=161) or standard diet (n=8) for 10 weeks. After this period, 70 obese rats with abnormal estrus cycle were distributed into 14 groups of 5 animals each and treated for one and four weeks with distilled water (10 mg kg-1), Tween-80 (5%-10 mg kg-1), lutenyl (0.88 µg kg-1) and aqueous or methanol extract (100 or 500 mg kg-1) of F. asperifolia. At the end of each period, plasmatic estradiol and progesterone levels were determined. Acute toxicity parameters were also evaluated. HFD impaired reproductive hormones profile and estrous cycle after 10 weeks of treatment.F. asperifolia improved reproductive hormone profile by significantly increasing the plasmatic estradiol and progesterone levels. For instance, the plasmatic estradiol and progesterone levels were significantly increased (p<0.05-0.01) in rats treated with the aqueous (100 mg kg-1, four-weeks; 500 mg kg-1, one-week) or methanol (100 and 500 mg kg-1, four-weeks) extract of F. asperifolia. No toxic effects of F. asperifolia extracts were recorded. Our data support the traditional use of F. asperifolia as fertility enhancer