Éditeur(s) : HAL CCSD
Résumé : Composite materials incorporating vegetable fibres have known an increasingly interest during the past few decades. These environmental friendly materials are low-cost and offer advantages such as reduction of electrical consumption by air conditioning. Moreover, the use of vegetable fibres in replacement of synthetic fibre is interesting in developing countries where the availability of tropical plants and agricultural waste is important. This paper presents an initial investigation on the use of a construction material, composed of cement and pre-treated (heat or alkaline treatments) sugar cane bagasse fibres. The purpose of this study is to analyse the effect of fibre content and treatment on thermal conductivity, specific heat, flexural strength and density. The addition of retified fibres reduces composites thermal conductivity and yields a weaker specific heat in comparison with composites made with alkaline fibres. From mechanical point of view, composites made with alkaline fibres have a better flexural strength than others.
12th International Inorganic-bonded Fiber Composites Conference
Aalborg, Denmark

hal-00807543
https://hal.univ-antilles.fr/hal-00807543

Résumé : Aujourd’hui, il est indispensable de découvrir de nouveaux agents thérapeutiques pour faire face à l’expansion des infections fongiques humaines. D’un autre côté, certains arbres amazoniens ont acquis des moyens pour se protéger contre la dégradation fongique. Ces composés d’origine végétale pourraient donc être des candidats potentiels au développement de composés antifongiques. Il est ainsi exposé dans ce travail la sélection bio-inspirée et la récolte d’espèces d’arbres amazoniens résistants à la dégradation fongique ; à partir desquelles il est proposé d’isoler, d’identifier et de valoriser les métabolites responsables de la durabilité naturelle et d’étudier leurs propriétés sur des champignons pathogènes humains. Cette étude a conduit à l’isolement de molécules inédites apportant un complément d’information chimiotaxonomique pour les espèces étudiées. De plus, il a pu être mis en avant deux molécules pouvant devenir des composés pertinents pour le développement de traitements antimycotiques.
It is now essential to discover new therapeutic agents against the increase of human fungal infections. On the other hand, some Amazonian trees have succeeded to develop a chemical defense arsenal to protect themselves against fungal degradation. These compounds of plant origin could become potential candidates for the development of antifungal compounds for the treatment of human fungal diseases. Therefore, this manuscript describes the bio-inspired selection and collection of Amazonian tree species capable of specializing a highly fungiresistant wood; from which it is proposed to isolate, identify and valorize the secondary metabolites responsible for the natural durability, and study their properties on human pathogenic fungi. Ultimately, this study led to the isolation of new compounds and providing additional important chemotaxonomic information for the species studied. In addition, it as been established that two compounds could be relevant for the development of antimitotic therapies.

http://www.theses.fr/2011AGUY0467/document

Éditeur(s) : HAL CCSD
Résumé : 1 page
The main aim of this study, co-funded by BRGM, Regional Council of Guadeloupe, European Union, ADEME and UAG, was to examine the silica deposition mechanisms and estimate their deposition kinetics at acidic and basic pH conditions, during the cooling from 260 to 25°C of separated waters, discharged from production wells, located in the Bouillante geothermal field. The acquisition of this type of information is very useful not only for the geothermal exploitation but especially, if production fluids are re-injected in the ground, as this is envisaged in the Bouillante geothermal field. The different on site experiments showed that, in these conditions, the silica deposition was always initiated by a silica polymerization mechanism and the formation of a white colloidal gel, which slowed down the silica precipitation. In agreement with the literature data, this polymerization mechanism is characterized by an order 2 kinetic law, strongly dependant on pH. The determination of the specific surface area by specific mercury porosimetry for this gel (250 m2/g) in the UAG laboratories, allowed estimating the corresponding kinetic constant at 25°C. Other experiments at different final temperatures (50, 75 and 100°C) are necessary in order to define this constant as a function of the temperature. The silica precipitation under amorphous silica form was observed much later, after the polymerization stage, and only in particular conditions (long time of atmospheric exposure, water stagnation...). The pH of the Bouillante geothermal fluid is estimated to be close to 5.3±0.3, at 260°C, in the reservoir conditions. If this parameter, very influent on the kinetics of silica deposition, can be preserved at values less than 7 during the re-injection of the production fluids in the ground at relatively high temperatures (150-160°C), it is strongly probable that no chemical treatment is necessary to avoid silica precipitation.
19ème Conférence Géologique de la Caraïbe - 2011
Gosier, Guadeloupe, France

hal-00575943
https://hal-brgm.archives-ouvertes.fr/hal-00575943