Evaluation de la sensibilité de trois espèces de glossines d'élevage au D.D.T. et à l'Endosulfan déterminée au moyen des applicateurs capillaires de l'O.M.S.

La sensibilité de trois espèces de glossines d'élevage (G. tachinoides, G. m. morsitans, G. p. gambiensis) au D.D.T. et à l'Endosulfan, a été évaluée par applications topiques, au moyen du tube applicateur capillaire de l'O.M.S. Celui-ci, d'un maniement très simple, permet d'aboutir à des résultats comparables, qualitativement, à ceux obtenus par d'autres auteurs au moyen d'un matériel plus sophistiqué. L'espèce de glossine la plus sensible à l'Endosulfan est G. tachinoides; la résistance de G. m. morsitans est intermédiaire entre celle de G. tachinoides et celle de G. p. gambiensis. Par rapport à l'Endosulfan, le D.D.T. présente une toxicité très faible puisque les D.L. 50 obtenues avec cet insecticide sont environ vingt fois inférieures. Des trois espèces de glossines utilisées, G. tachinoides est la plus sensible aux deux insecticides. La mortalité chez G. m. morsitans est intermédiaire entre G. tachinoides et G. p. gambiensi

Analysis of the film stacking processing parameters for PLLA/flax fibre biocomposites

International audienceNowadays, the market demand for environmentally friendly materials is rapidly increasing. Biodegradable fibres and biodegradable polymers mainly extracted from renewable resources are expected to be a major contribution to the production of new industrial high performance biodegradable composites, partially solving the problem of waste management. At the end of its lifetime, a structural biodegradable composite can be crushed and recycled through a controlled industrial composting process. Bodros et al. [1] showed that biodegradable PLLA (L-polylactide acid)/flax fibres mat composites exhibiting specific tensile properties equivalent to glass fibre polyester composites can be manufactured by an un-optimised film stacking process. In our study, the process has been investigated more extensively. Indeed, the compaction of flax mats requires a higher load than for glass mats of similar areal weight. The transverse permeability of flax mats has also been shown to be lower than for glass mats. In both cases, this is due to a higher degree of entanglement of the flax fibres within the mat. However, the range of permeability and compressibility values of the flax mats are well within the values that allow a good through-thethickness impregnation. Flax fibres cannot sustain long exposures at the impregnation temperature of the mats by PLLA resin. Through-the-thickness impregnation of flax mats processes such as film stacking are more suitable than in-plane impregnation processes such as Resin Transfer Molding because the flow of resin is limited on short distances and allows short times of impregnation

Theoretical and Experimental Modelling of Bubble Formation with Connected Capillaries in Liquid Composite Moulding Processes

The void prediction in LCM processes sparks off interest within the composite material industry because it is a significant issue to keep the expected mechanical properties. The liquid properties, the preform geometry and the flow conditions impact the quantity of void entrapped inside the final product. The complex geometry of the reinforcement due to the arrangement of the bundles and the fibres is a key point to understand and quantify this phenomenon. This paper deals with both simple model networks which can occur inside a fabric representing connected capillaries, so-called "Pore Doublet Model (PDM)". A first is considering two capillaries converging on a node (T-junction) and a second is representing two capillaries interconnected with a supplying principle. These configurations can affect locally the evolution of flow fronts. First, experiments of bubble formed in a T-junction device have been performed and studied. Then a theoretical approach was proposed to forecast microvoid and macrovoid formation, by taking into account a supplying principle and arranged Washburn equation in forced filling.Comment: 8 pages; 11th International Conference Flow Processing in Composite Materials, Auckland : New Zealand (2012

Synthesis and characterization of La_0.8Sr_1.2Co_0.5M_0.5O_4-? (M=Fe, Mn)

The M4+-containing K2NiF4-type phases La0.8Sr1.2Co0.5Fe0.5O4 and La0.8Sr1.2Co0.5Mn0.5O4 have been synthesized by a sol-gel procedure and characterized by X-ray powder diffraction, thermal analysis, neutron powder diffraction and Mössbauer spectroscopy. Oxide ion vacancies are created in these materials via reduction of M4+ to M3+ and of Co3+ to Co2+. The vacancies are confined to the equatorial planes of the K2NiF4-type structure. A partial reduction of Mn3+ to Mn2+ also occurs to achieve the oxygen stoichiometry in La0.8Sr1.2Co0.5Mn0.5O3.6. La0.8Sr1.2Co0.5Fe0.5O3.65 contains Co2+ and Fe3+ ions which interact antiferromagnetically and result in noncollinear magnetic order consistent with the tetragonal symmetry. Competing ferromagnetic and antiferromagnetic interactions in La0.8Sr1.2Co0.5Fe0.5O4, La0.8Sr1.2Co0.5Mn0.5O4 and La0.8Sr1.2Co0.5Mn0.5O3.6 induce spin glass properties in these phases

Void Prediction During Liquid Composite Molding Processes: Wetting and Capillary Phenomena

The aim of this work is to contribute in improving fibrous preforms impregnation for Liquid Composite Molding (LCM) processes. The void prediction in LCM sparks off interest within the Composite Material elaboration because it represents a significant issue to keep the expected mechanical properties of the final product. The liquid properties, the preform geometry and the flow conditions impact the void or bubble entrapped inside and outside the yarns. Nevertheless, due to the complex geometry of the reinforcement, experimental characterization of bubble formation remains delicate. Thus, our study deals with two simple model networks representing connected pores so called "Pore Doublet Model". A first is considering two capillaries converging on a node (T-junction) and a second is representing two capillaries interconnected with a supplying principle. In this paper, we emphasize on microfluidic and millifluidic approaches where wetting and capillary forces are significant during bubble formation mechanism.Comment: 8 pages; 15th European Conference on Composite Materials, Venise : Italy (2012