5 research outputs found

    Activities of extracts from saponin-containing plants on sheep erythrocytes, Tetrahymena pyriformis and Rumen protozoa

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    International audienceAs the effects of saponins in the rumen are due to their membrane-disrupting ability on protozoa, the activities of extracts from saponin containing plants were determined on erythrocytes, Tetrahymena pyriformis and rumen protozoa. Inhibition of Tetrahymena pyriformis were found to be correlated (R2=0.54) with 50% hemolysis. The extracts supplemented to a standard feed, showed null to remarkable in vitro activity on rumen protozoa. With -51% and -41% protozoa inhibition, Primula veris and Chenopodium quinoa might have the potential to improve ammonia utilization in ruminants, meaning less excreted nitrogen and less environmental impact.</p

    Investigation of the relationships between mechanical properties and microstructure in a Fe-9%Cr ODS steel

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    Ferritic-martensitic Oxide Dispersion Strengthened (ODS) steels are potential materials for fuel pin cladding in Sodium Fast Reactor (SFR) and their optimisation is essential for future industrial applications. In this paper, a feasibility study concerning the generation of tensile specimens using a quenching dilatometer is presented. The ODS steel investigated contains 9%Cr and exhibits a phase transformation between ferrite and austenite around 870 °C. The purpose was to generate different microstructures and to evaluate their tensile properties. Specimens were machined from a cladding tube and underwent controlled heat treatments inside the dilatometer. The microstructures were observed using Electron Backscatter Diffraction (EBSD) and tensile tests were performed at room temperature and at 650 °C. Results show that a tempered martensitic structure is the optimum state for tensile loading at room temperature. At 650 °C, the strengthening mechanisms that are involved differ and the microstructures exhibit more similar yield strengths. It also appeared that decarburisation during heat treatment in the dilatometer induces a decrease in the mechanical properties and heterogeneities in the dual-phase microstructure. This has been addressed by proposing a treatment with a much shorter time in the austenitic domain. Thereafter, the relaxation of macroscopic residual stresses inside the tube during the heat treatment was evaluated. They appear to decrease linearly with increasing temperature and the phase transformation has a limited effect on the relaxation