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491.
Amar BelliliNicolas David Bruno VandameQingxiao Wang Yannick GoutilleEmmanuel Richaud 《Polymer Testing》2012,31(2):236-247
This paper reports a study of mineral oil diffusion through a filled ethylene-vinyl acetate crosslinked polymer, together with some comparisons with aliphatic linear hydrocarbons. Permeation was monitored by classical gravimetric measurements leading to values of solubility and diffusion coefficient at several temperatures ranging from 20 to 120 °C. Diffusion coefficients display a change in activation energy at at ca. 70 °C for mineral oils but not for simple hydrocarbons. The values obtained were discussed regarding available structure-diffusivity relationships and diffusion models derived from free volume theory. A relationship between penetrant evaporation temperature and its diffusivity was observed and tentatively justified. 相似文献
492.
Melissa C. Menard Amar B. Karki Philip W. Adams David P. Young 《Journal of solid state chemistry》2010,183(9):1935-1942
We report the flux growth and characterization of Ln2Ag1−xGa10−y (Ln=La, Ce), a disordered variant of the Ce2NiGa10 structure type. Single crystals of La2Ag1−xGa10−y (x∼0.3; y∼0.6) and Ce2Ag1−xGa10−y (x∼0.3; y∼0.9) were grown by the self-flux method and characterized using single-crystal X-ray diffraction. Transport measurements of Ce2Ag1−xGa10−y (x∼0.3; y∼0.9) reveal metallic behavior with a transition at 3 K. Magnetic measurements indicate antiferromagnetic ordering at 3 K of localized Ce3+ moments for Ce2Ag1−xGa10−y. Magnetoresistance is positive with a maximum value of 16% at 9 T. La2Ag1−xGa10−y exhibits metallic behavior with magnetic susceptibility showing temperature independent paramagnetism. We will compare Ce2Ag1−xGa10−y (x∼0.3; y∼0.9) to Ce2NiGa10 to examine the effects of transition metal substitution and to the related Ce(Ag,Ga)4 phase to examine the effects of crystal structure on the physical properties. 相似文献
493.
We study the bifurcation of limit cycles from the periodic orbits of a linear differential system in R4 in resonance 1:n perturbed inside a class of piecewise linear differential systems, which appear in a natural way in control theory. Our main result shows that at most 1 limit cycle can bifurcate using expansion of the displacement function up to first order with respect to a small parameter. This upper bound is reached. For proving this result we use the averaging theory in a form where the differentiability of the system is not needed. 相似文献
494.
495.
Full-field optical coherence microscopy (FF-OCM) and optically sectioned fluorescence microscopy are two imaging techniques that are implemented here in a novel dual modality instrument. The two imaging modalities use a broad field illumination to acquire the entire field of view without raster scanning. Optical sectioning is achieved in both imaging modalities owing to the coherence gating property of light for FF-OCM, and a structured illumination setup for fluorescence microscopy. Complementary image data are provided by the dual modality instrument in the context of biological tissue screening. FF-OCM imaging modality shows the tissue microarchitecture, while fluorescence microscopy highlights specific tissue features with cellular-level resolution by using targeting contrast agents. Complementary tissue morphology and biochemical features could potentially improve the understanding of cellular functions and disease diagnosis. 相似文献
496.
Dr. Emmanuel Picheau Dr. Ferdinand Hof Dr. Sara Amar Dr. Alain Derré Dr. Alain Pénicaud 《Angewandte Chemie (International ed. in English)》2023,62(20):e202303060
External diffusion may be exploited as a tool to purify materials in a way thought to be inaccessible from a chemical reactivity point of view. A mixture of two carbonaceous materials, graphite and carbon black, are thermally oxidized in either i) outside total diffusion-limited regime or ii) total diffusion-limited regime. Depending on the treatment applied it is possible to purify either graphite, a trivial task, or carbon black, a task thought impossible. Introducing geometrical selectivity, controlled total diffusion-limited chemistry exceeds by far the field of carbon materials and can be used as an engineering tool for many materials purification, original synthesis, or to introduce asymmetry in a system. Several examples for direct applications of the findings are mentioned. 相似文献