682 research outputs found

    Synthesis of nitroxyl radical by direct nucleophilic functionalization of a C-H bond in the azadiene systems

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    Cyclic dinitrones underwent nucleophilic substitution of the hydrogen atom in the reaction with a paramagnetic carbanion, the lithium derivative of 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide, to give polyfunctional nitronyl nitroxyls. © 2012 Springer Science+Business Media New York

    Bound states in the continuum in symmetric and asymmetric photonic crystal slabs

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    We develop a semi-analytical model to describe bound states in the continuum (BICs) in photonic crystal slabs. We model leaky modes supported by photonic crystal slabs as a transverse Fabry-Perot resonance composed of a few propagative Bloch waves bouncing back and forth vertically inside the slab. This multimode Fabry-Perot model accurately predicts the existence of BICs and their positions in the parameter space. We show that, regardless of the slab thickness, BICs cannot exist below a cut-off frequency, which is related to the existence of the second-order Bloch wave in the photonic crystal. Thanks to the semi-analyticity of the model, we investigate the dynamics of BICs with the slab thickness in symmetric and asymmetric photonic crystal slabs. We evidence that the symmetry-protected BICs that exist in symmetric structures at the {\Gamma}-point of the dispersion diagram can still exist when the horizontal mirror symmetry is broken, but only for particular values of the slab thickness

    Фенотипы больных хронической обструктивной болезнью легких и исследование ECLIPSE: первые результаты

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    Phenotypes of chronic obstructive pulmonary disease and the ECLIPSE study: preliminary results.Фенотипы больных хронической обструктивной болезнью легких и исследование ECLIPSE: первые результаты
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