Recherche de cancer occulte chez des patients présentant une maladie thromboembolique (intérêt du scanner abdomino-pelvien)

PARIS6-Bibl.Pitié-Salpêtrie (751132101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

ETUDE DE MONOCRISTAUX DE KTIOPO 4 SOUS CHAMP ELECTRIQUE (MESURES ELECTRIQUES, OBSERVATIONS OPTIQUES ET IMAGERIE PAR DIFFRACTION AUX RAYONS X)

GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Combined x-ray imaging and diffraction study of light-induced distortions in Fe:LiNbO3

A real-time investigation of the light-induced deformation on Fe:LiNbO3 crystals was performed by taking advantage of both the high flux and the detector system (FRELON CCD camera) available at a modern synchrotron radiation source like the ESRF. The observed contrast and effective misorientation after illumination of a Z-cut crystal are mainly due to (00l) lattice planes tilts. Considering the coupling of the bulk photovoltaic field and the converse piezoelectric effect, we develop a 'parallel plate condenser'-like macroscopic model of the distortion generated by the visible light beam. Calculation of the effective misorientation at the edges of the illuminated region gives values of the order of ±20 arcsec which are consistent with our experimental data. © 2001 IOP Publishing Ltd

Notice sur la fièvre typhoïde (rémittente vermineuse) qui a régné dans les environs de Cusset, pendant l'automne 1859 / par L.-P. Lorut,...

Avec mode text

Retrieving overlapping crystals information from TEM nano-beam electron diffraction patterns

International audienceThe diffraction patterns acquired with a transmission electron microscope (TEM) contain Bragg reflections related to all the crystals superimposed in the thin foil and crossed by the electron beam. Regarding TEM-based orientation and phase characterisation techniques, the nondissociation of these signals is usually considered as the main limitation for the indexation of diffraction patterns. A new method to identify the information related to the distinct but overlapped grains is presented. It consists in subtracting the signature of the dominant crystal before reindexing the diffraction pattern. The method is coupled to the template matching algorithm used in a standard automated crystal orientation mapping tool (ACOM-TEM). The capabilities of the approach are illustrated with the characterisation of a NiSi thin film stacked on a monocrystalline Si layer. Then, a subtracting-indexing cycle applied to a 70 nm thick thin foil containing polycrystalline tungsten electrical contacts shows the capability of the technique to recognise small nondominant grains

TEM illumination settings study for optimum spatial resolution and indexing reliability in crystal orientation mappings

International audienceThe spatial resolution and the indexing quality obtained with an automated orientation and phase mapping tool are analyzed for different Transmission Electron Microscope (TEM) illumination settings. The electron probe size and convergence angle are studied for two TEM configuration modes referred as microprobe and nanoprobe modes. Using a 10 mu m C-2 aperture in a FEI Tecnai F20 (S)TEM, the nanoprobe mode is used to get a small convergent electron beam while the microprobe mode provides a nearly parallel illumination at the cost of a larger probe size. The nanoprobe configuration enables to increase the spatial resolution (similar to 1 nm vs 3 nm) but also affects the fraction of mis-indexed points (15% vs 1%). Indexing errors are attributed to the increase by a factor of three of the convergence angle with respect to the microprobe mode. While intermediate optimum settings may be found and are potentially achievable on electron microscopes providing a `free lens' control or a larger choice of C-2 apertures, it is emphasized that the spatial resolution cannot be considered without reference to the indexing quality and, consequently to the convergence angle. (C) 2016 Elsevier Ltd. All rights reserved

Te and Ge solid-state reaction: comparison between the 2D and 3D growth of α-GeTe

International audienceIn this work, solid-state a-GeTe growth is studied during the reactive diffusion of a polycrystalline thin film of hexagonal Te deposited on an amorphous Ge thin film (Te-on-Ge) using in situ X-ray diffraction, in situ transmission electron microscopy, and atom probe tomography. After deposition, an amorphous intermixing layer is observed between the Te and Ge layers. a-GeTe is found to form a 2D layer between the deposited Ge and Te layers during growth, with a thickness increasing linearly with time as predicted by the linear-parabolic model for interfacial reaction limited growth. The activation energy of nucleation and interfacial reactions was determined from different isothermal annealing. The obtained results are compared to the observations previously reported during a-GeTe 3D growth in a sample made of an amorphous Ge layer deposited on a polycrystalline Te layer (Ge-on-Te) in the same magnetron sputtering system under the same conditions