74 research outputs found
Echocardiographie de l'insuffisance mitrale ischémique (approche tridimensionnelle exhaustive)
No full textLYON1-BU Santé (693882101) / SudocSudocFranceF
Percutaneous femoral artery access with Prostar device for innovative mitral and aortic interventions
No full textValve replacement in children: A challenge for a whole life
No full textSummaryValvular pathology in infants and children poses numerous challenges to the paediatric cardiac surgeon. Without question, valvular repair is the goal of intervention because restoration of valvular anatomy and physiology using native tissue allows for growth and a potentially better long-term outcome. When reconstruction fails or is not feasible, valve replacement becomes inevitable. Which valve for which position is controversial. Homograft and bioprosthetic valves achieve superior haemodynamic results initially but at the cost of accelerated degeneration. Small patient size and the risk of thromboembolism limit the usefulness of mechanical valves, and somatic outgrowth is an universal problem with all available prostheses. The goal of this article is to address valve replacement options for all four valve positions within the paediatric population. We review current literature and our practice to support our preferences. To summarize, a multitude of opinions and surgical experiences exist. Today, the valve choices that seem without controversy are bioprosthetic replacement of the tricuspid valve and Ross or Ross-Konno procedures when necessary for the aortic valve. On the other hand, bioprostheses may be implanted when annular pulmonary diameter is adequate; if not or in case of right ventricular outflow tract discontinuity, it is better to use a pulmonary homograft with the Ross procedure. Otherwise, a valved conduit. Mitral valve replacement remains the most problematic; the mechanical prosthesis must be placed in the annular position, avoiding oversizing. Future advances with tissue-engineered heart valves for all positions and new anticoagulants may change the landscape for valve replacement in the paediatric population
Luminescent properties of GeOx thin films and GeO/SiO2 heterostructures modified with swift heavy ions
No full textInternational audienc
Elaboration and characterization of thin layers of SiP lamellar alloys
No full textInternational audienceIn contrast to III-V or II-VI semiconductor alloys, group IV-V alloys have been the subject of much less attention up to now. Theoretical calculations have shown that bulk SiP is an indirect bandgap semiconductor which becomes direct in its 2D form. Moreover, bulk SiP is a lamellar alloy that can be exfoliated, which is of particular interest for new applications in optoelectronics. In this work, we investigate SiPx thin films prepared by evaporation under high vacuum. The films were prepared by co-evaporation of Si from an e-beam gun and P from a GaP decomposition source. The structural and optical properties were investigated by means of X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), vibrational spectroscopies (Infrared and Raman) and photoluminescence spectroscopy. After annealing at 1100°C, the structural characterizations reveal the presence of lamellar SiP grains crystallizing in an orthorhombic structure which coexist with Si polycrystals. To further characterize the SiP alloy, DFT calculations have been carried out to get a better understanding of the features observed in both infrared and Raman spectra. The calculated spectra are found to be in excellent agreement with the experimental results. Moreover, temperature dependent photoluminescence measurements strongly suggest that SiP is an indirect bandgap semiconductor with a bandgap energy of 1.47 eV. The obtained value is in good agreement with theoretical values found in the literature
Size Dependence of Plasmonic Response in Phosphorus-Doped Si Nanocrystals: Implication for Infrared Plasmonics
No full textInternational audienceHighly doped semiconductor nanocrystals are of great interest for applications in nanophotonics and appear as an exciting alternative for infrared plasmonics with detection and identification of molecules, covering applications in biology, medicine, air quality control, sanitary control, and safety issues. Among the main parameters that influence optical properties and plasmonic response, the nanocrystals size plays a major role. In this work, we report on the influence of the silicon nanocrystals size on the localized surface plasmon resonance obtained in n-type Si nanocrystals embedded in a silicon dioxide matrix. The size control of phosphorus-doped Si nanocrystals was achieved by using a (SiO/SiO2) multilayer architecture. In this study, the nanocrystal diameter is varied from 7 to 16 nm while the P content is kept constant at 0.9 atom %. Here, we demonstrate that the mid-infrared plasmonic absorption exhibits a redshift as well as a broadening as the nanocrystal diameter decreases from 16 to 7 nm. The plasmonic response was successfully modelled in the framework of the Mie theory, considering the Drude model and a size-dependent scattering of free carriers. The redshift of the plasmon is explained not only by a size-dependent scattering but also by a size-dependent doping efficiency. Both charge carrier mobilities and free carrier densities are found to vary between 17 and 28 cm 2 V -1 s -1 and between 1.89×10 20 cm -3 and 2.6×10 20 cm -3 , respectively. In this work, we shed light on the key role of the Si/SiO2 interface that needs to be optimized to reach plasmonic properties in very small nanocrystals that could support quantum plasmonics
On the Formation of Amorphous Ge Nanoclusters and Ge Nanocrystals in GeSixOy Films on Quartz Substrates by Furnace and Pulsed Laser Annealing
No full textInternational audienc
Light-emitting defects formed in GeO/SiO2 heterostructures with assistance of swift heavy ions
No full textInternational audienc
Infrared photoluminescence from GeSi nanocrystals embedded in a germanium-silicate matrix.
No full textÉquipe 104 : NanomatériauxInternational audienceWe investigate the structural and optical properties of GeO/SiO multilayers obtained by evaporation of GeO and SiO powders under ultrahigh vacuum conditions on Si(001) substrates. Both Raman and infrared absorption spectroscopy measurements indicate the formation of GeSi nanocrystals after postgrowth annealing at 800°C. High-resolution transmission electron microscopy characterizations show that the average size of the nanocrystals is about 5 nm. For samples containing GeSi nanocrystals, photoluminescence is observed at 14 K in the spectral range 1500-1600 nm. The temperature dependence of the photoluminescence is studied
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