Processing And Characterization Of New Oxy-sulfo-telluride Glasses In The Ge-Sb-Te-S-O System

New oxy-sulfo-telluride glasses have been prepared in the GeSbTeSO system employing a two-step melting process which involves the processing of a chalcogenide glass (ChG) and subsequent melting with TeO2 or Sb2O3. The progressive incorporation of O at the expense of S was found to increase the density and the glass transition temperature and to decrease the molar volume of the investigated oxy-sulfo-telluride glasses. We also observed a shift of the visNIR cut-off wavelength to longer wavelength probably due to changes in Sb coordination within the glass matrix and overall matrix polarizability. Using Raman spectroscopy, correlations have been shown between the formation of Ge- and Sb-based oxysulfide structural units and the S/O ratio. Lastly, two glasses with similar composition (Ge20Sb6S64Te3O7) processed by melting the Ge23Sb7S70 glass with TeO2 or the Ge23Sb2S72Te4 glass with Sb2O3 were found to have slightly different physical, thermal, optical and structural properties. These changes are thought to result mainly from the higher moisture content and sensitivity of the TeO2 starting materials as compared to that of the Sb2O3. © 2010 Elsevier Inc. All rights reserved

L’anémie, un nouveau facteur de sévérité de la bronchiolite aiguë du nourrisson ?

International audienc

Monolithic Chalcogenide Optical Nanocomposites Enable Infrared System Innovation: Gradient Refractive Index Optics

The size and weight of conventional imaging systems is defined by costly non-planar lenses and the complex lens assemblies required to minimize optical aberrations. The ability to engineer gradient refractive index (GRIN) optics has the potential to overcome constraints of traditional homogeneous lenses by reducing the number of components in optical systems. Here, an innovative strategy to realize this goal based on monolithic GRIN media created in Ge-As-Se-Pb chalcogenide infrared nanocomposites is presented. A gradient heat treatment to spatially modulate the volume fraction of high refractive index Pb-rich nanocrystals within a glass matrix is utilized, providing a GRIN profile while maintaining an optical transparency. A first-ever correlation of material chemistry and microstructure, processing protocol, and optical property modification resulting in a prototype GRIN structure is presented. The integrated approach and mechanistic understanding illustrated by this versatile modification paradigm provides a platform for new optical functionalities in next-generation imaging applications

Evidence Of Spatially Selective Refractive Index Modification In 15GeSe2-45As2Se3-40PbSe Glass Ceramic Through Correlation Of Structure And Optical Property Measurements For GRIN Applications

Thermally-induced nucleation and growth of secondary crystalline phases in a parent glass matrix results in the formation of a glass ceramic. Localized, spatial control of the number density and size of the crystal phases formed can yield \u27effective\u27 properties defined approximately by the local volume fraction of each phase present. With spatial control of crystal phase formation, the resulting optical nanocomposite exhibits gradients in physical properties including gradient refractive index (GRIN) profiles. Micro-structural changes quantified via Raman spectroscopy and X-ray diffraction have been correlated to calculated and measured refractive index modification verifying formation of an effective refractive index, neff, with the formation of nanocrystal phases created through thermal heat treatment in a multi-component chalcogenide glass. These findings have been used to define experimental laser irradiation conditions required to induce the conversion from glass to glass ceramic, verified using simulations to model the thermal profiles needed to substantiate the gradient in nanocrystal formation. Pre-nucleated glass underwent spatially varying nanocrystal growth using bandgap laser heating, where the laser beam\u27s thermal profile yielded a gradient in both resulting crystal phase formation and refractive index. The changes in the nanocomposite\u27s micro-Raman signature have been quantified and correlated to crystal phases formed, the material\u27s index change and the resulting GRIN profile. A flat, threedimensional (3D) GRIN nanocomposite focusing element created through use of this approach, is demonstrated

Klebsiella pneumoniae and Klebsiella oxytoca meningitis in infants. Epidemiological and clinical features

International audienceBackground: The incidence of meningitis caused by Klebsiella pneumoniae (Kp) and Klebsiella oxytoca (Ko) in high-income countries is unknown, and no series have been published to date.Methods: We conducted a nationwide multicenter observational study in France between 2006 and 2016. All children from the French national registry for paediatric bacterial meningitis under the age of 1 year and hospitalized for Kp or Ko meningitis were included. Virulence factors of four Klebsiella spp. strains were explored by whole genome sequencing.Results: Of 1859 cases of meningitis in children under the age of 1 year, 13 cases (0.7%) of Klebsiella spp. meningitis (nine for Kp meningitis and four for Ko meningitis) were registered in the French national registry. Three of the patients died and 50% of the survivors had developmental delays.Conclusions: Prematurity, low birth weight, and congenital anomalies of the urinary tract appear to be risk factors for Klebsiella spp. meningitis as well as virulence factors of the strain

Engineering Novel Infrared Glass Ceramics For Advanced Optical Solutions

Advanced photonic devices require novel optical materials that serve specified optical function but also possess attributes which can be tailored to accommodate specific optical design, manufacturing or component/device integration constraints. Multi-component chalcogenide glass (ChG) materials have been developed which exhibit broad spectral transparency with a range of physical properties that can be tuned to vary with composition, material microstructure and form. Specific tradeoffs that highlight the impact of material morphology and optical properties including transmission, loss and refractive index, are presented. This paper reports property evolution in a representative 20 GeSe2-60 As2Se3-20 PbSe glass material including a demonstration of a 1D GRIN profile through the use of controlled crystallization