Search results for " Glass"
showing 10 items of 409 documents
Fibres optiques à coeur supendu en verre d'oxyde de tellure et génération d'effets non linéaires dans l'infrarouge au-delà de 2 microns
2012
The work reported in this thesis deals with the fabrication of suspended core tellurite microstructured optical fibers (MOFs) for supercontinuum generation beyond 2 µm. In order to reach our aim, we first studied thermal and optical properties of TeO2-ZnO-R2O and TeO2-WO3-R2O (where R = Li, Na and K) glasses. The glass 80TeO2-10ZnO-10Na2O (molar %) has been chosen in order to make MOFs for characterization of the generated non linear optical effects. Synthesis performed under dry and oxidative atmosphere allowed us to reduce the hydroxyl groups concentration by a factor of 30 compared to fabrication in air atmosphere. Use of dehydrating agents (ZnF2 and TeCl4) allowed to reduce again the OH…
Bioactive glass ions as strong enhancers of osteogenic differentiation in human adipose stem cells.
2015
Bioactive glasses are known for their ability to induce osteogenic differentiation of stem cells. To elucidate the mechanism of the osteoinductivity in more detail, we studied whether ionic extracts prepared from a commercial glass S53P4 and from three experimental glasses (2-06, 1-06 and 3-06) are alone sufficient to induce osteogenic differentiation of human adipose stem cells. Cells were cultured using basic medium or osteogenic medium as extract basis. Our results indicate that cells stay viable in all the glass extracts for the whole culturing period, 14 days. At 14 days the mineralization in osteogenic medium extracts was excessive compared to the control. Parallel to the increased mi…
Ultramorphology and dentine permeability changes induced by prophylactic procedures on exposed dentinal tubules in middle dentine
2010
Objectives: The purpose of this study was to evaluate the changes in dentinal permeability (i.e. hydraulic conductance) after prophylactic treatments performed using prophy-powders with air-polishing system or prophy-pastes on exposed middle dentine. The changes in dentine morphology were evaluated by SEM. Study design: Commercial prophylactic pastes and air-polishing powders were tested in this study. Dentine discs from human third molars were used to study the quantitative reduction of the dentine permeability under simulated pulpal pressure (20 cm H 2O). Further specimens were gold-coated and analysed using observed a SEM. Results: The results of this study showed different dentine perme…
Surface-induced order and diffusion in 5CB liquid crystal confined to porous glass.
2001
Liquid crystals confined into small cavities are known to have a weak orientational order even above the nematic-isotropic transition temperature. The surface-induced order and molecular dynamics in this temperature range are studied with the aid of deuteron NMR spectra, spin relaxation times T(1) and T(2,) proton dipolar-correlation effect, and direct measurements of the effective diffusion coefficient for the liquid crystal 5CB confined to controlled-pore glasses. Our results show that an arrangement of molecules parallel to the wall is induced by local molecular interactions between the liquid crystal and solid, resulting in a weak and temperature independent surface order parameter, S(0…
Superfluid density and quasi-long-range order in the one-dimensional disordered Bose–Hubbard model
2015
We study the equilibrium properties of the one-dimensional disordered Bose-Hubbard model by means of a gauge-adaptive tree tensor network variational method suitable for systems with periodic boundary conditions. We compute the superfluid stiffness and superfluid correlations close to the superfluid to glass transition line, obtaining accurate locations of the critical points. By studying the statistics of the exponent of the power-law decay of the correlation, we determine the boundary between the superfluid region and the Bose glass phase in the regime of strong disorder and in the weakly interacting region, not explored numerically before. In the former case our simulations are in agreem…
Micro‐tomographic characterization of composite recycled glass‐silicone foams for applications in civil engineering
2019
Noninvasive X‐ray micro‐computed tomography was applied for a complete quantitative and qualitative analysis of the cellular structure of composite foams constituted by a silicone matrix and a glass production waste filler. Composite foams with different glass filler weight content in the range 0–80% were synthesized and characterized. The tomographic analysis was employed in order to assess the structural heterogeneities, void fraction values, and bubble size distribution for all composite foams. The 3D micro‐CT images analysis, performed at different cross‐sections, highlighted heterogeneous cell growth or more elongated cells in the case of low and high filler content foams, respectively…
A multivariate statistical approach of X-ray fluorescence characterization of a large collection of reverse glass paintings
2019
We present an X-ray fluorescence spectroscopy (XRF) study combined with a multivariate approach that allow to detect compositional differences and similarities among the glass supports of a large set of reverse glass paintings belonging to the collection of the Mistretta museum. Reverse painting on glass is an old decorative technique used since the Roman time consisting in applying a cold paint layer on the reverse side of a glass support. The collection shows a large spreading of provenience and dating of the items. In consideration of the current classification solely based on stylistic criteria, we applied a multivariate analysis on the XRF measurements data set to find a more objective…
Philip Glass: Company; "Low" Symphony / Shostakovich: La nuova Babilonia (suite) / Nino Rota: La strada (suite dal balletto)
1994
L'articolo è stato realizzato in occasione della prima esecuzione italiana della "Low" Symphony di Philip Glass (Gibellina, 21 giugno 1994) e traccia un breve profilo del compositore, soffermandosi sulla genesi e i caratteri dell'opera.
Ordered mesoporous silicas as host for the incorporation and aggregation of octanuclear nickel(ii) single-molecule magnets: a bottom-up approach to n…
2006
Silica-based mesoporous materials have been employed as the support host for a suitably designed small octanuclear nickel(II) guest complex with a moderately anisotropic S = 4 ground spin state (D = −0.23 cm−1), which behaves as a single-molecule magnet at low temperature (TB = 3.0 K). Both unimodal MCM-41 and bimodal UVM-7 porous silica provide appropriate template conditions for the incorporation and aggregation of the Ni8 complex precursor into larger complex aggregates, showing slow relaxation of the magnetization at higher blocking temperatures than the crystalline material. By playing with the initial complex vs. silica concentration, two series of samples with varying complex loading…
Selenium Nanoparticles Synthesized via a Facile Hydrothermal Method
2012
Crystalline selenium nanostructures were synthesized from the reaction of a GeSe3 glass with water at 85°C for 144 hours. The hydrolysis of the Ge-Se bonds releases Se fragments in the solution where they form a colloidal suspension of amorphous nanospheres. The later evolve toward a more stable hexagonal phase (trigonal) leading to the anisotropic growth of one-dimensional monocrystalline structures. Filaments, bars and tubes of monocrystalline trigonal selenium were obtained with diameters ranging from 10 nm to 1 µm and aspect ratio up to 180. This simple process in aqueous solution opens new perspectives for the synthesis of 1D nanoparticles of trigonal selenium at large scale.