The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Khrustov Vladimir - One of the best experts on this subject based on the ideXlab platform.
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Growth of optical grade Yttrium Oxide single crystal via ceramic technology
Optical Materials, 2012Co-Authors: Ivanov Maxim, Vyukhina Irina, Khrustov VladimirAbstract:Abstract To sinter neodymium doped Yttrium Oxide (NDY) singe crystal several successive technologies: laser synthesis of NDY nanopowder, pulsed magnetic compacting of the powder and two stage vacuum sintering were used. With the help of abnormal grain growth samples of NDY single crystal were produced. Conditions that are necessary for abnormal grain growth in Yttrium Oxide as well to grow the optical grade single crystal are discussed.
Sergey Piletsky - One of the best experts on this subject based on the ideXlab platform.
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Biocompatibility and biodistribution of surface-modified Yttrium Oxide nanoparticles for potential theranostic applications
Environmental Science and Pollution Research, 2019Co-Authors: Hossam Sayour, Samr Kassem, Joanna Czulak, Medhat Mohamed, Francesco Canfarotta, Sergey PiletskyAbstract:The surface of ultrafine Yttrium Oxide nanoparticles (NPs) with mean size of 7–8 nm was modified with a functional polymer layer to improve their dispersion and impart fluorescent properties for imaging purposes. Surface functionalization was achieved by silanization of Yttrium Oxide NPs with 3-trimethoxysilylpropyl methacrylate followed by grafting of a co-polymer made of acrylic acid (AA) and ethylene glycol methacrylate phosphate (EGMP). The polymer shell decreases the surface energy of NPs, enhances their polarity, and, as a result, improves their colloidal stability. The synthesized NPs are capable of scavenging free radicals and for this reason have therapeutic potential that warrants further investigations. Furthermore, these stabilized core–shell NPs showed a very low cytotoxicity, confirming that the polymer shell sensibly improves the biocompatibility of bare Yttrium Oxide NPs, which are otherwise toxic on their own. Poly-EGMP Yttrium NPs proved to be safe up to 0.1 mg/g body weight in 1 month old Sprague–Dawley rats, showing also the ability to cross the blood–brain barrier short time after tail injection. The surface modification of Yttrium NPs here described allows these NPs to be potentially used in theranostics to reduce neurodegenerative damage due to the heat stress.
Ivanov Maxim - One of the best experts on this subject based on the ideXlab platform.
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Growth of optical grade Yttrium Oxide single crystal via ceramic technology
Optical Materials, 2012Co-Authors: Ivanov Maxim, Vyukhina Irina, Khrustov VladimirAbstract:Abstract To sinter neodymium doped Yttrium Oxide (NDY) singe crystal several successive technologies: laser synthesis of NDY nanopowder, pulsed magnetic compacting of the powder and two stage vacuum sintering were used. With the help of abnormal grain growth samples of NDY single crystal were produced. Conditions that are necessary for abnormal grain growth in Yttrium Oxide as well to grow the optical grade single crystal are discussed.
Hossam Sayour - One of the best experts on this subject based on the ideXlab platform.
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Biocompatibility and biodistribution of surface-modified Yttrium Oxide nanoparticles for potential theranostic applications
Environmental Science and Pollution Research, 2019Co-Authors: Hossam Sayour, Samr Kassem, Joanna Czulak, Medhat Mohamed, Francesco Canfarotta, Sergey PiletskyAbstract:The surface of ultrafine Yttrium Oxide nanoparticles (NPs) with mean size of 7–8 nm was modified with a functional polymer layer to improve their dispersion and impart fluorescent properties for imaging purposes. Surface functionalization was achieved by silanization of Yttrium Oxide NPs with 3-trimethoxysilylpropyl methacrylate followed by grafting of a co-polymer made of acrylic acid (AA) and ethylene glycol methacrylate phosphate (EGMP). The polymer shell decreases the surface energy of NPs, enhances their polarity, and, as a result, improves their colloidal stability. The synthesized NPs are capable of scavenging free radicals and for this reason have therapeutic potential that warrants further investigations. Furthermore, these stabilized core–shell NPs showed a very low cytotoxicity, confirming that the polymer shell sensibly improves the biocompatibility of bare Yttrium Oxide NPs, which are otherwise toxic on their own. Poly-EGMP Yttrium NPs proved to be safe up to 0.1 mg/g body weight in 1 month old Sprague–Dawley rats, showing also the ability to cross the blood–brain barrier short time after tail injection. The surface modification of Yttrium NPs here described allows these NPs to be potentially used in theranostics to reduce neurodegenerative damage due to the heat stress.
Johanne Mouzon - One of the best experts on this subject based on the ideXlab platform.
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Alternative method to precipitation techniques for synthesizing Yttrium Oxide nanopowder
Powder Technology, 2007Co-Authors: Johanne Mouzon, Magnus OdénAbstract:Yttrium Oxide nano-powder has been successfully synthesized by a novel approach. In the first step, a foamy structure was produced by combustion synthesis using Yttrium nitrate and glycine. This wa ...
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Synthesis of ytterbium-doped Yttrium Oxide nanoparticles and transparent ceramics
2006Co-Authors: Johanne MouzonAbstract:In this thesis, the author reports on a ceramic process leading to transparent ytterbium doped Yttrium Oxide ceramics. The full production route was investigated, namely: powder preparation, compaction and sintering. First, yttria nano-powder was fabricated from a precursor with transient morphology, i.e. Yttrium hydroxynitrate platelets that decomposed into spherical yttria nano-particles during calcination. The influence of different dewatering methods on such precursors was investigated. Water removal by freeze-drying was shown to be optimal for the production of non- agglomerated nano-particles compared to other methods that involve solvent removal by evaporation. This was attributed to the ability of freeze-drying to avoid the formation of solid bridges, since water is directly removed by sublimation. In a second step, doping with ytterbium was performed. Two precipitation routes were compared: precipitation of hydroxynitrate platelets and precipitation of amorphous carbonate. The latter route was shown to allow a better distribution of ytterbium in the Yttrium Oxide matrix after calcination of the corresponding precursor. This was attributed to good cation mixing within the amorphous particles, while formation of the hydroxynitrate platelets resulted in segregation of ytterbium because of the precipitation of an ytterbium-rich secondary phase. Because of the laborious character of the above techniques, an alternative method for synthesizing Yttrium Oxide powder was developed. This method not only allows for producing weakly-agglomerated nano-particles with equiaxed morphology, but is also a very time-efficient process. Its characteristic feature lies in the ability to skip two processing steps encountered in common precipitation techniques (i.e. filtration and drying). The method is based on combustion synthesis, sulfation, and calcination at high temperature. Through careful tailoring of the process parameters, evolution of the cellular nanostructure towards individual Yttrium Oxide nano- particles was obtained during firing. A method combining pre-sintering in vacuum followed by hot isostatic pressing (HIP) using glass encapsulation was shown to be successful to produce transparent yttria ceramics from agglomerated powders. Pre- sintering in vacuum of compact agglomerates enables differential sintering, resulting in only intergranular porosity. Subsequent HIP treatment of the pre-sintered samples caused almost complete pore elimination and achievement of transparency. However, macro-defects were present in the final material. From these results it became obvious that the packing homogeneity must be improved. For comparison, green-bodies were produced by slip-casting or pressing followed by cold isostatic pressing (CIP). Rheology studies were performed in order to tailor the milling conditions and the quantity of dispersant to obtain slurries with minimum viscosity and which were suitable for slip-casting. Although slip-cast pellets exhibited similar densities as pressed samples after pre-sintering, they showed more homogeneous optical properties after HIP. This was attributed to density gradients in the pressed compacts. By using the novel powder synthesis and HIP methods developed in this work, Yttrium Oxide transparent ceramics doped with 30 at% ytterbium were fabricated. The best sample showed a transmittance of 25% at 400 nm for a thickness of 3mm.
