Crystallization of microscopic Y2O3 powders by different techniques of fluidization at high temperature

Ahigh temperature fluidized bed reactor (HTFBR)working at 900 to 1200 ◦Chas been developed to crystallize microscopic yttria (Y2O3) powders synthesized by spray pyrolysis. Such crystallization is classically performed in crucible or in moving belt furnaces. In order to demonstrate the advantages of the fluidized bed process over the conventional static mode treatments, a comparative study of the main characteristics of particles after heat treatment in a crucible and in the HTFBR has been performed. The high interparticle forces existing in such Geldart group C powders made it necessary to activate their fluidization. Following previous results, two activated fluidization processes were studied: addition of coarse powders to fine particles and vibrated fluidization. The hydrodynamic behavior of these fluidized beds was analyzed through pressure drop measurements. Convenient fluidization conditions were obtained for the two activated fluidization processes, leading to isothermal beds. The size distribution, the crystallinity and the outer morphology of particles before and after thermal treatments were analyzed and compared for the three processes tested. Some pre-sintering phenomena occurred at 1200 ◦C, which were clearly more intense in crucible than in activated fluidization. The crystallinity of the samples treated was equivalent for the three methods of thermal treatment. The interest of fluidization processes to post-treat microscopic particles is thus fully demonstrated

Y2O3:Eu micronic particles synthesised by spray pyrolysis: Global modelling and optimisation of the evaporation stage

There are a number of some major advantages to be gained in processing micronic europium-doped yttrium oxide Y2O3 particles for phosphor applications using spray pyrolysis. In order to maximise production rates, it is tempting to use relatively dense sprays, but then coalescence occurs increasing final particle diameters, which must be prevented. Moreover, the influence of the operating conditions on the process behaviour is poorly understood. A complete one-dimensional model of the evaporation stage of micronic water/Y(NO3)3 droplets considering only the evaporation process and then both evaporation and gravity-induced coalescence phenomena has been established. Calculations of pure evaporation have shown that the amounts of evaporated water and droplet compositions depend only on the local temperature and not on the thermal history of the spray. Coupled calculations have shown that, in comparison with evaporation, coalescence plays a minor role on droplet diameter, but non-negligible as the increase of the final mean droplet diameter due to coalescence reaches up to 10% at low flow rates in the operating conditions tested. Injecting a preheated air flow directly into the nebuliser is a promising method to minimise coalescence effects: optimal operating conditions for which coalescence is completely insignificant were obtained by simulation

Electro-precipitation of magnetite nanoparticles: an electrochemical study

Nanoparticles of magnetites (Fe3O4) are synthesized with a new process based on electro-precipitation in ethanol medium. A mechanism pathway is proposed consisting of a Fe(OH)3 precipitation followed by the reduction of iron hydroxide to magnetite in the presence of hydroxyl ions which are enerated at the cathode

Antimicrobial activity of metal oxide microspheres: an innovative process for homogeneous incorporation into materials

AIMS:To investigate the potent control of microbial surface contamination of an innovative process which consists in incorporating metal oxide microspheres homogeneously into materials. Spherical microspheres containing zinc and magnesium oxides synthesized via a one-step manufacturing process (Pyrolyse Pulvérisée® ) and incorporated into different plastic matrices were evaluated for their antimicrobial activity according to JIS Z 2801 standard. A significant activity was observed for microsphere-added polyethylene coupons with a reduction of all tested bacteria populations, including Gram negative and Gram positive even expressing acquired antibiotic resistance (Escherichia coli ESBL, Staphylococcus aureus metiR). An antiviral activity higher than 2 log of reduction was also observed on H1N1 and HSV-1 viruses. This antimicrobial effect was dose-dependent and time-dependent for both polyethylene and polypropylene matrices. Antimicrobial activity was maintained after exposition to disinfectants and totally preserved 50 months after the preparation of the coupons. CONCLUSIONS:Incorporated into plastic matrices, metal oxide microspheres showed significant antibacterial and antiviral activities. SIGNIFICANCE AND IMPACT OF STUDY: This is, to our knowledge, the first report on an original process incorporating metal oxide microspheres, which have specific physico-chemical and antimicrobial properties, into materials that could be used for surface contamination prevention

Schéma de Développement Territorial de la Grande Région - CAHIER THEMATIQUE N°1 : Dynamiques démographiques et les besoins territoriaux associés

Die Aktion 3 des Interreg-Projektes REK GR mit dem Namen « Eine gemeinsam genutzte Wissensbasis und eine gemeinsame Sprache entwickeln » zielt darauf ab, das Gebiet der Großregion aus Sicht mehrerer Themen zu beleuchten. Vier Themen wurden festgehalten und werden jeweils in einem spezifischen Heft ausgearbeitet. Ein fünftes Heft fasst die beiden Workshops zusammen, an denen alle Schlüsselakteure der Großregion beteiligt waren, um die sektoriellen und bereichsübergreifenden Herausforderungen der künftigen territorialen Entwicklung zu bestimmen (Risiken und Chancen). - Themenheft Nr. 1: Demographische Dynamik und damit verbundene räumliche Erfordernisse - Themenheft Nr. 2: Mobilität von Personen und Gütern - Themenheft Nr. 3: Wirtschaftliche Entwicklung - Themenheft Nr. 4: Umwelt – Energie - Zusammenfassendes Heft Nr. 5: Herausforderungen der territorialen Entwicklung der GroßregionSDTG

Luminescence Properties of Mesoporous Silica Nanoparticles Encapsulating Different Europium Complexes: Application for Biolabelling

In this work we have synthesized and characterized new hybrid nanoplatforms for luminescent biolabeling based on the concept of Eu3+ complexes encapsulation in mesoporous silica nanoparticles (≈100 nm). Eu complexes have been selected on the basis of their capability to be excited at 365 nm which is a currently available wavelength, on routine epifluorescence microscope. For Eu complexes encapsulation, two different routes have been used: the first route consists in grafting the transition metal complex into the silica wall surface. The second way deals with impregnation of the mesoporous silica NPs with the Eu complex. Using the second route, a silica shell coating is realized, to prevent any dye release, and the best result has been obtained using Eu-BHHCT complex. However, the best solution appears to be the grafting of Eu(TTA)3-Phen-Si to mesoporous silica NPs. For this hybrid, mSiO2-Eu(TTA)3(Phen-Si) full characterization of the nanoplatforms is also presented

Elaboration et caracterisation de composites a matrice metallique Ni/Al_2O_3 et Ni/Cr_2O_3 par codeposition electrochimique. Application a l'electroformage de spheres creuses

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 79434 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Radioiodine therapy in voluminous multinodular non-toxic goitre

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Synthèse et caractérisation de nanoparticules métalliques (application à l'élaboration de nanocomposites)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF