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Drémil-Lafage, France

Osseni S.A.,University Of Toulouse Ups | Lechevallier S.,University Of Toulouse Ups | Verelst M.,University Of Toulouse Ups | Verelst M.,PYLOTE SA | And 8 more authors.
Journal of Materials Chemistry

The synthesis of Gd2O2S:Eu3+ nanoparticles (NPs), from hydroxycarbonate precursor precipitation followed by sulfuration in a H2S/Ar atmosphere at 750 °C; is reported. It is the first time that the size of Gd2O2S:Eu3+ NPs can be finely tuned from 60 nm to more than 200 nm by controlling the precipitation medium, the maturation time and the sulfuration route. The oxysulfide Gd 2O2S:Eu3+ NPs emit strong red luminescence at 624 nm when excited by near UV (363 nm) or by X-rays. They may thus be considered as nano-phosphors and nano-scintillators. Then, the surface of oxysulfide NPs has been modified by an amino-silica or by a mesoporous silica shell (thickness 10-15 nm). The luminescence intensity of europium in gadolinium oxysulfide NPs has been maintained in the amino-silica coated particles Gd 2O2S:Eu3+@SiO2-APTMS, whereas it has been significantly enhanced in the mesoporous silica coated Gd 2O2S:Eu3+@mSiO2. This versatile new nanoplatform can be easily internalized in living NIH3T3 mouse cells. It is not cytotoxic up to 1 mg mL-1 and can be easily imaged by epifluorescence microscopy with excitation in the NUV. Consequently this spherical monodispersed Gd2O2S:Eu3+ nanophosphor could be considered as a very promising new fluorescent probe for bio-labelling, better than the corresponding oxide or fluoride nanoparticles. © 2011 The Royal Society of Chemistry. Source

Azizi Y.,University Claude Bernard Lyon 1 | Kambolis A.,University Claude Bernard Lyon 1 | Boreave A.,University Claude Bernard Lyon 1 | Giroir-Fendler A.,University Claude Bernard Lyon 1 | And 4 more authors.
Surface Science

A series of Ag catalysts supported on γ-Al2O3, including two different γ-Al2O3 supports and various Ag loadings (2-8 wt.%), was prepared, characterized (SEM, TEM, BET, physisorption, TPR, NH3-TPD) and tested for the selective catalytic reduction of NOx by CH4 for lean-burn natural gas engines exhausts. The catalysts containing 2 wt.% Ag supported on γ-Al2O3 were found to be most efficient for the NOx reduction into N2 with a maximal conversion of 23% at 650 °C. This activity was clearly linked with the ability of the catalyst to concomitantly produce CO, via the methane steam reforming, and NO2. The presence of small AgOx nanoparticles seems to be crucial for the methane activation and NOx reduction. © 2015 Elsevier B.V. All rights reserved. Source

Silvestre C.,CNR Institute of Chemistry and Technology of Polymers | Cimmino S.,CNR Institute of Chemistry and Technology of Polymers | Pezzuto M.,CNR Institute of Chemistry and Technology of Polymers | Marra A.,University of Naples Federico II | And 6 more authors.
Polymer Journal

In this study, we investigated the influence of ZnO particles obtained by spray pyrolysis with submicron dimensions on the structure, morphology, thermal stability, photodegradation stability, mechanical and antibacterial properties of isotactic polypropylene (iPP)/ZnO composites prepared by melt mixing. The results of the morphological analyses indicate that, despite the surface polarity mismatch between iPP and ZnO, the extrusion process and the unique characteristics of the utilized particles allow a composite with a fair distribution of particles to be obtained, although some agglomeration phenomena can occur, which primarily depends on the composition of the composite. The addition of ZnO particles imparts significant improvements on the photodegradation resistance of iPP to ultraviolet irradiation, which confirms that ZnO particles act as screens for this type of radiation. The thermal stability of the iPP/ZnO composites is improved with respect to that of neat iPP and increases with the content of ZnO. The iPP/ZnO composites exhibit significant antibacterial activity against Escherichia coli. This activity is dependent on exposure time and composition. © 2013 The Society of Polymer Science, Japan (SPSJ) All rights reserved. Source

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