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Debarros F.,Grenoble Institute of Technology | Lemaitre-Auger P.,Grenoble Institute of Technology | De Menezes A.V.G.,Grenoble Institute of Technology | Siragusa R.,Grenoble Institute of Technology | And 3 more authors.
International Journal of Microwave and Wireless Technologies | Year: 2012

The possibility to characterize infinite and periodic frequency-selective surfaces (FSS) filters that have two orthogonal axes of symmetry inside a waveguide is reported. Thus, preliminary measurements can rapidly be obtained at low cost with few elementary cells instead of using a large FSS panel in free space. This is possible because of the equivalence that exists between the electromagnetic fields of two symmetric and oblique plane waves incident on and reflected from an infinite periodic surface and the incident/reflected fields that exist inside a single-mode rectangular waveguide containing a finite number of elementary cells. Comparisons of the measurements with some full-wave simulations for FSS belonging to the first three groups as they were defined by Munk confirm the good agreement between them. This is an interesting and simple assessment tool concerning the fabrication quality of FSS. The extension of this technique to non-symmetric FSS patterns is also discussed and supported by experimental and simulation results. The limitations of the technique are finally discussed. © Copyright Cambridge University Press and the European Microwave Association 2011. Source

Napierala C.,LEMA | Napierala C.,Directorate General of Armaments | Lepoittevin C.,University of Antwerp | Edely M.,LPEC | And 4 more authors.
Journal of Solid State Chemistry | Year: 2010

Rare earth nickelates exhibit a reversible metal-semiconductor phase transition that is, in the infrared range, responsible for a thermo-optical contrast. The state of the art synthesis of these compounds usually requires high oxygen pressure to stabilize Ni in the oxidation state 3+. In this work, using polymeric precursor associated with moderate pressure annealing, we show that it is possible to obtain fully oxidized rare earth nickelate with metal-insulator transition. Using thermogravimetric analysis, X-ray diffraction and transmission electronic microscopy we compare different samples synthesized at different oxygen pressures and demonstrate their structural similarity. Thermo-optical properties were measured, in the infrared range, using reflectance measurements and confirmed the metal-insulator transition at 60 °C in both samples.TEM observations lead to the conclusion that the structure commonly obtained at 175 bar is perfectly observed in the 20 bar sample without major structural defects. The two samples exhibit a thermochromic behavior and thermo-optical properties of the two samples are equivalent. © 2010 Elsevier Inc. All rights reserved. Source

Hinfray N.,INERIS | Palluel O.,INERIS | Piccini B.,INERIS | Sanchez W.,INERIS | And 7 more authors.
Science of the Total Environment | Year: 2010

The aim of this study was to assess endocrine disruptive effects in wild population of fish in five French rivers selected to represent different pollution contexts at two seasons (summer and fall). For that purpose, a panel of biometrical parameters (length, weight, and gonado-somatic index: GSI) and biochemical (ethoxyresorufin-O-deethylase: EROD, vitellogenin: VTG, and brain aromatase) and histological biomarkers (gonads histology) were used in chub (Leuciscus cephalus), a common cyprinid fish species. In fish from the reference site, EROD activity and VTG levels were low at the two seasons. Brain aromatase activities (AAs) were similar to other species and increased with increasing GSI and gonad maturation. Among the four contaminated sites, the Jalle d'Eysines River was the most impacted site. At this site, fish were exposed to estrogenic substances as demonstrated by the VTG induction in males and the arrest of development of the gonads that led to lower brain AA compared to fish from the reference site. In fish from other contaminated sites, EROD activity was induced as compared to fish from the reference site and some males had elevated concentrations of VTG. Moreover, the presence of aromatase-inhibiting compounds was demonstrated in the sediments of three contaminated sites, even if the precise nature of contaminants is not known. This study provides new data concerning endocrine disruption in wild fish populations inhabiting French rivers and demonstrates that measurements of in vivo and in vitro aromatase could be used as biomarkers of endocrine disruption in field studies. © 2009 Elsevier B.V. All rights reserved. Source

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