Caractérisation de matériaux diélectriques anisotropes

International audienceDe nos jours, le fonctionnement de la grande majorité des convertisseurs hertzien/optique repose sur les propriétés électrooptiques d'un matériau anisotrope cristallin, le niobate de lithium. Lorsqu'une onde optique pénètre dans le matériau, sa vitesse de propagation varie en fonction de l'intensité du champ électrique appliqué suivant l'effet Pockels (variation d'indice dépendante de l'intensité de champ). En général, cette variation est transformée en modulation d'intensité dans un interféromètre de type Mach-Zender ou à l'aide de polariseurs qui transforment la rotation de la polarisation en une variation d'intensité. La principale différence entre les deux méthodes est que dans le premier cas la structure de modulation est planaire, et qu'elle est volumique dans l'autre cas. Bien que déjà très répandu, le niobate de lithium a plusieurs inconvénients non négligeables : son coût de fabrication est très élevé, son coefficient électrooptique est faible et sa constante diélectrique haute fréquence est élevée. Pour pallier ces inconvénients, des matériaux à base de polymères sont actuellement développés. Nous nous intéressons à la caractérisation et à l'utilisation de ce type de matériaux. Dans cet article, nous présentons la méthode de mesure mise en œuvre pour déterminer la partie réelle de la constante diélectrique de ces matériaux en tenant compte de l'anisotropie

Passive electro-optic antenna using polymer material

International audienceThe experimental results of a polymer microwave electro-optic antenna are reported. The device amplitude-modulates an optical input beam with a free-space propagating electromagnetic wave. By using a new dipole printed antenna, the electromagnetic energy is concentrated inside the device. An antenna factor of 168 dB/m is achieved with only 1 mum of electro-optic polyme

Electrooptic microwave antenna using organic poled polymers

International audienceWe propose a new electrooptic antenna design using organic polymer to receive microwave signals. In this paper we present the characterization of an electrooptic organic polymer. We measured the dielectric constant at microwave frequencies, and the electrooptic coefficient. We measured values of r33 of 3.35 pm/V at 1310 nm and 1.98 pm/V at 1550 nm. The goal of the electrooptic antenna design is to obtain maximum microwave and optical interaction. We propose a novel approach based on resonance effect in both optical and microwave domain. For the optical resonance effect we use a Fabry-Perot cavity, and a patch structure as microwave resonator

Characterization of electrooptic polymer applied to microwave sensing

International audienceIn this paper we present electrooptic measurement of a crosslinked side chain PGMA/DR1 polymer. Measured values are as high as 11 pm/V at 1310 nm, we present measurement as a function of incident beam reflexion point and show dependance between the reflexion point location over the sample and the measured electrooptic coefficient. We present low frequency relative dielectric constant using a capacitance measurement method. Using this method, we found a relative permittivity of 4.46plusmn0.38 for our polymer. We present a new electrooptic microwave sensor, where we enhance the electrooptical interaction by increasing the optical path length using a Fabry-Perot cavity and we concentrate the electric field inside our device using a microstrip resonator. Expected interaction enhancement value is expected to be as high 310deg compared to the simple reflexion case at low frequenc

Elaboración de sondas moleculares para la detección de virus de yerba mate

La yerba mate (Ilex paraguariensis A St‐Hil) es un arbusto perenne originario de América del Sur. En Argentina, se evidenciaron plantas de yerba mate con síntomas virales de amarillamiento, clorosis de nervaduras, moteado, anillos y diseños lineales cloróticos. Análisis mediante microscopía electrónica, técnicas moleculares y secuenciación masiva, permitieron identificar los virus Yerba mate chlorosis-associated virus (YmCaV), perteneciente al género Cytorhabdovirus, Yerba mate-associated circular DNA virus (YMaCV), un virus circular de ADN monocatenario, y otro patógeno viral parcialmente secuenciado, posiblemente de la familia Closteroviridae. El objetivo del trabajo fue elaborar sondas moleculares para la identificación masiva de los virus de yerba mate. Se purificaron productos de PCR amplificados con cebadores específicos, diseñados para cada uno de los virus. Los productos aislados se clonaron y secuenciaron para confirmar la identidad del inserto. A partir de los plásmidos seleccionados se sintetizaron ribosondas para la detección de YmCaV y el posible closterovirus, y una sonda de DNA para el virus YMaCV, utilizando los kits ?RNA Labeling and Detection? y ?DIG DNA Labeling and Detection? (Roche), respectivamente. Para el diagnóstico de plantas de yerba mate, se ajustó la técnica dot blot en nitrocelulosa. Las sondas específicas para YmCaV y YMaCV reaccionaron con los testigos positivos de cada virus, mientras que no reaccionaron con los testigos negativos. La sonda para la detección del posible closterovirus sigue en desarrollo. Este trabajo permitió ajustar una técnica para el diagnóstico masivo de los virus YmCaV y YMaCV.Fil: Nome, Claudia. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Fitopatología y Modelización Agrícola - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Fitopatología y Modelización Agrícola; ArgentinaFil: Bejerman, Nicolas. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Fitopatología y Modelización Agrícola - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Fitopatología y Modelización Agrícola; ArgentinaFil: de Breuil, Soledad. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Fitopatología y Modelización Agrícola - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Fitopatología y Modelización Agrícola; Argentina5to Congreso Argentino de Fitopatología y 59º Reunión APS División CaribeArgentinaAsociación Argentina de Fitopatólogo

Genomic Characterization of the Taylorella Genus

The Taylorella genus comprises two species: Taylorella equigenitalis, which causes contagious equine metritis, and Taylorella asinigenitalis, a closely-related species mainly found in donkeys. We herein report on the first genome sequence of T. asinigenitalis, analyzing and comparing it with the recently-sequenced T. equigenitalis genome. The T. asinigenitalis genome contains a single circular chromosome of 1,638,559 bp with a 38.3% GC content and 1,534 coding sequences (CDS). While 212 CDSs were T. asinigenitalis-specific, 1,322 had orthologs in T. equigenitalis. Two hundred and thirty-four T. equigenitalis CDSs had no orthologs in T. asinigenitalis. Analysis of the basic nutrition metabolism of both Taylorella species showed that malate, glutamate and alpha-ketoglutarate may be their main carbon and energy sources. For both species, we identified four different secretion systems and several proteins potentially involved in binding and colonization of host cells, suggesting a strong potential for interaction with their host. T. equigenitalis seems better-equipped than T. asinigenitalis in terms of virulence since we identified numerous proteins potentially involved in pathogenicity, including hemagluttinin-related proteins, a type IV secretion system, TonB-dependent lactoferrin and transferrin receptors, and YadA and Hep_Hag domains containing proteins. This is the first molecular characterization of Taylorella genus members, and the first molecular identification of factors potentially involved in T. asinigenitalis and T. equigenitalis pathogenicity and host colonization. This study facilitates a genetic understanding of growth phenotypes, animal host preference and pathogenic capacity, paving the way for future functional investigations into this largely unknown genus

Trap emtying time in LT CdTe Films determined by Time Resolved Reflectance near Brewster’s Angle

International audienc

Identification and molecular characterization of a novel circularsingle?stranded DNA virus associated with yerba mate in Argentina

AbstractA single-stranded DNA (ssDNA) virus was detected in Yerba mate samples showing chlorotic linear patterns, chloroticrings and vein yellowing. The full-genome sequences of six different isolates of this ssDNA circular virus were obtained,which share > 99% sequence identity with each other. The newly identified virus has been tentatively named as yerbamate-associated circular DNA virus (YMaCV). The 2707 nt-long viral genome has two and three open reading frame onits complementary and virion-sense strands, respectively. The coat protein is more similar to that of mastreviruses (44%identity), whereas the replication-associated protein of YMaCV is more similar (49% identity) to that encoded by a recentlydescribed, unclassified ssDNA virus isolated on trees in Brazil. This is the first report of a circular DNA virus associatedwith yerba mate. Its unique genome organization and phylogenetic relationships indicates that YMaCV represents a distinctevolutionary lineage within the ssDNA viruses and therefore this virus should be classified as a member of a new specieswithin an unassigned genus or family

Molecular characterization of Sunflower chlorotic mottle virus: A member of a distinct species in the genus Potyvirus

The complete nucleotide (nt) and deduced amino acid (aa) sequences of the C (common) and CRS (chlorotic ringspot) Argentine strains of SuCMoV have been determined. The SuCMoV-C RNA genome consists of 9,965 nt, whereas indels within the P1 coding region of SuCMoV-CRS make its genomic length 15 nt shorter. Nucleotide and aa sequence identities between the polyproteins of the C and CRS strains of SuCMoV were 92.3 and 95.6%, respectively. Pairwise comparisons between the polyproteins of the C and CRS strains of SuCMoV and the viruses of the Potato virus Y (PVY) subgroup revealed identities of 66.5-66.9% at the nt level and 69.7-69. 8% at the aa level. These results and phylogenetic analyses show that although SuCMoV strains cluster together with the potyviruses belonging to the PVY subgroup, SuCMoV should be considered a member of a distinct species in the genus Potyvirus. © 2010 Springer-Verlag.Fil: Bejerman, Nicolas. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Fitopatología y Fisiología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Giolitti, Fabián José. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Fitopatología y Fisiología Vegetal; ArgentinaFil: de Breuil, Soledad. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Fitopatología y Fisiología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Lenardon, Sergio Luis. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Fitopatología y Fisiología Vegetal; Argentina. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; Argentin