Thermal profiles within the channel of planar gunn diodes using micro-particle sensors

The paper describes the use of a novel microparticle sensor (~3 μm diameter) and infra-red (IR) microscopy to measure the temperature profile within the active channel (typically 3 μm length and 120 μm width) of planar Gunn diodes. The method has enabled detailed temperature measurements showing an asymmetrical temperature profile along the active width of these devices. The asymmetrical temperature profile suggests a similar behaviour in the channel current density, which may contribute to the lower than expected RF output power

Impact ionisation electroluminescence in planar GaAs-based heterostructure Gunn diodes:Spatial distribution and impact of doping nonuniformities

When biased in the negative differential resistance regime, electroluminescence (EL) is emitted from planar GaAs heterostructure Gunn diodes. This EL is due to the recombination of electrons in the device channel with holes that are generated by impact ionisation when the Gunn domains reach the anode edge. The EL forms non-uniform patterns whose intensity shows short-range intensity variations in the direction parallel to the contacts and decreases along the device channel towards the cathode. This paper employs Monte Carlo models, in conjunction with the experimental data, to analyse these non-uniform EL patterns and to study the carrier dynamics responsible for them. It is found that the short-range lateral (i.e., parallel to the device contacts) EL patterns are probably due to non-uniformities in the doping of the anode contact, illustrating the usefulness of EL analysis on the detection of such inhomogeneities. The overall decreasing EL intensity towards the anode is also discussed in terms of the interaction of holes with the time-dependent electric field due to the transit of the Gunn domains. Due to their lower relative mobility and the low electric field outside of the Gunn domain, freshly generated holes remain close to the anode until the arrival of a new domain accelerates them towards the cathode. When the average over the transit of several Gunn domains is considered, this results in a higher hole density, and hence a higher EL intensity, next to the anode

Primer registro de Diphterostomum brusinae (Digenea, Zoogonidae) parasitando a la corvina Micropogonias furnieri con datos sobre su ciclo biológico

En un estudio que ampliará el conocimiento de los parásitos de peces de ambientes mixohalinos de Argentina, se hallaron ejemplares adultos de Diphterostomum brusinae parasitando el intestino de juveniles de la corvina, Micropogonias furnieri (Sciaenidae), en el estuario de Bahía Blanca (N = 142) y en la Bahía de Samborombón (N = 265) (provincia de Buenos Aires). Los valores de prevalencia (P) e intensidad media (IM) fueron mayores en el primer sitio (P = 18,3% vs 14,7%; IM = 18,9 vs 6,7). La morfología y las medidas de los especímenes concuerdan con aquellos brindados en la descripción original de D. brusinae. Los adultos se caracterizaron por poseer un tegumento espinoso, dos ciegos intestinales saculares y un acetábulo bien desarrollado con dos pares de labios musculares (uno anterior y otro posterior). En la Bahía de Samborombón también se hallaron estadios larvales (esporocistos, cercarias y metacercarias) parasitando al caracol Buccinanops globulosus (Nassariidae). La morfología y medidas de estos estadios también fueron coincidentes con los descritos anteriormente para D. brusinae. En este trabajo se reporta por primera vez D. brusinae en M. furnieri de Argentina y se propone parte del desarrollo de su ciclo de vida en la Bahía de Samborombón, Argentina.In a survey to increase the knowledge about parasites of fishes in brackish waters of Argentina, we found adult specimens of Diphterostomum brusinae parasitizing the gut of juveniles of the whitemouth croaker, Micropogonias furnieri (Sciaenidae), in Bahía Blanca estuary (N=142) and in Samborombón Bay (N=265) (Buenos Aires Province, Argentina). Prevalence (P) and mean intensity (MI) were higher in the first site (P = 18,3 % vs. 14,7 %; MI = 18,9 vs. 6,7). Measurements and morphology of specimens fits with the description previously made for D. brusinae. Adults typically have a densely spiny tegument, two small and sacular intestinal caeca, and a well-developed ventral sucker with two pairs of muscular lips. In Samborombón Bay we also found larval stages (sporocysts, cercariae, and metacercariae) parasitizing the intertidal snail Buccinanops globulosus (Nassariidae). The morphology and measurements are also coincident to those described for larvae stages of D. brusinae. In this work we record for the first time D. brusinae in M. furnieri from Argentina and partially propose the life cycle of this species in Samborombón Bay, Argentina.Fil: Martorelli, Sergio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores (i); ArgentinaFil: Montes, Martin Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores (i); ArgentinaFil: Marcotegui, Paula Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores (i); ArgentinaFil: Alda, Maria del Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores (i); Argentin

Identification of two species of Binema Travassos, 1925 (Oxyurida: Travassosinematidae) and Cameronia arecoensis Marchissio and Miralles, 1987 (Oxyurida: Thelastomatidae) based on morphological and 18S rRNA partial sequence

Oxyurid nematodes parasitizing the mole cricket Neoscapteriscus vicinus were isolated in the framework of sampling fields of mole-crickets from the pampean region, in Argentina. In this work, molecular characterization of the 18S rRNA partial sequence of nematodes belonging to the families Thelastomatidae (Cameronia arecoensis Marchissio and Miralles 1987) and Travassosinematidae (Binema korsakowi Sergiev 1923 and Binema klossae, Marchissio and Miralles 1993) were carried out. This is the first world report of sequences belonging to B. klossae and C. arecoensis and first Argentinian report of B. korsakowi sequence. Also, morphological and morphometric features of B. klossae, B. korsakowi and C. arecoensis from Argentinian populations are reported.Fil: Rusconi, José Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Montes, Martin Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Ferrari, Walter Antonio Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Achinelly, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentin

Inflammatory reaction induced by Floridosentis mugilis (Acanthocephala, Neoechinorhynchidae) in the intestine of Mugil liza

Lebranche mullet, Mugil liza, is an important economic resource and has been recommended for aquaculture in South America. Also, this is the only mullet that breeds in Argentina. In the course of our routine investigations on the parasitic fauna of fishes from brackish waters of Samborombón Bay, Buenos Aires province, an infection of acanthocephalan worms, identified as Floridosentis mugilis was observed in juvenile lebranche mullets. These parasites were attached deeply into the intestinal wall but without piercing it. In this study we analysed the intestinal damage that F. mugilis inflicts on their hosts through the evaluation of histological sections. In the pathological analysis we observed that these parasites cause a non-specific cellular response that leads to the degranulation of eosinophilic granular cells and, consequently, the formation of a fibrous core with oedema, vascular congestion, and lymphocytic infiltration.Fil: Plaul, Silvia Elena. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Laboratorio de Histología y Embriología Descriptiva, Experimental y Comparada (LHYEDEC);Fil: Montes, Martin Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Topa, Pascual Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Martorelli, Sergio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Barbeito, Claudio Gustavo. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Laboratorio de Histología y Embriología Descriptiva, Experimental y Comparada (LHYEDEC); . Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The role of conductive additives on the performance of hybrid carbon xerogels as electrodes in aqueous supercapacitors

Three different hybrid carbon xerogels containing Graphene Oxide (AXGO), Micronized Graphite (AXMG) and Carbon Black (AXCB) were synthesized using an easy, fast and affordable method. These three additives were initially selected to improve the electrical conductivity of the pristine activated carbon xerogel (AX) thus expecting to improve its performance in aqueous supercapacitors. Capacitances of the corresponding devices were measured as a function of current density and results of the high and low charge transfer regime of the supercapacitors were discussed separately. In both regimes, the differences observed between the hybrid electrodes were analyzed on the basis of the concurrent influence of the micro and mesoporosity, surface chemistry and electrical conductivity of the materials. Accordingly, even though all the hybrid carbon xerogels showed higher electrical conductivities, only AXGO rendered a better performance than AX, showing the highest capacitances in the whole interval of intensities studied. Consequently, at 16 A g−1, the energy and power densities of the AXGO supercapacitors increased up to 16% and 97%, respectively, with respect to AX, and of 143% and 409%, respectively, with respect to a commercial activated carbon used as reference. The performance of AXCB and, especially AXMG was worse than AX supercapacitors due to a combination of inadequate pore size distributions and/or a poor surface chemistry. Finally, TEM analysis helped to understand the different way the three additives were affecting the nanostructure (and final properties) of the hybrid carbon xerogels.Authors gratefully acknowledge the financial support from the Ministerio de Economía, Industria y Competitividad from Spain (Project CTQ2017-87820-R). MCR also acknowledges CSIC (Project I.E. 201880E010)

Dermocystidiosis induced by the parasite Dermocystidium sp. in the Paracheirodon axelrodi

The Rio Negro floodplain (tributary of the Amazon River) is a natural habitat of the cardinal tetra Paracheirodon axelrodi. In home aquaria, this species has high vulnerability to superficial infetions and is affected by the protist Dermocystidium. Protist cysts were located in the dermis causing lesions reaching in the epidermis. We observed that a few weeks after the introduction of new wild ornamental fish (mostly Hemigrammus sp. or Hyphessobrycon sp.) into established home aquaria, the cardinal tetra fish became infected, suggesting that the new fish could have acted as carriers.Fil: Plaul, Silvia Elena. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Andres Laube, P. F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Montes, Martin Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Topa, Pascual Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Martorelli, Sergio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Barbeito, Claudio Gustavo. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentin