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Chetumal, Mexico

The University of Quintana Roo is a Mexican public university with several campuses across the state of Quintana Roo, in the Yucatán peninsula. It was created on 24 May 1991.Its library system holds over 36,634 volumes. Wikipedia.

Delgado-Blas V.H.,University of Quintana Roo | Salazar-Silva P.,Colegio de Mexico

The aim of this study was to provide a revised taxonomic catalogue of Spionidae species recorded from the Grand Caribbean. The names included were compiled from the checklists of Salazar-Vallejo (1996) and Perkins and Savage (1975). Names were revised and updated based on recent revisions. For each species, the original name is included together with current and previous names under which it has been recorded; all with associated citations. The type locality of each species, museum or institution where the type materials are deposited, and comments on systematics and geographic distributions are also included. The catalogue lists 66 species in 24 genera and at the end a list of species with questionable distribution in the Grand Caribbean is included. © 2011 . Magnolia Press. Source

Available type material of Prionospio heterobranchia Moore, 1907, P. (Prionospio) texana Hartman, 1951, P. spongicola Wesenberg-Lund, 1958 and P. (P.) newportensis Reish, 1959, as well as newly collected material from the Southern Gulf of Mexico and Chetumal Bay in the Caribbean Sea, was examined. Several important differences were found between P. heterobranchia, P. (Prionospio) texana, P. spongicola and P. (P.) newportensis, and as a result, these three species are removed from synonymy with P. heterobranchia Moore, 1907, and redescribed and reinstated as valid species. In addition, three new species were identified and described: P. caribensis sp. nov., P. rosariae sp. nov. and P. jamaicensis sp. nov. A key to all species of Prionospio with five pairs of branchiae is provided. © 2013 Springer-Verlag Berlin Heidelberg and AWI. Source

Escobar B.,Technological Institute of Cancun | Barbosa R.,University of Quintana Roo | Miki Yoshida M.,CIMAV | Verde Gomez Y.,Technological Institute of Cancun
Journal of Power Sources

Pt colloidal nanoparticles were synthesized by simultaneous chemical reduction of metallic salts in presence of poly (N-vinyl-2-pyrrolidone) as protecting agent. The uniform and highly ordered Pt colloidal nanoparticles were associated to well dispersed particles ranging in particle size distribution around 4.5 ± 1.9 nm. The nanoparticles were deposited onto multiwalled carbon nanotubes (MWCNT). MWCNT were synthesized by chemical vapor deposition (CVD) method. Before the metal impregnation, the MWCNT were treated with HNO3 in reflux. Prepared Pt catalyst were characterized by various physical and electrochemical techniques, that is, X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and cyclic voltammetry (CV). Raman spectroscopy reveals changes intensity ratio IG′/IG in the samples, after the cleaning process and Pt loading, indicating changes in the crystallinity of the materials. HRTEM showed Pt particles between 6.1 ± 0.9 nm and 6.5 ± 1.5 nm are well dispersed along the carbon nanotubes. XRD patterns show characteristics peaks corresponding to graphite and metallic Pt. The electrochemical properties of the MWCNT supported Pt nanoparticles were investigated by analyzing the response of the nanostructured catalyst for cyclic voltammetry and compared with a commercial material. © 2013 Elsevier B.V. All rights reserved. Source

De Leon-Aldaco S.E.,National center for research and development of technology | Calleja H.,National center for research and development of technology | Chan F.,University of Quintana Roo | Jimenez-Grajales H.R.,Electric Research Institute of Mexico
IEEE Transactions on Power Electronics

This paper presents the reliability analysis of a push-pull converter intended for connection to a 125-W photovoltaic (PV) panel. Four prototypes of the converter were built and tested, using transistors with different ratings. Failure rates were calculated using theMIL HDBK 217 and the IEC TR 62380 procedures. In the latter case, the predictionwas performed taking into account an annual mission profile obtained from the intended installation site, in an area with desert climate temperatures. Failure rate results obtained withMIL HDBK 217 show small differences among the converters, the best performance obtained from the prototype with the lowest on-resistance. Results obtained with IEC TR 62380 indicate that thermal cycles have a significant effect in reliability performance, and should be considered carefully, because PV systems often see large temperature variations.With both procedures, the failure rate contributions from magnetic devices were higher than expected. © 2013 IEEE. Source

Aguilar J.O.,Research Center Cientifica Of Yucatan | Aguilar J.O.,University of Quintana Roo | Bautista-Quijano J.R.,Research Center Cientifica Of Yucatan | Aviles F.,Research Center Cientifica Of Yucatan
Express Polymer Letters

Electrical conductivity of 150-200 μm thick polysulfone films loaded with 0.05-0.75% w/w multiwall carbon nanotubes was systematically investigated for two types of dispersion states, uniformly dispersed and agglomerated at the micro-scale. The percolation threshold was found at 0.11% and 0.068% w/w for the uniformly dispersed and agglomerated films, respectively. Overall, the conductivity of the films with agglomerated nanotubes was higher than that of the uniformly dispersed ones, with marked differences of 2 to 4 orders of magnitude for carbon nanotubes loadings in the upper vicinity of the percolation threshold (0.1-0.3% w/w). The increased conductivity of the agglomerated state is explained by the increased nanotube-to-nanotube contact after the percolating network has formed, which facilitates electron transfer. © BME-PT. Source

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