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Search Results: 1 - 10 of 231639 matches for " Ociel Rodríguez-Pérez "
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Nylon/Porphyrin/Graphene Oxide Fiber Ternary Composite, Synthesis and Characterization  [PDF]
César García-Pérez, Carmina Menchaca-Campos, Miguel A. García-Sánchez, Elsa Pereyra-Laguna, Ociel Rodríguez-Pérez, Jorge Uruchurtu-Chavarín
Open Journal of Composite Materials (OJCM) , 2017, DOI: 10.4236/ojcm.2017.73009
Abstract: This research was based on the manufacture of new composite materials that offer technological possibilities in the development of new devices with greater efficiency. Electrospinning was used to form nylon 66/-tetra-(para-aminophenyl) porphyrin (H2T(p-NH2)PP)/graphene oxide (GO) composite film. Graphene oxide coatings were obtained from graphite, through mechanical exfoliation followed by calcination and ultrasonic agitation in an oxidant solution. These samples were characterized under SEM, FTIR, Raman spectroscopy, UV-vis and R-X techniques. On the other hand, H2T(p-NH2)PP was synthesized in two steps?process by the Rothemun reaction and the Adler Method and it was integrated within nylon polyamide fibers by direct addition of a hexamethylenediamine/adipoyl chloride reactant mixture. The polymerization of the nylon/H2T(p-NH2)PP species occurs in such a way that it starts or ends on the four peripherals-NH2 groups, connected and located in the same molecular plane of H2T(p-NH2)PP, forming nylon chains at the periphery of the macrocycle. The association of GO with nylon/H2T(p-NH2)PP fibers is performed
Implicaciones fisiológicas de la osmorregulación en plantas
Agronomía Colombiana , 2006,
Abstract: under natural conditions, the plants are exposed to changing environmental conditions that determine complex respuests that influence in the growth, development and productivity of the crops. the conditions of drought and salinity in the soils are the greater causes of stress in the crops and cause lost economic in the world agriculture. the drought as the salinity are osmotic stress that inhibits the growth and cause interferences at metabolic level. the recognition of the biochemical and physiologic mechanisms involved in the osmoregulation involved in the osmotic stress allows to implement new strategies for the handling and improvement of the cultivations under conditions of stress hidric and saline. different mechanisms are recognized through which the plants manage to adapt and to tolerate the changes in the water potential, between which stand: the water transport by acuaporins, the estomatic closing, the synthesis of compatible osmolites, the ión transport through selective systems of sodium and potassium and those not selective located in the biological membranes and the etrution and compartimentalization of sodium. the osmoregulation confers to the plants the capacity to tolerate conditions of drought and high salinity, with the expression of adaptative mechanisms that avoid the reduction of the photosynthesis, alterations in the allocation photoasimilates and losses in yield, facts that have significant transcendency in the normal physiology of the plant and in the productivity of the crops. the present review has as central objective, to report the discoveries more recent envelope the smorregulation process in exposed cultivated plants to stress by water deficit and by salinity in the soils.
Implicaciones fisiológicas de la osmorregulación en plantas
Rodríguez-Pérez Loyla
Agronomía Colombiana , 2006,
II Seminario Científico Internacional sobre Medicina Veterinaria AGROCIENCIAS2009
Rodríguez-Pérez, Fructuoso
REDVET , 2009,
Abstract: ResumenLa Facultad de Medicina Veterinaria de la Universidad Agraria de laHabana convoca al II Seminario Científico Internacional sobreMedicina Veterinaria, el cual se celebrará en el marco del CongresoInternacional de las Ciencias Agropecuarias “Agrociencias 2009” aefectuarse durante los días 8 al 10 de Julio de 2009, con el objetivo de propiciar un espacio para que especialistas extranjeros y nacionales en diferentes campos de las Ciencias Veterinarias, puedan encontrarse e intercambiar criterios sobre el desarrollo alcanzado en los temas que serán abordados.
Orbital entanglement production in Andreev billiards with time-reversal symmetry
Sergio Rodríguez-Pérez,Marcel Novaes
Physics , 2013,
Abstract: We study orbital entanglement production in a chaotic cavity connected to four single-channel normal-metal leads and one superconducting lead, assuming the presence of time-reversal symmetry (TRS). The scattered state of two incident electrons is written as the superposition of several two-outgoing quasi-particle states, four of which are orbitally entangled in a left-right bipartition. We calculate numerically the mean value of the squared norm of each scattered state's component, as functions of the number of channels in the superconducting lead. Its behavior is explained as resulting from the proximity effect. We also study statistically the amount of entanglement carried by each pair of outgoing quasi-particles. When the influence of the superconductor is more intense, the average entanglement is found to be considerably larger than that obtained using normal cavities.
Genome-wide comparison inferred the origin and evolution of B-cell epitopes on the proteins of human influenza A virus  [PDF]
Edgar E. Lara-Ramírez, Aldo Segura-Cabrera, Ma. Isabel Salazar, Mario A. Rodríguez-Pérez, Xianwu Guo
Health (Health) , 2012, DOI: 10.4236/health.2012.430145
Abstract: The novel strain H1N1 caused the outbreak of first pandemic influenza in 21 century. Now it is a common component of current seasonal influenza viruses. The recent transmission and plentiful genome sequences available provided a good opportunity to study the origin and evolution of epitopes on the proteins of human influenza virus. In the present study, the B-cell epitope compositions in the pandemic strains, circulating traditional seasonal strains, swine strains as well as highly virulent avian strain H5N1 were identified with the aid of the Immune Epitope DataBase (IEDB) and were compared at genomic level. A total of 14210 distinct sequences down-loaded from NCBI database were used for analysis. Some epitopes on proteins HA or NA, not conserved in recent seasonal strains, were found in 2009 pandemic strains but existed in the early human strains (1919-1935). The pandemic strain shared higher conserved epitopes with “bird flu” virus H5N1than classic human seasonal strains. The epitopes that could exist at common antigenic regions of HA protein are needed to further identify. The genetic exchanges between human and swine population by transmission was very active but the princepal side of the transmission could be from swine to human. These results provided valuable information on influenza A virus evolution and transmission by means of epitope analysis at genomic level.
Modelling and experimental contrast of the mechanical behaviour of structural laminated glass
Sanz-Ablanedo, E.,Lamela, M. J.,Rodríguez-Pérez, José R.,Arias, P.
Materiales de Construccion , 2010,
Abstract: This paper presents a numerical simulation of the mechanical behaviour of laminated glass plates (glass- PVB-glass) and its experimental verification. The viscoelastic characterization of the intermediate layer of PVB has been done by means of stress relaxation tests at various temperatures. The consideration of PVB as a viscoelastic material permits to analyze the real response of the structural element of laminated glass under time variations of temperature, of application of loading, of stress state, etc. Displacements obtained with the numerical analysis have been verified experimentally with laminated glass plates under lateral load using close range photogrammetry and dial gauges indicators. The analysis of results confirms the time dependent behaviour of the glass-PVB-glass laminate and suggests the validity of the proposed model. Este trabajo presenta la simulación numérica del comportamiento mecánico de placas de vidrio laminado (vidrio-PVB-vidrio) y su comprobación experimental. La caracterización viscoelástica de la lámina intermedia de PVB se ha realizado mediante ensayos de relajación de tensiones a diversas temperaturas. La consideración del PVB como material viscoelástico permite analizar la respuesta real del elemento estructural de vidrio laminado ante variaciones en el tiempo de la temperatura, de la velocidad de aplicación de las cargas, del estado tensional, etc. Los desplazamientos obtenidos numéricamente han sido contrastados experimentalmente en placas de vidrio laminado sometidas a carga lateral mediante fotogrametría de objeto cercano y relojes comparadores. Del análisis de los resultados se confirma el comportamiento variable en el tiempo del conjunto vidrio-PVB-vidrio y se deduce la validez de la modelización propuesta.
Predicting Spatial Patterns of Plant Recruitment Using Animal-Displacement Kernels
Luis Santamaría, Javier Rodríguez-Pérez, Asier R. Larrinaga, Beatriz Pias
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0001008
Abstract: For plants dispersed by frugivores, spatial patterns of recruitment are primarily influenced by the spatial arrangement and characteristics of parent plants, the digestive characteristics, feeding behaviour and movement patterns of animal dispersers, and the structure of the habitat matrix. We used an individual-based, spatially-explicit framework to characterize seed dispersal and seedling fate in an endangered, insular plant-disperser system: the endemic shrub Daphne rodriguezii and its exclusive disperser, the endemic lizard Podarcis lilfordi. Plant recruitment kernels were chiefly determined by the disperser's patterns of space utilization (i.e. the lizard's displacement kernels), the position of the various plant individuals in relation to them, and habitat structure (vegetation cover vs. bare soil). In contrast to our expectations, seed gut-passage rate and its effects on germination, and lizard speed-of-movement, habitat choice and activity rhythm were of minor importance. Predicted plant recruitment kernels were strongly anisotropic and fine-grained, preventing their description using one-dimensional, frequency-distance curves. We found a general trade-off between recruitment probability and dispersal distance; however, optimal recruitment sites were not necessarily associated to sites of maximal adult-plant density. Conservation efforts aimed at enhancing the regeneration of endangered plant-disperser systems may gain in efficacy by manipulating the spatial distribution of dispersers (e.g. through the creation of refuges and feeding sites) to create areas favourable to plant recruitment.
Effects of Frugivore Preferences and Habitat Heterogeneity on Seed Rain: A Multi-Scale Analysis
Javier Rodríguez-Pérez, Asier R. Larrinaga, Luis Santamaría
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033246
Abstract: Seed rain mediated by frugivores is influenced by (1) the seed-deposition distances following fruit ingestion, (2) the disperser activity, as determined by its behaviour and habitat preferences, and (3) the structure of the habitat within the landscape. Here, we evaluated such components using the fleshy-fruited shrub Ephedra fragilis and the frugivorous Balearic lizard Podarcis lilfordi. We estimated seed-deposition patterns based on the displacements and habitat preferences of lizards, derived from visual surveys and telemetry data. The influence of variables potentially determining lizard habitat preference (i.e., height, slope, four measures of habitat abundance and four measures of habitat fragmentation) was evaluated at three spatial scales: ‘home-range’ (c. 2.5–10*103 m2; telemetry data), ‘within home-range’ (c. 100 m2; telemetry data) and ‘microhabitat’ (<100 m2; visual survey). Cumulative lizard displacement (from each telemetric location to the initial capture point) saturated before the peak of seed defecation (seed-retention time), indicating that lizard home-range size and habitat preferences were the main determinants of the spread and shape of seed shadows. Shrub cover was positively correlated with habitat preference at the three scales of analysis, whereas slope was negatively correlated at the home-range scale. Model scenarios indicated that spatially-aggregated seed rain emerged when we incorporated the joint effect of habitat preference at the two largest (home-range and within home-range) scales. We conclude that, in order to predict seed rain in animal dispersed plants, it is important to consider the multi-scale effects of habitat preference by frugivores.
Tuberculosis ganglionar cervical: ?Pensamos en ella, o nos sorprende?
Rodríguez-Pérez,Miguel Alberto; Aguirre-García,Fernando;
Revista de otorrinolaringología y cirugía de cabeza y cuello , 2012, DOI: 10.4067/S0718-48162012000100009
Abstract: we review tuberculosis clinical features, diagnosis and management as well as remark the importance of its epidemic nature. study based on 2 patients suffering from eye-catching subacute neck lumps, sparsely symptomatic and excellent evolution after neck node tb diagnosis and antibiotic therapy tb represents a disease that, given our present time globalization, may be faced by many different specialists. that is why we must be on alert and be aware of its profile, in order to guess the right diagnosis and offer therapy.
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