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Unidad San Miguel Jagüeyes, Mexico

Cetzal-Ix W.,Colegio de Mexico | Cetzal-Ix W.,Research Center Cientifica Of Yucatan Ac Cicy | Carnevali G.,Research Center Cientifica Of Yucatan Ac Cicy | Carnevali G.,Harvard University | Noguera-Savelli E.,Francisco de Montejo
Lankesteriana | Year: 2014

Cohniella amazonica (Orchidaceae, Oncidiinae, Trichocentrum-clade) a species in the Cohniella ascendens complex, from Amazonas, Venezuela, is herein newly described, illustrated, and characterized based on morphological characters. The new taxon is similar to C. nuda, from which it differs in the subquadrateoblong lateral lobes of the labellum that are in the same plane as the central lobe, the 5-partite callus, the bipartite column wings, and the distribution range restricted to the northeastern portion of Amazonas, Venezuela. The conservation status of the new taxon is assessed as Data Deficient (DD) according to the IUCN (International Union for Conservation of Nature) criteria. We provide a key and table of characters to diagnose the Cohniella ascendens species complex, a comparative figure, and a map showing the geographical distributions of the species in this group. © Universidad de Costa Rica, 2014. Source


Mina J.,University of Valle | Valadez-Gonzalez A.,Research Center Cientifica Of Yucatan Ac Cicy | Herrera-Franco P.,Research Center Cientifica Of Yucatan Ac Cicy | Zuluaga F.,University of Valle | Delvasto S.,University of Valle
DYNA (Colombia) | Year: 2011

Thermoplastic starch (TPS) was obtained from natural and acetylated cassava starch using a twin screw extruder and then conditioned at 25°C and 54% of relative humidity. It was found that the crystallinity index, calculated as the ratio of the IR peaks at 1047 (crystalline phase) and 1022 cm-1 (amorphous phase), decreases due to the effect of a plasticization process. Also, as expected, SEM micrographs show that the plasticization process destroyed the starch granular structure almost completely and an amorphous mass was obtained. The TGA results indicated that the activation energy, Ea, was also reduced by the plasticization process. The acetylated TPS shows a decrease in Tg, in tensile strength and in the percentage of moisture absorption compared to natural TPS but a larger strain at the breaking point. This behavior suggests that the chemical modification reduces the secondary interactions between starch chains due to the substitution of the hydroxyl groups by acetates. Source


Vazquez Calderon M.,Biotechnology Unit | Zavala Leon M.J.,Instituto Nacional de Investigaciones Nucleares | Contreras Martin F.A.,Research Center Cientifica Of Yucatan Ac Cicy | Espadas Y Gil F.,Research Center Cientifica Of Yucatan Ac Cicy | And 3 more authors.
Journal of Botany | Year: 2014

In order to generate new varieties, this study focused on the rescue and use of landraces and wild Carica papaya L. populations located at southern Yucatan, Mexico, to cross them with a commercial papaya cultivar (Maradol). In the cross L7 × M22, The native parent line L7 was used as the receiver parent while the commercial Maradol (M22) was used as the donor parent, seeking to generate genotypes with improved productivity and reduced plant height. Cluster analysis and principal components analysis grouped the genotypes firstly into those individuals with few fruits and those with many fruits and secondly into individuals with high and low plant height. Selected genotypes H13B, H17B, H19B, H68B, and H71B meet the desirable characteristics, such as reduced plant height (PH) and intermediate number of fruits per plant (NFP). These materials can be used now to produce new crosses to continue with the ongoing breeding program at CICY, seeking new varieties with higher productivity and adequate plant height, and also these genotypes will be preserved and integrated in the germplasm bank in situ and in vitro for further genetic work and possible exchange with other germplasm collections worldwide. © 2014 Mariela Vázquez Calderón et al. Source


Sosa-Gonzalez W.-E.,Research Center Cientifica Of Yucatan Ac Cicy | Sosa-Gonzalez W.-E.,Autonomous University of Carmen | Del Jesus P.-C.R.,A.P.S. University | De Jesus A.-V.M.,Research Center Cientifica Of Yucatan Ac Cicy
High Performance Polymers | Year: 2014

Sulfonated membranes from highly aromatic copoly(ether-amide)s with sulfonation degrees (SDs) between 20 mol% and 55 mol% were prepared from the combination of diamines, 4,4′-(hexafluoroisopropylidene)-bis-(p-phenyleneoxy)dianiline (HFD), and different molar concentrations of 2,4-diaminobenzenesulfonic acid (DABS) that were reacted with equimolar amounts of isophthalic acid (ISO). The ionic membranes show-SO3H groups in the expected concentrations as assessed by Fourier transform infrared and proton nuclear magnetic resonance. Sulfonated copoly(ether-amide) membranes show the first thermal decomposition at 281°C for the sulfonic moieties and a second thermal loss at 439°C for the rigid nonsulfonated backbone which imparts them their high thermal stability. The ion-exchange capacity and water absorption in the sulfonated copoly(ether-amide)s increase steadily with SD. The copoly(ether-amide) with the larger SD, 55 mol% of DABS, HFD-co-ISO/DABS-55, shows the highest proton conductivity (91 mS cm-1) at 75°C. These results situate HFD-co-ISO/DABS-55 as a possible electrolyte membrane for use in polymer electrolyte membrane fuel cell with high thermal and mechanical stability. © The Author(s) 2014. Source


Lopez-Contreras J.E.,Research Center Cientifica Of Yucatan Ac Cicy | Rico-Arce M.L.,Herbario K | Can-Itza L.L.,Research Center Cientifica Of Yucatan Ac Cicy | de Stefano R.D.,Research Center Cientifica Of Yucatan Ac Cicy
Anales del Jardin Botanico de Madrid | Year: 2015

In the Mexican portion of the Yucatan Peninsula there are three species of Zygia (Leguminosae, Mimosoideae, Ingeae). Their morphological differences and nomenclature are discussed. A key, descriptions, iconography, ecological, phenological, uses and common names are included. Source

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