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Soledad Diez Gutierrez, Mexico

Chapa-Vargas L.,Technological Institute of San Luis Potosi | Robinson S.K.,University of Florida
Ecography | Year: 2013

We studied the effects of habitat composition and distance from edges on nesting success and brood parasitism of forest birds in the Kaskaskia River Bottoms, one of the largest remaining tracts of floodplain forest in the agricultural Midwestern United States. Our goal was to help the private landowners, who have maintained this region in forest cover, enhance the value of these forests for nesting birds. We measured nest predation rates and levels of brood parasitism of four species, the indigo bunting Passerina cyanea, Acadian flycatcher Empidonax virescens, northern cardinal Cardinalis cardinalis and prothonotary warbler Protonotaria citrea in relation to distances from natural and anthropogenic edges and proportion of natural and anthropogenic habitats within fixed radii around nests. We predicted that nesting success would increase with increasing distance from anthropogenic habitats and with increasing land cover in natural habitats. Our results showed no strong effect of any of these variables on avian nesting success, although parasitism levels increased slightly with increasing proportion of agricultural land around nests for two of the species. Nevertheless, nesting success for at least three of these species was much higher than in more fragmented forest tracts elsewhere in the agricultural Midwest where most forest tracts appear to be population sinks for most species. These results suggest that forest tracts in the Kaskaskia may be saturated with nest predators and brood parasites, but are not super-saturated in a way that would cause these tracts to become 'black hole' population sinks. Our data further suggest that, as long as landowners maintain their private landholdings in forest cover, the details of how they manage their land may have little effect on songbird nesting success. These results also suggest that reforestation efforts in areas with many openings may still benefit forest birds. © 2012 The Authors.

Garcia-Maldonado J.Q.,Northwestern Center for Biological Research | Bebout B.M.,Ames Research Center | Celis L.B.,Technological Institute of San Luis Potosi | Lopez-Cortes A.,Northwestern Center for Biological Research
International Microbiology | Year: 2012

Methanogens have been reported in complex microbial communities from hypersaline environments, but little is known about their phylogenetic diversity. In this work, methane concentrations in environmental gas samples were determined while methane production rates were measured in microcosm experiments with competitive and non-competitive substrates. In addition, the phylogenetic diversity of methanogens in microbial mats from two geographical locations was analyzed: the well studied Guerrero Negro hypersaline ecosystem, and a site not previously investigated, namely Laguna San Ignacio, Baja California Sur, Mexico. Methanogenesis in these microbial mats was suspected based on the detection of methane (in the range of 0.00086 to 3.204 %) in environmental gas samples. Microcosm experiments confirmed methane production by the mats and demonstrated that it was promoted only by non-competitive substrates (trimethylamine and methanol), suggesting that methylotrophy is the main characteristic process by which these hypersaline microbial mats produce methane. Phylogenetic analysis of amino acid sequences of the methyl coenzyme-M reductase (mcrA) gene from natural and manipulated samples revealed various methylotrophic methanogens belonging exclusively to the family Methanosarcinaceae. Moderately halophilic microorganisms of the genus Methanohalophilus were predominant (>60 % of mcrA sequences retrieved). Slightly halophilic and marine microorganisms of the genera Methanococcoides and Methanolobus, respectively, were also identified, but in lower abundances.

Medellin-Castillo H.I.,Autonomous University of San Luis Potosi | De J. Garcia-Zugasti P.,Technological Institute of San Luis Potosi | De Lange D.F.,Autonomous University of San Luis Potosi | Colorado-Alonso F.J.,Autonomous University of San Luis Potosi
International Journal of Advanced Manufacturing Technology | Year: 2013

This paper presents a theoretical, numerical and experimental analysis of the allowable (maximum) deep drawing height (DDH) of rectangular cups made of steel. In particular, a new expression to calculate the allowable DDH of rectangular deep drawing, based on the equivalent diameter concept and the volume conservation principle, is proposed and compared with those theoretical expressions currently available in the literature. Finite element method simulations together with experimental data taken from a set of 20 industrial steel parts are used to evaluate the accuracy of each theoretical expression. The results have shown that the new expression has superior precision than those existing in the literature. © 2012 Springer-Verlag London Limited.

Perez-Aguilar N.V.,Technological Institute of San Luis Potosi | Diaz-Flores P.E.,Technological Institute of San Luis Potosi | Diaz-Flores P.E.,Autonomous University of San Luis Potosi | Rangel-Mendez J.R.,Technological Institute of San Luis Potosi
Journal of Colloid and Interface Science | Year: 2011

Oxidized nitrogen-doped multiwall carbon nanotubes (ox-N-MWCNTs), oxidized multiwall carbon nanotubes (ox-MWCNTs), and oxidized single-wall carbon nanotubes (ox-SWCNTs) were evaluated via batch adsorption kinetic experiments to determine the effect of nanotube morphology on the adsorption rate of cadmium. The nanotubes were characterized by HRTEM, XRD and Raman spectroscopy. Cadmium adsorption isotherms were determined at pH 6. Analyses of the kinetic data with an external mass transport model and an intraparticle diffusion model considered two cases: (1) single nanotubes suspended in aqueous solution and (2) agglomerates of nanotubes suspended in aqueous solution. The intraparticle diffusion model produced the best fit to the experimental data. However, only the diffusivity coefficients for single nanotubes suspended in solution were similar to literature values: about 4×10-9, 1×10-9 and 2.4×10-11cm2/s for ox-N-MWCNTs, ox-MWCNTs and ox-SWCNTs, respectively. The morphology of the various carbon nanotubes might determine cadmium diffusivity. The high amount of sidewall pores observed in the single-walled carbon nanotubes could limit cadmium diffusion and account for the slow diffusion rate of 180min. Conversely, the short length, small surface area and bamboo-type morphology observed with nitrogen-doped multiwall carbon nanotubes may account for the relatively fast adsorption rate of 15min as this morphology prevents cadmium diffusion through the internal tubular space of these nanotubes. © 2011 Elsevier Inc.

Huerta-Ocampo J.A.,Technological Institute of San Luis Potosi | de la Rosa A.P.B.,Technological Institute of San Luis Potosi
Current Nutrition and Food Science | Year: 2011

Amaranth is a highly nutritious and non-allergenic crop with remarkable nutraceutical properties. Seed protein extracts following enzymatic digestion have been shown to inhibit Angiotensin Converting Enzyme (ACE). A possible mechanism of action of ACE inhibitor (ACEi) peptides involving the induction of Nitric Oxide (NO) production through endogenous Nitric Oxide Synthase (eNOS) activation has been proposed. The presence of lunasin, a peptide with proven antitumoral properties, has been confirmed in amaranth seeds and the gene encoding the amaranth lunasin peptide appears homologous to the bifunctional inhibitor/lipid transfer protein/seed storage 2S of the albumin family. Amaranth consumption has been shown to improve the plasma lipid profiles in animals. Methanolic extracts of amaranth have demonstrated anti-hyperlipidemic, anti-diabetic and anti-helmintic properties, while aqueous extracts have demonstrated anti-diarrheic, anti-fungal and anti-malarial properties. Specific polyphenols such as rutin, isoquercetin and nicotiflorin and some phenolic acids and amides with antioxidant effects have also been found in amaranth seeds. The aim of this mini-review is to provide an overview of the nutraceutical properties of amaranth. © 2011 Bentham Science Publishers Ltd.

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