Woolrich-Pina G.A.,Puebla Institute of Technology |
Smith G.R.,Denison University |
Benitez-Tadeo R.A.,Simón Bolívar University of Mexico |
Lemos-Espinal J.A.,National Autonomous University of Mexico |
Morales-Garza M.,Simón Bolívar University of Mexico
Copeia | Year: 2017
High levels of salinity often have lethal and sublethal effects on amphibians. In Mexico, salinization is threatening some rivers in arid and semi-arid regions. Here, we report the results of an experiment examining the effects of salinity and density on Pine Toad (Incilius occidentalis) tadpoles from the Río El Sabino in the Tecomavaca Canyon in Oaxaca, Mexico. Tadpoles of Incilius occidentalis from Oaxaca were not affected by salinities up to 0.8 ppt in either survivorship or total length. Our results for survivorship and total length are consistent with results from another population of I. occidentalis from the Río Salado in Puebla, Mexico. We found that density reduced total length (i.e., growth) but not survivorship, whereas similar densities did not affect survivorship or size at metamorphosis in the tadpoles from the Río Salado. These results suggest the potential for the existence of differences in the larval ecology of I. occidentalis from these two populations. © 2017 by the American Society of Ichthyologists and Herpetologists.
Garcia-Hernandez E.,Metropolitan Autonomous University |
Garcia-Hernandez E.,Puebla Institute of Technology |
Flores-Moreno R.,University of Guadalajara |
Vazquez-Mayagoitia A.,Argonne National Laboratory |
And 2 more authors.
New Journal of Chemistry | Year: 2017
Three of the most important compounds in the insecticide industry, imidacloprid (IMI), thiacloprid (THIA) and acetamiprid (ACE), are theoretically analyzed. Wave-function and density functional theory (DFT) were used for the conformational analysis of the three compounds. In the context of conceptual DFT, by analyzing the local electrodonating power for the first stage of the degradation of these insecticides, we found that for THIA and ACE, solvated or free, there is more than one site where the electron is detached. Usually, just one nitrogen atom from the imidazolidine group is considered for the first step in the degradation process. However, in this work we propose at least one additional site for these two compounds, which involves another nitrogen atom. In addition, the theoretical approach presented in this article predicts one acetamiprid tautomer, which gives one additional site to detach one electron. Such a possibility has not been proposed before and to experimentally search new pathways for the degradation of these insecticides can give important information. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Velasco A.,Metropolitan Autonomous University |
Aburto-Medina A.,RMIT University |
Aburto-Medina A.,Puebla Institute of Technology |
Shahsavari E.,RMIT University |
And 2 more authors.
Journal of Hazardous Materials | Year: 2017
Abiotic and biotic processes can be used to remediate DDX (DDT, DDD, DDE, and DDNS) contaminated soils; these processes can be fostered using specific carbon-amendments to stimulate particular soil indigenous microbial communities to improve rates or extent of degradation. In this study, toluene and glycerol were evaluated as cosubstrates under aerobic and anoxic conditions to determine the degradation efficiencies of DDX and to elucidate possible degradation mechanisms. Slurry microcosms experiments were performed during 60 days using pretreated soil with zero-valent iron (ZVI). Toluene addition enhanced the percentage of degradation of DDX. DDNS was the main compound degraded (around 86%) under aerobic conditions, suggesting cometabolic degradation of DDX by toluene-degrading soil bacteria. Glycerol addition under anoxic conditions favored the abiotic degradation of DDX mediated by sulfate-reducing bacteria activity, where DDT was the main compound degraded (around 90%). The 16S rDNA metagenomic analyses revealed Rhodococcus ruber and Desulfosporosinus auripigmenti as the predominant bacterial species after 40 days of treatment with toluene and glycerol additions, respectively. This study provides evidence of biotic and abiotic DDX degradation by the addition of toluene and glycerol as cosubstrates in ZVI pretreated DDX-contaminated soil. © 2016 Elsevier B.V.
Estrada-Medina H.,Autonomous University of Yucatán |
Graham R.C.,University of California at Riverside |
Allen M.F.,University of California at Riverside |
Jimenez-Osornio J.J.,Autonomous University of Yucatán |
Robles-Casolco S.,Puebla Institute of Technology
Plant and Soil | Year: 2013
Background and Aims: With limited soil depth in northern Yucatán (<30 cm), roots grow deeper through rock fractures and dissolution karst features (i. e., cavities, including soil-filled ones known as soil pockets). We assessed the importance of limestone bedrock and dissolution karst features on tree root growth. Methods: Fieldwork was conducted in a limestone quarry where the relative proportions of rock matrix, empty cavities, and soil pockets were calculated by observing recently exposed walls. Physical properties of rocks, topsoil, and soil pockets were analyzed. Root distribution was assessed and roots identified. Results: Soil pockets represented 9% of the rock matrix. The physical properties of rock layers were different with depth. Available water capacity is higher in soil (0. 11 m-3 m-3) than in rock layers (<0. 05 m-3 m-3). But potential available water was much higher in subsurface features than top soil. Conclusions: Dissolution karts features allow roots to grow deep into the bedrock, tapping water stored there. Although the limestone upper layer in northern Yucatan is highly restrictive to root growth, subsurface limestone layers and soil pockets are not restrictive and can hold important amounts of water. © 2012 Springer Science+Business Media B.V.
Ayon-Beato E.,CINVESTAV |
Ayon-Beato E.,Austral University of Chile |
Bravo-Gaete M.,University of Talca |
Correa F.,Leibniz University of Hanover |
And 5 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
The aim of this paper is to confirm in new concrete examples that the semiclassical entropy of a three-dimensional Lifshitz black hole can be recovered through an anisotropic generalization of the Cardy formula derived from the growth of the number of states of a boundary nonrelativistic field theory. The role of the ground state in the bulk is played by the corresponding Lifshitz soliton obtained by a double Wick rotation. In order to achieve this task, we consider a scalar field nonminimally coupled to new massive gravity for which we study different classes of Lifshitz black holes as well as their respective solitons, including new solutions for a dynamical exponent z=3. The masses of the black holes and solitons are computed using the quasilocal formulation of conserved charges recently proposed by Gim et al. and based on the off-shell extension of the ADT formalism. We confirm the anisotropic Cardy formula for each of these examples, providing a stronger base for its general validity. Consistently, the first law of thermodynamics together with a Smarr formula are also verified. © 2015 American Physical Society.
Sepulveda-Cervantes G.,Cidetec |
Portilla-Flores E.A.,Puebla Institute of Technology
Applied Mathematics and Information Sciences | Year: 2015
This work presents a novel method for haptic rendering contact force and surface properties for virtual objects using the Conformal Geometric Algebra orthogonal decomposition approach. The mathematical representation of geometric primitives along with collision algorithms based on its mathematical properties is presented. The orthogonal decomposition of contact and interaction forces is achieved using the same framework and dynamic properties in both subspaces are rendered simultaneously. Comparing with vector calculus, the Conformal Geometric Algebra (CGA) approach provides an easier and more intuitive way to deal with haptic rendering problems due to its inner properties and a simpler representation of geometric objects and linear transformation. The results of the evaluation of the method using a 3 DOF haptic device are presented. © 2015 NSP.
Majewski T.,Universidad de Las Americas Puebla |
Szwedowicz D.,CENIDET |
Melo M.A.M.,Puebla Institute of Technology
Journal of Sound and Vibration | Year: 2015
This paper presents an analysis of the automatic balancing of a rigid disk mounted on an elastic shaft. The balancing system consists of two drums at a variable distance from the disk and free balls (or rollers) inside the disk. The balls are able to change positions with respect to the rotor and compensate for rotor unbalance. This paper presents the equations of motion for the disk as well as for the balls during balancing. It is shown that the balls can compensate a part or all of the rotor unbalance depending on the positioning of the drums. There are vibratory forces that push the balls to new positions; these are responsible for the behavior of the balls and the final results. The vibratory forces are defined as a function of the system's parameters and they determine the position of equilibrium of the balls. The stability and efficiency of the method is analyzed in this paper. © 2015 Elsevier Ltd.
Mejias-Brizuela N.Y.,National Institute of Astrophysics, Optics and Electronics |
Olivares Perez A.,National Institute of Astrophysics, Optics and Electronics |
Grande Grande A.,Puebla Institute of Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
We present the behaviors in the time of the diffraction efficiency of holographic gratings, there were recorded in two monosaccharides, glucose and fructose, and both were sensitized with potassium dichromate and blue dye. There monosaccharides present diffraction efficiency with a maximum of 7% approximately, without protection, the sample exposure at environmental conditions, after 48 hours the parameter of diffraction efficiency decays. By this reason is necessary to protect after of the stabilized emulsion the hologram. © 2009 Copyright SPIE - The International Society for Optical Engineering.
Valdez S.,National Autonomous University of Mexico |
Pech-Canul M.I.,CINVESTAV |
Ascencio-Gutierrez J.A.,National Autonomous University of Mexico |
Casolco S.R.,Puebla Institute of Technology
International Journal of Electrochemical Science | Year: 2013
The chemical composition of metallic AlZnAg alloy is related with microstructure in order to know their influence on electrochemical degradation. The microstructure has been characterized by high transmission electron microscopy with energy-dispersive X-ray. The electrochemical behavior has been tested by potentiodynamic polarization tests. In addition, weight loss analysis was carried out for the corrosion rate. In electrochemical tests the results showed the significant influence of silver concentration on the dissolution reactions of Al-matrix, solid solution rich-Zn, and AgZn3 precipitate phase. The electrochemical investigation shows that the corrosion rate increases with the silver additions. Likewise, it was moreover evidenced the development of a film passive layer for the maximum silver content alloys; the passivity of this cover could be broken due to the existence of precipitate phase AgZn3. Based on this behavior the AgZn3 particles, and microstructural phases play a significant role in the corrosion process for the metallic AlZn alloys. © 2013 by ESG.
Jaime V.B.J.,Puebla Institute of Technology
International Journal of ChemTech Research | Year: 2014
A series of ferrocenylmono-and dichalcone derivatives have been synthesized under solvent-free conditions via Claisen-Schmidt condensations between aryl/ferrocenyl ketones and aryl/ferrocenyl aldehydes by just grinding in an agate mortar. All the reactions occur in a short time with excellent yields (>85%) of steroselective trans-conformation in the chalcones. The structures of all the compounds have been characterized by FT-IR, 1H NMR, 13C NMR and EI-MS and elemental analyses.