Synthesis and Characterization of Amide Stationary Phases for the Determination of Sulfonamides by Sequential Injection Chromatography

Producción CientíficaThe synthesis of amide (butyl, cyclohexyl, and phenyl) modified silica and the use as stationary phases in sequential injection chromatogra-phy are described. The system was tested on the isocratic separation of seven sulfonamides (sulfachloropyridazine, sulfadimethoxine, sulfame-thazine, sulfamethoxazole, sulfamethoxypyridazine, sulfaquinoxaline, and sulfathiazole) using each stationary phase with mobile phases composed of acetonitrile/water at a flow rate of 0.45 mL min−1. A mixed mode retention mechanism of sulfonamides in the stationary phases was obtained, including dipole-dipole, π-π, and hydrogen bonding interactions. The most appropriate phase for the separation of sulfonamides was phenylamide. The chromatographic behavior was confirmed using density functional theory of the interaction between sulfamethoxazole and the stationary phases.Junta de Castilla y León Proyecto VA171U1

Comparative exploration of the morphological plasticity of Trichodina centrostrigeata (Peritrichia: Mobilida), ectoparasite from the gills of two tilapia species (Oreochromis niloticus and O. mossambicus) in a global context

Trichodina centrostrigeata Basson, Van As et Paperna, 1983 from Oreochromis mossambicus (Peters) and O. niloticus (Linnaeus) from different host populations from Argentina, Mexico and South Africa was reviewed. Although T. centrostrigeata has a distinct denticle structure that makes morphological taxonomic inferences uncomplicated, variation of the denticles within and among individuals and populations were still observed. While traditional taxonomy of mobilines is heavily reliant on morphometrics, and recently even more so on molecular analysis, this paper proposes the use of geometric morphometry, specifically elliptical Fourier analysis, to address morphological conflicts that arise when comparing different populations. By applying this technique, combined with traditional taxonomy, it was found that T. centrostrigeata in this study can be grouped into two separate morphotypes, the first (type a) from aquaculture farms in Argentina and Mexico and the second (type b) from a natural habitat in Glen Alpine Dam, South Africa. This study supports the validity of geometric morphometry as an additional technique to distinguish not only between species but also evolutionary plasticity of the same species from different localities and habitats.Fil: Islas-Ortega, Alma Gabriela. Universidad Nacional Autónoma de México. Instituto de Biología; MéxicoFil: Marcotegui, Paula Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Basson, Linda. University of the Free State; SudáfricaFil: de Jager, Gerhard P.. University of the Free State; SudáfricaFil: Aguilar Aguilar, Rogelio. Universidad Nacional Autónoma de México. Instituto de Biología; Méxic

Analysis of the effect of El Niño and La Niña on Tecocomulco Lake, central basin, Mexico

Tecocomulco Lake is a relic of the great basin of the central plateau of Mexico. Its surface area changes in response to both the variation in the inputs from inland areas and the effects of the climatic phenomena of El Niño and La Niña. It is endorreic, with a low rainfall and a low and intermittent fluvial input, a high evaporation, and a considerable influx of sediment due to deforestation and a bad management of the basin. The most important plant species is Schoenoplectus californicus that grows massively in muddy areas, decreasing the depth and reducing the flooded area. The lake is visited by birds from USA and Canada, that arrive to nest and reproduce. During the extremely dry years that coincide with the El Niño, approximately 9% of the dry surface is used by the local inhabitants as cropland, which generates a social problem during the extremely rainy years that coincide with the La Niña when the lake area increases and floods the cultivated land. In the 2001-2002 El Niño, the surface of Tecocomulco Lake decreased by 37% and the depth was 0.75-1 m. This may be associated with a higher temperature, and in consequence a high evaporation, a situation that requires corroboration through future studies

Dispersive solid phase extraction based on butylamide silica for determination of sulfamethoxazole in milk samples by capillary electrophoresis

A new method based on the combination of dispersive solid-phase extraction and capillary electrophoresis is proposed for the determination of sulfamethoxazole in milk samples. Butylamide silica was synthesized and used as extractant. Factors involved in sample treatment method such as: butylamide silica amount, NaOH concentration in methanol, sample volume, and dispersion time were evaluated using a Taguchi parameter design. Under optimal conditions, average recoveries ranged from 73 to 85% with a limit of detection of 0.05 mg L 1 were achieved. The proposed method is a useful technique for cleanup milk samples.Junta de Castilla y León Proyecto VA171U1

Effects of peppermint extract and chitosan-based edible coating on storage quality of common carp (Cyprinus carpio) fillets

Artículo internacional en revista indizadaEdible coatings have recently been developed and applied to different food matrices, due to their numerous benefits, such as increasing the shelf life of foods, improving their appearance, being vehicles of different compounds, such as extracts or oils of various spices that have antioxidant and antimicrobial activity, as well as being friendly to the environment. The objective of this research was to develop a new edible coating based on chitosan enriched with peppermint extract and to evaluate its effectiveness to inhibit microbial development in vitro and improve both the quality and shelf life of common carp (Cyprinus carpio) during refrigerated storage (4 ± 1 C). Three treatments were used: edible coating (C + EC), edible coating +, 5% chitosan (C + ECCh) and edible coating + 1.5% chitosan + 10% peppermint (C + ECChP). Prior the coating carp fillets; the antibacterial activity and antioxidant capacity were evaluated in the peppermint extract and coating solutions. After coating and during storage, the following were determined on the fillet samples: microbiological properties, observed for ECP, an inhibition halo of 14.3 mm for Staphylococcus aureus, not being the case for Gram-negative species, for ECCh, inhibition halos of 17.6 mm, 17.1 mm and 16.5 mm for S. aureus, Salmonella typhimurium and Escherichia coli, respectively; for the ECChP, inhibition halos for S. aureus, S. typhimurium and E. coli of 20 mm, 17 mm and 16.8 mm, respectively. For the physicochemical characteristics: an increase in solubility was observed for all treatments during storage, reaching 46.7 mg SN protein/mg total protein for the control, and values below 29.1 mg SN protein/mg total protein (p C + ECCh > C + ECChP, respectively at the end of storage. For the pH, maximum values were obtained for the control of 6.4, while for the fillets with EC a maximum of 5.8. For TVB-N, the fillets with different CE treatments obtained values (p C + E C > C + ECCh > C + ECChP respectively). Total phenolic compounds in the aqueous peppermint extract were 505.55 mg GAE/100 g dried leaves, with 98.78% antioxidant capacity in the aqueous extract and 81.88% in the EC. Biomolecule oxidation (hydroperoxide content) had a significant increase (p < 0.05) in all treatments during storage, 1.7 mM CHP/mg protein in the control, to 1.4 in C + EC, 1.27 in C + ECCh and 1.16 in C + ECChP; TBARS assay values increased in the different treatments during refrigerated storage, with final values of 33.44, 31.88, 29.40 and 29.21 mM MDA/mg protein in the control; C + EC; C + ECCh and C + ECChP respectively. In SDS -PAGE a protective effect was observed in the myofibrillar proteins of fillets with ECChP). The results indicate that the C + ECCh and C + ECChP treatments extend the shelf life of 3–5 days with respect to microbiological properties and 4–5 days with respect to physicochemical characteristics. A reduction in lipid and protein oxidation products was also observed during refrigerated storage. With these findings, this is considered a promising method to increase the shelf life of fish fillets combined with refrigeration and we are able to recommend this technology for the fish processing industry.Consejo Nacional de Ciencia y Tecnologí

Recursos audiovisuales en la educación en enfermería: revisión de la literatura

Introduction: Audiovisual aids, as a teaching strategy, promote a change from the traditional educational system to an improved way of learning that integrates technological advances and resources to enhance education, this is why it is important to gather all the existent information about the topic, because we need to demonstrate and support its’ usage for the students development. Aim:Analyze the existent information about the impact that audiovisual aids have in the improvement or nursing teaching.Methodology: Systematic research in the Medina, CINAHL, EBSCO, SciELO, PubMed, LILACS and Cochrane databases. Using de PICo method and Health Science Descriptors (DeCS) in English, Spanish and Portuguese. Results: Seven experimental and quasi-experimental studies were selected, which showed that audiovisual aids helped in the improvement of declarative, contextual and attitudinal learning, nevertheless, they did not surpass the situated strategies such as simulations, authorized practices and interactive activities. Conclusion: The evidence showed that the use of audiovisual aids developed empathy and helped the students’ inner expression, however they are not able to outstep the constructive learning strategies by themselves.Introducción. Los recursos audiovisuales como estrategias de enseñanza fomentan el cambio de una educación tradicional hacia una que integra los cambios tecnológicos, la cual utiliza y dispone de los recursos para mejorar el aprendizaje, por lo que es necesario contar con la mejor evidencia disponible para apoyar su utilización en la formación de los estudiantes.Objetivo. Analizar la evidencia existente del impacto que tienen los recursos audiovisuales en el mejoramiento de la enseñanza en enfermería.Metodología. Búsqueda sistematizada en las bases de datos Medline, CINAHL, EBSCO, SciELO, ERIC, PubMed, LILACS y Cochrane. Utilizando el método PICo y Descriptores de Ciencias de la Salud (DeSC) en inglés, español y portugués.Resultados. Se seleccionaron 7 estudios experimentales y cuasi-experimentales dónde se observa que los recursos audiovisuales ayudan a mejorar el aprendizaje declarativo, contextual y actitudinal, sin embargo, no superan a las estrategias situadas como la simulación, práctica tutorizada y actividades interactivas.Conclusiones. La evidencia demuestra que el uso de los recursos audiovisuales desarrolla la empatía y favorece la expresión de la interioridad del alumno, sin embargo, por sí solos no superan a estrategias de aprendizaje constructivistas.

Recombinant expression of marine shrimp lysozyme in Escherichia coli

Shrimp Lysozyme (Lyz) is a key component of the antibacterial response as part of the innate defense in Crustacea; however, it has not been possible to purify this protein because of the very low amount present in the shrimp blood cells (hemocytes). In an effort to produce enough protein to study its function and biochemical properties we have overexpressed Lysozyme from marine shrimp ( Penaeus vannamei ) in E. coli. A bacterial protein expression system based on the T7 polymerase promoter was used. Although Lyz was produced as insoluble protein in inclusion bodies, its refolding led to an active protein with a yield of ~10%. Details of the protein recombinant expression techniques applied to this shrimp protein are presented

Determinación de glifosato y ácido aminometilfosfónico en suelos mediante hplc con derivatización pre-columna

La disminución en las expectativas de producción debido a la incidencia de plagas y enfermedades provocó un incremento en la aplicación de herbicidas con la finalidad de aumentar la capacidad agrícola. La interferencia de la maleza en los cultivos ocasiona pérdidas en el rendimiento y calidad de los productos cosechados. Las prácticas realizadas para su control incrementan los costos de producción. La maleza puede ser controlada en forma mecánica, biológica o química. El control mecánico consiste en la eliminación de las mismas con algún elemento que las dañe o extraiga, el control biológico es un método de control basado en principios ecológicos que usa enemigos naturales específicos de una planta (Rosenthal S.S, 1984). El control químico se realiza por medio de la aplicación de herbicidas, que inhiben o interrumpen el crecimiento y desarrollo de una planta. En la actualidad el control químico es una de las principales herramientas en la agricultura moderna (Anderson W.P, 1996)

Evaluación electroquímica de recubrimientos anticorrosivos en condiciones de alta presión

Tesis de Maestría presentada a la Facultad de Ingeniería de la Universidad Veracruzana. Región Veracruz

Telefonía móvil: espacio híbrido para las prácticas artísticas Telefonía móvil: espacio híbrido para las prácticas artísticas

The paper approaches the use of mobile technologies within art, being the telephone in our special interest. These objects are studied, and the experiences created by them that in most cases do not take place in a specific site. They can occur in a virtual and temporary space.These practices require the active participation of the beholder who becomes a co-author of the piece. The works of art that are analyzed have all these characteristics and show the complexity between the mobile technology and the user.El ensayo aborda el uso de ciertas tecnologías móviles, en especial la telefónica, dentro del campo artístico. Se examina el uso de estos objetos para crear experiencias artísticas que enla mayoría de los casos quedan fuera de un lugar específico, es decir que pueden ser en unespacio virtual y temporal. Además estas prácticas requieren de la participación activa del espectadorquien se convierte en coautor. Las obras que se analizan reúnen estas característicasy muestran la complejidad entre la tecnología móvil y el usuario