¿Son los alumnos capaces de atribuir a los microorganismos algunas transformaciones de los alimentos?

In this paper we investigate if primary school students are able to relate microorganisms with food transformations. The subjects of this study were 343 4th. and 7th. grade children from Lugo (Spain) and the instrument used consisted of four multiple choice questions. The results shed light on the difficulties students have at these levels when they try to apply their ideas to interpret biological phenomena. Finally, we discuss some implications for Science teaching and learning

Permeabilidad de gases en membranas de zeolita ZSM-5

El trabajo incluido en el presente articulo tiene como objetivo analizar la influencia de la deposición de zeolita ZSM-5 en un tubo de alumina sobre la velocidad de transferencia de materia de distintos gases con el fin de analizar la capacidad de separación. Se ha evaluado la influencia de la presencia de zeolita, así como del caudal de gas alimentado y la temperatura a la que se desarrolla el proceso deseparación

Detección cuantitativa de microorganismos resistentes a la tetraciclina en carne convencional y ecológica de ternera, cerdo y pollo

The use of antimicrobials has increased the number of resistant bacteria to these drugs; however, the organic production has restricted the use of these compounds. The objectives of this work were to assess counts of tetracycline-resistant bacteria using conventional microbiology, to compare these results with those obtained for tet(A) and tet(B) genes by qPCR and to investigate both genes in conventional and organic meat. Counts of mesophilic aerobic bacteria were higher in organic beef, while chicken meat obtained higher counts for Enterobacteriaceae. Only tet(B) was higher in conventional pork and chicken meat than in their organic counterparts. The tet(A) gene was found in almost 100% of samples and tet(B) gene changed according to the type of meat. The presence of tet genes suggests that they are widely distributed, especially tet(A), in food of animal origin, even in organic meat samples obtained from animals in which the use of antimicrobials is restrictedEl uso de los antimicrobianos ha incrementado sustancialmente el número de bacterias resistentes a estos fármacos sin embargo, la producción ecológica, ha limitado el uso de estos medicamentos. Los objetivos del trabajo fueron evaluar los recuentos obtenidos de bacterias resistentes a tetraciclina mediante microbiología convencional, obtener recuentos de bacterias con los genes tet(A) y tet(B)mediante qPCR e investigar la distribución de ambos genes en carne convencional y ecológica. Los recuentos de bacterias aerobias mesófilas fueron significativamente mayores en carne ecológica de ternera, mientras que los recuentos de Enterobacteriaceae fueron superiores en carne convencional de pollo. Sólo el gen tet(B) fue significativamente mayor en carne convencional de cerdo y de pollo que en sus homólogas ecológicas. El gen tet(A) se encontró en casi todas las muestras mientras que el tet(B) varió según la especie. La presencia de los genes tet sugiere que están ampliamente distribuidos, especialmente tet(A), en alimentos de origen animal, incluso en aquellos derivados de animales en los que el uso de antimicrobianos está seriamente restringidoThe authors are grateful to the Institute Pasteur for providing the E. coli BM13 (C600 RifR)/RP4 strain (tet(A)) and to the Health Protection Agency for providing the E. coli NCTC 50365 strain (tet(B)). Xunta de Galicia (project 09MRU010261PR) supported this work. We also thank Carmen Carreira and Rodrigo García for their technical supportS

Resistance and inactivation kinetics of bacterial strains isolated from the Non-chlorinated and chlorinated effluents of a WWTP

The microbiological quality of water from a wastewater treatment plant that uses sodium hypochlorite as a disinfectant was assessed. Mesophilic aerobic bacteria were not removed efficiently. This fact allowed for the isolation of several bacterial strains from the effluents. Molecular identification indicated that the strains were related to Aeromonas hydrophila, Escherichia coli (three strains), Enterobacter cloacae, Kluyvera cryocrescens (three strains), Kluyvera intermedia, Citrobacter freundii (two strains), Bacillus sp. and Enterobacter sp. The first five strains, which were isolated from the non-chlorinated effluent, were used to test resistance to chlorine disinfection using three sets of variables: disinfectant concentration (8, 20 and 30 mg·L−1), contact time (0, 15 and 30 min) and water temperature (20, 25 and 30 °C). The results demonstrated that the strains have independent responses to experimental conditions and that the most efficient treatment was an 8 mg·L−1 dose of disinfectant at a temperature of 20 °C for 30 min. The other eight strains, which were isolated from the chlorinated effluent, were used to analyze inactivation kinetics using the disinfectant at a dose of 15 mg·L−1 with various retention times (0, 10, 20, 30, 60 and 90 min). The results indicated that during the inactivation process, there was no relationship between removal percentage and retention time and that the strains have no common response to the treatmentsThe work of SM-H was supported by a graduate scholarship (number 217745) that was kindly provided by CONACyT, Mexico. Some chemical reagents were generously provided by the Administration of the B.A. in Biology at UAEH, Mexico. We thank the Instituto Tecnológico de Estudios Superiores de Monterrey, Hidalgo campus, for allowing us to sample from its WWTP. The authors recognize Jose A. Rodriguez-Ávila for his comments on the procedure for analyzing inactivation kineticsS

Synchrotron radiation as probe for copper oxidation states in glass

ICOM Committee for Conservation (ICOM-CC). Glass and Ceramics Working Group. Interim meeting, and ICOMOS International Scientific Committee for the Conservation of Stained Glass (Corpus Vitrearum-ICOMOS). Forum, Amsterdam, The Netherlands, 2013.In this study, synchrotron radiation was used explore the relationship between degradation of some historical glasses of different provenance and dating and the oxidation state of their colouring agents. tje oxidation states of copper in red and green glasses were monitored by recording spectra at the Cu K-edge by X-ray absorption near edge structure Promissing results with this new analytical tool may extend knowledge about glass decay.The Spanish Ministry of Economy and Competitiveness (SMEC) and CSIC is acknowledged for the financial support. This work has been supported by the SMEC through the projects FIS-2008-06249, S2009-MAT-1629 (Geo-materials Program) and MAT2011-27573-C04-04; further support has been given by the Comunidad de Madrid NANOBIOMAGNET project and by the Aragón DGA NETOSHIMA grant. NC acknowledges the financial support of the FSE-MEC Ramón y Cajal Program. MA and AS acknowledge the UCM Campus of International Excellence (PICATA Program) and the CSIC (JAE Program), respectively, for pre-doctoral fellowships.Peer reviewe