Suchergebnisse

El objetivo general de esta investigación mixta es analizar las percepciones de los estudiantes sobre el uso de una aplicación web para el proceso educativo de la Prueba T, considerando la ciencia de datos. Los participantes son 18 estudiantes de la Universidad Nacional Autónoma de México. Los resultados del aprendizaje automático indican que la aplicación web influye positivamente en el aprendizaje sobre las matemáticas, entusiasmo y rol activo de los estudiantes; asimismo, la técnica árbol de decisión identifica 3 modelos predictivos sobre el uso de esta herramienta. En conclusión, los avances tecnológicos permiten que las universidades junto con los maestros actualicen las actividades escolares bajo la modalidad a distancia y construyan nuevos espacios virtuales educativos.

The use of lactic acid bacteria (LAB) to control multiple pathogens that affect different crops was studied, namely, Pseudomonas syringae pv. actinidiae in kiwifruit, Xanthomonas arboricola pv. pruni in Prunus and Xanthomonas fragariae in strawberry. A screening procedure based on in vitro and in planta assays of the three bacterial pathogens was successful in selecting potential LAB strains as biological control agents. The antagonistic activity of 55 strains was first tested in vitro and the strains Lactobacillus plantarum CC100, PM411 and TC92, and Leuconostoc mesenteroides CM160 and CM209 were selected because of their broad-spectrum activity. The biocontrol efficacy of the selected strains was assessed using a multiple-pathosystem approach in greenhouse conditions. L. plantarum PM411 and TC92 prevented all three pathogens from infecting their corresponding plant hosts. In addition, the biocontrol performance of PM411 and TC92 was comparable to the reference products (Bacillus amyloliquefaciens D747, Bacillus subtilis QST713, chitosan, acibenzolar-S-methyl, copper and kasugamycin) in semi-field and field experiments. The in vitro inhibitory mechanism of PM411 and TC92 is based, at least in part, on a pH lowering effect and the production of lactic acid. Moreover, both strains showed similar survival rates on leaf surfaces. PM411 and TC92 can easily be distinguished because of their different multilocus sequence typing and random amplified polymorphic DNA profiles ; Funding was provided by AGL2015‐69876‐C2‐1‐R (Spain Ministerio de Economía y Competitividad and FEDER of the European Union), by FP7‐KBBE.2013.1.2‐04 613678 DROPSA of the European Union, and by the MPCUdG2016 grant (University of Girona). N. Daranas was recipient of the research grant 2015 FI_B00515 (Secretaria d'Universitats i Recerca, Departament d'Economia i Coneixement, Generalitat de Catalunya; ES, EU). The research group is accredited by SGR 2014‐697 and TECNIO net from the Department d'Economia i Coneixement‐ACCIÓ Catalonia

El objetivo de esta investigación cuantitativa es construir el Juego Digital para el proceso enseñanza-aprendizaje sobre la Electrónica (JDE) versión 2.0 y analizar el impacto de esta herramienta tecnológica en el curso Diseño Digital durante la pandemia COVID-19. Este trabajo fue realizado con el apoyo del Programa UNAM-DGAPA-PAPIME con clave PE400421. Los resultados indican que el simulador del juego digital JDE influye positivamente en la asimilación del conocimiento en el campo de la electrónica, el desarrollo de habilidades para el campo de la electrónica y el aprendizaje desde cualquier lugar. En particular, el juego digital JDE versión 2.0 es una alternativa tecnológica que favorece el proceso enseñanza-aprendizaje en el campo de la electrónica.

The nature and size of the real active species of nanoparticulated metal supported catalysts is still an unresolved question. The technique of choice to measure particle sizes at the nanoscale, HRTEM, has a practical limit of 1 nm. This work is aimed to identify the catalytic role of subnanometer species and methods to detect and characterize them. In this frame, we investigated the sensitivity to redox pretreatments of Ag/Fe/TiO 2 , Ag/Mg/TiO 2 and Ag/Ce/TiO 2 catalysts in CO oxidation. The joint application of HRTEM, SR-XRD, DRS, XPS, EXAFS and XANES methods indicated that most of the silver in all samples is in the form of Ag species with size <1 nm. The differences in catalytic properties and sensitivity to pretreatments, observed for the studied Ag catalysts, could not be explained taking into account only the Ag particles whose size distribution is measured by HRTEM, but may be explained by the presence of the subnanometer Ag species, undetectable by HRTEM, and their interaction with supports. This result highlights their role as active species and the need to take them into account to understand integrally the catalysis by supported nanometals. ; We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI). ; This research was supported by Government Program "Science" of Tomsk Polytechnic University, Grant No. 4.1187.2014/K, CONACYT Project 260409 and PAPIIT-UNAM Project IT200114 (Mexico), CSIC project 201480E077 and MINECO Project CTQ2013-41507-R (Spain). We gratefully thank O. Martynyuk, G. Torres Otañez, Z. I. Bedolla Valdez, E. Flores, F. Ruiz Medina, A. Olivas Sarabia, I. Gradilla, J. Mendoza, E. M. Aparicio Ceja, J. Peralta, David A. Domínguez, M. Sainz, R. Valdez Castro, M. Martínez, B. Acosta Ruelas, F. Ramírez Hernández and M. López Cisneros for valuable technical assistance.