Rhizobia are soil proteobacteria able to establish a nitrogen-fixing interaction with legumes. In this interaction, rhizobia must colonize legume roots, infect them, and become hosted inside new ...organs formed by the plants and called nodules. Rhizobial motility, not being essential for symbiosis, might affect the degree of success of the interaction with legumes. Because of this, the study of rhizobial motility (either swimming or surface motility) might be of interest for research teams working on rhizobial symbiotic performance. In this chapter, we describe the protocols we use in our laboratories for studying the different types of motilities exhibited by Sinorhizobium fredii and Sinorhizobium meliloti, as well as for analyzing the presence of flagella in these bacteria. All these protocols might be used (or adapted) for studying bacterial motility in rhizobia.
Chile, isolated by a hyper-arid desert in the north, the Andes Range to the east and the Pacific and Antarctic waters (west and south), has a highly endemic flora. This hotspot of biodiversity is in ...danger not only due to increasing desertification, but also because human activities can diminish agrobiodiversity. Quinoa (Chenopodium quinoa Willd.) is an Andean species producing highly nutritious grains, which almost disappeared from Chile during the Spanish colonization. Today less than 300 small-scale and highly isolated farmers still grow it as a rain-fed crop. This review describes the biogeographical-social context of quinoa in Chile, and its high genetic diversity as a product of a long domestication process, resulting in numerous local landraces whose conservation and use for breeding improved varieties is of paramount importance. We suggest the term "lighthouse crop" to emphasize its contribution to small scale ecological and bio diverse agriculture, particularly in stressful environments, to promote a healthier nutrition and more equitable markets in the world. Furthermore this crop and its exceptional nutritional properties were invoked by the United Nations Food and Agriculture Organization (FAO) to promote its use worldwide, and to declare 2013 the International Year of Quinoa.
Nowadays, information technology opens great opportunities to transform teaching and learning. Currently, different platforms have been deployed to offer teaching services. These platforms can be ...built from computer systems that collect and analyze data, to those systems that interact with users and allow them to learn from these data. For example, a system can build animations to visualize and understand the operation of an industrial process or an algorithm. This paper presents a digital tool to support the teaching and learning of quality of service (QoS) algorithms in the communication networks. Quality of service is an important topic in the computers networks courses due to the current high demand for quality multimedia content on the internet. Our digital teaching tool tries to support the teaching/learning processes in this important communication networks topic.
Una opción para incrementar el valor de las maderas de baja densidad puede ser el combinarlas con especies de densidades más altas. A los productos que combinan madera de diferentes propiedades se ...les conoce como productos de ingeniería. El presente trabajo tuvo como objetivo diseñar, producir y evaluar, a través de sus propiedades físicomecánicas, un piso de ingeniería de 16 mm de espesor. Este producto se conformó de tres capas, utilizando palma de coco (Cocos nucifera) o melina (Gmelina arborea) como sustrato y encino rojo (Quercus castanea) como refuerzo. Se ensayaron tres tipos de adhesivos: urea formaldehido, henkel loctite y soya furfural. Con los dos sustratos utilizados, se obtuvo una densidad normal promedio de 0.53 g cm-3 a un contenido de humedad promedio de 9%. La resistencia a la flexión fluctuó entre 12 MPa y 62 MPa y el módulo de elasticidad entre 1346 MPa y 10 660 MPa. La combinación de encino-melina-encino con urea formaldehido fue la que presentó los mejores resultados. La dureza Brinell exhibió valores de 30 N mm-2 a 48 N mm-2 y la combinación encino-palma-encino con loctite fue la que arrojó el mayor valor. La resistencia al cortante de la línea de encolado fue de 0.11 MPa a 3.46 MPa. Las combinaciones encino-palma-encino soya furfural, encino-palma-encino urea formaldehido, así como encino-melina-encino urea formaldehido no presentaron diferencias estadísticas significativas en la resistencia de la línea adhesiva. Los pisos con urea formaldehido y con soya furfural fueron susceptibles a la delaminación al contacto directo con el agua y ante cambios de humedad relativa en el ambiente de 35% y 55%.
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