On the thermal stability of the nanostructured tungsten coatings

Tungsten is a candidate to be used as plasma facing materials in future fusion nuclear reactors. There, the material has to withstand large radiation fluxes and thermal loads. Nowadays, nanostructured tungsten (NW) seems to exhibit a better radiation-resistance than the coarse grained. However, the thermal stability of NW is still an open question. On these bases, the thermal stability of NW coatings is studied in the temperature range from 1000 to 1473 K. For this purpose, Samples were isothermally annealed in vacuum at temperatures from 298 to 1473 K. The morphological and microstructural properties of the samples were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-Ray diffraction (XRD), respectively. For T 100 K, nanostructures start to grow in a bimodal fashion with activation energy of 0259 eV, reaching a submicron-sized threshold at T approximate to 1473 K

Using multimedia and peer assessment to promote collaborative e-learning

Collaborative e-learning is increasingly appealing as a pedagogical approach that can positively affect student learning. We propose a didactical model that integrates multimedia with collaborative tools and peer assessment to foster collaborative e-learning. In this paper, we explain it and present the results of its application to the “International Seminars on Materials Science” online course. The proposed didactical model consists of five educational activities. In the first three, students review the multimedia resources proposed by the teacher in collaboration with their classmates. Then, in the last two activities, they create their own multimedia resources and assess those created by their classmates. These activities foster communication and collaboration among students and their ability to use and create multimedia resources. Our purpose is to encourage the creativity, motivation, and dynamism of the learning process for both teachers and students