Influence of 4f filling on electronic and magnetic properties of rare earth-Au surface compounds

Altres ajuts: This work was supported in part by the Basque Government Project IT-1255-19, and University of the Basque Country (UPV/EHU) grant GIU18/138 and the European Regional Development Fund (ERDF) under the program Interreg V-A España-Francia-Andorra (Contract No. EFA 194/16 TNSI).One-atom-thick rare-earth/noble metal (RE-NM) compounds are attractive materials to investigate two-dimensional magnetism, since they are easy to synthesize into a common RE-NM2 structure with high crystal perfection. Here we perform a comparative study of the GdAu2, HoAu2, and YbAu2 monolayer compounds grown on Au(111). We find the same atomic lattice quality and moiré superlattice periodicity in the three cases, but different electronic properties and magnetism. The YbAu2 monolayer reveals the characteristic electronic signatures of a mixed-valence configuration in the Yb atom. In contrast, GdAu2 and HoAu2 show the trivalent character of the rare-earth and ferromagnetic transitions below 22 K. Yet, the GdAu2 monolayer has an in-plane magnetic easy-axis, versus the out-of-plane one in HoAu2. The electronic bands of the two trivalent compounds are very similar, while the divalent YbAu2 monolayer exhibits different band features. In the latter, a strong 4f-5d hybridization is manifested in neatly resolved avoided crossings near the Fermi level. First principles theory points to a residual presence of empty 4f states, explaining the fluctuating valence of Yb in the YbAu2 monolayer

Uso de eugenol como anestésico para três espécies de acaris ornamentais amazônicos.

O uso de anestésico visando a diminuição do estresse ocasionado na manipulação dos peixes é uma alternativa para melhorar produtividade de peixes ornamentais assim como está dentro dos preceitos de bem estar animal. Portanto, o presente estudo avaliou os tempos de indução e recuperação do Hypancistrus zebra, Ancistrus ranunculus e Baryancistrus xanthellus submetido a anestesia por eugenol. Para tanto, foram utilizados 30 exemplares de H. zebra, A. ranunculus e B. xanthellus em um delineamento inteiramente casualizado com seis concentrações de eugenol (40, 60, 80, 100, 120 e 140 mg.L-1) e cinco repetições. O H. zebra apresentou maior sensibilidade a anestesia por eugenol apresentando menor tempo de indução (7,9 ± 5,19s) entre as espécies, o contrario foi observado para A. ranunculus. Já para o período de recuperação, o H. zebra e A. ranunculus apresentaram os menores tempo (p<0,05) na concentração de 40 mg.L-1, não sendo observado diferença no tempo de recuperação para o B. xanthellus. Assim, para o H. zebra recomenda-se a concentração de 120 mg.L-1 e para A. Ranunculus e B. xanthellus a concentração de 140 mg.L-1, visando o menor tempo de indução para minimizar o estresse no manejo desses animais. Porém, outros estudos devem ser realizados para comprovar a seguridade de uso sem efeitos colateraisparaos peixes nessas concentrações

Analysing interactions in a teacher network forum: a sociometric approach

This article presents the sociometric analysis of the interactions in a forum of a social network created for the professional development of Portuguese-speaking teachers. The main goal of the forum, which was titled Stricto Sensu, was to discuss the educational value of programmes that joined the distance learning model in Brazil. The empirical study focused on the sociometrie analysis of the social interactions that take place in asynchronous online environments. This approach, according to literature, allows for new means to observe, analyse, and interpret the reality of a new social paradigm. This type of analysis tries to understand the relationship established between the different actors, seeking to verify if the roles they play in both the access to information and the construction of shared knowledge. The data collected allow the researchers to deduce that the indicators used in the analysis are important for understanding and intervening in the dynamics and functioning of the network to propose improvements in its structure and organisation. In the specific case of the aforementioned discussion forum, the results of the sociometrie analysis of the perceived interactions were not surprising, considering that the nature of the topic did not demand deep reflection to contribute to the debate.This work is funded by Portuguese Foundation for Science and Technology under the doctoral grant SFRH/BD/60677/2009

Ten years of Ana: lessons from a transdisciplinary body of literature on online pro-eating disorder websites

This paper offers a methodical review of the scientific literature of the last decade that concerns itself with online services offering supportive advocacy for anorexia nervosa and bulimia nervosa (‘pro-ana’ and ‘pro-mia’). The main question is whether these studies reproduce the traditional divide in the study of eating disorders, between clinical and social science perspectives, with limited mutual exchanges. Having first identified a specific body of literature, the authors investigate its content, methods and approaches, and analyse the network of cross-citations the components generate and share. On this basis, the authors argue that the scientific literature touching on pro-ana websites can be regarded as a single transdisciplinary body of knowledge. What’s more, they show that the literature on computermediated sociabilities centred on eating disorders displays different structural characteristics with respect to the traditional, non-Web-related research on eating disorders. In the latter, the social sciences have usually provided a critical counterpoint to the development of a health sciences mainstream. In the case of Web-related research, however, the social sciences have taken the lead role in defining the field, with the health sciences following suit