Magnetic Properties of a-Si films doped with rare-earth elements

Amorphous silicon films doped with Y, La, Gd, Er, and Lu rare-earth elements (a-Si:RE) have been prepared by co-sputtering and studied by means of electron spin resonance (ESR), dc-magnetization, ion beam analysis, optical transmission, and Raman spectroscopy. For comparison the magnetic properties of laser-crystallized and hydrogenated a-Si:RE films were also studied. It was found that the rare-earth species are incorporated in the a-Si:RE films in the RE3+ form and that the RE-doping depletes the neutral dangling bonds (D0) density. The reduction of D0 density is significantly larger for the magnetic REs (Gd3+ and Er3+) than for the non-magnetic ones (Y3+, La3+, Lu3+). These results are interpreted in terms of a strong exchange-like interaction, J RE-DB SRE SDB, between the spin of the magnetic REs and that of the D0. All our Gd-doped Si films showed basically the same broad ESR Gd3+ resonance (DHpp ~ 850 Oe) at g ~ 2.01, suggesting the formation of a rather stable RE-Si complex in these films.Comment: 15 pages, 7 figure

Understanding YouTube Culture and How It Affects Today\u27s Media

The rise and growth of YouTube has created some of the biggest social media and marketing entrepreneurs and has enabled its audience to navigate the platform to their liking. Because of the business franchise YouTube has become a catalyst for famous YouTube creators, regular people with a dream to make it in the “Hollywood Industry.” YouTube provided the resources to these stars, so they would could share their content and be given the opportunity to partner with other Public Relations and Marketing teams for other businesses

Soil organic matter regulating greenhouse gases in tropical and subtropical environments: a comparison between integrated crop-livestock and annual cropping systems.

Carbon and nitrogen cycles in grassland, annual cropping and integrated crop-livestock (ICL) systems control soil quality and regulate greenhouse gas emissions. The aim of this study was to review the knowledge on driving factors controlling soil organic carbon (OC) accumulation and greenhouse gas emissions in tropical and subtropical Brazilian ecosystems under ICL and annual cropping systems. The ICL system has a significant potential to promote soil OC sequestration, mainly due to biomass addition but also because stabilization by physical protection and organo-mineral associations. The soil OC accumulation in ICL, compared to annual cropping, can extend up to 100 cm depth. In general, emission of nitrous oxide (N2O) from soil is higher in ICL than in annual cropping, although the opposite may also occur. The N2O emission in ICL, however, can be offset by soil OC accumulation, although not always. Strategies to further increase soil OC sequestration and curb N2O emissions must be developed for ICL, which is a system that is being encouraged in Brazil because of the many ecosystem services and economical benefits that it provides

Synchrotron radiation reveals the identity of the large felid from Monte Argentario (Early Pleistocene, Italy)

We describe here a partial skull with associated mandible of a large felid from Monte Argentario, Italy (Early Pleistocene; ~1.5 million years). Propagation x-ray phase-contrast synchrotron microtomography of the specimen, still partially embedded in the rock matrix, allows ascribing it reliably to Acinonyx pardinensis, one of the most intriguing extinct carnivorans of the Old World Plio-Pleistocene. The analysis of images and 3D models obtained through synchrotron microtomography – here applied for the first time on a Plio-Pleistocene carnivoran – reveals a mosaic of cheetah-like and Panthera-like features, with the latter justifying previous attributions of the fossil to the extinct Eurasian jaguar Panthera gombaszoegensis. Similarly, we reassign to A. pardinensis some other Italian materials previously referred to P. gombaszoegensis (sites of Pietrafitta and Ellera di Corciano). The recognition of Panthera-like characters in A. pardinensis leads to reconsidering the ecological role of this species, whose hunting strategy was likely to be different from those of the living cheetah. Furthermore, we hypothesise that the high intraspecific variation in body size in A. pardinensis can be the result of sexual dimorphism, as observed today in all large-sized felids

Ergodicity breaking in strong and network-forming glassy system

The temperature dependence of the non-ergodicity factor of vitreous GeO$_2$, $f_{q}(T)$, as deduced from elastic and quasi-elastic neutron scattering experiments, is analyzed. The data are collected in a wide range of temperatures from the glassy phase, up to the glass transition temperature, and well above into the undercooled liquid state. Notwithstanding the investigated system is classified as prototype of strong glass, it is found that the temperature- and the $q$-behavior of $f_{q}(T)$ follow some of the predictions of Mode Coupling Theory. The experimental data support the hypothesis of the existence of an ergodic to non-ergodic transition occurring also in network forming glassy systems

Efeito de raízes e cobertura morta de B. ruziziensis na matéria orgânica e na agregação de um latossolo vermelho distroférrico.

Avaliaram-se efeitos da Brachiaria ruziziensis em atributos de um Latossolo Vermelho distroférrico, em casa de vegetação. Noventa dias após a emergência das plantas instalaram-se os tratamentos: a) Corte e remoção da parte aérea; b) Corte e retorno da parte aérea, sem fragmentação, para a superfície do solo; c) Corte e retorno da parte aérea fragmentada; d) Cobertura do solo com 7,5 Mg ha-1 (massa seca) de material da parte aérea não fragmentada; e) Idem ao d) com material fragmentado; f) Corte à 40 cm de altura e retorno do material sem fragmentação; g) Idem ao f) com remoção da parte aérea; h) Corte à 20 cm e exclusão da parte aérea; e i) Testemunha. Determinaram-se: massa seca da parte aérea e resíduos; e, após um ano, o carbono orgânico das camadas 0-5, 5-10 e 10-20 cm e a agregação do solo da camada 0?10 cm. O delineamento foi o inteiramente casualizado, com quatro repetições; as médias foram comparadas por teste de Tukey (p 4,76 mm, dos primeiros 10 cm do solo