Raman-scattering study of the phonon dispersion in twisted bi-layer graphene

Bi-layer graphene with a twist angle \theta\ between the layers generates a superlattice structure known as Moir\'{e} pattern. This superlattice provides a \theta-dependent q wavevector that activates phonons in the interior of the Brillouin zone. Here we show that this superlattice-induced Raman scattering can be used to probe the phonon dispersion in twisted bi-layer graphene (tBLG). The effect reported here is different from the broadly studied double-resonance in graphene-related materials in many aspects, and despite the absence of stacking order in tBLG, layer breathing vibrations (namely ZO' phonons) are observed.Comment: 18 pages, 4 figures, research articl

Princípios cooperativistas e cooperativismo de crédito: Um estudo de caso em Paraíso do Tocantins, Brasil.

O objetivo foi identificar a prática dos princípios cooperativas em uma cooperativa de crédito na percepção dos dirigentes, além de observar se as metas traçadas pelos dirigentes seguem a linha dos princípios cooperativistas. A pesquisa é exploratória de caráter qualitativo e tendo como metodologia o estudo de caso, com o apoio da técnica entrevista semi-estruturada. Entre os resultados, notou-se que a cooperativa segue parcialmente os princípios do cooperativismo, identificou-se que a comunicação está deficiente e é um ponto que deve ser fortalecido, o que facilitaria o desenvolvimento da cooperativa

Comparison of a retrotransposon-based marker with microsatellite markers for discriminating accessions of Vitis vinifera.

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Quantifying defects in graphene via Raman spectroscopy at different excitation energies.

We present a Raman study of Ar(+)-bombarded graphene samples with increasing ion doses. This allows us to have a controlled, increasing, amount of defects. We find that the ratio between the D and G peak intensities, for a given defect density, strongly depends on the laser excitation energy. We quantify this effect and present a simple equation for the determination of the point defect density in graphene via Raman spectroscopy for any visible excitation energy. We note that, for all excitations, the D to G intensity ratio reaches a maximum for an interdefect distance ∼3 nm. Thus, a given ratio could correspond to two different defect densities, above or below the maximum. The analysis of the G peak width and its dispersion with excitation energy solves this ambiguity

Selection efficiency in Brachiaria hybrids using a posteriori blocking.

This paper compares the efficiency of Brachiaria hybrid clone selection by either traditional analysis or a posteriori blocking, to adequately consider the effect oflower competition in the border rows ofthe experimental plots (border effect). Results demonstrated that a posteriori blocking improved selection and the reliability ofthe genotypic evaluation. Of the ten best clones. four did not coincide in the two approaches. The ranking was altered as well, which demonstrated that the indication of the five best clones. selected to proceed to pasture trials based on the traditional evaluation, was misleading. This paper confirms the usefulness of a posteriori blocking. Furthermore, the results revealed lhe need to impose more effective competition on plants in the border rows to avoid erroneous selection when conducting evaluations for agronomic performance in Brachiaria trials

Detecting somaclonal variation during micropropagation of vine rootstocks using SSR molecular marker and flow cytometery analysis.

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Optical-phonon resonances with saddle-point excitons in twisted-bilayer graphene

Twisted-bilayer graphene (tBLG) exhibits van Hove singularities in the density of states that can be tuned by changing the twisting angle $\theta$. A $\theta$-defined tBLG has been produced and characterized with optical reflectivity and resonance Raman scattering. The $\theta$-engineered optical response is shown to be consistent with persistent saddle-point excitons. Separate resonances with Stokes and anti-Stokes Raman scattering components can be achieved due to the sharpness of the two-dimensional saddle-point excitons, similar to what has been previously observed for one-dimensional carbon nanotubes. The excitation power dependence for the Stokes and anti-Stokes emissions indicate that the two processes are correlated and that they share the same phonon.Comment: 5 pages, 6 figure

Tutorial para instalação e utilização da Rede Blockchain Ethereum no Ubuntu Linux.

O objetivo deste trabalho é apresentar a implementação de um contrato inteligente em uma rede privada Ethereum Blockchain, de forma a tornar possível o uso desta rede nos mais diversos tipos de aplicação, principalmente nos casos de rastreabilidade; neste caso, foi escolhido como exemplo a possibilidade de rastreamento de caixas de manga.bitstream/item/205983/1/Documentos162.pd