Electronic doping of graphene by deposited transition metal atoms

We perform a phenomenological analysis of the problem of the electronic doping of a graphene sheet by deposited transition metal atoms, which aggregate in clusters. The sample is placed in a capacitor device such that the electronic doping of graphene can be varied by the application of a gate voltage and such that transport measurements can be performed via the application of a (much smaller) voltage along the graphene sample, as reported in the work of Pi et al. [Phys. Rev. B 80, 075406 (2009)]. The analysis allows us to explain the thermodynamic properties of the device, such as the level of doping of graphene and the ionisation potential of the metal clusters in terms of the chemical interaction between graphene and the clusters. We are also able, by modelling the metallic clusters as perfect conducting spheres, to determine the scattering potential due to these clusters on the electronic carriers of graphene and hence the contribution of these clusters to the resistivity of the sample. The model presented is able to explain the measurements performed by Pi et al. on Pt-covered graphene samples at the lowest metallic coverages measured and we also present a theoretical argument based on the above model that explains why significant deviations from such a theory are observed at higher levels of coverage.Comment: 16 pages, 10 figure

Tetranychus bastosi Tuttle, Baker & Sales (Prostigmata: Tetranychidae) mites on Jatropha curcas (Linaeus) in Sergipe State, Brazil.

Os ácaros tetraniquídeos representam importantes pragas para diversas culturas agrícolas por todo o mundo. Durante a prospecção de germoplasma de pinhão manso, Jatropha curcas L. no Estado de Sergipe, Brasil. A ocorrência destes foi observada em algumas plantas menos vigorosas e que apresentavam sintomas de redução e encarquilhamento do limbo. Foram coletados 100 indivíduos destas plantas os quais foram montados em lâminas de microscopia para a identificação taxonômica. Os ácaros foram identificados como pertencentes à espécie Tetranychus bastosi (Acari: Tetranychidae). Este é o primeiro relato em pinhão manso, J. curcas, como hospedeira para T. bastosi no Brasil

Ervilha forrageira como adubo verde para trigo: resultados preliminares.

bitstream/CNPT-2010/40504/1/p-co139.pd

Impacto de espécies de inverno no rendimento de grãos de culturas de verão e de trigo no inverno subseqüente.

bitstream/CNPT-2010/40292/1/p-bp19.pd

Diagnóstico ambiental do município de Santana do Ipanema, Alagoas.

bitstream/CNPS-2010/14878/1/bpd76-2005-santana-ipanema.pd

Tutoramento de plantas de ervilha visando à produção de grãos secos.

bitstream/CNPT-2010/40286/1/p-bp13.pd

Tecnologia para produção de canola no Rio Grande do Sul.

bitstream/CNPT-2010/40772/1/p-do113.pd

Evaluation of brazilian dairy goat breeding programs.

Abstract: This work aimed to evaluate the genetic and economic gains for two selection schemes for dairy goats in Brazil. Analyses were performed by ZPLAN software. The traditional scheme had no economic viability, except with high levels (>=60%) of using nucleus bucks on commercial flocks. However, this has no practical feasibility due the low use of artificial insemination in Brazil. The progeny testing of young bucks presented viability, with considerable genetic gains for the selection objective and the individual traits that make up this goal. The economic returns of the program outweighed its costs, with an investment return of 20 %. In this scheme, the trait of greater economic impact was milk yield followed by somatic cell count. The amount of using of young bucks should be up to 15 % since higher levels reduce the economic efficiency of the program

Conservation of Orbital Angular Momentum in Stimulated Down-Conversion

We report on an experiment demonstrating the conservation of orbital angular momentum in stimulated down-conversion. The orbital angular momentum is not transferred to the individual beams of the spontaneous down-conversion, but it is conserved when twin photons are taken individually. We observe the conservation law for an individual beam of the down-conversion through cavity-free stimulated emission.Comment: Submitted for publication in Phys. Rev. Let