Surface nano-patterning through styrene adsorption on Si(100)

We present an ab initio study of the structural and electronic properties of styrene molecules adsorbed on the dimerized Si(100) surface at different coverages, ranging from the single-molecule to the full monolayer. The adsorption mechanism primarily involves the vinyl group via a [2+2] cycloaddition process that leads to the formation of covalent Si-C bonds and a local surface derelaxation, while it leaves the phenyl group almost unperturbed. The investigation of the functionalized surface as a function of the coverage (e.g. 0.5 -- 1 ML) and of the substrate reconstruction reveals two major effects. The first results from Si dimer-vinyl interaction and concerns the controlled variation of the energy bandgap of the interface. The second is associated to phenyl-phenyl interactions, which gives rise to a regular pattern of electronic wires at surface, stemming from the pi-pi coupling. These findings suggest a rationale for tailoring the surface nano-patterning of the surface, in a controlled way.Comment: 19 pages (preprint), 4 figures, supplementary materia

Phase Transition in Asymmetrical Superfluids I: Equal Fermi Surfaces

In this paper, we study phase transitions in asymmetrical fermion superfluids. In this scenario, the candidates to form pair are particles with mismatched masses and chemical potentials. We derive an expression for the critical temperature in terms of the gap and masses (or chemical potentials) when the constraint of equal Fermi surfaces $m_a\mu_a = m_b\mu_b$ is imposed.Comment: RevTex, 11 pages, 2 figures, typos corrected and an appendix added, accepted for publication in Phys. Rev.

Caracterização dos agroecossistemas e manejo de germoplasma de Citrullus em três regiões do Nordeste brasileiro.

Sendo assim, este trabalho teve como objetivos caracterizar, estudar e descrever os agroecossistemas nordestinos representados pelos distritos de Jamarí-MA, Massaroca-BA e Urimamã-PE

Qualidade de grãos de arroz irrigado influenciada pelo manejo de nitrogênio baseado no uso do clorofilômetro.

O objetivo do estudo foi avaliar a influência de doses de N em cobertura baseadas no uso do clorofilômetro sobre qualidade dos grãos da cultivar BRS Tropical de arroz irrigado

Doses de nitrogênio na qualidade de grãos de arroz irrigado.

Objetivou-se com esse estudo avaliar a influência de doses de N em cobertura sobre a qualidade dos grãos da cultivar BRS Tropical de arroz irrigado