16,386 research outputs found
Curved Graphene Nanoribbons: Structure and Dynamics of Carbon Nanobelts
Carbon nanoribbons (CNRs) are graphene (planar) structures with large aspect
ratio. Carbon nanobelts (CNBs) are small graphene nanoribbons rolled up into
spiral-like structures, i. e., carbon nanoscrolls (CNSs) with large aspect
ratio. In this work we investigated the energetics and dynamical aspects of
CNBs formed from rolling up CNRs. We have carried out molecular dynamics
simulations using reactive empirical bond-order potentials. Our results show
that similarly to CNSs, CNBs formation is dominated by two major energy
contribution, the increase in the elastic energy due to the bending of the
initial planar configuration (decreasing structural stability) and the
energetic gain due to van der Waals interactions of the overlapping surface of
the rolled layers (increasing structural stability). Beyond a critical diameter
value these scrolled structures can be even more stable (in terms of energy)
than their equivalent planar configurations. In contrast to CNSs that require
energy assisted processes (sonication, chemical reactions, etc.) to be formed,
CNBs can be spontaneously formed from low temperature driven processes. Long
CNBs (length of 30.0 nm) tend to exhibit self-folded racket-like
conformations with formation dynamics very similar to the one observed for long
carbon nanotubes. Shorter CNBs will be more likely to form perfect scrolled
structures. Possible synthetic routes to fabricate CNBs from graphene membranes
are also addressed
Tipos nomenclaturais de plantas vasculares depositados no herbário IAN da Embrapa Amazônia Oriental - Aristolochiaceae Adans.; Asclepiadaceae Borkh.; Bombacaceae Kunth; Lecythidaceae A. Rich., Meliaceae Juss. e Moraceae Link.
Shades of red and blue: Political ideology and sustainable development
We study the effect of political ideology on sustainable development, measured as investment in genuine wealth, in a dynamic panel of 79 countries between 1981 and 2013. We find that a switch from a left-wing or centrist government to a right-wing government has a robust positive and statistically significant effect on investment in genuine wealth. We find no evidence of opportunistic cycles in these investments
Levantamento, informatização, classificação e divulgação dos tipos nomenclaturais do Herbário IAN (Embrapa Amazônia Oriental).
Tipos nomenclaturais das famílias Dichapetalaceae e Droseraceae depositados no Herbário IAN da Embrapa Amazônia Oriental, Belém, Pará, Brasil.
Levantamento, informatização, classificação e divulgação dos tipos nomenclaturais de Dilleniaceae Salisb. do Herbário IAN da Embrapa Amazônia Oriental.
Tipos nomenclaturais de Crhysobalanaceae depositados no acervo de Herbário IAN (Embrapa Amazônia Oriental) - Belém, PA, Brasil.
Levantamento, informatização e caracterização dos tipos nomenclaturais de Malpighiaceae juss. existentes no herbário IAN - Embrapa Amazônia Oriental.
Aplicação da PCAM e da análise de agrupamento em clones de cupuaçuzeiro.
O objetivo deste trabalho foi estudar a divergência genética de 50 clones de cupuaçuzeiro, por meio da PCAM e da Análise de Agrupament
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