Catching the Bound States in the Continuum of a Phantom Atom in Graphene

We explore theoretically the formation of bound states in the continuum (BICs) in graphene hosting two collinear adatoms situated at different sides of the sheet and at the center of the hexagonal cell, where a phantom atom of a fictitious lattice emulates the six carbons of the cell. We verify that in this configuration the local density of states (LDOS) near the Dirac points exhibits two characteristic features: i) the cubic dependence on energy instead of the linear one for graphene as found in New J. Phys. 16, 013045 (2014) and ii) formation of BICs as aftermath of a Fano destructive interference assisted by the Coulomb correlations in the adatoms. For the geometry where adatoms are collinear to carbon atoms, we report absence of BICs

Quantum phase transition triggering magnetic BICs in graphene

Graphene hosting a pair of collinear adatoms in the phantom atom configuration has pseudogap with cubic scaling on energy, $\Delta\propto|\varepsilon|^{3}$ which leads to the appearance of spin-degenerate bound states in the continuum (BICs) [Phys. Rev. B 92, 045409 (2015)]. In the case when adatoms are locally coupled to a single carbon atom the pseudogap scales linearly with energy, which prevents the formation of BICs. In this Letter, we explore the effects of non-local coupling characterized by the Fano factor of interference $q_{0},$ tunable by changing the slope of the Dirac cones in the graphene band-structure. We demonstrate that three distinct regimes can be identified: i) for $q_{0}<q_{c1}$ (critical point) a mixed pseudogap $\Delta\propto|\varepsilon|,|\varepsilon|^{2}$ appears yielding a phase with spin-degenerate BICs; ii) near $q_{0}=q_{c1}$ when $\Delta\propto|\varepsilon|^{2}$ the system undergoes a quantum phase transition in which the new phase is characterized by magnetic BICs and iii) at a second critical value $q_{0}>q_{c2}$ the cubic scaling of the pseudogap with energy $\Delta\propto|\varepsilon|^{3}$ characteristic to the phantom atom configuration is restored and the phase with non-magnetic BICs is recovered. The phase with magnetic BICs can be described in terms of an effective intrinsic exchange field of ferromagnetic nature between the adatoms mediated by graphene monolayer. We thus propose a new type of quantum phase transition resulting from the competition between the states characterized by spin-degenerate and magnetic BICs

Pastoreio de aveia e compactação do solo.

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Fracionamento de substâncias húmicas do solo por cromatografia de exclusão em coluna.

Representacao esquematica do principio da exclusao; moleculas grandes (MG) somente se movem externamente ao granulo ou matriz cromatografica (volume morto = Vo), ao passo que moleculas pequenas (Mp) podem se mover tambem por dentro dos granulos (volume interno = Vi); Vp indica volume ocupado pelos granulos; Cromatografia em granulos porosos de vidro (Controlled-Pore Glass); Cromatografia em granulos porosos de vidro de substancias humicas de um Latossolo Roxo de Londrina, PR; Cromatogramas dos extratos de substancias humicas de um Latossolo Vermelho distroferrico de Londrina, PR; Teores totais de substancias humicas extraidas (d.o. = densidade otica do extrato total a 400 nm) de um Latossolo Vermelho eutroferrico de Londrina, PR; A se refere ao solo sob floresta secundaria; B se refere ao solo sob plantio direto e C se refere ao solo sob plantio convencional (uma aracao seguida de duas gradagens leves niveladoras); Medida da distribuicao do peso molecular (E1/E2%) das substancias humicas de um Latossolo Vermelho eutroferrico de Londrina, PR; Cromatogramas de substancias humicas e teor de aluminio associado de Latossolo Vermelho eutroferrico (A) sob floresta de eucalipto (Al troc = 12 mmolc.kg-1; C org = 50,0 g.kg-1; teor de argila = 700 g.kg-1) e de Latossolo Vermelho distrofico (B) sob floresta de Pinus sp. (Al troc = 19 mmolc.kg-1; C org = 7 g.kg-1; teor de argila = 130 g.kg-1).bitstream/item/62213/1/Fracionamento-de-substancias.pd

Especies de Mycosphaerella y Teratosphaeria asociadas con la enfermedad Mycosphaerella de las hojas en Eucalyptus globulus en Portugal

Plantations of Eucalyptus globulus represent the main source of wood for the pulp and paper industry in Portugal and are affected by the complex of Mycosphaerella and Teratosphaeria species (Mycosphaerella leaf disease), which is an important foliage disease worldwide. This disease affect mainly young trees with juvenile-phase foliage, causing premature defoliation, decreased growth and wood production. Species of Mycosphaerella sensu lato reported on eucalypts in Portugal are M. communis, M. heimii, M. lateralis, M. madeirae, M. marksii M. walkeri, T. africana, T. molleriana, T. nubilosa and T. parva. In order to complete the survey, symptomatic leaves were collected from Eucalyptus globulus plantations. Morphological and molecular characterization was used to give an indication of the species occurrence and most frequent species (T. nubilosa) and the composition of the MLD complex that did not change after the latest review.Las plantaciones de Eucalyptus globulus representan la principal fuente de madera para la industria de pasta y papel en Portugal y se ven afectadas por el complejo de especies de Mycosphaerella y Teratosphaeria (enfermedad Mycosphaerella de las hojas), que es una enfermedad importante en todo el mundo. Esta enfermedad afecta principalmente a los árboles con fase juvenil de follaje, causando defoliación prematura, disminución del crecimiento y de producción de madera. Las especies de Mycosphaerella sensu lato descritas sobre el eucalipto en Portugal son M. communis, M. heimii, M. lateral, M. madeirae, M. marksii, M walkeri, T. africana, T. molleriana, T. nubilosa y T. parva. Con el fin de completar el inventario, se obtuvieron hojas sintomáticas de plantaciones de Eucalyptus globulus. Se ha utilizado una caracterización morfológica y molecular para identificar la presencia de especies, la especie más frecuente (T. nubilosa) y la composición del complejo de MLD que no cambió después de esta última revisión

Diversidade genética entre acessos de maracujazeiros avaliados a partir de caracteres morfoagronômicos.

A análise conjunta de variáveis qualitativas e quantitativas tem sido apontada como uma ferramenta útil na estimativa da divergência genética entre os acessos de uma coleção de germoplasma. O presente trabalho teve como objetivo quantificar a diversidade genética entre acessos de maracujazeiros mantidos no BAG-Maracujá da Embrapa Mandioca e Fruticultura, utilizando uma lista de descritores mínimos para a cultura

Antocianinas nas folhas vermelhas de Euphorbia pulcherrima Willd. ex Klotzsch.

O objetivo deste trabalho foi identificar e quantificar, por Cromatografia Líquida de Alta Eficiência (CLAE), e massas exatas as antocianinas presente nas folhas de Euphorbia pulcherrima