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Recife, Brazil

Agra-Neto A.C.,Federal University of Pernambuco | Napoleao T.H.,Federal University of Pernambuco | Pontual E.V.,Federal University of Pernambuco | De Lima Santos N.D.,Federal University of Pernambuco | And 4 more authors.
Parasitology Research | Year: 2014

The indiscriminate use of synthetic insecticides to control Aedes aegypti has led to emergence of resistant populations. Moringa oleifera seeds contain the lectins WSMoL and cMoL. WSMoL has larvicidal activity on fourth-stage of A. aegypti organophosphate-susceptible larvae (Rockefeller L4). This study reports on the effects of cMoL on the survival of Rockefeller L 4 as well as of WSMoL and cMoL on L4 from an organophosphate-resistant population (Rec-R). The effects of lectins on digestive (amylase, trypsin, and protease) and detoxifying (superoxide dismutase (SOD), α- and β-esterases) enzymes from larvae were also determined. cMoL (0.1-0.8 mg/ml) did not kill Rockefeller L4 as well as WSMoL and cMoL (0.1-0.8 mg/ml) were not larvicidal for Rec-R L4. WSMoL stimulated protease, trypsin-like, and α-amylase from Rockefeller L 4 while cMoL inhibited these enzymes. WSMoL had no effect on trypsin-like activity from Rec-R L4 but inhibited protease and α-amylase. Among digestive enzymes of Rec-R L4, cMoL inhibited only trypsin-like activity. cMoL inhibited SOD activities from Rockefeller and Rec-R L4 in a higher level than WSMoL while β-esterase from Rockefeller L4 was more inhibited by WSMoL. The lectins promoted low stimulation or inhibition of α-esterase activities from both populations. In conclusion, Rockefeller and Rec-R larvae were distinctly affected by M. oleifera lectins, and larvicidal mechanism of WSMoL on Rockefeller L4 may involve deregulation of digestive enzymes. cMoL interfered mainly on SOD activity and thus it can be investigated as a synergistic agent for controlling populations whose resistance is linked to an increased detoxifying process mediated by this enzyme. © 2013 Springer-Verlag Berlin Heidelberg. Source

Carvalho J.,Federal University of Campina Grande | Furtado C.,CCEN | Moraes F.,CCEN
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

In this work we study the interaction problem of a Dirac oscillator with gravitational fields produced by topological defects. The energy levels of the relativistic oscillator in the cosmic string and in the cosmic dislocation space-times are sensible to curvature and torsion associated to these defects and are important evidence of the influence of the topology on this system. In the presence of a localized magnetic field the energy levels acquire a term associated with the Aharonov-Bohm effect. We obtain the eigenfunctions and eigenvalues and see that in the nonrelativistic limit some results known in standard quantum mechanics are reached. © 2011 American Physical Society. Source

De Souza J.F.O.,CCEN | De Lima Ribeiro C.A.,State University of Feira de Santana | Furtado C.,CCEN
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

In this contribution, we study the effects caused by an impurity on the quantum dynamics of massive excitations in a disclinated graphene in the presence of an external magnetic field. Within a continuum approach, the problem is mathematically modeled by the definition of a special vector potential containing all the information about the topology and the interacting fields. The presence of disclination is introduced by a term in the Dirac equation that translates the appearance of a phase associated with the transport of the spinor around the apex of the cone. We solve exactly the Dirac equation for this problem and the eigenvalues are obtained. We observe the influence of the disclination on the spectrum of energy and the allowed values of magnetic field. © 2014 Elsevier B.V. Source

α- and β-Cyclodextrins cavity inclusion constants (K i) were determined for a series of benzaldehydes and acetophenones by using two different methods: Benesi-Hildebrand (BH) UV/vis spectroscopic method and electrochemical current (EC) method, determined by cyclic voltammetry. The values determined in the group of benzaldehydes varied from 322 ± 27 to 5688 ± 317 mol-1 dm3 for UV/vis method, and 342 ± 19 to 7386 ± 142 mol-1 dm3 for EC method. The values determined in the group of acetophenones varied from 2201 ± 88 to 9125 ± 251 mol-1 dm3 for UV/vis method, and 1473 ± 33 to 7555 ± 187 mol-1 dm3 for EC method. The equilibrium time estimated for UV/vis spectroscopic (BH) method was 240 min and for the cyclic voltammetry (EC) method was 310 min. Notably, despite their limitations, both methods were suitable and reliable for inclusion constant measurement, if the equilibrium time of the system is well established. © 2010 Elsevier Ltd. Source

Bueno M.J.,CCEN | Furtado C.,CCEN | De M. Carvalho A.M.,Federal University of Alagoas
European Physical Journal B | Year: 2012

In this work, we study the low-energy electronic spectrum of a graphene layer structure with a disclination in the presence of a magnetic field. We make this study using the continuum approach, where we use the geometric theory of topological defects to introduce a disclination in a graphene layer, and the electrons are described by the massless Dirac equation in this curved background. The bound states energy spectrum and eigenfunctions are also obtained and an explicit dependence was found on the parameter that characterizes the topological defect and on the magnetic field. © 2012 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg. Source

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