Recife PE, Brazil
Recife PE, Brazil

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Freitas-Ribeiro G.M.,CCEN | Freitas-Ribeiro G.M.,Federal University of Paraiba | Fonseca C.C.,Federal University of Viçosa | Sartori S.S.R.,Federal University of Viçosa | And 3 more authors.
Anais da Academia Brasileira de Ciencias | Year: 2012

The nervous and endocrine systems jointly control intestinal movements, secretions of their glands and also participate of the processes of nutrient digestion and absorption. Therefore, the central objective of this study was to verify the existence of a possible relationship between the number of nervous cells and ganglia of the submucosal and myenteric plexuses and the number of endocrine cells in the small intestine of adult D. aurita. The utilized staining techniques were Grimelius, modified Masson-Fontana, direct immunoperoxidase and H-E. Argyrophillic, argentaffin and insulin immunoreactive endocrine cells do not numerically vary between the initial, mid and final regions of the duodenum, jejunum and ileum (P>0.05), except for argyrophillic cells in the jejunum (P>0.05). No numerical relationship has yet been verified between the number of nerve ganglia and endocrine cells, and also between nervous and endocrine cells. We recommended the use of new immunohistochemical techniques to confirm the numerical correlation between the nervous and endocrine systems in the small intestine. The morphology and distribution of endocrine cells and the nerve ganglia studied were similar to those encountered in eutherian mammals.

Botelho J.R.,CCEN | Pinheiro C.D.,Federal University of Campina Grande | Gondim A.D.,CCEN | Dunstan P.O.,University of Campinas | And 2 more authors.
Journal of Chemical and Engineering Data | Year: 2011

The standard molar enthalpies of formation of crystalline dialkyldithiocarbamate chelates of mercury(II) were determined by using reaction-solution calorimetry. Two different complexes were studied: Hg(S 2CNR2)2 with R = CH3 (Me) and i-C3H7 (Pri). The enthalpies of formation for the mercury complexes were determined in 1,2-dichloroethane at 298 K. The hemolytic and heterolytic mean enthalpies of dissociation of the Hg-S bonds were calculated by using the standard molar enthalpy of the gaseous chelates. © 2011 American Chemical Society.

Proenza Y.G.,CCEN | De Souza M.A.F.,CCEN | De Souza M.A.F.,Federal University of Paraiba | Ventura E.,Federal University of Paraiba | And 2 more authors.
Physical Chemistry Chemical Physics | Year: 2014

The energetics of the ECO2, SN2@C and SN2@N channels of X- + CH3ONO2 (X = F, OH, CH2CN) gas-phase reactions were computed using the CCSD(T)/CBS method. This benchmark extends a previous study with X = OH [M. A. F. de Souza et al., J. Am. Chem. Soc., 2012, 134, 19004] and was used to ascertain the accuracy and robustness of nineteen density-functionals for describing these potential energy profiles (PEP) as well as the kinetic product distributions obtained from RRKM calculations. Assessments were based on the mean unsigned error (MUE), the mean signed error (MSE), the #best #worst (BW) criterion and the statistical confidence interval (CI) for the MSE. In general, double-hybrid (DH) functionals perform better than the range-separated ones, and both are better than the global-hybrid functionals. Based on the MUE and CI criteria the B2GPPLYP, B2PLYP, M08-SO, BMK, ωB97X-D, CAM-B3LYP, M06, M08-HX, ωB97X and B97-K functionals show the best performance in the description of these PEPs. Within this set, the B2GPPLYP functional is the most accurate and robust. The RRKM results indicate that the DHs are the best for describing the selectivities of these reactions. Compared to CCSD(T), the B2PLYP method has a relative error of only ca. 1% for the selectivity and the accuracy to provide the correct conclusion concerning the nonstatistical behavior of these reactions. © The Owner Societies 2014.

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.

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.

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.

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.

Eliziario S.A.,São Paulo State University | De Andrade J.M.,CCEN | Lima S.J.G.,CT | Paskocimas C.A.,Federal University of Rio Grande do Norte | And 5 more authors.
Materials Chemistry and Physics | Year: 2011

Chromium and cobalt oxides are widely used in the manufacture of industrial pigments. In this work, the Co(Co2-xCrx)O4 powders with different chromium concentrations (x = 0, 0.25 and 1) were synthesized by the polymeric precursor method, heat treatment between 600 and 1000 °C. These powders were characterized by X-ray diffraction, infrared spectroscopy, colorimetry, UV-vis absorption and X-ray photoelectron spectroscopies. Even with the addition of chromium, the XRD patterns revealed that all powders crystallize in a single spinel cubic structure. The spinels with higher cobalt amount, Co(CoCr)O4 and Co(Co1.75Cr 0.25)O4, displayed a dark color, without the Co 3+ reduction observed in Co3O4 between 900 and 950 °C. The spinel with higher chromium amount, CoCr2O 4, was green. The colors were directly related to the occupation of tetrahedral and octahedral sites by the chromophores, as well as to the different oxidation states of chromium and cobalt. The different optical band gap values estimated from UV-vis spectra suggested the existence of intermediary energy levels within the band gap. X-ray photoelectron spectroscopy confirmed an increasing presence of Co(III) and a decreasing amount of Cr(VI) with cobalt enrichment. © 2011 Elsevier B.V.

Ramalho E.F.S.M.,CCEN | Santos I.M.G.,CCEN | Maia A.S.,CCEN | Souza A.L.,CCEN | Souza A.G.,CCEN
Journal of Thermal Analysis and Calorimetry | Year: 2011

Chemical composition of oils and fats used in the biodiesel synthesis can influence in processing and storage conditions, due to the presence of unsaturated fatty acids. An important point is the study of the biodiesel thermal stability to evaluate its quality using thermal analysis methods. In this study the thermal stabilities of the poultry fat and of their ethyl (BEF) and methyl (BMF) biodiesels were determined with the use of thermogravimetry (TG/DTG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC), in different atmospheres. The TG/DTG curves of the poultry fat in synthetic air presented three decomposition steps while only one step was observed in nitrogen (N2) atmosphere. The DSC results indicated four exothermic enthalpic transitions in synthetic air and an endothermic transitions in N2 atmosphere attributed to the combustion process and to the volatilization and/or decomposition of the fatty acids, respectively. For both biodiesels the TG/DTG curves in air indicated two mass loss steps. In the DSC curves four exothermic transitions were observed in synthetic air besides an endothermic one in N2 atmosphere. © 2011 Akadémiai Kiadó, Budapest, Hungary.

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.

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