Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto

About: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto is a based out in . It is known for research contribution in the topics: Population & Catalysis. The organization has 2143 authors who have published 3674 publications receiving 71071 citations. The organization is also known as: FFCLRP & FFCLRP-USP.

Narrow Optical Homogeneous Linewidths in Rare Earth Doped Nanocrystals

Abstract: A homogeneous linewidth of $85.6\ifmmode\pm\else\textpm\fi{}4.4\text{ }\text{ }\mathrm{kHz}$ is reported in 60 nm ${\mathrm{Eu}}^{3+}$ doped ${\mathrm{Y}}_{2}{\mathrm{O}}_{3}$ nanocrystals at 1.3 K. This linewidth was measured by two-pulse photon echoes on highly scattering powders using heterodyne detection. Spectral diffusion was also investigated by three-pulse photon echoes and resulted in a limited broadening of the homogenous linewidth of about 250 kHz over $120\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$. Compared to achievable Rabi frequencies, in the range of several MHz, these values show that rare earth doped nanocrystals can be useful for applications in optical quantum information processing.

Seasonal variation in food resource and forest strata use by brown capuchin monkeys (Cebus apella) in a disturbed forest fragment.

Abstract: Different animal species are affected differently by human habitat degradation; some vanish with the first alterations while others are even able to benefit from human activity. Capuchin monkeys (genus Cebus) show great behavioural flexibility and learning capacities, in the field as well as in captivity [1–4]. The genus is hence able to adapt to and cope with both varying environmental conditions and, to a certain degree, with human impact [5–8]. The aim in this short-term study on Cebus apella in a disturbed forest fragment was to investigate flexibility in foraging strategies and associated changes in forest strata use between the dry season, with a food shortage, and the rainy season.

Effect of Erythrina velutina and Erythrina mulungu in rats submitted to animal models of anxiety and depression

Abstract: Erythrina velutina (EV) and Erythrina mulungu (EM), popularly used in Brazil as tranquilizing agents, were studied. The effects of acute and chronic oral treatment with a water:alcohol extract of EV (7:3, plant grounded stem bark; acute = 100, 200, 400 mg/kg; chronic = 50, 100, 200 mg/kg) were evaluated in rats (N = 11-12) submitted to the elevated T-maze (for avoidance and escape measurements) model of anxiety. This model was selected for its presumed capacity to elicit specific subtypes of anxiety disorders recognized in clinical practice: avoidance has been related to generalized anxiety and escape to panic. Additionally, animals were treated with the same doses of EV and EM (water:alcohol 7:3, inflorescence extract) and submitted to the forced swim test for the evaluation of antidepressant activity (N = 7-10). Both treatment regimens with EV impaired elevated T-maze avoidance latencies, without altering escape, in a way similar to the reference drug diazepam (avoidance 1, mean ± SEM, acute study: 131.1 ± 45.5 (control), 9.0 ± 3.3 (diazepam), 12.7 ± 2.9 (200 mg/kg), 28.8 ± 15.3 (400 mg/kg); chronic study: 131.7 ± 46.9 (control), 35.8 ± 29.7 (diazepam), 24.4 ± 10.4 (50 mg/kg), 29.7 ± 11.5 (200 mg/kg)). Neither EV nor EM altered measurements performed in the forced swim test, in contrast to the reference drug imipramine that significantly decreased immobility time after chronic treatment. These results were not due to motor alterations since no significant effects were detected in an open field. These observations suggest that EV exerts anxiolytic-like effects on a specific subset of defensive behaviors which have been associated with generalized anxiety disorder.

Purification and biochemical characterization of a thermostable extracellular glucoamylase produced by the thermotolerant fungus Paecilomyces variotii

Abstract: An extracellular glucoamylase produced by Paecilomyces variotii was purified using DEAE-cellulose ion exchange chromatography and Sephadex G-100 gel filtration. The purified protein migrated as a single band in 7% PAGE and 8% SDS-PAGE. The estimated molecular mass was 86.5 kDa (SDS-PAGE). Optima of temperature and pH were 55 °C and 5.0, respectively. In the absence of substrate the purified glucoamylase was stable for 1 h at 50 and 55 °C, with a t50 of 45 min at 60 °C. The substrate contributed to protect the enzyme against thermal denaturation. The enzyme was mainly activated by manganese metal ions. The glucoamylase produced by P. variotii preferentially hydrolyzed amylopectin, glycogen and starch, and to a lesser extent malto-oligossacarides and amylose. Sucrose, p-nitrophenyl α-d-maltoside, methyl-α-d-glucopyranoside, pullulan, α- and β-cyclodextrin, and trehalose were not hydrolyzed. After 24 h, the products of starch hydrolysis, analyzed by thin layer chromatography, showed only glucose. The circular dichroism spectrum showed a protein rich in α-helix. The sequence of amino acids of the purified enzyme VVTDSFR appears similar to glucoamylases purified from Talaromyces emersonii and with the precursor of the glucoamylase from Aspergillus oryzae. These results suggested the character of the enzyme studied as a glucoamylase (1,4-α-d-glucan glucohydrolase).