Abstract This study aims to investigate the effect of Viola tricolor extract on hippocampal neuronal death, interleukin (IL) -6 and IL-10 expression, spatial memory, anxiety, and depression in rats exposed to chronic immobilization stress. Rats were divided into groups Control, Viola300, Viola600, Stress, Stress-Viola300, and Stress-Viola600. Animals were placed in a restrainer (6 h / 21 days) to stress exposure. V. tricolor hydro-alcoholic extract was also administrated at doses of 300 and 600 mg/kg by gavage. The extract caused immobilized animals to spend more time in the target quadrant in the Morris water maze test. It also increased the percentage of entries into the open arm and the percentage of time spent in the open arm of the elevated plus-maze in immobilized rats. Treatment with the V. tricolor extract significantly reduced the immobility time of stressed rats in the forced swimming test. Furthermore, it significantly reduced neuronal death and expression of IL-6 in the hippocampus of immobilized animals but could not prevent the decrease of IL-10 expression. We concluded that V. tricolor protects rats from stress-induced behavioral damages, at least in part, by suppressing neuronal death and decreasing IL-6 expression.

Abstract In this paper, a size-dependent microscale plate model is developed to describe the bending, buckling and free vibration behaviors of microplates made of functionally graded materials (FGMs). The size effects are captured based on the modified strain gradient theory (MSGT), and the formulation of the paper is on the basis of Mindlin plate theory. The presented model accommodates the models based upon the classical theory (CT) and the modified couple stress theory (MCST) if all or two scale parameters are set to zero, respectively. By using Hamilton's principle, the governing equations and related boundary conditions are derived. The bending, buckling and free vibration problems are considered and are solved through the generalized differential quadrature (GDQ) method. A detailed parametric and comparative study is conducted to evaluate the effects of length scale parameter, material gradient index and aspect ratio predicted by the CT, MCST and MSGT on the deflection, critical buckling load and first natural frequency of the microplate. The numerical results indicate that the model developed herein is significantly size-dependent when the thickness of the microplate is on the order of the material scale parameters.

In this paper, the free vibration behavior of post-buckled functionally graded (FG) Mindlin rectangular microplates are described based on the modified couple stress theory (MCST). This theory enables the consideration of the size-effect through introducing material length scale parameters. The FG microplates made of a mixture of metal and ceramic are considered whose volume fraction of components is expressed by a power law function. By means of Hamilton's principle, the nonlinear governing equations and associated boundary conditions are derived for FG micro-plates in the postbuckling domain. The governing equations and boundary conditions are then discretized by using the generalized differential quadrature (GDQ) method before solving numerically by the pseudo-arclength continuation technique. In the solution procedure, the postbuckling problem of microplates is investigated first. Afterwards, the free vibration of microplates around the buckled configuration is discussed. The effects of dimensionless length scale parameter, material gradient index and aspect ratio on the on the postbuckling path and frequency of FG microplates subject to arbitrary edge supports are thoroughly discussed.

No presente trabalho é apresentado um método para a determinação de Cu em amostras de cabelo humano e água por voltametria de redissolução anódica de pulso diferencial. Foi provado que a eletropolimerização do pirrol ocorre em presença do ânion dopante Nitroso-R. O polipirrol dopado com Nitroso-R foi deposido sobre a superfície da platina, e reage com Cu(II) em pHs neutros, originando um complexo. Essa complexação entre o Nitroso-R e o Cu(II) produz o acúmulo de Cu(II) na superfície a partir de a circuito aberto. O eletrodo resultante com Cu(II) complexado foi então transferido para um tampão de acetato, e submetido a voltametria de redissolução anódica, promovendo o aparecimento de um pico de corrente a +0,08 V. Depois da avaliação do comportamento funcional analítico foi construído um gráfico de calibração a partir de 1,2 a 243,9 ng mL-1 e o limite de detecção foi de 0,7 ng mL-1. O método foi utilizado para a determinação de íons cobre em amostras de água e cabelo humano. Os resultados indicam a capacidade do método para a determinação deste íon em amostras reais. Além disso, a rápida e conveniente regeneração do eletrodo permite sua utilização em várias análises.

In the present paper a method for the determination of Cu in human hair and water samples by differential pulse anodic stripping voltammetry is presented. It has been proven that pyrrole electropolymerizes in present of Nitroso-R as dopant anion. Nitroso-R doped in polypyrrole film coated on platinum surface then reacts with Cu(II) in neutral pHs giving rise to a complex. This complexation between Nitroso-R and Cu(II) achieves the accumulation of Cu(II) from the sample solutions to the electrode surface at open circuit condition. The resulting electrode with complexed Cu(II) can then transfer to an acetate buffer and subject to anodic stripping voltammetry which promotes the appearance of a peak at +0.08 V. After the evaluation of the analytical performance a calibration graph was constructed from 1.2 to 243.9 ng mL-1 and the detection limit was 0.7 ng mL-1. The method was used for determination of copper ions in water and human hair samples. The results indicate the ability of method for the determination of this ion in real samples. Also, the rapid and convenient regeneration of electrode allows the use of a single modified electrode in multiple analyses.