Influencia del tratamiento térmico en la cristalización y rugosidad de películas delgadas de LiNbO3 depositadas por el método Spin Coating

Lithium niobate (LiNbO3) thin films with 1/1 stoichiometry were prepared by a spin-coating from polymeric precursor method. The films deposited on silicon (100) substrates, were thermally treated from 400° to 600°C for 3 hours in order to study the influence of thermal treatment on the crystallinity, microstructure, grain size and roughness. X-ray diffraction (XRD) results showed that LiNbO3 phase crystallizes at low temperature (400°C). It was observed by scanning electron microscopy (SEM) that it is possible to obtain dense thin films at temperatures around 500°C. The atomic force microscopy (AFM) results showed that the grain size and roughness are strongly influenced by the annealing temperature.

Effect of different bleaching protocols on dental enamel and composite resin

To evaluate changes in microhardness, roughness and surface morphology of dental enamel and composite resin after different tooth bleaching techniques. Material and Methods: Dental fragments from bovine incisors with composite resin restorations were submitted to different bleaching protocols: G1 – daily 8 hours application of a 10% carbamide peroxide (CP) gel during 21 days; G2: 3 applications of 15 minutes of a 38% hydrogen peroxide (H2O2) gel; G3: 38% H2O2 gel associated to irradiation with LED (470nm) during 6 minutes. The Knoop micro hardness of enamel and composite resin were evaluated at 1, 7, 14 and 21 days for G1, and after 1, 2 and 3 sessions for G2 and G3. The roughness and superficial morphology (atomic force microscopy) were evaluated before and at the end of the bleaching treatment. The data were analyzed by Mann-Whitney and Wilcoxon tests (=5%). Results: Significant reduction on enamel hardness was observed after 2 and 3 sessions for G2 and G3. For composite, the reduction occurred after 21 days for G1, and after 3 sessions for G2 and G3 (p<0.05). Significant reduction on roughness and superficial morphology were observed only for enamel of G1 group (p<0.05). Conclusion: The 10% CP gel promoted only superficial alterations on dental enamel, while the 38% H2O2 gel promoted mineral reduction of this dental tissue. All the bleaching protocols promoted reduction on hardness of composite resin.

Estudio descriptivo in vitro de dos agentes blanqueadores de distinta concentración sobre la micromorfología del esmalte bovino

Dental tooth bleaching is a conservative option for the treatment of tooth stains. It is based on the use of hydrogen peroxide as an active agent. Despite its effectiveness to lighten tooth colour, there is concern regarding its use due to the effects it could have over enamel surface. There is scarce evidence on the subject and contradictions exist between different authors. The aim of this study was to compare enamel surface micromorphology after bleaching teeth with different concentrations of hydrogen peroxide solutions. Method: 50 healthy bovine incisors sectioned horizontally at the cemento-enamel junction were prepared. Contents of pulp chamber and tooth surfaces were cleaned. The buccal surface of each tooth was divided vertically, assigning one half to the control group (CG) and the other randomly to: Group 1: 25 samples treated with 15% hydrogen peroxide with nitrogen doped titanium dioxide. Group 2: 25 samples treated with 35% hydrogen peroxide. Square samples (2x2 mm.) were obtained and observed by SEM (magnification of 5.000x and 10.000x). Results: All treated groups showed longitudinal depressions on the surface and increased surface roughness. Conclusions: Tooth bleaching with hydrogen peroxide produces subclinical alterations over bovine enamel surface. 15% hydrogen peroxide bleaching agent produced less micromorphology alteration over bovine enamel surface than the 35% hydrogen peroxide agent.

Wettability behavior of nanotubular TiO2 intended for biomedical applications

Nanotubes have been subject of studies with regard to their ability to promote differentiation of several cells lines. Nanotubes have been used to increase the roughness of the implant surfaces and to improve bone tissue integration on dental implant. In this study TiO2 nanotube layer prepared by anodic oxidation was evaluated. Nanotube formation was carried out using Glycerol-H2O DI(50-50 v/v)+NH4F(0,5 a 1,5% and 10-30V) for 1-3 hours at 37ºC. After nanostructure formation the topography of surface was observed using field-emission-scanning-microscope (FE-SEM). Contact angle was evaluated on the anodized and non-anodized surfaces using a water contact angle goniometer in sessile drop mode with 5 μL drops. In the case of nanotube formation and no treatment surface were presented 39,1° and 75,9°, respectively. The contact angle describing the wettability of the surface is enhanced, more hydrophilic, on the nanotube surfaces, which can be advantageous for enhancing protein adsorption and cell adhesion.

Geoprocessamento de variáveis morfométricas para caracterização da microbacia do Córrego do Petiço

This study aims to perform the morphometric characterization of the watershed stream Petiço, Botucatu-SP, through techniques of GIS by GIS IDRISI Selva and Charter planialtimetric Botucatu (SF-22-ZB-VI-3) , edited by IBGE (1969), scale 1: 50000 for ranking the drainage network and the morphometric analysis. The variables analyzed were the dimensions, the relief pattern, pattern of the drainage network and the shape variables. The results show that related to how the watershed has an oblong shape with environmental interpretation with low tendency to flooding and erosion. The sinuosity index of 1.22 shows that the channels of the micro tend to be somewhat sinuous, which allows to infer that is permeable soil with good water infiltration. Based on the results of the morphometric variables was found that the watershed is in good condition of conservation, however, presents certain risks of susceptibility to erosion, and environmental degradation in some points, being fundamental to the maintenance of vegetation cover, in view of the roughness coefficient (Rn). Thus, the evaluation of morphometric characteristics in the study watershed constitutes an important tool in conjunction with the use of GIS and Geographic Information Systems makes possible the planning and management of natural resources aimed at their conservation.