Navegando por Autor "Pires, Marcelo Amanajás"
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Item Comparing the nanoscale topography and interface properties of chitosan films containing free and nano-encapsulated copaiba essential oil : an atomic force microscopy (AFM) and fractal geometry study.(2023) Pinto, Erveton Pinheiro; Menezes, Rodrigo Prioli; Pires, Marcelo Amanajás; Zamora, Robert Ronald Maguiña; Araújo, Raquel Silva; Souza, Tiago Marcolino deThis article compared chitosan films containing copaiba essential oil (CO) and nano-encapsulated CO using nanoscaled topographic characteristics and interface properties. The CO-loaded nanocapsules (CO-NC) were prepared by the polymer nanoprecipitation method, whereas the composite films were produced by the casting method. The films’ surface was evaluated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Wettability and adhesion were also investigated by measuring the contact angle and AFM. The results suggested that the film’s surface containing CO-NC presented characteristics that favor interface interactions at the nanoscale. Furthermore, these films showed greater interaction with water and superior adhesion force than the control and CO-loaded chitosan films. Thus, considering the surface characteristics and the evaluated properties, CO-NC seems to be a promising alternative for incorporating CO in chitosan films.Item Lacunarity exponent and Moran index : a complementary methodology to analyze AFM images and its application to chitosan films.(2021) Pinto, Erveton Pinheiro; Pires, Marcelo Amanajás; Matos, Robert Saraiva; Zamora, Robert Ronald Maguiña; Menezes, Rodrigo Prioli; Araújo, Raquel Silva; Souza, Tiago Marcolino deIn this work, we developed new scripts to calculate the lacunarity exponent and Moran’s index of Atomic Force Microscopy (AFM) images. The lacunarity exponent was estimated by combining the Otsu binarization and gliding-box algorithm, and Moran index was introduced to evaluate the surfaces’ spatial autocorrelation. Developed scripts were first validated using numerical simulation of self-similar fractal and self-affine isotropic surfaces. Then, we successfully synthesized chitosan films with different glycerol con- centrations and used the lacunarity and Moran’s index for a thorough characterization. The validation of the proposed scripts using simulated Sierpinski Carpets and 3D artificial surfaces showed promising potential for analyzing AFM images. Finally, the methodology application to AFM images of chitosan films suggested that lacunarity analysis and Moran index determination could complement thin films’ quality processing control.