The controlled release of Salicylic Acid (SA) influences the concentration and collateral effects of the drug. This release refers to the matrix in which the SA is incorporated. Among the matrices, Fe3O4 nanoparticles (NPs) stand out, for transporting drugs to specific sites. The functionalization of Fe3O4 by bovine serum albumin (BSA) can improve colloidal and chemical stability, in addition to increasing interactions with drugs. Thus, understanding the release kinetics of the AS incorporated in Fe3O4-BSA is essential to improve the controlled release. The study aimed the synthesis, characterization and release of the SA into the Fe3O4-BSA NPs. The results showed the functionalization of the Fe3O4-BSA NPs was effective and the average size was below 30 nm. The NPs showed colloidal stability above the pH of 7.5 which can be used as a drug carrier in blood plasma. Drug encapsulation into the NPs system was efficient (~91%) with about 30% of drug loading capability. The kinetic results showed the SA release mechanism was controlled by diffusion. The conclusion is that the incorporation of SA in Fe3O4-BSA NPs led to a release of SA in the first six hours, reaching equilibrium at 0.265 mg mL-1; and 1.83 mg.

La variedad de aplicaciones tecnológicas relacionadas a los dispositivos basados en óxidos semiconductores nanoestructurados ha despertado un gran interés en la comunidad científica, haciendo con que los estudios relacionados a estos materiales han aumentado en los últimos años. Entre estos materiales, se encuentra el óxido de zinc (ZnO), que presenta aplicaciones en las más diversas áreas, desde diodos emisores de luz (LEDs) a los dispositivos fotovoltaicos en células solares. Con el conocimiento de que las propiedades químicas y físicas que confieren a estos materiales las posibilidades de aplicación en dispositivos tecnológicos son fuertemente dependientes de las rutas de síntesis empleadas para la obtención de los mismos, presentamos en este trabajo una investigación con respecto de las modificaciones morfológicas ocurridas en partículas de ZnO, cuando el mismo es expuesto a un tratamiento sonoquímico, además de las influencias de los parámetros relacionados a éste método de síntesis en la obtención de este material. Para analizar los parámetros presentados anteriormente, tres muestras fueron preparadas, dos de ellas manteniendo la amplitud y variando el tiempo de sonicación y otra manteniendo el tiempo y variando la amplitud de sonicación, durante el tratamiento sonoquímico. El análisis de los resultados obtenidos indica que el tratamiento sonoquímico conduce a modificaciones morfológicas superficiales en las partículas de ZnO, además estas modificaciones se presentaron más evidentes cuando una mayor amplitud y un mayor tiempo de sonicación fueron utilizados en la síntesis de las muestras.

A variety of technological applications related to oxide semiconductor-based devices have attracted great interest among the scientific community, leading to an increase in studies of these materials during the last years. Among such materials, zinc oxide (ZnO) has applications in several areas, from light- emitting diodes (LEDs) to photovoltaic devices in solar cells. Considering the physical and chemical properties conferred to these materials, the possibilities of application in technological devices depend greatly on the synthesis routes employed. Accordingly, we investigated the morphological modifications in ZnO particles when subjected to sonochemical treatment and the influence of related synthesis method parameters, such as the time and amplitude of sonication. To analyze such effects, four samples were prepared with different sonochemical treatment conditions: in two, the amplitude of sonication was kept constant while varying the time of sonication, and in the other two, the time was kept constant while varying the amplitude. The analysis of the results obtained indicated that sonochemical treatment led to superficial morphological modifications in ZnO particles. Furthermore, these modifications became more apparent when higher amplitude and longer time of sonication were employed in sample synthesis.

The carbon dioxide reforming of methane was carried out over nickel catalysts supported on the gamma-Al2O3/CeO2 system prepared by wet impregnation. With the increase of the CeO2 weight in the catalyst, a higher stability was observed in the catalytic activity, together with an excellent resistance to carbon deposition and a better Ni dispersion. The catalysts were characterized by means of surface area measurements, TPR, H2 chemisorption, XRD, SEM, EDX, XPS and TEM. An interaction between Ni and CeO2 was observed to the Ni/CeO2 sample after activation in a H2 atmosphere above 300 ºC. Such behavior has a significantly influence on the catalytic activity.

Nickel nanoparticles supported on amorphous silica ceramic matrix were synthesized by the polymeric precursor method. The nanostructure was characterized by NMR, BET, XRD, SEM, TEM, and flame atomic absorption spectrometry techniques. It was observed a dependence of the crystallite size on the thermal annealing, under a N2 atmosphere. The materials presented a high catalytic activity and selectivity upon the beta-pinene hydrogenation reaction. The magnetic hystereses were also correlated with the morphology of the processed material.