This study presents an alternative, rapid, and environment-friendly synthesis procedure of a magnetic core-shell mesoporous SBA-15 silica composite, its functionalization with 4-amino-3-hydrazino-5mercapto-1,2,4-triazole (Purpald), and its application in dispersive solid-phase microextraction (DSPME) for Cu(II) from water. The materials were characterized through magnetization measurements, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) of 29 Si and 13 C, elemental analysis, and surface area measurements. FTIR and NMR analyses indicated the presence of the ligand on the functionalized material and that it was coupled through a C S bond. TEM images clearly show that the magnetite core particles were effectively coated with a silica shell. The material presented a surface area of 287.99 m 2 g −1 and an average pore diameter of approximately 15.1 nm. The material had its point of zero charge (PZC) determined (6.17) and its adsorption capacity was evaluated as a function of time, pH, and metal concentration. Dynamic adsorption equilibrium was reached in 120 min, and it had a good correlation with the pseudo-second-order kinetic model (r 2 = 0.9997). The maximum experimental adsorption capacity (0.0786 mmol g −1) and the value calculated by the linearized Langmuir model (0.0799 mmol g −1) are very approximate, indicating the formation of a monolayer over the material. Furthermore, the material proved to be very stable, because their adsorption capacity remained greater than 95% even after 10 cycles of adsorption/desorption. A high enrichment factor of 98.1-fold was observed, indicating that this material is suitable for the preconcentration of trace Cu(II) ions before analysis through flame atomic absorption spectrometry (FAAS).

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High temperature solid oxide fuel cells (SOFCs) offer an environmentally friendly technology to convert gaseous fuels such as hydrogen, natural gas or gasified coal into electricity at high efficiencies. Besides the efficiency, higher than those obtained from the traditional energy conversion systems, a fuel cell provides many other advantages like reliability, modularity, fuel flexibility and very low levels of NO x and SO x emissions. The high operating temperature (950-1000 °C) used by the current generation of the solid oxide fuel cells imposes severe constraints on materials selection in order to improve the lifetime of the cell. Besides the good electrical, electrochemical, mechanical and thermal properties, the individual cell components must be stable under the fuel cell operating atmospheres. Each material has to perform not only in its own right but also in conjunction with other system components. For this reason, each cell component must fulfill several different criteria. This paper reviews the materials and the methods used to fabricate the different cell components, such as the cathode, the electrolyte, the anode and the interconnect. Some remarkable results, obtained at IPEN (Nuclear Energy Research Institute) in São Paulo, have been presented.

Iron-excess Mn-Zn ferrite nanoparticles were prepared by coprecipitation with sodium hydroxide (NaOH) at different concentrations (0.1, 0.2, 0.5 and 1.0 mol/L). The results of X-ray diffraction (XRD) analysis using Whole Powder Pattern Modeling (WPPM) showed that higher concentrations of NaOH promote crystallite growth and broader dispersion in crystallite sizes. Energy dispersive X-ray spectroscopy indicates that zinc loss is noticeable when [NaOH] ≥ 0.2 mol/L. XRD revealed also a significant less-crystalline phase contribution alongside the main peaks of the nanocrystalline cubic spinel ferrite phase. The less-crystalline fraction is lower for the ferrite obtained with 0.2 mol/L of NaOH, being about 50% and more than 70% for the other samples. Despite of the less-crystalline fraction and the excess of iron, no secondary phases were detected. The Warren curves showed that the concentration of NaOH significantly influences the microstrain in the crystallites, being smaller for the sample obtained with NaOH at 0.2 mol/L. The sample prepared with this condition presented the better properties to be used as magnetic tracer in clinical diagnoses combining small mean crystallite size, low microstrain, which resulted in materials with higher magnetic saturation and high surface charge under blood pH.

This study aimed to evaluate the effect of various zirconia surface pretreatments on the adhesion between full contour 3Y-TZP zirconia and glaze, and the shear bond strength (SBS) between glazed/3Y-TZP and resin cement. Specimens were allocated into groups: GL-glaze; AL+GL-sandblasting with Al 2 O 3 +GL; CJ+GL-tribochemical silica coating (Cojet ® /CJ)+GL; PS+GL-piranha solution+GL; and CJ. Adhesion between 3Y-TZP and GL was evaluated using the scratch test. Surface topography and glaze thickness were evaluated by using a scanning electron microscope (SEM). For SBS, glazed/3Y-TZP surface was etched with hydrofluoric acid and a silane was applied. For CJ only the silane was applied. Samples were tested after 24 h (24 h wet) or after 15,000 thermal cycles and 90 days storage (thermocycled). After SBS, the type of failure was classified as: adhesive, mixed or cohesive. The data were analyzed using two-way ANOVA and Tukey's test. SEM analysis after scratch test revealed circular cracks in the GL group and conformal cracks in the others groups. SEM micrographs suggested that zirconia specimens submitted to airborne-particle abrasion presents rougher and porous surface when compared to surfaces treated with GL and PS. The glaze layer was approximately 1.86 µm thick in all groups. After 24 h, SBS test showed highest values for AL+GL and CJ+GL and were significantly higher when compared to the GL group. Differences were not significant between PS+GL and the other groups. After aging (thermo-cycling+storage), groups GL and CJ presented no statistically significant difference compared to 24 h and aged AL+GL, CJ+GL and PS+GL groups. The predominant type of failure was mixed. 3Y-TZP surface treatment with glaze application could be considered as an alternative treatment, since it yielded a similar resin bond strength without the need for airborne-particle abrasion.