Federal University of São Carlos

About: Federal University of São Carlos is a education organization based out in São Carlos, Brazil. It is known for research contribution in the topics: Population & Microstructure. The organization has 16471 authors who have published 34057 publications receiving 456654 citations. The organization is also known as: UFSCar & Federal University of São Carlos.

Homogeneous nucleation versus glass transition temperature of silicate glasses

Abstract: This paper provides experimental and theoretical evidence for a correlation between the maximum internal nucleation rate, Imax=I(Tmax) [where Tmax is the temperature of maximum nucleation rate] and the reduced glass transition temperature, Tgr, for 51 glass-forming liquids. In addition, it demonstrates an analogous correlation between Tmax, the time-lag of nucleation at Tmax and the reduced glass transition temperature. An explanation is given for these remarkable trends.

Synthesis of TiO2-coated CoFe2O4 photocatalysts applied to the photodegradation of atrazine and rhodamine B in water

Abstract: Various strategies for the synthesis of anatase TiO2 nanoparticles and nanocomposites with particular morphologies and stability are currently generating a lot of interest and many research papers. In this study, composites of TiO2/CoFe2O4 in nanometric sizes were prepared by the polymeric precursor method. These materials were characterized by X-ray diffraction, Raman spectroscopy, surface area through N2 physisorption, Zeta potential, scanning and high-resolution transmission electron microscopy. The photocatalytic potential of the nanocomposites prepared was assessed by photodegradation of rhodamine B dye and atrazine pesticide under UV light. The materials showed photocatalytic activity due to the presence of TiO2 on their surface, associated with the magnetic activity of CoFe2O4 cores, which is useful for the separation and recovery of the photocatalysts after use in an oxidative process. In rhodamine photodegradation, pure TiO2 showed higher photocatalytic efficiency than the nanocomposites. However, in atrazine photodegradation, the nanocomposites were more effective, being this effect attributed to difference in charge at the surface of pure TiO2 and of nanocomposites, which enables adsorption processes of atrazine molecules on nanocomposites surface, and consequently, their higher photoactivity.

Unusual interactions binding iron tetrasulfonated phthalocyanine and poly(allylamine hydrochloride) in layer-by-layer films

Abstract: Molecular-level interactions are found to bind iron tetrasulfonated phthalocyanine (FeTsPc) and the polyelectrolyte poly(allylamine hydrochloride) (PAH) in electroactive layer-by-layer (LBL) films. These interactions have been identified by comparing Fourier transform infrared (FTIR) and Raman spectroscopy data from bulk samples of FeTsPc and PAH with those from FeTsPc/PAH LBL films. Of particular importance were the SO3- -NH3 interactions that we believe to bind PAH and FeTsPc and the interactions between unprotonated amine groups of PAH and the coordinating metal of the phthalocyanine. The multilayer formation was monitored via UV−vis spectroscopy by measuring the increase in the Q band of FeTsPc at 676 nm. Film thickness estimated with profilometry was ca. 11 A per bilayer for films adsorbed on glass. Reflection absorption infrared spectroscopy (RAIRS) revealed an anisotropy in the LBL film adsorbed on gold with FeTsPc molecules oriented perpendicularly to the substrate plane. Cyclic voltammograms show...