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.

Selective Production of Levulinic Acid from Furfuryl Alcohol in THF Solvent Systems over H-ZSM-5

Abstract: Furfuryl alcohol in high concentrations (1 M) was hydrolyzed to levulinic acid in high yields (>70%) using H-ZSM-5 zeolite as the catalyst in monophasic tetrahydrofuran (THF)–water solvent systems. Reaction kinetics studies using H-ZSM-5 were carried out, and combined with results obtained for other Bronsted acid catalysts, we suggest that the structural properties of H-ZSM-5, in conjunction with increased reaction performance using the polar aprotic solvent THF, are effective for furfuryl alcohol hydrolysis to levulinic acid while inhibiting furfuryl alcohol polymerization reactions. In addition, on the basis of results obtained for a wide range of THF–H2O solvent systems (19:1–1:2 w/w), we suggest that the hydrophobic nature of H-ZSM-5 alters the internal solvent microenvironment within the zeolite framework, allowing for high levulinic acid yields, even at low THF solvent concentrations (e.g., 1:2 THF–H2O w/w).

Rabi model beyond the rotating-wave approximation: Generation of photons from vacuum through decoherence

Abstract: We study numerically the dynamics of the Rabi Hamiltonian, which describes the interaction of a single cavity mode and a two-level atom without the rotating wave approximation. We analyze this system subjected to damping and dephasing reservoirs, included via the usual Lindblad superoperators in the master equation. We show that the combination of the antirotating term and the atomic dephasing leads to linear asymptotic photon generation from the vacuum. We reveal the origins of the phenomenon and estimate its importance in realistic situations.

A novel ozone gas sensor based on one-dimensional (1D) α-Ag2WO4 nanostructures

Abstract: This paper reports on a new ozone gas sensor based on α-Ag2WO4 nanorod-like structures. Electrical resistance measurements proved the efficiency of α-Ag2WO4 nanorods, which rendered good sensitivity even for a low ozone concentration (80 ppb), a fast response and a short recovery time at 300 °C, demonstrating great potential for a variety of applications.

Development of restricted-access media supports and their application to the direct analysis of biological fluid samples via high-performance liquid chromatography

Abstract: A quick overview of published methods for analyzing compounds in complex biological samples reveals that the most difficult step is the clean-up or extraction of a required compound from the matrix. The strategy required to analyze exogenous compounds in biological fluids depends greatly upon the nature of the compound and upon the biomatrix. Coupled-column separation using restricted-access media as the first dimension in order to exclude macromolecules and retain micromolecules has been successfully used for a number of biological fluids. This paper presents the history of the development of restricted-access media supports and of their application to the direct injection of biological fluid samples in high-performance liquid chromatography.