Interdisciplinary graduate programs: application of the MACBETH multicriteria method for assessing their performances

Annals of Operations Research - This paper, employing the multicriteria method of decision support MACBETH, proposes a model for the evaluation of interdisciplinary graduate programs, based on...     

Development of a chromatographic low pressure flow injection system: Application to the analysis of methylxanthines in coffee

In this work, the coupling of a commercial monolithic column to a traditional low pressure FIA system is proposed for the analysis of theobromine, theophylline and caffeine in coffee brewed samples using UV detection.     

Electrochemical behavior of europium perovskites (Ca<Subscript>0.6</Subscript>Eu<Subscript>0.4</Subscript>MnO<Subscript>3</Subscript>) in alkaline aqueous media

In this paper, the electrochemical behavior of europium perovskites (Ca_0.6Eu_0.4MnO₃) prepared by a gel combustion method followed by a thermal treatment performed at 1073 and 1473 K is compared with the pristine oxide CaMnO₃ (T = 1073 K) obtained by the same method. The experiments were performed in alkaline aqueous media via open-circuit potential, cyclic voltammetry, chronopotentiometry, and impedance spectroscopy. The data show that the electrode roughness is inversely proportional to the oxide particle size. The chronopotentiometric curves show also that the presence of europium is advantageous due to the increase of the electrode roughness for the oxides formed at the same temperature (1073 K) or by increasing the charge per unit area for the oxide formed at 1473 K. The impedance spectra, which were obtained in the capacitive behavior domain, reflect the porous morphology of the electrode surfaces according to the theory developed by Levie. This feature is particularly evident for the electrodes with an average particle diameter of 90 and 60 nm, corresponding respectively to the oxides CaMnO₃ and Ca_0.6Eu_0.4MnO₃, both formed at 1073 K.     

An Alternative Approach to the Electric Charge Quantization with Non-global Potentials

We present an alternative approach to justify the electric charge quantization by means of non-global electromagnetic potentials. We adopt a non-global potential whose singularity does not goes over to infinity and can be entirely embedded into an arbitrarily small closed ball.     

Functionalization of Rhodamine Platforms with 3-Hydroxy-4-pyridinone Chelating Units and Its Fluorescence Behavior towards Fe(III)

Functionalization of xanthene fluorophores with specific receptor units is an important topic of research aiming for the development of new analytical tools for biological sciences, clinical diagnosis, food and environmental monitoring. Herein, we report a new dihydrorosamine containing two active amino groups, which was functionalized with 3-benzyloxy-1-(3′-carboxypropyl)-2-methyl-4-pyridinone through an amide coupling strategy. Benzylated mono- and di-functionalized dihydrorosamine derivatives (H in position 9 of the xanthene) were obtained, but with modest reaction yields, requiring long and laborious purification procedures. Looking for a more efficient approach, rhodamine 110 was selected to react with the carboxypropyl pyridinone, enabling the isolation of the corresponding mono- and di-functionalized derivatives in amounts that depend on the excess of pyridinone added to the reaction. The structure of all compounds was established by ¹H and ¹³C NMR, MS (ESI) and their absorption and emission properties were evaluated in dichloromethane. The fluorescence behavior of the debenzylated mono-rhodamine 110 derivative in the presence of Fe(III) was studied, making it an interesting fluorogenic dye for future optical sensing applications.     

Catalytic activity of aluminium and copper-doped magnetite in the high temperature shift reaction

Aluminium and copper-doped magnetite was evaluated as high temperature shift catalyst and compared with a hematite-based sample. The first one is less active but can save energy in industrial processes. This revised version was published online in June 2006 with corrections to the Cover Date.     

A flow system with in-line blank correction applied to the spectrophotometric determination of total iron and chromium (VI) in wastewaters

A flow system using the sample as the carrier with a propulsion device located after the detector is presented. This approach allows the correction of the intrinsic color of the sample, as it provides baseline adjustment for each sample. A confluence situated just after the selection valve allows the sample composition to be adjusted for the colorimetric measurement. The developed methodology was applied to the colorimetric determination of total Fe and Cr (VI) in wastewaters at 0.1-6.0 mg L-1 and 0.03-1.0 mg L-1, respectively. RSDs lower than 3% and a sampling rate of approximately 40 h-1 were obtained.