Electrooxidation and determination of dopamine using a Nafion®-cobalt hexacyanoferrate film modified electrode

The electrocatalysis of dopamine has been studied using a cobalt hexacyanoferrate film (CoHCFe)-modified glassy carbon electrode. Using a rotating disk CoHCFe-modified electrode, the reaction rate constant for dopamine was found to be 3.5 × 105 cm3 mol-1 s-1 at a concentration of 5.0 × 10-5 mol L-1. When a Nafion® film is applied to the CoHCFe-modified electrode surface a high selectivity for the determination of dopamine over ascorbic acid was obtained. The analytical curve for dopamine presented linear dependence over the concentration range from 1.2 × 10-5 to 5.0 × 10-4 mol L-1 with a slope of 23.5 mA mol-1 L and a linear correlation coefficient of 0.999. The detection limit of this method was 8.9 × 10-6 mol L-1 and the relative standard deviation for five measurements of 2.5 × 10-4 mol L-1 dopamine was 0.58%

El rendimiento académico de dos poblaciones de alumnos, una con asistencia presencial a clase, otra bajo la modalidad virtual

Este es un tiempo de cambios, el ámbito de la enseñanza aprendizaje, no puede quedar ajeno a los mismos. Para adaptarse a las necesidades de la sociedad actual, las Universidades deben flexibilizarse y desarrollar vías de integración de las tecnologías de la información y la comunicación (TIC) en los procesos de formación. Las TIC experimentan un desarrollo constante y rápido. Ya en 1958, aparece el primer programa para la enseñanza dedicado a la aritmética binaria, desarrollado por Raht y Anderson, con un ordenador IBM 650, han pasado más de 50 años desde este acontecimiento y en nuestras universidades todavía hay docentes que no saben utilizar las TIC. El rendimiento académico es una preocupación continua de los docentes, el aprendizaje ha traspasado los muros del salón de clases convencional, los alumnos y profesores se pueden comunicar obviando las barreras geográficas. Para adaptarnos debemos incorporar cambios en el rol del profesor, en el del alumno, cambios metodológicos y en estas transformaciones quedan implicadas directamente las instituciones

Social media in democratic transitions and consolidations: what can we learn from the case of Tunisia?

© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. The aim of this paper is to analyse the use of social media in the stages of uprising, democratic transition and democratic consolidation using the case study of Tunisia. While the impact of social media in uprisings has been widely documented in past research about the MENA region, Tunisia provides new evidence to the use of Internet in the processes of democratisation. Consequently, this research focuses in detail on the benefits but also the pitfalls of social media in transitions and consolidations. Data collection was based on interviews with Tunisian social media activists. The analysis is valuable to social media practitioners and researchers alike

Electrochemical behavior of the N-nosyl-protected amino acids in N,N-dimethylformamide

The electrochemical reduction of serine, glycine, and leucine protected by the 4-nitrobenzenesulfonyl, group in N,N-dimethylformamide at mercury cathode occurs at two steps. The first one at -0.8 V vs. SCE, after a one-electron transfer, leads the anion radical formation that dimerizes and adsorbs at electrode. In the second step at -1.4 V, an instable dianion forms which then cleaves. The mechanism is discussed

ELECTROCHEMICAL AND SPECTRAL RECOGNITION OF CHLORIDE-IONS BY NOVEL ACYCLIC RUTHENIUM(II) BIPYRIDYL RECEPTOR COMPLEXES

The electrochemical and spectral recognition of chloride anions by novel acyclic ruthenium(II) bipyridyl receptor complexes is demonstrated. The low energy metal-to-ligand charge-transfer (MLCT) emission band of the complexes and inherent sensitivity of the technique suggests that fluorescence emission spectroscopy offers particular promise in analytical applications. The principle of anion recognition based on the suitable design of the receptor complexes will be applicable to a range of analytes