Carlota González Gómez

Controlling carbon microporosity: the structure of carbons obtained from different phenolic resin precursors

Abstract Carbons were prepared from resins synthesised using the phenolic precursors phenol, para methylphenol, para ethylphenol, para n -propylphenol, para isopropylphenol and 3,5-dimethylphenol. Loss of phenolic OH from these materials was followed using solid-state nuclear magnetic resonance. The surface areas of the carbons were determined using N 2 and CO 2 adsorption. No significant differences in the loss of phenolic OH were observed. Under the same carbonisation conditions, the para alkyl phenols gave carbons with wide micropores, while the phenol and 3,5-dimethylphenol gave carbons with narrow micropores. Grinding the cured resins prior to carbonisation was found to significantly increase the surface area of the carbons obtained, with the microporous surface area increasing rapidly with a fall in particle size, without a significant increase in burn-off. Higher carbonisation temperatures widened the micropore size distribution, as shown by fitting the CO 2 adsorption isotherm with the Dubinin–Astakhov equation. The ability to change the carbon micropore structure obtained from a simple, well defined precursor, has many potential applications in carbon molecular sieves, catalyst supports and the investigation of adsorption processes.

Un análisis de las metas en situación de aprendizaje para el alumnado de primaria y secundaria obligatoria = Analysis of the goals for school children in primary and secondary school

RESUMEN Este trabajo se enmarca en dos contextos sobre la motivacion por el aprendizaje escolar: la teoria atribucional de Weiner (1986, 1995) y las aportaciones de Dweck (1986) sobre las metas que persigue el alumnado. El objetivo general es averiguar las metas que muestran los alumnos de primaria y secundaria obligatoria en situacion de aprendizaje, la relacion que mantienen estas metas con las diferentes dimensiones causales y si hay diferencias entre las metas de los estudiantes de secundaria obligatoria y las de los alumnos de primaria. La muestra la componen 722 alumnos de primaria y secundaria. Los resultados obtenidos indican que las metas coinciden con las halladas en otros contextos pero que se producen diferencias en funcion de la etapa educativa. ABSTRACT This work is based on two contexts regarding school learners motivation: the attribution theory by Weiner (1986, 1995) and the contributions made by Dweck (1986) about the goals schoolchildren expect to reach. The main aim of this work is to find the goals shown by primary and secondary school students during their learning stage, the relations these goals hold with the different causal dimensions and if there exist differences between the primary schoolchildren’s goals and those of the secondary school learners. The sample we have investigated consists of 722 students of both primary and secondary school. The results obtained indicate that their goals happen to be the same as those found in other contexts but that differences appear depending on the learning stage.