2 resultados para secure European System for Applications in a Multi-Vendor Environment (SESAME)
em Academic Archive On-line (Stockholm University
Resumo:
The major part of this thesis concerns the development of catalytic methodologies based on palladium nanoparticles immobilized on aminopropyl-functionalized siliceous mesocellular foam (Pd0-AmP-MCF). The catalytic activity of the precursor to the nanocatalyst, PdII-AmP-MCF is also covered by this work. In the first part the application of Pd0-AmP-MCF in Suzuki-Miyaura cross-coupling reactions and transfer hydrogenation of alkenes under microwave irradiation is described. Excellent reactivity was observed and a broad range of substrates were tolerated for both transformations. The Pd0-AmP-MCF exhibited high recyclability as well as low metal leaching in both cases. The aim of the second part was to evaluate the catalytic efficiency of the closely related PdII-AmP-MCF for cycloisomerization of various acetylenic acids. The catalyst was able to promote formation of lactones under mild conditions using catalyst loadings of 0.3 - 0.5 mol% at temperatures of up to 50 oC in the presence of Et3N. By adding 1,4-benzoquinone to the reaction, the catalyst could be recycled four times without any observable decrease in the activity. The selective arylation of indoles at the C-2 position using Pd-AmP-MCF and symmetric diaryliodonium salts is presented in the third part. These studies revealed that Pd0-AmP-MCF was more effective than PdII-AmP-MCF for this transformation. Variously substituted indoles as well as diaryliodonium salts were tolerated, giving arylated indoles in high yields within 15 h at 20 - 50 oC in H2O. Only very small amounts of Pd leaching were observed and in this case the catalyst exhibited moderate recyclability. The final part of the thesis describes the selective hydrogenation of the C=C in different α,β-unsaturated systems. The double bond was efficiently hydrogenated in high yields both under batch and continuous-flow conditions. High recyclability and low metal leaching were observed in both cases.
Resumo:
The aim of this research is to provide insight into how middle school learners experience an inclusive multicultural learning environment. Increasing diversity is challenging European educational systems, which have the arduous task to foster inclusion of learners with diverse educational needs. In order to explore the participants’ descriptions, a qualitative approach based on semi-structured interviews with six learners was employed. Learners’ positions in the educational scenery are central and unique; they are the main experts on their own situations and therefore precious contributors to educational research. Results have been discussed according to a sociocultural perspective. The analysis of my data suggests that the learners perceive their inclusive environment as beneficial. Moreover, they perceive their cultural diversity as strength, reckon social interaction and teamwork with peers as favorable conditions for learning, feel competent in multicultural communication and believe that respect and acceptance towards others are necessary common values. Some implications of multiculturalism in special education are discussed according to the results of a recent European study, which shows that in all the participating European countries, Sweden included, there is a consistent discrepancy in the proportions of learners with immigrant background within special education. Assessment methods developed for mono-cultural learners appear to be a valid reason why multicultural learners are over-or under-represented in special education. Research also shows that inclusion of diversity in educational environment enables the development of social skills in all learners.