Promoció de sistemes micro-eòlics i desenvolupament de capacitats en energia renovable en països en desenvolupament

Informe final del projecte realitzat per al Centre de Cooperació per al Desenvolupament de la UPC.

Micro-insurance through corporate-NGO partnerships in West Bengal : opportunities and constraints

This Practical Note examines the nascent micro-insurance sector in West Bengal, paying particular attention to the corporate- NGO partnership model for micro-insurance distribution,which has been enabled by India's unique regulatory framework. We challenge the popularconstruction of this model as a 'win - win' for all parties by analysing conflicting understandings of micro-insurance schemes and their purposes by insurance companies, NGOs, and poorvillagers. The article also considers the role of the specific political context of West Bengal inconstricting corporate- NGO micro-insurance

Proposta metodológica para ensino de micro-biologia do solo

A conseqüência mais interessante de inserir pesquisa no ambiente de atividade educacional é a assimilação do conceito de conhecimento como uma construção teórica compartilhada pela comunidade científica. A idéia de conhecimento temporário e subjetivo deve ser desenvolvida na sala de aula. Mas, como um problema pode ser criado durante o desenvolvimento do conteúdo? Em Microbiologia Agrícola da Faculdade de Ciências Agropecuárias (Universidad Nacional de Entre Ríos), foi desenvolvido um trabalho de grupo durante cinco anos. Este trabalho foi caracterizado pelo princípio metodológico da resolução de problemas para auxiliar o processo de aprendizagem. Na sala de aula, os professores coordenaram as atividades e os estudantes desenvolveram e projetaram a experiência, baseando-se nos problemas levantados para obter resultados. Depois de analisados e discutidos, verificou-se que novos problemas e questões surgiram. Este método foi avaliado por meio de entrevista com os alunos leva a crer que sua utilização em sala de aula, tenha tornado a aprendizagem mais significativa.

Determinación de la dureza de los minerales mediante la medida de micro-huellas

En el presente trabajo se describe el método de la determinación de la dureza efectuando las mediciones a escala microscópica. Se establece la relación entre la escala de dureza de Mohs y las unidades Vickers de dureza (VHN). Se describen también los cuatro tipos de aparatos microscópicos que pueden ser utilizados en dicho método.

X-ray diffraction, thermal analysis, and Raman scattering study of K2BeF4 and comparation to other member of the (beta)-K2SO4 family with ferroelectric -paraelectric transition

Thermal analysis, powder diffraction, and Raman scattering as a function of the temperature were carried out on K2BeF4. Moreover, the crystal structure was determined at 293 K from powder diffraction. The compound shows a transition from Pna21 to Pnam space group at 921 K with a transition enthalpy of 5 kJ/mol. The transition is assumed to be first order because the compound shows metastability. Structurally and spectroscopically the transition is similar to those observed in (NH4)2SO4, which suggests that the low-temperature phase is ferroelectric. In order to confirm it, the spontaneous polarization has been computed using an ionic model.

Raman microprobe characterization of electrodeposited S-rich CuIn(S,Se)2 for photovoltaic applications: Microstructural analysis

This article reports a detailed Raman scattering and microstructural characterization of S-rich CuIn(S,Se)2 absorbers produced by electrodeposition of nanocrystalline CuInSe2 precursors and subsequent reactive annealing under sulfurizing conditions. Surface and in-depth resolved Raman microprobe measurements have been correlated with the analysis of the layers by optical and scanning electron microscopy, x-ray diffraction, and in-depth Auger electron spectroscopy. This has allowed corroboration of the high crystalline quality of the sulfurized layers. The sulfurizing conditions used also lead to the formation of a relatively thick MoS2 intermediate layer between the absorber and the Mo back contact. The analysis of the absorbers has also allowed identification of the presence of In-rich secondary phases, which are likely related to the coexistence in the electrodeposited precursors of ordered vacancy compound domains with the main chalcopyrite phase, in spite of the Cu-rich conditions used in the growth. This points out the higher complexity of the electrodeposition and sulfurization processes in relation to those based in vacuum deposition techniques.

Raman scattering and photoluminescence analysis of silicon on insulator structures obtained by single and multiple oxygen implants

An analysis of silicon on insulator structures obtained by single and multiple implants by means of Raman scattering and photoluminescence spectroscopy is reported. The Raman spectra obtained with different excitation powers and wavelengths indicate the presence of a tensile strain in the top silicon layer of the structures. The comparison between the spectra measured in both kinds of samples points out the existence in the multiple implant material of a lower strain for a penetration depth about 300 nm and a higher strain for higher penetration depths. These results have been correlated with transmission electron microscopy observations, which have allowed to associate the higher strain to the presence of SiO2 precipitates in the top silicon layer, close to the buried oxide. The found lower strain is in agreement with the better quality expected for this material, which is corroborated by the photoluminescence data.

Measurement and simulation of anisotropy in the Infrared and Raman spectra of beta-FeSi2 single crystals

In this paper we show that the orthorhombic phase of FeSi2 (stable at room temperature) displays a sizable anisotropy in the infrared spectra, with minor effects in the Raman data too. This fact is not trivial at all, since the crystal structure corresponds to a moderate distortion of the fluorite symmetry. Our analysis is carried out on small single crystals grown by flux transport, through polarization-resolved far-infrared reflectivity and Raman measurements. Their interpretation has been obtained by means of the simulated spectra with tight-binding molecular dynamics.

Raman scattering of InSb quantum dots grown on InP substrates

In this paper we present the Raman scattering of self-assembled InSb dots grown on (001) oriented InP substrates. The samples were grown by pulsed molecular beam epitaxy mode. Two types of samples have been investigated. In one type the InSb dots were capped with 200 monolayers of InP; in the other type no capping was deposited after the InSb dot formation. We observe two peaks in the Raman spectra of the uncapped dot, while only one peak is observed in the Raman spectra of the capped dots. In the case of the uncapped dots the peaks are attributed to LO-like and TO-like vibration of completely relaxed InSb dots, in agreement with high resolution transmission electron microscopy photographs. The Raman spectra of the capped dot suggest a different strain state in the dot due to the capping layer.

Raman microstructural analysis of silicon-on-insulator formed by high dose oxygen ion implantation: As-implanted structures

A microstructural analysis of silicon-on-insulator samples obtained by high dose oxygen ion implantation was performed by Raman scattering. The samples analyzed were obtained under different conditions thus leading to different concentrations of defects in the top Si layer. The samples were implanted with the surface covered with SiO2 capping layers of different thicknesses. The spectra measured from the as-implanted samples were fitted to a correlation length model taking into account the possible presence of stress effects in the spectra. This allowed quantification of both disorder effects, which are determined by structural defects, and residual stress in the top Si layer before annealing. These data were correlated to the density of dislocations remaining in the layer after annealing. The analysis performed corroborates the existence of two mechanisms that generate defects in the top Si layer that are related to surface conditions during implantation and the proximity of the top Si/buried oxide layer interface to the surface before annealing.