7 resultados para Infravermelho médio

em Repositório Institucional da Universidade Estadual de São Paulo - UNESP


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Química - IQ

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Ceramic powders based on Zn3Ga2Ge2O10: Cr3+ X% (X = 0.0; 0.5; 0.75; 1.0) were synthesized by solid-state reaction method. The gallium-zinc germanate doped with chromium presents an interesting property of phosphorescence, that means, it is capable of emitting light when excited by a source of radiation, and such emission remains for some time after stopping the source. For this reason, these materials can be widely applied in night-vision surveillance, (through the use of solar energy, for example), electronic devices screen, emergency routes signals, control panels indicators in dark environments, etc. In this job were considered different amounts of dopant in order to perform a comparison of structural and photoluminescent properties. For that, some analyses were performed on samples, such as XRD, FT-Raman, SEM, UV-vis and photoluminescence measurements (PL). Such analysis allowed to infer that the presence of chromium results in no phase transformation, so that the four compositions have the same set of phases: cubic, rhombohedral and hexagonal. Although the structure was not changed, chromium influences other properties / characteristics of these materials. Examples are: increase of band-gap, decrease of average particle size, small changes in binding energy checked by Raman and especially the increase of photoluminescent property. The chromium ions have great ease in replacing gallium ions in octahedral sites, resulting in emission of light with a wavelength of about 700 nm (infrared region), which is justified by the spin-forbidden 2E 4A2 transition. In other words, chromium is a favorable luminescent center, acting as a trap in the crystal structure, since it imprisons the excitation energy easily and releases it gradually, allowing the phosphorescence. It was observed that the composition ... (Complete abastract click electronic access below)

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Against the current need of improvements in construction processes and increased competitiveness on Construction Industry in Brazil, lean construction concepts have spread all over the market, achieving small and medium enterprises. In reason of this, the monograph it is a research based on interviews of small and medium construction enterprises from Vale do Paraíba, São Paulo, Brazil, that focus in identify practices of lean construction implementation and barriers to incorporate these concepts on them. Besides the research, it will be done an analysis and some suggestions to overcome the obstacles appeared

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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This qualitative nature of work was developed with the participation of a group of students enrolled in the first year of high school from a public school of the state of São Paulo, in the city of Taubaté. Their goal was to determine how students deal with geometry tasks in investigative classes. To guide this research was drawn up the following question: As students of the first year of high school express their knowledge of building triangles and quads in classes of investigative activities?. The choice of investigative nature of this activity occurred by enhancing student participation and thus generate a greater chance of it not be guided only by what the teacher wants, but by his own curiosity and using their own tools for this. In the data analysis process stands out the interest generated in students for this type of activity and posture maintained throughout the work, mobilizing their expertise to answer the questions posed