In the present research, a novel method, namely sol-gel/laser-induced technique (SGLIT), has been developed to generate nano-structured TiO2-based films. The TiO2 films based on unloaded (pure) TiO2, Ce-TiO2, W-TiO2 and Ag-TiO2, have been investigated in attempt to stabilise the formation of anatase and consequently of enhancing photo-catalytic and anti-bacterial activities. The TiO2 precursor loaded with Ce2+, W6+ and Ag2+ ions (Ce-TiO2, W-TiO2 and Ag-TiO2) were separately prepared by sol-gel method and spin-coated on microscopic glass slides. A pulsed KrF excimer laser with a wavelength of 248 nm and pulse width of 13-20 ns was employed to irradiate on the sol-gel prepared films at various operating parameters, in terms of laser fluence, number of laser pulses and repetition rate. The work has been focussed on microstructural characterisation of various films prepared by both SGLIT and furnace, in the consideration of crystallographic structure, phase transformation, crystallite sizes, surface morphology, film thickness and optical properties, by means of Raman spectroscopy, XRD, FEG-SEM/EDX, TEM/HR-TEM/EDX, AFM and UV-Vis spectroscopy etc. The results showed that nano-crystallisation of the films after laser irradiation has been achieved, with controllable amount of anatase formation. These coatings presented a unique feature of surface morphology with meso-porosity and much enlarged surface areas, compared with the films prepared by furnace sintering technique. The addition of Ce and Ag, stabilized the anatase structure during the laser irradiations, whereas the addition of W destabilized the anatase structure. The Ce-TiO2 films prepared by SGLIT exhibited anatase structure which was stable up to 500 laser pulses at 35 mJ cm-2 fluence. The anatase was formed after 10 laser pulses only at 65-75 mJ cm-2 fluence in the W-TiO2 films. When a higher number of laser pulses, fluence or higher W6+ loading were chosen, rutile structure started to form. On the other hand, the Ag-TiO2 nano-composite films prepared by SGLIT presented the anatase up to 200 laser pulses at 85 mJ cm-2 fluence. On average, anatase crystallite size of about 38 nm was achieved from both the W-TiO2 and Ag-TiO2 films prepared by SGLIT. In contrast, the furnace-sintered W-TiO2 and Ag-TiO2 films produced anatase crystallite size of 49.4 nm and 29.8 nm respectively. Another achievement of the present research is the development of a single-step laser irradiation technique to generate an Ag-TiO2 nano-composite film on the glass substrate. A pulsed laser beam produced hexagonal Ag nanoparticles along with the crystallization of anatase-based nano-structured TiO2 film which was accomplished in 1 µs only. The films prepared by SGLIT displayed a higher photo-absorption compared to their furnace-sintered counterparts due to the unique surface features with a higher surface roughness. Overall, an enhanced bactericidal activity against E. coli cells was demonstrated under UV light by each of the W-TiO2 films compared to furnace-sintered films except the 1W-TiO2. The E. coli cells did not survive on the W-TiO2 films prepared by SGLIT, after 80 minutes under UV (365 nm) light. In contrast, E. coli cells still survived on the surface of furnace-sintered W-TiO2 films under the same conditions. Ag-TiO2 nano-composite films prepared by SGLIT, demonstrated an enhanced anti-bacterial activity against E. coli compared to the conventionally- made Ag-TiO2 films. No bacteria survived on the Ag-TiO2 films prepared by 50 laser pulses at 85 mJ cm-2 fluence, whereas E. coli colonies always survived on the furnace-sintered Ag-TiO2 films under the UV, natural light and the dark room conditions.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-04-20T18:45:25Z No. of bitstreams: 2 Dissertaçao - Leandro Rezende Franco- 2016.pdf: 12911790 bytes, checksum: 424add978f6ebc12f99143d7bb1c924f (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-04-25T14:29:50Z (GMT) No. of bitstreams: 2 Dissertaçao - Leandro Rezende Franco- 2016.pdf: 12911790 bytes, checksum: 424add978f6ebc12f99143d7bb1c924f (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) / Made available in DSpace on 2016-04-25T14:29:50Z (GMT). No. of bitstreams: 2 Dissertaçao - Leandro Rezende Franco- 2016.pdf: 12911790 bytes, checksum: 424add978f6ebc12f99143d7bb1c924f (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The combined use of the Sequential QM/MM method with the ASEC mean field approximation [1] and the Free Energy Gradient method [2] has been very successful in describing the electronic structure of molecules in solution [3]. The advantage of this combination is that it permits the usage of an atomic- level modeling of the whole system, in contrast to continuum models, and, at the same time, it is less computationally expensive than ab initio or QM/MM simulations, even allowing the employment of more sophisticated electronic structure methods. In this context, the present work deals with the study of conformational and electronic structure, in solvent medium, of two organic compounds, DMACA and Phenol Blue, which have in common the characteristic of having acceptor-donor groups. The study is conducted in the presence of nonpolar, polar protic and polar aprotic solvents. It is adopted as basic methodology the ASEC-FEG, but also it is made a study with a continuum method, namely PCM. The results show that the solvent effect causes a significant geometric distortion of the molecules of interest while causing an internal charge displacement from donor group to acceptor group. Both effects are more pronounced in protic and aprotic solvents but mainly in protic solvents, in which hydrogen bonds lead to a greater solute polarization. The absorption spectra of these molecules, calculated by TD-DFT (CAM-B3LYP), directly reflect these changes. For all solvents, the absolute values of electronic transitions and their respective solvatochromic shifts are in good agreement with the experimental results. / O uso combinado de métodos QM/MM sequencial com uma aproximação de campo médio (ASEC) [1] e o método do Gradiente de Energia Livre [2] tem tido sucesso na descrição da estrutura eletrônica de moléculas em solução [3]. Uma das vantagens dessa combinação é que ela permite o tratamento do sistema soluto-solvente em um nível atomístico, em contraste com modelos contínuos, e tem a vantagem de, ao mesmo tempo, ser uma metodologia menos cara computacionalmente do que simulações QM/MM ab initio [4]. Nesse contexto, o presente trabalho versa sobre o estudo da estrutura conformacional e eletrônica, em meio, de dois compostos orgânicos, DMACA e Phenol Blue, que tem em comum a característica de possuir grupos aceitador e doador de elétrons. O estudo é realizado na presença de solventes apolares, polares apróticos e polares próticos. Adota-se como metodologia básica o método QM/MM sequencial utilizando o ASEC, mas faz-se também um estudo com um método contínuo conhecido, o PCM. Os resultados mostram que o efeito de solvente provoca uma signifativa reestruturação geométrica das moléculas de interesse, ao mesmo tempo em que causa um deslocamento interno de carga do grupo doador para o grupo aceitador. Os dois efeitos são mais pronuciados em solventes apróticos e próticos, mas principalmente nos solventes próticos, em que as ligações de hidrogênio levam a uma maior polarização do soluto. Essas mudanças refletem diretamente no espectro de absorção, calculado por TD-DFT (CAM-B3LYP), dessas moléculas. Dos meios apolares, passando pelos polares apróticos, indo até os polares próticos, os valores absolutos das transições eletrônicas e seus respectivos deslocamentos solvatocrômicos encontram-se em bom acordo com os resultados experimentais.

Made available in DSpace on 2017-07-21T20:43:46Z (GMT). No. of bitstreams: 1 Jean Cleber Bertoni.pdf: 7862049 bytes, checksum: 4c77f7ebc3fc211aac8ad8a7de58ccad (MD5) Previous issue date: 2015-01-30 / There are currently extensive research on aluminum alloys, mainly due to its wide application in the automotive and aerospace industries, due to the following characteristics, among them, low density, high thermal conductivity and high corrosion resistance at room temperature. Al-Fe alloys have a high degree of microstructural change due to changes in their properties when appropriate techniques are applied. The Al-Fe alloy was studied in the composition of 1.5% Fe by weight, which was subjected to the treatment laser surface remelting in order to enhance its surface characteristics. The characterization of these alloys in order to determine the variation of the chemical composition at different depths was performed by Grazzing incidence x-ray diffraction (GIXRD). In this technique, the angle of incidence of the X-ray beam was fixed and the detector moved in 2θ, it is possible to obtain the XRD patterns at different depths by varying the angle of incidence. In this work, the characterizations the micro and nano structural sample of alloy Al-1.5wt.%Fe treated by laser surface remelting (LSR) were performed, on the treated surface, as well as the transverse section, this study was performed at treated samples surface and at the isolated weld fillet on samples, where were applied laser beam speeds of 20, 40 and 60 mm / s. In this study we used different characterization techniques, such as, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, together with atomic force microscopy, and the Vickers hardness. Also in this work the technique of GIXRD was used to obtain depth profiles of near the surface chemical composition of the alloy. The analysis was performed in the micrometer range varying the angle of incidence between 0.5° to 6° in steps of 0.5° and analysis with incident angles 3° and 6° in steps of 0.02° for each 10 sec. As a result by examining the microstructure was characterized melted zone, the heat affected zone and the substrate, a particular features were found for each velocity of the laser beam, generally the treated area showed a more homogenous microstructure consisting of grains smaller feature, with low roughness and high hardness. The heat affected zone was more notorious the morphology of grains elongated feature in the treated and untreated interface for low laser beam scanning velocities. By means of the technique of X-ray diffraction various metastable phases were found, such as aluminum oxide, nitrides, etc., with different intensities of peaks as a consequence of the variation of angle of incidence. / Atualmente há uma ampla investigação sobre ligas de alumínio, principalmente devido a sua larga aplicação na indústria automotiva e aeroespacial, devido as seguintes características, entre elas, a baixa densidade, alta condutividade térmica e elevada resistência à corrosão a temperatura ambiente. Ligas de Al-Fe possuem um alto grau de modificação microestrutural, devido a mudanças em suas propriedades quando técnicas adequadas forem aplicadas. A liga Al-Fe foi estudada na composição de 1,5% de Fe em peso, a qual foi submetida ao tratamento de refusão superficial a laser de modo a aprimorar suas características superficiais. A caracterização dessas ligas com a finalidade de determinar à variação de composição química em diferentes profundidades foi realizado mediante a difração de raios X com ângulo de incidência rasante (DRXIR). Nesta técnica, o ângulo de incidência do feixe de raios X foi fixado e o detector moveu-se em 2θ, sendo possível obter os difratogramas em diferentes profundidades com a variação do ângulo de incidência. Neste trabalho, as caracterizações a nível micro e nano estrutural das amostras da liga Al-1,5%Fe tratadas por refusão superficial a laser (RSL) foram realizadas, tanto na superfície tratada e bem como na parte transversal, este estudo foi realizado nas amostras tratadas em toda a superfície, quanto nas amostras com trilhas isoladas que foram aplicadas as velocidades de feixe laser de 20, 40 e 60 mm/s. Para isso foram utilizados diferentes técnicas de caracterização, tais como, microscópio ótico, microscópio eletrônico de varredura, espectroscopia por energia dispersiva, acompanhada da microscopia de força atômica, bem como da microdureza Vickers. Também neste trabalho a técnica de DRXIR foi utilizada para obtenção de perfis de profundidade da composição química próxima à superfície da liga. A análise foi realizada em escala micrométrica por meio da variação do ângulo de incidência entre 0,5° a 6° com passos de 0,5°, bem como as análises com ângulos incidentes de 3º e 6º com passos de 0,02º a cada 10 s. Como resultado mediante o estudo microestrutural foram caracterizados a zona fundida, a zona afetada termicamente e o substrato, sendo encontradas características particulares para cada velocidade do feixe de laser, de modo geral a zona tratada mostrou ter uma característica microestrutural mais homogênea formada por grãos menores, com baixa rugosidade e de alta dureza. A zona afetada termicamente mostrou ser mais notória a morfologia de grãos com característica alongada na interface tratada e não tratada para baixas velocidades de varredura do feixe laser. Por meio da técnica de difração de raios X diferentes fases metaestáveis foram encontradas, tais como, óxido de alumínio, nitretos, etc, com diferentes intensidades de picos como consequência da variação do ângulo de incidência.

Syftet med denna studie är att analysera ett begränsat antal bilderböcker från två tidsepoker och undersöka hur det icke-verbala gestaltas i dessa bilderböcker och om det gestaltas olika i de två tidsepokerna.  Jag kommer att fokusera mer ingående på konflikter mellan barn, konflikter mellan pedagoger och barn och pedagogers attityder i konflikter och deras sätt att hantera dem. Metoden jag använder mig av i denna studie är en kvalitativ litteraturanalys där jag utgår från Nikolajevas (2000) bok om bilderboksanalys. Tillsammans med relevant litteratur och Howard Garders teori om de sju intelligenserna med fokus på det kroppsliga har jag kommit fram till resultatet att alla böcker oavsett tidsepok via kroppsspråket i böckerna förmedlar att förskolan är något roligt och intressant. Största skillnaden mellan böckerna från de olika tidsepokerna var att i de äldre böckerna visades endast att man inte fick säga emot de vuxna med en tydlig didaktisk underton. I böckerna från 2000-talet gestaltades kroppsspråket så att man förstod det som att barnen hade mer inflytande och behövde inte alltid godta vad de vuxna sa, utan kunde ha mer egen vilja. / The purpose of this study is to analyze a limited number of picture books from two eras and examine how non-verbal portrayed in the picture, and if it is portrayed differently in the two epochs. I will focus in more detail on the conflicts between children, conflicts between educators and children and teachers' attitudes in the conflict and their way of dealing with them. The method I use in this study is a qualitative literature analysis which I assume Nicholas Eve (2000) book on picture analysis. Together with the relevant literature and Howard Gardners theory of the seven intelligences with a focus on the bodily, I have come to the result that all books regardless of era through body language in the books convey to preschool is something fun and interesting. The biggest difference between the books from the different time epochs was that in the older books appeared only that you could not argue with adults with a clear didactic undertone. In the books from the 2000's figure was the body language illustrated in such a way that the reader understands that the children are allowed to have more influence and not necessarily need to accept the opinions and wishes of the adults, since they are entitled to their own opinion and to have their own free will.