xiv, 138 p. : ill. (some col.) / In this dissertation, we demonstrate the generation of optical Raman frequency combs by a single laser pump pulse traveling in hydrogen-filled hollow-core optical fibers. This comb generation process is a cascaded stimulated Raman scattering effect, where higher-order sidebands are produced by lower orders scattered from hydrogen molecules. We observe more than 4 vibrational and 20 rotational Raman sidebands in the comb. They span more than three octaves in optical wavelength, largely thanks to the broadband transmission property of the fiber. We found that there are phase correlations between the generated Raman comb sidebands (spectral lines), although their phases are fluctuating from one pump pulse to another due to the inherit spontaneous initiation of Raman scattering. In the experiment, we generated two Raman combs independently from two fibers and simultaneously observed the single-shot interferences between Stokes and anti-Stokes components from the two fibers. The experimental results clearly showed the strong phase anti-correlation between first-order side bands. We also developed a quantum theory to describe this Raman comb generation process, and it predicts and explains the phase correlations we observe. The phase correlation that we found in optical Raman combs may allow us to synthesize single-cycle optical pulse trains, creating attosecond pulses. However, the vacuum fluctuation in stimulated Raman scattering will result in the fluctuation of carrier envelope phase of the pulse trains. We propose that we can stabilize the comb by simultaneously injecting an auxiliary optical beam, mutually coherent with the main Raman pump laser pulse, which is resonant with the third anti-Stokes field. / Committee in Charge: Dr. Steven van Enk, Chair; Dr. Michael G. Raymer; Dr. Daniel A. Steck; Dr. David M. Strom; Dr. Andrew H. Marcus

Orientador: Carlos José Leopoldo Constantino / Banca: Neri Alves / Banca: Osvaldo Novais de Oliveira Júnior / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: O principal objetivo deste trabalho de mestrado foi a obtenção e caracterização estrutural de um material com propriedades físico-químicas compatíveis com aquelas requeridas por um biomaterial. Filmes contendo diferentes volumes de látex de borracha natural em uma massa fixa de poli(fluoreto de vinilideno) (PVDF), na forma de pó foram fabricados por compressão/aquecimento de uma mistura de ambos os materiais sem o uso de qualquer solvente. Este é um fator importante considerando o uso destes filmes no futuro próximo como biomateriais em diferentes aplicações (indução do crescimento do tecido ósseo, por exemplo), uma vez que os solventes convencionais usados para dissolver o PVDF têm se mostrado tóxicos ao organismo humano. Os filmes foram submetidos a um tratamento via descarga corona de forma que amostras com e sem tal tratamento foram caracterizadas através das técnicas de espectroscopia vibracional via espalhamento Raman e absorção no infravermelho (FTIR), análise térmica via termogravimetria (TG), calorimetria exploratória diferencial (DSC) e análise dinâmico-mecânica (DMA) e microscopias ótica e eletrônica (MEV). As medidas termomecânicas mostraram que os filmes obtidos possuem características mecânicas similares àquelas encontradas no osso humano e boa estabilidade térmica considerando-se a aplicação desejada. As medidas via espectroscopia vibracional indicaram que o PVDF e o látex não interagem quimicamente, compondo uma blenda polimérica. Além disto, os resultados obtidos via micro-Raman mostraram que o aumento da quantidade de látex na blenda permite uma melhor dispersão deste látex na matriz de PVDF quando da produção dos filmes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The main goal of this work was to obtain and characterize structurally a material with physical-chemical properties compatible with those required for a biomaterial. Films containing different volumes of latex of natural rubber in a fixed mass of poly (vinylidene fluoride) (PVDF) powder were fabricated by compressing/annealing a mixture of both materials without using any solvent. This is an important issue having in mind to use these films in the future as biomaterials in different applications (growing of the bone tissue, for instance) once the solvents used to dissolve the PVDF are toxic to human being. The films were submitted to a corona discharge treatment in a way that samples with and without such treatment were characterized using micro-Raman scattering and Fourier transform infrared absorption (FTIR) spectroscopies, thermo-mechanical techniques using thermogravimetry (TG), differential scanning calorimetry (DSC) and dynamical-mechanical analysis (DMA) and optical and scanning electron microscopies (SEM). The thermo-mechanical measurements revealed that the films present mechanical properties close to that found for the human bone and high thermal stability considering the desired applications. The vibrational spectroscopies showed that the latex and PVDF do not interact chemically leading to the formation of a polymeric blend. Besides, the results recorded using the micro-Raman technique revealed that the higher the amount of latex in the blend, the better the miscibility between both materials. In terms of morphology, the blend surface is formed by two domains: one is rougher and contains the latex well dispersed into the PVDF matrix while the other is smoother and contains both materials as well but in a less homogeneous dispersion. However, as the volume of latex is increased from 0.3 to 1.0 mL, the smoother domains become rarer to be found... (Complete abstract, click electronic address below) / Mestre

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-07-17T13:08:15Z No. of bitstreams: 1 CarlenePaulaSilvaDeFarias_TESE.pdf: 2687014 bytes, checksum: a677490ff19b9514e32959228d355d32 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-07-18T14:15:39Z (GMT) No. of bitstreams: 1 CarlenePaulaSilvaDeFarias_TESE.pdf: 2687014 bytes, checksum: a677490ff19b9514e32959228d355d32 (MD5) / Made available in DSpace on 2017-07-18T14:15:39Z (GMT). No. of bitstreams: 1 CarlenePaulaSilvaDeFarias_TESE.pdf: 2687014 bytes, checksum: a677490ff19b9514e32959228d355d32 (MD5) Previous issue date: 2017-04-10 / The main objective of this thesis is to investigate the competing ordered phases in the metallic heavy fermion compound URu2Si2, which displays a bodycentered tetragonal lattice. We first provide a study case of the competition between antiferromagnetic (AF) and spin liquid phases. The antiferromagnetic state is study with spin-wave theory. Whereas the spin liquid analysis has been carried out in an algebraic spin liquid representation. In the second part, we describe an effective theory for Raman scattering experiments at these particular phases. We provide insight about the hidden order phase displayed by the heavy fermion compound URu2Si2. / L?objectif central de cette th?se est d??tudier des phases ordonn?es en comp?tition dans des mat?riaux magn?tiques pr?sentant une structure cristalline t?tragonale centr?e. Ce travail est divis? en deux parties principales. Dans la premi?re, nous pr?sentons les r?sultats de notre ?tude de la comp?tition entre des ?tats ordonn?s antiferromagn?tiques et des phases liquides de spin. Nous montrons comment ces derni?res peuvent ?tre stabilis?es par la frustration g?om?trique et par une g?n?ralisation de la sym?trie de spin au groupe SU(n). Les ?tats antiferromagn?tiques sont d?crits par une th?orie d?onde de spin et l?analyse de liquide de spin est effectu?e par une repr?sentation fermionique des op?rateurs de spin. Dans la deuxi?me partie, nous d?crivons une th?orie effective pour d?rcrire des exp?riences de diffusion Raman. Nous fournissons un aper?u de la phase d?ordre cach? affich?e par le compos? de fermions lourds URu2Si2.

Made available in DSpace on 2016-08-18T18:19:30Z (GMT). No. of bitstreams: 1 Dissertacao Girlane.pdf: 2233662 bytes, checksum: e187d35550c694d6e69d8bc6b2ca20db (MD5) Previous issue date: 2011-09-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Raman scattering phenomena has far been widely used as an experimental methodology for probing materials properties. In the last decade, the combination of microscopy and spectroscopy aspects has been largely used in the study of materials in low dimensions, especially carbon nanotubes and graphene. Graphene is a two-dimensional material that has one hexagonal structure. Due to its excellent crystalline quality, this material has shown great prospects of strategic applications in the near future. The majority of the studies reported on graphene are carried out by using confocal microscopes, which relies on the longitudinal chromatic aberration. This optical effect is related to intrinsic limitation of any lens to focus light with different wavelength at the same focal plane. In this work, we examine the effect of longitudinal chromatic aberration and also the effect of irradiance on the Raman spectra of graphene. Consistent with the results of literature, we found that the intensity of the Raman signal for the G mode increases linearly with the number of layers, up to the limit of six layers identified in our samples. We also found a strong dependence of the Raman intensity with longitudinal chromatic aberration. Owing to this effect, the intensity of the G peak was underestimated in about 20%, while the intensity of G peak appeared 56% below the real value. Measurement performed to confirm the effect of longitudinal chromatic aberration showed an aberration of 1,8 μm/eV for Raman scattering and 2,0 μm/eV by using pure reflectometry. Measurements in graphene with defects revealed a strong dependence of peak frequency with focal position and laser power as well. Changes of 6 cm-1 in G' mode was observed for laser power between 44 e 175 μW. / A microscopia Raman é uma das técnicas experimentais mais versáteis e tem sido muito utilizada no estudo das propriedades físicas de materiais. A microscopia confocal em combinação com a espectroscopia Raman tem levado a obtenção de imagens de estruturas em escala nanométrica. Estas ferramentas conjugadas têm sido amplamente utilizadas no estudo de propriedades de materiais em baixas dimensões, como nanotubos de carbono e grafeno. O grafeno é um material bidimensional que possui uma estrutura hexagonal. Devido à sua excelente qualidade cristalina, esse material tem apresentado grandes perspectivas de aplicações estratégicas no futuro próximo. Neste trabalho foram discutidos os efeitos da aberração cromática longitudinal e o efeito da irradiância sobre espectros Raman do grafeno obtidos por um microscópio Raman confocal. Consistente com os resultados da literatura, a intensidade do sinal Raman para o modo G aumentou linearmente com o número de camadas, até o limite de 6 camadas identificadas nas nossas amostras. Os resultados obtidos mostraram forte dependência da intensidade do sinal com a aberração cromática longitudinal. Por causa deste efeito, a intensidade do pico G foi subavaliada em cerca de 20%, enquanto a intensidade do pico G foi subavaliada em aproximadamente 56%. Medidas realizadas para confirmar o efeito da aberração cromática longitudinal mostraram uma aberração de 1,8 μm/eV para o espalhamento Raman e 2,0 μm/eV para o espalhamento Rayleigh. Medidas em grafeno com defeitos revelaram a grande dependência na posição dos picos com posição focal ou com a potência do laser. Mudanças de 6 cm-1 no modo G foram observadas para potências entre 44 e 175 μW.

Durante os últimos cinco anos, a nanotecnologia tem atingido avanços significativos em diversas áreas da ciência e tecnologia. Um dos assuntos que está sendo intensamente estudado pela comunidade científica é a intensificação de campo próximo (hot spot) que pode ser aplicada em dispositivos sensores com capacidade de detecção de apenas uma molécula e em nano-antenas ópticas aplicadas na fabricação de dispositivos plasmônicos. Neste sentido, as principais contribuições da presente tese são processos de fabricação de nanoestruturas metálicas e de silício e o estudo da intensificação de campo próximo denominada de pontos quentes (hot spots) nestas estruturas. As nanoestruturas metálicas de Au (ouro) foram obtidas a partir do processo de auto-organização de esferas de poliestireno. As esferas de poliestireno serviram como camada sacrificial (molde) para a obtenção de nanoestruturas metálicas organizadas. Sobre as estruturas de Au organizadas foram depositadas moléculas de cristal violeta para serem utilizadas como moléculas de prova (sondas) no monitoramento da existência dos pontos quentes com o auxílio do espalhamento Raman das moléculas. As nanoestruturas de Au possibilitaram uma intensificação do espalhamento Raman devido à intensificação do campo próximo na superfície metálica periódica de Au. As nanoestruturas e microestruturas de silício foram obtidas a partir da tecnologia de silício poroso. As propriedades do silício poroso foram moduladas através da implantação de íons de hidrogênio (H +) que possibilitou a formação de silício microporoso com forte emissão fotoluminescente (PL) e intensificação do espalhamento Raman superficial devido ao fenômeno de Raman ressonante. Sobre as estruturas macroporosas de silício foram adsorvidas moléculas de azul de metileno para serem utilizadas como moléculas de prova para monitoramento da intensificação do campo próximo e do efeito SERS no silício. A obtenção da intensificação de campo próximo em silício é uma contribuição completamente inédita, pois este fenômeno devia-se, até o momento, somente a materiais metálicos (nanoestruturas metálicas), mostrando sua existência também no silício. / During the last five years, nanotechnology has achieved significant progress in several areas of science and technology. One of the issues that are being intensively studied by the scientific community is the intensification of near-field (hot spot) that can be applied to devices with sensors capable of detecting a single molecule and nano-optical antennas used in the fabrication of plasmonic devices. In this sense, the main contributions of this thesis are processes for manufacture of metal and silicon nanostructures and the study of near-field intensification called hot spots in these structures. The metal nanostructures of Au (gold) were obtained from the process of self-assembling of polystyrene beads. The polystyrene beads were used as sacrificial layer (mold) for obtaining organized metallic nanostructures. On the structures of organized Au were deposited molecules of violet crystal to be used as proof of molecules (probes) to monitor the existence of hot spots with the help of Raman scattering of molecules. The Au nanostructures allowed an intensification of the Raman scattering due to the intensification of the near-field in the periodic Au surface. The microstructures and nanostructures of silicon were obtained using the porous silicon technology. The properties of porous silicon were modulated by the implantation of hydrogen ions (H +) that allowed the formation of microporous silicon which showed high photoluminescence emission (PL) and Raman scattering intensification of the surface due to the phenomenon of resonant Raman. Methylene blue molecules were adsorbed on the macroporous silicon structures to be used as probe molecule for the monitoring of near-field intensification and the SERS effect in silicon. The obtaining of near-field intensification in silicon is an entirely unprecedented contribution, because this phenomenon had been observed, so far, only on the metallic materials (metal nanostructures), showing its existence in the silicon too.

Orientador: Pedro Antonio Muniz Vazquez / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-23T04:27:58Z (GMT). No. of bitstreams: 1 Khan_Alamgir_D.pdf: 2306325 bytes, checksum: a39e71c04424c25645e57f5fe0ab453c (MD5) Previous issue date: 2013 / Resumo: Neste trabalho novas metodologias para cálculo das intensidades Raman absolutas de moléculas na fase gasosa foram desenvolvidas para uma série de moléculas pequenas, usando o método ab initio (CCSD) e a teoria do funcional de Densidade (DFT) (PBE0, LB94 e CAM-B3LYP) dentro da Teoria de Polarizabilidade de Placzek. A velocidade em cálculo junto com economia nos recursos computacionais foram estudadas usando dos conjuntos de bases polarizadas (potential efetivo de caroço) pSBKJC e pStuttgart desenvolvidos pelo nosso grupo através do procedimento "polarização eléctrica de Sadlej". Os resultados da metodolgia proposta em comparação com conjunto de bases Sadlej-pVTZ como referência, em níveis CCSD e DFT mostram acordos quantitativos nas propriedades e uma redução no tempo computacional. Na segunda parte deste trabalho, estas metodologias foram aplicadas para uma série de moléculas grandes de pesticidas organoclorados, ou seja; DDT e cinco análogos estruturas e de cinco pesticidas que contêm o grupo norborneno, utilizando métodos DFT (PBE0 e CAMB3LYP) para o cálculo das propriedades Raman. O conjunto de bases permitiram a redução o número de elétróns de 6 para 4 para carbono, 8 para 6 para oxigênio, 16 para 6 para o enxofre e 17 para 7 para o cloro. Assim, estas reduções de número de elétrons dá 50% de economia em recursos computacionais e tempo para os cálculos das propriedades ópticas das moléculas estudadas / Abstract: In this work new methodologies for calculating the absolute Raman intensities originating from gas phase molecules were developed for a set of small tests molecules, using ab initio quantum-mehancial (CCSD) and Density functional (PBE0, LB94 and CAMB3LYP functionals) methods within Placzek¿s Polarizability Theory. The speed-up in computation along with economy in the computational resources were studied using a newly polarized effective core potential basis set pSBKJC and pStuttgart developed by our group through Sadlej¿s electric polarization procedure. The results of the proposed methodology in comparison with Sadlej-pVTZ as reference basis set at CCSD and DFT levels show quite a good quantitative agreements in the properties with a valuable reduction in computational time and resources. In the second part of this work, the methodologies being assessed were applied for a series of large Organochlorinated pesticides ou seja, DDT and five structurally related pesticides and of five pesticides containing the Norbornene group, using DFT methods (PBE0 and CAMB3LYP functionals). The basis set allowed the reduction of the number of electrons from 6 to 4 for carbon, 8 to 6 for oxygen, 16 to 6 for sulfur and 17 to 7 for chlorine atoms. Thus, these reductions in electrons give more than 50% of savings in computer resources and time for the calculations of optical properties of reference molecules of environmental interests / Doutorado / Físico-Química / Doutor em Ciências

This thesis is divided into two parts; the first part presents results on the effect of the flow of fluids and electrochemical bias on single walled carbon nanotubes (SWNT). Issues pertaining to the entry of water into the cylindrical pores of the SWNT and its freezing dynamics have also been addressed in the first part of the thesis. The second part of the thesis deals with Raman scattering studies of iron perovskite namely CaFeO3 and La0.33Sr0.67FeO3 across their charge-disproportionation transition temperatures. PART 1 Chapter 1: Introduction This chapter presents an overview of the systems studied in this thesis, i.e., (i) SWNT and (ii) iron perovskite’s containing iron in Fe4+(d4) state, namely CaFeO3 and La0.33Sr0.67FeO3. It also contains an introduction to the two spectroscopic techniques used in the present thesis, namely Raman scattering and Nuclear Magnetic Resonance. A quantum mechanical picture of Raman scattering, in general, and resonance Raman scattering in particular along with a brief introduction to the apparatus used both for the micro Raman and the low temperature experiments is presented in this chapter. A general introduction to Nuclear Magnetic Resonance (NMR) is also given with an emphasis on various interactions leading to the broadening of the NMR absorption linewidths. Chapter 2: Carbon nanotube liquid flow sensors This chapter presents experimental results and theoretical understandings of the generation of electrical signals by flowing polar/ionic liquids over a mat of SWNT. We first present experimental findings that the flow of a variety of liquids on SWNT bundles induces an electrical signal (voltage/current) in the sample along the direction of the flow. The electrical response is found to be a logarithmic function of the flow speed over a wide range. The magnitude of the signal generated depends sensitively on the ionic conductivity and the polar nature of the liquid and weakly on the viscosity of the liquid. Furthermore its direction can be controlled by electrochemical biasing of the nanotubes. The ratio of the open circuit voltage to the short circuit current is found to be governed by the nanotube resistance. These experimental findings are inconsistent with the conventional idea of a streaming potential as the possible cause. Our measurements suggest that the dominant mechanism responsible for this highly sub-linear response should involve a direct forcing of the free charge carriers in the nanotubes by the fluctuating Coulombic field of the liquid flowing past it. Two alternative understandings of the experimental findings are also presented in this chapter. The first mechanism invokes the idea of a “pulsating ratchet” whereby the charge carriers in the nanotubes experience an asymmetric spatial bias because of the shear-induced deformation of the ion-plus-polar atmosphere at the liquid-solid interface temporally modulated by the liquid flow. In addition, we also propose that experimental findings can be understood qualitatively in terms of three interrelated ideas: (a) Induced friction: The fluctuating charge density of the ions close to the nanotube couples coulombically to the charge carriers in the nanotube and, therefore, offers a friction to the motion of these charge carriers (in addition to the Ohmic friction intrinsic to the carbon nanotubes); (b) Flow-induced drag: In virtue of the above frictional coupling, an imposed liquid flow drags the charge carriers along through the nanotube; (c) Reduction of induced friction at high flow speeds: The space-time correlated Coulombic fluctuations, inherent to the liquid electrolyte, are advected by the liquid flow, and thus get Galilean boosted (Doppler shifted) as seen in the mean rest frame of the drifting carriers in the nanotube. This would cause a reduction of the frictional grip to the motion of the charge carriers in the nanotube with increasing flow speed resulting in a sublinear dependence of the charge drift-velocity (electrical response) on the liquid flow speed. With the above in mind, a quantitative derivation of these frictional effects, first from a heuristic argument, and then analytically from a Langevin-equation treatment have been presented. Chapter 3: Direct generation of voltage and current by gas flow over carbon nanotubes and semiconductors Having obtained experimental evidence of the generation of liquid flow induced electrical signals over single-walled carbon nanotubes, it was only natural to look for the same effect by flowing gases over nanotubes. We show here a direct generation of measurable voltages and currents when gas flows at modest speeds of a few meters per second over single-walled carbon nanotubes . Interestingly, unlike the previous effect (generation of voltages by flow of liquids over single-walled carbon nanotubes), this effect is not specific to single-walled carbon nanotubes and occurs for a wide variety of solids, including single and multi-walled carbon nanotubes, doped semiconductors and metals. Moreover, the gas flow induced signals depend quadratically on the gas flow velocities. This is in sharp contrast to the results obtained by flowing liquids over single-walled carbon nanotubes where the liquid flow generated signal was found to be logarithmically dependent on the flow velocities. In this chapter we provide evidence that the underlying mechanism for the gas flow generated electrical signal is an interplay of Bernoulli’s principle and the Seebeck effect: Pressure difference along streamlines gives rise to temperature difference across the sample which, in turn, produces the measured voltage. Chapter 4: Water at nanoscale confined in single-walled carbon nanotubes studied by NMR In this chapter, we seek experimental evidence of the occupancy of water in the cylindrical pores of the nanotubes. Proton NMR studies have been carried out as a function of temperature from 210 K to 300 K of water confined within SWNT. The NMR lineshape at and below the freezing point of bulk water is asymmetric which can be decomposed into a sum of two Lorentzians. The intensities of both the components decrease with lowering of temperature below 273 K, one component L1 vanishing below 242 K and the other component L2 below 217 K. Following the simulations of Koga et al. (Nature, 412, 802, 2001) showing that the radial density profile of confined water in SWNT has a distribution peak at the center which disappears below the freezing temperature, the L1 component is associated with the protons of the water molecules at the center and the L2 component is associated with protons of water molecules associated at a distance ~ 3Å away from the walls of the nanotubes. In this scenario the complete freezing of the water at ~ 212 K is preceded by the withdrawal of the water molecules from the center of the nanotubes. Chapter 5: Electrochemical tuning of band structure of single walled carbon nanotubes probed by in-situ resonance Raman scattering The work presented in this chapter is motivated by the experimental observation that SWNT have excellent actuating properties, i.e, porous sheets of carbon nanotubes were shown to suffer length changes when subjected to electrochemical bias, with action observed up to 1 KHz. The fast response of the nanotube actuator rules out any mechanism related to the intercalation of ions as is applicable to the case of the polymer actuators. This chapter presents results of in-situ resonance Raman scattering of SWNT investigated under electrochemical biasing. The experimental results show that the intensity of the radial breathing mode varies significantly in a non-monotonic manner as a function of the cathodic bias voltage, but does not change appreciably under anodic bias. The tangential mode is, however, not affected. These results can be quantitatively understood in terms of the changes in the energy gaps between the one-dimensional van Hove singularities in the electron density of states arising possibly due to the alterations in the overlap integral of π-bonds between the p-orbitals of adjacent carbon atoms. This chapter also contains results from ab-initio restricted Hartree Fock calculations in a simplistic geometry where a nanotube is surrounded by two concentric rings of ions. The ab-initio calculation results suggest that the dominant contribution to the strain developed in the nanotubes originates from the electrostatic interactions between the ions and the delocalized π electrons as compared to the doping effects. PART 2 Chapter 6: Raman scattering in CaFeO3 and La0.33Sr0.67FeO3 across the charge disproportionation phase transition Temperature dependent micro-Raman studies of orthorhombic CaFeO3 and rhombohedral La0.33Sr0.67FeO3 were carried out with an aim to study the role of phonons in the formation of the charge disproportioned state (Fe4+ → Fe5++Fe3+) below the transition temperature (Tco) of 290 K and 200 K, respectively. Shell model lattice dynamics calculations were performed for CaFeO3 to assign the Raman modes and determine their vibrational pattern. Temperature dependence of the peak positions and peak widths of various modes for both the systems show distinct changes across their respective transition temperatures. In CaFeO3 the symmetric stretching mode at 707 cm−1 splits into two modes, 707 cm−1 and 684 cm−1 . Interestingly, the 707 (684) cm−1 mode appears only in HH(HV) polarization. In comparison, the Raman band at 704 cm−1 in La0.33Sr0.67FeO3 which has been assigned to the Raman forbidden symmetric stretching mode, disappears below Tco. In addition, two modes at 307 cm−1 and 380 cm−1 of La0.33Sr0.67FeO3 approach each other at Tco. Our experiments show that for both the systems, CaFeO3 and La0.33Sr0.67FeO3, the lattice distortion changes across Tco. Chapter 7: Summary and future outlook The last chapter summarizes our main findings reported in the thesis. It also contains possible future studies which are worth pursuing to add further insights in the issues addressed.

Microscopy techniques have been developed and refined over multiple decades, but innovation around single photon modalities has slowed. The advancement of the utility of information acquired, and minimum resolution available is seemingly reaching an asymptote. The fusion of light microscopy and well-studied nonlinear processes has broken through this barrier and enabled the collection of vast amounts of additional information beyond the topographical information relayed by traditional microscopes. Through nonlinear imaging modalities, chemical information can also be extracted from tissue. Nonlinear microscopy also can beat the resolution limit caused by diffraction, and offers up three-dimensional capabilities. The power of nonlinear imaging has been demonstrated by countless research groups, solidifying it as a major player in biomedical imaging. The value of a nonlinear imaging system could be enhanced if a reduction in size would permit the insertion into bodily cavities, as has been demonstrated by linear imaging endoscopes. The miniaturization of single photon imaging devices has led to significant advancements in diagnostics and treatment in the medical field. Much more information can be extracted from a patient if the tissue can be imaged in vivo, a capability that traditional, bulky, table top microscopes cannot offer. The development of new technologies in optics has enabled the miniaturization of many critical components of standard microscopes. It is possible to combine nonlinear techniques with these miniaturized elements into a portable, hand held microscope that can be applied to various facets of the biomedical field. The research demonstrated in this thesis is based on the selection, testing and assembly of several miniaturized optical components for use as a nonlinear imaging device. This thesis is the first demonstration of a fibre delivered, microelectromechanical systems mirror with miniaturized optics housed in a portable, hand held package. Specifically, it is designed for coherent anti-Stokes Raman scattering, second harmonic generation, and two-photon excitation fluorescence imaging. Depending on the modality being exploited, different chemical information can be extracted from the sample being imaged. This miniaturized microscope can be applied to diagnostics and treatments of spinal cord diseases and injuries, atherosclerosis research, cancer tumour identification and a plethora of other biomedical applications. The device that will be revealed in the upcoming text is validated by demonstrating all designed-for nonlinear modalities, and later will be used to perform serialized imaging of myelin of a single specimen over time.

Made available in DSpace on 2016-01-26T18:56:04Z (GMT). No. of bitstreams: 1 Tamiris Garbiatti de Oliveira.pdf: 1606086 bytes, checksum: cf9e26811174e34243865dc9dfffec23 (MD5) Previous issue date: 2015-03-23 / The unlimited use of pesticides, besides contribute with to increase environmental pollution, is also influencing negatively the health of the living beings, including the people health. Many studies show the result these chemicals in the reproductive system of animals and even same at man, can cause infertility problem, which can originate, among other factors, the low sperm quality and quantity. This is study aimed at evaluating human sperm quality parameters and the chemical evaluation of the core of the sperm trough Raman Scaterring Spectroscopy, after in vitro exposure to different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and atrazine. The choice of the use of the these herbicides was because they are widely use throughout the world, especially in Brazil, highlighted the west Paulista region, used at cane sugar plantation, significant culture of the region. In this context, sperm samples were selected according to the normal testing parameters that evaluate sperm quality, such as liquefaction, viscosity, appearance, volume, pH, sperm, vitality, morphology and motility. Semen samples of 10 healthy donor were exposed to study herbicides varying the concentration and time. After the different exposures (0.05, 0.5, 1.0, 5.0 and 125 &#956;g/mL, 30 and 60 min), the analysis of motility and vitality were again evaluated. The Raman Scaterring spectra were obtained from samples control sperm and after exposure to the herbicide 2,4-D e atrazine at concentration of 125 &#956;g/mL and 60 min incubation. The progressive motility and total motility decreased from the concentration 0,5 &#956;g/mL at times 30 and 60 minutes while the percentage of sperm properties increased. The progressive motility and total motility decreased from the concentration 0.5 mg / mL at times 30 and 60 minutes while the percentage of sperm immotile increased. The vitality (viable sperm) decreased significantly (p <0.05) from the exposure concentration 0.5 &#956;g/mL to 2,4-D and from 1.0 &#956;g/mL atrazine, at times 30 and 60 minutes, showing that there is a functional change of trend of human sperm after exposure to these herbicides, and this change is intensified with the exposure time factor and concentration of herbicides. Through the Raman Scaterring technique allowed us to characterize normal human sperm and exposed to herbicides and verify the change in the molecular structure in the exposed sperm, evidenced by changes in relative intensities of the bands 785, 1095, 1255, 1336, 1374, 1486 and 1575 cm-1 treated with 2,4-D and a decrease at 1095 after exposure to atrazine. These results indicate the modification of nitrogenous bases and the phosphate group that make up DNA present in the nucleus of the sperm. / A utilização desenfreada de praguicidas, além de contribuir com o agravamento da poluição ambiental, também está influenciando de forma negativa a saúde dos seres vivos, inclusive a saúde das pessoas. Muitos estudos mostram a interferência desses produtos químicos no sistema reprodutor de animais e até mesmo do homem, podendo acarretar problemas de infertilidade, que podem ser originados, dentre vários fatores, pela baixa quantidade e qualidade espermática. Este estudo visa á avaliação de parâmetros de qualidade espermática humana e a avaliação química do núcleo do espermatozoide, por meio de Espectroscopia de Espalhamento Raman, após a exposição in vitro a diferentes concentrações de ácido 2,4-diclorofenoxiacético (2,4-D) e atrazina. Estes herbicidas são amplamente utilizados em todo o mundo, principalmente no Brasil, em destaque a região do Oeste Paulista, por serem empregados na cana-de-açúcar, cultura significativa da região. Neste contexto, foram selecionadas amostras de espermatozoides de acordo com os parâmetros normais de testes que avaliam a qualidade espermática, como: liquefação, viscosidade, aparência, volume, pH, concentração de espermatozoides, vitalidade, morfologia e motilidade. Amostras de sêmen de 10 doadores saudáveis foram expostas aos herbicidas de estudo, variando o tempo e a concentração. Após as diferentes exposições (0,05; 0,5; 1,0; 5,0 e 125 &#956;g/mL, 30 e 60 min), as análises de motilidade e vitalidade foram novamente avaliadas. Os espectros de Espalhamento Raman foram obtidos das amostras de espermatozoide controle e após a exposição aos herbicidas 2,4-D e atrazina na concentração de 125 µg/mL em 60 min de incubação. A motilidade progressiva e motilidade total diminuíram a partir da concentração 0,5 &#956;g/mL nos tempos 30 e 60 min enquanto que a porcentagem de espermatozoides imóveis aumentou. A vitalidade (espermatozoides viáveis) diminuiu significativamente (p<0,05) a partir da exposição da concentração 0,5 &#956;g/mL para o 2,4-D e a partir de 1,0 &#956;g/mL para a atrazina, nos tempos 30 e 60min, mostrando-se que há uma tendência de alteração funcional do espermatozoide humano após a exposição a estes herbicidas, e esta alteração é intensificada com o fator de tempo de exposição e concentração dos herbicidas testados. Por meio da técnica de Espalhamento Raman foi possível caracterizar o espermatozoide humano normal e os expostos aos herbicidas e verificar a alteração na estrutura molecular nos espermatozoides expostos, evidenciadas pelas alterações nas intensidades relativas das bandas 785, 1095, 1255, 1336, 1374, 1486 e 1575 cm-1 do tratado com 2,4-D, e uma diminuição na banda de 1095 após a exposição à atrazina. Estes resultados indicam a alteração das bases nitrogenadas e do grupo fosfato que compõem o DNA presente no núcleo do espermatozoide.

Made available in DSpace on 2016-07-18T17:46:21Z (GMT). No. of bitstreams: 1 Tamiris Garbiatti de Oliveira.pdf: 1606086 bytes, checksum: cf9e26811174e34243865dc9dfffec23 (MD5) Previous issue date: 2015-03-23 / The unlimited use of pesticides, besides contribute with to increase environmental pollution, is also influencing negatively the health of the living beings, including the people health. Many studies show the result these chemicals in the reproductive system of animals and even same at man, can cause infertility problem, which can originate, among other factors, the low sperm quality and quantity. This is study aimed at evaluating human sperm quality parameters and the chemical evaluation of the core of the sperm trough Raman Scaterring Spectroscopy, after in vitro exposure to different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and atrazine. The choice of the use of the these herbicides was because they are widely use throughout the world, especially in Brazil, highlighted the west Paulista region, used at cane sugar plantation, significant culture of the region. In this context, sperm samples were selected according to the normal testing parameters that evaluate sperm quality, such as liquefaction, viscosity, appearance, volume, pH, sperm, vitality, morphology and motility. Semen samples of 10 healthy donor were exposed to study herbicides varying the concentration and time. After the different exposures (0.05, 0.5, 1.0, 5.0 and 125 &#956;g/mL, 30 and 60 min), the analysis of motility and vitality were again evaluated. The Raman Scaterring spectra were obtained from samples control sperm and after exposure to the herbicide 2,4-D e atrazine at concentration of 125 &#956;g/mL and 60 min incubation. The progressive motility and total motility decreased from the concentration 0,5 &#956;g/mL at times 30 and 60 minutes while the percentage of sperm properties increased. The progressive motility and total motility decreased from the concentration 0.5 mg / mL at times 30 and 60 minutes while the percentage of sperm immotile increased. The vitality (viable sperm) decreased significantly (p <0.05) from the exposure concentration 0.5 &#956;g/mL to 2,4-D and from 1.0 &#956;g/mL atrazine, at times 30 and 60 minutes, showing that there is a functional change of trend of human sperm after exposure to these herbicides, and this change is intensified with the exposure time factor and concentration of herbicides. Through the Raman Scaterring technique allowed us to characterize normal human sperm and exposed to herbicides and verify the change in the molecular structure in the exposed sperm, evidenced by changes in relative intensities of the bands 785, 1095, 1255, 1336, 1374, 1486 and 1575 cm-1 treated with 2,4-D and a decrease at 1095 after exposure to atrazine. These results indicate the modification of nitrogenous bases and the phosphate group that make up DNA present in the nucleus of the sperm. / A utilização desenfreada de praguicidas, além de contribuir com o agravamento da poluição ambiental, também está influenciando de forma negativa a saúde dos seres vivos, inclusive a saúde das pessoas. Muitos estudos mostram a interferência desses produtos químicos no sistema reprodutor de animais e até mesmo do homem, podendo acarretar problemas de infertilidade, que podem ser originados, dentre vários fatores, pela baixa quantidade e qualidade espermática. Este estudo visa á avaliação de parâmetros de qualidade espermática humana e a avaliação química do núcleo do espermatozoide, por meio de Espectroscopia de Espalhamento Raman, após a exposição in vitro a diferentes concentrações de ácido 2,4-diclorofenoxiacético (2,4-D) e atrazina. Estes herbicidas são amplamente utilizados em todo o mundo, principalmente no Brasil, em destaque a região do Oeste Paulista, por serem empregados na cana-de-açúcar, cultura significativa da região. Neste contexto, foram selecionadas amostras de espermatozoides de acordo com os parâmetros normais de testes que avaliam a qualidade espermática, como: liquefação, viscosidade, aparência, volume, pH, concentração de espermatozoides, vitalidade, morfologia e motilidade. Amostras de sêmen de 10 doadores saudáveis foram expostas aos herbicidas de estudo, variando o tempo e a concentração. Após as diferentes exposições (0,05; 0,5; 1,0; 5,0 e 125 &#956;g/mL, 30 e 60 min), as análises de motilidade e vitalidade foram novamente avaliadas. Os espectros de Espalhamento Raman foram obtidos das amostras de espermatozoide controle e após a exposição aos herbicidas 2,4-D e atrazina na concentração de 125 µg/mL em 60 min de incubação. A motilidade progressiva e motilidade total diminuíram a partir da concentração 0,5 &#956;g/mL nos tempos 30 e 60 min enquanto que a porcentagem de espermatozoides imóveis aumentou. A vitalidade (espermatozoides viáveis) diminuiu significativamente (p<0,05) a partir da exposição da concentração 0,5 &#956;g/mL para o 2,4-D e a partir de 1,0 &#956;g/mL para a atrazina, nos tempos 30 e 60min, mostrando-se que há uma tendência de alteração funcional do espermatozoide humano após a exposição a estes herbicidas, e esta alteração é intensificada com o fator de tempo de exposição e concentração dos herbicidas testados. Por meio da técnica de Espalhamento Raman foi possível caracterizar o espermatozoide humano normal e os expostos aos herbicidas e verificar a alteração na estrutura molecular nos espermatozoides expostos, evidenciadas pelas alterações nas intensidades relativas das bandas 785, 1095, 1255, 1336, 1374, 1486 e 1575 cm-1 do tratado com 2,4-D, e uma diminuição na banda de 1095 após a exposição à atrazina. Estes resultados indicam a alteração das bases nitrogenadas e do grupo fosfato que compõem o DNA presente no núcleo do espermatozoide.