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1
Lata, Elisabeth. "L’isoforme embryonnaire de l’ARN polymérase III humaine : son rôle dans la transformation tumorale et l’établissement de métastases". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0168.
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L'ARN polymérase (Pol) III transcrit des petits ARN non-codants qui sont essentiels pour la cellule. Chez la plupart des vertébrés, il existe deux isoformes de la Pol III selon l’incorporation de la sous-unité RPC7α ou RPC7β. Alors que RPC7β est ubiquitaire, RPC7α est exprimée dans les cellules souches embryonnaires et certaines cellules tumorales. En particulier, RPC7α est surexprimée dans des échantillons cliniques et des lignées cellulaires de cancer du sein triple négatif (CSTN). La suppression de RPC7α dans la lignée CSTN MDA-MB-231 inhibe la croissance tumorale et la formation de métastases dans un modèle murin de xénogreffe. Cependant, les mécanismes moléculaires par lesquels la Pol IIIα régule la tumorigenèse et les métastases sont encore inconnus. Dans cette thèse, je montre que la suppression de RPC7α dans les cellules MDA-MB-231 modifie l'expression de plusieurs ARN messagers dont certains impliqués dans la régulation du cancer et de l’expression des gènes. L’analyse de la localisation de RPC7α indique qu’en plus de son occupation de gènes Pol III, elle est également colocalisée sur des gènes codants avec la Pol II. Ces gènes sont parmi les plus exprimés dans les cellules MDA-MB-231 et sont impliqués dans des mécanismes importants pour les tumeurs et les métastases tels que la traduction et l’interaction des cellules avec la matrice extracellulaire. Contrairement à RPC7α, RPC7β est seulement localisée sur des gènes Pol III. Ainsi, ces résultats suggèrent que RPC7α agit avec la Pol II directement au niveau de gènes codants, peut-être pour favoriser leur expression, ce qui expliquerait son rôle important dans la croissance tumorale et la génération de métastases dans le CSTNRNA polymerase (Pol) III transcribes small non coding RNAs that are essential for the cell. There are two Pol III isoforms containing either RPC7α or RPC7β subunit. RPC7β is ubiquitously expressed whereas RPC7α is only expressed in embryonic stem cells and some tumor cells. Particularly, RPC7α is overexpressed in triple negative breast cancer (TNBC) clinical samples and cell lines. RPC7α deletion in the TNBC cell line MDA-MB-231 reduces tumor growth and metastases formation in a xenograft mouse model. However, the molecular mechanisms by which Pol IIIα regulates tumorigenesis and metastasis are still unknown. In this thesis, I show that the suppression of RPC7α in MDA-MB-231 cells alters the expression of several messenger RNAs, some of which are involved in the regulation of cancer and gene expression. Analysis of RPC7α localization indicates that, in addition to occupying Pol III genes, RPC7α also colocalizes with Pol II on coding genes. These genes are among the most highly expressed in MDA-MB-231 cells and are involved in important mechanisms for tumors and metastasis such as translation and cell interaction with the extracellular matrix. Unlike RPC7α, RPC7β is only localized on Pol III genes. Thus, these results suggest that RPC7α acts directly with Pol II on coding genes, possibly to promote their expression, which would explain its important role in tumor growth and metastasis generation in TNBC
2
Morais, Rui Pedro da Silva. "Poling em fibras ópticas". Master's thesis, Universidade do Porto. Reitoria, 2003. http://hdl.handle.net/10216/9747.
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Morais, Rui Pedro da Silva. "Poling em fibras ópticas". Dissertação, Universidade do Porto. Reitoria, 2003. http://hdl.handle.net/10216/9747.
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FRANCO, CAROLINE SOUSA. "GLASS ELECTROTHERMAL POLING AND CHARACTERIZATION TECHNIQUES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5435@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOERICSSON DO BRASIL
É possível criar uma não-linearidade de segunda ordem em amostras de sílica a partir do processo de polarização. Essas amostras vítreas com o X(2) induzido potencialmente podem ser utilizadas na fabricação de componentes como moduladores ópticos e dobradores de freqüência. O processo de polarização eletrotérmica utiliza alta tensão e alta temperatura e forma uma região de depleção de íons (camada de depleção) onde um campo elétrico intenso é gravado de forma permanente dentro da amostra. Neste trabalho, foram utilizadas diferentes técnicas de caracterização para medir a extensão dessa camada e os resultados foram comparados. As técnicas escolhidas foram: Ataque Químico Interferométrico (com ácido fluorídrico), Maker Fringe, Microscopia Óptica e de Força Atômica e Ataque Interferométrico com Medida de Segundo Harmônico em Tempo Real. Além disso, foram feitos alguns estudos paralelos visando à otimização e a reprodutibilidade do processo de polarização. Foram realizadas dessa forma análises sobre o material dos eletrodos utilizados e sobre a influência da condição inicial da superfície da amostra antes da polarização.
It is possible to create a second order non linearity in silica samples with the poling process. The glass samples with an induced X(2) have a potential application on the fabrication of optical devices such as modulators and frequency converters. In the electrothermal poling process, high voltage and high temperature are applied to the samples forming an ion depleted region (depletion layer), where an intense electric field is permanently recorded. In this work, several characterization techniques have been utilized to measure the width of the depletion layer and compared the obtained results. The chosen techniques were: Interferometric Etching, Maker Fringe, Optical and Atomic Force Microscopy and the Interferometric Etching with Real Time Second Harmonic Measurement. In addition to this, we performed other studies aiming the optimization and reproducibility of the poling process. In this way, we analyzed the material used for the electrodes and the influence of the initial condition of the sample surface before poling.
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ROJAS, GLADYS ADRIANA QUINTERO. "GLASS AND OPTICAL FIBER ELECTROTHERMAL POLING". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7862@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOComponentes ópticos para sistemas de telecomunicações estão em crescente demanda. Para aumentar a eficiência destes componentes, reduzir os custos e permitir a integração aos sistemas atuais, tem-se incentivado a pesquisa de novos materiais, como, por exemplo, a sílica fundida. Geralmente, a sílica fundida, por ser um meio isotrópico, não exibe efeitos não lineares de segunda ordem como o efeito eletro-óptico, que pode ser utilizado na fabricação de chaves e moduladores ópticos. No entanto, pode-se induzir na sílica uma não linearidade de segunda ordem (c(2)) da ordem de 1 pm/V através da técnica de polarização eletrotérmica. Observa-se a formação de uma camada depletada de íons e um campo elétrico muito intenso permanentemente gravado em sílica polarizada. A caracterização experimental desta camada de depleção, ou seja, espessura, perfil e magnitude do c(2) induzido, é importante para a compreensão do processo físico que ocorre durante a polarização. Podem ser encontrados na literatura resultados muito divergentes obtidos com diferentes técnicas de caracterização. Não se sabe se esta divergência é devida aos diferentes métodos usados, ou a diferentes condições de polarização e tipos de amostras. Nesta tese, fez-se uma comparação entre quatro técnicas de caracterização da espessura da camada de depleção em sílica polarizada: ataque químico interferométrico com ácido fluorídrico, Maker Fringe, microscopia óptica e de força atômica, e ataque interferométrico com medida de segundo harmônico em tempo real. A estabilidade da não linearidade induzida é importante para garantir a estabilidade de chaves e moduladores ópticos construídos com sílica polarizada, portanto, fez-se também um estudo de apagamento por temperatura da não linearidade induzida em amostras de sílica polarizada. Foi também estudado nesta tese a influência da superfície da amostra antes da polarização, fator importante para a otimização da reprodutibilidade do processo. Para investigar a potencialidade do desenvolvimento de um Atenuador Óptico Variável (VOA) a fibra óptica, também foi feito um estudo de polarização eletrotérmica em fibras ópticas. Estudos complementares foram realizados envolvendo a influência do campo elétrico na taxa de ataque de ácido fluorídrico em fibras ópticas. Fez-se também um estudo sobre redes de Bragg gravadas em fibras especiais. Parte desta tese foi financiada pelo CNPq (bolsa doutorado), pelo Convênio Ericsson/PUC-Rio - Termo Aditivo 04 e 14, ref: PUC.04, Polarização de fibras ópticas, e pelo Projeto GIGA - Finep - Funttel - CPqD, Subprojeto Atenuador Óptico Variável a Fibra Óptica.
Over the past few years, there has been a growing demand for optical components for telecommunication systems. In order to increase the efficiency of these components, reduce costs and allow integration to current systems, efforts have been made in researching new materials, for example, silica. Due to its isotropic nature, silica, ordinarily, does not present second order effects, for example, the electro-optic effect, which can be used for optical switching and modulation. However, eletrothermal poling can be used to induce in silica a second order nonlinearity (c(2)) of the order of 1 pm/V. It can be observed that poled silica has an ion-depleted layer and a permanently recorded electric field. The experimental characterization of this depletion layer, i.e. width, profile and magnitude of the induced c(2), is important for the comprehension of the physical process occurring during polarization. Different results obtained with different characterization techniques can be found in literature. It is not known whether diverging results in literature are due to different methods of examination or due to different poling conditions and sample type. This thesis compares the findings of four experimental techniques used to monitor the width of the depletion region in fused silica samples poled under similar conditions - hydrofluoric acid (HF) etching, Maker Fringe, optical and atomic force microscope, and hydrofluoric acid (HF) etching with real time monitoring of the SH signal. The stability of the induced nonlinearity is important to guarantee the stability of optical switches and modulators built with poled silica; therefore, thermal annealing of the induced nonlinearity in poled silica is also investigated in this thesis. The influence of the sample surface before poling, an important factor in reproducibility, is also investigated in this thesis. In order to investigate the possibility of developing an optical fiber Variable Optical Attenuator (VOA), optical fiber electrothermal poling was also investigated. Additionally, studies of the influence of the electric field strength on HF etching rate were made, as well as recording of Bragg gratings on special fibers. This thesis has been partially funded by CNPq (Doctorate scholarship), by Ericsson/PUC-Rio Accord - Additive term 04 e 14, ref: PUC.04, Poling of Optical Fiber, and by GIGA - Finep - Funttel - CPqD Project, Variable Optical Attenuator Subproject.
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Kianirad, Hoda. "Contact poling of RKTP with silicon needles". Thesis, KTH, Fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-120593.
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Sagen, Gard Olve. "Effect of resistance on performance in double poling". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for nevromedisin, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25605.
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The purpose of this study was to investigate what effect resistance would have on performance in double poling, with focus on power output, physiological responses and myoelectric activation. 6 elite male cross country skiers were exposed to simulated double poling in a Concept II Ski Ergometer at two different resistances, respectively low and high. The major findings were that power output significantly increased with the higher resistance, as well as work per cycle. These findings are previously shown in earlier research. Cycle rate remained unchanged, while stroke time increased. Earlier studies have confirmed that stroke time increase at added resistance or incline, to utilize a longer period of the cycle time to produce the required force to overcome the resistance or incline. Gross efficiency did not differ between the resistances, and no significant changes in electromyography activity were present. The increase in power output and work per cycle was therefore not attributed to an increased muscle activity. The main findings in this study are therefore inconclusive, and the increase in power output and work per cycle could be caused by other factors, such as muscle coordination and timing or changes in technical execution.
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Brennand, André Luiz Ribeiro. "Thermal poling of multioxide silicate glasses and ion-exchanged waveguides". Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/15487/.
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This Thesis reports a theoretical and experimental study of thermal poling of glasses in which a second order optical nonlinearity is introduced into the glass by applying a potential across the glass at elevated temperature. Thermal poling is the most reported and reproducible procedure for the introduction of the nonlinear susceptibility of 2nd order, c(2), in glasses. The attainment of c(2) of the order of 1pm/V has been reported in a wide range of silica based glasses including glasses suitable for ion exchange, UV-writing and rare earth doping. Effective c(2) of 0.1 pm/V has been demonstrated in poled channel waveguides in silica indicating a poor overlap between c(2) and the waveguide modes. These reported values of c(2) must be increased at least one order of magnitude for glasses and two orders of magnitude for waveguides for practical use. Therefore a good understanding of the poling mechanism which was unclear at the beginning of this work was required for poling optimisation. In this Thesis a poling model based on electrostatics and ion transport theory is developed yielding a method for the evaluation of glasses for poling. A new technique for simultaneous poling and waveguide fabrication by differential ionic drift in glasses that contains more than one mobile ion is demonstrated and poling of K+ ion-exchanged waveguides is achieved. c(2) of the order of 1 pm/V was verified in poled soda lime glass and in found in poled potassium ion-exchanged soda lime glass. A poling time for multioxide glasses some 5 times shorter and minimum temperature 50oC lower than reported in the literature was achieved with constant-current thermal poling in vacuum. A procedure to evaluate the average value, thickness and the location of the c(2) region is established. This study provides an improved understanding of the poling mechanism and may contribute to the achievement of higher c(2) in poled glasses and poled waveguides in glasses.
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Zukauskas, Andrius. "QPM Devices in KTA and RKTP". Doctoral thesis, KTH, Laserfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-139475.
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Even though KTiOPO4 (KTP) is considered to be one of the best nonlinear materials for quasi phase matched (QPM) frequency conversion in the visible and the near-infrared spectral regions, its use is often limited by poor material homogeneity, high ionic conductivity, a considerable linear absorption and photochromatic damage. On the other hand, the improved material homogeneity and the lower ionic conductivity of bulk Rb-doped KTP (RKTP) make this material an ideal alternative for fabrication of fine-pitch QPM gratings, while the arsenate isomorph KTiOAsO4 (KTA) promises a better performance in the green spectral region and adds the advantage of a wider transparency window in the infrared. Unfortunately, the available studies on these materials are limited and unable to answer the question whether RKTP and KTA are feasible alternatives to KTP in terms of periodic poling and optical performance. The optical performance of the QPM devices depends on the periodic poling quality, therefore, a detailed comprehension of domain-grating formation in the KTP isomorphs is highly desired. The goals of this thesis were to gain a better understanding of the periodic poling process in the KTP isomorphs, in order to study the specifics of ferroelectric domain engineering in KTA and RKTP, and to evaluate the optical performance of these isomorphs. Fine-pitch periodically poled structures were engineered both in KTA and RKTP crystals. It was demonstrated that QPM gratings with excellent quality and with periods as short as 8.49 μm can be fabricated in KTA crystals. Comparative transmission studies have shown that periodically poled KTA (PPKTA) crystals can be superior to KTP for QPM second harmonic generation in the visible spectral region due to lower linear absorption. It was also demonstrated that RKTP is a superior alternative to KTP for high-quality QPM grating fabrication. A consistent room-temperature periodic poling of 5 mm thick RKTP crystals with a period of 38.86 μm has been achieved. The obtained large aperture periodically poled RKTP (PPRKTP) crystals showed an outstanding QPM grating uniformity and excellent optical performance in optical parametric oscillator (OPO) applications. Moreover, it was shown that RKTP is less susceptible to blue-induced infrared absorption than KTP. Finally, a novel and a relatively simple method for self-assembling quasi-periodic sub-μm scale ferroelectric domain structure in RKTP crystals has been presented. It was shown that, after treatment in aqueous KOH/KNO3 solution, periodic poling of RKTP with planar electrodes resulted in one-dimensional ferroelectric domain structure with an average periodicity of 650±200 nm, extending over the whole 1 mm thick crystal. Such self-assembled structures in RKTP were used to demonstrate 5th order non-collinear QPM backward second harmonic generation.QC 20140114
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Laplante, Philippe. "Poling thermique sur lame de silice : sous haute température et tension". Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24638/24638.pdf.
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Nagy, Jonathan Tyler. "Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587673156665861.
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QUATELA, ALESSIA. "Electrical and all-optical poling of nonlinear optical materials: relaxation dynamics". Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2005. http://hdl.handle.net/2108/202923.
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Il presente lavoro è motivato dalla necessità di trovare nuovi materiali polimerici o ibridi organiciinorganici per la realizzazione di modulatori elettroottici. Per essere utilizzati in un dispositivo reale, i materiali dotati di proprietà ottiche nonlineari devono possedere elevata attività nonlineare e stabilità temporale. Affinché un materiale esibisca proprietà ottiche nonlineari del secondo ordine, esso deve essere sottoposto ad una procedura post-deposizione che definisca una direzione preferenziale in un sistema in partenza centrosimmetrico. A questo scopo sono state utilizzate due diverse tecniche di orientamento: corona e all-optical poling. La prima tecnica, studiata nel laboratorio NeMO, utilizza un campo elettrico statico per orientare le molecole, la cui mobilità viene aumentata innalzandone la temperatura. La seconda, utilizza la sovrapposizione di due sorgenti coerenti alle frequenze ω e 2ω per indurre una polarizzazione su campioni mantenuti a temperatura ambiente. In particolare, questa parte di lavoro è stata sviluppata nel Laboratoire des Propriétés Optiques des Matériaux et Applications (POMA) presso l’Università di Angers, grazie ad una borsa di studio finanziata dal COST P8. Grazie a queste tecniche di poling, i dipoli delle molecole possono essere orientati in una direzione parallela o perpendicolare alla superficie del film. Tale orientazione è stata caratterizzata tramite misure di assorbimento di luce polarizzata (PAS) e di generazione di seconda armonica (SHG). Utilizzando la temperatura come agente degradante, sono stati effettuati test di invecchiamento accelerato su film sottili di materiale polimerico e ibrido organico-inorganico sintetizzato con la tecnica sol-gel. Le curve di decadimento rivelano un andamento doppio esponenziale. Riportando il tempo di rilassamento lento in funzione della temperatura di invecchiamento, è stato possibile estrapolare, tramite un relazione tipo-Arrehnius, il tempo di rilassamento a temperatura ambiente. Due materiali sono risultati promettenti per le applicazioni desiderate: un sistema polimerico basato su una poliimide e un sistema ibrido. La realizzazione di un dispositivo elettroottico verrà realizzata in collaborazione con un’industria italiana. Questo lavoro di tesi rientra nell’ambito di un progetto europeo (ODEON) ed è stato sviluppato principalmente nel laboratorio NeMO presso l’Università di Roma “Tor Vergata”.The present thesis is motivated by the attempt to find polymeric or hybrid organic-inorganic materials for electrooptic modulators. For practical uses, nonlinear optical (NLO) materials must possess both large nonlinearity and temporal stability. Second order NLO properties appear after some additional post-deposition procedures. Indeed, after deposition, these composed materials are centrosymmetric and, as such, not endowed of second order properties. Poling, i.e. the orientation of the molecular dipoles, is necessary in order to break this centrosymmetry. Two different poling methods are investigated and discussed: corona and all-optical poling. The first technique, developed in the NeMO laboratory, involves a dc electric field, used to orient the dipoles of the material at a temperature where the molecule dipoles can rotate. The second one uses two coherent sources possessing different frequencies (ω and 2ω) to induce a reversible static polarization inside the medium at room temperature. This last work was performed in the Laboratoire des Propriétés Optiques des Matériaux et Applications (POMA) at the University of Angers thanks to the COST P8 grant. By poling, the dipoles can be oriented parallel or perpendicular to the film plane. Linear (Polarized Absorption Spectroscopy-PAS) and nonlinear (Second Harmonic Generation-SHG) characterizations are performed on the studied systems in order to reveal the orientation. Accelerated aging tests are performed using temperature as degrading agent and polar order decay monitored by SHG. All the decay curves are well fitted by a double exponential function. An extrapolation of the slower relaxation time using the Arrhenius model, permits to obtain the stability of nonlinear properties at room temperature. Macroscopic second order nonlinearities, orientation mechanisms (raise and decay of the poled order responsible for the nonlinearity) and chemical nature of different systems are discussed. At least two promising materials are found, a polyimide-based and a hybrid sol-gel-based system, and the fabrication of a prototype of electrooptic modulator is envisaged in collaboration with the research centers of some Italian private companies. This work is pursued mainly under the ODEON European project and performed in the NeMO laboratory at the University of Roma “Tor Vergata.
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Moura, André de Lima. "Processo alternativo de polarização termo-elétrica de indução e caracterização de não-linearidade de segunda ordem em vidros soda-lime". Universidade Federal de Alagoas, 2009. http://repositorio.ufal.br/handle/riufal/1000.
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Amorphous materials present macroscopic inversion symmetry. As a consequence, their even
order nonlinearities are null. The technological interest in vitreous medium with second order
nonlinearity ( χ(2) ) to make photonic devices has stimulated the development of techniques to
induce this property. Among them, the thermal-electric field poling is one of the most
investigated due its experimental simplicity and results reproducibility.
In this work the investigations were directed to the thermal-electric field poling dynamics in
soda-lime glasses in view of identify the mainly contributions to the induced nonlinearity
stability. Initially were identified the mainly contributions to the induced electrical current. It was
observed during the polarizations electroluminescence emission which was shown to be due to
ionic displacement and air ionization outside the sample. By using a simplified ionic conduction
model was determined two activation energies: ~0,60 and ~3,8eV. The first one, determined from
the induced electrical current, was attributed to the sodium conduction; while the second ones,
determined by the electroluminescence, attributed to the calcium displacement. Besides the small
contribution to the electrical current, the calcium ions, due their small diffusion coefficient, were
identified as responsible to the possibility of induce stable second order nonlinearity in soda-lime
glasses. Based on these evidences it was used an alternative procedure in which the electrical
current flux is controlled. This procedure enabled induce stable χ(2) . This effect was
demonstrated to exist 12 months after the polarization procedure, even with a ~50% decrease.
The second harmonic generation efficiency was increased in until three times by pumping
continuously the polarized samples with infrared radiation from an Nd-YAG laser operating at
QSML regime. The threshold applied voltage to observe χ(2) was determined through a
modulated applied voltage procedure to be due to the mobility difference between sodium and
calcium.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Materiais amorfos apresentam simetria de inversão macroscópica e, como conseqüência, as nãolinearidades ópticas de ordem par são nulas. A necessidade tecnológica de que meios vítreos apresentem não-linearidade de segunda ordem ( χ(2) ), visando principalmente o desenvolvimento de dispositivos fotônicos, fortalece a busca por técnicas para a sua indução. Dentre estas, o processo termo-elétrico de polarização tem sido muito investigado devido, principalmente a sua simplicidade experimental e a reprodutibilidade dos resultados. Neste trabalho as investigações são dedicadas à dinâmica do processo termo-elétrico em vidros soda-lime visando identificar as principais contribuições para a estabilidade da não-linearidade induzida. Inicialmente foram verificadas as principais contribuições à corrente elétrica induzida. Durante as polarizações observou-se emissão de eletroluminescência. Mostrou-se que esta é devido ao deslocamento dos íons de cálcio e possíveis ionizações do ar fora da amostra. Usando um modelo simplificado de condução iônica determinou-se duas energias de ativação: ~0,60 e ~3,8eV. A primeira, determinada a partir da corrente elétrica induzida, foi atribuída à condução dos íons de sódio; enquanto a segunda, determinada pela eletroluminescência, aos íons de cálcio. Apesar de pequena contribuição na corrente elétrica induzida, os íons de cálcio, devido ao baixo coeficiente de difusão, foram identificados como os responsáveis pela possibilidade de indução de χ(2) estável em vidros soda-lime. Baseado nessas evidências foi utilizado um procedimento alternativo de polarização controlando do fluxo de corrente induzida que permitiu a indução de χ(2) estável. Este efeito pôde ser comprovado existir 12 meses após o processo de polarização, mesmo com redução de ~50% do valor inicial. Observou-se que a eficiência na geração de segundo harmônico pôde ser aumentada em até 3 vezes quando as amostras polarizadas foram bombeadas continuamente com laser Nd-YAG operando no regime QSML. Através de procedimento com tensão elétrica aplicada modulada foi identificada a origem da tensão elétrica de limiar como sendo devido à diferença de mobilidade entre os íons de sódio e cálcio.
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Healy, David. "Solid solution studies of the molecular nonlinear optical properties of organic chromophores". Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5435/.
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The work presented in this thesis describes an investigation into the properties and behaviour of nonlinear optical guest molecules doped into polymeric matrices. The interactions of the guest molecule 2-(N, N dimethylamino)-5-nitroacetanilide (DAN) with a polycarbonate and polymethyl methacrylate (PMMA) host are compared. A detailed characterisation of the two systems is described employing infra red spectroscopy and analysis of the chromophore alignment during electric field poling. The study reveals that hydrogen bond formation between the guest and the polar polycarbonate backbone accounts for the unusually good alignment stability previously reported in the polycarbonate system. The molecular hyperpolarisibility of DAN in PMMA is also measured and the apparent enhancement compared with solution measurements is accounted for by the more polar nature of the polymer environment. A new technique allowing the measurement of the dipole moment of polar molecules doped into thin polymer films is also presented. The technique is demonstrated on a series of zwitterionic chromophores whose measured dipole moments range from 30 to 40 D. Electrochroism measurements are performed to account for aggregation of the monomer species which then permits the first hyperpolarisibility of the molecules to be calculated. The values of dipole moment and hyperpolarisibility are found to be very sensitive to the choice of dielectric cavity shape used when deriving the local field correction factors. The measured values are therefore compared with theoretical calculations and a preferred cavity shape is proposed.
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TANAKA, Keisuke, Yoshiaki AKINIWA, Yoshihisa SAKAIDA e Hirohisa KIMACHI. "Lattice Strain and Domain Switching Induced in Tetragonal PZT by Poling and Mechanical Loading". The Japan Society of Mechanical Engineers, 2000. http://hdl.handle.net/2237/9183.
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Marois, Chantal. "Réalisation d'une procédure de traitement des fibres optiques par poling thermique et ultra-violet". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0018/MQ48865.pdf.
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Boyland, Alexander John. "Microstructuring and domain-engineering of lithium niobate using combinations of light, etching and poling". Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/15479/.
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The work presented in this thesis reports methods for microstructuring of lithium niobate. The process of light induced frustrating etching, where light from a laser is used to inhibit the etching of iron doped lithium niobate, is the subject of a detailed investigation so a better understanding of the process can be developed. The process was found to be dependent upon illumination and etch times, iron dopant levels, and irradiance levels. Analysis of the structures formed revealed that they were resistant to the etchant used and were positively charged. Two dimensional Fourier transform analysis of images obtained were used to confirm that the structures preferentially propagated along 3 directions each 120o apart. A novel electro-optically controlled domain-engineered total internal reflection switch and beam deflector is also reported. Device construction uses electric field poling of lithium niobate to create two parallel but oppositely oriented domains. When an electric field is applied across the interface between these domains a change in the refractive index of equal magnitude but of opposite sign is induced. If light incident on this interface sees a sufficient difference in refractive index it can be total internally reflected. The total internal reflection switch shows high contrast ratio switching of greater than 20dB and is less wavelength dependent than other electro-optic switches, such as the Pockels cell. The beam deflector can produce large angular deflections, which are increased by faceting of the output face. Deflections of greater than 18o have been demonstrated using this technique. Cascading of devices and possible device implementations are also suggested.
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Kårström, Andreas. "The effect of carbohydrate mouthrinse on simulated XC-sprint performance". Thesis, Mittuniversitetet, Avdelningen för hälsovetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-22998.
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The purpose with this study was to investigate the effect of a carbohydrate (CHO) mouth rinse protocol on simulated cross country (XC) sprint. The primaryaim was to investigate ifa 10 secCHO solutionmouth rinsingprotocolimprovedthe finish timein a simulated cross country (XC) sprint(800 meters for female and 1000 meters for male) compared with control (CON).The second aim was to examif post-finish blood lactateconcentrationwouldbe lowercompared with CONwith mouth rinsing. Seven participants(four males and three females)completed four simulated sprints, two CON and two experimentalrinse protocols, CHO solution and placebo (PLA).Time to completion was not different with CHO compared with CON or PLA (203.0 ±16.5 sec, 202.3 ± 15.7 sec, 203.3 ± 14.6respectively.p >.05).Mean power output was CON 264 ± 73, PLA 258 ± 65, CHO 261± 70.Blood lactateat 15 minweresimilar between CHO, CON and and PLA(9.9 ± 3.9 mmol 7.6 ± 4.0 mmol, 10.1 ± 3.7 mmol respectively.p >.05).We concludethat mouth rinsing a CHO solutionfor 10 sechave no effect on high intensity exercise with duration lasting between 3 and 4 minutes.
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Azevedo, Samuel Oliveira de. "Sistema de agentes polig?nicos para estegan?lise de imagens digitais". Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17965.
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Previous issue date: 2007-08-06Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
In this work, we propose a multi agent system for digital image steganalysis, based on the poliginic bees model. Such approach aims to solve the problem of automatic steganalysis for digital media, with a case study on digital images. The system architecture was designed not only to detect if a file is suspicious of covering a hidden message, as well to extract the hidden message or information regarding it. Several experiments were performed whose results confirm a substantial enhancement (from 67% to 82% success rate) by using the multi-agent approach, fact not observed in traditional systems. An ongoing application using the technique is the detection of anomalies in digital data produced by sensors that capture brain emissions in little animals. The detection of such anomalies can be used to prove theories and evidences of imagery completion during sleep provided by the brain in visual cortex areas
Neste trabalho, propomos um sistema multi-agentes para estegan?lise em imagens digitais, baseado na met?fora das abelhas polig?nicas. Tal abordagem visa resolver o problema da estegan?lise autom?tica de m?dias digitais, com estudo de caso para imagens digitais. A arquitetura do sistema foi projetada n?o s? para detectar se um arquivo ? ou n?o suspeito de possuir uma mensagem oculta em si, como tamb?m para extrair essa mensagem ou informa??es acerca dela. Foram realizados v?rios experimentos cujos resultados confirmam uma melhoria substancial (de 67% para 82% de acertos) com o uso da abordagem multi-agente, fato n?o observado em outros sistemas tradicionais. Uma aplica??o atualmente em andamento com o uso da t?cnica ? a detec??o de anomalias em dados digitais produzidos por sensores que captam emiss?es cerebrais em pequenos animais. A detec??o de tais anomalias pode ser usada para comprovar teorias e evidencias de complementa??o do imageamento durante o sono, provida pelo c?rebro nas ?reas visuais do c?rtex cerebral
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Kudlinski, Alexandre. "Étude des non-linéarités d'ordre deux créées dans les verres de silice par poling thermique". Lille 1, 2005. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2005/50376-2005-Kudlinski.pdf.
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Les matériaux vitreux possèdent une centro-symétrie macroscopique qui interdit la présence de non-linéarités optiques du second ordre. Un traitement de polarisation thermique, appelé poling thermique, permet néanmoins de créer une susceptibilité non-linéaire d'ordre deux dans les verres, en soumettant le matériau chauffé à une tension élevée. Ce résultat est expliqué par la présence d'un champ électrique statique figé dans la matrice vitreuse sur une épaisseur d'une dizaine de micromètres. Nous proposons une méthode de caractérisation originale des non-linéarités d'ordre deux, consistant à enregistrer la puissance de l'onde de second harmonique au cours d'une attaque chimique de l'échantillon polé, La mesure interférométrique en temps réel de l'épaisseur enlevée nous permet de reconstruire la distribution spatiale de la susceptibilité du second ordre avec une résolution submicrométrique, à l'aide d'un algorithme itératif. Nous étudions ensuite la dynamique de formation de la non-linéarité d'ordre deux: nous montrons expérimentalement que la forme de son profil évolue au cours du traitement de poling. Ce comportement est simulé à l'aide d'un modèle de migration cationique à deux porteurs de charge. Enfin, nous montrons que la distribution spatiale de la non-linéarité d'ordre deux dépend également de phénomènes annexes (modification de la susceptibilité non-linéaire d'ordre trois, chute de potentiel nulle entre les deux faces de l'échantillon), qui ne peuvent pas être négligés pour la réalisation de composants actifs fibrés basés sur l'exploitation d'effets non-linéaires du second ordre.
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Kudlinski, Alexandre Martinelli Gilbert Zeghlache Hassina. "Étude des non-linéarités d'ordre deux créées dans les verres de silice par poling thermique". Villeneuve d'Ascq : Université des sciences et technologies de Lille, 2007. https://iris.univ-lille1.fr/dspace/handle/1908/595.
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Reproduction de : Thèse de doctorat : Lasers, Molécules et Rayonnement atmosphérique : Lille 1 : 2005.N° d'ordre (Lille 1) : 3662. Résumé en français et en anglais. Titre provenant de la page de titre du document numérisé. Bibliogr. p. 219-229. Liste des publications.
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Karam, Lara. "Structuration multi-échelle et multifonctionnelle de nouveaux matériaux vitreux pour la photonique intégrée". Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0178.
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L’objectif de ces travaux est de contrôler, tant à l’échelle macroscopique que microscopique, les propriétés électriques, chimiques et optiques (linéaires et non linéaires) de matériaux vitreux originaux par un procédé de micro-polarisation thermique. La démarche adoptée consiste à explorer les liens entre la structure du matériau, le procédé et les propriétés avant et après traitement. Trois types de matériaux ont été étudiés : des verres massifs borophosphates de sodium et niobium, des couches minces amorphes sodo-niobates et des verres massifs chalcogénures (GeSbSNa). Nous avons mesuré dans les couches minces sodo-niobates amorphes, une très forte réponse optique du second ordre (30 pm/V) micro-localisée ; dans les verres chalcogénures, une structuration à l’échelle micrométrique du potentiel électrique de surface a été obtenue. Nous démontrons ainsi le potentiel de la combinaison de ces matériaux et ce procédé, pour de futures intégrations dans des systèmes photoniques planaires multifonctionnelsThis work aims for a macro- as well as microscopic control of electrical, chemical and (linear and nonlinear) optical properties via a thermo-electrical process applied to original amorphous materials. The selected approach consists in exploring the relationships between the material’s structure, the process and the, prior to- and post-process properties. Three types of glasses were under study: bulk sodium and niobium borophosphate glasses, sodo-niobate amorphous thin films and bulk GeSbSNa chalcogenide glasses. We have measured a strong micro-localized second order response (30 pm/V) induced in the amorphous thin films; on the chalcogenide glasses, the structuring at the micrometric scale of the electrical surface potential was shown. With these attributes, we demonstrate the potential of these material/process associations for future integration in multifunctional photonic circuits
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Baker, Jacqueline. "The rise of Polri : democratisation and the political economy of security in Indonesia". Thesis, London School of Economics and Political Science (University of London), 2012. http://etheses.lse.ac.uk/3132/.
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In Indonesia, successful democratisation from military authoritarian rule has pushed the military ‘back to the barracks’ and restored the rule of law. This process of moving from authoritarian-military to civil-juridical authority has taken place in multiple ways across the political system, however most notably in the rise of the police as an institutional actor, the restoration of their authority over domestic and national security and law enforcement. Scholarship shows how criminality and the criminal contingent have been crucial in every way to state formation in Indonesia. Throughout history, the security institutions have mediated those forms of criminality and the state’s overarching relationship with the illicit. One of the ways the relationship between the state and criminal practices has manifested itself has been in the mechanisms of illicit extraction and accumulation broadly known as “corruption”. Despite the regularizing effects of democratisation, the security sector continues to be resourced primarily by a vast illicit economy, called the off-budget economy. I show how Polri’s new authoritative role in security and law enforcement has opened up the spoils of this economy to the police in two important criminal economies; the gift economy of indigenous Chinese traders and the illegal gambling economy in Jakarta. This thesis demonstrates how the transformation from military-coercive to civil juridical modalities of power has not improved the quality of Indonesia’s democracy or rule of law. Rather, democratisation has caused a restructuring in the political economy of security and facilitated the rise of Polri as a perverse political actor within the Indonesian state and society. The intimacy of the Indonesian state with illicit practices has been reconfigured anew.
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AlSaeed, Abdulelah (Abdulelah Ibrahim). "Elimination of PZT thin film breakage caused by electric current arcing and intrinsic differential strains during poling". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78161.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 66).
Historically, substrate breakage during the poling process has been responsible for a 2% yield loss for a contract manufacturer specializing in volume production of lead zirconate titatate (PZT) thin film devices. In this research, two major causes of poling breakage were identified. First, stresses along substrate edges make PZT substrates more susceptible to breakage if any sort of mechanical force is present. It was determined that these stresses were caused by differential strains due to incomplete metal layer coverage. Second, the electrical arcing that is frequently taking place during poling sends a mechanical shock wave through the substrate. Electrical arcing is caused by metal overspray during the sputtering process. Poling breakage was experimentally reduced by 70% by redesigning the shadow mask used during sputtering to eliminate any metal overspray.
by Abdulelah Alsaeed.
M.Eng.
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Blum, Raphaël. "Etude de la distribution de charges électroniques au sein de verres isolants et son application au poling". Paris 11, 2006. http://www.theses.fr/2006PA112275.
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Les materiaux vitreux possedent une centrosymetrie macroscopique qui interdit les non-linearites optiques du second ordre. Untraitement de poling thermique, consistant a appliquer sous chauffage, un champ electrique, permet neanmoins de creer une susceptibilite non-lineaire d’ordre deux d’environ 1 pm/v. Ceci en raison du champ electrique interne genere au sein du materiau par la migration d’especes cationiques. Cette these porte sur l’etude de procedes alternatifs de poling, pour lesquels le champ electrique interne resulte de la migration d’especes electroniques (electrons et/ou trous). Dans un premier temps, nous abordons l’irradiation par faisceau d’electrons et la mesure du rendement d’emission secondaire. Nous discutons de l’influence de divers parametres experimentaux sur la valeur et l’evolution du rendement d’emission electronique secondaire et montrons que de telles mesures permettent d’evaluer le caractere isolant (ou “piegeur”) des verres etudies et ainsi de tester leur aptitude a conserver une charge d’espace induite par polingla suite de notre travail traite du poling par faisceau d’electrons et du poling par rayons x. Nous y detaillons nos travaux visant a l’optimisation des differents parametres d’irradiation et leur effet sur les performances optiques atteintes. Enfin, nous jetons les bases d’une modelisation de la charge d’espace induite lors d’une irradiation par faisceau d’electrons ou par rayons x. Ce modele, une fois complet, nous permettra une meilleure interpretation des courbes de rendements d’emissions electroniques secondaires ainsi qu’une optimisation des conditions de poling par les deux procedes etudiesVitreous materials have a macroscopic centrosymetry that prohibits second-order optical non-linearities. A thermal poling treatment i. E. Applying an electric field under heating, makes it possible nevertheless to create a second-order non-linear susceptibility of about 1 pm/v. This was explain by the creation of an internal electric field due to cationic species migration. This thesis deals with alternative poling processes, for which the internal electric field results from the migration of electronic species (electrons and/or holes). We, firstly, describe the effect of an e-beam irradiation an a sample and the measurement of the secondary electron emission yield (seey). We discuss the influence of various experimental parameters on the value and the evolution of seey and show that such a measurements is a usefull tool to evaluate the insulating properties of various glasses and thus test their ability to store a poling induced space charge. Then, we explain the basis of e-beam and x-ray poling and detail our work on the optimization of the various irradiation parameters and their effect on the non-linear optical properties. Finally, we report our attempt to modelize the space charge induced during an e-beam or x-ray irradiation model, once completed, such a model, could give us a better understanding of the seey curves as well as the optimized poling conditions
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Anagnostou, Maria-Eleni. "The role of POLG mutations in human disease". Thesis, University of Newcastle upon Tyne, 2018. http://hdl.handle.net/10443/4082.
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Mitochondrial diseases due to mutations in the nuclear Polymerase gamma (POLG) gene, have emerged as a common group of disorders, collectively referred to as POLG-related disorders. POLG is responsible for mitochondrial DNA (mtDNA) replication and repair. Defects in POLG result in secondary mtDNA defects including mtDNA depletion and deletions, which result in respiratory chain deficiency in affected tissues. POLG-related disorders are characterised by phenotypic diversity with common neurological deficits such as epilepsy, which constitutes its predominant manifestation. Alpers' syndrome is a severe form of POLG-related disorders and it is a rare, early-onset, progressive encephalohepatopathy characterised by: intractable seizures, developmental delay, ataxia, visual loss and liver dysfunction. It is particularly devastating as effective treatments do not currently exist, and little is known about its molecular pathophysiology downstream from POLG mutations. The aim of this work was to gain further insight into the pathogenesis of Alpers, through the characterisation of mitochondrial dysfunction in POLG-mutant fibroblasts, and neuropathological investigation of post-mortem brain tissue from affected patients. Fibroblast characterisation using quantitative methodologies, revealed no evidence of mitochondrial dysfunction in primary POLG-mutant fibroblasts derived from patients with Alpers. Neuropathological assessment of three cortical regions revealed extensive respiratory chain deficiencies in interneurons and to a lesser extent pyramidal neurons in patients with Alpers, which was associated with severe pyramidal neuron loss. A variable degree of astrogliosis, was also observed. Additionally, mtDNA depletion was found in tissue from adult patients with POLG-mutations as well as occasional mtDNA deletions. This study provides evidence that POLG mutations exert a tissue-specific effect in Alpers. Mitochondrial respiratory chain deficiencies in interneurons and pyramidal neurons, combined with extensive pyramidal neuron loss may result in altered neuronal dynamics and contribute to the underlying neuropathology and clinical manifestations of Alpers.
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Wegert, Zach. "Analysis and optimisation of periodic piezoelectric materials". Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/232770/1/Zachary_Wegert_Thesis.pdf.
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This project developed computational tools to analyse and design novel piezoelectric materials that have the potential to be utilised in next-generation electromechanical devices. The thesis demonstrates how such architectured materials can be used in the design of multi-functional robotic ‘pain’ sensors.
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Califano, Valeria. "Étude structurale de verres d'oxydes pour l'optique non linéaire : croissance de nanostructures et effet d'un champ électrique ('poling')". Lyon 1, 2005. http://www.theses.fr/2005LYO10103.
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L'induction de l'anisotropie dans les verres permet le développement de matériaux optiquement non linéaires pour la génération de seconde harmonique. L'intérêt principal réside dans les avantages que les matériaux vitreux présentent par rapport aux cristaux (mis en forme aisée, faible coût, large gamme de compositions et formes). Différentes techniques ont été utilisées pour induire l'anisotropie dans les verres: le ‘poling DC' (polarisation sous champ électrique continu) et la croissance de nanostructures respectivement sur des verres LBG (La2O3-B2O3-GeO2) et KNS (K2O-Nb2O5-SiO2). Utilisant la spectroscopie Raman et la diffusion des neutrons et des rayons X aux petits angles, nous avons mis en évidence la biréfringence et les effets d'anisotropie induits par le ‘poling' des verres LBG ainsi que des modifications dans les verres nanostructurés. Ces études offrent des perspectives nouvelles pour l'élaboration de matériaux vitreux présentant des propriétés optiques non linéaires
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Faraj, Rim. "Elaboration de verres sodocalciques dopés avec des nanoparticules métalliques et semi-conductrices". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSES041.
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L’objectif de cette thèse est de doper des verres sodocalciques avec des nanoparticules d’argent, d’or et de cobalt. La procédure suivie dans ce travail repose sur l’association des techniques d’échange ionique thermique (classique ou assisté par champ électrique) et d’une insolation laser UV continue (244nm). La première partie de la thèse concerne l’effet de l’oxygène sur la croissance des nanoparticules d’argent. Nous avons démontré un effet réducteur de l’oxygène sur les ions argent et par suite un effet positif sur la croissance des nanoparticules. La deuxième partie de la thèse concerne le dopage des verres avec des nanoparticules d’or. Nous avons démontré que la formation de nanoparticules d'or dépend fortement de la température appliquée durant l’échange ionique. Après optimisation des paramètres expérimentaux, nous avons pu montrer l’efficacité de nos substrats pour la détection par effet SERS de molécules très peu concentrées. La dernière partie de ce travail porte sur les résultats obtenus avec le cobalt. Nous avons démontré la formation de nanoparticules de Co3O4 et de CoO à la surface des verres. L’étude Raman menée a permis de montrer la possibilité de contrôler la phase cristalline de l’oxyde de cobalt. Mes travaux s’achèvent sur l’étude du co-dopage des verres par des nanoparticules d’argent et de cobalt. La faisabilité de ce co-dopage a été démontrée et nous avons pu mettre en évidence l’oxydation préférentielle du cobalt vis-à-vis de l’argent, ouvrant de nouvelles voies autant sur l’optimisation des capteurs à effet SERS, que vers des applications magnéto-optiques potentiellesThe aim of this thesis is to dope soda-lime glasses with either silver, gold or cobalt nanoparticles. The experimental procedure is based on the successive combination of thermal ion exchange techniques (conventional or assisted by electric field) and continuous UV laser irradiation (244 nm).The first part of this work concerns the effect of oxygen on the growth of silver nanoparticles. We have demonstrated a reducing effect of oxygen on silver ions which favors the growth of silver nanoparticles during the laser exposure.The second part of this work is dedicated to the doping of the glass with gold nanoparticles. We have shown that the formation of gold nanoparticles strongly depends on the temperature applied during the ion exchange. After optimization of the experimental parameters, we have been able to show the efficiency of our substrates for the detection of very low concentrated molecules diluted in liquid solution, using the well-known SERS technique.The last part of this work deals with the results obtained with cobalt. We have demonstrated the formation of either Co3O4 or CoO nanoparticles located at the glass surface. Raman study has shown the possibility to favor etiher one of these two phases. The feasibility of co-doping the glass by silver and cobalt has also been demonstrated and we have highlighted the preferential oxidation of cobalt with respect to silver, opening new perspectives such as the optimization of SERS sensors or for potential magneto-optical applications
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Polig, Raphael [Verfasser], Walter [Akademischer Betreuer] Stechele e Marco [Akademischer Betreuer] Platzner. "Text Analytics on Reconfigurable Platforms / Raphael Polig. Betreuer: Walter Stechele. Gutachter: Marco Platzner ; Walter Stechele". München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/108029936X/34.
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Danielsen, Jørgen. "The Effect of Intensity on Joint-Specific Power and Mechanical Energy during Double Poling in Elite Cross-Country Skiers". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for nevromedisin, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25602.
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Purpose: The present study examined the absolute behavior and the relative contributions to poling power of 1) joint-specific powers and 2) total body power (Pbody, i.e. the rate of change in total body mechanical energy) at increasing intensities while ergometer double poling. Methods: Nine male elite skiers (body mass 81.7 ± 6.5 kg, height 1.86 ± 0.06 m) performed three 4-min submaximal trials at low (LOW), moderate (MOD), and high (HIGH) intensity, and one 3-min all-out peak test (MAX). All trials were performed standing on a force plate and the ergometer was equipped with a force cell in order measure all external forces acting on the body. Reflective markers were placed on anatomical landmarks. Kinetics and kinematics were synchronized and recorded. By applying inverse dynamics, joint-specific powers (elbow, shoulder, trunk, hip, knee and ankle) and Pbody was calculated for the poling and retrieval phase, and for the complete cycle. Results: As net cycle poling power increased (116 ±16 W. 166 ± 36 W, 214 ± 38 W, and 306 ± 38 W at LOW, MOD, HIGH, and MAX, respectively; all p < 0.05) the relative contribution of the lower extremities increased from 39 ± 14 % at LOW to 65 ± 11 % at MAX (p < 0.05). The relative contribution of the upper extremities was stable at ~28 ± 6 %. Pbody fluctuated over the cycle, being generated during the retrieval phase (~100% of lower extremities positive power) and partly transferred to poling power during the poling phase. More specifically, Pbody was the main contributor to poling power (66 ± 13 % at LOW and 54 ± 7 % at MAX). Overall, most power was produced by the body’s core, i.e. the hip, trunk, and shoulder joints. Conclusion: The lower extremities generate an increasing amount of Pbody during the retrieval phase, which was thereafter partly transferred to poling power during the poling phase. Enhancing the lower extremities’ work as a way of increasing Pbody during the retrieval phase seems crucial for optimal utilization of Pbody during poling phase. Key words: double poling, biomechanics, inverse dynamics, energy, cross-country skiing
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Escanhoela, Júnior Carlos Augusto. "Condutividade elétrica e polarização térmica de vidros soda-cal-sílica contendo diferentes cátions tetravalentes /". Rio Claro : [s.n.], 2011. http://hdl.handle.net/11449/91918.
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Orientador: Ervino Carlos ZiemathBanca: Dante Luis Chinaglia
Banca: Victor Ciro Solano Reynoso
Resumo: Neste trabalho realizamos a polarização térmica em vidros silicatos com composição (%mol) 22Na2O.8CaO.65SiO2 .5MO2 (M = Si, Ti, Ge, Zr, Sn e Ce). A polarização térmica consiste em aplicar um campo elétrico DC de elevada intensidade (~1 MV/m) em amostras a altas temperaturas. Durante a polarização térmica é gerado um campo elétrico permanente no interior da amostra, na região do anodo, que é responsável por propriedades ópticas nãolineares. Submetemos à polarização térmica amostras dos vidros, com ~1,5 mm de espessura e área de 20 x 20 mm2. Utilizamos eletrodos de Au, com diâmetro de 1 cm. As amostras foram aquecidas no interior de um forno até ~145 oC e aplicamos um campo elétrico de 1 MV/m durante 60 min. Durante a aplicação do campo elétrico, medimos simultaneamente a corrente através do circuito e as temperaturas no forno e na amostra. A corrente elétrica medida no circuito está relacionada com a migração de íons Na+ no interior das amostras do anodo para o catodo. A diminuição da corrente após um determinado tempo de polarização é devido à formação de uma camada com ausência de íons Na+ (camada de depleção) junto ao anodo. Os diferentes cátions tetravalentes, M4+, inseridos no vidro têm funções particulares na estrutura deste e afetam de formas distintas a corrente elétrica. A energia de ativação para a condutividade elétrica em vidros soda-cal-sílica está associada à energia necessária para o íon Na+ transpor a barreira de potencial entre os interstícios adjacentes na rede vítrea. Para determinar a energia de ativação da condutividade elétrica DC, Eσ, destes vidros, submetemos amostras de cada composição a um campo elétrico de 1 MV/m, durante 2 segundos para diferentes temperaturas entre 100 e 220 ºC. Esta energia está relacionada com... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In this work we performed thermal poling in glasses with composition (%mol) 22Na2O.8CaO.65SiO2 .5MO2 (M = Si, Ti, Ge, Zr, Sn and Ce). The thermal poling consist in apply a high intensity DC electric field (~1 MV/m) on samples at high temperatures. During the thermal poling process a permanent electric field is generated in the anode region of the sample, and this field is responsible for nonlinear optical properties of various glasses. We submit to thermal poling samples with ~1.5 mm in thickness and area of 20x20 mm2. We used gold electrodes with a diameter of 1 cm. The samples were heated inside a furnace to ~ 145 oC and an electric field of 1 MV/m was applied for 60 min. During the poling process, we measure simultaneously the current through the circuit and the temperatures in the furnace and of the sample. The electric current of the circuit is related to the migration of sodium ions in the bulk samples from the anode to the cathode. The current decrease with the poling time is due to the formation of a Na+ absent layer (depletion layer) near the anode surface. The different tetravalent cations, M4+, in the glass have different functions in their structures and affect the electrical current in particular manners. The activation energy for electrical conductivity in soda-lime-silica glasses is associated with energy for the Na+ ions to cross the potential barrier, which is submitted to the interstices of the glassy network, and jump into the nearest interstice. The activation energy of DC electrical conductivity, Eσ, of our samples of was determined by applying an electric field of 1 MV/m for 2 seconds, at different temperatures between 100 and 220 ºC. This energy is related to the current, I, through the equation ... The energy calculated is ~0.8 eV. To evaluate the structural and compositional changes of the samples surfaces that were in contact with the ...
Mestre
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Lepicard, Antoine. "Contrôle de la réactivité chimique de surface et des propriétés optiques dans les verres". Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0162/document.
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Le poling thermique est une technique consistant à appliquer un fort champ électrique (DC) à un substrat de verre chauffé. Après traitement, un champ électrique est figé au sein de la matrice vitreuse, brisant sa centrosymmétrie. La présence de ce champ permet d’accéder à des propriétés d’optique nonlinéaire du second ordre, habituellement interdite dans un milieu centrosymmétrique tel que le verre. En plus des propriétés d’optique nonlinéaire, la présence du champ électrique a été associée à des modifications structurelles et compositionnelles mais également à des changements de propriétés de surface. Notre objectif a été d’utiliser cette technique pour modifier les propriétés de réactivité de surface et optique de verres d’oxyde (borosilicate et borophosphate de niobium (BPN)) et de verres de chalcogénures. Après poling, les modifications structurelles ont été caractérisée par spectroscopie vibrationnelle Raman et infrarouge. L’intensité et la localisation du champ électrique ont été caractérisées par des techniques de génération de seconde harmonique (SHG) : une analyse quantitative avec les franges de Maker et une d’imagerie μSHG. Le traitement a permis d’augmenter localement la réactivité de surface du verre borosilicate. Dans les verres BPN et chalcogénures, le traitement a permis de contrôler les propriétés optiques à la fois linéaire et nonlinéaire à l’échelle micrométrique. Ces résultats permettent d’envisager l’utilisation du poling thermique pour des applications en photonique intégréeThermal poling is a technique which consists in the application of a strong DC electric field to a heated glass substrate. Following the treatment, a static electric field is frozen inside the glass matrix, effectively breaking its centrosymmetry. Presence of the electric field allows for second order non-linear optical properties usually forbidden in centrosymmetric medium such as glasses. In addition to nonlinear optical properties, the presence of the electric field has been associated with structural/compositional modifications as well as surface property changes. Our objective was to use this technique to tailor surface reactivity and optical properties in oxide (borosilicate and niobium borophosphate) and chalcogenide glasses. After poling, structural modifications were investigated using Raman and infrared spectroscopy. Strength and localization of the electric field were characterized by Second Harmonic Generation (SHG) techniques: quantitative Maker fringes analysis and μSHG imaging. The treatment has successfully allowed to locally enhanced the surface reactivity of a borosilicate glass. In niobium borophosphate and chalcogenide glasses, the treatment has permitted to control optical properties both linearly and non-linearly at the micrometric scale. These results show that thermal poling could be used to create functional devices for applications in integrated photonics
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Johnson, Eric K. "Low Loss Hybrid Waveguide Electric Field Sensor Based on Optical D-fiber". Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2153.pdf.
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Müller, Rolf-Georg. "Polizeiliche Datenerhebung durch Befragung : zugleich eine Analyse des [Para] 9 nw. PolG /". Berlin : Duncker und Humblot, 1997. http://swbplus.bsz-bw.de/bsz062852353vlg.htm.
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Woodbridge, Paula Lee. "Investigation of pathogenic effects of mutations in the polymerase gamma (POLG) gene". Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/12758.
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The prevalence of polymerase gamma (POLG) variants in an adult population of Australian patients with suspected mitochondrial disease, displaying symptoms commonly associated with POLG-related diseases was determined (Woodbridge et al., 2013). Literature and mutational analysis of the five informative variants identified, revealed two patients with pathogenic variants known to cause POLG-related disease (patient#1: p.T851A and p.P163S; patient#2: p.T851A and p.N468D). Variants in POLG, the catalytic subunit of Mitochondrial DNA polymerase gamma (polγ), can cause aberrant function of the polymerase, which can introduce errors into mtDNA leading to mitochondrial dysfunction. Disturbances in mitochondrial function was analysed in generated neuronal cell models: olfactory neurospheres (ONS) and induced pluripotent stem cell (iPSC)-derived neurons derived from patient#1. Patient#1 ONS showed an increased proportion of cells lacking mtDNA with successive passage, which was associated with decreased ATP production and decreased levels of superoxide presumably due to the absence of a functional respiratory chain. Patient#2 ONS had reduced levels of mtDNA (~50% of control) with successive passaging, but showed no detectable functional changes in the mitochondrial parameters analysed. POLG#1 mutant iPSC-derived neurons showed significantly slower increases in mtDNA content during neural differentiation, which is a mtDNA depletion defect similar to the ONS cell model. The dysfunctional mtDNA replication did not translate into an observable bioenergetic defect. Consequently, the iPSC-derived neurons were challenged with sodium valproate (VPA), an anticonvulsant drug that interferes with mitochondrial function, to uncover the bioenergetic defect in the POLG#1 mutant cells.
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Pitayu, Laras. "Mitochondrial Disorders Linked to mtDNA instability : From Therapy to Mechanism". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112233.
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L’instabilité d’ADN mitochondrial (ADNmt) peut être quantitative avec la déplétion de l’ADNmt ou qualitative avec des délétions de l’ADNmt. Ces anomalies sont une des causes les plus commmunes des maladies mitochondriales. Un des gènes qui contrôle la stabilité et le maintien de l’ADNmt est POLG. Ce gène code pour la polymerase gamma mitochondriale. Chez l’homme, les mutations dans le gène POLG sont liées aux maladies mitochondriales telle que; l’insuffisance hépatique, le syndrome d’Alpers, le PEO ou Progressive External Ophtalmoplegia, la neuropathie sensorielle et l’ataxie. Des mutations dans le gène POLG sont aussi associées au syndrome de Parkinson. Aujourd’hui, il n’existe aucune thérapie pour ces maladies. Compte tenu de la conservation évolutive de la fonction mitochondriale de la levure à l’homme, nous avons utilisé deux organismes modèles, Saccharomyces cerevisiae et Caenorhabditis elegans, pour identifier des molecules chimiques capables de compenser l’instabilité de l’ADNmt liée à des mutations du gène POLG dans des fibroblastes d’un patient. Nous avons trouvé trois molécules candidates potentielles: MRS2, MRS3 et MRS4, à partir d’un criblage primaire chez la levure, en utilisant une chimiothèque d’environ 2000 molécules chimiques. MRS3 est la molécule candidate la plus efficace pour la stabilization d’ADNmt chez des mutants POLG de la levure, du champignon filamenteux, du nématode et sur des fibroblastes de patients. MRS3, ou clofilium tosylate (CLO), est un agent antiarrhytmique, médicament pour soigner les troubles du rythme cardiaque. Dans cette étude, nous avons aussi montré que deux autres antiarrhythmiques appartenant à la même classe que CLO avaient un effet positive chez un mutant POLG de C. elegans. En utilisant une approche de chemogénomique chez la levure, nous avons identifié Fis1, un acteur de la fission mitochondriale qui pourrait être impliqué dans la mode d’action de CLO. Fis1 est requise pour la viabilité cellulaire en concentration légèrement toxique de CLO et nécesaire pour la stabilization de l’ADNmt par CLO. L’ensemble de ces résultats ont montré que CLO pourrait être la première molécule chimique qui stimule la réplication de l’ADNmt et qui pourrait être développée pour le traitement des maladies liées à des mutations dans le gène POLG. Ces résultats ont aussi permis de mettre en évidence une nouvelle connexion entre replication de l’ADNmt et la fission mitochondrialeThe instability of mitochondrial DNA (mtDNA) in form of mtDNA depletion (quantitative instability) or large deletion (qualitative instability) is one of the most common cause of mitochondrial diseases.. One of the genes responsible for human mtDNA stability, POLG, is exploited in this study. POLG encodes the human mitochondrial polymerase gamma. In human, POLG mutations are a major cause of mitochondrial disorders including hepatic insufficiency; Alpers syndrome, progressive external ophthalmoplegia, sensory neuropathy and ataxia. They are also associated with Parkinsonism. Currently, there is no effective and disease-specific therapy for these diseases. Based on the conservation of mitochondrial function from yeast to human, we used Saccharomyces cerevisiae and Caenorhabditis elegans as first pass filters to identify chemical compounds that suppresses mtDNA instability in cultured fibroblasts of a POLG-deficient patient. We found three potential candidates, MRS2, MRS3 and MRS4, from a chemical screening of nearly 2000 compounds in yeast. MRS3 is the most efficacious in stabilizing mtDNA in yeast, filamentous fungi, worm and patient fibroblasts. This unsuspected compound, clofilium tosylate (CLO), belongs to a class of antiarrhythmic agents for cardiovascular disease. Two other antiarrhythmic agents (FDA-approved) sharing common pharmacological properties and chemical structure with CLO also show potential benefit for POLG deficiency in C. elegans. Using a chemogenomic approach in yeast, we also discovered that a mitochondrial fission actor Fis1 is implicated in the mechanism of action of CLO. Fis1 is important for cellular viability in a slightly toxic concentration of CLO and is required for the mtDNA stabilizing potency of CLO. Our findings provide evidence of the first mtDNA-stabilizing compound that may be an effective pharmacological alternative for the treatment of POLG-related diseases and uncover a new connection between the mitochondrial fission process and mtDNA replication
Ketidakstabilan DNA mitokondria (mtDNA) dalam bentuk pengurangan kopi mtDNA di dalam sel (ketidakstabilan kuantitatif), atau pun dalam bentuk delesi pada sekuens mtDNA (ketidakstabilan kualitatif) merupakan salah satu penyebab penyakit mitokondria. Salah satu gen yang bertanggung jawab dalam menjamin kestabilan mtDNA adalah POLG. Gen POLG mengkode protein polimerase gamma pada manusia, yang mereplikasi dan mereparasi mtDNA di dalam mitokondria. Mutasi pada gen POLG dapat menyebabkan penyakit kelainan mitokondria pada manusia, seperti gagal ginjal, sindrom Alpers, Progressive External Ophtalmoplegia, neuropati sensorial, ataxia dan bisa dikaitkan dalam beberapa gejala Parkinsonisme. Saat ini, belum ada terapi obat yang dapat mengatasi penyakit – penyakit tersebut. Berdasarkan kesamaan evolutif dari ragi hingga manusia, pada studi ini kami menggunakan Saccharomyces cerevisiae dan Caenorhabditis elegans untuk mengidentifikasi molekul obat yang berpotensi mengatasi ketidakstabilan mtDNA dari fibroblas pasien manusia yang memiliki mutasi gen POLG. Kami mengidentifikasi tiga kandidat potensial, yakni MRS2, MRS3 dan MRS4 dari penapisan kurang lebih 2000 molekul obat dengan menggunakan ragi. MRS3 adalah kandidat yang paling berkhasiat dan mampu mengatasi ketidakstabilan mtDNA pada ragi, Podospora, cacing dan fibroblas manusia. MRS3 adalah alias bagi clofilium tosylate (CLO), sebuah molekul antiaritmia untuk penyakit kardiovaskuler. Pada studi ini, kami juga menguji aktifitas dua molekul antiaritmia lain yang tergabung dalam kelas yang sama dengan CLO, dan menemukan bahwa kedua molekul ini juga berpotensi mengatasi defisit POLG pada cacing C. elegans. Dengan menggunakan metode kemogenomik pada ragi, kami juga mengidentifikasi sebuah aktor prosesus pembelahan mitokondria, Fis1, yang berpotensi terlibat dalam mekanisme seluler CLO. Fis1 dibutuhkan untuk: (1) kelangsungan hidup ragi pada konsentrasi toksik CLO dan (2) efek CLO dalam menstabilkan mtDNA pada ragi. Keseluruhan studi ini membuktikan potensi CLO sebagai molekul penstabil mtDNA yang pertama, yang dapat dikembangkan sebagai salah satu alternatif terapi obat untuk penyakit – penyakit mitokondria terkait mutasi POLG. Melalui studi ini, juga diungkap adanya hubungan antara kestabilan mtDNA dan prosesus pembelahan mitokondria
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Kayunkid, Navaphun. "Epitaxy of regioregular poly(3-hexylthiophene) : from structure determination to the growth of highly oriented Shish-Kebab fibers". Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAE045.
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Le poly(3-hexylthiophène) régiorégulier (rr-P3HT) est l’un des matériaux phare pour les applications en électronique plastique. Afin d’améliorer les performances des dispositifs, il est important de comprendre et de contrôler la structure et la morphologie de la couche active. Des films minces de rr-P3HT cristallins et orientés peuvent être obtenus par epitaxie directionnelle par cristallisation (DEC) de 1,3,5-trichlorobenzène (TCB). Dans ce travail de thèse, nous présentons les avantages de la méthode DEC pour (i) déterminer la structure cristalline du rr-P3HT et pour (ii) étudier les fibres « shish-kebab », une morphologie alternative du rr-P3HT. La première partie de ce manuscrit consiste en l’analyse structurale par diffraction électronique de la forme I du P3HT obtenue dans les films epitaxiés. Afin d’affiner le modèle structural, nous avons fait varier la conformation des chaînes latérales. Dans un deuxième temps, nous avons appliqué ce même protocole afin de résoudre la structure du second polymorphe du P3HT (forme II) grâce à l’obtention de monocristaux parself-seeding. La deuxième partie du manuscrit est consacrée à l’élaboration de fibres orientées dites en « shish-kebab » par épitaxie dans un mélange TCB/Pyridine. La cinétique de croissance ainsi que l’orientation des chaînes de P3HT sont étudiés afin d’optimiser la méthode de préparation des fibres. L’effet de la masse moléculaire sur leur formation a également été évalué. Finalement les propriétés de transport de charges au sein de ces fibres ont été étudiées grâce à l’élaboration de transistors à effet de champRegioregular poly(3-hexylthiophene) (rr-P3HT) is one of the promising materials for plastic electronic applications. Understanding as well as controlling the structure and morphology of the active layer is essential to improve the device efficiency. Highly crystalline and highly oriented rr-P3HT thin films can be obtained via directional epitaxial crystallization (DEC) in 1,3,5-trichlorobenzene (TCB). In this dissertation, we present the benefits of DEC method to (i) determine the crystal structure of rr-P3HT and (ii) to study shish-kebab fibers, an alternative morphology of rr-P3HT. The first part of this dissertation is related to the structural analysis of rr-P3HT form-I by using electron diffraction analysis on the epitaxied film. Furthermore, the modification of side chain conformation is used to improve the structural model. Finally, the determination protocol is also applied to resolve the preliminary crystal structure of rr-P3HT form II prepared by self-seeding method. The second part of thisdissertation is related to highly oriented shish-kebab fibers of rr-P3HT prepared by epitaxial crystallization in a mixture of TCB and pyridine. The investigations of growth kinetics and orientation of P3HT chains in the fiber are performed in order to determine the optimization of preparation conditions and growth mechanism of the fibers. In addition, the effect of molecular weight on the formation of the fibers is investigated. Finally, the charge transport properties of the fibers are measured by using the field effect transistor configuration
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Ferreira, Brito. "Etudes de la génération de second harmonique dans les verres d'oxydes polarisés thermiquement". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2002. http://tel.archives-ouvertes.fr/tel-00008251.
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Le développement croissant des réseaux de télécommunication de fibre optiques nécessite la mise au point de systèmes optiques intégrés (amplificateurs, switch optique, WDM, DWDM, ...). La découverte de génération de second harmonique dans les verres ouvre de nouvelles perspectives d'application dans le domaine des télécoms. C'est dans ce contexte que nous avons débuté cette thèse par la recherche de nouveaux systèmes vitreux (Nb2O5 – P2O5 – CaO – B2O3 et TeO2 – PbO – P2O5), qui après un traitement de poling présentent une forte susceptibilité non linéaire d'ordre deux. L'étude a porté sur la synthèse, le traitement de poling et les caractérisations physico-chimiques (structurales et optiques) des verres. Une application aux couches minces a été entreprise.
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Fragemann, Anna. "Quasi-Phasematched nonlinear processes in KTiOPO4 isomorphs". Licentiate thesis, KTH, Physics, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1716.
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This thesis explores the use of nonlinear crystals from theKTiOPO4(KTP) family with the aim to extend the possibleapplications for laser sources and to gain more knowledge aboutthe materials benefits and limits. The work focussed onoptical parametric oscillators (OPOs) and optical parametricamplifiers (OPAs), which employ second order nonlinearprocesses. Both devices transfer energy from a laser beam at aparticular wavelength to a different wavelength, which istuneable. In OPOs two new beams at different wavelengths aregenerated, whereas in OPAs an existing weak beam is amplified.The essential part of these devices, which enables theoccurrence of the energy conversion, is a nonlinear crystal. Inthis work the ferroelectric crystals KTP and RbTiOPO4(RTP) have been utilized.
By modifying the materials structure,quasi-phasematching can be obtained, which is a crucialrequirement for achieving efficient energy conversion betweenthe incident and the generated waves. The fabrication ofquasi-phasematched crystals is dependent on the controlledreversion of the materials spontaneous polarisation,which is accomplished by periodic electric field poling.
Nanosecond pulses of more than 200 kW were generated in theeye-saferegion by employing a double pass OPA.Small signal gains exceeding 75 dB were obtained for anessentially diffraction limited beamwithout spectralbroadening of the seed. By subsequent signal coupling intofibres substantial broadening was accomplished. A systematicmeasurement series of several RTP crystals allowed us toaccurately determine the wavelength and temperature dispersionof the refractive index, which are two essential requirementsfor further employment of this material. The OPOs based on RTPwere widely tuneable by controlling the temperature. It wasalso concluded that RTP behaves similar to KTP in parametricdevices, thus being a material, which can sustain high powers,possesses large nonlinear coefficients and can operate in abroad wavelength region.Efficient Raman oscillation concurrent with parametricoscillation was observed and analysed in several KTP samples.This gave further insight into the processes taking placeinside the material when performing as a frequency converter,if the generated idler lies in the absorption band.This thesis also covers the investigation of afemtosecond optical parametric chirped pulse amplifier.Temporally stretched seed pulses were amplified to 85 µJ,resulting in a gain above 60 dB, and subsequent recompressionresulted in 270 fs pulses.
Keywords:nonlinear optics, KTiOPO4, optical parametric oscillator, optical parametricamplifier, RbTiOPO4, quasi-phasematching, electric field poling,stimulated Raman scattering.
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Escanhoela, Júnior Carlos Augusto [UNESP]. "Condutividade elétrica e polarização térmica de vidros soda-cal-sílica contendo diferentes cátions tetravalentes". Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/91918.
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escanhoelajunior_ca_me_rcla.pdf: 2205069 bytes, checksum: 07cd01b4a104f262986c24bd2a7f874b (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Neste trabalho realizamos a polarização térmica em vidros silicatos com composição (%mol) 22Na2O.8CaO.65SiO2 .5MO2 (M = Si, Ti, Ge, Zr, Sn e Ce). A polarização térmica consiste em aplicar um campo elétrico DC de elevada intensidade (~1 MV/m) em amostras a altas temperaturas. Durante a polarização térmica é gerado um campo elétrico permanente no interior da amostra, na região do anodo, que é responsável por propriedades ópticas nãolineares. Submetemos à polarização térmica amostras dos vidros, com ~1,5 mm de espessura e área de 20 x 20 mm2. Utilizamos eletrodos de Au, com diâmetro de 1 cm. As amostras foram aquecidas no interior de um forno até ~145 oC e aplicamos um campo elétrico de 1 MV/m durante 60 min. Durante a aplicação do campo elétrico, medimos simultaneamente a corrente através do circuito e as temperaturas no forno e na amostra. A corrente elétrica medida no circuito está relacionada com a migração de íons Na+ no interior das amostras do anodo para o catodo. A diminuição da corrente após um determinado tempo de polarização é devido à formação de uma camada com ausência de íons Na+ (camada de depleção) junto ao anodo. Os diferentes cátions tetravalentes, M4+, inseridos no vidro têm funções particulares na estrutura deste e afetam de formas distintas a corrente elétrica. A energia de ativação para a condutividade elétrica em vidros soda-cal-sílica está associada à energia necessária para o íon Na+ transpor a barreira de potencial entre os interstícios adjacentes na rede vítrea. Para determinar a energia de ativação da condutividade elétrica DC, Eσ, destes vidros, submetemos amostras de cada composição a um campo elétrico de 1 MV/m, durante 2 segundos para diferentes temperaturas entre 100 e 220 ºC. Esta energia está relacionada com...
In this work we performed thermal poling in glasses with composition (%mol) 22Na2O.8CaO.65SiO2 .5MO2 (M = Si, Ti, Ge, Zr, Sn and Ce). The thermal poling consist in apply a high intensity DC electric field (~1 MV/m) on samples at high temperatures. During the thermal poling process a permanent electric field is generated in the anode region of the sample, and this field is responsible for nonlinear optical properties of various glasses. We submit to thermal poling samples with ~1.5 mm in thickness and area of 20x20 mm2. We used gold electrodes with a diameter of 1 cm. The samples were heated inside a furnace to ~ 145 oC and an electric field of 1 MV/m was applied for 60 min. During the poling process, we measure simultaneously the current through the circuit and the temperatures in the furnace and of the sample. The electric current of the circuit is related to the migration of sodium ions in the bulk samples from the anode to the cathode. The current decrease with the poling time is due to the formation of a Na+ absent layer (depletion layer) near the anode surface. The different tetravalent cations, M4+, in the glass have different functions in their structures and affect the electrical current in particular manners. The activation energy for electrical conductivity in soda-lime-silica glasses is associated with energy for the Na+ ions to cross the potential barrier, which is submitted to the interstices of the glassy network, and jump into the nearest interstice. The activation energy of DC electrical conductivity, Eσ, of our samples of was determined by applying an electric field of 1 MV/m for 2 seconds, at different temperatures between 100 and 220 ºC. This energy is related to the current, I, through the equation ... The energy calculated is ~0.8 eV. To evaluate the structural and compositional changes of the samples surfaces that were in contact with the ...
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Müller, Rolf-Georg [Verfasser]. "Polizeiliche Datenerhebung durch Befragung. : Zugleich eine Analyse des § 9 nw. PolG. / Rolf-Georg Müller". Berlin : Duncker & Humblot, 2019. http://d-nb.info/1238279430/34.
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Correia, Renata de Luizi. "Alterações metabólicas e o papel da mitocôndria no processo de tumorigênese de astrocitomas humanos". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/5/5138/tde-25052010-162000/.
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As mitocôndrias desempenham um papel fundamental na sobrevivência e morte celular. Alterações do DNA mitocondrial (DNAmt) - como, por exemplo, amplificação, mutação homoplásmica, deleção e depleção -, bem como suas implicações clínico-patológicas, tem sido analisadas em inúmeras neoplasias humanas. No intuito de se pesquisar alterações mitocondriais associadas à tumorigênese, o presente trabalho teve como objetivos analisar a expressão de genes implicados no metabolismo energético e envolvidos na replicação e transcrição mitocondriais, quantificar o número de organelas mitocondriais e de cópias de DNAmt e analisar a expressão dos genes em astrocitomas de diferentes graus de malignidade (23 OMS grau I, 26 grau II, 18 grau III e 84 grau IV ou GBM) em relação ao tecido cerebral não tumoral (22 amostras). As expressões relativas dos genes selecionados, bem como as quantificações relativa e absoluta do DNA mitocondrial, foram realizadas por PCR em tempo real. O aumento de expressão relativa de genes-chave da via glicolítica, alterações nos níveis de expressão dos genes do ciclo dos ácidos tricarboxílicos e hipoexpressão de genes da fosforilação oxidativa detectados corroboraram o efeito Warburg. Foi demonstrado que a redução do número de cópias do DNAmt está associada com o grau de malignidade dos astrocitomas difusamente infiltrativos, sendo GBM o mais depletado e independente do número de organelas. As médias observadas para tecido não tumoral, astrocitoma grau I, grau II, grau III e GBM foram, respectivamente, 1,28, 0,26, 0,45, 0,42 e 0,17. Níveis aumentados de expressão relativa dos genes dos fatores de transcrição mitocondriais A (TFAM), B1 (TFB1M), B2 (TFB2M) e da subunidade catalítica da polimerase mitocondrial (POLG) foram detectados em todos os graus de astrocitomas, exceto TFB2M em astrocitoma grau II. Embora exista forte correlação entre os fatores de transcrição mitocondriais, somente os níveis de expressão de POLG se correlacionaram inversamente com o número de cópias de DNAmt. A expressão elevada de TFAM está associada a uma maior sobrevida no grupo de pacientes com GBM, interpretada como compensatório. As hiperexpressões de TFAM e POLG estão relacionadas a um melhor prognóstico em pacientes com GBM. Embora nossos achados da disfunção do metabolismo intermediário e depleção do DNAmt em astrocitomas corroborem a literatura, ainda não está bem esclarecida sua implicação na iniciação e manutenção da transformação maligna. Investigações futuras são necessárias para o esclarecimento destas questões.Mitochondria has a key role in cell survival and death. Mitochondrial DNA (mtDNA) alterations, for example, amplification, homoplasmic mutation, deletion and depletion, and their clinical and pathological implications have been analyzed in human malignancies. In order to search for mitochondrial alterations associated to tumorigenesis, this study aimed to analyze the expression levels of genes involved in energetic metabolism, and in mitochondrial replication and transcription, to quantify the number of mitochondrial organelle and mtDNA copy number in astrocytomas of different grades of malignancy (23 WHO grade I, 26 grade II, 18 grade III and 84 grade IV or GBM) related to non-neoplastic brain tissue (22 samples). The relative expression level of the selected genes as well as the relative and absolute quantification of mtDNA were performed by real-time PCR. Relative expression increase of glycolytic pathway key genes, change of citric acid cycle genes and hipoexpression of oxidative phosphorylation genes were detected, and confirmed the presence of Warburg effect. The reduced mtDNA copy number was associated to the grade of malignancy of diffusely infiltrating astrocytoma, being GBM the most depleted, and not related to parallel decrease in the number of organelle. The mean mtDNA copy number for non neoplastic tissue, astrocytoma grade I, grade II, grade III and GBM were respectively 1.28, 0.26, 0.45, 0.42 and 0.17. The increased relative gene expression of mitochondrial transcription factor A (TFAM), B1 (TFB1M), B2 (TFB2M) and the catalytic subunit of mitochondrial polymerase (POLG) were observed in all grades of astrocytoma, except TFB2M in grade II astrocytoma. Although a strong correlation was observed among the mitochondrial transcription factors, only the expression level of POLG correlated inversely to the mtDNA copy number. The overexpression of TFAM was associated with long-term survival in the GBM patients and interpreted as compensatory. TFAM and POLG overexpressions were related to better prognosis in GBM patients. Although our findings concerning the impairment of intermediary metabolism and depletion of mtDNA in astrocytomas confirmed previous reports, their role in initiation or maintenance of malignant transformation were not fully understood. Further investigations are needed to clarify these issues.
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Henderson, Ashleigh. "Mapping the security arrangements for Khayelitsha's schools: what are the normative and functional outcomes of a nodal policing approach to poling school-based violence in Khayelitsha?" Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15199.
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In light of the contextual realities of school violence, the aim of this paper is to provide an analytical map of the security arrangements at schools in a particular area, namely Khayelitsha. The question is not whether these arrangements are failing (as will be made clear by the evidence provided in chapter four) but rather why and how they are failing. The task of identifying these gaps in an accurate and sufficiently nuanced way would be impossibly large if the scope of the study were all schools in South Africa. Furthermore, in order to be able to make precise recommendations and implement effective interventions, it is necessary to have a thorough understanding of the particular issues faced by particular schools, rather than schools in general. As such, I have chosen to narrow the scope of the study to one area where violence in schools has been shown to be particularly prevalent. The area in question is a large township located on the outskirts of the City of Cape Town called Khayelitsha. This area has been chosen not only to narrow the scope of the study, but also because policing in Khayelitsha has recently been the topic of an extensive Commission of Inquiry.
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Luo, Jingdong, Dong Hun Park, Roland Himmelhuber, Zong-Long Zhu, Ming Li, Robert A. Norwood e Alex K.-Y. Jen. "Efficient wafer-scale poling of electro-optic polymer thin films on soda-lime glass substrates: large second-order nonlinear coefficients and exceptional homogeneity of optical birefringence". OPTICAL SOC AMER, 2017. http://hdl.handle.net/10150/624966.
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We demonstrate a simple protocol for repeatable and efficient contact poling of guest-host electro-optic (EO) polymer thin films over large areas on soda-lime glass substrates. The poled large-area (up to 13.5 cm(2)) thin films in this study exhibit very large second-order nonlinear susceptibilities (d(33) values of 330-520 pm/V) for second-harmonic generation (SHG) and associated large Pockels coefficients (r(33) values of 105-180 pm/V) at the wavelength of 1.3 mu m. The poling protocol also produced poled EO thin films with excellent optical homogeneity and large positive birefringence with small variation (similar to 10(-3)) of refractive indices over the poled large areas. The study suggests a viable and scalable path towards the realization of integrated photonics based on pre-poled thin films of high performance EO polymers. (C) 2017 Optical Society of America
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Tombelaine, Vincent. "Etude de rayonnements à large bande spectrale induits dans les fibres optiques microstructurées air-silice". Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/3a75631c-da2c-4abb-922b-d1d032113bf1/blobholder:0/2007LIMO4023.pdf.
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Les travaux reportés dans ce manuscrit de thèse portent sur la génération de supercontinua dans les fibres optiques microstructurées air-silice. Le développement d’un nouveau système basé sur une double excitation de la fibre non linéaire (fondamental et harmonique) a permis l’obtention d’un supercontinuum dans le domaine infrarouge et visible. Après une étude systématique du phénomène, il a été montré que l’élargissement dans l’infrarouge était induit par une propagation soliton et que le continuum visible était généré par un effet de modulation de phase croisée. Deux nouvelles méthodes innovantes, issues de ces premières investigations, sont présentées. La première technique utilise la génération de second harmonique obtenue directement dans la fibre. La seconde technique est basée sur un mélange à quatre ondes intermodal particulier. Ces études ont été réalisées pour le développement d’outils de diagnostic pour la cytométrie de flux et l’imagerie non linéaire CARSThe investigations reported here concerns the generation of supercontinua in air-silica microstructured optical fibres. The development of a new system based on a double excitation (fundamental and harmonic) of nonlinear fibre allowed to obtain a supercontinuum in the infra-red and visible range. After a systematic study of the phenomenon, it was shown that the broadenings in the infra-red and in visible domains were generated by soliton propagations and cross phase modulation respectively. Then two new innovating methods, resulting from the double pumping device, were demonstrated. The first technique uses the second harmonic generation obtained directly in the fibre. The second one is based on a particular intermodal four wave mixing. These studies were carried out for the development of diagnosis tools for the flow cytometry and the nonlinear CARS imaging
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Tzeng, Yu-Yi, e 曾鈺懿. "Comparison of forward and backward second harmonic generation in poling and non-poling area of PPLN". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/xk5d2x.
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碩士國立臺灣大學
物理研究所
99
In recent years, laser has been wildly used in many applications. Because of the lack of laser source in certain wavelength, generating new light source in nonlinear materials by the quasi-phase matching technique (QPM) becomes one of the most important methods. Periodically poled crystal (PPC) is one of the most attractive materials in nonlinear optics due to its high nonlinear conversion efficiency. Good crystal structure leads to good nonlinear conversion efficiency. However, the crystal quality is only judged by observing spatial stability of the period before. There has been no study tries to give the internal micro-crystal structure information in both poling and non-poling domains of periodically poled crystals. Note that molecular structure of crystal affects second harmonic generation (SHG) signals, we choose second harmonic microscopy to observe PPC. Both the forward and backward second harmonic images are analyzed. In this study, we prove that the crystal structure is changed during poling process and also discussed the relation between the applied electric field in the process and the SHG intensity in PPLN. Furthermore, we compare the SHG performance between poling and non-poling domains in both forward and backward channels and pointed out the difference between these two domains. We believe that this study is very helpful for the improvement in fabrications of PPC in the future.
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Lin, Yu-Hung, e 林弘育. "Local Periodical Poling on Z-cut LiNbO3". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/fnkc9m.
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碩士國立臺北科技大學
光電工程系研究所
99
In this thesis , we study the local periodically poled on the Z-cut lithium niobate ridge structure. When design in polarization reversal electrode, using the finite element method to analysis, and calculate the applied voltage on the electrode of the ridge structure caused the electric field distribution in lithium niobate. Then infer the initial polarization reversal region. We discuss the different electrode structures, electrode width, electrode spacing, the thickness of silicon dioxide impact electric field distribution. And desire to enhance the uniformity of electric field distribution, the number of peak electric field making reversal region at the same time lithium niobate ridge. As transverse polarization reversal, reached the purposes of entire region reversal in the ridge structure . At the first, we use the proton exchange method after etching in lithium niobate, for fabrication the ridge structure on +Z surface in this experiment. In the next, we fabricate periodically silicon dioxide pattern and titanium film to form the desired electrode structure. The three electrode structure such as, sheet electrodes, three micron stripe electrodes, and multiple nano stripe electrodes. Two of the former we use optical lithography and lift-off methods to produce the electrode patterns.The nano-electrodes structure is made by electron beam lithography and inductive coupled plasma etching technique to produce a nano-groove of the insulating silicon oxide layer, then sputter titanium film to form the nano-electrode structure. When a voltage is applied to ridge structure on the periodic electrode, the lithium niobate surface can be poled . Three electrode structure required for polarization reversal voltages are 400V, 140V and 160V, respectively . And discuss the process parameters for the poled results.
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Gunawan, Hariyanto, e 魏福勝. "A New Poling Method for Piezoelectric Materials". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/8wx638.
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博士中原大學
機械工程研究所
102
Abstract Piezoelectric materials have been proposed and utilized for many sensors and actuators application due to good piezoelectric and ferroelectric characteristic, high electromechanical coefficient, relative dielectric constant, and good response. Ceramics and polymers are the most popular piezoelectric materials that have found to display piezoelectric response. Among the fabrication processes, polarization is the most important that it nearly dominates the performance of piezoelectric materials. In this dissertation, a new polarization method using ITO (Indium Tin Oxide) glass is proposed. Different from the conventional poling method using metal electrode coated onto piezoceramic or polyvinylidene fluoride (PVDF), ITO glass is used as electrode to transmit the electric field voltage into piezoceramic or PVDF for poling. With the advantage of applying higher electric field in the process of polarization and eliminating the occurrence of flashover and arcing efficiently, this approach can thus make piezoceramic or PDVF material gain better electric output response. Construction design of ITO poling method, fabrication and characterization of properties of piezoceramic and PVDF are investigated and discussed. Comparison of piezoelectricity with conventional poling method is carried out using Fourier Transformed Infrared Spectroscopy (FTIR), Differential Scanning Calorimeter (DSC), X-ray Diffraction (XRD), and Scanning Electron Microscope (SEM) apparatus. Piezoelectric constant d33, g33 and electricity output response are measured in the experiment, which indicates that ITO poling glass method provides better piezoelectric characteristic for both piezoceramic and PVDF material in comparison with conventional poling method.
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"Poling dynamics of nonlinear optical guest-host polymer systems". 2006. http://library.cuhk.edu.hk/record=b5893043.
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To Chi Wing = 具非線性光學性質客體-主體聚合物系統的極化動力學研究 / 杜志榮.Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (leaves 102-104).
Text in English; abstracts in English and Chinese.
by To Chi Wing = Ju fei xian xing guang xue xing zhi ke ti-zhu ti ju he wu xi tong de ji hua dong li xue yan jiu / Du Zhirong.
Table of contents
Acknowledgements --- p.ii
Abstract --- p.iii
Chinese Abstract --- p.iv
Table of Contents --- p.v
List of Figures --- p.viii
Chapter Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Fundamental of nonlinear optics --- p.2
Chapter 1.2 --- Centrosymmetry and even-order nonlinear susceptibilities --- p.4
Chapter 1.3 --- Generation of second harmonic radiation --- p.5
Chapter 1.4 --- Tensor properties of the nonlinear susceptibilities --- p.7
Chapter 1.5 --- Relationship between macroscopic and microscopic nonlinear susceptibility for a poled polymer --- p.8
Chapter 1.6 --- Outline of the thesis --- p.12
Figures --- p.13
Chapter Chapter 2 --- Poling and Relaxation of Guest-host Polymeric System --- p.15
Chapter 2.1 --- Guest-host nonlinear optical polymeric systems --- p.15
Chapter 2.1.1 --- Photoisomerization of Azobenzene --- p.16
Chapter 2.1.2 --- Disperse Red-1 --- p.17
Chapter 2.1.3 --- Poly (methyl methacrylate) --- p.18
Chapter 2.2 --- Poling techniques --- p.19
Chapter 2.2.1 --- Thermal Assisted Electric-field Poling --- p.19
Chapter 2.2.2 --- Photo-assisted Electric-field poling --- p.22
Chapter 2.2.3 --- All-Optical Poling --- p.25
Chapter 2.3 --- Relaxation of poled nonlinear optical polymers --- p.27
Figures --- p.31
Chapter Chapter 3 --- Experimental Methods --- p.36
Chapter 3.1 --- Sample Preparation --- p.36
Chapter 3.2 --- Experimental Setup --- p.38
Chapter 3.2.1 --- Laser system --- p.38
Chapter 3.2.2 --- The reference arm --- p.39
Chapter 3.2.3 --- The sample arm --- p.40
Chapter 3.2.4 --- Data acquisition (DAQ) system --- p.41
Chapter 3.2.5 --- Temperature control --- p.42
Chapter 3.3 --- Poling and the erasing of thermal history --- p.43
Chapter 3.3.1 --- All Optical Poling --- p.43
Chapter 3.3.2 --- Eecteic Poling --- p.44
Chapter 3.3.3 --- Erasure of thermal history --- p.45
Figures --- p.46
Chapter Chapter 4 --- Experimental results and discussions --- p.51
Chapter 4.1 --- Reliability and reproducibility --- p.51
Chapter 4.2 --- Features of different poling techniques --- p.52
Chapter 4.2.1 --- Sub-Tg electric Poling --- p.53
Chapter 4.2.2 --- Thermal assisted electric Poling --- p.54
Chapter 4.2.3 --- Photo assisted electric Poling --- p.55
Chapter 4.3 --- Relaxation of poling induced x(2) --- p.56
Chapter 4.4 --- Effect of physical aging on the relaxation of PAP induced x{2) --- p.58
Chapter 4.4.1 --- Origin of physical aging and its effect on relaxation --- p.58
Chapter 4.4.2 --- Effect of aging on the relaxation of a PAP sample --- p.59
Chapter 4.5 --- Onset studies of photo-induced free volume --- p.61
Chapter 4.6 --- Comparative studies of TAP and PAP induced x{2) --- p.62
Chapter 4.6.1 --- Secondary Poling --- p.63
Chapter 4.6.1.1 --- Model for describing the temporal behavior of secondary poling --- p.65
Chapter 4.6.1.2 --- Experimental details of the secondary poling measurement --- p.68
Chapter 4.6.1.3 --- Results and Discussion on secondary poling of sample poled by TAP or PAP --- p.69
Chapter 4.6.2 --- Onset of second harmonic signal during electric poling --- p.71
Chapter 4.7 --- Charge injection studies --- p.73
Figures --- p.77
Chapter Chapter 5 --- Conclusion --- p.98
References --- p.101