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1
Myers, Terry W. "Tuning wavelength selective birefringent optical fiber filters using twist birefringence." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 1991. http://digitalcommons.auctr.edu/dissertations/3739.
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A novel physical tuning mechanism for optical fiber filters is proposed and studied. To explore tuning mechanisms, a theoretical model of a Sole birefringent fiber filter is described. The coherency equation of motion for a birefringent filter is solved by transforming to the Stokes-Mueller matrix equation via the measurable Stokes parameters. The Mueller matrix is then expanded in a Taylor series using the generators of the Lorentz transformations. The Stokes vectors and Mueller matrices provide a theoretical formalism which is used to simulate an experimental set-up and to describe the transmission of light through a birefringent fiber filter system. Hence, the theoretical expression for the transmission spectra incident on a detector is derived. This expression is then transformed to the more convenient fourier series form. This form is used to determine the particular type of perturbation necessary to tune a filter. Specifically, a tuning mechanism utilizing twist birefringence is proposed and analyzed. Moreover, we show using theoretical and computer simulation studies that twist birefringence tunes a filter spectra over a narrow but usable range, provided each stage in the filter is twisted at the same rate. For example, a twist birefringence of 85.7 rad/m generated a 42.8 nm tuning range on the filter spectra of a three-stage Sole-type fiber filter when each optical fiber stage is linearly birefringent with a beat length of 18.94 mm at 1282 nm.
2
Geday, Morten A. "Birefringence imaging." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365446.
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3
Pajdzik, Lucjan Adam. "Three-dimensional birefringence imaging." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442916.
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Raynolds, James E. "Strain-induced birefringence in GaAs /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487859879941051.
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5
Harrison, Neil J. "Laser induced birefringence in pure liquids." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305404.
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6
Schuh, R. E. "Characterisation of birefringence in optical fibres." Thesis, University of Essex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363546.
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7
Ahmed, S. U. "Polarisation coupling in high birefringence fibres." Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313837.
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8
Hinds, Ian Charles. "Characterisation of colloids by electric birefringence." Thesis, London South Bank University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336307.
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9
Strack, Florian. "Birefringence and elasticity of overstreched DNA /." [S.l. : s.n.], 1999. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8575309.
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Strack, Florian. "Birefringence and elasticity of overstretched DNA." [S.l.] : Universität Konstanz , Fakultät für Physik, 1999. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8501020.
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11
Poon, Wilson Che-kei. "Raman and birefringence studies of phase transitions." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293634.
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12
Parish, Amanda Jane. "High Birefringence Liquid Crystals for Optical Communications." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3199.
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High birefringence ([delta]n>0.4) nematic liquid crystals are particularly attractive for infrared applications because they enable a thinner cell gap to be used for achieving fast response time and improved diffraction efficiency. In this thesis, the mesomorphic and electro-optic properties of several new fluorinated isothiocyanate (NCS) terphenyl and phenyl tolane single compounds and mixtures are reported. The single compounds demonstrated [delta]n~0.35-0.52 in the visible spectral region at room temperature and exhibit relatively low viscosity. It was found that lateral fluorine substitutions and short alkyl chains eliminate smectic phase and lower the melting temperature of the single compounds. However, the consequence of using highly conjugated compounds to improve electro-optic properties is that the nematic phase is exhibited at high temperatures, over 100[degrees]C, and therefore single compounds cannot be used for device applications. Therefore, several mixtures based on the terphenyl and phenyl-tolane compounds were formulated and evaluated. The purpose of mixtures is to find the optimum balance between electro-optic performance and the mesomorphic properties that determine the operating temperature range. It was found that mixture formulations greatly improved mesomorphic properties to produce nematic phase at or near room temperature and suppressed smectic phase to below 0[degrees]C or eliminating completely. The analysis presented evaluates the benefits of lowering the operating temperature versus the consequence of degrading the electro-optic properties.M.S.
Optics and Photonics
Optics and Photonics
Optics MS
13
Wen, Chien-Hui. "High Birefringence and Low Viscosity Liquid Crystals." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3206.
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In this dissertation, liquid crystal (LC) materials and devices are investigated in order to meet the challenges for photonics and displays applications. We have studied three kinds of liquid crystal materials: positive dielectric anisotropic LCs, negative dielectric anisotropic LCs, and dual- frequency LCs. For the positive dielectric anisotropic LCs, we have developed some high birefringence isothiocyanato tolane LC compounds with birefringence ~0.4, and super high birefringence isothiocyanato biphenyl-bistolane LC compounds with birefringence as high as ~0.7. Moreover, we have studied the photostability of several high birefringence LC compounds, mixtures, and LC alignment layers in order to determine the failure mechanism concerning the lifetime of LC devices. Although cyano and isothiocyanato LC compounds have similar absorption peaks, the isothiocyanato compounds are more stable than their cyano counterparts under the same illumination conditions. This ultraviolet-durable performance of isothiocyanato compounds originates from its molecular structure and the delocalized electron distribution. We have investigated the alignment performance of negative dielectric anisotropic LCs in homeotropic (vertical aligned, VA) LC cell. Some (2,3) laterally difluorinated biphenyls, terphenyls and tolanes are selected for this study. Due to the strong repulsive force between LCs and alignment layer, (2,3) laterally difluorinated terphenyls and tolanes do not align well in a VA cell resulting in a poor contrast ratio for the LC panel. We have developed a novel method to suppress the light leakage at dark state. By doping positive [Delta][epsilon] or non-polar LC compounds/mixtures into the host negative LC mixtures, the repulsive force is reduced and the cell exhibits an excellent dark state. In addition, these dopants increase the birefringence and reduce the viscosity of the host LCs which leads to a faster response time. Dual-frequency liquid crystal exhibits a unique feature that its dielectric anisotropy changes from positive to negative when we increase the operating frequency. Submillisecond response time can be achieved by switching the frequency of a biased voltage, rather than switching the voltage at a given frequency. In this dissertation, we investigate the dielectric heating effect of dual-frequency LCs. Because the absorption peak of imaginary dielectric constant occurs at high frequency region (~ MHz), there is a heat generated when the LC cell is operated at a high frequency voltage. To measure the transient temperature change of the LC inside the cell, we have developed a non-contact method by utilizing the temperature-dependent birefringence property of the LC. Most importantly, we have formulated a new dual-frequency LC mixture which greatly reduces the dielectric heating effect while maintaining good physical properties. Another achievement in this thesis is that we have developed a polarization independent phase modulator by using a negative dielectric anisotropic LC gel. With ~20 % of polymer mixed in the LC host, the LC forms polymer network which, in turn, exerts a strong anchoring force to the neighboring LC molecules. As a result, the operating voltage increases but the response time is significantly decreased. On the phase shift point of view, our homeotropic LC gel has ~0.08 [pi] phase shift, which is 2X larger than the previous nano-sized polymer-dispersed liquid crystal droplets. Moreover, it is free from light scattering and requires a lower operating voltage. In conclusion, this dissertation provides solutions to improve the performance of LC devices both in photonics and displays applications. These will have great impacts in defense and display systems such as optical phased array, LCD TVs, projectors, and LCD monitors.Ph.D.
Other
Optics and Photonics
Optics
14
Honeywood, Mark Jason. "Acoustically induced birefringence in rigid particle suspensions." Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329325.
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Lingard, R. J. "Optical activity in the presence of linear birefringence." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239284.
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16
Zhou, Shun Hua. "Photo-induced birefringence in single-mode optical fiber." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07112009-040515/.
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Geffroy, Aguilar Enrique Leal L. Gary Leal L. Gary. "Birefringence of polymer solutions in time dependent flows /." Diss., Pasadena, Calif. : California Institute of Technology, 1990. http://resolver.caltech.edu/CaltechETD:etd-02232007-154744.
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Tatham, Jennifer Patricia. "Extensional flow dynamics of macromolecules of different flexibilities in solution." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358007.
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Shakos, John Dimitri. "The importance of birefringence in holography with photorefractive polymers." Thesis, University of Manchester, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488416.
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Watson, Rupert M. J. "Electric field birefringence and light scattering of polydisperse colloids." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306817.
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21
Waterman, David. "An automated electric birefringence apparatus for particle size measurement." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277205.
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22
Zhou, Yating. "Advancing fundamentals and applications of X-ray birefringence imaging." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/113810/.
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This thesis is mainly focused on the new technique of X-ray Birefringence Imaging (XBI). It reports applications of XBI in different research areas and also presents some developments of the fundamental theory of XBI analysis. At the end of the thesis, work on crystal structure determination directly from powder X-ray diffraction data is also included. Chapter 1 and Chapter 2 provide the theoretical background of XBI and introduce the other techniques used in this thesis. As XBI is analogous to Polarizing Optical Microscopy (POM), the introduction begins with a discussion of general optics, which is then expanded to specific case of polarized X-rays. The methodology for structure determination directly from powder X-ray diffraction data is also described. Chapter 3 demonstrates the application of XBI to study liquid crystalline materials, representing the first investigation of liquid-state samples by XBI. The experimental results show that the XBI technique is successful to elucidate the molecular orientational ordering in different liquid crystalline phases, demonstrating that characterization of molecular orientations by XBI is not limited to the solid-state. Chapter 4 explores a novel type of material – bending crystals. As an effective technique to investigate molecular orientations, XBI is shown to provide clear information on the crystal curvature. Both plastic and elastic types of bending crystal are analysed in both static and dynamic experiments. A theoretical analysis of XBI behaviour of a material containing multiple molecular orientations is also established. In Chapter 5, XBI is used to study composite organic materials. The experimental results vindicate the ability of XBI to characterize spatial distribution of molecules in composite samples. Chapter 6 reports XBI behaviour for the novel case in which two different crystals with independent orientations are present in the X-ray beam. The development of an experimental set-up for recording XBI data using a transmission-based polarization analyzer is also reported for the first time. Chapter 7 is focused on structure determination directly from powder X-ray diffraction. Three crystal structures are determined – two different urea co-crystals and one poly-aromatic compound. Chapter 8 summarises the work in this thesis, gives an appraisal of the strengths and limitations of the XBI technique, and proposes some potential research directions for the future.
23
COSTEUX, STEPHANE. "Etude par birefringence d'ecoulement de solutions semidiluees de polymeres." Paris 6, 1999. http://www.theses.fr/1999PA066127.
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Les solutions semidiluees de polymeres sont aujourd'hui utilisees dans nombre d'applications industrielles qui necessitent des fluides relativement visqueux qui fluidifient sous cisaillement, comme dans l'industrie alimentaire ou pour la recuperation assistee du petrole. Afin d'obtenir les proprietes rheologiques desirees, il est primordial de comprendre quels mecanismes microscopiques en sont a l'origine. La birefringence d'ecoulement est de ce point de vue une technique interessante, puisqu'elle permet d'evaluer l'orientation et la deformation moleculaires souvent a l'origine de la rheofluidification. Une part importante de ce travail a ete consacree a la conception et la realisation d'un ellipsometre, qui a ete adapte a un rheometre commercial de facon a mesurer simultanement les grandeurs rheologiques habituelles, la birefringence et l'angle d'extinction. On a montre theoriquement qu'une modification du montage permettait egalement d'effectuer ces mesures lorsque l'echantillon possede un pouvoir rotatoire, et on propose un protocole experimental permettant de separer ce pouvoir rotatoire de la birefringence, ce qui permettra l'etude ulterieure de la prise en gel de la gelatine sous cisaillement. Des mesures de birefringence d'ecoulement ont ete realisees sur des solutions semidiluees d'echantillons aux proprietes diverses : - la gomme xanthane, qui est un polysaccharide charge relativement rigide s'orientant aisement sous cisaillement. - le polyoxyethylene dont la grande flexibilite permet en regime semidilue enchevetre une orientation et une deformation importante. - le poly(styrene sulfonate) enfin qui est un polyelectrolyte fortement charge, au squelette hydrophe, et dont les solutions semidiluees en l'absence de sel ajoute montrent tres peu d'orientation, et une tres faible rheofluidification, ce qui peut corroborer des modeles recents de collapse des polyelectrolytes fortement charges, sous l'effet d'une condensation des contre-ions a forte concentration. On a compare ces resultats aux modeles de solutions de batonnets, de chaines flexibles ou persistantes pour le coefficient de diffusion de rotation et la viscosite a bas gradient. . Les ecarts observes entre theories et experiences sont mises au compte de la polydispersite et de la flexibilite.
24
HASMONAY, ERIC. "Birefringence magneto-optique statique et dynamique de colloides magnetiques." Paris 6, 1998. http://www.theses.fr/1998PA066161.
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Les ferrofluides sont des suspensions colloidales de nanoparticles monodomaines magnetiques dont les grains, synthetises chimiquement, sont constitues de ferrite. Ils portent un moment magnetique et sont birefringents du fait d'une anisotropie optique intrinseque. Une densite superficielle de charge permet de les disperser dans un solvant polaire. L'etat de stabilite de la solution depend du ph. Pour une densite superficielle de charge maximale, un sol stable est obtenu. Pour des densites de charges plus faibles, nous observons la formation d'un gel thixotrope puis une floculation reversible au voisinage du point de charge nulle. Un modele de potentiel d'interaction de paires (dlvo) explique dans l'ensemble le diagramme de phase de ces solutions en fonction du ph. Nous realisons premierement une etude magneto-optique statique de sols stables qui nous permet de montrer que, pour des particules a base de -fe 2o 3, la presence d'une couche de spins desordonnes en surface est a l'origine d'une anisotropie optique uniaxiale, conduisant a une birefringence positive. Pour des grains a base de nife 2o 4, cette couche superficielle a un role important dans l'aimantation globale du materiau. Ces nanoparticules sont utilisees comme sondes rheologiques de leur milieu porteur. Trois experiences dynamiques de birefringence magnetique sont realisees avec trois types de champs magnetiques : champ statique module transversalement, alternatif ou pulse. Selon la hierarchie respective de l'energie magnetique, de l'energie d'anisotropie et de l'energie d'agitation thermique des particules, on observe trois regimes avec chacun un temps caracteristique propre. Le montage en champ pulse est aussi utilise pour explorer les proprietes de la phase gel thixotrope en fonction du temps et du ph. Deux effets antagonistes participent au processus de gelification, l'augmentation de la taille des agglomerats libres de tourner dans la solution et leur piegeage progressif sur un agregat de taille infinie.
25
Jenkins, D. M. "The quadrupole moment of dipolar molecules : field-gradient-induced birefringence." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377834.
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Zhang, Jian. "Nonlinear methods for distributed sensing in high birefringence optical fibres." Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300417.
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Wilson, Stephen Ronald. "The characterisation of colloids and macromolecules by linear magnetic birefringence." Thesis, London South Bank University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245149.
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Nash, M. E. "Transient electric birefringence of the micellar region of aqueous monionic surfactants." Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376207.
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Frozoni, Marcos Roberto dos Santos 1969. "Efeito do fluor na organização supramolecular da matriz organica do esmalte dentario em camundongos." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290014.
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Orientador: Sergio Roberto Peres LineDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: A biossíntese do esmalte dentário inicia-se pela secreção, processamento proteolítico e auto-agregação de uma complexa mistura de proteínas, sintetizadas pelos ameloblastos, conhecida como matriz orgânica do esmalte. A formação desta matriz ocorre em três estágios: secreção (inicial), transição e maturação e parece ser fundamental para o controle da orientação e morfologia dos cristais de hidroxiapatita, que constituem a fase mineral do esmalte em desenvolvimento. No estágio de secreção da amelogênese, a matriz orgânica do esmalte apresenta uma organização supramolecular birrefringente, dessa forma, a referida matriz pode ser observada e quantificada por meio de microscopia de luz polarizada. Alterações genéticas e ambientais podem induzir a distúrbios na organização molecular da matriz orgânica extracellular do esmalte (MOECE) dentário no estágio secretório, gerando modificações em sua birrefringência, tais distúrbios podem contribuir para alterações na estrutura do esmalte maduro. Altos níveis de ingestão de flúor causam mudanças na estrutura e concentração das proteínas da matriz orgânica do esmalte, induzindo a falhas na mineralização e formação desorganizada dos cristais do esmalte. Estas alterações caracterizam a fluorose de esmalte e incluem aumento da porosidade, redução do conteúdo mineral e diminuição da microdureza do esmalte maduro. O objetivo deste estudo foi analisar os efeitos do flúor sobre a birrefringência da MOECE no estágio secretório. Quinze camundongos da linhagem A/J foram divididos em 3 grupos e submetidos a um tratamento de 30 dias com dieta exclusiva de ração e água deionizada ad libitum. A água ingerida continha 0, 25, e 50 ppm de flúor (NaF) nos grupos A/J-Controle, A/J-Flúor 25 ppm e A/J-Flúor 50 ppm, respectivamente. Os mesmos procedimentos foram aplicados a quinze camundongos da linhagem NOD (Non Obese Diabetic), caracterizando os grupos NOD-Controle, NOD-Flúor 25 ppm e NOD-Flúor 50 ppm. Após o período acima mencionado, todos os animais foram perfundidos com uma mistura de paraformaldeído 2% com glutaral deído 0,5% em tampão fosfato 0,2 M e suas hemimaxilas foram extraídas e mantidas na mesma solução fixadora por 16h, as amostras foram então descalcificadas em mistura de ácido nítrico 5% com formaldeído 4 % por 6 h sob agitação. Após desidratação e inclusão em parafina, obtive-se cortes longitudinais de 5µm de espessura que foram desparafinizados, hidratados, montados em solução aquosa de glicerina 80% e analisados em microscopia de luz polarizada. Realizou-se a análise da matriz orgânica dos incisivos superiores de modo a se determinar o retardo óptico em nanômetros (nm) na área de maior birrefringência no estágio de secreção da amelogênese. Os valores de retardo ótico foram submetidos à análise estatística (Kruskal-Wallis) e os grupos A/J e NOD foram comparados separadamente. Observou-se um aumento, estatisticamente significante, dos valores de retardo ótico nos grupos A/J-Flúor 25 ppm e A/J-Flúor 50 ppm, quando comparados ao grupo A/J-Controle (p<0,01). O mesmo aconteceu com os grupos NOD-Flúor 25 ppm e NOD-Flúor 50 ppm que mostraram aumento, estatisticamente significante, dos valores de retardo ótico quando comparados ao grupo NOD-Controle (p<0,01). Os grupos A/J-Flúor apresentaram valores semelhantes (p>0,05) o que também ocorreu com os grupos NOD-Flúor. Os resultados do presente estudo mostram que o flúor induz a um aumento da birrefringência da MOECE no estágio de secreção, podendo estar associado ao mecanismo de desenvolvimento da fluorose de esmalte
Abstract: Dental enamel biosynthesis begins with secretion, proteolytic processing and self-assembly of a highly complex mixture of proteins, synthesised by ameloblast, which is known as the enamel organic matrix. This matrix formation occurs at three stages: secretion (initial), transition and maturation and seems to be essential for controlling orientation and morphology of the hydroxyapatite crystals that comprise mineral phase of developing enamel. In the secretory stage of amelogenesis, the enamel organic matrix presents a birefringent supramolecular organization. Therefore, it can be observed and quantified by polarizing microscopy. Genetic and environmental alterations may induce disturbances in the molecular organization of the secretory-stage enamel organic extracellular matrix (EOECM), producing birefringence changes, these disturbances may contribute to mature enamel alterations. High levels of ingested fluoride cause modifications in the structure and concentration of proteins of the enamel organic matrix inducing failures in the mineralization and disorganized enamel crystals formation. These alterations characterize enamel fluorosis, include increased porosity, mineral content reduction and diminished mature enamel micro hardness. The aim of the present study was to analyse the effects of fluoride on the birefringence of secretory stage EOECM. Fifteen A/J inbred mice strain were divided into 3 groups and submitted to a treatment during 30 days with exclusive diet of food and deionized water ad libitum. The ingested water contained 0, 25 and 50 ppm fluoride (NaF) in the groups A/J Control, A/J 25 ppm fluoride and A/J 50 ppm fluoride, respectively. The same procedures were applied to fifteen NOD (Non Obese Diabetic) mice, which formed the groups NOD Control, NOD 25 ppm fluoride and NOD 50 ppm fluoride. After the abovementioned period, all the animals were perfused with 2% paraformaldehyde, 0.5% glutaraldehyde in 0.2 M phosphate buffered solution. Its hemimaxillae were then extracted and maintained in the same fixative solution for 16 h, the samples were decalcified under stirring in 5% nitric acid, 4% formaldehyde for 6 h. After dehydration and embedded in paraffin, longitudinal 5-µm-thick sections were obtained and deparaffined, hydrated and mounted with aqueous 80% glycerine as imbibing medium and analyzed with polarizing microscopy. Optical retardation (nm) of the area that showed the highest birefringence brightness in the EOECM of upper incisors was determined. Optical retardation values were submitted to statistical analysis (Kruskal-Wallis) and A/J and NOD groups were separately compared. An statistically significant increase in optical retardations values was observed in A/J 25 ppm Fluoride and A/J 50 ppm Fluoride, when compared to A/J Control group (p<0.01). The same happened with NOD 25 ppm Fluoride and NOD 50 ppm Fluoride groups which exhibited statistically significant increase in optical retardations values when compared to NOD Control group (p<0.01). A/J Fluoride groups presented similar optical retardation values (p>0.05) which occurred with NOD fluoride groups. The results presented here show the fluoride induces an increase in the birefringence of secretory stage EOECM, which may be associated with enamel fluorosis development. Key words: Enamel, Amelogenesis, Enamel Organic Matrix, Birefringence, Fluoride
Mestrado
Histologia e Embriologia
Mestre em Biologia Buco-Dental
30
Wan, Qiujie. "Dual wavelength polarimetry for monitoring glucose in the presence of varying birefringence." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3335.
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In a continuing effort to develop a noninvasive means of monitoring glucose levels
using the aqueous humor of the eye, a dual wavelength system has been developed in
order to show that varying birefringence, similar to what is seen with a moving cornea,
can be compensated. In this paper a dual wavelength, closed-loop, system was designed
and a model was developed to extract the glucose concentration information. The system
and model were tested using various concentrations of glucose in a birefringent test cell
subject to motion artifact. The results show that for a static, non-moving sample, glucose
can be predicted to within 10 mg/dl for the entire physiologic range (0-600mg/dl) for
either laser wavelength (523nm or 635nm). In the presence of moving birefringence,
each individual wavelength produced standard errors on the order of a few thousand
mg/dL. However, when the two wavelengths are combined into the developed model,
this error is less than 20mg/dL. The approach shows that multiple wavelengths can be
used to drastically reduce the error in the presence of a moving birefringent sample. This
research also shows promising preliminary results that the error is less than 25mg/dl in
presence of a motion induced cornea birefringence artifact in NZW rabbits eyes.
31
Haghtalab, Ali. "The use of flow birefringence to study nonlinear viscoelasticity in molten polymers /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65930.
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Almayahi, Ali Z. "SHEAR-WAVE IMAGING AND BIREFRINGENCE IN A COMPLEX NEAR-SURFACE GEOLOGICAL ENVIRONMENT." UKnowledge, 2013. http://uknowledge.uky.edu/ees_etds/12.
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Multiple geophysical and geological data sets were compiled, reprocessed, and interpreted using state-of-the-art signal processing and modeling algorithms to characterize the complex post-Paleozoic geology that overlies the southwestern projection of the Fluorspar Area Fault Complex (FAFC) in western Kentucky. Specific data included 21.5 km of SH-wave seismic reflection, 1.5 km of P-wave seismic reflection, 2 km of electrical resistivity, vertical seismic profiles, Vp and Vs sonic-suspension logs, and 930 lithologic borehole logs. The resultant model indicates three general northeast–southwest-oriented fault zones pass through the study area as southwestern extensions of parts of the FAFC. These fault zones form two significant subparallel grabens with ancillary substructures. The geometry of the interpreted fault zones indicates that they have undergone episodic tectonic deformation since their first formation. Evidence of thickening and steeply dipping reflectors within Tertiary and Quaternary sediment in the downthrown blocks indicate syndepositional movement. Subtle thickening and lack of steeply dipping intraformational reflectors in the Cretaceous suggest a more quiescent period, with sediment deposition unconformably draping and filling the earlier Paleozoic structural surface. There is also evidence that the Tertiary and early Quaternary reactivation was associated with an extensional to compressional regional stress reversal, as manifested by the antiformal folds seen in the hanging wall reflectors and the potential small-amplitude force folds in the Quaternary alluvium, as well as a clear displacement inversion along the Metropolis-loess seismic horizon in two high-resolution reflection images.
A surface shear-wave splitting experiment proved to be an efficient and effective tool for characterizing shallow subsurface azimuthally anisotropic geologic inclusions in low-impedance water-saturated sediment environments. The measured azimuthal anisotropy across a well-constrained N60ºE-striking fault exhibited a natural coordinate system that had a fast direction coincident with the fault strike and an orthogonal slow direction. This is also one indicator that faults inactive during significant geologic intervals (i.e., Holocene) do not "heal". Integrated shear-wave velocity models and electrical resistivity tomography profiles across the fault zones exhibit lower shear-wave velocities and resistivities within the deformation zones compared with values outside the boundaries. This is additional evidence that the deformed sediment does not reconsolidate or heal, but that the sediment particle configuration remains more loosely packed, providing an increase in the overall porosity (i.e., hydraulic conductivity). This can wholly or in large part explain the anomalous contaminant plume migration path that is coincident with the deformed zones of the regional gravel groundwater aquifer.
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NAVEZ, PATRICK. "Relaxation dielectrique et birefringence electrique de rotateurs lineaires rigides en milieux thermalises." Paris 11, 1995. http://www.theses.fr/1995PA112538.
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L'etude des proprietes dielectriques et de birefringence engendrees par le mouvement rotationnel des molecules dans les fluides presente des difficultes theoriques fondamentales. La principale reside dans le fait que differents aspects de la relation entre les modeles phenomenologiques utilises couramment et la dynamique microscopique ne sont pas bien compris. En vue de clarifier cette situation nous avons considere deux modeles hamiltoniens: 1) le modele du rotor polarise et fixe en son centre, interagissant avec un bain d'oscillateurs harmoniques. 2) le modele du polymere lineaire rigide, polarise et dilue dans un fluide monoatomique non polaire. Le travail original s'articule comme suit: a) partant des principes de base de la mecanique statistique, nous avons etabli des equations maitresses pour la fonction de distribution reduite associee au mouvement rotationnel. B) a partir de ces equations maitresses, nous avons retrouve des modeles phenomenologiques connus. Trois modeles-types se presentent dans le cadre du travail. 1) le modele brownien. 2) le modele quantique de faible couplage. 3) le modele de grandes collisions. C) nous avons calcule la susceptibilite electrique non lineaire et la fonction d'effet kerr en fonction d'un champ electrique dependant du temps
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Lu, Bin. "Characterization of drag-reducing surfactant systems by rheology and flow birefringence measurements /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487945015617324.
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Yang, Shun-Hui. "Giant birefringence silicon nanophotonic multi-slot waveguides for optical delay line applications." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3329926.
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Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed November 14, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 96-103).
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Riley, Scott Allen. "Magnetic resonance and optical birefringence studies of electrically and magnetically aligned molecules /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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Dumitru, Alina Gabriela. "Quantum theory of light scattering at finite temperature." Thesis, Nottingham Trent University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241832.
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Ellison, John G. "A polarimetric optical time domain reflectometer." Thesis, University of Essex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285848.
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Montarou, Carole C. "Low-level birefringence methods applied to the characterization of optical fibers and interconnects." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6993.
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Birefringence measurements are of great importance in a plethora of applications spanning from biology to optical communications. Birefringence measurements of nerve-fiber layers have emerged as an important diagnostic technique for early detection of glaucoma. Stress-induced birefringence in optical devices affects their performances by causing Polarization-Mode Dispersion (PMD) and Polarization-Dependent Loss (PDL). Stress-relaxation constitutes a key phenomenon governing the fabrication of some optical devices such as Long-Period Fiber Gratings (LPFGs). This drives the need to develop accurate optical instrumentation techniques to evaluate form and stress-induced birefringence.
This thesis deals with the development of new high-accuracy techniques for the characterization of stress-induced birefringence in optical devices. The new Two-Waveplate Compensator (TWC) technique is presented for single-point retardation measurements. It is extensively compared theoretically and experimentally to existing techniques including the Snarmont and Brace-Khler techniques. The Phase-Stepping Two-Waveplate Retarder (PSTWR) is also presented for high-accuracy measurements of retardation magnitude and orientation. The Colorimetry-Based Retardation Method (CBRM) is presented to measure retardation using white-light interference colors. The technique is implemented using a polarization microscope and a spectrophotometer.
The TWC and the Brace-Khler methods are implemented for full-field retardation measurements using a polarization microscope. Their accuracies are quantified over the entire field-of-view for small retardations. They are applied to the stress-induced birefringence imaging of LPFGs and polymer pillar waveguides. The TWC technique achieves an accuracy of 0.06 nm and a sensitivity of 0.07 nm. The Brace- Khler technique achieves an accuracy of 0.04 nm and a sensitivity of 0.09 nm. The spatial resolution of both techniques is 0.45 and #61549;m.
A Fourier-based algorithm is presented to compute the inverse Abel transform relating the retardation to the axial residual stress profile in optical fibers. It is used to calculate the residual stress profiles of single-mode fibers from full-field retardation measurements with the TWC and Brace- Khler techniques. The stress profiles computed in this work are in very good agreement with previously reported results in the literature. The TWC technique produces the most accurate stress measurements. The TWC technique is used to investigate the stress-relaxation phenomena in LPFGs fabricated using CO2 laser irradiations.
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Palmer, Benjamin Alexander. "Structural properties, X-ray birefringence and crystal growth of solid organic inclusion compounds." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/37422/.
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This thesis presents several new insights into the behaviour and properties of solid organic inclusion compounds and explores some of the potential applications of these properties. The thesis considers the structural properties, X-ray birefringence and crystal growth of urea and thiourea inclusion compounds. Chapter 1 provides an introduction to organic solid inclusion compounds, surveying the physico-chemical properties and applications of urea and thiourea inclusion compounds. In Chapter 2, the basic theory of the experimental techniques utilized in this thesis is introduced. These techniques include single-crystal and powder X-ray diffraction, Raman microspectrometry and differential scanning calorimetry. Chapter 3 presents a novel strategy for retrospectively mapping the growth history of a crystal. The new experimental strategy allows insights to be gained on the evolution of crystal growth processes by analysis of crystals recovered at the end of crystallization. The feasibility of the strategy is demonstrated by considering the crystal growth of a urea inclusion compound containing a binary mixture of guest molecules. After the crystal has finished growing, the composition of the crystal is determined using confocal Raman microspectrometry, and is interpreted to yield insights into the growth history of the crystal. In Chapter 4, new insights into the phase transition behaviour of thiourea inclusion compounds are established. The structural properties of the bromocyclohexane/thiourea inclusion compound are determined using both single-crystal and powder X-ray diffraction over a range of temperatures above and below a first-order phase transition. The results demonstrate marked contrasts to the phase transition behaviour in the prototypical cyclohexane/thiourea inclusion compound, demonstrating that relatively small changes in molecular geometry (in this case bromine substitution) can have a profound influence on the structural properties of the low-temperature phase in such materials. This observation reflects the fine energetic balances that pertain in such materials and the role of small and subtle changes in intermolecular interactions involving the host and guest components. Chapter 5 reports the first definitive demonstration of the phenomenon of X-ray birefringence, reporting a material that exhibits essentially ideal birefringence behaviour at X-ray energies near the Br K-edge. The designed material, the 1-bromoadamantane/thiourea inclusion compound gives experimental behaviour in excellent agreement with theoretical predictions for the dependence of transmitted X-ray intensity on both X-ray energy and crystal orientation. The results vindicate the potential to exploit this phenomenon to establish a detailed understanding of molecular polarization, particularly as an experimental strategy to determine the orientational distributions of specific bonds in solids, for example, in the case of partially ordered materials or materials that undergo order-disorder phase transitions. Building upon the fundamentally important observations of Chapter 5, Chapter 6 demonstrates that measurements of X-ray birefringence can be used to characterise changes in molecular polarization and bond orientation in an anisotropic material. For the bromocyclohexane/thiourea inclusion compound, measurements of X-ray birefringence are used to determine the changes in the orientational distribution of the C–Br bonds of the guest molecules, associated with an order-disorder phase transition in this material. Best-fits to simulated data based on a structural model were performed, allowing quantitative structural information on the guest molecules to be established. The structural properties determined from X-ray birefringence correlate exquisitely with those obtained independently from diffraction data, demonstrating the validity of the structural model and the reliability of this novel experimental technique. These observations represent the basis of a new technique for determining information on the structural properties of materials, where diffraction methods may be unsuitable. The technique has huge potential to be utilised in the exploration and discovery of new materials and in principle could be applied to any anisotropic system. In Chapter 7, the first example of an incommensurate thiourea inclusion compound is reported. X-ray diffraction studies reveal that the tunnel inclusion compound formed between 1-tert-butyl-4-iodobenzene and thiourea has an incommensurate relationship between the periodicities of the host and guest substructures along the tunnel axis, representing the first reported case of an incommensurate thiourea inclusion compound. Finally in Chapter 8, some general conclusions and outlooks for the field are stated. This chapter conveys some of the overarching concepts and questions which motivated the diverse studies presented in this thesis and also expresses some thoughts on the future outlook for the field.
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Burnett, James Gordon. "Control of dispersion and birefringence in an optical single-mode fibre stellar interferometer." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/546.
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Folkes, Duncan Edward. "Myosin head orientation in demembranated muscle fibres measured with a birefringence-interference microscope." Thesis, King's College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243967.
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Edwards-Gau, Gregory R. "X-ray Birefringence Imaging and other fundamental aspects of solid organic inclusion compounds." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/75370/.
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This thesis presents new experimental techniques and utilizes these strategies in the analysis of solid organic inclusion compounds. This thesis also reports the production of a new series of co-crystals and examines their crystal structures. Chapter 1 acts as an introduction to the materials studied in this research. It explains the properties of inclusion compounds and lists the chemical materials used for these experiments. Chapter 2 explains the experimental techniques used in this research. Specifically it explains X-ray diffraction, X-ray birefringence and in-situ solid-state NMR. Chapter 3 presents a new technique for spatially resolved mapping of specific bond orientations in anisotropic solid materials using wide beam linearly polarized X-rays and an area detector. Earlier work with a focussed beam and a point detector showed the sensitivity of X-ray Birefringence to the orientation of specific energy-matching bonds inside a material, but these experiments only probed a small section of the crystal. Our wide beam imaging technique (X-ray Birefringence Imaging) shows similar sensitivity but allows us to investigate the full crystal simultaneously, which allows us to identify different domains within a single crystal. We apply this technique to a model material (1 bromocyclohexane/thiourea) which undergoes a low temperature phase transition and serves to demonstrate the usefulness of imaging techniques - in the high temperature phase the relevant C−Br bonds are isotropically disordered and no birefringence is observed, in the low temperature phase the relevant C−Br bonds are ordered but there are three possible orientations for the bromocyclohexane molecule so different regions of the crystal exhibit different birefringent signal. This behaviour is very clear on an imaging technique, but can appear highly confusing when using point-detector techniques. Chapter 4 utilizes X-ray Birefringence Imaging to investigate the dynamic rotational properties of guest molecules in a different set of solid organic inclusion compounds. By studying the known structures of 1,10-dibromodecane/urea and 1,8-dibromooctance/urea we have determined that XBI is a time-averaged and space-averaged technique. Additionally this chapter utilizes a Ge(555) analyzer instead of the Si(555) analyzer, which results in better spatial resolution and a different beam shape on the final images. Chapter 5 utilizes solid-state in-situ NMR to monitor crystallization processes as they occur and gain insight on competitive uptake of different guest molecules within the inclusion compound. These experiments use alkane and α,ω-dibromoalkane guest molecules inside urea inclusion compounds where the urea host structure (created in-situ) acts like a one-dimensional tunnel confining the guest. Every position within the urea tunnel is equivalent (a property of the incommensurate structure) which serves to simply the solid-state NMR spectra and means that for a given atom at the end of an alkane chain the only difference in NMR site comes from the neighbour molecule along the tunnel. This means in the solid phase we can observe peak splitting on certain atoms based on neighbour environment (e.g. the -CH3 in undecane will give a slightly different chemical shift if the neighbouring guest molecule is another undecane compared to if the neighbouring guest molecule is 1,8-dibromooctane) which in turn allows us to extract some information about the ordering within the inclusion compound. In these experiments we can also clearly distinguish between the same molecules in different phases, so as crystallization occurs we observe the loss of solution signal alongside the gain of solid signal. Additionally these experiments show no evidence of any intermediate structures or transition states. Chapter 6 describes a new set of organic co-crystals formed by reacting thiourea with α,ω-diiodoalkane chains and examines the crystal structures of these materials. Chapter 7 details further work and potential applications of this research. Digital data includes animated videos of the X-ray birefringence imaging data obtained in Chapter 3 and CIF files of the structures determined in Chapter 6.
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Montarou, Carole Claudette. "Low-level birefringence methods applied to the characterization of optical fibers and interconnects." Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04072005-112316/unrestricted/montarou%5Fcarole%5Fc%5F200505%5Fphd.pdf.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005.Phillip First, Committee Member ; Gee-Kung Chang, Committee Member ; John Buck, Committee Member ; Glenn Smith, Committee Member ; Thomas Gaylord, Committee Chair. Includes bibliographical references.
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Kasaragod, Deepa Kamath. "Enhanced contrast in OCT imaging of tissues using birefringence, scattering and speckle signatures." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/2239/.
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The three objectives listed here are the main aim presented in each of the chapters of this thesis. The research work carried out with respect to fulfilling these objectives is one step closer towards extending the possibility of non-invasive imaging modality of OCT and PS-OCT in the field of orthopaedics and tissue engineering. - Non-invasive technique to understand the depth-dependent 3D collagen framework of articular cartilage. - Non-invasive technique to discriminate between different types of connective tissue based on angle-resolved backscattering profiles - Computer based tissue discrimination based on the speckle textural analysis of the OCT images obtained Articular cartilage was imaged using two different schemes of implementation of PS-OCT: time domain PS-OCT and swept source based continuous polarisation modulation PS-OCT system. Detailed analysis is presented for time-domain PS-OCT data obtained from bovine articular cartilage sample over multi-angle measurements and a comparative study of the phase retardance profiles obtained from experimental data is done with those obtained from a layered model of articular cartilage using extended Jones matrix calculus. This includes a noise model chosen for the time domain PS-OCT system to add noise bias to the simulated results. Optimiser algorithms are developed based on this model. This study shows the possibility of using PS-OCT imaging towards non-invasive technique to study the microstructure of articular cartilage. The technique of multi-angle imaging in PS-OCT has also been used in the study of angleresolved backscattering, with the information regarding the reflectivity profiles as obtained from a normal OCT system used for the study. The two connective tissues under study are bovine tendon sample and bovine articular cartilage sample. Articular cartilage is predominantly made of Type II collagen fibrils which are finer and more uniform in nature compared to that in tendon tissue which is predominantly Type I collagen fibrils of larger diameters and coarser packing arrangements. Single scattering model of OCT is used to obtain the angle-resolved backscattering curves and Rayleigh Gans scattering approximation based simulation is carried out to elucidate and understand the results obtained. Speckle texture analysis is carried out to extract sub-resolution based information from OCT towards computer-based classification of different types of OCT images. This has been carried out first on tissue phantoms made of agar-intralipid solutions of different concentrations. Statistical features are extracted and grouped into 3-set features to obtain scatter-plots and receiver operating characteristic curves that determine the correctness of the classification obtained of a particular group of OCT images from the total sample set. With initial success from tissue phantom based speckle textural analysis, this has been extended to study the data classification ability of normal skin from tissue engineered skin with different types of melanoma cell-lines invasion as well as discriminate different types of melanoma invasion of tissue-engineered skin from each other.
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Tharp, Jeffrey Scott. "DESIGN AND DEMONSTRATION OF MEANDERLINE RETARDERS AT INFRARED FREQUENCIES." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2813.
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Meanderline structures are widely used as engineered birefringent materials for waveplates and retarders at radiofrequencies, and have been previously demonstrated at frequencies up to 90 GHz in the millimeter-wave band. In this dissertation, we present results related to the modeling, fabrication, and experimental characterization of meanderlines across the range from 30 to 100 THz, in the long-wave and mid-wave infrared bands. Specific issues addressed in these new designs include spectral dispersion and angular dependence of the retardance, as well as axial ratio and throughput. The impact resulting from the infrared properties of the metals and dielectrics is explicitly included throughout. Several novel applications are identified, including integrated circular polarizers, reflective waveplates, and large-area polarization tags.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Moreira, Danna Mota. "Analise por microscopia de polarização e microscopia eletronica de varredura da estrutura dentinaria de dentes bovinos frente a diferentes substancias quimicas auxiliares de uso endodontico." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289846.
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Orientador: Alexandre Augusto ZaiaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo desse trabalho foi avaliar a ocorrência de alterações na estrutura e organização do colágeno presente na matriz orgânica da parede dentinária do canal radicular de incisivos bovinos bem como, avaliar a topografia da matriz inorgânica desta estrutura após irrigação com hipoclorito de sódio 5,25%, EDTA 17% e clorexidina gel 2%. Foram utilizados 60 dentes bovinos divididos aleatoriamente em seis grupos com 10 dentes cada: G1 - Hipoclorito de sódio (NaOCl) 5,25% e EDTA 17%; G2 - Clorexidina gel 2%; G3 - NaOCl 5,25%; G4 - EDTA 17%; G5 - Clorexidina gel 2% e EDTA 17%; G6 - Solução de cloreto de sódio 0,9% (Controle). Uma análise paralela foi realizada em 10 dentes onde nenhum tipo de procedimento foi realizado, sendo possível a obtenção dos parâmetros da birrefringência característica de incisivos bovinos sem instrumentação. As amostras experimentais foram submetidas à instrumentação e irrigação com as diferentes substâncias químicas auxiliares e em seguida, segmentadas em dois fragmentos. Um fragmento foi processado histologicamente utilizando o corante pricrosirius e em seguida, seu retardo óptico foi mensurado por meio de microscopia de polarização. O outro segmento foi preparado e avaliado por meio de microscopia eletrônica de varredura. Os resultados das mensurações dos retardos ópticos foram submetidos à análise estatística por meio do teste de Dunnet. Os resultados demonstraram que os grupos tratados com a clorexidina gel 2% e EDTA 17%, associados ou não, não obtiveram diferença estatisticamente significante em relação ao grupo controle. Nos grupos tratados com NaOCl 5,25%, associado ou não ao EDTA 17%, as médias dos retardos ópticos foram estatisticamente diferentes ao grupo controle. Concluindo que o NaOCl 5,25% provoca alterações na organização macromolecular do colágeno presente na matriz orgânica da dentina radicular de dentes bovinos. A análise realizada por meio da MEV demonstrou alterações estruturais na matriz inorgânica em todos os grupos em que o EDTA 17% foi utilizado
Abstract: The aim of this study was to evaluate the change in collagen structure and organization present in the organic matrix of the dentine wall of the root canals of bovine inferior incisors as well as the topography of the inorganic matrix after irrigation with 5.25% sodium hypochlorite, 17% EDTA and 2% chlorexidine gel. Sixty bovine incisors were randomly divided into six groups of 10: G1 - 5.25% Sodium Hypochlorite (NaOCl) and 17% EDTA; G2 - 2% Chlorexidine gel; G3 - 5.25% NaOCl; G4 - 17% EDTA; G5 - 2% Chlorexidine gel and 17% EDTA; G6 (Control) - 0.9% Sodium chloride. A parallel analysis was performed with 10 teeth which had not been submitted to any treatment. Hence, it was possible to obtain parameters for the birefringence characteristic of non-instrumented inferior bovine incisors. Experimental samples were submitted to instrumentation and irrigation with different auxiliary chemical substances and then segmented in two. One fragment was histologically processed using picrosirius pigment. Its optical retardations were measured through polarization microscopy. The second fragment was prepared to be evaluated through scanning electron microscopy. The optic retardation measurement data were submitted to statistical analysis using Dunnet?s test. Results revealed that the groups that associated or not 2% chlorexidine gel and 17% EDTA were not statistically different in relation to the control group. For the groups which 5.25% NaOCl was used, associated or not to 17% EDTA, the average optic retardations were statistically different to the control group. Therefore, 5.25% sodium hypochlorite proved to cause alterations to the molecular organization of collagen present in the organic matrix of root dentine of bovine teeth. Scanning electron microscopy showed structural alterations of the inorganic matrix of all groups tested with 17% EDTA
Mestrado
Endodontia
Mestre em Clínica Odontológica
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Moreira, Danna Mota. "Influência de substâncias químicas auxiliares de uso endodôntico e agentes redutores nas propriedades biomecânicas da dentina radicular." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289790.
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Orientador: Alexandre Augusto ZaiaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Dentre os protocolos de irrigação mais utilizados mundialmente, a associação do hipoclorito de sódio (NaOCl) e o EDTA merece destaque. Entretanto, estes agentes químicos podem causar efeitos deletérios nas propriedades químicas e físicas da dentina, além da ação oxidativa do NaOCl interferir no comportamento de materiais restauradores. O uso de agentes redutores tem demonstrado minimizar os efeitos deletérios do NaOCl previamente a procedimentos restauradores. No primeiro estudo que compõe esta tese teve-se como objetivo avaliar os efeitos do ácido ascórbico 10% e/ou ascorbato de sódio 10% após a irrigação com NaOCl 5,25%, EDTA 17% ou cloreto de sódio 0,9% no colágeno presente na matriz orgânica da parede dentinária do canal radicular de incisivos bovinos. Foram utilizados oitenta incisivos bovinos aleatoriamente divididos em oito grupos (n=10): G1(Controle): cloreto de sódio 0,9%; G2: NaOCl 5,25% + EDTA 17%; G3: NaOCl 5,25% + EDTA 17% + ácido ascórbico 10%; G4: NaOCl 5,25% + EDTA 17% + ascorbato de sódio 10%; G5: NaOCl 5,25%; G6: EDTA 17%; G7: ácido ascórbico 10%; G8: ascorbato de sódio 10%. Os espécimes foram submetidos à instrumentação e irrigação com as diferentes substâncias químicas auxiliares e em seguida submetidos ao processamento histológico para análise em microscopia de polarização. Os grupos que demonstraram alteração no padrão de birrefringência foram submetidos à análise de absorbância para a confirmação da perda de proteína. Foi possível concluir que o uso do ácido ascórbico 10% e/ou ascorbato de sódio 10% conseguiu restabelecer os valores de retardo óptico antes diminuídos pelo uso de NaOCl 5,25%, associado ou não ao EDTA 17%. Já no segundo estudo, este teve como objetivo avaliar os efeitos do ácido ascórbico 10% e/ou ascorbato de sódio 10% após a irrigação com NaOCl 5,25%, EDTA 17% ou cloreto de sódio 0,9% na microdureza Knoop e resistência flexural da dentina radicular bovina. A distribuição dos grupos foi feita de forma similar ao primeiro estudo. Foram utilizados 80 dentes bovinos para o teste de microdureza Knoop e 120 barras de dentina para o ensaio de flexão de 3-pontos. O NaOCl 5,25% reduziu de forma significativa os valores de microdureza Knoop, chegando a afetar a dureza mesmo em grandes profundidades na dentina radicular bovina. A aplicação de ascorbato de sódio conseguiu revertes os valores previamente reduzidos de microdureza. Ficou comprovado que o NaOCl 5,25% afeta de forma negativa a resistência flexural, mas ao se fazer uso do ácido ascórbico após o protocolo de irrigação com NaOCl e EDTA, os valores de resistência flexural foram restabelecidos, chegando mesmo a equiparar-se ao grupo controle
Abstract: Among the auxiliary chemical substances used in Endodontics during chemical-mechanical preparation, sodium hypochlorite (NaOCl) and EDTA have been the most widely recommended. However, irrigant solutions used in endodontic therapy might yield changes in the chemical and physical properties of dentin. Besides, these reagents compromised the bond strengths of some adhesives on root dentin. The aim of the first study was to evaluate the effect of 10% acid ascorbic or 10% sodium ascorbate on organic matrix collagen of bovine dentin root canal walls after irrigation with 5.25% sodium hypochlorite, 17% EDTA or 0.9% sodium chloride. Eighty bovine incisors were randomly divided into eight groups (n=10) according to: G1(Control): 0.9% Sodium Chloride; G2: 5.25% NaOCl + 17% EDTA; G3: 5.25% NaOCl + 17% EDTA + 10% ascorbic acid; G4: 5,25% NaOCl + 17% EDTA + 10% sodium ascorbate; G5: 5.25% NaOCl; G6: 17% EDTA; G7: 10% ascorbic acid; G8: 10% sodium ascorbate. Teeth were chemomechanically prepared and submitted to histological processing to be analyzed under polarized light microscopy. Absorbance assay was also performed to confirm the loss of collagen. It is possible to conclude that groups treated with 5.25% NaOCl (G2 and G5) presented a significantly different birefringence pattern compared with the control group (p<0.05).The birefringence values reduced could be reversed by the application of either 10% ascorbic acid or 10% sodium ascorbate after 5.25% NaOCl and 17% EDTA irrigation. The absorbance assay of G2 and G5 confirmed the loss of collagen (p<0.05). The second study aimed to evaluate the effect of 10% ascorbic acid or 10% sodium ascorbate application after 5.25% NaOCl, 17% EDTA or 0.9% sodium chloride irrigation in the Knoop microhardness and flexural strength on root dentin. Eighty bovine incisors were randomly divided into eight groups (n=10): G1 (Control): 0.9% Sodium Chloride; G2: 5.25% NaOCl + 17% EDTA; G3: 5.25% NaOCl + 17% EDTA + 10% ascorbic acid; G4: 5.25% NaOCl + 17% EDTA + 10% sodium ascorbate; G5: 5.25% NaOCl; G6: 17% EDTA; G7: 10% ascorbic acid; G8: 10% sodium ascorbate. Teeth were chemomechanically prepared and submitted to Knoop microhardness. Standardized plano-parallel dentin bars were prepared and randomly divided into the same eight groups (n=15) cited above. The dentin bars were then loaded to failure in a three-point bend test. Root canal irrigation with 5.25% NaOCl reduced the microhardness of dentin in all distances tested. The microhardness values increased in all distances when sodium ascorbate was used after 5.25% NaOCl and 17% EDTA irrigation. By exposing the dentin bars to 5.25% NaOCl, whether it was associated or not to 17% EDTA, the flexural strength decreased. However, values increased when 10% ascorbic acid or 10% sodium ascorbate were used after 5.25% NaOCl and 17% EDTA irrigation
Doutorado
Endodontia
Doutor em Clínica Odontológica
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Stoffel, Diane. "Caractérisation du matériau Nd : Lu : CaF2 pour l'amplification laser à 1053 nm." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0039/document.
Full textAbstract:
Le laser Mégajoule, dédié à l’interaction laser-matière pour la physique des hautes énergies est composé de modules pré-amplificateurs (MPA) devant respecter une qualité de faisceau exigeante. Les MPA actuels utilisent des matériaux verre phosphate dopé au Néodyme pour un fonctionnement à 1053 nm. Leur cadence de tir est cependant limitée à 1 tir / 5 min à cause de leur faible conductivité thermique. Il serait intéressant d’augmenter cette cadence pour optimiser le temps alignement des optiques ou réaliser des diagnostics sur l’installation laser. Pour augmenter la cadence de tir des MPA, nous proposons de changer le matériau actuel par du Nd :Lu :CaF2 de conductivité thermique dix fois plus élevée en vue d’atteindre une cadence de répétition de 10 Hz. Dans ce travail de thèse, nous présentons une étude des effets thermomécaniques induits par un pompage diode inhomogène et transverse, de fluence 13 J/cm2. Nous présentons les mesures de biréfringence résolues spatialement avec un montage en polariseur-analyseur croisés. La distribution des contraintes thermomécaniques associées est reconstruite par un modèle de simulation avec le logiciel COMSOL®. Enfin, une étude de l’influence de l’orientation cristalline du Nd :Lu :CaF2 est développée afin d’expliquer la disparité de biréfringence induite mesurée entre les échantillon de Nd :Lu :CaF2Laser facility such as the Megajoule Laser dedicated to laser-matter interaction including inertial fusion need pre-amplifier modules (PAM) which must respect a high beam quality. The current PAM use Phosphate glass doped with Neodymium material to work at 1053 nm with a repetition rate of 1 shot / 5 min limited by a low thermal diffusion. However, it would be interesting to increase the shot rate for alignment or diagnostic purposes. Therefore, we propose to change this amplification material by crystal Nd :Lu :CaF2 with a thermal diffusion ten times higher in view of achieving a repetition rate of 10 Hz. In this PhD work, we report a characterization of the thermal induced effects under a diode inhomogeneous and transverse pump with an energy density of 13 J/cm2. We begin by studying the spatially resolved induced birefringence with a cross polarizer-analyzer setup. We reconstruct the stress pattern of our samples by simulating the global setup with COMSOL® software which includes the thermal and mechanic Multiphysics interaction. This model allows us first to compare with experimental results and then to entirely simulate the mechanical behavior of this new material. A detailed study of the influence of the crystal orientation on the induced birefringence is presented to explain the disparity observed on the different samples Nd :Lu :CaF2 measurements
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Soulages, Johannes Matthieu. "Flow birefringence and velocity measurements for polymer melts in a cross-slot flow channel /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17180.
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