Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Orientador: Rogério Dias / Coorientador: Reginaldo G. C. Lopes / Banca: Nilton José Leite / Banca: Francisco de Assis Costa Souza / Resumo: O Pólipo endometrial é a doença endometrial mais prevalente. Sangramento uterino anormal (SUA) e infertilidade são condições clínicas frequentemente associadas com a presença dessa entidade. O risco de malignização é baixo, mas aumenta em mulheres na pós-menopausa com SUA ou idade superior a 60 anos. O tratamento consiste na exérese através de histeroscopia cirúrgica ambulatorial ou hospitalar. A energia elétrica bipolar é a forma de energia convencionalmente utilizada em ambiente ambulatorial. Como o laser apresenta algumas vantagens sobre a corrente elétrica e o custo das fibras óticas empregadas com o laser diodo é menor, pode-se adicionar uma contribuição ao campo da histeroscopia cirúrgica ambulatorial. O objetivo deste estudo foi descrever as técnicas de polipectomias histeroscópicas com laser diodo sem anestesia, identificar o perfil clínico- epidemiológico das pacientes portadoras de pólipo endometrial para caracterização da amostra estudada, analisar a viabilidade da polipectomia histeroscópica com laser diodo, assim como, a tolerabilidade das pacientes à técnica empregada, e analisar as vantagens e desvantagens da polipectomia ambulatorial com laser diodo. Trata-se de estudo clínico descritivo analítico de avaliação prospectiva com amostra de conveniência, realizada no período de dezembro de 2011 a maio de 2012, de 31 pacientes que foram submetidas à polipectomia histeroscópica ambulatorial sem anestesia com laser diodo à potência de 4W em modo contínuo por contato, após realização de histeroscopia ambulatorial diagnóstica, sendo que 24 tinham diagnóstico histeroscópico de pólipo endometrial único compreendido entre 1cm e 2cm e 7 foram tratadas no mesmo momento da histeroscopia ambulatorial diagnóstica e apresentavam pólipos compreendidos entre 3cm e 5cm de diâmetro. Todas com boa tolerância à dor, quando da realização da histeroscopia diagnóstica ambulatorial ... / Abstract: Endometrial polyp is the most prevalente endometrial disease. Abnormal uterine bleeding and infertility are clinical conditions often associated with the presence of this entity. The risk of malignancy is low, but increases in postmenopausal women with AUB or in women older than 60 years. Treatment consists of surgical excision via outpatient hysteroscopy or inpatient ressectopies . The electricity conventionally used in the outpatient setting is bipolar Twizzle. As the laser has some advantages over the electric current and the cost of fiber optics used with the diode laser is smaller, we think a contribution to the field of surgical outpatient hysteroscopy may be given. The aim of this study was to describe the techniques of outpatient hysteroscopic polypectomy with diode laser without anesthesia, to identify the clinical and epidemiological profile of patients with endometrial polyp to characterize the sample, analyze the feasibility of hysteroscopic polypectomy diode laser and tolerability of patients to the technique and also, analyze the advantages and disadvantages of outpatient hysteroscopic polypectomy with diode laser. Between December 2011 and May 2012 about 31 patients was studied. This study is a descriptive analytic clinical assessment with prospective convenience sample of 31 patients who underwent outpatient hysteroscopic polypectomy without anesthesia with diode laser to the power of 4W in continuous mode by contact, and that, 24 patients have had hysteroscopic diagnosis of endometrial polyp between 1cm and 2cm previously, and 7 women were underwent treated at the same time of diagnostic hysteroscopy and had polyps between 3cm and 5cm in diameter. All women had good pain tolerance when the diagnostic hysteroscopy. We used optical fibers type bare with 1003μ and 603μ in diameter. Two techniques for hysteroscopic polypectomy diode laser were described. We analyzed the clinical-epidemiological ... / Doutor

Laser cleaning is a non contact, highly controllable process for the removal of contaminants from a surface with minimum or no damage to the substrate material. Laser cleaning has been applied mainly on flat and curved surfaces. Little is known on the phenomena and feasibility of laser cleaning of slotted structures. Slots are common structures in engineering, and can be found in many components. In this PhD work, the feasibility of laser cleaning of alpha case on flat titanium alloy surfaces was initially explored, and then an investigation was made on the use of a pulsed laser for the cleaning of micro to macro slots in silicon and metallic materials. The effects of laser processing parameters on the contaminant removal from these slots were experimentally studied. Laser cleaning thresholds and cleanliness was examined. Meanwhile, finite element modelling (FEM) and time domain finite difference modelling techniques were used to simulate the processes involved to aid the understanding of the technique for process optimisation. The experiments were undertaken to verify if such models are able to accurately predict the cleaning thresholds. The surface and sub-surface characteristics before and after laser cleaning were examined using optical microscopy and scanning electron microscopy (SEM). It has been shown that the slot structure and its material properties were not damaged or changed by laser cleaning process. A novel contribution is that surface morphology after the laser ablation could be used as a diagnostic method to indentify the presence of alpha case and measure its thickness due to the specific characteristics of the surface roughness and generated cracks on the ablated surface after laser irradiation. Besides, it has been found that an axial beam which propagates into the narrow slots can successfully clean the tiny particles on the slot sidewalls whose width ranges from 3.5 mm to 13mm. These phenomena had never been reported before.

This diploma thesis deals with the experiment of welding galvanized sheets using fiber laser. The experiment is based on testing of welds lap joints with different gap between the welded parts. Theoretical part of this diploma thesis describes the principles and different types of lasers, laser welding technology, welding defects, galvanizing and inspection of welded joints. In the experimental part of the thesis welding tests and analysis of the results of the experiment have been realised and evaluated.

O objetivo desse estudo foi avaliar in vitro e in situ a efetividade de irradiação dos lasers Er:YAG, Nd:YAG e CO2 no aumento da resistência ácida do esmalte em regiões de sulcos e fissuras. Para o estudo in vitro foram utilizados molares humanos em fragmentos da porção oclusal de 8mmx4mm divididos em 3 grupos de acordo com o tipo de tratamento : Grupo 1 - Er:YAG; Grupo 2 - Nd:YAG; Grupo 3 - CO2 (n=15). O tratamento de superfície foi feito apenas em metade da área do fragmento, sendo que a outra metade foi considerada controle. As áreas expostas ao desafio cariogênico (14mm2) foram submetidas a ciclagens de pH. Para o testede microdureza os espécimes foram seccionados ao meio e a parede da secção é que sofreu o teste, a outra metade foi utilizada para análise em microscopia de luz polarizada para a medição da área da lesão de desmineralização e análise em MEV para verificar as alterações na morfologia do tecido dentário. As análises dos dados de microdureza (HKN) e área das lesões (mm2) foram feitas com o teste de Wilcoxon para a comparação interna de cada grupo com o seu controle e a comparação entre os grupos utilizou ANOVA para as áreas das lesões e Kruskal Wallis para a microdureza (&alpha; = 5%). Foi observada apenas diferença estatística significante para as amostras do grupo irradiado com laser CO2 entre as partes controle e experimental. Os demais grupos não apresentaram diferença estatisticamente significante com sua área controle. Na análise das medidas de lesão foram observadas diferença estatística significante para as amostras do grupo irradiado com os lasers CO2 e Nd:YAG com suas partes controles, sendo as medidas de área de lesão apresentadas pela área irradiada inferiores a área controle. Na análise em MEV o grupo irradiado com laser CO2 mostrou ausência de exposição dos prismas de esmalte e modificação de superfície na área irradiada. Para o estudo in situ foram utilizados molares humanos em fragmentos da porção oclusal de 4mmx4mm tratados com os 3 diferentes tipos de laser: Grupo 1 - controle (sem tratamento); Grupo 2 - Er:YAG; Grupo 3 - Nd:YAG; Grupo 4 - CO2 (n=15). Os espécimes foram adaptados a um dispositivo intrabucal que foi utilizado pelos voluntários durante 14 dias. Para o desafio cariogênico gotejou-se solução de sacarose 20% sobre os espécimes. Assim como no estudo in vitro, foram realizados o teste de microdureza, análise em microscópio de luz polarizada e análise em MEV. Para a análise dos dados de microdureza (HKN) foi utilizada ANOVA e teste de Fisher LSD (&alpha;= 5%). Foi observada diferença estatística significante para as amostras do grupo irradiado com laser CO2 e Nd:YAG, que apresentaram maiores valores de microdureza do que o grupo controle e não foram diferentes estatisticamente entre si. Os valores de microdureza observados em profundidade foram maiores proporcionalmente a distância da superfície, ou seja, 20&micro;m <30&micro;m <40&micro;m <50&micro;m. Na análise em microscopia de luz polarizada a análise foi feita com teste de Wilcoxon e todos os grupos apresentaram semelhança estatística. Considerando os resultados obtidos nos dois estudo pode-se concluir que os lasers CO2 e Nd:YAG foram capazes de promover aumento de resistência ácida no esmalte dental localizado nas superfície de sulcos e fissuras. / The aim of this study was to assess in vitro and in situ the lasers Er:YAG, Nd:YAG e CO2 in preventing enamel demineralization on the pits and fissures surface. For the in vitro study 45 occlusal enamel blocks were randomly divided into 3 groups in according with the treatment: G1 - Er:YAG; G2 - Nd:YAG; G3 - CO2. Treatments were made only on a half of the specimen and the remaining part was considered as a control. The samples were submitted to an in vitro pH cycles. For the microhardness test the specimens were seccioned in the middle and the seccioned wall received the test. The other halves were analyzed using polarized light microscopy for the measurement of the caries-lesion areas and morphological SEM analyses. Wilcoxon test were performed for the statistical analysis of the data obtained from the microhardness test (KHN) and caries-lesion area measurements (mm2) (&alpha;= 5%) when each groups was compared with its control. Variance analysis were performed for the difference in means of microhardness data and Kruskal Wallis test were performed for the difference in means of caries-lesion area measurements (&alpha;= 5%). For the microhardness data the G3 was statically different from its control area and the others groups presented statistical similarity among the experimental and control areas. For the caries-lesion area measurements statistical difference was observed for the groups G2 and G3 presenting smaller caries-lesion area when compared with their respective control areas. In the SEM analysis the G3 showed uniform surface without enamel-prism exposure. For the in situ study 60 occlusal enamel blocks were randomly divided into 4 groups in according with the treatment: G1 - Control (no treatment); G2 - Er:YAG; G3 - Nd:YAG; G4 - CO2 (n=15). The specimens were fixed in intra oral appliances and worn by the volunteers for 14d. Sucrose solution (20%) was applied to each specimen 6 times/d. As the in vitro study the samples were removed, sectioned and examined for microhardness, caries-lesion area measurements on the polarized light microcopy and morphological analyses on SEM. Variance analysis and the Fisher test were performed for the statistical analysis of the data obtained from the microhardness test (KHN) (&alpha;= 5%). The control group was statically different from G3 and G4, which present higher microhardness values and were statistical similar between them. The data of microhardness from the depth of surface were greater in proportion of distance from the surface, as 20&micro;m <30&micro;m <40&micro;m <50&micro;m. Wilcoxon test were performed for the statistical analysis of the data obtained from the caries-lesion area measurements (mm2) (= 5%) and all the groups were statically similar. Considering the results obtained from the both of studies can be concluded that the laser CO2 and Nd:YAG were able to increase the enamel acid resistance on the surface of pits and fissures.

Cette thèse porte sur l'endommagement laser de composants optiques en silice amorphe en régime nanoseconde. Ce matériau diélectrique est l'un des plus couramment utilisés en optique et notamment sur des installations laser de haute énergie telles que le Laser MégaJoule. Afin de garantir le fonctionnement nominal d'une installation, l'endommagement laser des composants optiques doit être compris et maîtrisé. Ce phénomène induit une modification irréversible du matériau modifiant la propagation du faisceau. Dans le régime nanoseconde, l'endommagement laser de la silice est corrélé à la présence de défauts précurseurs qui sont une conséquence de la synthèse et du polissage des composants. L'interaction de ces précurseurs avec le laser va dépendre des caractéristiques de ce dernier. Une première étude est consacrée à la métrologie des impulsions utilisées en laboratoire pour étudier l'endommagement laser. Une seconde étude porte sur les mécanismes d'amorçage des dommages sur la face de sortie des composants optiques faits de silice. Une dernière partie porte sur l'influence de la propagation non linéaire sur l'endommagement surfacique et volumique des composants épais faits de silice. / In this thesis, laser-induced damage phenomenon in fused silica components is investigated in the nanosecond regime. This material is one of the most widely used in optics, particularly on high-energy laser facilities such as the Laser MégaJoule. In order to ensure the nominal operation of this kind of laser facility, laser-induced damage on optical components has to be understood and controlled. This phenomenon consists in an irreversible modification of the material. In the nanosecond regime, laser-induced damage is tightly correlated to the presence of precursor defects which are a consequence of the synthesis and the polishing of the components. The interaction between these precursor defects and the laser pulses strongly depends on the laser characteristics. The first study focuses on the metrology of the laser beam used in laboratory to study laser-induced damage. The second one consists in a parametric study of the initiation mechanism on the rear surface of fused silica components. The last part deals with the influence of nonlinear propagation on laser induced damage on the surface and in the volume of thick fused silica samples.

O objetivo desse estudo foi avaliar in vitro e in situ a efetividade de irradiação dos lasers Er:YAG, Nd:YAG e CO2 no aumento da resistência ácida do esmalte em regiões de sulcos e fissuras. Para o estudo in vitro foram utilizados molares humanos em fragmentos da porção oclusal de 8mmx4mm divididos em 3 grupos de acordo com o tipo de tratamento : Grupo 1 - Er:YAG; Grupo 2 - Nd:YAG; Grupo 3 - CO2 (n=15). O tratamento de superfície foi feito apenas em metade da área do fragmento, sendo que a outra metade foi considerada controle. As áreas expostas ao desafio cariogênico (14mm2) foram submetidas a ciclagens de pH. Para o testede microdureza os espécimes foram seccionados ao meio e a parede da secção é que sofreu o teste, a outra metade foi utilizada para análise em microscopia de luz polarizada para a medição da área da lesão de desmineralização e análise em MEV para verificar as alterações na morfologia do tecido dentário. As análises dos dados de microdureza (HKN) e área das lesões (mm2) foram feitas com o teste de Wilcoxon para a comparação interna de cada grupo com o seu controle e a comparação entre os grupos utilizou ANOVA para as áreas das lesões e Kruskal Wallis para a microdureza (&alpha; = 5%). Foi observada apenas diferença estatística significante para as amostras do grupo irradiado com laser CO2 entre as partes controle e experimental. Os demais grupos não apresentaram diferença estatisticamente significante com sua área controle. Na análise das medidas de lesão foram observadas diferença estatística significante para as amostras do grupo irradiado com os lasers CO2 e Nd:YAG com suas partes controles, sendo as medidas de área de lesão apresentadas pela área irradiada inferiores a área controle. Na análise em MEV o grupo irradiado com laser CO2 mostrou ausência de exposição dos prismas de esmalte e modificação de superfície na área irradiada. Para o estudo in situ foram utilizados molares humanos em fragmentos da porção oclusal de 4mmx4mm tratados com os 3 diferentes tipos de laser: Grupo 1 - controle (sem tratamento); Grupo 2 - Er:YAG; Grupo 3 - Nd:YAG; Grupo 4 - CO2 (n=15). Os espécimes foram adaptados a um dispositivo intrabucal que foi utilizado pelos voluntários durante 14 dias. Para o desafio cariogênico gotejou-se solução de sacarose 20% sobre os espécimes. Assim como no estudo in vitro, foram realizados o teste de microdureza, análise em microscópio de luz polarizada e análise em MEV. Para a análise dos dados de microdureza (HKN) foi utilizada ANOVA e teste de Fisher LSD (&alpha;= 5%). Foi observada diferença estatística significante para as amostras do grupo irradiado com laser CO2 e Nd:YAG, que apresentaram maiores valores de microdureza do que o grupo controle e não foram diferentes estatisticamente entre si. Os valores de microdureza observados em profundidade foram maiores proporcionalmente a distância da superfície, ou seja, 20&micro;m <30&micro;m <40&micro;m <50&micro;m. Na análise em microscopia de luz polarizada a análise foi feita com teste de Wilcoxon e todos os grupos apresentaram semelhança estatística. Considerando os resultados obtidos nos dois estudo pode-se concluir que os lasers CO2 e Nd:YAG foram capazes de promover aumento de resistência ácida no esmalte dental localizado nas superfície de sulcos e fissuras. / The aim of this study was to assess in vitro and in situ the lasers Er:YAG, Nd:YAG e CO2 in preventing enamel demineralization on the pits and fissures surface. For the in vitro study 45 occlusal enamel blocks were randomly divided into 3 groups in according with the treatment: G1 - Er:YAG; G2 - Nd:YAG; G3 - CO2. Treatments were made only on a half of the specimen and the remaining part was considered as a control. The samples were submitted to an in vitro pH cycles. For the microhardness test the specimens were seccioned in the middle and the seccioned wall received the test. The other halves were analyzed using polarized light microscopy for the measurement of the caries-lesion areas and morphological SEM analyses. Wilcoxon test were performed for the statistical analysis of the data obtained from the microhardness test (KHN) and caries-lesion area measurements (mm2) (&alpha;= 5%) when each groups was compared with its control. Variance analysis were performed for the difference in means of microhardness data and Kruskal Wallis test were performed for the difference in means of caries-lesion area measurements (&alpha;= 5%). For the microhardness data the G3 was statically different from its control area and the others groups presented statistical similarity among the experimental and control areas. For the caries-lesion area measurements statistical difference was observed for the groups G2 and G3 presenting smaller caries-lesion area when compared with their respective control areas. In the SEM analysis the G3 showed uniform surface without enamel-prism exposure. For the in situ study 60 occlusal enamel blocks were randomly divided into 4 groups in according with the treatment: G1 - Control (no treatment); G2 - Er:YAG; G3 - Nd:YAG; G4 - CO2 (n=15). The specimens were fixed in intra oral appliances and worn by the volunteers for 14d. Sucrose solution (20%) was applied to each specimen 6 times/d. As the in vitro study the samples were removed, sectioned and examined for microhardness, caries-lesion area measurements on the polarized light microcopy and morphological analyses on SEM. Variance analysis and the Fisher test were performed for the statistical analysis of the data obtained from the microhardness test (KHN) (&alpha;= 5%). The control group was statically different from G3 and G4, which present higher microhardness values and were statistical similar between them. The data of microhardness from the depth of surface were greater in proportion of distance from the surface, as 20&micro;m <30&micro;m <40&micro;m <50&micro;m. Wilcoxon test were performed for the statistical analysis of the data obtained from the caries-lesion area measurements (mm2) (= 5%) and all the groups were statically similar. Considering the results obtained from the both of studies can be concluded that the laser CO2 and Nd:YAG were able to increase the enamel acid resistance on the surface of pits and fissures.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Laser welding was investigated as a potential joining technology for alumina ceramic substrates. The objective of this study was to develop a method to preheat the ceramic using a single defocused laser beam prior to welding. Engineering ceramics are employed in a variety of systems and environments due to their unique properties. Joining technologies must be developed to facilitate the manufacture of complex or large ceramic components. Laser welding is advantageous as it forms joints rapidly, and does not introduce intermediate materials to form the bond, which can have deleterious effects. The Laser Machining System (LMS) at Queen’s University was adapted for this study. A defocused far-infrared (FIR) laser beam was positioned to overlay a focused near-infrared (NIR) laser beam; the defocused FIR beam preheated the ceramic substrate and the focused NIR beam formed the weld. A finite element model was developed in COMSOL MultiPhysics to simulate the preheating processes and to develop a preheating protocol. The protocol was implemented using the FIR beam and adjusted to achieve preheating temperatures of 1450, 1525, and 1600degC. Welds were performed on 1 mm thick alumina plates using the preheating protocols and NIR beam powers of 25, 50, and 75 W. Weld speed was held constant throughout the study at 0.5 mm/s. The preheating protocols were successful at achieving near-constant preheating temperatures, with standard deviations below 32 degrees. Partially penetrating welds were formed with the NIR beam at 25 W, and fully penetrating welds at 50 and 75 W. Large pores were present in the 25 W and 50 W welds. Minimal porosity was observed in the welds formed at 75 W. All of the welded plates experienced a transverse fracture that extended perpendicular to weld, and a longitudinal fracture extending parallel to the weld. This study shows that a fixed defocused laser beam can successfully preheat alumina substrates to the high temperatures required for welding; however, non-homogenous cooling results in fracture. Increasing the preheating beam diameter or introducing an auxiliary means to provide a controlled cool-down cycle may mitigate these effects. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-04-29 17:59:57.43