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1
Spina, Giulia. "Transparent YAG and composite ceramic materials in the system Alumina-YAG-Zirconia." Thesis, Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0023.
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Dans cette étude de doctorat, de la poudre de Y3Al5O12 (YAG) a été synthétisé avec plusieurs méthodes: atomisation, synthèse de réaction et co-précipitation. Le procédé de synthèse le plus prometteur, la co-précipitation, a été optimisé pour obtenir une poudre hautement frittable, présentant une phase pure. Le traitement approprié avant frittage, comprenant calcination, efficace dispersion et séchage homogène, a été réalisé. La poudre de YAG a été dispersée avec plusieurs méthodes, avant frittage. Grâce à la technique Spark Plasma Sintering (SPS) une évaluation très rapide de l'influence des différents traitements a été réalisée. Il a été constaté que, pour une poudre obtenue avec une telle synthèse, la méthode de dispersion est cruciale afin de obtenir une transparence élevée du materiaux fritté. En raison de l'aptitude au frittage de la poudre, du traitement approprié avant frittage et de la basse température du cycle effectué par SPS, un matériau à grains fins a été obtenu. Des mesures de spectroscopie de photoélectrons (XPS) ont été effectuées sur la poudre de YAG et sur le matériaux fritté, et plusieurs differences ont été mises en évidence. Quelques hypothèses ont été faites pour expliquer les differences observées, et certains preuves supplémentaires pour les vérifier ont été mises en avant. Une poudre composite alumine-zircone-YAG a été synthétisé à partir d'une poudre d'alumine commerciale, qui a été fonctionnalisé avec chlorures de yttrium et de zirconium. Les traitements de pré-frittage appropriées ont été effectués, comprenant une calcination à basse température et une calcination "rapide", pour favoriser la germination des petits cristallites. Deux méthodes de mise en forme, coulage et pressage, ont été réalisées. Il a été constaté que le coulage permet la production de matériaux céramiques beaucoup plus homogènes. Une caractérisation mécanique préliminaire a été effectuée. Une caractérisation spectroscopique des poudres d'alumine-YAG, traités à basse et haute température, a été réalisée. Il a été mis en évidence que l'état d'hydratation des poudres varie avec la fonctionnalisation par les chlorures. La présence de sites Y sur la surface des poudres composites a été mise en évidence par XPS et à partir des spectres infrarouges (spectroscopie infrarouge par transformée de Fourier, FTIR) des échantillons soumis à des différentes pressions de monoxide de carbone (CO)In this PhD study, Yttrium aluminum garnet (Y3Al5O12, YAG) powder was synthesised with several methods, i.e. spray drying, reaction synthesis and co-precipitation. The most promising synthesis method, i.e. co-precipitation, was optimized to obtain a pure phase, highly sinterable powder. The appropriate pre-sintering processing, i.e. calcination treatment, e fficient dispersion, homogeneous drying, were performed. YAG powder was dispersed with several methods, prior to sintering. Through Spark Plasma Sintering (SPS) a very fast assessment of the influence of the various treatments was performed. It was found that, for the synthesised powder, the dispersion method is crucial to obtain a high transparency. Due to the high sinterability of the powder and to the appropriate pre-sintering treatment, a low temperature SPS cycle was performed, and a fine-grained material was obtained. X-ray Photoelectron Spectroscopy (XPS) measurements were performed on YAG powder and on the sintered material, and several di fferences were evidenced. Some hypothesis were made to explain the observed di fferences, and some additional proofs to verify them were put forward. A composite Alumina-YAG-Zirconia powder was synthesized, starting from a commercial alumina powder, which was functionalised with Yttrium and Zirconium chlorides. The appropriate pre-sintering treatments were performed, comprising a low temperature calcination and a "fast" calcination, to favour the germination of small crystallites. Two shaping methods, i.e. slip casting and pressing, were performed. It was found that slip casting allows the production of much more homogeneous ceramic materials. A preliminary mechanical characterization was performed. A spectroscopic characterization of Alumina-YAG powders, heat-treated at low and high temperatures, was performed. It was evidenced that the hydration state of the powders changes with chlorides functionalization. The presence of Y sites on the surface of the composite powders was evidenced by X-ray Photoelectron Spectroscopy and from the di fference spectra of powdered samples subjected to various CO pressures
2
SPINA, GIULIA. "Transparent YAG and composite ceramic materials in the system Alumina-YAG-Zirconia." Doctoral thesis, Politecnico di Torino, 2012. http://hdl.handle.net/11583/2502748.
Full textAbstract:
In this PhD study, Yttrium aluminum garnet (Y3 Al5 O12 , YAG) powder
was synthesised with several methods, i.e. spray drying, reaction synthe-
sis and co-precipitation. The most promising synthesis method, i.e. co-
precipitation, was optimized to obtain a pure phase, highly sinterable pow-
der. The appropriate pre-sintering processing, i.e. calcination treatment,
efficient dispersion, homogeneous drying, were performed. YAG powder
was dispersed with several methods, prior to sintering to transparency.
Through Spark Plasma Sintering (SPS) a very fast assessment of the
influence of the various treatments was performed. It was found that, for
the synthesised powder, the dispersion method is crucial to obtain a high
transparency. Due to the high sinterability of the powder and to the appro-
priate pre-sintering treatment, a low temperature SPS cycle was performed,
and a fine-grained material was obtained.
X-ray Photoelectron Spectroscopy (XPS) measurements were performed
on YAG powder and on the sintered material, and several differences were
evidenced. Some hypothesis were made to explain the observed differences,
and some additional proofs to verify them were put forward.
A composite Alumina-YAG-Zirconia powder was synthesized, starting
from a commercial alumina powder, which was functionalised with Yttrium
and Zirconium chlorides. The appropriate pre-sintering treatments were
performed, comprising a low temperature calcination and a ”fast” calcina-
tion, to favour the germination of small crystallites. Two shaping methods,
i.e. slip casting and pressing, were performed. It was found that slip cast-
ing allows the production of much more homogeneous ceramic materials. A
preliminary mechanical characterization of the composite was performed.
A spectroscopic characterization of Alumina-YAG powders, heat-treated
at low and high temperatures, was performed. It was evidenced that the
hydration state of the powders changes with chlorides functionalization. The
presence of Y sites on the surface of the composite powders was evidenced
by X-ray Photoelectron Spectroscopy and from the difference spectra of
powdered samples subjected to various CO pressures.
3
Martial, Igor. "Systèmes laser pompés par diode à fibres cristallines : oscillateurs Er : yAG, amplificateurs Nd : yAG." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00705198.
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Au cours de cette thèse, nous nous intéressons à deux applications nécessitant des sources laser impulsionnelles : l'imagerie active et l'usinage laser. L'imagerie active nécessite des sources laser efficaces émettant dans la gamme de sécurité oculaire (entre 1,5 µm et 1,7 µm) à des cadence de l'ordre du kilohertz et produisant des énergies par impulsion de plusieurs millijoules. Les sources efficaces émettant dans la gamme de sécurité oculaire utilisent l'ion erbium. Cependant la structure électronique complexe de l'ion erbium entraîne de nombreux effets parasites qui limitent fortement l'énergie accessible lors d'un fonctionnement à haute cadence. Pour diminuer l'influence de ces effets parasites nous avons utilisé le concept de fibres cristallines dans le cadre d'une collaboration entre le Laboratoire Charles Fabry et l'entreprise Fibercryst. La géométrie des fibres cristallines, combinant les propriétés des cristaux massifs et les avantages des fibres en verre nous a permis de dépasser les limites des sources actuelles. L'usinage de matériaux requière des sources laser impulsionnelles émettant dans le proche infrarouge (1 µm) et alliant forte énergie, forte puissance crête et forte puissance moyenne. Pour réaliser de telles sources, il est nécessaire d'utiliser des milieux à gain permettant de limiter les phénomènes thermiques et les effets induit par la puissance crête (effets non-linéaires). Pour cela nous avons utilisé à nouveau le concept de fibre cristalline, dopée cette fois ci par l'ion néodyme. Ces fibres cristallines ont été utilisées comme amplificateur de puissance pour amplifier des micro-lasers fonctionnant à haute cadence (de 1 à 100 kHz) et produisant des impulsions courtes (< 1 ns).
4
Cecchini, Silvia Cristina Mafra. ""Desinfecção da Dentina Radicular pela Irradiação dos Lasers de Nd: YAG e Er: YAG: um Modelo "in vitro""." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/23/23135/tde-30082001-094604/.
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RESUMO Desinfecção da dentina radicular pela irradiação dos lasers de ND:YAG, HO:YAG e ER:YAG: um modelo in vitro A provável causa do insucesso da terapia endodôntica é a persistência de microrganismos colonizando os túbulos dentinários. Para reduzir o risco de insucesso e, se possível, o tempo despendido no tratamento endodôntico, novos equipamentos e materiais são constantemente desenvolvidos. O objetivo desta investigação foi estudar o efeito da irradiação laser intracanal na desinfecção dos túbulos dentinários de dentes bovinos recém-extraídos, utilizando-se um modelo in vitro. Os grupos irradiados pelos vários lasers foram comparados ao tratamento com hidróxido de cálcio, freqüentemente utilizado como medicação intracanal. O cemento radicular foi removido, o canal preparado e os dentes, cortados, resultando em 180 corpos de prova padronizados. Para promover a colonização bacteriana, os corpos de prova foram incubados, a 37 o C, em frascos contendo caldo de tripticase de soja e Enterococcus faecalis, o qual continha um plasmídeo que permitiu o seu crescimento em um meio seletivo com cloranfenicol. Os corpos de prova foram divididos em cinco grupos experimentais e três grupos-controle. Para irradiação foram utilizados os lasers pulsados de: Ho:YAG a 2,1 µm; Nd:YAG (1,06 µm); e Er:YAG (2,94 µm) com e sem refrigeração ar/água. Os grupos tratados receberam três parâmetros diferentes de irradiação com cada tipo de laser: energia abaixo do limiar de modificação física (physical modification threshold - ½ do PMT) por 60s; no limiar (PMT) por 60s; e, acima do limiar (120s). O Grupo 5 recebeu sete dias de tratamento com hidróxido de cálcio. Como controles, três espécimes para cada grupo receberam água estéril (controle negativo), três receberam KI3, após exposição à bactéria (controle negativo) e três não receberam tratamento após exposição à bactéria (controle positivo). A quantidade de bactérias foi estimada mediante a contagem de unidades formadoras de colônias (u.f.c.). De modo a avaliar, paralelamente, se os comprimentos de onda laser utilizados no experimento poderiam ser absorvidos pelo E. faecalis, foram obtidos espectros de absorção no UV, VIS e IR, por meio de espectroscopia. A análise estatística mostrou uma redução bacteriana como segue: Ho:YAG > hidróxido de cálcio > Nd:YAG > Er:YAG com refrigeração ar/água > Er:YAG sem refrigeração ar/água. Houve uma significativa redução bacteriana no grupo irradiado pelo Ho:YAG no limiar de modificação PMT (50 mJ, 10 Hz, 66 J/cm 2 , por 120s), seguida pelo Ho:YAG a 50 mJ, 10 Hz, 33J/cm 2 , por 60s e pelo grupo que recebeu hidróxido de cálcio. Os dois últimos grupos não apresentaram diferenças estatísticas significativas. O espectro de absorção pelas bactérias (E. faecalis) nas faixas dos comprimentos de onda do UV e VIS apresentou picos de absorção em 361 nm e em 377 nm (UV). Já o infravermelho próximo revelou uma baixa absorção pelo microrganismo testado.SUMMARY Disinfection of intracanal dentin by Nd:YAG, Ho:YAG and Er:YAG laser irradiation: an in vitro model A possible cause for root canal failure is the persistence of bacteria that have colonized dentinal tubules. To reduce this risk and, if possible, to also shorten the time-consuming endodontic therapy, new equipment and materials are constantly being introduced. The aim of the present investigation was to study the effect of disinfection of dentinal tubules by intracanal laser irradiation using an in vitro model. The groups irradiated by various lasers were compared with calcium hydroxide, a material frequently used as intracanal medication between appointments. Freshly extracted, intact bovine incisors were used. The root cementum was removed and the teeth cut to produce 180 standardized specimens. For bacterial colonization, specimens were incubated at 37 o C in test tubes with Tryptic Soy Broth and Enterococcus faecalis, which carried a plasmid that allowed the growth in a selective medium containing chloramphenicol. The specimens were divided in five treatment groups and three control groups. For irradiation, pulsed delivered Ho:YAG laser at 2.1 µm, Nd:YAG laser (1.06 µm), and Er:YAG and Er:YAG laser (2.94µm) with and without air/water coolant, were used. Lasers groups received three different laser settings for treatment: output energy below the physical modification threshold (½ of PMT) for 60 sec, at the PMT for 60 sec and above the PMT (120 sec). Group 5 received a seven-day treatment with calcium hydroxide. As controls, three specimens for each treatment group received sterile water instead of bacteria (negative control), three received iodine potassium-iodide after bacterial exposure (negative control), and three did not receive treatment after bacterial exposure (positive control). The number of bacteria was estimated by counting CFU. In order to evaluate whether the lasers used in the experiment could be absorbed by the bacteria E. faecalis, an UV, VIS and NIR spectra were obtained using a spectrophotometer. Statistical analysis showed the bacterial reduction as follow: Ho:YAG laser > hidróxido de cálcio> Nd:YAG laser > Er:YAG laser with air/water coolant > Er:YAG laser without air/water coolant. There was a significantly higher bacterial reduction in the group irradiated by the Ho:YAG at the PMT (50mJ, 10 Hz, 66 J/cm 2 for 120 sec), followed by Ho:YAG irradiated at 50mJ, 10 Hz, 33 J/cm 2 for 60 sec, and the group that received calcium hydroxide. The latter two groups were not significantly different. The UV and VIS absorbance spectrum presented two absorbance peaks at 361nm and 337nm (UV). The NIR spectrum revealed a very low absorbance by the E. faecalis.
5
Andersson, Martin, and Martin Svensson. "Nd YAG laser welding in Titanium-6242." Thesis, University West, Department of Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-764.
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Matthewson, Kenneth. "Studies on therapeutic neodymium YAG laser endoscopy." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241407.
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Badran, Zahi. "Utilisation du laser Er :YAG en parodontologie." Nantes, 2012. http://www.theses.fr/2012NANT33VS.
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La parodontite chronique est une maladie inflammatoire d'origine bactérienne. Elle se traduit par la perte d'attache et l'apparition d'hypersensibilités dentinaires, après exposition du cément radiculaire suite aux récessions gingivales. La prise en charge de cette pathologie repose sur une thérapeutique étiologique mécanique, qui est réalisée avec des inserts ultrasoniques ou des curettes manuelles. Depuis quelques années, le laser Er :YAG a été introduit comme alternative pour le traitement des parodontites chroniques, aussi bien au niveau du débridement radiculaire que pour le traitement de l'hypersensibilité dentinaire. Dans ce travail, nous avons voulu dans un premier temps, comparer le débridement laser au traitement mécanique conventionnel. Une étude clinique pilote a été menée dans le cadre d'un protocole de recherche clinique. Les résultats de cette étude montrent que le débridement au laser Er :YAG donne des résultats cliniques au moins similaires au surfaçage radiculaire manuel avec une supériorité en termes de gain d'attache clinique. Dans un second temps, nous avons voulu explorer l'action du laser Er :YAG sur l'hypersensibilité dentinaire. Une étude menée in vitro pour observer l'effet microscopique de ce laser sur les tubuli dentinaires exposés, a permis d'observer l'oblitération de ces derniers. Un cas clinique d'hypersensibilité traité par le laser a permis de confirmer ces résultats. Dans la limite des résultats de ce travail, nous pouvons conclure que le laser Er :YAG pourrait être une alternative intéressante dans le cadre de la prise en charge des parodontites chroniquesChronic periodontitis is an inflammatory disease with an infectious bacterial etiology. One of its clinical manifestations is dentinal hypersensitivity after root cementum exposure. Its clinical management consists of implementing proper oral hygiene, then performing a mechanical cause-related therapy. The latter is realized using ultrasonic devices or manual curettes. Er:YAG laser debridement was introduced as a therapeutic tool for periodontal root debridement. We wanted to compare the latter to conventional mechanical scaling and root planning, in terms of clinical parameters. A pilot clinical study was carried at the CHU of Nantes. We found that both therapies lead to significant improvements of clinical periodontal parameters. No significant superiority between both modalities was found, except for clinical attachment level. On the other hand, Er:YAG laser was found to be capable of treating dentinal hypersensitivity. An in vitro study permitted te observe the microscopical obliteration of dentinal tubules after laser irradiation. A clinical case of dentinal hypersensitivity was also managed using the Er:YAG laser. Within the limit of the study, Er:YAG laser debridement could be an alternative to conventional mechanical therapy
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Bonati, Guido. "Integration von Diodenlasern in modulare Hochleistungs-Nd: YAG-Laser." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=965090531.
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Risse, Enrico. "Kontinuierlich angeregte und aktiv gütegeschaltete Oszillator-Verstärker-Systeme hoher Strahldichte durch Einsatz von Faser-Phasenkonjugatoren." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969665881.
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Schöne, Wolfram. "Theoretische und experimentelle Untersuchung thermischer Effekte in diodengepumpten Hochleistungs-Nd:YAG-Stablasern." [S.l. : s.n.], 1998. http://deposit.ddb.de/cgi-bin/dokserv?idn=954722914.
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Bode, Markus. "Abstimmbare Einfrequenz-Strahlquellen hoher Stabilität im infraroten, sichtbaren und ultravioletten Spektralbereich." [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=956684122.
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Knoke, Stefan. "Einfrequenzbetrieb von diodengepumpten Nd:YAG-Hochleistungslasern in Stab- und Slabgeometrie." [S.l. : s.n.], 1998. http://deposit.ddb.de/cgi-bin/dokserv?idn=956329845.
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Lange, Falk. "Stabilisierung der Ausgangsleistung eines resonatorintern frequenzverdoppelten Nd:YAG-Lasers." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967557119.
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Ernst, Holger. "Optimierung und Anwendung eines diodengepumpten, hochrepetierenden 3mm-Er:YAG-Lasers [3-my-m-Er:YAG-Lasers]." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972358870.
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Quetschke, Volker Marcel. "Korrelationen von Rauschquellen bei Nd:YAG-Lasersystemen." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969654669.
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Hilburger, Michaela. "Holmium YAG Laserlithotrypsie in der Behandlung der Urolithiasis." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-116955.
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Rodriguez-Pena, Luis. "Assemblage aluminium : Acier par faisceau laser Nd : YAG." Ecully, Ecole centrale de Lyon, 2005. http://bibli.ec-lyon.fr/exl-doc/lrodriguezpena.pdf.
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Les réductions de consommation de carburant imposées par les nouvelles normes internationales imposent un allégement des véhicules et l'utilisation d'alliages légers pour certaines parties des structures. Se pose alors le problème de l'assemblage de ces parties en aluminium sur celles en acier. Le principal problème rencontré lors de la réalisation de telles soudures par des procédés conventionnels est la formation de composés intermétalliques qui réduisent les performances des assemblages. En revanche, le procédé de soudure par faisceau laser autorise un contrôle optimal des conditions thermiques au sein de la soudure et permet de limiter la formation de ces phases fragiles. Ce travail présente les résultats de l'étude de faisabilité réalisée en utilisant deux fils d'apport différents à savoir le ZnAl-30 et le AlSi-12. L'étude a montré la forte influence du type de configuration utilisée sur la présence d'inermétalliques et les propriétés mécaniques finales de l'assemblageThe reduction of consumption of fuel of internal combustion motors, imposed by the new anti-pollution and energy saving laws may be attained by reducing the weight of vehicles, introducing, for example, aluminium sections into the main steel car-body. Laser brazing is a process which can be used to perform such a junction. The main problem of welding this kind of combination of materials with conventional processes is the potential formation of inter-metallic phases, which reduces the good performance of the joint. Laser brazing allows a very good control of the thermal development of the joint, with a limited precipitation of these brittle phases. This work presents the results of a feasibility study made with ZnAl-30 and AlSi-12 as filler metal. The study shows that the type of configuration used for the assembly has a particular influence on the formation of brittle phases and consequently on the mechanical performance of the joint
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Mazerolle, Denis. "Resonateur a cristaux de corindon et de yag." Paris 6, 1988. http://www.theses.fr/1988PA066410.
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Ribau, Humberto Miranda. "Soldadura laser pulsado Nd: YAG entre metais dissimulares." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/23358.
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Mestrado em Engenharia MecânicaA presente investigação consiste no estudo experimental das propriedades mecânicas induzidas pela soldadura laser em chapas de materiais metálicos dissimilares, nomeadamente, aço de alta resistência dual-phase (DP) 600 com aço de alta resistência dual-phase (DP) 1000 e liga de alumínio AA6060-T6 com liga de titânio Ti-6Al-4V. No caso dos aços dual-phase, o estudo foi realizado em amostras de 0,8 mm de espessura, numa junta do tipo topo a topo. Após a seleção dos parâmetros mais adequados para a soldadura, foram efetuados ensaios de tração aos provetes soldados, com o objetivo de determinar as propriedades mecânicas e avaliar a influência dos parâmetros do laser. Em relação à ligação de alumínio com titânio, esta foi feita numa junta de sobreposição dupla em amostras de 1,9 e 0,9 mm de espessura, respetivamente. Do mesmo modo que os aços, foram também variados os parâmetros do laser, de modo a se obter os mais adequados, para posteriormente se efetuar ensaios de tração. Variou-se também o sítio onde o feixe laser incide na junta de sobreposição para melhor avaliar a soldadura.
The aim of this thesis consists of an experimental study of the mechanical properties induced by the laser welding in dissimilar metal, namely, dual-phase steel 600 with dual-phase steel 1000 and aluminium alloy AA6060-T6 with titanium alloy Ti-6Al-4V. In the case of the dual-phase steels, the study was carried out on 0,8 mm plates, in a butt joint type. After selecting the most appropriate parameters for the welding, tensile tests were performed on welded specimens with the purpose to find the mechanical properties and evaluate the influence of the laser parameters. The aluminium - titanium union was accomplished on a double-lap joint on 1,9 mm and 0,9 mm plates, respectively. Just like the situation of the steels, the laser parameters were too varied with aim to obtain the most appropriate parameters, to later perform tensile tests. It was also changed the place where the laser beam impacts on the specimen, to better analyse the welding.
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Mazerolle, Denis. "Résonateurs à cristaux de corindon et de YAG." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37616201x.
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Rodriguez-Pena, Luis Langlade Cécile. "Assemblage aluminium Acier par faisceau laser Nd : YAG /." [S.l.] : [s.n.], 2005. http://bibli.ec-lyon.fr/exl-doc/lrodriguezpena.pdf.
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CHEVALLIER, NATHALIE. "Le traitement des lesions endobronchiques par laser nd-yag : a propos de 153 cas, d'aout 1982 a mai 1987." Toulouse 3, 1988. http://www.theses.fr/1988TOU31106.
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Kuzminykh, Yury. "Crystalline, rare-earth-doped sesquioxide and YAG PLD-films." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981073182.
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Krüger, Reinhard. "Pyrolyse- und Sinterverhalten Sol-Gel-abgeleiteter Al2O3-YAG-Fasern." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969687540.
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Shen, Hanfei M. 1979. "Ultrashort pulse generation with solid state Cr⁴⁺:YAG laser." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87850.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2003.Includes bibliographical references (p. 127-130).
by Hanfei M. Shen.
S.M.
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Sauer, Herbert. "Tratamento transureteroscópico do cálculo ureteral com HOLMIUM: YAG laser." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/5/5153/tde-19032007-104915/.
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Objetivo: O Holmium:YAG laser é o método de litotripsia intracorpórea para cálculos urinários mais recentemente introduzido em nosso meio. O objetivo deste estudo é analisar a eficácia e as complicações imediatas do tratamento de pacientes com cálculos ureterais com essa fonte de energia. Casuística e Métodos: Foram tratados 16 pacientes, nove homens e sete mulheres, portadores de cálculos ureterais sintomáticos, maiores ou iguais a 6 mm, ou com evolução superior a 30 dias. A média de idade foi 42 anos (6- 68 anos). Quatro cálculos estavam localizados no ureter superior, seis no ureter médio e seis no ureter inferior. A técnica empregada foi a de vaporização do cálculo com Holmium:YAG laser, através de ureteroscopia. Utilizou-se exclusivamente ureteroscópio semi-rígido de 7 Fr. Resultados: A taxa de sucesso obtida foi de 87,5%, sem diferença estatisticamente significativa em relação ao relatado na literatura. Todos os cálculos foram fragmentados. Os dois insucessos da série ocorreram com cálculos localizados em ureter superior, em que fragmentos foram deslocados para o rim. As complicações observadas foram três perfurações ureterais e dois casos de febre. Conclusão: O Holmium:YAG laser é eficaz no tratamento endoscópico do cálculo ureteral. Medidas destinadas a prevenir a migração retrógrada do cálculo ou de seus fragmentos devem ser tomadas, principalmente no tratamento dos cálculos localizados em ureter superior. A litotripsia com Holmium:YAG laser não é, entretanto, um método isento de complicações, particularmente no que se refere ao tratamento de cálculos impactados de ureter superior.Objetive: Holmium:YAG laser is the more recently method of intracorporeal lithotripsy of urinary calculi introduced in our area. The purpose of this study is to analyze the technique and to evaluate the immediate results and complications in the treatment of patients with ureteral calculi. Casuistry and Methods: Sixteen patients were treated, nine men and seven women, carrying symptomatic ureteral stones, bigger than 6 mm or with evolution superior to 30 days. The average age was 42 years old (6-88 years old). Four stones were localized in upper ureter, six in middle ureter, and six in lower ureter. The technique employed was the vaporization of the stone with Holmium:YAG laser, through ureteroscopy. It was used exclusively 7-Fr semirigid ureteroscope. Results: The rate of success attained was of 87.5%, with no statistically significant differences regarding the reports in literature. All the stones were fragmented. The two failures of the series occurred with stones localized in upper ureter, in which fragments were displaced to kidney. The complications observed were three ureteral perforations and two fever cases. Conclusion: Holmium:YAG laser is effective in the endoscopic treatment of ureteral stones. Measures aimed at preventing retrograde migration of stones or fragments should be taken, mainly when the stone are located in the upper ureter. However, lithotripsy with Holmium:YAG laser may be associated with complications, particularly in what concerns the treatment of impacted stones.
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Ватаманюк, Н. В. "Основні переваги лікування початкової стадії генералізованого пародонтиту YAG лазером." Thesis, БДМУ, 2020. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/17839.
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Kopecký, Lukáš. "Svařovaní ocelí s rozdílnými vlastnostmi pomocí Yb-YAG laseru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230042.
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Diploma theses is focused on welding experiment of maraging steel by use Yb-YAG laser. Experimet is based on testing of combination steel 11321 and maraging steel. Domex420MC, Domex720MC a QSE380. In theoretical part there are described laser technology of welding, weld defect, maraging steel and inspection of welded joints. In experimental part there are porposed test and made mechanical test of weld as transverse tensile test, bend tests, Erichsen cupping test, Vickers hardness test and makroscopic and microscopic examination of welds. In conclusion there are analysis of the experiment results.
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Chlád, Luboš. "Svařovaní ocelí s rozdílnými vlastnostmi pomocí Yb-YAG laseru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230535.
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The master's thesis presents an experiment of welding of high strength steel Docol 1200 M and of steel DC01 by the fiber Yb-YAG laser. The experiment is based on testing welds which were made during the experiments. The lasers, laser technologies of welding, steels of higher strength, tailored blanks technology and testing of welds are described in the theoretical part. The practical part contains description and evaluation of tests of welds – transverse tension test, Vickers hardness test, Erichsen cupping test and macrostructure and microstructure test. The final evaluation results of the experiment are presented in the conclusion of the master's thesis.
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Czesnakowska, Ada. "Développement d'une source de lumière blanche grâce au couplage d'une diode laser et d'un luminophore adaptés." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30180/document.
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Ces dernières années les semi-conducteurs à base de InGaN sont devenus attractifs pour des applications d'éclairage. Les sources blanches à base de LED sont de plus en plus utilisées en raison de leur petite taille, leur longue durée de vie et leur faible consommation d'énergie. Malheureusement les LED utilisées dans ces dispositifs subissent une perte de rendement quantique externe quand leur courant d'alimentation augmente. Ceci se traduit par un décalage du maximum d'émission ainsi qu'un élargissement spectral. Ces variations d'émission impactent la conversion de lumière bleue en lumière blanche, ce qui diminue l'efficacité du procédé. Une méthode alternative pour obtenir de la lumière blanche en travaillant à forte puissance serait l'utilisation de diodes laser (DL) à la place des LED. Contrairement aux LED, elles sont moins affectées par les pertes d'efficacité. La puissance lumineuse et le rendement quantique externe des diodes laser augmentent linéairement avec le courant d'alimentation, ce qui maintient la stabilité de la lumière blanche produiteIn past few years InGaN-based semiconductors have attracted much more attention for application in solid-state lighting sources. Recently, their usage is constantly increasing on worldwide market. High-brightness white LEDs have been used due to their size, long life and energy saving. However, LEDs used in light sources suffer from a loss in external quantum efficiency as an operating current increases. This loss may lead to a shift in peak emission wavelength and broadening of emission spectrum. Laser diodes, in contrary to LEDs, do not suffer this loss. The output power increases linearly with injection current. Moreover, they can reach higher luminosity, for the same power, than LEDs. Additionally, laser-based devices can be operated in reflection mode, allowing for the phosphor to be placed on a reflection substrate that may also act as a heat sink to effectively dissipate heat away from the phosphor
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BLIN, JEAN-LOUIS. "Le laser holmium yag dans la chirurgie arthroscopique des lesions meniscales." Lille 2, 1992. http://www.theses.fr/1992LIL2M105.
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DAMON, HENRI. "Traitement palliatif par le laser nd-yag des cancers du rectosigmoide." Saint-Etienne, 1991. http://www.theses.fr/1991STET6405.
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Beacco, Claire. "Volatilisation tissulaire au laser nd:yag continu : etude experimentale et modelisation." Lille 2, 1995. http://www.theses.fr/1995LIL2P255.
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Zarour, Hassane. "Lasers et malformations vasculaires superficielles : mise au point : etude preliminaire sur un nouveau type de laser (le laser yag dedouble en frequence)." Aix-Marseille 2, 1991. http://www.theses.fr/1991AIX20819.
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Melo, Marina Lins Maymone de. "Avaliação do Uso do Laser Er:Yag no Tratamento da Osteonecrose Mandibular Induzida por Bisfosfonatos: estudo experimental em ratos." Universidade Federal de Pernambuco, 2014. https://repositorio.ufpe.br/handle/123456789/12791.
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REUNI-UFPE
O objetivo deste estudo foi comparar, em modelo animal, o tratamento da osteonecrose dos maxilares induzida por bisfosfonatos (OMIB) realizado por cirurgia com laser Er:YAG com a cirurgia convencional. Foi realizado um estudo controlado experimental in vivo, utilizando 12 ratos Wistar machos, divididos em três grupos: controle (C), cirurgia convencional (CONV) e cirurgia a laser (LAS). Os animais foram tratados por 12 semanas com uma injeção intra-peritoneal semanal utilizando soro fisiológico na dosagem de 0,1ml/100g (grupo C) ou ácido zoledrônico (ZA) com doses de 0,15mg/Kg (grupos CONV e LAS). Os animais foram submetidos a exodontia de primeiro e segundo molares mandibulares para indução da OMIB, e então tratados com curetagem (grupo CONV) ou ablação a laser de Er:YAG (grupo LAS). Após a eutanásia, as mandíbulas foram removidas, fixadas em formol a 10% e analisadas através microtomografia computadorizada (microCT) para avaliação do padrão de trabeculado e densidade óssea. Os espécimes foram então processados e corados em HE para avaliação microscópica.A análise das imagens do microCT mostrou presença de sequestros ósseos, com aumento dos espaços medulares do osso esponjoso no grupo CONV. O trabeculado do grupo LAS apresentou padrão semelhante ao grupo C. A densidade óssea não apresentou diferença estatisticamente significante entre os grupos. A análise microscópica evidenciou reparo ósseo alveolar avançado (acima de 60%) em todos os animais do grupo C e 75% do grupo LAS, sendo ausente em 50% do grupo CONV. O laser de Er:YAG apresenta-se como uma importante estratégia terapêutica para o tratamento cirúrgico da OMIB, sendo superior à curetagem.
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Yuh-Ping, Tong. "Femtosecond optical source based on a Cr'4'+:YAG laser." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243294.
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Conlon, Patrick Joseph. "Ultra-short pulse generation with a Cr'4'+:YAG laser." Thesis, Imperial College London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320180.
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PEIXOTO, CLARISSA FERREIRA. "SURFACE CLEANING OF HISTORICAL PAPER DOCUMENTS USING ND: YAG LASER." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=22327@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
A conservação e restauração de obras de arte e objetos de interesse histórico se afirma como ciência que agrega várias áreas do conhecimento. O processo de limpeza superficial se impõe como ponto fundamental e crítico em todas as intervenções, pois, tradicionalmente, envolve processos invasivos e de difícil controle. O método de limpeza a laser se coloca como solução viável, e amplamente difundida em intervenções realizadas em mármores e metais. Estudos demonstram a viabilidade na utilização do laser Nd YAG para a limpeza de papel. O suporte a ser tratado é um papel de pasta mecânica, da década de 30, que foi irradiado com feixe de 532nm. Visando a otimização do modo operacional, os parâmetros tempo de exposição, frequência, energia depositada e distância focal foram alterados. A fim de comparação, foi realizado limpeza aquosa para estabelecer a eficiência dos métodos tradicional e à laser. A análise dos resultados foi baseada na avaliação óptica, utilizando o método CIELab, e através da Microscopia Eletrônica de Varredura MEV.
Conservation and restoration of artworks and objects of historical interest is a science that combines several areas of knowledge. The surface cleaning step is an essential and critical process in every conservation procedure, because it involves traditionally invasive processes that are hard to control. The laser cleaning method is a viable solution, and in widespread interventions in marble and metal. Studies demonstrate the viability of the use Nd YAG laser for cleaning paper. The support to be treated is a paper of mechanical pulp, from the 30s, by 532nm laser beam. The evaluated parameters were the operational mode, the exposure time, the energy deposited and the focal length parameters. Classical wet method was used for comparison, aqueous cleaning was performed to establish the efficiency of traditional methods and laser. The paper surface was characterized by visual inspection, CIELab method and scanning electron microscopy SEM. Some conditions did clean the surface with minor damage.
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Ramanujam, Prabhu. "Synthesis and processing of nanocrystalline YAG (Yttrium Aluminium Garnet) ceramics." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/16651.
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Transparent ceramics are used in a variety of applications such as protective visors, thermo-graphic lens, night vision devices and windowpane of an armed vehicle, missile domes and in aircrafts. Yttrium Aluminium Garnet (YAG, Y3Al5O12) exhibits uniform index of refraction without birefringence owing to its cubic crystal structure and offers a range of optical and mechanical properties that makes it suitable for transparent applications.
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Mondin, Linda. "Stabilisation de fréquence de laser Nd-YAG pour applications spatiales." Nice, 2005. http://www.theses.fr/2005NICE4046.
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Les lasers stabilisés à long terme sont utilisés dans de nombreux domaines en métrologie et constituent la base de toute la recherche expérimentale en spectroscopie à très haute résolution. Ce mémoire décrit mon travail de thèse sur les lasers à Nd:YAG stabilisés en vue d'applications spatiales (missions de physique fondamentale ou géodésie). Les montages doivent satisfaire critères de compacité, stabilité mécanique, robustesse et fiabilité. On traite les références utilisables pour le long (moléculaire) et le court (mécanique) terme ainsi que leurs limitations principales. L'analyse et le choix de ces références de stabilisation seront couplés avec le choix des techniques de stabilisation (PDH, Tilt-Locking, Modulation Transfer). Dans les techniques de stabilisation, celle de Pound-Drever-Hall (PDH) est devenue un classique car elle donne les meilleurs performances connues à ce jour surtout à court terme. Pour réduire le nombre de composants actifs, nous avons aussi implanté une technique dite de Tilt-Locking, que je compare avec celle de PDH dans le cas d'une référence Fabry-Perot monolithique. Les performances théoriques sur le long terme et les efficacités quantiques sont inter-comparées. On présente les montages expérimentaux et les résultats obtenus (lasers stabilisés sur Fabry-Perot et Iode moléculaire). On a calibrer les dérives de fréquence du Fabry-Perot, ce qui permettra de présenter des solutions obtenues analytiquement et numériquement pour l'asservissement en longueur de cette référence mécanique. Des suggestions de prolongation de ces travaux sont suggérés en conclusion et, en appendices, les détails de dimensionnement des bruits de LISA, le rappel théorique des ondes de gravitation, ainsi que divers simulations de calculs effectués, sont présentéesLong term stabilised lasers are used in a multitude of metrological applications and are the basis of experimental research in very high resolution spectroscopy. This document describes my thesis work on stabilised Nd:YAG lasers in view of space applications (for fundamental physics experiments and geodesy). All experiments must satisfy criteria of compactness, mechanical stability, robustness and reliability. I will describe the possible references for the long (molecules) and the short (resonators) term time intervals with their principal limitations. The discussion leading to their choice is actually connected to the stabilisation techniques to be adequately implemented (PDH, Tilt-Locking, Modulation transfer). Among the stabilisation techniques, the Pound-Drever-Hall (PDH) technique is now a classic as it produces the best performance in short term, so far. To reduce active components, we have also implemented a DC technique called Tilt-Locking and I will compare with PDH in the case of a monolithic Fabry-Perot reference. Theoretical performances on the long term and quantum efficiencies will be compared for different techniques. The schematic principles of the experiences and the results I have obtained for stabilised lasers on Fabry-Perot and molecular iodine are presented. We calibrated the Fabry-Perot drifts, this allows me to point out analytical and numerical solutions to control the length of this mechanical reference. Finally suggestions for further work will be approached and, in the appendices, details about noise order of magnitudes for LISA, a theoretical overview of gravitational waves as well as different simulations and calculations are presented
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LABALETTE, MARIE-LUCE. "Iridotomie au laser argon et/ou yag : a propos de 103 yeux." Lille 2, 1991. http://www.theses.fr/1991LIL2M148.
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Riul, André. "Estudo das propriedades luminescentes de íons Terras Raras em matrizes compósitas à base de alumina obtidas por pirólise de aerossol." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-01032018-071617/.
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A pirólise de aerossóis ou spray pirólise (SP, do inglês Spray Pyrolysis) é uma importante metodologia para a obtenção de luminóforos e diferentes matrizes sólidas em dimensões nano a micrométricas, desde a escala laboratorial ao nível industrial. O arranjo experimental permite o ajuste de uma ampla faixa das temperaturas de pirólise (100 a 1000 °C), possibilitando que sistemas de interesse sejam obtidos em uma única etapa. Contudo, não existe um controle eficiente do ambiente de coordenação do íon emissor e a simetria deste será consequência do ambiente imposto pela estrutura cristalina ou amorfa da matriz sólida final. O tratamento térmico rápido, característico desta metodologia, pode dificultar a total cristalização de determinadas fases e, sendo assim, uma heterogeneidade nos sítios de simetria será obtida. Este trabalho tem como objetivos estudar as propriedades luminescentes de aluminatos dopados com íons terras raras. E nesse sentido, propuseram-se inicialmente metodologias para a obtenção de diferentes matrizes inorgânicas por SP visando o estudo do sítio de coordenação de íons lantanídeos. Num primeiro momento, foi proposto a metodologia para a obtenção de matrizes inorgânicas por SP mantendo a estrutura do sítio de coordenação de íons lantanídeos. Nesta estratégia foi escolhido um meio inorgânico estável, protegendo os íons terras raras ativos de perturbações externas, estável tanto do ponto de vista químico e térmico durante o processo de pirólise, YVO4:Eu3+ foi o escolhido por possuir sítios de simetria bem definidos e por ser um composto de grande interesse tecnológico. Ainda dentro dos objetivos, estudou a síntese de aluminatos dopados com íons ítrio visando à formação de sistemas compósitos (-Al2O3 / YAG). Os compostos foram primeiro obtidos pela co-dopagem com íons Eu3+ visando um estudo estrutural, e posteriormente, sistemas contendo Itérbio/Érbio e Itérbio/Túlio foram preparados, visto que são escassos os trabalhos que descrevem a síntese de partículas com propriedades de conversão ascendente de energia pela metodologia de pirólise de aerossol. A fase YAG foi obtida para diferentes proporções de Y3+/Al3+, porém também foi obtido a fase meta estável YAlO3 (YAH) em uma única etapa, sendo que essa fase é reportada na literatura como de difícil obtenção. Os compostos obtidos foram caracterizados principalmente por espectroscopia de fotoluminescência (espectros de emissão/excitação e tempos de vida), espectroscopia vibracional, Difratometria de raios X de pó, microscopia eletrônica e análise térmicaSpray Pyrolysis (SP) is an important methodology to obtain phosphors and different solid matrices in a nano-to-micrometric dimension, ranging from the laboratory scale up to the industrial level. The experimental arrangement allows the adjustment of a wide range of pyrolysis temperatures (100 up to 1000 ° C), which allows the system of interest obtention in a single step. However, there is no efficient control concerning the emitter ion coordination environment, and its symmetry will be a consequence of the environment imposed by the resultant solid matrix crystalline or amorphous structure. The rapid thermal treatment, which is the main characteristic of this methodology, it might hinder the total crystallization of certain phases and, thus, heterogeneity in the symmetry sites will be obtained. This study aims to study the luminescent properties of aluminates doped with Rare Earth (RE) ions. Under this perspective, several methodologies have been initially proposed in order to obtain different inorganic matrices using SP to study lanthanides coordination sites. At first, the methodology for obtaining inorganic matrices through SP maintaining the structure of the lanthanide ion coordination site was proposed. In this strategy, a stable (both chemically and thermally) inorganic medium was chosen, protecting the active rare earth ions from external perturbations during the pyrolysis process. YVO4:Eu3+ was selected for presenting well-defined symmetry sites and for its wide technological appeal. Moreover, the synthesis of aluminates doped with yttrium ions to form composite systems (-Al2O3 / YAG) has been carried out. The compounds were first obtained by co-doping with Eu3+ ions for a structural study. Subsequently systems containing Ytterbium / Erbium and Ytterbium / Yttrium were prepared, since there is a lack of description of these systems in the literature when its considered the synthesis of particles with energy upward conversion properties by aerosol pyrolysis methodology. The YAG phase was obtained using different proportions of Y3+/Al3+, but the stable YAlO3 (YAH) phase was also attained in a single step, even being reported as difficult to achieve in the literature. The compounds synthesized were characterized mainly by photoluminescence spectroscopy (emission/excitation spectra and lifetimes), vibrational spectroscopy, powder X-ray diffraction, electron microscopy and thermal analysis
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Suárez, Menéndez Marta. "Materiales cerámicos policristalinos de AI2 O3 y YAG con funcionalidad óptica." Doctoral thesis, Universidad de Oviedo, 2009. http://hdl.handle.net/10803/11160.
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En esta memoria se estudia la obtención de materiales policristalinos de alúmina y YAG (granate de itrio y aluminio) transparentes en el infrarrojo cercano y en el visible, empleando una ruta de procesamiento cerámico y evitando la introducción de segundas fases. La condición general que cualquier material no absorbente debe cumplir para evitar fenómenos de dispersión de luz y, por lo tanto, pérdidas de calidad óptica, es la homogeneidad espacial con respecto a sus propiedades dieléctricas. Por lo tanto, el tamaño de poro y, en el caso de materiales birrefringentes, el tamaño de grano, son los parámetros más importantes que es necesario controlar.En el caso de la alúmina, el empleo de métodos de sinterización convencionales produce un crecimiento de grano y una pérdida de transparencia. Para evitar este problema, se han seguido dos vías distintas: primero, se ha empleado un método de dopaje coloidal con alcóxidos de aluminio. Los resultados obtenidos muestran que este proceso modifica la superficie de los granos de alúmina mediante la nucleación y crecimiento de nanopartículas de [alfa]-alumina, consiguiendo un material final con una única fase. Se ha estudiado también cómo la modificación superficial de los granos de alúmina de la matriz cambia los mecanismos de difusión atómica durante la sinterización del material. Segundo, la sinterización de la alúmina pura y dopada mediante métodos no convencionales (SPS, Spark Plasma Sintering) ha permitido obtener muestras de alúmina transparentes, destacando que la alúmina dopada muestra mejores valores de transmitancia en línea. En el caso del YAG, se han empleado dos rutas de síntesis distingas: sol-gel y coprecipitación inversa, observándose que la segunda vía de síntesis, empleando cloruros como precursores, permite obtener un material de YAG puro a una temperatura de calcinación más baja y con un alto rendimiento. El material sintetizado se seca mediante un proceso de liofilización y se sinteriza mediante SPS obteniéndose un material de YAG con una elevada transmitancia. Finalmente, el YAG se ha dopado con un 1% atómico de Nd3+ empleando un método de procesamiento coloidal, proporcionando una funcionalización óptica adicional a dicho material: la emisión laser.
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Seixas, Fabio Heredia. "Avaliação do uso do laser de Er: YAG sobre a remoção da camada de 'smear' das paredes dos canais radiculares com achatamento mésio-distal submetidos à instrumentação rotatória." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-19022004-120106/.
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No tratamento endodôntico, várias fases de igual importância são necessárias para a realização de uma terapêutica bem sucedida, entre elas podemos citar a instrumentação. Apesar de todas as técnicas e instrumentos propostos para a Endodontia, o sucesso esperado ainda não foi alcançado. Tanto a instrumentação manual quanto à rotatória não resulta na limpeza das áreas polares dos canais radiculares com achatamento mésio-distal. No intuito de obter melhor resultado clínico, avaliou-se in vitro a remoção da camada de smear das paredes dos canais radiculares de 40 dentes incisivos inferiores portadores de achatamento mésio-distal submetidos à instrumentação rotatória por meio da técnica Free Tip Preparation, utilizando o laser de Er: YAG nos parâmetros de 140 e 250 mJ. Para tanto, a fibra óptica do aparelho foi deslocada lentamente, com velocidade de 2 mm/s, até o orifício cervical na câmara pulpar, na parede vestibular e lingual da raiz; e sua eficácia na remoção da smear foi comparada aos grupos onde se utilizou apenas Hipoclorito a 2,5% e Hipoclorito de sódio a 2,5% alternado com EDTA a 17%. Os dentes foram analisados por meio de microscopia eletrônica de varredura, e as fotomicrografias das áreas mais representativas dos terços médio e apical foram avaliadas por três examinadores diferentes, com grau mínimo de Mestre, que observaram a quantidade da camada de smear presente nas amostras em relação a três padrões. Os examinadores, sem que tivessem o conhecimento prévio de qual dos grupos estavam avaliando, atribuíram escores de 1 a 4 as fotomicrografias, de acordo com a quantidade da camada de smear visualizada. Os dados obtidos foram submetidos à análise estatística não-paramétrica, comparando-se os diferentes grupos estudados (teste de Kruskal-Wallis) e os terços radiculares (teste de Wilcoxcon). Os resultados mostraram que, quanto à quantidade da smear encontrada nos grupos estudados, o grupo que utilizou Hipoclorito a 2,5% alternado com EDTA apresentou os canais radiculares mais limpos seguido do grupo do laser 250 mJ e posteriormente pelos grupos do laser Er: YAG a 140 mJ e do hipoclorito a 2,5%, que não apresentaram diferença estatisticamente significante entre si. Quanto aos terços, o apical apresentou maior quantidade da smear em comparação com o terço médio (p< 0,01).Manual or rotary instrumentation techniques do not efficiently clean mesio-distal flattened root canals. This study evaluated, in vitro, smear layer removal of 40 mesio-distal flattened root canals after rotary instrumentation. The teeth were then divided into 4 groups: group 1: rotary instrumentation and 2.5% sodium hypochlorite used as irrigating solution; group 2: instrumented as group 1 and followed by Er: YAG laser irradiation (140mJ input/10Hz), withdrawn at 2mm/s from the apical to the cervical region touching the buccal walls the procedure was then repeated for the lingual wall); group 3: instrumented as group 1 and followed by Er: YAG laser irradiation (250mJinput/10Hz) withdrawn at 2mm/s from the apical to the cervical region touching the buccal walls the procedure was then repeated for the lingual wall) and group 4: instrumented as group 1 and alternated with 17% EDTA Teeth were split longitudinally and prepared for examination under scanning electron microscopy. Scores from 1 to 4 were given to the fotomicrographs by three independent evaluators, and these data was submitted to statistical analysis. The teeth where alternated 17% EDTA were used (group 4) showed less amount of smear layer, followed by the group irradiated with 250mJinput/10Hz (group 3), the group irradiated with 140mJ input/10Hz and the group where only sodium hypochlorite was used. The apical third presented more smear layer than the middle third (p<00.1).
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Anders, Stephanie. "Spätergebnisse in der Therapie der Besenreiservarikosis Nd-Yag Laser versus Hydroxypolyethoxydodecan." Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-51243.
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Forte, Paulo Manuel Figueiras. "Síntese e caracterização de nano emissores de YAG : Dy para LEDs." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12341.
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Mestrado em Engenharia FísicaEste trabalho teve como objetivo principal a utilização de uma técnica de síntese eficiente e de baixo custo para a produção de nano emissores de granada de ítrio e alumínio (YAG) dopado com iões trivalentes de disprósio (YAG:Dy). A técnica adotada foi a síntese por auto combustão em solução (SCS) com combinação de combustíveis. Numa primeira fase estudou-se a influência dos combustíveis (ureia, glicina e a combinação dos dois) na qualidade estrutural e ótica do material produzido, neste caso YAG dopado com térbio, com vista a identificar o método de produção mais eficaz. Estudou-se de seguida a influência da percentagem da dopagem de disprósio na qualidade dos materiais produzidos usando uma combinação de ureia e glicina em quantidades estequiométricas. Durante a síntese identificou-se que o processo dava origem a materiais com diferentes propriedades em função da sua localização no reator, pelo que foi igualmente realizado um estudo comparativo destes dois materiais e como as suas propriedades eram influenciadas por tratamentos térmicos pós-síntese. Também a influência do tipo de reator, forno ou placa de aquecimento, nas referidas propriedades foi estudada para os materiais produzidos. Foram utilizadas técnicas de difração de raios-X, e espectroscopia de Raman para caracterizar as estruturas produzidas e técnicas de espectroscopia de fotoluminescência para a caracterização ótica da emissão dos nano pós produzidos. Pretendeu-se com este estudo identificar as condições ótimas de síntese para o objetivo pretendido. Dos resultados obtidos pode-se afirmar que o uso combinado, em quantidades estequiométricas, de ureia e glicina pelo método de SCS permitiu a obtenção de pós de YAG, cujos tamanhos da cristalite variaram entre os 28 nm e os 42 nm. Também se observou a incorporação do disprósio, na sua forma trivalente, na rede cristalina do YAG, sendo que a sua emissão mais intensa se observa para dopagens de 2% de disprósio.
The main goal of this work is the use of an efficient and low cost synthesis technique to produce emissive nano powders of yttrium aluminum garnet (YAG) doped with dysprosium ions (YAG:Dy). The adopted technique was a variation of the solution synthesis combustion (SCS) with fuels combination. We start by studying the fuels influence (urea, glycine and a combination of both) on the structural and optic quality of the synthesized material, in this case YAG doped with terbium, to identify a more effective production method. The next step was study the influence of the dysprosium percentage in the produced materials quality using a combination of urea and glycine in stoichiometric quantities. During the synthesis was identified that process originate materials with different properties depending of their positions in the reactor. Therefore, a comparative study of this two materials was made and also how their properties were influenced by heat treatment after the synthesis. Also two different type of reactors were used, a furnace and a thermal plate, and their influence on the produced materials properties were studied. X-ray diffraction and Raman spectroscopy techniques were used to characterize the produced structures combined with photoluminescence techniques to optically characterize the produced nano-phosphors. With this study was possible to identify the best synthesis conditions in order to achieve the intended properties of the nano-phosphors. From the characterization results we identified the combined used of urea and glycine in stoichiometric quantities as the best option to obtain pure YAG phosphors by the SCS method. Crystallite sizes between 28 nm and 42 nm were obtained. Also the incorporation of the different percentages of dysprosium ions (in their trivalent form) into the YAG lattice was achieved. From the incorporation studies we identified the most intense emission was observed to 2% doping samples.
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Hasseler, Wolfgang Renold Theis Guido Franz Josef. "Effekte der Erbium : YAG Laser-Bestrahlung an der Synovialis des Pferdes /." [S.l.] : [s.n.], 2001. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Diss. med. vet. Bern, 2002.Diese Arbeit wird als Gemeinschaftsarbeit publiziert: Theis, G.F.J. und Hasseler, W.R. (2002) Effekte der Erbium: YAG Laser- und der Holmium: YAG-Laser-Bestrahlung an der Synovialis des Pferdes. Literaturverz.
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Bécquart, Jean-Philippe. "Le traitement par le laser nd-yag a titre palliatif et curatif de 80 tumeurs recto-coliques." Bordeaux 2, 1988. http://www.theses.fr/1988BOR25380.
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Meng-JungLi and 李孟蓉. "Influence of ionic mobility on the YAG transformation and investigation of the formation mechanism of hexagonal-YAP and YAG." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/62130031230533882009.
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碩士國立成功大學
資源工程學系碩博士班
98
Yttrium Aluminum garnet (YAG, Y3Al5O12) is a promising ceramic material which are largely used in optical applications. It is generally believed that the formation YAG phase via solid-state reaction is carried out by the diffusion of Al3+ ions into Y2O3 structure. Therefore, the formation of YAG under stoichiometric condition ([Y3+]/[Al3+] = 3/5) should depend on the ionic mobility of the used precursors. In the present work, the diffusional mobilities of Y3+ or Al3+ sources are modified by using different staring materials, either crystallized or amorphous precursors. In addition, NaCl is incorporated as a flux in order to further enhance the diffusion rate of the reactants. According to the experimental results, formation of YAG material is indeed carried out by the diffusion of Al3+ ions into Y2O3 structure even when the Y3+ ion exhibits a better mobility than Al3+ ions. For the samples prepared without NaCl, the phase transformation processes all follow the conventional pathway through firstly Y4Al2O9 (YAM), YAlO3 perovskite (YAP) and finally to stable YAG phase. However, the presence of NaCl flux gives a strong effect on the phase transformation behaviors for the sample prepared by using [Y2O3/ amorphous Al]. In this case YAM and YAP phases are never found in the system, nevertheless hexagonal-YAlO3 (YAH) is largely observed in a very short time of heat treatment that turns directly into YAG. According to TEM observations, the Y2O3 particles are apparently destroyed due to the accelerated diffusion of Al3+ ion into Y2O3 structure by the presence of NaCl flux and as a consequence generates the formation of YAH prior to YAM or YAP. Moreover, the as-formed YAH particles all exhibit similar sizes implying that they are formed by nucleation and growth controlled process. On the other hand, YAG phase is appeared directly without passing through intermediate phases if the precursors of Al and Y sources are both amorphous. According to the experimental results mentioned above, the phase transformation behaviors of YAG are found to dominate by the ionic mobility but also the atomic homogeneity of the using Y3+ ion or Al3+ sources.
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Lee, Jian Lung, and 李建龍. "Aanlysis of passively Q-Switch Lasers With Simultaneous Mode-Locking : Nd : YAG / Cr4+ : YAG Laser System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/75762314800730621803.
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碩士國立交通大學
電子物理系
90
We can obtain high peak power laser with absorber inside cavity. High peak power lasers are applied to distance measuring, radar, medical system and industry marker process. Increasing the length of cavity leads to narrower pulsewidth and higher peak power of pulse laser. A general recurrence is derived for the analysis of temporal shape of a single Q-switch envelope with mode-locked pulse trains. With the developed model, the mode-locked pulse and Q-switch pulse energy can be calculated. Excellent agreement was found between the present results and detailed theoretical computations.