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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Efeitos da radiação x em um composito odontologico

Terra, Etienne Romanelli 21 February 2005 (has links)
Orientador: Frab Norberto Boscolo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-04T04:17:51Z (GMT). No. of bitstreams: 1 Terra_EtienneRomanelli_M.pdf: 924097 bytes, checksum: 3d167bca45ac0474585a5d784fe9ec2a (MD5) Previous issue date: 2005 / Resumo: Como a maioria dos pacientes que se submetem à radioterapia na região de cabeça e pescoço possuem restaurações de compósitos na cavidade bucal, qualquer efeito interativo entre o feixe de radiação ionizante incidente e o material restaurador será clinicamente significativo, se as propriedades do material forem alteradas pela radiação. Desconhecendo-se os efeitos dos raios X, produzidos por um acelerador linear, no compósito odontológico FilteK Z250 (3M), foram realizados estudos para avaliar as possíveis alterações nas propriedades físicas, mecânicas e químicas deste compósito após a irradiação. Foram confeccionados 100 corpos-de-prova e mantidos armazenados durante todo o experimento a 37°C e 100% de umidade relativa do ar. O grupo 0 não irradiado foi composto por vinte corpos-de-prova, enquanto os demais corpos-de-prova foram aleatoriamente divididos em quatro grupos, conforme as doses de radiação X recebidas: 1, 2, 5 e 10Gy. Foram utilizados metade dos corpos-de-prova de cada um dos grupos para a análise de rugosidade de superfície e resistência à abrasão, e os demais, para a análise de dureza Knoop e espectrometria de Infravermelho com Transformações de Fourier. Os dados obtidos foram submetidos à análise de variância para medidas repetidas e teste de Tukey (a = 0,05). No período avaliado, houve um aumento estatisticamente significante na dureza Knoop superficial induzida pela irradiação de 10Gy de raios X, indicando uma polimerização adicional no compósito fotopolimerizado, porém, a resistência à abrasão e a rugosidade superficial do compósito Z250 não foram afetadas pelos raios X, quando o compósito foi irradiado até a dose de 10Gy. Os resultados obtidos por meio dos espectros de infravermelho, mostraram que em todas as doses avaliadas alguns grupos funcionais foram consumidos e novos grupos foram formados quando comparados com a amostra não irradiada. Assim, verificou-se que a irradiação (nas doses de 1, 2, 5 e 10Gy) durante o período avaliado não promoveu efeitos prejudiciais no compósito Z250, apesar das alterações no seu espectro químico / Abstract: Since most patients submitted to radiotherapy of the head and neck have composite restorations, any interactive effect between ionizing radiation and restorative material will be clinically significant if the material properties are altered by radiation. Due to the lack of knowledge on the effects of X rays produced by a linear accelerator on the dental composite Filtek Z250 (3M), this study was undertaken to evaluate the possible alterations in the physical, mechanical and chemical properties of this composite after irradiation. One hundred specimens were fabricated and stored at 37ºC and 100% relative humidity of air throughout the study. Group 0 was not irradiated and comprised twenty specimens, and the other specimens were randomly divided into four groups, according to the X-ray doses received: 1, 2, 5 and 10Gy. Half of the specimens of each group were used for analysis of surface roughness and abrasion resistance, and the others were submitted to the Knoop hardness test and Fourier Transform Infrared Spectrometry. Data were submitted to analysis of variance for repeated measurements and to the Tukey test (a = 0.05). In the study period, there was a statistically significant increase in the surface Knoop hardness induced by irradiation with 10Gy of X rays, indicating additional curing of the light-cured composite, yet the abrasion resistance and surface roughness of the composite Z250 were not affected by the X rays when the composite was irradiated with up to 10Gy. The results obtained by the infrared spectra demonstrated that, for all dosages evaluated, some functional groups are consumed and new groups are formed when compared to the non-irradiated sample. Thus, it was observed that irradiation (doses 1, 2, 5 and 10Gy) during the period evaluated did not yield any harmful effects on the composite Z250, despite the alterations in its chemical spectrum / Mestrado / Radiologia Odontologica / Mestre em Radiologia Odontológica
52

Diagnostika mostu poškozeného požárem / Diagnosis of the fire damaged bridge

Olejková, Sabina January 2019 (has links)
This thesis is about assessment of a bridge construction influenced by fire accident. The bridge is situated at the highway D46 beyond the town Držovice. Within this construction research, there will be mentioned diagnostic methods – A non- destructive method (Ultrasonic pulse method and hardness tests) and destructive methods (borehole and tear off tests). For find out in which way was the concrete of the bridge damaged and hurt while facing a high temperature of fire, there were taken samples, which were analyzed by physical and chemical test. We can analyze composition and microstructure of the concrete. The result of this tests will be evaluated, and the actions of a remediation will be suggested.
53

Longitudinal In Vitro Effects of Silver Diamine Fluoride on Early Enamel Caries Lesions / Longitudinal Effects of SDF on Early Enamel Caries Lesions

Thompson Alcorn, Alice-Anne January 2020 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Objective: This study aimed to evaluate surface microhardness changes in early, incipient, non-cavitated white-spot, enamel caries lesions treated with silver diamine fluoride (SDF) longitudinally. The utilization of silver nitrate and potassium fluoride test groups served as additional controls to assist in evaluating if the remineralization effects were due to the silver or fluoride component in SDF. Hypotheses: 1. SDF treatment will result in increased surface microhardness of early, incipient, non-cavitated white-spot, enamel caries lesions compared to all other tested interventions. 2. Specimen storage for 2-weeks in artificial saliva will result in greater surface rehardening in lesions treated with SDF compared to other tested interventions. Design: This laboratory study had 5 intervention groups (SDF, silver nitrate (AgNO3), potassium fluoride (KF), 5.0-percent sodium fluoride varnish (FV), deionized water (DI)) × 2-time intervals after intervention (immediate & delayed pH-cycling), resulting in 10 groups (n = 18). Early, incipient, non-cavitated white-spot, enamel caries lesions were created in bovine enamel and extent of demineralization was determined using Vickers surface microhardness (VHNlesion). Intervention treatments were applied. Half the specimens from each group underwent immediate 5-day pH-cycling and half were stored in an incubator with artificial saliva for two weeks before undergoing 5-day pH-cycling. After pH-cycling, lesion hardness was evaluated using VHNpost. Specimens were then exposed to a second demineralization challenge and lesion softening was evaluated using VHNsecdem. Surface rehardening was calculated: ΔVHN =VHNpost - VHNlesion. Surface softening was calculated: ΔVHNsecdem =VHNsecdem – VHNpost. Data was analyzed using two-way ANOVA. Results: Immediately cycled, SDF had significantly (p < .0001) greater remineralization than DI, AgNO3, and FV. All delayed cycling groups had significantly (p < .0001) greater remineralization than FV. Significantly greater remineralization was noted in delayed AgNO3 (p < .0001), DI (p = .0003), and FV (p = .0006) compared to immediately cycled. After the second demineralization challenge, FV had significantly less surface softening than AgNO3 (p = 0.0002), DI (p = 0.0003), KF (p = 0.0225), and SDF (p = 0.0388) intervention groups. No significant difference was found between the pH-cycle timings. Conclusion: Based on our findings, FV maybe better suitable than SDF to treat early, incipient, non-cavitated white-spot, enamel caries lesions. Longitudinally, SDF exhibited greater remineralization than both FV and DI groups, though not statistically significant. However, upon a second demineralization challenge, FV significantly outperformed SDF in preventing surface softening. / 2021-09-30
54

Ispitivanje mehaničkih i površinskih svojstava stomatoloških nanostrukturisanih kompozitnih materijala na bazi smola / Determination of mechanical and surface properties of dental resin-based nanocomposites

Lainović Tijana 08 October 2015 (has links)
<p>Uvođenje nanočestica u stomatolo&scaron;ke kompozitne materijale predstavlja poku&scaron;aj da se odgovori univerzalnim zahtevima za kvalitetom direktnog zubnog ispuna, i da se stvori materijal koji kombinuje visoku mehaničku otpornost sa dobrim estetskim karakteristikama i zadovoljavajućim kvalitetom poliranja. Cilj sprovedene studije je bio da se ispita uticaj nanočestica, i soft-start metode svetlosne indukcije polimerizacije na mehanička i povr&scaron;inska svojstva savremenih stomatolo&scaron;kih nanokompozita, dostupnih na trži&scaron;tu. Ispitana su četiri stomatolo&scaron;ka nanostrukturisana kompozitna materijala na bazi smola i jedan univerzalni mikrohibridni kompozit, kao referentni materijal (Filtek Z250, 3M ESPE). Kori&scaron;ćena su po dva reprezentativna materijala iz dve podgrupe nanokompozita: nanopunjenih (Filtek Ultimate Body, 3M ESPE i Filtek Ultimate Translucent, 3M ESPE) i nanohibridnih kompozita (Filtek Z550, 3M ESPE i Tetric EvoCeram, Ivoclar Vivadent - TEC). Uzorci su polimerizovani nakon svetlosne aktivacije polimerizacije, uz kori&scaron;ćenje dva svetlosna režima: konvencionalnog i soft start režima. Pritisna i zatezna čvrstoća (dobijena poprečnim sabijanjem valjka, engl. diametral tensile strength) testirane su na Univerzalnoj ma&scaron;ini, kidalici. Tvrdoća uzoraka merena je testom za određivanje tvrdoće po Vickersu. Povr&scaron;inska tekstura i parametri hrapavosti određeni su skeniranjem povr&scaron;ine mikroskopom atomskih sila. Uop&scaron;teno, TEC je pokazao najniže vrednosti pritisne i zatezne čvrstoće, i tvrdoće, i statistićki je značajno bio slabiji od drugih testiranih materijala kroz sve mehaničke testove. Suprotno, TEC je imao najniže vrednosti parametara hrapavosti među testiranim materijalima. Spoj prepolimerizovanog punioca i polimerne baze u ovom materijalu pokazao se kao njegova slaba tačka. Navedeni materijal je iz tog razloga pokazao značajno slabiju otpornost od ostalih na razvijene napone izazvane dejstvom mehaničkih sila. Čestice nanodimenzija u sastavu stomatolo&scaron;kih polimernih kompozita, samostalno, nisu imale značajan uticaj na pobolj&scaron;anje mehaničkih i povr&scaron;inskih svojstava testiranih kompozita. Zaključeno je i da se procentualna zastupljenost neorganskih čestica u polimernoj bazi ne može smatrati apsolutnim kriterijumom kvaliteta kompozita, u pogledu njihovih mehaničkih svojstava. Samo srodni materijali, izrađeni istim tehnolo&scaron;kim postupkom, koji imaju veoma sličan ili isti hemijski sastav, pokazali su se kao mehanički superiorniji ukoliko su sadržali veći procenat neorganske komponente u svom sastavu. Nano prefiks u nazivu klase materijala ne garantuje sigurnu prednost stomatolo&scaron;kih nanokompozita nad univerzalnim mikrohibridnim kompozitima.</p> / <p>The introduction of nanoparticles in dental composite materials was an attempt to respond to the universal quality requirements for a direct dental restoration, and to create a material that meets the needs of high mechanical resistance, good aesthetic characteristics and surface properties of tooth restoratives. The aim of this study was to investigate the effect of nanoparticles in materials composition, and the soft start photoactivation method on the mechanical and surface properties of contemporary dental nanocomposites, available in the market. Four dental resin based nanostructured composites were tested along with a universal microhybrid one, as reference material (Filtek Z250, 3M ESPE). Two representative materials from the two classification subgroups were tested, nanofilled (Filtek Ultimate Body, 3M ESPE and Filtek Ultimate Translucent, 3M ESPE) and nanohybrid composites (Filtek Z550, 3M ESPE and Tetric EvoCeram, Ivoclar Vivadent, TEC). Polymerization of the samples was light activated using two light modes: conventional and soft start. Compressive and diametral tensile strength were tested on the Universal testing machine. The Vickers hardness was also determined. Surface texture and roughness parameters were examined by atomic force microscopy. Generally, TEC showed the lowest values of compression, tensile strength and hardness, and was statistically different from the other tested materials throughout all mechanical tests. In contrast, TEC had the lowest values of roughness parameters among the tested materials. In this material, contact zone of prepolimeryzed filler and polymer matrix appeared to be a weak point. For this reason, this material showed significantly lower resistance than the others on mechanically developed stresses. Nanosized particles within the dental polymer composites, individually, did not have a significant influence on improving the mechanical and surface properties of tested composites. It is concluded that the inorganic volume fraction in composites cannot be considered as an absolute criterion of their quality, regarding their mechanical properties. Only similar materials, made using the same technological process, which have very similar or the same chemical composition, and similar technological method of synthesis and optimization of organic and inorganic components, showed improved mechanical strength, if they contained a higher percentage of inorganic components in their composition. Nano prefix in the name of material&rsquo;s class does not guarantee the pure advantage of dental nanocomposites in comparison with the universal microhybrid composites.</p>
55

Efeito da irrigação prévia na adesão de cimentos resinosos autoadesivos ao canal radicular na cimentação de pinos de fibra de vidro / Effect of previous irrigation on the adhesion of self-adhesive resin cements to the root canal in the cementation of glass fiber posts

Jitumori , Renata Terumi 21 February 2018 (has links)
Submitted by Eunice Novais (enovais@uepg.br) on 2018-07-24T14:32:21Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) RENATA TERUMI JITUMORI.pdf: 3093609 bytes, checksum: 92de6bf22e06953ec3a932faaf478f71 (MD5) / Made available in DSpace on 2018-07-24T14:32:21Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) RENATA TERUMI JITUMORI.pdf: 3093609 bytes, checksum: 92de6bf22e06953ec3a932faaf478f71 (MD5) Previous issue date: 2018-02-21 / Avaliou-se o efeito da irrigação prévia na adesão de cimentos resinosos autoadesivos ao canal radicular na cimentação de pinos de fibra de vidro (PFV). Foram utilizados 120 dentes permanentes unirradiculares, os quais tiveram suas coroas removidas e suas raízes tratadas endodonticamente. Após uma semana, foi realizado o preparo padronizado dos condutos para posterior cimentação dos PFV. Nesse momento, as raízes foram divididas aleatoriamente em dez grupos, de acordo com a combinação dos seguintes fatores: cimento resinoso autoadesivo – RelyX U200 (3M ESPE) e Multilink Speed (Ivoclar Vivadent), e agente irrigante aplicado previamente à cimentação dos PFV – água destilada (AD), NaOCl 2,5% (Na), EDTA 17% (ED), ácido poliacrílico 26% (AP) e associação EDTA 17% + NaOCl 2,5% (EN). Duas raízes de cada agente irrigante foram utilizadas para avaliação do grau de desobliteração dos túbulos dentinários (DeTd) por microscopia eletrônica de varredura (MEV). Após a cimentação dos PFV, sete raízes por grupo foram avaliadas em resistência de união (RU) pelo teste de push-out, quatro em nanoinfiltração (NI) por MEV e microdureza Vickers (VHN); para esse propósito cada raiz foi seccionada transversalmente em seis fatias. Os dados obtidos da DeTd foram submetidos a Kruskall Wallis e Student-Newman-Keuls (α=0,05) e dos testes de RU, NI e VHN a ANOVA dois fatores e Tukey (α=0,05). Na avaliação da DeTd, os agentes que promoveram maior abertura dos tubúlos dentinários foram ED, AP e EN. Para o cimento RelyX U200, o Na, AD e ED obtiveram os maiores valores de RU e VHN; enquanto que para o Multilink Speed esses valores foram superiores no grupo irrigado com AD. Para ambos os cimentos, o AP apresentou valores inferiores e a associação EN valores intermediários de RU e VHN. Não houve diferença estatística significante nos resultados de NI (p>0,05). Pode-se concluir que para cada agente cimentante deve haver um protocolo de irrigação prévia ideal na cimentação de pinos de fibra de vidro ao canal radicular. / It was evaluated the effect of previous irrigation on the adhesion of on the adhesion of self-adhesive resin cements to the root canal in the cementation of glass fiber posts. A total of 120 unirradicular permanent teeth were used, which had their crowns removed and their roots treated endodontically. After one week, the standard preparation of the post space was made for the cementation of the GFP. At this time, the roots were randomly divided into ten groups, according to the combination of the following factors: self-adhesive resin cement - RelyX U200 (3M ESPE) and Multilink Speed (Ivoclar Vivadent), and irrigating agent applied prior to GFP cementation - distilled water (DW), 2.5% NaOCl (Na), 17% EDTA (ED), 26% polyacrylic acid (PA) and 17% EDTA followed by 2.5% NaOCl (EN). Two roots of each irrigating agent were used for evaluation the degree of open dentinal tubules (ODeT) by scanning electron microscopy (SEM). After the cementation of the GFP, seven roots per group were evaluated in bond strength (BS) by the push-out test, four in nanoleakage (NL) by SEM and in Vickers microhardness (VHN); for this propose each root was sectioned transversely into six slices. The data obtained from ODeT were submitted to Kruskall Wallis and Student-Newman-Keuls (α=0.05) and from the tests of BS, NL and VHN to ANOVA two-way and Tukey (α=0.05). In the evaluation of the ODeT, the agents that promoted greater opening of the dentin tubules were ED, PA and EN. For RelyX U200 cement, the Na, DW and ED obtained the highest values of BS and VHN; while for Multilink Speed these values were higher in the group irrigated with DW. For both cements, the PA presented lower values and the association EN intermediate values of BS and VHN. There was no statistically significant difference in NL results (p>0.05). It can be concluded that for each cementing agent there must be an optimal prior irrigation protocol for the cementation of glass fiber posts to the root canal.
56

Síntese e caracterização de revestimentos protetores de ZrN/TiN sobre o biomaterial Nitinol obtidos por tratamento duplex.

Bernardi, Juliane Carla 08 July 2011 (has links)
O presente trabalho apresenta um estudo do tratamento duplex para o biomaterial Nitinol (NiTi). Este tratamento consiste em nitretação a plasma para a formação do nitreto de titânio (TiN), seguido de deposição de um filme fino de nitreto de zircônio (ZrN) sobre a superfície nitretada. O estudo das fases cristalinas presentes no sistema foi realizado pela técnica de difração de raios X (DRX). A morfologia e espessura da camada nitretada e do filme fino depositado foram avaliadas por microscopia eletrônica de varredura (MEV). As propriedades mecânicas foram estudadas mediante ensaios de nanoindentação. Para avaliar a resistência à corrosão foram realizados testes de polarização potenciodinâmica em solução de saliva artificial. Os resultados mostram que a temperatura de nitretação tem forte influência na formação do TiN na superfície do substrato. O filme de ZrN depositado sobre as amostras nitretadas apresenta propriedades de dureza e resistência à corrosão que dependem da temperatura de nitretação, mesmo tendo sido depositados sem variação de temperatura. Esse comportamento sugere que os filmes são influenciados pela condição inicial da superfície antes da deposição. Os melhores resultados em termos de dureza e resistência à corrosão foram obtidos nas amostras tratadas em temperaturas mais elevadas. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-05T18:07:33Z No. of bitstreams: 1 Dissertacao Juliane Carla Bernardi.pdf: 2940702 bytes, checksum: 376b73745f740260fc19e7a6e8b5d900 (MD5) / Made available in DSpace on 2014-06-05T18:07:33Z (GMT). No. of bitstreams: 1 Dissertacao Juliane Carla Bernardi.pdf: 2940702 bytes, checksum: 376b73745f740260fc19e7a6e8b5d900 (MD5) / The present work aims to study about duplex treatment on the biomaterial Nitinol (NiTi). This treatment consists in titanium nitride (TiN) formed by plasma nitration, followed by zirconium nitride (ZrN) thin film deposition upon the nitrated surface. The study of crystalline phases present in the system was performed by X-ray diffraction technique (XRD). The morphology and thickness of the nitrated layer and thin film were evaluated by scanning electron microscopy (SEM). The mechanical properties were studied by nanoindentation analysis. In order to evaluate corrosive resistance tests of potenciodynamic polarization were performed in solution of saliva artificial. Results demonstrate that nitration temperature has a strong influence in the formation TiN on the substrate surface. The ZrN film depositated upon nitrated samples present hardness and corrosive resistance properties that depend on nitration temperature, even though ZrN films were depositated without temperature variation. This behaviour suggests that films are influenced by the initial surface condition before depositon. The best results in terms of hardness and corrosive resistance were obtained in samples treated at higher temperatures.
57

Síntese e caracterização de revestimentos protetores de ZrN/TiN sobre o biomaterial Nitinol obtidos por tratamento duplex.

Bernardi, Juliane Carla 08 July 2011 (has links)
O presente trabalho apresenta um estudo do tratamento duplex para o biomaterial Nitinol (NiTi). Este tratamento consiste em nitretação a plasma para a formação do nitreto de titânio (TiN), seguido de deposição de um filme fino de nitreto de zircônio (ZrN) sobre a superfície nitretada. O estudo das fases cristalinas presentes no sistema foi realizado pela técnica de difração de raios X (DRX). A morfologia e espessura da camada nitretada e do filme fino depositado foram avaliadas por microscopia eletrônica de varredura (MEV). As propriedades mecânicas foram estudadas mediante ensaios de nanoindentação. Para avaliar a resistência à corrosão foram realizados testes de polarização potenciodinâmica em solução de saliva artificial. Os resultados mostram que a temperatura de nitretação tem forte influência na formação do TiN na superfície do substrato. O filme de ZrN depositado sobre as amostras nitretadas apresenta propriedades de dureza e resistência à corrosão que dependem da temperatura de nitretação, mesmo tendo sido depositados sem variação de temperatura. Esse comportamento sugere que os filmes são influenciados pela condição inicial da superfície antes da deposição. Os melhores resultados em termos de dureza e resistência à corrosão foram obtidos nas amostras tratadas em temperaturas mais elevadas. / The present work aims to study about duplex treatment on the biomaterial Nitinol (NiTi). This treatment consists in titanium nitride (TiN) formed by plasma nitration, followed by zirconium nitride (ZrN) thin film deposition upon the nitrated surface. The study of crystalline phases present in the system was performed by X-ray diffraction technique (XRD). The morphology and thickness of the nitrated layer and thin film were evaluated by scanning electron microscopy (SEM). The mechanical properties were studied by nanoindentation analysis. In order to evaluate corrosive resistance tests of potenciodynamic polarization were performed in solution of saliva artificial. Results demonstrate that nitration temperature has a strong influence in the formation TiN on the substrate surface. The ZrN film depositated upon nitrated samples present hardness and corrosive resistance properties that depend on nitration temperature, even though ZrN films were depositated without temperature variation. This behaviour suggests that films are influenced by the initial surface condition before depositon. The best results in terms of hardness and corrosive resistance were obtained in samples treated at higher temperatures.
58

Průzkum a hodnocení železobetonové mostní konstrukce / Survey and assessment of reinforced concrete bridge construction

Šnédar, Jaroslav January 2020 (has links)
The aim of this thesis is to evaluate the real condition of reinforced concrete beam bridge located in Brno Jundrov. In order to evaluate this condition, there was made the main bridge inspection. Subsequently, a number of diagnostic methods were used, such as hardness tests, concrete stress strenght, ultrasonic pulse method, including their evaluation. In terms of the main inspection, the condition of construction of the bridge was evaluated as V - bad. We found out that the concrete from which the bridge is built of is in very good condition. The problem, however, is the condition of the reinforcement located on the bridge. Based on its condition there must be expected lifespan within the next 5-10 years.

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