Made available in DSpace on 2014-12-17T14:07:21Z (GMT). No. of bitstreams: 1 JeanneHCR.pdf: 2470228 bytes, checksum: 64b0abbe75bda944c8a21ce90a9f572b (MD5) Previous issue date: 2006-09-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Nowadays, composite resins are the direct restorative materials more important in dental clinical performance, due to their versatility and aesthetic excellence. Bis-GMA (2,2-bis[4(2-hydroxy-3-metacryloxypropoxy)phenil]propane) is the base monomer more frequently used in restorative composite resins. However, this monomer presents some disadvantages, such as high viscosity and two aromatic rings in its structure that can promote allergic reactions to the humans. In this work, the main purpose was to synthesize new monomers from glycidyl methacrylate to use in dental restorative materials. Structural characterization of the monomers was carried out through FTIR and NMR 1H, and eight composites were produced from the new monomers, by addition of silane-treated alumino silicate particles (inorganic filler) and a photocuring system (camphorquinone and ethyl 4-dimethylaminebenzoate). The composites were analyzed by environmental scanning electronic microscopy and the water sorption and solubility, compressive strength and elastic modulus were determined. A commercial composite resin [Z100 (3M)] was used to comparison effect. The new composites presented general characteristics similar to the commercial ones; however, they didn t present the properties expected. This behavior was attributed to the lower degree of monomer reaction and to the granulometry and size distribution of the mineral filler in the polymeric matrix / Atualmente, as resinas compostas constituem-se no material restaurador direto mais utilizado nas interven??es da cl?nica odontol?gica, dada a sua versatilidade e excel?ncia est?tica. O mon?mero mais freq?entemente usado na matriz polim?rica dessas resinas ? o Bis-GMA (2,2-bis[4(2-hidr?xi-3-metacriloiloxipropoxi)fenil]propano). No entanto, esse mon?mero apresenta algumas desvantagens, tais como elevada viscosidade e a presen?a de dois an?is arom?ticos em sua estrutura que podem causar rea??es al?rgicas ao organismo humano. Dessa forma, o objetivo principal deste trabalho foi sintetizar, a partir do metacrilato de glicidila, novos mon?meros para serem utilizados como componentes de poss?veis materiais restauradores dentais. A estrutura qu?mica dos mon?meros obtidos foi caracterizada pelas t?cnicas espectrosc?picas FTIR e RMN 1H, e oito comp?sitos foram preparados a partir dos novos mon?meros e part?culas silanizadas de silicato de alum?nio (carga inorg?nica), utilizando um sistema fotoativador/iniciador composto por canforoquinona e 4-dimetil amina benzoato de etila. Os comp?sitos foram analisados por microscopia eletr?nica de varredura ambiental e avaliados quanto ? sor??o e solubilidade em ?gua, resist?ncia ? compress?o e m?dulo de elasticidade. Para efeito de compara??o, utilizou-se a resina composta comercial Z100 (3M). Os novos comp?sitos preparados apresentaram caracter?sticas gerais semelhantes ?s resinas comerciais, entretanto, n?o se comportaram como esperado em rela??o ?s propriedades estudadas, o que foi atribu?do ao menor grau de rea??o dos mon?meros e ? granulometria e distribui??o da carga mineral na matriz polim?rica

Philosophiae Doctor - PhD / In the presented work, immunosensors for detection of Aflatoxin B1 based on different immobilization platforms were studied. Synthesis of an electroactive hydrogel was also carried out. Aflatoxins are a group of mycotoxins that have deleterious effects on humans and are produced during fungal infection of plants or plant products. Electrochemical immunosensor for the determination of Aflatoxin B1 (AFB1) was developed with anti-aflatoxin B1 antibody immobilized on Pt electrodes modified with polyaniline (PANi) and polystyrene sulphonic acid (PSSA). Impedimetric analysis shows that the electron transfer resistances of Pt/PANi-PSSA electrode, Pt/PANi-PSSA/AFB1-Ab immunosensor and Pt/PANi-PSSA/AFB1-Ab incubated in BSA were 0.458, 720 and 1066 kΩ, respectively. These results indicate that electrochemical impedance spectroscopy (EIS) is a suitable method for monitoring the change in electron-transfer resistance associated with the immobilization of the antibody. Modelling of EIS data gave equivalent circuits which showed that the electron transfer resistance increased from 0.458 kΩ for Pt/PANi-PSSA electrode to 1066 kΩ for Pt/PANi-PSSA/AFB1-Ab immunosensor, indicating that immobilization of the antibody and incubation in BSA introduced an electron transfer barrier. The AFB1 immunosensor had a detection limit of 0.1 mg/L and a sensitivity of 869.6 kΩL/mg. / South Africa

Philosophiae Doctor - PhD / In the presented work, immunosensors for detection of Aflatoxin B1 based on different immobilization platforms were studied. Synthesis of an electroactive hydrogel was also carried out. Aflatoxins are a group of mycotoxins that have deleterious effects on humans and are produced during fungal infection of plants or plant products. Electrochemical immunosensor for the determination of Aflatoxin B1 (AFB1) was developed with anti-aflatoxin B1 antibody immobilized on Pt electrodes modified with polyaniline (PANi) and polystyrene sulphonic acid (PSSA). Impedimetric analysis shows that the electron transfer resistances of Pt/PANi-PSSA electrode, Pt/PANi-PSSA/AFB1-Ab immunosensor and Pt/PANi- PSSA/AFB1-Ab incubated in BSA were 0.458, 720 and 1066 kΩ, respectively. These results indicate that electrochemical impedance spectroscopy (EIS) is a suitable method for monitoring the change in electron-transfer resistance associated with the immobilization of the antibody. Modelling of EIS data gave equivalent circuits which showed that the electron transfer resistance increased from 0.458 kΩ for Pt/PANi-PSSA electrode to 1066 kΩ for Pt/PANi- PSSA/AFB1-Ab immunosensor, indicating that immobilization of the antibody and incubation in BSA introduced an electron transfer barrier. The AFB1 immunosensor had a detection limit of 0.1 mg/L and a sensitivity of 869.6 k ΩL/mg. In the second platform an immunosensor based on gold nanoparticles (AuNP) and polythionine-modified glassy carbon electrode (GCE) for the determination of aflatoxin B1 (AFB1) was developed. Aflatoxin B1-BSA conjugate was immobilised on the modified GCE. Horseradish peroxidase (HRP) or Bovine serum albumin (BSA) were used to block sites against non-specific binding of the AFB1- conjugate with other compounds such as the salts used in preparing the buffer when the antibody interacts with the AFB1 conjugate and free AFB1. Competition reaction was allowed to take place between the free AFB1 and AFB1-conjugate for the binding sites of the anti-aflatoxin B1 antibody. Cyclic voltammetry (CV) was employed to characterize the electrochemical properties of the modified process. The peak separation of the immunosensor (ΔEp) was 62 mV indicating a quasi reversible process. Differential pulse voltammetry (DPV) was used to monitor the analytical signal. The response decreased with an increase in AFB1 concentration in the range of 0.6-2.4 ng/mL with a limit of detection of 0.07 and 0.16 ng/mL for HRP and BSA blocked immunosensors respectively. Significantly the low detection limit of 0.07 ng/mL is within the limits set by worl health organization (WHO) for AFB1 and its derivatives which is 2 ng/mL The proposed method eliminates the use of secondary antibody enzymatic labels. Synthesis and characterization of (p-(HEMA)-polyaniline hydrogels were investigated. The hydrogels were synthesized using: 2-Hydroxyeththyl methacrylate (HEMA), N-Tris (hydroxymethyl) methyl] acrylamide, 3- Sulfopropyl methacrylate potassium salt, Tetraethylene glycol diacrylate, Poly-(2- hydroxyethyl methacrylate), 2, 2-Dimethoxy-2-phenylacetophenone and aniline by UV irradiation. Two sets of the hydrogels were prepared using water / 1, 3, 3, 3-(tetramethyl butyl phenyl polyethylene glycol [Triton X-100] and water / ethylene glycol as the solvent. Scanning electron microscopy (SEM) revealed a more uniform pore size when Triton X 100 (TX-100 HG) was used as compared to ethylene glycol (EG-HG). Thermogravimetric analysis (TGA) showed that both hydrogels were stable up to 270 oC. Fourier transform-Infra red (FTIR) spectrum confirmed the incorporation of polyaniline (PANi) and HEMA in the composite. Electrochemical properties of the hydrogels evaluated using Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS) demonstrated the electroactivity and conductivity.

Sub-surface modification using a frequency doubled Ti: Sapphire femtosecond (fs) laser at 1kHz repetition rate, producing 100-fs pulse duration at 400nm, is studied in order to fabricate optical components within non-photosensitised polymethyl methacrylate (PMMA). This thesis explores the feasibility of producing three-dimensional optical devices in bulk polymers and polymer optical fibre (POF) using fs laser direct-writing techniques. For effective and optimal structuring, the laser writing parameters and focusing conditions, such as focusing depth, translation speed, and accumulated fluence are investigated by means of photo-modification thresholds; structural changes in dimensions and morphologies; and the magnitude of the refractive index modulation. The highest refractive index change is 3.2x10^(-3) achieved by using a dry (non-immersion) 0.45-NA objective for a single laser scan. Variations in damage threshold with focusing depths are attributed to a combination of material absorption or surface scattering of light due to contamination or surface imperfections, as well as oxygen diffusion and spherical aberration. Distortion of the laser-induced feature size and shape due to spherical aberrations is controlled and compensated by adjusting the laser power near the damage threshold. Permanent refractive index structures with cross-sectional dimensions of 2μm by 0.9μm and 3μm by 1.4μm are demonstrated at depths of 300μm and 500μm below the surface, resulting in the axial/ lateral ratio of 2.2 and 2.1, respectively. A novel phenomenon relevant to effects of translation speed on the fs laser modification is observed for the first time. As translation speeds reduce from 1.2 to 0.6mm/s, the optical damage threshold power decreases by 6μW, whilst other writing conditions remain constant. However, the damage threshold increases by 74μW with decreasing speeds from 0.6 to 0.35mm/s. This significant increase in threshold power enables inscription of refractive index gratings <5μm below the surface, because irradiation on the surface or near the surface initiates ablation rather than refractive index changes, and this forms a limit for writing useful structures. Compensating for this limit by using appropriate writing parameters highlights the potential of fabricating three-dimensional integrated optical circuits in thin (100μm) polymer substrates. Finally, highly localised fabrication of long period gratings into step-index single mode polymer fibres is demonstrated by removing distortion effects due to the curved surface. The distortion is compensated by sandwiching the fibre with two flat PMMA sheets, between which index-matching oil (n=1.5) is injected. This arrangement enables precise laser micro-structuring with flat interfaces and continuous inner material. The first demonstration of a 250-μm-period fibre grating, resulting in attenuation bands in the visible spectral region at 613, 633, 728, 816, 853, 877 and 900nm, is presented.

Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-05-03T17:14:13Z No. of bitstreams: 3 Tese - Amanda Vessoni Barbosa Kasuya - 2017-1-50.pdf: 15013683 bytes, checksum: f8924a9fa740c813552a7c3316dba183 (MD5) Tese - Amanda Vessoni Barbosa Kasuya - 2017-51-111.pdf: 15359599 bytes, checksum: ea14f282d1609854707110f304682486 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Rejected by Luciana Ferreira (lucgeral@gmail.com), reason: olhe no guia a forma de nomear arquivos divididos on 2017-05-04T11:04:01Z (GMT) / Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-05-04T17:04:01Z No. of bitstreams: 3 Tese - Amanda Vessoni Barbosa Kasuya - 2017- Parte 1.pdf: 15013683 bytes, checksum: f8924a9fa740c813552a7c3316dba183 (MD5) Tese - Amanda Vessoni Barbosa Kasuya - 2017- Parte 2.pdf: 15359599 bytes, checksum: ea14f282d1609854707110f304682486 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Rejected by Luciana Ferreira (lucgeral@gmail.com), reason: No guia está registrado: - Quando o arquivo tiver que ser dividido, por ser grande, cada um deve ser renomeado da mesma forma, adicionando a indicação da parte, entre parênteses, no final. Exemplos: “Tese - João Alves da Silva - 2015 (1)”, “Tese - João Alves da Silva - 2015 (2)”. on 2017-05-05T12:44:32Z (GMT) / Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-05-05T16:53:52Z No. of bitstreams: 3 Tese - Amanda Vessoni Barbosa Kasuya - 2017- Parte 1.pdf: 15013683 bytes, checksum: f8924a9fa740c813552a7c3316dba183 (MD5) Tese - Amanda Vessoni Barbosa Kasuya - 2017- Parte 2.pdf: 15359599 bytes, checksum: ea14f282d1609854707110f304682486 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Rejected by Erika Demachki (erikademachki@gmail.com), reason: on 2017-05-05T17:13:14Z (GMT) / Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-05-05T17:15:42Z No. of bitstreams: 3 Tese - Amanda Vessoni Barbosa Kasuya - 2017 (1).pdf: 15013683 bytes, checksum: f8924a9fa740c813552a7c3316dba183 (MD5) Tese - Amanda Vessoni Barbosa Kasuya - 2017 (2).pdf: 15359599 bytes, checksum: ea14f282d1609854707110f304682486 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-05-08T15:51:39Z (GMT) No. of bitstreams: 3 Tese - Amanda Vessoni Barbosa Kasuya - 2017 (1).pdf: 15013683 bytes, checksum: f8924a9fa740c813552a7c3316dba183 (MD5) Tese - Amanda Vessoni Barbosa Kasuya - 2017 (2).pdf: 15359599 bytes, checksum: ea14f282d1609854707110f304682486 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-05-08T15:51:39Z (GMT). No. of bitstreams: 3 Tese - Amanda Vessoni Barbosa Kasuya - 2017 (1).pdf: 15013683 bytes, checksum: f8924a9fa740c813552a7c3316dba183 (MD5) Tese - Amanda Vessoni Barbosa Kasuya - 2017 (2).pdf: 15359599 bytes, checksum: ea14f282d1609854707110f304682486 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-03-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objectives of this work were to evaluate the stress distribution (SD), fracture resistance (RF), adhesive strength (AS) and their respective fracture patterns of weekeaned bovine roots, rehabilitated with customized pins with different resinous materials. In addition, the objective of this study was to evaluate the polymerization depth of the resinous materials by Knoop microhardness method (MH). Eight experimental groups were established (n = 10 for FR and AS; n = 5 for MH), with the factor under study: 1. The post type (industrialized glass fiber post relined (I) and personalized post (P), 2. the relining material only for industrialized glass fiber post (experimental composite (e) and composite resin (R)); 3. the material used only for personalized post (experimental composite (e) and bulk fill resin (b), and 4. the amount of remaining dentin (root embrittlement inner wear, in lengths of 5 mm or 10 mm). One hundred and forty bovine roots of similar size were selected and restored according to the group to which they belonged. For FR, Pperiodontal and alveolar bone were simulated and the specimens were placed in an Instron 5965 machine at a 135 ° angle to the long axis and loaded at a constant velocity of 0.5 mm/min in compression until the fracture. The fracture pattern was classified as: F1- crown; F2- root; F3- crown/root; F4- fracture with displacement of the crown/post. For AS, the specimens were sectioned in slices of 1 mm perpendicular to their long axis. Each specimen was placed in a test machine to received the load in the apical-coronal direction, at a constant velocity of 0.5mm / min, pushing the pin through the largest side of the sample until fracture. The fracture pattern was classified as: F1- cohesive of the pin and/or reline material; F2- cohesive of dentin; F3- adhesive of pin/reline material; F4 - Adhesive bonding cement/ eline material and F5 - mixed. For MH, the specimens were sectioned parallel to their long axis. The tests were performed with a Knoop penetrator under a static charge of 50 grams per 10 seconds. MH was calculated as the average value for each third. Finally, the finite element method was used to analyze the DT. 3D virtual models representative of each experimental group were created and analyzed under von Mises equivalent stresses criterion, simulating loading of 100N at a 45o angle with the long axis. The experimental composite proved to be an alternative for the rehabilitation of weakened roots when used to create personalized posts or when used as a relining material, with FR values similar to the traditional technique, but with more favorable stress distributions. Moreover, it presented excellent adhesive strength to the dentin structure, being comparable to conventional composite resin and bulk fill resin. The bulk fill resin resulted in low values of fracture resistance associated with the fracture and displacement of post/crown. Lower microhardness values were observed in the apical third for bulk fill resin. / Os objetivos deste trabalho foram avaliar a distribuição de tensões (DT), resistência à fratura (RF), resistência adesiva (RA) e seus respectivos padrões de fratura de raízes bovinas fragilizadas, reabilitadas com pinos personalizados com diferentes materiais resinosos. Além disso, objetivou-se avaliar a profundidade de polimerização dos materiais resinosos por meio do método de microdureza Knoop (MD). Oito grupos experimentais foram criados (n=10 para RF e RA; n=5 para MD), tendo como fator em estudo: 1. o tipo de pino utilizado (pino de fibra de vidro industrializado reembasado (I) e pino personalizado (P)); 2. o material de reembasamento apenas para os pinos industrializados (compósito experimental (e) e resina composta (r)); 3. o material utilizado para confecção apenas dos pinos personalizados (compósito experimental (e) e resina bulk fill (b)); e 4. a quantidade de dentina remanescente (fragilização radicular por desgaste interno nos comprimentos de 5 mm ou 10 mm). Cento e quarenta raízes bovinas com dimensões semelhantes foram selecionadas e restauradas de acordo com o grupo ao qual pertenciam. Para RF, ligamento periodontal e osso alveolar foram simulados e os espécimes posicionados em máquina Instron 5965, em um ângulo de 135° em relação ao longo eixo do dente de modo que recebessem carregamento à velocidade constante de 0,5mm/min em compressão até a fratura. Em seguida, o padrão de fratura foi classificado em: F1- coroa; F2- raiz; F3- coroa/raiz; F4- fratura com deslocamento do conjunto coroa/pino. Para RA, os espécimes foram seccionados em fatias 1 mm perpendicularmente ao seu longo eixo. Cada espécime foi posicionado em máquina de ensaio de modo que recebessem a carga no sentido apical-coronal, à velocidade constante de 0,5mm/min, empurrando o pino através do maior lado da amostra até a fratura. O padrão de fratura foi classificado em: F1 - coesiva do pino e/ou material de reembasamento; F2 - coesiva da dentina; F3 - adesiva pino/material de reembasmento; F4 - adesiva material de reembasamento/cimento e F5 – mista. Para MD, os espécimes foram seccionados paralelamente ao seu longo eixo. Os testes foram realizados com um penetrador Knoop sob uma carga estática de 50 gramas por 10 segundos. MD foi calculada como o valor médio para cada terço. E por fim, o método de elementos finitos foi empregado para analisar a DT. Modelos virtuais 3D representativos de cada grupo experimental foram criados e analisados sob critério de tensões equivalentes de von Mises, simulando carregamento de 100N em um ângulo de 45o com o longo eixo. O compósito experimental demostrou ser uma alternativa para a reabilitação de raízes fragilizadas quando utilizado para criar pinos personalizados ou quando utilizado como material de reembasamento de pinos, com valores de resistência à fratura semelhantes à técnica tradicional porém, com distribuição de tensões mais favoráveis. Além disso, apresentou excelente resistência adesiva à estrutura dentinária, sendo comparável à resina composta convencional e à resina bulk fill. Já a resina bulk fill resultou em baixos valores de resistência à fratura associado ao deslocamento do conjunto pino/coroa protética. Valores de microdureza inferiores foram observados no terço apical para a bulk fill.

Este estudo teve o objetivo de avaliar in vitro a influência da alteração dimensional de resinas acrílicas para base de prótese total submetidas a diferentes formas de processamento sobre a posição da cabeça da mandíbula, buscando estabelecer uma possível relação com a etiologia das disfunções crânio-mandibulares nos pacientes usuários desse tipo de prótese. Foram duas etapas: a primeira parte enfocou o papel do tipo de prensa (Getom ou de cozimento) e da força de prensagem para fechamento da mufla (1000 ou 1500 kgf) utilizados no processamento de duas resinas: Lucitone 550 e QC–20 e somente da força de prensagem para a resina Acron MC. Já a segunda parte do estudo teve o intuito de avaliar a influência dos ciclos de polimerização curtos e longos na alteração dimensional de cinco resinas: as mesmas três da primeira parte, além da Clássico e Ondacryl. As próteses superiores acrilizadas foram remontadas em articulador totalmente ajustável, tendo como referência a posição de máxima intercuspidação (MIC). Nessa posição de maior estabilidade oclusal, foi vazado gesso tipo IV no espaço entre as esferas condilares do articulador e as paredes dos estojos condilares. Após a cristalização, esses corpos-de-prova de gesso foram removidos do estojo condilar e suas dimensões medidas e submetidas à análise estatística por meio de um modelo de análise de variância com medidas repetidas que permitiu concluir que houve variações na posição da “cabeça da mandíbula” em 625 das 630 medidas efetuadas; as médias de movimentação condilar variaram de 0,118 (DP = 0,0968) a 1,956 mm (DP = 0,414) e ocorreram principalmente no sentido posterior do lado esquerdo; na maioria dos casos em que a força de prensagem agiu como fator devariação, os deslocamentos obtidos com 1500 kgf foram menores do que aqueles obtidos com 1000 kgf; nos casos em que o tipo de prensa agiu como fator de variação, ora os menores deslocamentos foram obtidos com a prensa de cozimento, ora com a Getom; o ciclo empregado na polimerização não influenciou significativamente na estabilidade dimensional das próteses totais e a única diferença encontrada envolveu a resina Clássico, que levou aos maiores deslocamentos no sentido posterior do lado esquerdo. / The purpose of this study was to evaluate in vitro the influence of dimensional changes in denture base acrylic resins submitted to different processing methods on the position of the mandibular condyle. This was done to establish a relation between these dimensional changes and the etiology of temporomandibular disorders in complete denture wearers. This research was divided into two parts. The first part focused on the type of press (conventional water bath or Getom), on the pressing force for flask closure (1000 or 1500 kgf) when processing Lucitone 550 and QC-20 resins, and on the pressing force when processing Acron MC resin. The purpose of the second part was to evaluate the influence of polymerization time on the dimensional stability of five resins, namely Lucitone 550, QC-20, Acron MC, Clássico and Ondacryl. The polymerized upper prostheses were remounted on a fully adjustable articulator, using the maximal intercuspal position (MIP) as reference. Type IV dental stone was poured into the space between the condylar spheres and the condylar walls. After the dental stone dried, the samples were removed from the articulator and their dimensions were measured and submitted to analysis of variance with repeated measures. The following conclusions were drawn: 625 from 630 measurements done showed changes in the position of the “mandibular condyle” and mean values for condylar movement ranged from 0.118 (SD = 0.0968) to 1.956 mm (SD = 0.414) and occurred mainly in the posterior direction on the left side; in most cases where the pressing force influenced the condylar position, the changes were smaller in 1500 kgf group than in the 1000 kgf group; in the cases where the type of press influenced the changes in condylar position, the smallest values were found in both groups, sometimes with Getom and other times with conventional water bath press; polymerization time did not significantly affect the dimensional stability of the dentures and the greatest changes occurred in the posterior direction on the left side with Clássico resin.

Foram desenvolvidos e manufaturados compósitos porosos com estrutura de gradiente funcional em Poli (metacrilato de metila) (PMMA) e Hidroxiapatita (HAp) aplicáveis como implantes ósseos. O PMMA é largamente utilizável e aceito como material de implante tem boas propriedades mecânicas, baixo custo, fácil manufatura, porém é considerado bioinerte. A HAp é uma cerâmica comprovadamente bioativa, porém de baixas propriedades mecânicas, alto custo e de difícil manufatura. O PMMA com estrutura funcional e HAp apresentou valores próximos a 50 MPa, mas com potencial de melhoria. O objetivo deste desenvolvimento é produzir um implante com a sua superfície porosa e bioativa, para que este possa ser osteointegrado em um tempo menor ao tecido hospedeiro, melhorando a relação: material implantado/leito receptor. O conceito é baseado em uma estrutura de núcleo denso em PMMA e camada superficial porosa com superfície bioativa. A camada de PMMA porosa foi desenvolvida utilizando-se o carboximetilcelulose (CMC) como agente porogênico e HAp como agente bioativador da matriz polimérica. Foram elaboradas análises de bicompatibilidade, resistência mecânica, macro e microestrutura. Para testar a biocompatibilidade foram realizados inicialmente testes in vitro com cultura de células VERO, visando investigar a toxicidade dos materiais constituintes, a influência do novo biomaterial em atividades celulares e o comportamento destes em condições próximas daquelas a serem encontradas no ambiente de implantação. Em seguida, os testes in vivo realizados em coelhos averiguaram a interação tecido-material (bioatividade), a biocompatibilidade do material, e a potencialidade do uso do material em aplicação à superfícies (osteointegração). Foi realizada análise histológica dos tecidos explantados, onde os resultados basearam-se na análise da morfologia geral dos componentes teciduais encontrados junto ao implante. A caracterização da superfície foi realizada por testes de rugosidade, por microscopia ótica e eletrônica de varredura. Foram realizados ensaios mecânicos de compressão para analisar a resistência mecânica do biomaterial. Os resultados in vitro mostraram que os materiais utilizados não apresentaram qualquer indício de toxicidade. Através das imagens realizadas em MEV (Microscopia Eletrônica de Varredura) pode se observar o crescimento de células VERO na superfície do material e em direção aos poros da matriz. A análise macroestrutural dos poros também obtida por MEV demonstrou em uma caracterização inicial do material que este apresentou características biomiméticas como poros em formato oblongo e interconectados. A média obtida do tamanho dos poros foi de aproximadamente 250 \'mü\'m. Os resultados dos ensaios mecânicos de compressão mostraram que o PMMA denso é o que mais se aproximou do tecido ósseo cortical com 101 MPa. Por fim, os resultados histológicos apontam para a biocompatibilidade do compósito, tornando-o assim aplicável como camada superficial de implantes. / Were developed and manufactured porous composite with functional gradient structure in Polymethylmethacrylate (PMMA) and hydroxyapatite (HAp) applicable as bone implants. PMMA is widely used and accepted as implant material, has good mechanical properties, low cost, easy manufacturing and considered a bioinert biomaterial, the Hap is a demonstrably bioactive ceramic with poor mechanical properties, high cost and difficult to manufacture. The PMMA functional structure and HAp had values close to 50 MPa, but with potential for improvement. The objective of this development was produced an implant with a porous surface and bioactive to be osteointegrated in a less time, improving the relationship: implanted material/receiver bed. The concept is based on a dense structure core of PMMA and a porous bioactive surface layer. The porous PMMA was developed using the carboxymethylcellulose (CMC) as a porogenic agent and hap to bioactive the PMMA matrix. Biocompatibility tests, mechanical strength tests and macro and microstructure analisys were carried out. To evaluated the biocompatibility of this material were made primarily in vitro tests, the VERO cells were used in vitro analysis aimed investigate the toxicity of the constituent materials, the influence of the new biomaterial in cellular activities and behavior in these conditions close to those to be found in the environment of deployment. Then, in vivo tests conducted in rabbits evaluated the interaction with tissue-material (bioactivity), the biocompatibility of the material, and the potential use of the material in the application areas (osseointegration). Were performed histological analysis of tissues, where the results were based on the analysis of the general morphology of the tissue components found near the implant. The surface characterization was performed by roughness tests, optical microscopy and SEM. Mechanical tests were conducted to examine the compressive strength of biomaterial. Results in vitro showed that the materials did not present any evidence of toxicity. The samples were analyzed by SEM where the growth of cells can be observed in the surface of the material and towards to the pores. The macrostructural analysis also obtained by SEM showed in an initial characterization of the material that presented bone biomimetics characteristics with oblong pores with interconnected. The average pore size obtained was approximately 250 \'mü\'m. The results of mechanical tests showed that the compression of PMMA is the densest approached the cortical bone tissue near 101 MPa. Finally, the histological results point to the biocompatibility of the composite, thus making it applicable to the surface layers of implants.

Indentation hardness, H, has been widely used to characterize the mechanical properties of materials for more than a century because of the following advantages of this technique; (1) it requires small sample and (2) the test is non destructive in nature. Recent technological advances helped in the development of instrumented indentation machines which can record the load, P, vs. displacement, h, data continuously during indentation with excellent load and displacement resolutions. From these, H and the elastic modulus, E, of the indented material can be obtained on the basis of the ‘contact area’ of the indentation at the maximum load. The estimation of true contact area becomes difficult during ‘pile-up’ and ‘sink-in’, commonly observed phenomena while indentation of a low and high strain hardened materials. In order for the better understanding of these phenomena it is important to understand the plastic flow distribution under indenters. It is also important for the prediction of elastic-plastic properties from the P-h data. Recently, there have been considerable theoretical and simulation efforts on this front with a combination of dimensional analysis and finite element simulations. One of the important input parameter for the dimensional analysis is the ‘representative strain’ under the indenter, which is a strong function of the indenter geometry. However there is no comprehensive understanding of the representative strain under the indenter despite several studies till date. One objective of the present thesis is to conduct an experimental analysis of the plastic flow during the sharp indentation. The plastic zone size and shape under conical indenters of different apex angles in a pure and annealed copper were examined by employing the subsurface indentation technique to generate the hardness map. From these isostrain contours are constructed joining the data having similar strain values. The following are the key observations. (1) The plastic strain contours are elliptical in nature, spreading more along the direction of the indenter axis than the lateral direction. (2) The magnitude of the plastic strain in the contact region decreases with increasing the indenter angle. (3) The strain decay in the indentation direction follow a power-law relation with the distance. The estimated representative strains under the indenters, computed as the volume average strain within the elastic-plastic boundary, decreases with increasing indenter angle. We also performed finite element simulations to generate plastic flow distribution under the indenter geometries and compared with the experimental results. The results suggest that the experimental and computed average strains match well. However, the plastic strain contours do not, suggesting that further detailed understanding of the elasto-plastic deformation underneath the sharp indenter is essential before reliable estimates of plastic properties from the P-h curves can be made routinely. The second objective of this thesis is to understand plastic flow in amorphous alloys. It is now well established that plastic deformation in metallic glasses is pressure sensitive, owing to the fundamentally different mechanisms vis-à-vis the dislocation mediated plastic flow in crystalline metals alloys. Early work has shown that the pressure sensitivity of amorphous alloys gets reflected as high constraint factor, C (hardness to yield stress ratio), which sometimes exceed 3.0. In this thesis, we study the temperature dependence of pressure sensitive plastic flow in bulk metallic glasses (BMGs) using C as the proxy for the pressure sensitivity. Experiments on three different BMGs show that C increases with temperature hence the pressure sensitivity. In addition we have carried out finite element simulations to generate P-h curves for different levels of pressure sensitivities and match them with the experimental curves that are obtained at different temperatures. Simulations predict that higher pressure sensitivity index values are required to match the experimental curves at high temperatures confirming that the pressure sensitivity increases with increasing temperature. The fundamental mechanisms responsible for the increase in pressure sensitivity are discussed in detail. Finally we pose a question, is the increase in pressure sensitivity with temperature is common to other amorphous materials such as strong amorphous polymers? In order to answer this question we have chosen PMMA, a strong amorphous polymer. In this study also we have taken C as a proxy to index the pressure sensitivity. Indentation stress-strain curves are constructed at different temperature using spherical indentation experiments. The C values corresponding to different temperatures are determined and plotted as a function of temperature. It is found that C increases with temperature implying that the pressure sensitivity of amorphous polymers also increases with temperature. The micro-mechanisms responsible for the increase in pressure sensitivity are sought.

Orientadores: Júlio Roberto Bartoli, Elizabeth Grillo Fernandes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-22T08:51:19Z (GMT). No. of bitstreams: 1 Cecci_RicardoRodrigoRamos_M.pdf: 4182332 bytes, checksum: 4424cc557c439a1602d15a95921a2b25 (MD5) Previous issue date: 2013 / Resumo: Nanotubos de carbono (NTCs) apresentam características interessantes para aplicações em eletrodos transparentes. Quando dispersos em escala nanométrica são transparentes ao espectro da luz visível e são capazes de conduzir eletricidade após atingirem percolação em matrizes poliméricas isolantes. Neste trabalho, é descrito o uso de nanotubos de carbono de camadas múltiplas (NTCMs) na produção de filmes poliméricos flexíveis transparentes e condutores como alternativa ao uso do óxido de índio dopado com estanho (ITO) em células solares orgânicas. Os nanotubos foram dispersos e purificados em solução aquosa de dodecil sulfato de sódio (SDS) pelos processos de sonicação e centrifugação, e a dispersão monitorada por espectroscopia UV-Vis e potencial ?. Os nanocompósitos foram produzidos via polimerização in situ do monômero metacrilato de metila (MMA) na presença de 0 a 1% p/p NTCs e os filmes depositados através da técnica de revestimento por rotação a alta velocidade (spin coating). A reação de polimerização foi acompanhada pela calorimetria exploratória diferencial (DSC). Verificou-se que na presença de NTCs, a taxa de conversão do monômero é acelerada. A cinética de degradação térmica foi avaliada pelo método de Broido utilizando a análise termogravimétrica (TGA). Foi observado que os NTCs aumentam a estabilidade térmica do PMMA, retardando a degradação por despolimerização. Estudos por espectroscopia FT-IR mostraram uma banda de absorção em 1601 cm-1, (C=C), a qual não é característica do PMMA, indicando que os NTCs participam da polimerização do PMMA. Para concentrações de até 1% p/p de NTCs, os filmes PMMA/NTC apresentaram excelentes propriedades ópticas. Ou seja, baixo coeficiente de absorção, na ordem de 103 cm-1, altos valores de gap óptico (Eopt), entre 3,2 e 4,14 eV, e alta transparência por todo espectro visível, entre 88 e 93%. Nas mesmas concentrações, foi observada uma diminuição substancial na resistividade elétrica dos filmes em 8 ordens de grandeza (de 1016 para 108 ?/quadrado), comparados ao filme de PMMA puro. Entretanto, a faixa de resistividade alcançada ainda é típica de materiais isolantes. Estudos de otimização poderiam originar filmes PMMA/NTC como uma alternativa promissora para ITO em OPVs / Abstract: Carbon nanotubes (CNTs) have interesting features for applications in transparent electrodes. When dispersed at the nanoscale, they become transparent within the visible range and are able to conduct electricity after reaching the percolation threshold in an insulating polymer matrix. In this work, the use of multi-walled carbon nanotubes (MWCNTs) is described for the production of flexible transparent conducting polymer films as an alternative to the use of indium-tin oxide (ITO) in organic solar cells. The nanotubes were dispersed and purified in an aqueous solution of sodium dodecyl sulfate (SDS) by the process of sonication and centrifugation, and the dispersion monitored by UV-Vis spectroscopy and ? potential. The nanocomposites were produced via in situ polymerization of the monomer methyl methacrylate (MMA) in the presence of 0 to 1 %wt. of CNTs. The films were deposited by the spin-coating technique. The polymerization reaction was monitored by differential scanning calorimetry (DSC). It was found that in the presence of CNTs, the conversion rate of the monomer is accelerated. The kinetics of thermal degradation was measured according to the Broido's method by using thermogravimetric analysis (TGA). It was observed that CNTs increase the thermal stability of PMMA, slowing degradation by depolymerization. FT-IR data showed an absorption band at 1601 cm-1 (C = C), which is not characteristic of PMMA, indicating that the CNTs takes place in the polymerization of PMMA. For concentrations up to 1wt% of CNTs, the PMMA/CNT films had excellent optical properties, i.e., a low absorption coefficient in the order of 103 cm-1, wide optical gap (Eopt) between 3.2 and 4.14 eV, and high transparency within the whole visible range, between 88 and 93%. In the same concentrations, the electrical resistivity of the films dropped by 8 orders of magnitude (from 1016 to 108 ?/sqr), compared to the pure PMMA film. Even though this electrical resistivity value is typical of insulating materials, further optimization studies could provide PMMA/CNT films as a promising alternative to ITO in OPV / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Orientador: Ana Lucia Machado / Resumo: Devido ao aumento da tolerância dos microrganismos aos antimicrobianos atualmente disponíveis, existe a necessidade de desenvolvimento de métodos alternativos para o controle das infecções. Na primeira etapa dessa pesquisa, óxidos bimetálicos foram sintetizados por meio dos métodos hidrotermal assistido por micro-ondas e co-precipitação, variando-se as condições de síntese, como temperatura, pH, utilização ou não de surfactantes e tipos de solventes. Os diferentes microcristais de tungstato de prata (α-Ag2WO4) e molibdato de prata (β-Ag2MoO4) obtidos foram caracterizados por difração de Raios X (DRX), microscopia eletrônica de varredura por emissão de efeito de campo (MEV-EC), microscopia eletrônica de transmissão (MET), espectroscopia de energia dispersiva de raios-X (EDX), espectroscopia Raman e mensurações de fotoluminescência (PL) e UV-Vis. A atividade antimicrobiana desses compostos contra células planctônicas de Staphylococcus aureus resistente à meticilina - SARM, Escherichia coli (E. coli) e Candida albicans (C. albicans) foi avaliada por meio da determinação das concentrações inibitórias (CIM) e bactericida/fungicida mínimas (CBM/CFM). Além disso, com base nos testes de CIM, CBM e CFM, os compostos que proporcionaram os melhores resultados (α-Ag2WO4 irradiado e α-Ag2WO4 e β-Ag2MoO4, ambos sintetizados em álcool) foram também avaliados quanto à inibição da formação de biofilmes de SARM, E. coli e C. albicans, através de contagem de unidades formadoras de colônias por ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Due to the increased tolerance of the microrganisms to the available antimicrobial drugs, there is a need of development of alternative methods for infection control. In the first part of this study, bimetallic oxides were synthesized by hydrothermal microwave-assisted and coprecipitation methods, varying synthesis conditions, as presence or absence of surfactants and types of solvents used. The different microcrystals of α-Ag2WO4 and β-Ag2MoO4 obtained were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy diffraction spectroscopy (EDS), Raman spectroscopy and photoluminescence measurements (PL) and UV-Vis. Their antimicrobial activity was evaluated against planktonic cells of methicillin - resistant Staphylococcus aureus - MRSA, Escherichia coli (E. coli) and Candida albicans (C. albicans) by the determination of inhibitory concentrations (MIC) and bactericidal/fungicidal concentrations (MBC/MFC). Based on the MIC, MBC and MFC values, the microcrystals that provided the best results (α-Ag2WO4 irradiated and α-Ag2WO4 and β-Ag2MoO4, both synthesized in alcohol) were also evaluated for their ability to inhibit biofilm of MRSA, E. coli and C. albicans, by counting the CFU/mL, dry weight determination, and analysis using confocal laser scanning microscopy (CLSM) and FE-SEM. Other method for infection control evaluated in the second part of this research, was the deposition of SiO2/Ag thi... (Complete abstract click electronic access below) / Doutor