Background Surface treatments and irregularities in the surfaces may affect the fracture of ceramics. The effects of various treatments on the surface texture of different types of ceramic cores/substructures was therefore qualitatively, quantitatively and numerically evaluated. Since fractures in ceramics are not fully understood, the fracture behavior in dental ceramic core/substructures was also studied using both established laboratory methods and newly developed numerical methods. Methods The surfaces of dental ceramic cores/substructures were studied qualitatively by means of a fluorescence penetrant method and scanning electron microscopy, quantitatively evaluated using a profilometer and also numerical simulation. In order to study fracture in zirconia-based fixed partial denture (FPD) frameworks, fractographic analysis in combination with fracture tests and newly developed two-dimensional (2D) and three-dimensional (3D) numerical modeling methods were used. In the numerical modeling methods, the heterogeneity within the materials was described by means of the Weibull distribution law. The Mohr–Coulomb failure criterion with tensile strength cut-off was used to judge whether the material was in an elastic or failed state. Results Manual grinding/polishing could smooth the surfaces on some of the types of dental ceramic cores/substructures studied. Using the fluorescence penetrant method, no cracks/flaws apart from milling grooves could be seen on the surfaces of machined zirconia-based frameworks. Numerical simulations demonstrated that surface grooves affect the fracture of the ceramic bars and the deeper the groove, the sooner the bar fractured. In the laboratory tests the fracture mechanism in the FPD frameworks was identified as tensile failure and irregularities on the ceramic surfaces could act as fracture initiation sites. The numerical modeling codes allowed a better understanding of the fracture mechanism than the laboratory tests; the stress distribution and the fracture process could be reproduced using the mathematical methods of mechanics. Furthermore, a strong correlation was found between the numerical and the laboratory results. Conclusion Based on the findings in the current thesis, smooth surfaces in areas of concentrated tensile stress would be preferable regarding the survival of ceramic restorations, however, the surfaces of only some of the ceramic cores/substructures could be significantly affected by manual polishing. The newly developed 3D method clearly showed the stress distribution and the fracture process in ceramic FPD frameworks, step by step, and seems to be an appropriate tool for use in the prediction of the fracture process in ceramic FPD frameworks.

Chronic ulcers are an important and costly medical issue, causing their sufferers a large amount of pain, immobility and decreased quality of life. The common pathology in these chronic wounds is often characterised by excessive proteolytic activity, leading to the degradation of both the extracellular matrix, as well as key factors critical to the ulcer's ability to heal. As matrix metalloproteinases (MMPs), a large family of zinc-dependent endopeptidases, have been shown to have increased activity in chronic wound fluid (CWF), it was hypothesised that this specific proteolytic activity was directly related to an ulcer's chronic nature. Although previous studies have identified elevated proteases in CWF, many have reported contradictory results and therefore the precise levels and species of MMPs in CWF are poorly understood. The studies reported herein demonstrate that MMP activity is significantly elevated in CWF compared with acute wound fluid (AWF). In particular, these studies demonstrate that this proteolytic activity can be specifically attributed to MMPs and not another class of proteases present in wound healing. Furthermore, it is shown that MMP-9 is the predominant protease responsible for matrix degradation by CWF and is an indicator of the clinical status of the wound itself. Moreover, MMP-9 can be inhibited with the bisphosphonate alendronate, in the form of a sodium salt, a functionalised analogue, and also tethered to a synthetic biocompatible hydrogel compromised of aqueous poly (2-hydroxy methacrylate) PHEMA synthesised in the presence of poly(ethylene glycol) (PEG). Together, these results highlight the potential use of a tethered MMP inhibitor as an improved ulcer treatment to inhibit protease activity in the wound fluid, while still allowing MMPs to remain active in the wound bed where they perform vital roles in the activation of growth-promoting agents and immune system regulation.

Conventional glass ionomer cements (GICs), which continue to gain acceptance as superbly biocompatible dental materials, were first released in the early 1970s as a result of research into combining the advantages of silicate cements and polyalkenate cements. The chemistry of GICs is based upon the aqueous reaction between an ion-leachable fluoride glass and polyacid which yields the final cross-linked insoluble ionomer (ionic polymer). The significant advantages of GICs include direct adhesion to tooth structures, fluoride release, minimal dimensional change on curing, significant ease of use and superb biocompatibility, to the extent that affected proximal tooth structures may be retained, remineralised , and strengthened against further caries. GICs have, however, been unfavourably compared with other restorative materials in their mechanical properties and setting characteristics, in particular their relative weakness, the time limitations for the acid-base reaction to proceed to acceptable maturity, and the susceptibility of the immature cement to water sorption or desiccation.

An enzyme treatment process for the pre-tanning of sheepskins has been previously reported by the Leather and Shoe Research Association of New Zealand (LASRA) as an alternative to current industry operations. The newly developed process had marked benefits over conventional processing in terms of a lowered energy usage (73%), processing time (47%) as well as water use (49%), but had been developed as a “proof of principle’’. The objective of this work was to develop the process further to a stage ready for adoption by industry. A process ready for adoption by industry is one that is able to generate good quality products (good quality products are those that has solids removed to industry standards, without visible damages to grain surface, evenly dyed etc.), require minimal changes to plant or operation layout and reduce usage of resources (e.g. water and chemicals). Mass balancing was used to investigate potential modifications for the process based on the understanding developed from a detailed analysis of preliminary design trials. Results showed that a configuration utilising a 2 stage counter-current system for the washing stages and segregation and recycling of enzyme float prior to dilution in the neutralization stage was a significant improvement. Benefits over conventional processing include a reduction of residual TDS by 50% at the washing stages and 70% savings on water use overall. Benefits over the un-optimized LASRA process are reduction of solids in product after enzyme treatment and neutralization stages by 30%, additional water savings of 21%, as well as 10% savings of enzyme usage. The optimized (new) LASRA process uses existing equipment and requires no additional outlay of capital. The process is now developed to a point where it should be trialled at industrial scale.

Current research efforts are directed at developing competitive processes that can utilize lignocellulose as a feedstock for biorefineries. The purpose of this study was to investigate methods of processing lignocellulosic material so that its monosacharides can be more easily accessed for fermentation, the lack of which is hindering the economics and widescale adoption of lignocellulosic biorefining. The monosaccharides are of interest because they can be used by Clostridium beijerinckii downstream of P. chrysosporium and C. thermocellum in a sequential bioprocess to produce butanol. Butanol is an attractive biofuel because it can be utilized without modifying current transportation infrastructure. Butanol is also used as a starting material in organic synthesis. In the first study, the potential for C. thermocellum' s (ATCC 27405) cellulase system to operate outside its optimal temperature range in a high-solids environments was assessed by quantification of the fermentation products lactate, acetate, and ethanol and by quantification of xylose, glucose, and cellobiose remaining. Additionally, the lignin degrading white-rot fungus Phanerochaete chrysosporium RP 78 was investigated as a potential pretreatment for lignocellulose. Elevated temperatures required for Clostridium thermocellum fermentation were examined as a means to improve poor competiveness that is characteristic of P. chrysosporium on unsterile corn stover substrate.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-01-25Bitstream added on 2014-06-13T18:50:40Z : No. of bitstreams: 1 nogueira_ra_me_bauru_prot.pdf: 2628699 bytes, checksum: 548bffb406de71f06f0ab9ae6a52d7c8 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A utilização de biomateriais do reparo do tecido ósseo tem revolucionado a Ortopedia e a Odontologia atuais. Um metal estudado para estas aplicações é o titânio e suas ligas, pois possuem um excelente grau de biocompatibilidade com o organismo humano, uma excelente resistência à corrosão em meio biológico e uma ótima relação resistência mecânica/densidade. Estas propriedades são fortemente influenciadas pela presença de lementos intersticiais e as medidas de atrito interno têm sido muito utilizadas para verificar o comportamento destes elementos em materiais. O objetivo neste trabalho foi estudar o efeito de elementos intersticiais nas propriedades da liga Ti-10Mo (% em peso), por meio de medidas de difração de raios X, microscopia eletrônica e varredura, testes de citotoxidade, corrosão e espectroscopia mecânica. As amostras foram submetidas a tratamentos térmicos de recozimento e dopagem com oxigênio. Os testes de biocompatibilidade mostraram que não houve nenhuma resposta indireta. Os extratos dos materiais não interferiram no desenvolvimento, crescimento e proliferação das células. Foi detectada uma melhora na taxa de corrosão, juntamente com um aumento do potencial de corrosão, com a dopagem do material, características estas interessantes para um biomaterial. Os resultados de espectroscopia mecânica mostraram a presença de uma estrutura de relaxação após a dopagem com oxigênio em torno de átomos dos elementos que compõem a liga. Observou-se que a adição de oxigênio intersticial causou um aumento no módulo de elasticidade, o que é ruim quando se trata de um biomaterial para implantes ortopédicos. / The use of the biomaterials in the repair of the bone tissue has been revolutionizing the Orthopedics and the Odontology. A metal very studied for these applications is the titanium and its alloys, because they possess an excellent corrosion resistance in a biological media and a good relationship mechanical strength/density. These properties are strongly influenced by the presence of interstitial elements and the internal friction measurements have been a lot used to verify the behavior of these interstitial elements in materials. The objective of this work was to study the effect of interstitial elements in the properties of the Ti-10Mo (%in weight) alloy, through X-ray diffraction, scanning electron microscopy, cytotoxicity tests, corrosion and mechanical spectroscopy. The samples were submitted to heat treatments of annealing and oxygen doping. The biocompatibility tests showed that there was not any indirect cytotoxic answer. The extracts of the materials didn't interfere in the development, growth and proliferation of the cells. An increase in the corrosion rate was detected, with an increase of the corrosion potential, with the oxygen doping, interesting for applications as biomaterial. The mechanical spectroscopy results showed the presence of a relaxation structure after the oxygen doping that was attributed mainly to the stress-induced ordering of the oxygen atoms around the atoms that compose the alloy. It was observed an increase in the elasticity with the oxygen doping, what is bad when it is a biomaterial.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-26Bitstream added on 2014-06-13T18:50:41Z : No. of bitstreams: 1 silva_lm_me_bauru_prot.pdf: 4671896 bytes, checksum: eb79f47df3c9400614b7c74b221948a0 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os recentes avanços científicos permitiram um aumento significativo na qualidade de vida e por consequência, na longevidade. Como consequência disso, a população de idosos aumentou consideravelmente e com isso, doenças relacionadas à idade como osteoporose levam o governo a ter que gastar consideráveis quantias em próteses ortopédicas. Há também uma grande demanda devido aos acidentes de trânsito. Os materiais metálicos mais usados na manufatura de próteses são divididos em três grupos: aços inoxidáveis, ligas a base de Co e ligas a base de Ti. Dentre estes três grupos, os biomateriais mais utilizados são aqueles a base de Ti, pois apresentam excelente biocompatibilidade e elevada resistência à corrosão. A liga de Ti mais utilizada para aplicações biológicas é a liga Ti-6Al-4V, porém alguns estudos associam o V a efeitos citotóxicos e reações adversas em tecidos, enquanto o Al tem sido associado com desordens neurológicas. Para sanar este problema, novas ligas de Ti que apresentam em sua composição elementos como Nb, Ta, Zr, Fe e Mo estão sendo pesquisadas e o desenvolvimento de novas ligas de Ti contendo Nb para aplicação ortopédica é um tema de grande importância social e tecnológica, pois o Nb é um elemento não tóxico e não alergênico, possui elevada biocompatibilidade e tem o Brasil como seu maior produtor, daí a importância de desenvolvimento de ciência e tecnologia utilizando tal material. A presença de elementos intersticiais (O, C, N e H) altera de significativamente as propriedades mecânicas da liga, principalmente suas propriedades elásticas, causando endurecimento ou enfraquecimento da liga. As medidas de espectroscopia mecânica são uma ferramenta poderosa para o estudo da interação destes elementos substitucionais e intersticiais com os elementos que compõem a liga. Este trabalho apresenta o efeito... / Recent scientific advances have led to a significant increase in life's quality and consequently, longevity. As a result, the elderly population has increased considerably and thus age-related disease such as osteoporosis lead the government to spend considerable sums of money with orthopedic prostheses. There is also a great demand for orthopedic prostheses due to accidents. The metallic materials commonly used in the manufacture of prostheses are divided into three groups: stainless steel, Co-based alloys and Ti-based alloys. Among these three groups, the most widely used as a biomaterial are the Ti-based alloys, since they have excellent biocompatibility and high corrosion resistance. The most used Ti-based alloy for biological applications is the Ti-6Al-4V alloy, but some studies associate the V to the cytotoxic effects and adverse reactions in tissues, while Al has been associated with neurological disorders. To solve this problem, new Ti-based alloys that have in their composition elements such as Nb, Ta, Zr, Fe and Mo are being researched. The development of new Ti-based alloys containing Nb for orthopedic application is a topic of great social and technological relevance, as this element is a non-toxic, non allergenic, has high biocompatibility and has Brazil as its biggest producer, hence the importance of development of science and technology using this material. The presence of interstitial elements (O, C, N and H) changes significantly the mechanical properties of the alloy, particularly its elastic properties, causing hardening or softening of the alloy. Mechanical spectroscopy measurements represent a powerful tool for studying the interaction of substitutional and interstitial elements with the metal matrix. This work presents the effect of interstitial oxygen in solid solution in some mechanical properties and biocompatibility of two alloys of the Ti-Nb system... (Complete abstract click electronic access below)

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-10T19:06:53Z No. of bitstreams: 1 LEANDRO RODRIGUES PEREIRA - DISSERTAÇÃO PPG-CEMat 2014..pdf: 3148791 bytes, checksum: 14fe302e950234a170c84cd8636b58ad (MD5) / Made available in DSpace on 2018-04-10T19:06:53Z (GMT). No. of bitstreams: 1 LEANDRO RODRIGUES PEREIRA - DISSERTAÇÃO PPG-CEMat 2014..pdf: 3148791 bytes, checksum: 14fe302e950234a170c84cd8636b58ad (MD5) Previous issue date: 2014-07-17 / Desde o final do século XIX, foram utilizados vários materiais para o aumento da mama. Como exemplos, citam-se espumas de poliuretano e polietileno, bolas de vidro, gutta percha, entre outros. O uso de silicone para fins de aumento de mama se iniciou em 1961 e, partir de então, as empresas desenvolveram inovações ao processo de fabricação de implantes mamários incluindo a inserção de camadas de barreiras para evitar a migração de gel. Em 2012, foi publicada a Resolução ANVISA RDC nº 16 que estabeleceu os requisitos mínimos de identidade e qualidade para os implantes mamários de silicone. Desta forma, este trabalho propõe a avaliar os implantes mamários regularizados no Brasil e realizar a caracterização morfológica, estrutural e mecânica de implantes mamários de silicone comercializados no Brasil em conformidade com as Normas Vigentes, por meio de caracterizações: Microscopia Ótica – MO, Microscopia Eletrônica de Varredura – MEV com espectroscopia de Energia Dispersiva- EDS e avaliação do comportamento mecânico quando submetidos ao Ensaio de Tração, sendo avaliados os quesitos estabelecidos na norma ISO 14607:2007. Com base nos resultados obtidos neste trabalho pode-se concluir que todas as membranas de implantes mamários avaliadas apresentaram-se adequadas para uso como biomaterial. Verificou-se também a oportunidade de melhoria normativa, com estabelecimento de parâmetro mínimo de desempenho para o ensaio de resistência ao rasgo, estabelecido na norma ISO 14607:2007. / Since the late nineteenth century, various materials were used for breast augmentation. Polyurethane, polyethylene, glass balls, gutta percha, among others materials were used. The use of silicone for breast augmentation purposes began in 1961 and, since then, companies have developed innovations to the manufacturing process of breast implants including the insertion of barrier layers to prevent migration of silicone gel. In 2012 was published the ANVISA Resolution RDC No. 16 which established minimum requirements for identity and quality for silicone breast implants. Thus, this study aims to evaluate six brands of regularized breast implants in Brazil and perform morphological, structural and mechanical caracterization in accordance with current standards. Optical Microscopy - MO, Electron Microscopy Scanning - SEM with Energy Dispersive Spectroscopy- EDS and evaluation of the mechanical behavior when subjected to tensile test according to ISO 14607:2007 standard. Based on the results obtained in this study, it can be concluded that all the membranes of breast implants had to be suitable for use as a biomaterial, complying with regulatory requirements. There is also an opportunity to improve the ISO 14607:2007 standard, establishing a minimum performance requirement for testing elastomer shell tear resistance.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-18T17:04:56Z No. of bitstreams: 1 LEONARDO SARMENTO MEIRA GADELHA - DISSERTAÇÃO PPG-CEMat 2014..pdf: 1520712 bytes, checksum: 8f477b0a9d2403096c41524ecdb9cda1 (MD5) / Made available in DSpace on 2018-04-18T17:04:56Z (GMT). No. of bitstreams: 1 LEONARDO SARMENTO MEIRA GADELHA - DISSERTAÇÃO PPG-CEMat 2014..pdf: 1520712 bytes, checksum: 8f477b0a9d2403096c41524ecdb9cda1 (MD5) Previous issue date: 2014-08-07 / As cerâmicas são materiais sólidos não metálicos inorgânicos. Por apresentar natureza refratária, dureza e inércia química frente às condições adversas encontradas na cavidade bucal, as cerâmicas foram introduzidas como material odontológico devido a sua biocompatibilidade, estabilidade de cor em longo prazo, resistência ao desgaste e a sua capacidade de serem conformadas em formas precisas. Destacam-se entre as cerâmicas utilizadas nos implantes ortodônticos a zircônia e a hidroxiapatita por possuirem propriedades mecânicas muito semelhantes à de metais e cor semelhante à cor do dente. Baseado nestas informações este trabalho tem como objetivo estudar as propriedades de blocos sinterizados de Zircônia/Hidroxiapatita como perspectiva de aplicação como biomaterial. Verificou-se a possibilidade de obter blocos Zircônia/Hidroxiapatita, controlando suas características morfológicas e cristalinas pela adição de hidroxiapatita, com potencial para ser aplicado como biomaterial. / Ceramics are inorganic non-metallic solids. By presenting refractory nature, hardness and chemical inertness face of the adverse conditions found in the oral cavity, ceramics were introduced as dental material due to its biocompatibility, color stability for long-term wear resistance and its ability to be formed into precise shapes. Prominent among the ceramics used in orthodontic zirconia implants and hydroxyapatite to possess mechanical properties very similar to the metal and color similar to the color of the tooth. Based on this information this work was to study the properties of sintered blocks of zirconia / hydroxyapatite as application perspective as a biomaterial. It has been found the possibility to obtain zirconia / hydroxyapatite blocks, controlling their morphological and crystalline characteristics by adding hydroxyapatite, with a potential to be applied as a biomaterial.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-18T17:17:40Z No. of bitstreams: 1 WALFREDO DA SILVA CALMON - DISSERTAÇÃO PPG-CEMat 2014..pdf: 2111423 bytes, checksum: e64a02519d1c3b8005ac197552feadca (MD5) / Made available in DSpace on 2018-04-18T17:17:40Z (GMT). No. of bitstreams: 1 WALFREDO DA SILVA CALMON - DISSERTAÇÃO PPG-CEMat 2014..pdf: 2111423 bytes, checksum: e64a02519d1c3b8005ac197552feadca (MD5) Previous issue date: 2014-08-14 / Este trabalho tem por objetivo avaliar membranas de silicone que envolve o implante mamário preenchido com gel de silicone, no intuito de verificar a conformidade das suas propriedades. Como estratégia utilizou-se das técnicas de caracterização para analisar os parâmetros físico-químicos em três lotes diferentes de implante mamário. Os resultados experimentais encontrados foram comparados com valores referenciados em padrões estabelecidos em norma ou na literatura. Com isso, foi possível analisar alguns atributos que influenciam na qualidade desses implantes. Os resultados de microscopia por MO e MEV não detectaram anomalias nas superfícies das amostras. Foram detectados pelo ensaio de espectroscopia por EDS os elementos carbono, silício e oxigênio, como também identificados os metais ferro, cálcio, níquel e cromo nas amostras ensaiadas. O teste de alongamento de duas amostras não atendeu o requisito normativo. Conclui-se, portanto, que a integridade das membranas de silicone foi comprometida, por conta do seu comportamento mecânico, em duas das três amostras ensaiadas. / This work aims to evaluate silicon membranes surrounding the breast implant filled with silicone gel, in order to verify the conformity of its properties. As a strategy, we used the characterization techniques to analyze the physicochemical parameters in three different batches of breast implant. The experimental results were compared with values referenced in standard or standards established in the literature. Thus, it was possible to analyze some attributes that influence the quality of these implants. The results of OM and SEM microscopy did not detect anomalies in the surfaces of the samples. Were detected by testing the EDS spectra of carbon, silicon and oxygen elements, also identified as metals iron, calcium, nickel and chromium in the test samples. The stretching test two samples did not meet the regulatory requirement. Therefore, it is concluded that the integrity of the silicone membranes was compromised, because its mechanical behavior, in two of the three samples tested.