<p> <p>&nbsp / </p> <p align="left">&nbsp / </p> <p>&nbsp / </p> </p> <p align="left">The aim of this study was to produce useful composite materials from fly ash, a major waste product of coal combustion from power plants. Polyaniline-fly ash (PANI-FA) composites were prepared by in situ polymerisation of aniline in the presence of Fly Ash (FA) by two slightly different methods. In one case polystyrene sulphonic acid (PSSA) was used as a stabilizer and in another case the starting materials (aniline and FA) were aged before oxidation. The aging procedure formed nanotubes that have cross-sectional diameters of 50-110 nm. The other procedure produced nanotubes with a diameter of 100-500 nm and the length of up to 10&mu / m. The presence of metal oxides and silica in FA were responsible for the formation of nanorods in PANI-PSSA-FA.. The formation of the composites was confirmed by UV-Vis and FTIR. The UV-Vis showed maximum absorbance at 330-360 nm ( due to &pi / -&pi / * transition of benzoid rings) and 600-650 nm(due to charge transfer excitons of quinoid rings), which are characteristics of emaraldine base. The electrochemical analysis of the composites showed that the composites were conductive and electroactive. The Cyclic Voltammetry of PANI-PSSA-FA showed three redox couples which are characteristics of sulphonated PANI. The morphology of the composites was studied by Scanning Electron Microscopy (SEM) and showed that our methods gave composites with improved homogeneity as compared to other reported methods. Thermo Gravimetric analysis (TGA) showed that the presence of FA in the composites improves the thermal stability of the composites by up to 100 0C.<br /> &nbsp / </p>

Owing to the importance of gold nanoparticles in catalysis, designing of them has become a major focus of the researchers. Most of the current methods available for the synthesis of gold nanoaprticles (GNPs) suffer from the challenges of polydispersity, stability and use of toxic and harmful chemicals. To overcome these limitations of conventional methods, in our present study, we made an attempt to design a method for the green synthesis of monodispersed and stable gold nanoparticles by sugars which act as reducing and stabilizing agent. Characterization of synthesized nanoparticles was done by using various analytical techniques such as transmission electron microscope (TEM), dynamic light scattering spectroscopy (DLS), UV-Vis spectroscopy, scanning electron microscopy and electron dispersion spectroscopy. The synthesized sugar GNPs (S-GNPs) were spherical in shape and in the size range of 10 ± 5 nm. p-Nitrophenol reduction assay was used as a model system to determine the catalytic reduction activity of various sugar capped GNPs, monosaccharides (fructose), disaccharide (sucrose) and trisaccharide (raffinose) GNPs. The effect of temperature and the size of ligand on catalytic activity was also evaluated at different temperature using UV-Vis spectrometer. Using the spectroscopic data, rate constant (k) for three sugar capped GNPs was determined followed by its activation energy (Ea) and exponential (A) factor.

Electron BackScattered Diffraction (EBSD) systems can be considered as a tool providing three kinds of responses: EBSD patterns (EBSPs) themselves, an indexing response (orientation data), and an intensity response (also called Band Contrast "BC", Image Quality "IQ", or Pattern Quality "PQ or P"). This work focused on the characterization and development of the intensity response. For now, the intensity response cannot be used for quantitative microstructural analyses, including strain analyses of materials. Indeed, this response is affected by several material and experimental conditions. Moreover, properties of the intensity response (strain sensitivity, reproducibility, exact relation with EBSP quality or diffraction band intensities) are not well-known and understood. This project constitutes an exploratory study on the development of the intensity response for quantitative strain analyses of materials. A new modelling and statistical approach is presented and assessed for transforming the raw (current) intensity response (values and grey-tones of intensity images) of commercial EBSD systems into an accurate and reproducible parameter allowing objective visualization and measurements of strain. / Les systèmes de diffraction des électrons rétro-diffusés (EBSD) peuvent être considérés comme un outil offrant trois types de réponses: les patrons EBSD (EBSPs), la réponse d'indexation (données d'orientation) et la réponse d'intensité (aussi appelée Contraste de Bande «BC », Qualité d'Image « IQ », ou Qualité de Patron « PQ ou P »). Le présent projet s'est concentré sur la caractérisation et le développement de la réponse d'intensité. En effet, pour l'instant, la réponse d'intensité ne peut être utilisée pour réaliser des analyses microstructurales quantitatives des matériaux. En effet, cette réponse est influencée par de nombreux facteurs relatifs au matériau analysé et aux conditions expérimentales utilisées. De plus, les propriétés de la réponse d'intensité (sensibilité à la déformation, reproductibilité, relation exacte avec la qualité des EBSPs ou les intensités des bandes de diffraction) ne sont pour l'instant pas bien connues ni même compnses. Le présent projet représente donc une étude exploratoire visant le développement de la réponse d'intensité des systèmes EBSD commerciaux pour l'analyse quantitative de la déformation des matériaux. Dans ce projet, une approche de modélisation statistique est présentée et évaluée afin de transformer la réponse d'intensité actuelle (valeurs et tons de gris des images d'intensité) des systèmes EBSD commerciaux en une réponse précise et reproductible permettant de visualiser et de mesurer objectivement la déformation.

Thesis (MSc Food Sc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Hectolitre mass (HLM) measurements allow rapid and accurate determination of grain density. HLM devices from different countries (Australia, Canada, France, Germany, South Africa, the United Kingdom and the United States of America [USA]) have been investigated for their effect on the HLM measurements of oats. In addition, the potential of near infrared (NIR) hyperspectral imaging has been evaluated to distinguish between oat samples with different HLM values. Comparing HLM measurements obtained from the respective devices, the USA and the South African devices resulted in significantly (P<0.05) lower HLM values compared to the other devices where as the German device resulted in higher values (P<0.05) than the other devices. HLM values from all the devices were highly correlated with intra-class correlation (ICC) consistency values of at least 0.90. These high correlations would allow direct replacement of the South African device with any of the other devices. The equipment selected as replacement should ideally be calibrated according to the ISO 7971-3 standard (i.e. the device currently used in Germany). HLM values significantly (P<0.05) increased when oat samples were rubbed before measurements were made, indicating the importance of continuation of this sample preparation step. The investigation on the effect of the operator on HLM determinations showed that the unskilled operator measured HLM values significantly different to those obtained by the skilled operator. This emphasises the importance of training in spite of HLM measurements being a simple procedure. A poor correlation (r = 0.18) was found between protein content and HLM values of oat samples. Moisture content significantly affected the HLM values of oats and results clearly showed a decrease in HLM values with increasing moisture content. Scanning electron microscope (SEM) micrographs revealed that the starch granules became swollen and that they increased in size with an increase in moisture content, resulting in a decrease in HLM. NIR hyperspectral imaging offers the testing of individual grains non-destructively. This is often required by plant breeders because they subsequently need to plant selected grains. NIR offers this option to plant breeders. NIR hyperspectral imaging, which combines NIR spectroscopy with digital imaging, was used to distinguish between six oat samples with varying HLM values. NIR spectroscopic differences were observed between the images of the two samples with the highest and lowest HLM values (60.2 and 49.35 kg.hL-1). Less distinct differences were observed in the NIR hyperspectral images of two samples differing by less than 2.0 kg.hL-1. Although mixed oat samples were used, these preliminary results established the possible use of NIR hyperspectral imaging in evaluating oat samples from breeding trials. The use of this technique could also be extended to evaluation of other quality characteristics of oats. / AFRIKAANSE OPSOMMING: Hektolitermassa- (HLM-)metings maak snelle en akkurate bepaling van korreldigtheid moontlik. HLM-toestelle van verskillende lande (Australië, Kanada, Frankryk, Duitsland, Suid-Afrika, die Verenigde Koninkryk en die Verenigde State van Amerika) is ondersoek vir hulle uitwerking op die HLM-metings van hawer. Daarby is die potensiaal van nabyinfrarooi- (NIR-)hiperspektrale beelding geëvalueer om tussen hawermonsters met verskillende HLM-waardes te onderskei. Tydens vergelyking van HLM-metings verkry van die onderskeie toestelle, het die Amerikaanse en die Suid-Afrikaanse toestelle beduidend (P<0.05) laer HLM-waardes opgelewer in vergelyking met die ander toestelle terwyl die Duitse toestel hoër waardes (P<0.05) as die ander toestelle getoon het. Daar was hoë korrelasies tussen die HLM waardes verkry van die apparate met intraklaskorrelasie (IKK) konsekwentheidwaardes van ten minste 0.90. Hierdie hoë korrelasies sou direkte vervanging van die Suid-Afrikaanse toestel met enige van die ander toestelle moontlik maak. Die toerusting gekies as vervanging sou ideaal gesproke in ooreenstemming met die ISO 7971-3 standaard gekalibreer kon word (bv. die toestel wat tans in Duitsland gebruik word). HLM-waardes het beduidend (P<0.05) verhoog toe hawermonsters gevryf is voor metings gemaak is, wat dui op die belang van verlengde gebruik van hierdie stap tydens die voorbereiding van monsters. Die ondersoek na die uitwerking van die operateur op HLM-bepalings het getoon dat die onervare operateur HLM-waardes beduidend verskillend gemeet het teenoor dié verkry deur die ervare operateur. Dit beklemtoon die belang van opleiding ten spyte daarvan dat HLM-metings ’n eenvoudige prosedure is. ’n Swak korrelasie (r = 0.18) is aangetref tussen proteïeninhoud en HLM-waardes van hawermonsters. Voginhoud het die HLM-waardes van hawer beduidend beïnvloed en resultate het duidelik ’n styging in HLM-waardes met verhoging van die voginhoud getoon. Aftaselektronmikroskoop- (AEM-)mikrobeelde het aangedui dat die styselgranules swel en in grootte toeneem met verhoging van die voginhoud, wat aanleiding gee tot ’n verlaging in HLM. NIR-hiperspektrale beelding maak die toets van individuele korrels op niedestruktiewe wyse moontlik. Dit word dikwels deur plantkwekers vereis aangesien hulle na toetsing uitgesoekte korrels moet plant. Nabyinfrarooi bied hierdie opsie aan plantkwekers. NIR-hiperspektrale beelding, wat NIRspektroskopie met digitale beelding kombineer, is gebruik om te onderskei tussen ses hawermonsters met wisselende HLM-waardes. NIR-spektroskopiese verskille tussen die beelde van die twee monsters met die hoogste en laagste HLM-waardes (60.2 en 49.35 kg.hL-1) is waargeneem. Minder duidelike verskille is in die NIR-hiperspektrale beelde van twee monsters wat met minder as 2.0 kg.hL-1 verskil het, waargeneem. Alhoewel gemengde hawermonsters gebruik is, het hierdie voorlopige resultate die moontlike gebruik van NIR-hiperspektrale beelding by die evaluering van hawermonsters van kweekproewe vasgestel. Die gebruik van hierdie tegniek sou ook uitgebrei kon word tot die evaluering van ander kwaliteitseienskappe van hawer.

Orientador: Sizenando de Toledo Porto Neto / Banca: José Roberto Cury Saad / Banca: Victor Humberto Orbegoso Flores / Resumo: Atualmente, vários novos materiais estéticos são lançados no mercado odontológico destinados especificamente à confecção de restaurações diretas. Embora tais compósitos apresentem bons resultados clínicos, o que garantem ser indicados nas regiões anterior e posterior, ha a necessidade de comprovações adicionais para que se possam ser utilizados com segurança. As informações disponíveis de cada material recém introduzido ainda trazem duvidas sobre sua real composição e sobre suas propriedades físicas e mecânicas, gerando confusão para o clinico, que pode estar ciente ou não de qual resina melhor atende as necessidades de cada paciente. O conhecimento dimensional do conteúdo inorgânico dos sistemas de resinas compostas ainda e o responsável pela classificação dos mesmos e parecem estimar sobre suas propriedades mecânicas. Assim, nos propusemos a (1) estudar através de ampla e profunda revisão sistemática da literatura, a influencia das partículas inorgânicas nas propriedades físicas, químicas e mecânicas de resinas compostas e; (2) descrever a morfologia e a composição química das partículas inorgânica das resinas compostas atuais, como forma de dotar o clinico de um parâmetro de comparação entre os materiais restauradores resinosos, e de auxiliá-lo na indicação deste material mediante situação clínica. Na primeira etapa de nosso estudo, foram determinados os critérios de inclusão e exclusão, e estabelecida a estratégia de busca - palavras-chave e limites de assuntos, em varias combinações - dos estudos laboratoriais nas principais bases de dados eletrônicas (ISI - Web of Science, Medline, Biblioteca Cochrane, SciELo, Lilacs e Biblioteca Digital de Teses - Portal Capes), e outras fontes de informação. / Abstract: Currently, dozens of new aesthetic materials are launched on the dentistry market designed specifically to the confection of direct restorations. Although such composite show good clinical results, which guarantees be given in anterior and posterior regions, there is a need for additional evidence so that it can be used safely. The information available of each newly introduced material also brings questions about their real composition and on its physical and mechanical properties, creating confusion for the clinician, which may be or not aware of resin which best meets the necessities of each patient. The dimensional knowledge of the inorganic content of the composed resin systems also is responsible for the classification of the same ones and seems estimate on its mechanical properties. Thus, we proposed (1) to study through extensive and meticulous systematic review of literature, the influence of inorganic particles in the physical, chemical and mechanical properties of composite resins and; (2) to describe the morphology and chemical composition of the inorganic particles of current composite resins, as a way of giving the clinician with a parameter of comparison among the resinous restorative materials, and of assisting it in the indication of this material through of clinical situation. In the first stage of our study, the criteria of inclusion and exclusion had been determined, and established the strategy of search - keywords and limits of subjects, in some combinations - of the laboratory studies in the main electronic databases ((ISI - Web of Science, Medline, Biblioteca Cochrane, SciELo, Lilacs and Digital Library of Theses - Portal Capes), and others sources of information. Of the 138 abstracts located, only 59 were selected (most located on Pubmed) being in accordance with the pre-established criteria. / Mestre

Made available in DSpace on 2014-10-09T12:44:29Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:27Z (GMT). No. of bitstreams: 1 06872.pdf: 4167574 bytes, checksum: 52f6a850bb9e5261861d1ba84fb83a28 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Estudos prévios sugerem que a laserterapia de baixa potência (LLLT) favorece o reparo ósseo perimplantar. Este estudo avaliou a influência da LLLT sobre o reparo ósseo perimplantar in vivo em 32 coelhos Nova Zelândia submetidos à exodontia do incisivo inferior esquerdo imediatamente seguida pela inserção de um implante osseointegrável. Os animais foram distribuídos aleatoriamente em quatro grupos: um grupo controle C (animais não irradiados) e três experimentais. Estes receberam 7 sessões de terapia laser (AsGaAl, infravermelho, 830 ηm, 50mW, CW), com intervalos de 48 horas. A dose de laser por sessão variou entre os grupos EI (10 J/cm²), EII (5 J/cm²) e EIII (20J/cm²). Os animais foram mortos e os espécimes preparados histologicamente para análise da superfície de contato entre osso e implante (BIC) e da área de neoformação óssea entre as espiras (BA), em esteriologia e Microscopia Eletrônica de Varredura (MEV). A concentração de cálcio na interface do tecido ósseo com o implante foi analisada por espectrometria de raios-X por dispersão de energia (EDS). Os resultados foram analisados estatisticamente. Para MEV, as médias de BIC foram significativamente maiores para os grupos EI (977,9 μm) e EIII (1021,1 μm), comparados a EII (761,5 μm) e C (807,8 μm). Em BA, EIII (122573,7 μm²) superou os valores de neoformação dos demais grupos. O EDS para concentração de cálcio não apresentou diferença entre os grupos. A análise de BIC por meio de esteriologia mostrou valores significativamente maiores para EIII (1045,3 μm) em relação aos demais grupos. Para a BA, os grupos EI (100068,3 μm²) e EIII (103934,5 μm²) mostraram grandezas significativamente maiores. O uso da LLLT, no protocolo descrito, influenciou positivamente o reparo ósseo perimplantar com aumento do contato do tecido ósseo com o implante principalmente na dose de 20 J/cm² por sessão, bem como maior volume ósseo neoformado entre as espiras. / Previous studies suggest that the low level laser therapy (LLLT) has a favorable effect on perimplant bone healing. This study evaluates the LLLT influence over perimplant bone healing pattern in 32 New Zealand male rabbits which were subimitted to a lower incisor extraction followed by an osseointegrated implant immediated insertion. The animals were randomly divided into four groups of eight animals each: a control group C (non-irradiated animal) and three experimental groups. They received seven laser therapy sessions (GaAlAs, infrared, 830 nm, 50 mW, CW), every 48 hours. The LLLT per session dose ranged between the groups EI (dose – 10 J/cm²), EII (dose – 5 J/cm²) and EIII (dose – 20 J/cm²). The animals were killed and the specimens received histological preparation for bone implant contact analysis (BIC) and Bone Area evaluation (BA) among the implant threads, both steriology and Scanning Electron Microscopy (SEM). The calcium concentration in bone implant interface were analysed by Energy-Disperse X-Ray Spectroscopy (EDS). The results were statistically analyzed. For SEM results, the BIC’s mean were significantly higher for the irradiated groups EI (977,9 μm) and EIII (1021,1 μm) compared to EII (761,5 μm) and C (807,8 μm). For BA, EIII (122573,7 μm²) showed better values for bone neoformation compared to other groups. For EDS calcium concentration there was no significantly difference between groups. The steriology analysis showed significantly higher values for BIC in EIII (1045,3 μm) compared to the other groups. For BA, EI (100068,3 μm²) and EIII (103934,5 μm²) were significantly higher. In this laser protocol, the use of LLLT induced positively perimplantar bone repair specially due to the bone implant contact improvement (20 J/cm² per session dose), as well as, better bone area neoformation within treads.

O conhecimento da morfologia endotelial nas diferentes regiões da córnea é de suma importância para avaliação de endotélios corneanos saudáveis e doentes e de suas respostas ao uso de medicações. O objetivo do presente estudo foi descrever a morfologia do endotélio nas regiões central e periférica superior da córnea saudável de equinos, medir a área média das células pentagonais, hexagonais e heptagonais presentes nas regiões avaliadas, calcular o polimegatismo de cada tipo celular e correlacionar estes parâmetros entre os diferentes formatos celulares. Foram estudados dez equinos, machos ou fêmeas, de diferentes idades, provenientes de um abatedouro licenciado. Imagens da superfície posterior do endotélio da córnea foram obtidas com uso de microscopia eletrônica de varredura. A morfologia do endotélio de diferentes regiões da córnea foi avaliada. Além disso, foi correlacionada a variabilidade do tamanho celular médio com a morfologia endotelial. A análise estatística foi conduzida usando o teste de análise de variância (ANOVA) seguido do teste de Tukey (Post-Hoc), com nível de significância de 5%. As amostras avaliadas foram compostas em sua maioria por células hexagonais (60,5%), pentagonais (21,4%) e heptagonais (16,9%), células com quatro, oito ou nove lados compuseram 1,3%. A área celular média das células pentagonais foi 203,58 μm², das hexagonais foi 223,84 μm² e nas heptagonais foi 270,54 μm². O polimegatismo encontrado foi de 16% nas células pentagonais e hexagonais e de 20% nas heptagonais. A morfologia das células endoteliais de equinos saudáveis não diferiu entre as regiões central e periférica superior da córnea, sugerindo que a região central é representativa da região periférica. As células com sete lados apresentaram polimegatismo maior em relação às células de seis e de cinco lados. / The knowledge of the endothelial morphology in the different regions of the cornea is important for the evaluation of healthy and sick corneal endothelium and its response to drugs. In order to describe the endothelial morphology in the central and superior peripheral regions of the equines’ cornea, evaluate area from pentagonal, hexagonal and heptagonal cells present in the evaluated regions, calculate the polimegathism and correlate these parameters, two healthy corneas were collected of ten equine, male or female, of different ages. Images of the posterior surface of the corneal endothelium were taken with scanning electron microscope. The endothelial morphology was studied in the different regions of the equines’ cornea. In addition, the polimegathism and morphology was also correlated. A statistical analysis was conducted using the Analysis of Variance (ANOVA) followed by Tukey's Test (Post-Hoc), with a 5% level of significance. In the central region, the endothelium consisted of 58.8% hexagonal cells, 22.6% pentagon, 17.1% heptagonal and 1.4% cells with either four, eight or nine sides. In the superior peripheral region, 62.1% of the cells were hexagonal, 20.2% pentagon, 16.6% heptagonal and 1.1% cells with four or eight sides. The average cell area of the pentagonal cells was 210.77 ± 31.53 μm² in the central region and 196.39 ± 34.35 μm² in the superior peripheral region; in hexagonal cells, the average cell area found in the central region was 216.12 ± 37.09 μm² and 231.56 ± 34.95 μm² in the superior peripheral region; and in cells with seven sides, the average cell area was 261.76 ± 55.29 μm² in the central region and in the superior peripheral region was found 279.32 ± 52.37μm². When not considering the corneal regions, the polymegathism found was 16% in the pentagonal and hexagonal cells and 20% in the heptagonal cells. The morphology results obtained did not differ between the central and peripheral regions of the cornea, suggesting that the central region is representative of the peripheral region. The highest coefficient of variation was seen in cells with seven sides.

Magister Scientiae - MSc / The main hypothesis in this study is the development of a nanocomposite mediated amperometric biosensor for detection of hydrogen peroxide. The aim is to combine the electrochemical properties of both polyaniline and ferrocenium hexafluorophosphate into highly conductive nano composites capable of exhibiting electrochemistry in non acidic media; shuttling electrons between HRP and GCE for biosensor applications. / South Africa

Magister Chirurgiae Dentium / Dental implants are artificial fixtures that are surgically inserted into the jaws to replace missing teeth. The success of dental implant treatment is dependent on achieving successful osseointegration (Branemark et al. 2001). Drills used for implant site preparation are made of different materials such as stainless steel (SS), zirconia and ceramic. Most of them do not have sufficient cutting efficiency and wear resistance (Oliveira et al. 2012). Recently diamond-like carbon coating (DLC) has been added as a drill coating to increase the cutting efficiency, increase wear resistance and drill hardness (Batista Mends et al. 2014).