Examination of the paper insulation and copper stress braiding during stripdown of a number of Current Transformers (FMK type 400kV) has revealed the presence of dark deposits. Copper foils are often interspersed within layers of paper insulation and mineral oil found in transformer windings. The dark deposits were often found in association with these foils, affecting several layers of paper in addition to the layer in contact with the copper foil. This thesis describes the research undertaken to identify these deposits and establish a mechanism for the transportation through the paper layers. Preliminary investigation using scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray analysis (EDX) has shown these dark deposits to be copper based. X-ray photoelectron spectroscopy was used to show that the transport of the copper deposit through the paper insulation was working under the influence of a diffusion controlled process, related to Fick's law. Laboratory studies in support of work designed to eliminate the problem have shown that corrosion of copper occurs in mineral oils containing a trace of oxygen. This corrosion is non protective in character and leads to migration of copper into adjacent layers of paper. It has been shown that the transport of copper through several layers of paper can be measured by XPS and that the concentration from one paper winding to the next declines in accord with Fick's law for non-steady state diffusion. Measurements of surface concentrations by XPS correlate well with measurements made with atomic absorption spectroscopy on solutions of extracts of the contaminated paper. The laboratory measurements have allowed determination of the diffusion coefficients and activation energy for the transport process and thus give a basis for interpretation of the diffusion profiles found in the transformer in terms of time and temperature of operation. The diffusion process is temperature dependant. The results have been used to produce long term prediction curves.

Utmattningsbrott är ett återkommande problem som uppstår i borrkronor. Atlas Copco Secoroc har tidigare gjort utmattningsprovningar på fyra serier provstavar. Serierna skiljer sig från varandra på så sätt att stålet är hårt respektive mjukt härdat. Det hårdhärdade stålet är indelat i två serier. På den ena har dragprovsutmattning utförts och på den andra roterande-böj utmattning. Det samma gäller för det mjukhärdade stålet. De brottytor som uppstått vid brott av dessa provningar har undersökts, brottsförskjutningen har mätts och brottytan har analyserats med SEM. Om en icke-metallisk inneslutning (slagg) hittats som startpunkt har fyra saker undersökts. Den största diametern för inneslutningen, hur långt från ytan av staven slaggen påträffats, vilka grundämnen som inneslutningen innehåller och hur dessa grundämnen ligger i inneslutningen. För att undersöka grundämnen i inneslutningen har EDS-analys använts och för att se grundämnens fördelning har EDS-mappning använts. På grund av den begränsade tiden till detta projekt har enbart tre av de fyra provstavsserierna undersökts. Datan som har tagits fram genom undersökningarna har jämförts med data från uppdragsgivaren för att hitta samband. Nedan följer några av de slutsatser som hittades med hjälp av denna undersökning: Den kemiska sammansättningen i inneslutningarna var väldigt lika varandra. Ingen slagg skiljer sig markant från de andra. Av de inneslutningar och avtryck som observerats hade 95 % rundaktig form. Mindre inneslutningar är att föredra framför större. Anledningen är att stål med mindre inneslutningar klarade av en högre spänning och eller fler cykler innan brott sker. Inneslutningar som var i materialet hade mindre inverkan på stålets utmattningshållfasthet, än vad de på i ytan hade. Resultaten i denna undersökning har väldigt stor spridning. För att kunna dra säkra slutsatser behövs ett större underlag. Vidare utmattningsprovningar och analyser av brottytorna är att rekommendera. / Fatigue failures are a recurring problem for drill heads. Atlas Copco Secoroc has previously done fatigue failure tests on four series of sample bars. The sample bars had been hardened in two different ways. For the two first series, hardness has been increased so the material was harder, while for the other two series material was softer than the previous series. Fatigue failure tests have been done using two different methods, rotating bending fatigue and direct force fatigue testing. The fracture surface that occurred after the performed tests has been investigated. Fracture displacement has been measured. The fracture surface was examined with SEM. If a non-metallic inclusion is the starting point of the crack four different things were then investigated. The largest diameter of the inclusion, how far from the surface of the bar the slag is found, what kind of chemical elements it contains and how these elements are located through the inclusion. EDS-analysis were used to examine the chemical elements in the inclusion and EDS-mapping to see the location of the elements. Due to the limited time of this project three of the four sample bar series has been studied. The data that has been produced from these studies was then compared to the data from the costumer to find any connections. Below follows some of the conclusions that were found with the help of this study: The chemical compositions of the inclusions where very similar. No slags distinguish itself significantly from any other. 95% of the inclusions and imprints that has been observed where round shaped. Smaller inclusions are to be preferred to larger. The reason is that metal with smaller inclusions was able to cope with higher stress and or more cycles before fracture occurs. Inclusions that where found inside the material had less effect on the fatigue life for the steel then the ones on the surface. The results that has emerged from this study has a very wide distribution. To make reliable conclusions more data is needed for support. Further fatigue testing and analysis of fracture surfaces is recommended.

Aluminium sheet production is a multi-stage process in which altering processing conditions can drastically alter the size and type of second phase particles found in the final product. The properties of these second phase particles also affects deformation and annealing processes, meaning that any attempt to create a through process model would require the ability to predict both how the particles would develop in the material, and how these particles then affect the alloy moving forward. This project first focuses on gaining insight into how the particles in a model aluminium alloy change during homogenisation heat treatment and hot rolling. This has been accomplished by utilising serial block face scanning electron microscopy (SBF-SEM), a technique which allows the capture of 3D data sets at sub micron resolutions. This has allowed the populations of primary (constituent) and secondary (dispersoid) particles to be analysed at different stages of sheet production, and thus allowing the effects of homogenisation and hot rolling on particle populations to be quantified. To discover how the particles would go on to affect further processing, digital image correlation has been used to examine the localised strain in the alloy near to a selection of particle configurations. This highlighted the heterogeneity in slip behaviour within the alloy and illustrated that plumes of rotation develop near to non deformable regions. Rotation plumes have previously been modelled using a crystal plasticity model, and so further work is also presented expanding upon this model to simulate a variety of particle configurations. This has shown that in the case of single particles, local deformation is dependent on both the aspect ratio of the particle and how it is aligned to the active slip system. With the incorporation of a second particle, the interparticle spacing must also be considered.

Depuis les années 80, Les matériaux composites stratifié verre résine (SVR) ont été utilisés pour la construction des tuyaux et des réservoirs dans l'industrie chimique, y compris pour le stockage d’acides. Ce matériau composite présente une résistance supérieure à la corrosion. Cependant, des auteurs ont observé des ruptures accidentelles de réservoirs (horizontaux et verticaux) contenant des acides (chlorhydrique et sulfurique). Ces ruptures sont attribuées au mécanisme de corrosion sous contrainte (CSC). La corrosion des fibres de verre dans une solution acide est moins connue mais reste très importante. Ce mécanisme de corrosion, appelée désalcalinisation de la fibre peut provoquer la fissuration de la fibre de verre.Des essais de corrosion avec de l’acide chlorhydrique (37%) ont été effectués sur éprouvette SVR. Ces essais de corrosion ont été suivis par émission acoustique. Les observations au microscope électroniques à balayage (MEB) et les analyses physico-chimiques confirment la corrosion de fibres de verre dans une solution de HCl. L’utilisation de la micro-tomographie nous montre que cette technique permet d’avoir une information sur la profondeur d’attaque du matériau.Une approche statistique est utilisée pour caractériser les paramètres de la salve d’émission acoustique afin de les séparer. Le Clustering est fait en utilisant la méthode des k-moyennes. Trois classes d’émission acoustique distinctes ont ainsi été identifiées. L’analyse croisée de l’émission acoustique et des observations ont permis de relier les classes observées aux conséquences de la corrosion du SVR. / Since the 1980, Glass Reinforced Plastic (GRP) has been used for construction of pipes and tanks in the chemical industry, including the storage of mineral acids. This composite material offers superior and cost effective corrosion resistance. However, authors found accidental breakage of tanks (horizontal and vertical) containing mineral acids (hydrochloric and sulphuric). These failures are attributed to environmental stress-corrosion cracking (ESCC) mechanism. The corrosion of glass fibers in mineral acid solution is less known but very important. The mechanism of the corrosion, called leaching, is thought to induce tensile stresses in the surface of the glass. These stresses could be large enough to cause cracking of the fiber glass.Corrosion tests have been performed on GRP specimen. Aggressive environments used are hydrochloric acid (37%) This environment is known to react with E-glass. Corrosion tests have been monitored by acoustic emission.SEM observations and physicochemical analysis confirm the corrosion of glass fibers in HCl solution. The use of micro - tomography allows to have information on the depth of degradation of the material.Statistical approaches are used to characterize hit’s parameters. Clustering is made by using k-mean’s method. Three distinct acoustic emission classes are identified. Thanks to SEM observations and acoustic emission results, clusters can be assigned to the appearance of minor defects in the material.

Electrical trees are micrometre-size tubular channels of degradation in high voltage polymeric insulation, a precursor to failure of electrical power plant. Hence, electrical trees critically affect the reliability of power systems and the performance of new insulation designs. Imaging laboratory-grown electrical trees has been an important tool for studying how trees develop. Commonly, electrical trees prepared in transparent or translucent polymers are imaged using traditional optical methods. Consequently, most of the analysis has been based on two-dimensional (2D) images of trees, thus, valuable information may be lost. However, electrical trees are complex interconnected structures that require a tree-dimensional (3D) approach for more complete analysis. This thesis investigates a method for imaging and analysis of electrical trees to characterise their 3D structure and provide a platform for further modelling. Laboratory created electrical trees were imaged using X-ray Computed Tomography (XCT) and Serial Block-Face Scanning Electron Microscopy (SBFSEM), 3D imaging techniques that provide sub-micrometre spatial resolution. Virtual replicas of the trees, which are the 3D geometrical models representing the real electrical trees, were generated and new indices to characterise the 3D structure of electrical trees were developed. These parameters were indicative of differences in tree growth and thus, they can be used to investigate patterns and classify the structure of electrical trees. The progression of the tree was analysed using cross-sections of the tree that are orthogonal to the growth: the number of tree channels and area covered by them were measured. The fractal dimension of the tree was calculated from the 3D model and from the 2D projections, the latter being lower for all the tree-type structures studied. Parameters from the skeleton of the tree such as number of nodes, segment length, tortuosity and branch angle were measured. Most of the mean segment lengths ranged 6-13 µm, which is in accordance to the 10µm proposed by various tree-growth models. The capabilities of XCT and SBFSEM imaging techniques were evaluated in their application to electrical trees. Bush and branch trees, including early-growth electrical trees (of length 20-40 µm), were analysed and compared using the comprehensive tool of visualisation and characterisation developed. A two-stage tree-growth experiment was conducted to analyse the progression and development of tree branches using XCT: tree channels after the second stage of growth were wider than after the first, while the fractal dimension remained the same. The capabilities of XCT and SBFSEM were tested for imaging electrical trees in optically-opaque materials such as micro and nano-filled epoxy compounds. The general structure of trees in epoxy filled up to 20 wt% micro-silica was observed using both techniques. The use of a virtual replica as the 3D geometrical model for the simulation of the electric field distribution using Finite Element Analysis (FEA) was preliminary explored. A combination of the imaging techniques is proposed for a more complete structural analysis of trees. It is believed that a great impact towards understanding electrical treeing will be achieved using the 3D technical platform developed in this thesis.

M.Sc. / Donor-acceptor (D-A) systems consist of a donor covalently or non-covalently linked to an acceptor. The simplest D–A system consists of a donor linked to an acceptor and is called a dyad system. Photoactive dyad systems are molecular devices designed to perform through the separation of charge separation states and the conversion of solar energy to chemical energy in analogy to photosynthesis.1 These dyad systems consist of a donor which is usually a chromophore and an acceptor. The design of these systems is guided to mimic photo-induced electron transfer (PET) and charge separation (CS), which are fundamental processes of photosynthesis. In nature, photosynthetic units are often built from dyads consisting of pigments like chlorophyll (donors), non–covalently linked to quinones, (acceptors). The donor harvests light energy and transfers the energy to the nearby pigment molecules until it eventually reaches a special region of the chlorophyll macrocycle called the reaction centre where this light energy is then converted to electrochemical energy. Photoactive dyad systems act as artificial photosynthetic models as they reproduce photo–induced electron transfer and charge separation of natural photosynthesis. In this project, dyad systems were made by covalently linking zinc pheophorbide, a modified chlorophyll derivative to double–walled carbon nanotubes (DWCNTs). Zinc pheophorbide acts as the donor and DWCNTs as the acceptors. Chlorophyll was modified by cutting the phytol chain and inserting zinc as the central metal to yield zinc pheophorbide. This derivative is stable against irradiation, has a good range of acceptor wavelength and is also a good light harvester. DWCNTs are one dimensional nanowires with two concentric tubes. They readily accept electrons because they have an extended π electron system. These electrons are then transported efficiently under ballistic conditions. DWCNTs were synthesised by catalytic chemical vapour deposition (CCVD) of methane over Mg0.99Co0.075Mo0.025O catalyst. In dyad system 1, amidated zinc pheophorbide molecules were covalently attached to oxidised DWCNTs in the presence of N–ethyl–N’–(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) \ and N–hydroxysuccinnimide (NHS) as a catalysts. Dyad system 2 was synthesized by attaching zinc pheophorbide molecules to amidated DWCNTs using the same catalysts.

A Physalis peruviana Linnaeus é uma fruta considerada exótica que possui elevado custo de comercialização, principalmente nos mercados internacionais. Suas propriedades nutracêuticas e o aumento da sua produtividade no Estado do Rio Grande do Sul, associados à sua elevada perecibilidade definiram o objetivo deste trabalho: estudar o processo de transferência de massa durante a desidratação osmótica de physalis. Diversos trabalhos que avaliam as propriedades dos compostos bioativos da physalis através de ensaios in vitro e in vivo estão disponíveis na literatura, no entanto, há uma carência de informações a respeito de processos de industrialização desta fruta. Neste trabalho foi realizada a desidratação osmótica da physalis avaliando os efeitos da temperatura (variando de 40 a 70 C), da concentração da solução osmótica de sacarose (variando de 40 a 70 g por 100 g de solução) e da interação dessas variáveis através de planejamento experimental 22 com três repetições no ponto central (em duplicata). Análises de umidade (método gravimétrico), sólidos solúveis (refratômetro), açúcares totais (cromatografia líquida de alta eficiência) foram realizadas ao longo do processo de desidratação osmótica, enquanto que, as análises de carotenoides totais (espectrofotômetro), atividade de água (método higrométrico) e cor (escala CIELAB) foram realizadas para a fruta in natura e após 10 horas de processamento. Adicionalmente, testes utilizando uma sonda de ultrassom (frequência de 20 KHz, amplitude de 80 % durante 30 minutos) como pré-tratamento ao processo de desidratação osmótica foram realizados, a fim de aumentar a permeabilidade da casca cerosa desta fruta. Além disso, foram realizadas análises de atividade de água e da viscosidade das soluções osmóticas utilizadas neste trabalho. Os resultados mostraram que a utilização da sonda de ultrassom como pré-tratamento não apresentou diferenças estatisticamente significativas para nenhum dos parâmetros estudados, dentro da faixa de temperatura e concentração avaliadas. O modelo de Rastogi & Raghavarao mostrou-se adequado para a determinação do conteúdo de umidade e de sacarose no equilíbrio, assim como a utilização do modelo de difusão da Segunda Lei de Fick para a determinação da difusividade mássica efetiva da água e da sacarose na physalis usando os cinco primeiros termos da série. A difusividade mássica efetiva da água variou de 2,44 - 7,60 x 10-10 m2 s-1, enquanto que a da sacarose variou de 2,13 - 3,20 x 10-10 m2 s-1. Dentre todas as condições estudadas no planejamento experimental, o processo de desidratação osmótica mostrou-se mais eficiente quando realizado na temperatura de 70 C e concentração da solução osmótica de 70 g por 100 g de solução. Nessa condição experimental houve uma elevada perda de água (aproximadamente 83 %), além de uma redução estatisticamente significativa na atividade de água da fruta (passando de 0,979 para 0,872 após 10 horas), no entanto, ocorreu a maior perda de carotenoides totais (aproximadamente 50 %). Nessa condição experimental, a matriz do tecido da physalis sofreu alterações que foram comprovadas através da análise microestrutural realizada por Microscopia Eletrônica de Varredura (MEV). Adicionalmente, verificou-se que nenhum dos tratamentos realizados promoveu modificações visualmente perceptíveis na diferença global de cor (ΔE*) devido ao processo de desidratação osmótica. / Physalis peruviana Linnaeus is considered to be an exotic fruit, with a high cost of commercialization, especially in international markets. Its nutraceutical properties and increased productivity in the state of Rio Grande do Sul, associated with its high perishability defined the goal of this work is the following: to study the process of mass transfer during the osmotic dehydration of physalis. It is noteworthy that several studies have evaluated the properties of the bioactive compounds of physalis both in vitro and in vivo; however, there is a shortage of information in the literature regarding the industrialization of physalis. In this work the osmotic dehydration of physalis was carried out evaluating the effects of temperature (ranging from 40 to 70 °C), osmotic sucrose solution concentration (ranging from 40 to 70 g per 100 g solution) and the interaction of these variables by a 22 experimental design, with three replicates at the center point (in duplicate). Analyses of moisture content (gravimetric method), soluble solids (refractometer) and total sugars (high performance liquid chromatography - HPLC) were performed along the osmotic dehydration process. Content of total carotenoids (spectrophotometer), water activity (hygrometric method) and color (CIELAB scale) were analyzed for the fresh fruit and after 10 hours of processing. In addition, tests using an ultrasound probe (frequency 20 kHz, amplitude of 80 % for 30 minutes) as a pretreatment for the process of osmotic dehydration were performed to increase the permeability of the waxy skin of this fruit. Furthermore, analyses of the water activity and viscosity of the osmotic solutions used were carried out. The results show that the use of the ultrasound probe as a pre-treatment did not yield statistically significant differences for any of the parameters studied within the temperature range at the concentrations assessed. The model of Rastogi & Raghavarao proved to be suitable for the determination of equilibrium content; Fick's Second Law was satisfactorily used to determine the effective diffusivity of water and sucrose for a spherical geometry. Thus, the effective diffusivity of water was calculated and ranged from 2.44 to 7.60 x 10-10 m2 s-1, while that of sucrose ranged from 2.13 to 3.20 x 10-10 m2 s-1. Among all conditions studied in the experimental design, the osmotic dehydration process was more efficient when performed at a temperature of 70 °C and an osmotic solution concentration of 70 g per 100 g of solution. In these conditions, there was a high water loss (approximately 83 %) and a statistically significant reduction in the water activity of this fruit (from 0.979 to 0.872 after 10 hours); however, the greatest loss of total carotenoids (approximately 50 %) was observed. Under this experimental condition, the tissue matrix of physalis suffered structural changes, as proven through Scanning Electron Microscopy (SEM) analysis. Additionally, it was found that none of the treatments performed promoted visually perceptible changes in the overall color difference (ΔE*) due to processing.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-15T12:57:52Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Mestrado, Rocha,APS.pdf: 1946617 bytes, checksum: b6dc0fb29dac8660c791c1a05c3de947 (MD5) / Made available in DSpace on 2016-04-15T12:57:52Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Mestrado, Rocha,APS.pdf: 1946617 bytes, checksum: b6dc0fb29dac8660c791c1a05c3de947 (MD5) Previous issue date: 2015-02-20 / CAPEs / Piedra preta é uma micose superficial assintomática, caracterizada pela formação de nódulos rígidos e enegrecidos localizados ao longo do fio capilar. É uma micose considerada rara, inócua, podendo acometer tanto o gênero feminino quanto o masculino em qualquer faixa etária. Piedraia hortae, agente etiológico desta micose, é um fungo filamentoso, demáceo que produz o pigmento melanina, caracterizando uma coloração enegrecida na parede celular e nas estruturas fúngicas. Este pigmento, por sua vez, é caracterizado como um potente fator de virulência, favorecendo, desse modo, seu potencial em causar parasitismo no cabelo. Na literatura, não há referências citando que outros fungos demáceos, que formam ascostroma, ascos e ascosporos, semelhantes ao P. hortae, possam ser agente etiológico dessa feohifomicose. Assim, o objetivo desse trabalho foi avaliar a capacidade de fungos demáceos de formarem nódulos na porção extrafolicular de fios de cabelo humano, semelhantes aos da piedra preta. Foram obtidos onze isolados de fungos demáceos, sendo dez da Coleção de Cultura Micoteca URM, UFPE, os quais estavam preservados sob óleo mineral e posteriormente semeados em meio Àgar Batata Dextrose para estimulação do crescimento; e um isolado proveniente do Laboratório de Micologia Médica. Foram preparadas suspensões dos isolados dos fungos demáceos em 2,0 ml de água destilada esterilizada, ajustada para concentração final de 106 células/mL. Em seguida, vertidos separadamente 0,5 mL de cada suspensão sobre os fios de cabelo contidos nas placas de Petri previamente esterilizada e mantidas a temperatura de 28°C e 37°C. O experimento foi conduzido através de observações macroscópicas e microscópicas dos cabelos durante 40 dias e acompanhado em intervalo de 5 dias. Dois isolados (970 e 3334) mostraram um elevado potencial capaz de causar infecção no fio capilar. Entretanto, oito isolados apresentaram apenas uma colonização. Exophiala dermatitidis e Cladosporium tenuissimo foram capazes de formar nódulos semelhantes ao da piedra preta, porém estruturas de reprodução como ascostroma, ascos e ascosporos, não foram vizualizadas.Todavia, podemos inferir que esses fungos apresentam um potencial capaz de parasitar os fios de cabelo, degradando e destruindo a queratina e os componentes cutiulares, sendo o potente agente de tricomicose. / Black piedra is a superficial mycosis asymptomatic, characterized by the formation of hard lumps and blackened located along the capillary yarn. It is a mycosis considered rare, innocuous and can affect both the female and the male at any age. Piedraia hortae, the etiologic agent of this mycosis, is a filamentous fungus, dematiaceous that making the pigment melanin, featuring a blackish color in the cell wall and the fungal structures. This pigment, in turn, is characterized as a potent virulence factor, facilitating there by the potential to cause parasitic hair. In the literature, there are no references citing that other demáceos fungi that form ascostroma, asci and ascospores, similar to P. hortae, may be etiologic agent of this phaeohyphomycosis. The objective of this paper is to demáceos fungal ability to form nodules in extrafollicular portion of human hair, similar to those of black piedra. Eleven isolates of fungi demáceos, obtained of the Culture Collection URM, UFPE, which were preserved under mineral oil and then plated on potato dextrose agar medium for growth promotion; and one isolated from the Medical Mycology Laboratory. Fungal isolates demáceos suspensions were prepared in 2.0 ml of sterile distilled water, adjusted to a final concentration of 106cells / ml. Then separately poured into 0.5 mL of each suspension over the strands of hair contained in the previously sterile Petri dishes and kept at 28 °C and 37 °C. The experiment was conducted by macroscopic and microscopic observations of the hair for 40 days and monitoring in the range of 5 days. Two isolates (970 and 3334) showed a high potential capable of causing infection in the capillary. However, eight isolates showed only colonization. Exophiala dermatitidis and Cladosporium tenuissimo was capable of forming nodules were similar to those of black piedra; however ascostroma structures such as playback, asci and ascosporos were not displayed. However, we can infer that these fungi have the potential able to parasitize the hairs, degrading and destroying the keratin and cuticulares components, the powerful Trichomycosis agent.

Orientador: Carlos Kenichi Suzuki / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-27T06:45:12Z (GMT). No. of bitstreams: 1 Schenkel_EgontAlexandre_M.pdf: 11831501 bytes, checksum: 100fb5f4a5379818f466b361ab913849 (MD5) Previous issue date: 2015 / Resumo: Neste trabalho foi apresentada uma metodologia para obtenção de nanocristais de quartzo a partir do processo de moagem em moinho de bolas rotativas, com posterior separação granulométrica lançando mão da decantação de partículas de maior densidade em meio aquoso. Foram estudadas duas fontes de quartzo natural com diferentes origens geológicas, uma proveniente de Soledade-PB e outra de Belmonte-BA. Esses minerais foram processados e seu produto foi caracterizado utilizando técnicas de difração de raios-X (DRX) e microscopia eletrônica de varredura (MEV). Como resultado, foram obtidas nanopartículas com morfologia irregular, com parcial perda de cristalinidade e tamanho médio em torno de 100 nm. Foram também efetuados testes de obtenção desse material em escala industrial. Como resultado, foram obtidas partículas de quartzo submicrométricas (~300 nm) com propriedades estruturais similares às obtidas em laboratório / Abstract: This work presents a methodology to obtaining quartz nanocrystals from the ball milling and granulometric particle separation in an aqueous solution. Two sources of natural quartz were studied with different geological origins, one from Soledad-PB and another of Belmonte-BA. These minerals were processed and their product was characterized using X-Ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. As a result, nanoparticles were obtained with irregular morphology, partial loss of crystallinity and average size around 100 nm. Tests have also been made to obtain this material on industrial scale. As a result, submicron quartz particles were obtained (~ 300 nm) with similar structural properties to those obtained in the laboratory / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Orientador: Julian Martínez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-27T11:44:01Z (GMT). No. of bitstreams: 1 Barrales_FranciscoManuel_M.pdf: 2768336 bytes, checksum: 142a36d90affeb4da8cdcb77e0d9bd5e (MD5) Previous issue date: 2015 / Resumo: O presente trabalho teve como principal objetivo avaliar a influência da aplicação de ultrassom na extração de óleo de semente de maracujá com CO2 supercrítico, focando no rendimento da extração, na cinética do processo, conteúdo de tocoferóis e tocotrienóis, perfil de ácidos graxos, e atividade sequestrante do radical DPPH do óleo, usando como matéria-prima sementes de maracujá misturadas com polpa provenientes da indústria de processamento da fruta. Com esse intuito, a metodologia de superfície de resposta foi empregada, partindo como base de um planejamento experimental de tipo composto central para três fatores. Os fatores avaliados foram temperatura (38; 40; 45; 50 e 52°C), pressão (13; 16; 21; 26 e 29 MPa) e potência de ultrassom (0; 160; 400; 640 e 800 W). Os extratos obtidos apresentaram alto porcentagem de ácidos graxos poli-insaturados (aproximadamente 67%) e teor de tocoferóis e tocotrienóis (entre 60 e 90 mg/100g óleo), atividade sequestrante do radical DPPH (entre 1,8 e 2,6 mg TE/g óleo) que demonstrou correlação com o conteúdo total de tocoferóis e tocotrienóis (r = +0,872). A análise de polifenóis totais não conseguiu detectar a presença de polifenóis nos extratos. A aplicação de ultrassom na menor potência (160 W) resultou vantajosa, gerando incrementos de até 29% no rendimento de SFE. Este efeito foi registrado na temperatura de 40 °C e pressão de 16 MPa. O modelo de Sovová (1994) mostrou-se adequado para descrever o comportamento da cinética de extração, permitindo avaliar os parâmetros ajustados. Quando foi evidenciado grande incremento no rendimento da SFE, decorrente da aplicação do ultrassom, os parâmetros cinéticos foram modificados, sendo o tempo da etapa CER maior, junto com o coeficiente de transferência de massa da fase fluida, houve diminuição da proporção de extrato de difícil acesso. As imagens obtidas por microscopia eletrônica de varredura com fonte de emissão de campo (FESEM) demonstraram efeitos de atrito e menor tamanho de partículas quando o ultrassom foi aplicado / Abstract: The present work had as main objective the evaluation of the effect of the application of ultrasound in the extraction of passion fruit seed oil using supercritical CO2, on the global extraction yield, the process kinetics, the tocopherol and tocotrienol content and DPPH radical scavenging activity, using as raw material passion fruit seeds mixed with pulp, a byproduct of the pulp processing industry. To accomplish that, the response surface methodology was used. The evaluated factors were: temperature (38; 40; 45; 50 and 52 °C), pressure (13; 16; 21; 26 and 29 MPa) and ultrasound power (0; 160; 640 and 800 W). Fatty acids composition, total polyphenolic content, identification and quantification of tocopherols and tocotrienols and the antioxidant activity were evaluated on the extracts, which resulted rich in polyunsaturated fatty acids (about 67%) and tocopherols and tocotrienols (between 60 and 90 mg/100g oil), of high antioxidant activity (between 1,8 to 2,6 mgTE/g oil) that shown correlation with the tocopherol and tocotrienol total content (r = +0,872). The total polyphenol analysis was not able to detect the presence of polyphenols in the extracts. The application of low power ultrasound (160 W) resulted advantageous; the SFE global yield improvement achieved 29%. This effect was registered at a temperature of 40 °C and pressure of 16 MPa. The model of Sovová (1994) was adequate to describe the extraction kinetics behavior, and it was possible to evaluate the adjusted parameters. When a great increase of SFE yield was achieved due to the ultrasound application, the kinetic parameters were modified, being the CER time and the fluid phase mass transfer coefficient increased, also showing reduction of solute ratio inside the cells. . The images obtained by field emission scanning electron microscopy (FESEM) demonstrated mechanical damage effects and smaller particle size when ultrasound was applied / Mestrado / Engenharia de Alimentos / Mestre em Engenharia de Alimentos