The RHEA Spectrograph is a single-mode echelle spectrograph designed to be a replicable and cost effective method of undertaking precision radial velocity measurements. Two versions of RHEA currently exist, one located at the Australian National University in Canberra, Australia (450 - 600nm wavelength range), and another located at the Subaru Telescope in Hawaii, USA (600 - 800 nm wavelength range). Both instruments have a novel fibre feed consisting of an integral field unit injecting light into a 2D grid of single mode fibres. This grid of fibres is then reformatted into a 1D array at the input of the spectrograph (consisting of the science fibres and a reference fibre capable of receiving a white-light or xenon reference source for simultaneous calibration). The use of single mode fibres frees RHEA from the issue of modal noise and significantly reduces the size of the optics used. In addition to increasing the overall light throughput of the system, the integral field unit allows for cutting edge science goals to be achieved when operating behind the 8.2 m Subaru Telescope and the SCExAO adaptive optics system. These include, but are not limited to: resolved stellar photospheres; resolved protoplanetary disk structures; resolved Mira shocks, dust and winds; and sub-arcsecond companions. We present details and results of early tests of RHEA Subaru and progress towards the stated science goals.

Bio-basedcomposites are being increasingly used in applications where weight saving,and environmental friendliness is as important as structural performance. Obviously, bio-based materials have their limitations regarding durability and stability of the properties,but their potential in use for advanced applications can be expanded if they were functionalized and considered beyond their structural performance. Multifunctionalityincomposites can be achieved by modifyingeither of the composite constituents at different levelsso that they can perform energy-associated roles besides their structural reinforcement in the system. For the fibers, this can be done at the microscale by altering theirmicrostructure during spinning process or by applying functional coatings. As for the matrix, it is usually done by incorporating additives that can impart the required characteristics to the matrix. The nano-sized additives that mightbe considered for this objective are graphene and carbon nano-tubes. A big challenge with such materials is the difficulty to reachthe dispersionstate necessary for formation ofstable network to overcome the percolation threshold for conductivity. However, once the network is formed, the composite can have improved mechanical performance together with one or more of the added functionalities such as barrier capabilities,thermal and/or electrical conductivities or electromagnetic interference ability. Enormous work has been done to achieve the functionality incomposites produced with special care in laboratories. However, when it comes to mass production, it is both cost and energy inefficient to use tedious,complex methods for the manufacturing. Hence there is a need to investigate the potential of using scalable and industrial-relevant techniques and materials with acceptable compromise between cost and properties. The work presented in this thesis is performedwithin two projects aiming to achieve functional composites based on natural and man-made cellulosic fibers suitable for industrial upscaling. Conductive Regenerated Cellulose Fibers (RCFs) were produced by coating them with copper by electroless coating process using commercial materials. On the other hand, commercial masterbatches based on Graphene Nano-Platelets (GNPs) were used to produce wood polymer composites (WPC) with added multifunctionality by melt extrusion process. The process is one of the conventional methods used inpolymerproductionand needsno modifications for processingfunctional composites. Both materials together can be used to produce hybrid functional composites. The incorporation of the GNP into HDPE has resulted in improvement in the mechanical propertiesof polymer as well as composite reinforced with wood fibers. Stiffness has increased to a large extent while effect on the strength was less pronounced(>100% and 18% for stiffness and strength at 15%GNP loading). The enhancement of thermal conductivityat higher graphene loadingswas also observed. Moreover, time-dependent response of the polymer has also been affected and the addition of GNP has resulted in reduced viscoplastic strains and improved creep behavior. The copper-coated cellulose fibers showed a significant increasein electrical conductivity(<1Ω/50mm of coated samples) and a potential in use as sensor materials. However, these results come with the cost of reduction in mechanical properties of fibers (10% and 70% for tensile stiffness and strength, respectively) due to theeffect ofchemicals involved in the process.

A tubulização representa uma possível alternativa para reparo de lesões de nervos periféricos, por permitir a aplicação local de fatores de crescimento e neurorregenerativos assim como por facilitar o estudo dos mecanismos de ação relacionados à regeneração das fibras nervosas. O objetivo do presente estudo foi verificar se há crescimento de fibras amielínicas no nervo fibular comum de ratas Wistar adultas após a tubulização látero-terminal (TLT) sem a utilização de indutores de crescimento, através de análise morfológica e morfométrica das referidas fibras. Para tanto, o nervo fibular comum direito foi seccionado a 3 mm da sua emergência, o coto proximal sepultado e suturado na musculatura adjacente e um tubo de silicone (6 mm) interposto entre o coto distal do fibular e a lateral do nervo tibial (grupo TLT). O controle usado foi o segmento distal esquerdo do nervo fibular (grupo GN). Setenta dias após, foram realizados cortes semifinos e ultrafinos para análise de aspectos morfológicos e morfométricos através de microscopia de luz e microscopia eletrônica de transmissão (MET). Houve evidente brotamento axonal de fibras amielínicas, que cresceram a partir do nervo tibial intacto no grupo TLT em comparação ao grupo GN, sendo que o número total de axônios amielínicos foi similar nos dois grupos. Estudo morfométrico evidenciou diferenças significativas (p<=0,05) em relação à maior densidade de axônios amielínicos regenerados e em relação ao diâmetro mínimo axonal. No presente estudo os axônios amielínicos no nervo receptor, usando o modelo da TLT, foram quantificados. Esse modelo poderá ser útil e importante para estudo da plasticidade do sistema nervoso periférico. / Side-to-end tubulisation is a model recently developed in our laboratory to study nerve plasticity. In this model, collateral sprouting of fibers grow from intact donor nerve fibers to the distal stump of a receptor nerve. The objective of the present study was to study unmyelinated fibers using this model. Adults female Wistar rats were used and morphological and morphometric analysis were done. The fibular common nerve was sectioned 3 mm from its origin. The proximal stump was buried and sutured in the adjacent musculature. A silicone tube (6 mm) was fixed on the adjacent lateral portion of the intact tibial nerve and the fibular common nerve distal stump was sutured in the other extremity of the tube (SET group). The left fibular common nerve distal segment was used as control. Semithin and ultrathin sections were obtained and studied using light and transmission electron microscopy. Seventy days after, there was profuse axonal sprouting of unmyelinated fibers that grew from the nerve tibial, reaching the same number of axons when compared with the controls. In the present study unmyelinated axons in the receptor nerve using SET were quantified. SET is an important tool to study plasticity of peripheral nerve fibers.

<p>To fully optimize devices for solar energy conversion, a comprehensive understanding of how excitons migrate in materials for solar cell devices is crucial. Understanding the mechanisms behind exciton diffusion and energy transfer will enable the fabrication of highly efficient devices. However to thoroughly study exciton properties, techniques implementing high spatial (nm sizes) and temporal (fs time scales) resolution is required. Herein, we utilize transient absorption microscopy (TAM) with 50 nm spatial resolution and 200 fs temporal resolution to elucidate exciton diffusion in polymeric materials for solar energy conversion.</p> <p>While organic devices are inexpensive and require simpler fabrication procedures than inorganic materials, their device efficiencies often suffer due to their semi-crystalline nature, lending to short diffusion lengths which lead to trap sites and inevitably recombination. It has been demonstrated that achieving long-range exciton diffusion lengths is possible through coherence effects. Coherence can be found in an intermediate electronic coupling region where delocalization and localization compete.</p> <p>To exploit coherence effects, we study polymeric systems in which polymer chains are highly aligned via simple and scalable procedures; semiconducting fibers and solution coated films. In studying the fiber, we first implement polarized photoluminesce (PL) to determine optical ansitropy. From the polarized PL and PL images, it is observed that emission intensities are largest when probing along the transition dipole moment of the polymer. This suggests a type of Förester Resonance Energy Transfer mechanism in which excitons hop from one polymer chain to another.</p> <p>Solution coated polymer films are also studied to understand exciton diffusion as a function of deposition methods. By varying the solution concentration as well as coating rate, we are able to tune the morphology of the film. We observe a strong dependence between diffusion constant and deposition parameters, with diffusion constants of <i>ca.</i> 9, 13 and 33 cm²/s for three different films. The results obtained in this thesis are preliminary steps in an effort to elucidate energy transfer mechanisms and rates.</p><br>

Le béton est le matériau de construction le plus utilisé dans le monde. Des fibres sont introduites pour le renforcement du béton de structure. Jusqu'à présent, les fibres utilisées sont généralement des fibres métalliques ou synthétiques (par exemple les fibres de polypropylène).Dans notre étude, nous nous sommes intéressés au remplacement des fibres synthétique (le polypropylène dans notre cas), par des fibres végétales naturelles à s'avoir l'alfa, une graminée méditerranéenne.Nous avons formulé et confectionné des éprouvettes de différents types de bétons renforcés aux fibres d'alfa ainsi que deux bétons témoins, le premier ordinaire et le second renforcé de fibres de polypropylène.La caractérisation a montré que les dosages en fibres d'alfa les plus performants sont ceux de 1% et 1,5% de fibres d'alfa, qui ont donnés des résistances mécaniques comparables à celles des bétons ordinaires et des bétons renforcés au polypropylène.Les tests de durabilité (attaque sulfatique externe et élévation de température) ont montré que le béton renforcé à 1% de fibre d'alfa est celui dont les résultats se rapprochent de ceux des bétons ordinaires. Le béton à 1% de fibres d'alfa constitue donc le béton optimal.L'analyse environnementale a montré que les fibres d'alfa sont beaucoup moins impactantes sur l'environnement que celles de polypropylènes quant-à l’épuisement des énergies fossiles, le changement climatique (lié à l’émission de gaz à effet de serre, parmi lesquels le CO2), l’émission atmosphérique de particules, l’écotoxicité marine et l’oxydation photochimique. / Concrete is the most used building material in the world. In order to reinforce struture concretes, different kinds of fibres are added among which metallic and synthetic (e.g. polypropylene) fibres.In our study, we have replaced polypropylene fibres by natural vegetal fibres of alfa, a grass commonly found aroud the Mediterranean.We have prepared 3 kinds of concrete : alfa-reinforced concrete (with various amounts of alfa fibres), polypropylene-reinforced concrete and ordinary concrete used as references.Characterization showed that the best amounts of alfa fibres are 1 and 1.5 %, that gave a mechanical behaviour close to that of ordinary and polypropylene-concrete.Durability tests (sulfatic attack and high temperature) showed that the concrete reinforced with 1% of alfa fibres gives the closest results compared to ordinary concrete. Concrete with 1% of alfa fibres is hence the best concrete.Environmental analyses showed that alfa fibres generate far less impacts than polypropylene fibres as regards fossil fuel depletion, climate change (linked with emissions of greenhouse gases among which CO2), atmospheric emission of particles, marine ecotoxicity and photochemical oxydation.

A dissertation submitted to the Faculty of Engineering and the built environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Engineering Johannesburg, October 2017 / An investigation was carried out to determine the effect of the addition of clay on the mechanical properties of a Natural Fibre Composite consisting of a polypropylene matrix with kenaf fibre reinforcement. The kenaf fibres were treated using various chemical treatments to improve the strength of the composites manufactured. Four treatments using different 3-mercaptopropyltrimethoxy silane (MPS) concentrations were investigated to determine which treatment resulted in the best mechanical properties. [Abbreviated Abstract. Open document to view full version] / MT 2018

Le vieillissement s’accompagne de changements de la perception de la douleur, avec notamment des modifications des seuils de douleur. L’objectif de ce travail de thèse était de déterminer les mécanismes sous-jacents à ces changements. Nous nous sommes basés sur l’étude de deux indicateurs : des données psychophysiques (i.e., jugements perceptifs) et des mesures électrophysiologiques. Nos premiers tests ont confirmé une diminution de la douleur perçue chez les séniors. Une série de 4 expérimentations nous a ensuite permis de montrer que l'augmentation du seuil de douleur chez les séniors avait à la fois une origine périphérique (i.e., atteinte des fibres sensorielles) et centrale (i.e., modification cérébrale). Au niveau périphérique, nous avons montré que seules les fibres myélinisées (fibres A delta) semblent altérées par le vieillissement. Au niveau central, nos résultats vont dans le sens d'un seuil de douleur augmenté en raison d'un déficit attentionnel chez les séniors. / Non-pathological ageing is often associated with changes in pain perception and especially with changes in pain thresholds. The aim of this thesis was to determine the underlying mechanisms of these changes. We analyzed two complementary indicators: psychophysical data, by the means of perceptual judgments, and electrophysiological measurements. Our first tests confirmed a decrease of older subjects' perceived pain, compared to that of younger adults. A series of 4 experiments further allowed us to show that the increase in older adults' pain threshold has both a peripheral (i.e., impairment of peripheral sensory fibers) and a central (i.e., modifications at a cerebral level) origin. At the peripheral level, we found that only myelinated fibers (i.e., A-delta fibers) seem to be affected by ageing. At a central level, our results indicate that the increase in pain thresholds is due to difficulties in allocating attentional resources to the stimulation in the elderly.

As indústrias beneficiadoras de frutas são responsáveis por gerar grandes quantidades de resíduos, entre eles, os do maracujá. A polpa do maracujá é um dos principais produtos comercializados a partir da fruta, sendo as cascas e sementes os subprodutos resultantes de seu processamento. O objetivo deste trabalho foi desenvolver iogurte com adição de polpa e farinha de maracujá elaborada a partir dos subprodutos da industrialização da fruta. No total, foram avaliadas sete amostras de iogurte dentre as quais cinco apresentavam em sua composição a farinha de maracujá. Foram realizadas análises físico-químicas, microbiológicas, verificação de resíduos de agrotóxicos, teste de aceitação sensorial, verificação da intenção de compra, análise descritiva quantitativa (ADQ), estimativa da vida útil e elaboração dos rótulos dos produtos. Todos os iogurtes adicionados de farinha apresentaram elevados teores de fibra alimentar. Não foram detectados resíduos de agrotóxicos nas amostras do subproduto do maracujá. Observou-se que a incorporação da farinha de maracujá apresentou efeitos positivos na viscosidade e teor de minerais do iogurte, e negativos para aspectos como cor e pH. Verificou-se maior aceitação dos provadores para o iogurte sem adição de farinha. No entanto, o iogurte com baixa concentração do ingrediente (iogurte 2%) também apresentou aceitação satisfatória e intenção de compra relevante. A partir da ADQ, comprovou-se que a adição da polpa e da farinha de maracujá influenciou o perfil sensorial das amostras de iogurte, sendo que, os tratamentos com 2% e 4% de farinha, foram os que apresentaram maiores notas para a maioria dos atributos desejáveis para um iogurte sabor maracujá enriquecido com fibras. O tempo de vida útil do produto foi estimado em 21 dias, sendo que durante o armazenamento, observou-se elevação das taxas de sinérese, crescimento de fungos e leveduras, decréscimo do pH e do número de bactérias láticas viáveis nas amostras. Levando em consideração os dados obtidos, o iogurte com adição de 2% de farinha de maracujá foi considerado o produto mais viável para elaboração / The fruit-processing industries are responsible for generating large quantities of residues, like passion fruit byproduct. The pulp of the passion fruit is one of the main products from the fruit, and the peels and the seeds are the main byproduct resulting from its processing. The aim of this study was to develop a yogurt with passion fruit pulp and flour produced from byproduct of industrialization of fruit. In total, seven samples were evaluated yogurt among which five had flour of passion fruit in their composition. It was perfomed by physico-chemical analyses, microbiological, pesticide residue, acceptability test and purchase intent, quantitative descriptive analysis (QDA), the estimated of useful life and development of product labels. All yogurts with flour showed high levels of dietary fiber. No pesticide residues were detected in byproducts of passion fruit samples. It was observed that the incorporation of passion fruit flour showed positive effects on the mineral content and viscosity but negative aspects such as color and pH. A greater acceptance was observed for yoghurt without flour. However, the yogurt with low concentration of this ingredient (yogurt 2%) also showed satisfactory acceptance and relevant purchase intent. The ADQ showed that the addition of the pulp and passion fruit flour influenced the sensory profile of the samples. The treatments with 2% and 4% flour presented the highest scores in the most desirable attributes for a passion fruit yogurt enriched with fiber. The useful life of the product was estimated at 21 days, and during storage, it was observed increase the rate of syneresis, fungal and yeast growth, decreasing of the pH and the number of viable lactic acid bacteria in samples. Taking into account the data obtained, the yogurt with the addition of 2% of flour of passion fruit was more viable than the others

No presente trabalho é feito um estudo sistemático do efeito do campo cristalino nas propriedades ópticas do íon Er3+. Para tal propósito utilizamos três diferentes sistemas cristalinos dopados com Er3+: Ortovanadato de cálcio [Ca3(VO4)2], Niobato de lítio [LiNb03] e Titanato de bismuto [Bi12TiO20]. Os cristais foram crescidos no formato de fibras, pela técnica LHPG (Laser Heated Pedestal Growth). O uso deste método de crescimento permitiu não apenas o estudo do efeito do campo cristalino da matriz no Er3+ como também, a influência de diferentes condições crescimento. As composições dos cristais foram determinadas através de EDX (Energy Dispersive X Ray), XPS (X Ray Photoelectron Spectroscopy) e microscopia Auger. As amostras também foram investigadas através de absorção óptica e emissão, incluindo a determinação de seus índices de refração, gap óptico, identificação e análise de várias transições, medidas de emissão dependentes do tempo e da temperatura. A estrutura de todos os cristais foram investigadas pelas técnicas de difração de raios X e espalhamento Raman. Baseados nos resultados experimentais foi possível inferir sobre as regras impostas pelas condições de crescimento nas propriedades finais das fibras cristalinas de Ca3(VO4)2, LilNbO3 e Bi12Ti020 dopados com Er3+. Especificamente relacionado com as fibras cristalinas de Ca3(VO4)2 e LiNBbO3 dopadas com Er3+, a inserção de diferentes pressões de oxigênio molecular, durante o crescimento, induz mudanças significativas na sua estrutura cristalina. A inserção de íons Er3+ na matiz Bi12Ti020 produz uma luminescência fraca, quando comparada a do Ca3(VO4)2 e LiNbO3, porém esta luminescência apresenta um aumento considerável quando as amostras são co-dopada com íons Ga3+ / In this work we performed a systematic study of the crystal field effect on the optical properties of the Er3+ ion. For such a purpose we used three different crystalline Er3+ doped systems: calcium orthovanadate [Ca3(VO4)2, lithium niobate [LiNbO3] and bismuth titanate [Bi12TiO20]. The crystals were grown in the shape of fibers by the Laser Heated Pedestal Growth (LHPG) technique. By using this growth technique it was possible to explore not only the effects of different crystal fields on the Er3+ ion but also, the influence of different growth conditions. The composition of each fiber was determined from EDX (Energy, Dispersive X Ray , analysis), XPS (X Ray Photoelectron Spectroscopy) and Auger microprobe. The fibers were also optically investigated through optical absorption and emission and included the determination of their index of refraction, optical band gap, the identification and analysis of several different transitions, temperature and time-dependent measurements, etc. The structure of all crystals were investigated by X ray diffraction and Raman scattering techniques. Based on these experimental results it was possible to infer the role played by the growth technique and conditions on the final properties of these Er3+ -doped Ca3(VO4)2, LiNbO3 and Bi12Ti020 crystalline fibers. Specifically related to the Er3+ -doped Ca3(VO4)2 and LiNbO3 fibers, different pressures of molecular oxygen, during the groNvt.h., induces significant changes on their atomic (and electronic) structure. The insertion of Er3+ ions in the Bi12Ti020 matrix produces a small photoluminescence intensity, when compared with Ca3(VO4)2 and LINbO3, which is considerably increased by co-doping with Ga3+ ions

O novo paradigma de se preservar o meio ambiente e de se utilizar produtos naturais vem contribuindo para um maior interesse na utilização de materiais derivados da biomassa. Neste sentido, os compósitos poliméricos com fibras vegetais surgem como uma boa alternativa no campo dos materiais para aplicações de engenharia. Os principais objetivos deste trabalho foram o processamento e a caracterização do compósito formado por uma resina poliuretano derivada do óleo de mamona e fibras de sisal e coco. O processamento foi realizado utilizando-se a técnica de moldagem por compressão. As fibras foram utilizadas em diferentes formas como fibras curtas, fibras longas, tecido e fios contínuos. A caracterização foi realizada através dos seguintes ensaios: tração, flexão, impacto, tenacidade à fratura, absorção d’água e DMTA. Foi também avaliado o efeito do tratamento com hidróxido de sódio (10%), nas fibras de sisal e coco, nas análises realizadas. O resultados mostraram que o desempenho dos compósitos com fibras de coco foi inferior aos compósitos com fibras de sisal, e mesmo ao poliuretano. Nos ensaios de tração e flexão, as fibras longas de sisal apresentaram o melhor efeito de reforçamento, seguido dos fios contínuos, fibras curtas e tecido. Nos ensaios de impacto e tenacidade à fratura, o melhor desempenho foi dos compósitos com tecido de sisal. O efeito do tratamento alcalino variou em função do tipo de ensaio e da geometria do reforço. Nos ensaios de tração e flexão, o seu efeito foi positivo para os compósitos com fibras longas e curtas, e negativo para os compósitos com tecido e fios, devido à deterioração da estrutura dos fios. Nos ensaios de tenacidade e impacto foi prejudicial, pois ao melhorar a aderência na interface, reduziu os principais mecanismos de absorção de energia, que são, a extração de fibras e o descolamento na interface. Com relação às medidas de absorção d’água, foi observado aumento no nível de absorção dos compósitos com o aumento da fração volumétrica de fibras. O máximo percentual de absorção foi de 17%, para os compósitos com fibras curtas de coco não tratadas. Este percentual diminuiu com o tratamento alcalino das fibras. Na análise térmica dinâmico mecânica, de uma forma geral, os compósitos mostraram acréscimo do módulo de armazenamento e decréscimo do amortecimento e da temperatura de transição vítrea, Tg, em relação ao poliuretano. Este comportamento foi proporcional ao aumento da fração volumétrica de fibras. / The new paradigm in preserving the environment and the use of natural products has contributed to increase the interest in the development and use of derived biomass materials. In this sense, the polymeric composites with natural fibers appear to be a good alternative for engineering applications. The main targets of this work were the processing and characterization of composites obtained by a polyurethane resin derived from castor oil and sisal and coir fibers. The compression moulding technique was used to process the composite. The fibers were employed in different forms such as: short fibers, long fibers, biaxial weave and continuos yarns. Tension, bend, impact, fracture toughness, water absorption and DMTA tests were used to characterize the composites. The sodium hidroxide (10%) treatment effect on the sisal and coir fibers was also evaluated. The results showed, in general, that the coir fibers composites performance were inferior to the sisal fibers composites, and even to the polyurethane matrix. Under tension and bending conditions, the long sisal fibers presented the best reinforcement effect, followed by the continuous yarns, short fibers, and the biaxial weave. Under impact and fracture toughness tests, the best performance was enhanced by sisal weave composites. The alkaline treatment effect varied in accordance with test type and reinforcement geometry. In tension and bending tests, its effect was positive for composites with short and long fibers and negative for composites with weave and yarns. This late was due to deterioration of the yarn structure. In the impact and toughness tests, the alkaline treatment effect was harmful, because when adherence is improved at the interface, the main energy absorption mechanisms are reduced, that mean, the fibers are pulled out and interface is debonded. Water absorption measurements showed an increase in the absorption level for the composites with higher volumetric fraction of fibers. The maximum water absorption was 17% for composites with non-treated coir short fibers. This percentage decreased for composites with treated fibers. In the dynamic mechanical thermal analysis (DMTA) the composites showed an increased storage modulus and a decreased glass transition temperature, Tg, when compared to polyurethane matrix. This behaviour was proportional to the increase of the fibers volumetric fraction.