Thesis (PhD)--Stellenbosch University, 2004. / Bibliography / ENGLISH ABSTRACT: Heart failure due to cardiomyopathy or cardiac conduction disease is a major cause of mortality and morbidity in both developed and developing countries. Although defined as separate clinical entities, inherited forms of cardiomyopathies and cardiac conduction disorders have been identified that present with overlapping clinical features and/or have common molecular aetiologies. The objective of the present study was to identify the molecular cause of progressive familial heart block type II (PFHBII), an inherited cardiac conduction disorder that segregates in a South African Caucasian Afrikaner family (Brink and Torrington, 1977). The availability of family data tracing the segregation of PFHBII meant that linkage analysis could be employed to identify the chromosomal location of the disease-causative gene. Human Genome Project (HGP) databases have provided additional resources to facilitate the identification of positional candidate genes. Clinical examinations were performed on individuals of the PFHBII-affected family, and, where available, clinical records of subjects examined in a previous study by Brink and Torrington (1977) were re-assessed. Retrospective data suggested redefining the classification of PFHBII. Subsequently, linkage analysis was used to test described dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM) and cardiac conduction-causative loci on chromosomes 1, 2, 3, 6, 7, 9, 11, 14, 15 and 19 for their involvement in the development of PFHBII. Once a locus was mapped, bioinformatics tools were applied to identify and prioritise positional candidate genes for mutation screening. The retrospective and prospective clinical study redefined PFHBII as a cardiac conduction and DCM-associated disorder and simultaneously allowed more family members to be traced. Fortuitously, candidate loci linkage analysis mapped the PFHBII locus to chromosome 1q32, to a region that overlapped a previously described DCM-associated disorder (CMD1D), by the generation of a maximum pairwise lod score of 3.13 at D1S3753 (theta [θ]=0.0) and a maximum multipoint lod score of 3.7 between D1S3753 and D1S414. However, genetic fine mapping and haplotype analysis placed the PFHBII-causative locus distal to the CMD1D locus, within a 3.9 centimorgan (cM) interval on chromosome 1q32.2-q32.3, telomeric of D1S70 and centromeric of D1S505. Bioinformatics analyses prioritised seven candidate genes for mutation analysis, namely, a gene encoding a potassium channel (KCNH1), an extracellular matrix protein (LAMB3), a protein phosphatase (PPP2R5A), an adapter protein that interacts with a cytoskeletal protein (T3JAM), a putative acyltransferase (KIAA0205) and two genes encoding proteins possibly involved in energy homeostasis (RAMP and VWS59). The PFHBII-causative mutation was not identified, although single sequence variations were identified in four of the seven candidate genes that were screened. Although the molecular aetiology was not established, the present study defined the underlying involvement of DCM in the pathogenesis of PFHBII. The new clinical classification of PFHBII has been published (Fernandez et al., 2004) and should lead to tracing more affected individuals in South Africa or elsewhere. The identification of a novel disease-causative locus may point toward the future identification of a new DCM-associated aetiology, which, in turn, might provide insights towards understanding the associated molecular pathophysiologies of heart failure. / AFRIKAANSE OPSOMMING: Hartversaking as gevolg van kardiomiopatie of kardiale geleidingsiekte is ‘n hoof-oorsaak van mortaliteit and morbiditeit in beide ontwikkelde en ontwikkelende lande. Alhoewel gedefinieer as verskillende kliniese entiteite is oorerflike vorms van kardiomiopatie en kardiale geleidingsstoornisse geïdentifiseer met oorvleuelende kliniese eienskappe en/of molukulêre oorsake. Die doelwit van hierdie studie was om die molukulêre oorsaak van progressiewe familiële hartblok tipe II (PFHBII), ‘n oorerflike kardiale geleidingsstoornis, wat in ‘n Suid-Afrikaanse Kaukasiër familie segregeer (Brink en Torrington, 1977), te identifiseer. Die beskikbaarheid van familie data, beteken dat koppelingsanalise gebruik kan word om die chromosomale posisie van die siekte-veroorsakende geen te identifiseer. Menslike Genoom Projek (MGP) databanke het addisionele hulpbronne beskikbaar gestel om die identifikasie van posisionele kandidaat gene te vergemaklik. Kliniese ondersoeke is uitgevoer op PFHBII-geaffekteerde familielede, en waar beskikbaar is kliniese rekords van persone, wat in ‘n vorige studie deur Brink en Torrington (1977) geassesseer was, herontleed. Retrospektiewe data-analise het die kliniese herdefinisie van PFHBII voorgestel. Daarna is koppelingsanalise gebruik om dilateerde kardiomiopatie (DKM), hipertrofiese kardiomiopatie (HKM) en kardiale geleidingssiekte-veroorsakende loki op chromosoom 1, 2, 3, 6, 7, 9, 11, 14, 15 en 19 te ondersoek vir hul moontlike bydrae tot die ontwikkeling van PFHBII. Toe die lokus gekarteer was, is bioinformatiese ondersoeke gebruik om posisionele kandidaat gene te identifiseer en prioritiseer vir mutasie analise. Die retrospektiewe en prospektiewe kliniese ondersoek het PFHBII herdefinieer as ‘n geleidingsstoornis en DKM-verbonde siekte, en terselfde tyd het dit gelei tot die opsporing van nog familielede. Toevallig het kandidaat loki-analise die PFHBII lokus op chromosoom 1q32 gekarteer, na ‘n gebied wat met ‘n voorheen-beskyfde DKM-verbonde stoornis (CMD1D) oorvleuel, met die opwekking van ‘n makisimum paargewyse lod-getal van 3.13 by D1S3753 (theta [θ] = 0.0) en ‘n maksimum multipunt lod-getal van 3.7 tussen D1S3753 en D1S414. Genetiese fynkartering en haplotipe-analise het die PFHBII-veroorsakende lokus afwaards van die CMD1D lokus geplaas, in ‘n 3.9 centimorgan (cM) gebied op chromosoom 1q32.2-q32.3, telomeries van D1S70 en sentromeries van D1S505. Bioinformatiese analise het daarnatoe gelei dat sewe kandidaat gene vir mutasie analise geprioritiseerd is, naamlik, gene wat onderskeidelik ‘n kalium kanaal (KCNH1), ‘n ekstrasellulêre matriksproteïen (LAMB3), ‘n proteïen fosfatase (PPP2R5A), ‘n aansluiter proteïen wat met ‘n sitoskilet proteïen bind (T3JAM), ‘n asieltansferase (KIAA0205) en twee gene moontlik betrokke in energie homeostase (RAMP en VWS59) enkodeer. Die PFHBII-veroorsakende geen is nie geïdentifiseer nie, alhoewel enkele volgorde-wisselings geïdentifiseer is in vier van die sewe geanaliseerde kandidaat gene. Alhowel die molekulêre oorsaak van die siekte nie vasgestel is nie, het die huidige studie die onderliggende betrokkenheid van DKM in die pathogenese van PFHBII gedefinieer. Die nuwe kliniese klassifikasie van PFHBII is gepubiliseer (Fernandez et al., 2004) en sal lei tot die identifisering van nog geaffekteerde persone in Suid Afrika of in ander lande. Die identifikasie van ‘n nuwe siekte-verbonde lokus mag lei tot die toekomstige identifikasie van ‘n nuwe DKM-verbonde genetiese oorsaak wat, opsig self, dalk insig kan gee in die molekulêre patofisiologie van hartversaking.

Ce travail s'inscrit dans le cadre du développement des piles à combustible à céramique conductrice protonique (PCFC) opérant dans le domaine de température 400 – 600 °C et concerne l'optimisation des composants de la cellule élémentaire. L'optimisation du matériau électrolytique consiste à rechercher le meilleur compromis entre stabilité chimique et conductivité élevée. Le matériau BaCe0.9Y0.1O2.95, synthétisé par la voie flash combustion, présente la conductivité protonique la plus élevée (10-2 S.cm-1 à 600 °C) mais réagit fortement avec le CO2. La substitution partielle du cérium par le zirconium (BCZY) et le niobium (BCYN30) a conduit à une amélioration significative de la stabilité chimique tout en conservant une conductivité de l'ordre de 5 × 10-3 S.cm-1 à 600 °C. En ce qui concerne les électrodes, l'enjeu est de développer des matériaux présentant une conductivité électronique élevée, une porosité suffisamment importante et une bonne tenue mécanique. L'approche a consisté en la mise au point de stratégies d'élaboration (synthèse en une étape, utilisation de porogène) permettant le contrôle de la microstructure des matériaux anodiques afin de minimiser les résistances spécifiques surfaciques (ASR). Comme dans le cas des SOFC, les matériaux cathodiques sont conducteurs mixtes ionique-électronique (MIEC). Le développement de cathodes composites MIEC-électrolyte a permis de réduire significativement les ASR. Les tests en pile de cellules élémentaires PCFC ont révélé que les performances dépendaient essentiellement de la nature et de l'épaisseur du matériau électrolytique et de la mise en œuvre de matériaux d'électrode de morphologie contrôlée et architecturée. L'optimisation des assemblages a permis d'accroître sensiblement les performances (156 mW.cm-2 à 600 °C). / Materials components for a Proton Conducting Fuel Cell (PCFC) operating in the 400 – 600 °C temperature range have been optimised. Electrolyte material optimisation involved finding the best compromise between chemical stability and conductivity. BaCe0.9Y0.1O2.95, synthesised by flash combustion, exhibits the highest protonic conductivity (10-2 S.cm-1 at 600 °C) but reacts strongly with CO2. Partial substitution of cerium by zirconium (BCZY) and niobium (BCYN30) led to a significant improvement of the chemical stability without drastic effect on the conductivity (5 × 10-3 S.cm-1 at 600 °C). The aim for the electrodes is to develop materials which exhibit high electronic conductivity, sufficient degree of porosity and good mechanical properties. The approach comprised the development of elaboration strategies (one-step synthesis, use of porogen) that allow the control of microstructure in order to minimize area specific resistances (ASR) at the anode. As in the case of SOFCs, cathodic materials are mixed ionic-electronic conductors (MIEC). Development of composite cathodes MIEC-electrolyte led to a significant reduction of ASR. PCFC single cell tests showed that performance was mostly dependent on electrolyte thickness and composition, and on the characteristics of nanostructured electrodes with controlled architecture and porosity. Optimisation of assemblies led to fuel cells performances of 156 mW.cm-2 at 600 °C.

A neuropatia hansênica e a neuropatia hereditária com suscetibilidade à pressão (Hereditary Neuropathy with liability to Pressure Palsies - HNPP) são mononeuropatias múltiplas em que os estudos da condução nervosa (ECN) mostram geralmente alentecimento focal em topografias muito semelhantes. Na ausência de uma história familiar de HNPP e das manifestações na pele típicas da hanseníase, o diagnóstico diferencial entre elas pode ser muito difícil. Procurando identificar características que ajudassem a distinguir essas doenças, revisamos e catalogamos os dados da história clínica e dos ECN de 39 pacientes com HNPP e 78 pacientes com neuropatia hansênica. A manifestação inicial mais frequente na hanseníase foi o déficit sensitivo (43 pacientes-55.1%) e na HNPP foi a fraqueza muscular localizada indolor (24 pacientes-61%). Fraqueza muscular foi significativamente superior na HNPP e déficit sensitivo foi significativamente superior na hanseníase (p<0.001). A evolução clínica foi estável ou progressiva até o tratamento em todos os pacientes com hanseníase e na HNPP dez pacientes (25.6%) tiveram um curso progressivo e 29 (74.4%) uma evolução com flutuações. O padrão predominante ao exame neurológico foi a mononeuropatia múltipla: 66 pacientes (84.6%) na hanseníase e 26 pacientes (66.7%) na HNPP. Espessamento neural foi mais frequente na hanseníase (p=0,001) e déficit sensitivo intradérmico foi observado somente na hanseníase (p<0,001). Episódio prévio ou atual de paralisia aguda de nervo foi referido somente na HNPP (p<0,001). O padrão dos ECN prevalente foi a neuropatia sensitivo-motora assimétrica com alentecimento focal da condução (NSMAAF): 44 pacientes (56.4%) na hanseníase e 31 pacientes (94.0%) na HNPP. Os parâmetros clínicos mais úteis em distinguir as duas doenças foram: a perda sensitiva intradérmica com comprometimento precoce das fibras finas e ocorrência de reação hansênica na hanseníase; o envolvimento motor inicial predominante, episódios de paralisia aguda de nervo e a evolução com flutuações na HNPP. Se o paciente a ser avaliado apresentar mononeuropatia múltipla com alentecimentos focais da velocidade de condução, os seguintes achados neurofisiológicos sugerem hanseníase: a não detecção de potenciais sensitivos ou motores, a redução da amplitude dos potenciais de ação sensitivos dos nervos sural, fibular superficial e radial superficial (< 8,8 ?V), a redução da amplitude do potencial de ação muscular composto dos nervos ulnar e tibial posterior, a redução da velocidade de condução do potencial de ação muscular composto do nervo ulnar motor no segmento do antebraço (< 43 m/s) e a presença de dispersão temporal frequente; enquanto os seguintes achados sugerem HNPP: aumento desproporcional da latência distal do nervo mediano motor e a presença de bloqueio de condução. / The Hansen\'s disease neuropathy (HDN) and the Hereditary Neuropathy with liability to Pressure Palsies (HNPP) are multiple mononeuropathies whose nerve conduction studies (NCS) usually show focal slowing at very similar topographies. In the absence of a family history of HNPP and the typical skin manifestations of HD, the differential diagnosis between them may be very difficult. In order to identify characteristics that may distinguish these diseases, we reviewed the data of 39 patients with HNPP and of 78 patients with HDN. The most frequent presenting sign was a sensory deficit in 43 patients (55.1%) in the HDN and a localized painless muscular weakness in 24 patients (61%) in the HNPP. Muscle weakness was significantly higher in HNPP and sensory deficit was significantly higher in leprosy (p<0.001). The disease was stable or progressive until treatment in all patients with HDN and among HNPP ten patients (25.6%) had a progressive course and 29 (74.4%) an intermittent evolution. Neural thickening was more frequent in leprosy (p=0.001) and intradermal sensory deficit was observed only in leprosy (p<0.001). Previous or current episode of acute nerve palsy was reported only in HNPP (p<0.001). The predominant pattern on neurological examination was the multiple mononeuropathy: 66 patients (84.6%) in the HDN and 26 patients (66.7%) in the HNPP. The most prevalent pattern of NCS was an asymmetric sensorimotor neuropathy with focal slowing (ASMNFS): 44 patients (56.4%) in HDN and 31 patients (94.0%) in HNPP. The most helpful clinical parameters in distinguishing these diseases were the presence of leprosy reaction and the intradermal sensory loss with predominant early involvement of small nerve fibers in HDN; the initial predominant motor involvement, episodes of acute nerve palsies and the intermittent evolution in HNPP. If the patient evaluation show a pattern of multiple mononeuropathy with focal slowing, the following neurophysiological findings suggest HDN: no detection of sensory or motor potentials, amplitude reduction of the sural, superficial fibular and superficial radial (<8.8 ?V) nerves, amplitude reduction of the motor ulnar and posterior tibial nerves, reduction of the conduction velocity of the motor ulnar nerve at the forearm segment (<43 m/s) and the presence of frequent temporal dispersion; while the following findings suggest HNPP: a disproportionate increase in the motor distal latency of the median nerve and the presence of conduction block.

La polyaniline est un polymère conducteur intrinsèque aux potentialités indéniables dans le domaine de la micro-électronique. Elle allie la légèreté, le faible coût et la modularité des polymères avec les propriétés de conduction électrique des métaux. La mise à profit de ce mélange de propriétés à l’échelle industrielle nécessite une maitrise des procédés de mise en œuvre de la polyaniline, notamment sous forme de film polymère, domaine où il y a encore un manque de maitrise. Pour y remédier, il faudrait tout d’abord comprendre l’influence de chaque paramètre de mise en œuvre sur les propriétés de conduction du film de polyaniline. Pour cela, nous avons choisi une polyaniline plast-dopée commerciale à l’état de dispersion et avons fait une étude paramétrique sur l’effet du type de solvant utilisé pour la dispersion ainsi que celui de la température d’évaporation de celui-ci lors du dépôt du film. Deux types d’études ont été menés : la première porte sur les propriétés rhéologiques et diélectriques des dispersions de polyaniline et la seconde sur les propriétés structurales et de conduction des films. A travers la première étude, nous avons pu montré que lors du chauffage des dispersions de polyaniline, celles-ci subissaient une transition structurale liquide-liquide du second ordre dont les paramètres varient avec le type du solvant utilisé. A travers la seconde étude, nous avons aussi mis en évidence que les films déposés dans les domaines avoisinant la température transition de phase dans les mélanges liquides sont les moins conducteurs et les moins cristallisés. Selon le type de solvant choisi, deux mécanismes de conduction ont été trouvés : les sauts à portées variables tridimensionnel (VRH 3D), pour le cas de la série de films issus de la dispersion dans l’acide dichloroacétique et déplacement par effet tunnel induit par les fluctuations thermiques (FIT) pour la série de films issus de la dispersion dans le mélange acide dichloroacétique / acide formique. Il en ressort finalement que pour obtenir un film de polyaniline plast-dopée ayant la conductivité la plus élevée, il faut appliquer les conditions expérimentales qui permettent d’obtenir un degré de cristallinité élevé (298 K pour PANI/DCAA). / The purpose of this study is to perform polyaniline films with the highest conductivity. The effect of the solvent type and the casting temperature on the electrical properties of plastdoped polyaniline dispersions and films were investigated. For this purpose, rheological and dielectric investigations have been undertaken for dispersions of plast-doped polyaniline in two different solvents (dichloroacetic acid and formic acid / dichloroacetic acid mixture). Changes appearing above a certain temperature, 318K for PANI/DCAA and 313K for PANI/DCAA-FA, for both rheological dielectric and rheological parameters revealed the existence of a second order liquid-liquid structural transition occurring in the polyaniline organic dispersions. We also investigated the effect of the selected processing parameters on the film properties. We found that the DC conductivity mechanism is governed by Mott’s three-dimensional variable range hopping (3D VRH) model for PANI/DCAA films and by a fluctuation induced tunnelling model (FIT) for PANI/DCAA-FA films. Besides, the films cast at temperatures around the second order liquid-liquid structural transition temperature of polyaniline dispersions lead to the lowest conductivity and crystallinity, regardless of the solvent type used. A qualitative correlation was also found between the conductivity and the crystallinity of the polyaniline films. So, in order to obtain films with the highest electric conductivities, we have to apply experimental conditions leading to the highest crystallinity (298 K for PANI/DCAA).

Descreve-se neste trabalho um estudo experimental da Emissão Eletrociclotrônica (EEC) no tokamak TCABR. Um radiômetro de EEC foi instalado, calibrado e utilizado para o estudo do plasma em descargas térmicas. O radiômetro é do tipo heteródino de varredura operando na faixa de 50-85 GHz, no modo extraordinário e na segunda harmônica. Determinou-se a temperatura de ruído do radiômetro e também sua estabilidade em amplitude e freqüência. Foi medida a largura de banda em freqüência do radiômetro (resolução espacial horizontal). A antena utilizada é do tipo gaussiana sendo que o raio da cintura do feixe gaussiano e a posição do foco foram experimentalmente determinados (W0 ~ 1 cm e d ~ 37 cm, respectivamente). A posição da cintura da antena foi posicionada próxima do centro geométrico do vaso. Foi feita a calibração absoluta do equipamento considerando-se os efeitos das janelas de diagnóstico (reflexão e absorção). O sistema pode operar em modo varredura, para a obtenção de perfis radiais de Te ou modo freqüência única onde se tem alta resolução temporal. As medidas da radiação EC foram feitas, na sua maioria, em descargas com densidade eletrônica média entre 1.10+19 m-3 e 1,5.1019 m-3 de forma a se ter acessibilidade da radiação EC e também minimizar-se a presença de elétrons fugitivos. Para ne > 1,5.1019 m-3 (com B0 = 1,14 T) verifica-se o corte parcial da radiação EC. Nesta condição, o corte na EEC foi utilizado na determinação do perfil radial da densidade eletrônica e aplicado em três diferentes situações: descargas com injeção adicional de gás, com a aplicação do eletrodo de polarização e em descargas com injeção de ondas de radiofreqüência na região das ondas de Alfvén para o TCABR. Usando um perfil parabólico típico para a densidade eletrônica, observou-se que, para descargas com injeção adicional de gás ou em descargas com a aplicação de ondas de radiofreqüência tem-se 0,85 < alfa < 1, e para descargas com aplicação do eletrodo de polarização obteve-se alfa ~ 0,6. Foram feitas observações simultâneas da temperatura eletrônica, a partir do sinal da EEC, e das oscilações de Mirnov (freqüência ~ 11,7 kHz) em descargas térmicas com q(r=0) > 1. Os resultados indicam a presença de um modo de ruptura dominante em rs ~ 9,5 cm com a largura da ilha magnética de W ~ 2,0-2,5 cm. Estes resultados experimentais obtidos estão em acordo com os resultados indicados por teorias de transporte na região das ilhas magnéticas. Observou-se também que a localização da ilha magnética coincide com uma região onde o perfil radial da temperatura de plasma é aproximadamente plano. Num outro cenário, com q(r=0) < 1, observaram-se oscilações dente de serra com período de ~ 0,44 ms, tempo de queda de ~ 0,12 ms, e raio de inversão em r ~ 4 cm. Neste tipo de descargas observou-se que, no perfil radial da amplitude das oscilações da Te, |DeltaTe|, devido à propagação dos pulsos dente de serra, apresentavam posições de mínimos e que estes coincidiam com as posições onde ocorrem patamares no perfil radial da temperatura eletrônica. Partindo destes resultados, juntamente com o perfil de q(r), dão-nos os modos racionais (m/n), posições (r) e larguras(W) para as ilhas magnéticas, presentes nestas descargas, a saber: m/n = 4/3 (r ~ 9 cm, W4/3 ~ 0,9 cm), m/n = 3/2 (r ~ 11,8 cm, W3/2 ~ 0,9 cm) e m/n = 2/1 (r ~ 13,7 cm, W2/1 ~ 1,4 cm). Este novo método, aqui proposto, permite a determinação direta da posição e da largura das ilhas magnéticas, em descargas onde a instabilidade dente de serra encontra-se presente.¶ / In this work, an experimental study of the Electron Cyclotron Emission (ECE) in the TCABR Tokamak, is described. An ECE sweeping heterodyne radiometer, operating in the 50-85 GHz frequency range, was installed, calibrated and used to detect ECE radiation in the second harmonic extraordinary mode from thermal plasma discharges. The noise temperature, amplitude and frequency stability of the radiometer were determined. The frequency bandwidth (horizontal space resolution) was measured. A Gaussian Antenna is used and the gaussian beam waist radius (W0 ~ 1 cm) and the focus position (d ~ 37 cm) were experimentally determined. The focus of the antenna was positioned close to the center of the vacuum vessel. The absolute calibration of the equipment was done and the effect of the diagnostic window was considered (reflections and absorptions). The system can operate in sweeping mode, in order to obtain the radial electron temperature profiles, and also in the single frequency mode to obtain temporal electron temperature profiles with high time resolution. Due to the TCABR accessibility conditions and also to avoid runaway electrons, most of the ECE measurements were obtained in discharges with line electron density between 1.0x10+19 m-3 and 1.5x1019 m-3. For ne > 1.5x1019 m-3 (with B0 = 1.14 T) the cutoff in the ECE radiation was observed. The ECE cutoff was used to determine the radial profile of the electron density and applied to three different situations: discharges with additional gas puffing, with the application of a biasing electrode and in discharges with radio-frequency wave injection. Using a parabolic profile it was observed that, 0.85 < alfa < 1.0 for discharges with additional gas injection or with RF injection, and alfa ~ 0.6 for the electrode biasing experiments. The electron temperature profiles and Mirnov oscillations (f ~ 11.7 kHz) were simultaneously measured in discharges with q (r=0) > 1. The position and the width of the magnetic island were therefore calculated. The results indicate the presence of a dominant tearing mode in rs ~ 9.5 cm and the magnetic island width W ~ 2.0-2.5 cm. These experimental results are in agreement with the theoretical results foreseen by models of heat transport in the presence of magnetic islands. It was also observed that, the position of the magnetic island coincided with the region where the temperature radial profile is approximately flat. In another plasma scenario, with q(r=0) < 1, sawteeth oscillations with a period ~ 0.44 ms, crash time ~ 0.12 ms, inversion radius r ~ 4 cm, were measured. Peculiarities in the Te radial profile associated with the amplitude of Te oscillations, |DeltaTe|, due to the sawtooth instability, were observed. It was verified that the minimum values of the |DeltaTe| profile coincided with the region where the temperature radial profile was approximately flat. These results together with the q(r) profile yielded the following mode numbers (m/n), positions (r) and widths (W) of the magnetic islands: m/n = 4/3 (r ~ 9 cm, W4/3 ~ 0.9 cm), m/n = 3/2 (r ~ 11.8 cm, W3/2 ~ 0.9 cm) and m/n = 2/1 (r ~ 13.7 cm, W2/1; ~ 1.4 cm). A novel method to determine the position and width of the magnetic islands, in discharges with the presence of sawtooth instability, is presented here.

O problema da condução de calor, envolvendo mudança de fase, foi resolvido para o caso de uma cavidade limitada por duas superfícies cilíndricas indefinidamente longas. As condições de contorno impostas consistem em manter a temperatura da superfície interna fixa e abaixo da temperatura de fusão do material que preenche a cavidade, enquanto que a temperatura da superfície externa é mantida fixa e acima da temperatura de fusão. Como condição inicial se fixou a temperatura de todo o material que preenche a cavidade no valor da temperatura da superfície externa. A solução obtida consiste em duas soluções da equação de condução de calor, uma escrita para o material solidificado e outra escrita para o material em estado líquido. As duas soluções são formalmente escritas em termos da posição da frente de mudança de fase, que é representada por uma superfície cilíndrica com raio em expansão dentro da cavidade. A posição dessa superfície é, a princípio, desconhecida e é calculada impondo o balanço de energia através da frente da mudança de fase. O balanço de energia é expresso por uma equação diferencial de primeira ordem, cuja solução numérica fornece a posição da frente como função do tempo. A substituição da posição da frente de mudança de fase em um instante particular, nas soluções da equação de condução de calor, fornece a temperatura nas duas fases naquele instante. A solução obtida é ilustrada através de exemplos numéricos. / The heat conduction problem, in the presence of a change of state, was solved for the case of an indefinitely long cylindrical layer cavity. As boundary conditions it is imposed that the internal surface of the cavity is maintained below the fusion temperature of the infilling substance and the external surface is kept above it. The solution, obtained in non-dimensional variables, consists in two closed form heat conduction equation solutions for the solidified and liquid regions, which formally depend of the, at first, unknown position of the phase change front. The energy balance through the phase change front furnishes the equation for time dependence of the front position, which is numerically solved. Substitution of the front position for a particular instant in the heat conduction equation solutions gives the temperature distribution inside the cavity at that moment. The solution is illustrated with numerical examples.

Os contêineres metálicos foram desenvolvidos para a utilização no setor de logística e transporte, mas por sua escala adaptável à das edificações e pela mobilidade e praticidade de instalação, tiveram sua utilização apropriada também pelo setor da construção civil. Essas instalações possuem diversas qualidades ambientalmente amigáveis, mas seu aspecto térmico é extremamente insuficiente: sem isolamento térmico, demandam alta carga térmica de refrigeração e aquecimento, no verão e inverno, respectivamente e, consequentemente, um alto consumo energético. Tal característica foi crucial para que se determinassem como objetivos da presente pesquisa investigar o comportamento térmico dessas construções metálicas, avaliar seus parâmetros de desempenho, conforto e estresse térmicos, por meio de uma ampla coleta de dados experimentais. O experimento com duração de um ano - contou com três tipologias de contêiner em escala real, sendo o primeiro em aço Tipo X sem isolamento térmico, o segundo com um isolamento térmico para o fenômeno da condução e o terceiro com isolamento térmico para o fenômeno da radiação. Os diferentes tipos de tratamentos térmicos proporcionaram melhorias à envoltória dos contêineres, chegando a uma diferença nas temperaturas internas de até 9 °C. Constatou-se a extrema necessidade de adequação do tipo de isolamento térmico dos contêineres ao uso a que tais instalações se destinam escritório ou alojamento, no caso dos canteiros de obras para que as características da envoltória minimizem de fato a demanda ou mesmo atinjam a eliminação da necessidade de condicionamento artificial. / Metal containers were developed to logistics and transportation sector, but as a result of their suitable scale to human occupation, and their mobility and installation convenience, their use was adopted by the construction sector. These installations have many environmentally friendly characteristics, but their thermal performance is extremely unsuitable for habitation: without thermal insulation, the containers have high cooling and heating thermal load, in summer and winter, respectively, and consequently, to achieve thermal comfort, a substantial amount of energy is consumed. This feature was important to determine that the researchs objectives were to investigate metallic constructions thermal performance, calculate their thermal performance parameters, thermal comfort and thermal stress through a wide collection of experimental data. The experiment with duration of one year was conducted in three real scale containers: all of them made of steel (called steel Type X): the first one had no thermal insulation, the second one had insulation for thermal conduction, and the third had a thermal barrier for radiation. This different types of thermal treatment provided improvement to the containers envelopes, achieving a difference in internal temperatures about 9 °C. The findings reveal that thermal insulation needs to correctly respond to the containers intended use office or accommodation, in the case of construction sites so that the envelopes characteristics can have an impact on minimizing energy demand or even eliminate the containers need for artificial heating and cooling.

A têmpera dos aços envolve a austenitização de uma peça seguida por um resfriamento rápido para promover a formação de microestrutura martensítica. É necessário avaliar os meios de têmpera para manter o processo de têmpera sob controle. Os parâmetros mais importantes no processo de resfriamento são o coeficiente de transferência de calor e/ou o fluxo de calor entre o meio de têmpera e a peça a ser resfriada. Um dos métodos de se avaliar os meios de têmpera (meios de resfriamento) e saber o que está acontecendo dentro da peça durante o resfriamento do ponto de vista térmico é o problema inverso de condução de calor. O problema inverso de condução de calor consiste na determinação de parâmetros como fluxo de calor, taxa de resfriamento e temperatura em qualquer posição através da peça, assim como o coeficiente de transferência de calor. Esses parâmetros são obtidos a partir de medições de temperatura em um ou mais pontos dentro da peça. O escopo deste trabalho foi desenvolver um software baseado no problema inverso condução de calor para avaliar meios de resfriamento para têmpera. A validação deste código foi feita usando água, óleo de soja, óleo mineral e solução aquosa de NaNO3. / Steels quenching involves part austenitization followed by a fast cooling to promote martensitic microstructure formation. It is necessary to evaluate quenchants in order to keep the quenching process under control. The most important cooling process parameters are the heat transfer coefficient and/or the heat flux between the quenchant and the part to be cooled. One of the methods to evaluate quenchants (cooling media) and to know what is happening inside the part during the cooling in the thermal point of view is the inverse heat conduction problem. The inverse heat conduction problem consists in the determination of parameters like heat flux, cooling rate and temperature in any position across the part, as well as the heat transfer coefficient. These parameters are obtained from temperature measurements in one or more points inside the part. The scope of this work was to develop a software based in the inverse heat conduction problem in order to evaluate quenchants for quenching. The validation of this code was made using water, soybean oil, mineral oil and NaNO3 aqueous solution.

Despite advancements in the development of synthetic fibers and materials that provide better insulation, fire ground burn injuries remain a significant issue. The current test methods for fire fighting clothing were investigated to determine their adequacy in evaluating the actual performance of clothing materials. This investigation uncovered several potential problems with the current test methods. A series of new, small scale, tests were used to evaluate the shortcomings of the current test methods and develop possible improvements. A small test apparatus, designed and donated by Ktech Corporation, was used to measure the thermal properties (thermal conductivity and volumetric heat capacity) of a series of fire fighting clothing materials. The thermal properties were estimated for single fabric layers, as well as ensembles, with various levels of moisture added to simulate actual end use conditions. In addition, a skin simulant sensor was used to assess the time to 2nd degree burn for exposures similar to those required in current standards for fire fighting clothing. A one dimensional heat conduction model was developed to predict the time to 2nd degree burn for the skin simulant sensor protected with outer shell materials that may be used as wildland fire fighting clothing, using the thermal property data obtained from earlier tests. An alternative method was developed to calculate the time to 2nd degree burn for ensembles evaluated with the new skin simulant sensor. The predictions for the time to 2nd degree burn obtained from the new skin simulant sensor were compared against results obtained using the sensor specified in the current test methods. The predictions for the skin simulant sensor were consistently shorter than those from the current test sensor. The current test sensor predictions for the time to 2nd degree burn were nominally 40% to 50% higher than the predictions from the skin simulant sensor during the evaluations of outer shell materials.

Submitted by Eunice Novais (enovais@uepg.br) on 2017-09-01T17:51:26Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Luiz Fernando K Unti.pdf: 6181881 bytes, checksum: b0280e86919fc3c265d97d1ffba8200e (MD5) / Made available in DSpace on 2017-09-01T17:51:26Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Luiz Fernando K Unti.pdf: 6181881 bytes, checksum: b0280e86919fc3c265d97d1ffba8200e (MD5) Previous issue date: 2017-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Dentre os materiais mais comuns utilizados para a construção de eletrólitos e eletrodos das células a combustível de óxido sólido (CaCOS) estão os óxidos com estrutura semelhante à perovisquita; estes apresentam características desejáveis para esta aplicação, como boa condutividade elétrica. Diversos são os estudos nesta área atualmente, onde um dos enfoques é o desenvolvimento de materiais com condutividade protônica para melhorar a performance destes condutores. O presente trabalho avaliou a viabilidade do composto Ba5Nb4O15 (BNO) como possível candidato na produção de elementos de CaCOS. Este composto possui uma estrutura de perovisquita hexagonal, e estudos recentes apontam que é largamente utilizado em ressoadores dielétricos e há indícios que este tipo de estrutura pode apresentar condutividade protônica. Nesse trabalho foi avaliada a síntese da fase BNO através de um método alternativo à reação no estado sólido, baseada no método Pechini modificado, usando para isto precursores no formato de óxido. Como há diversas rotas diferentes de processamento para esta fase, comparou-se a sinterabilidade dos pós obtidos nas sínteses através da densificação, após serem conformados e sinterizados em duas temperaturas: 1400 e 1450ºC. Também se estudou a influência da adição de dopantes de menor valência (titânio e zircônio) na estrutura e nas propriedades elétricas da fase pura. Foi possível obter a fase BNO em todas as sínteses, embora após a primeira calcinação houvesse diferentes fases na amostra obtida pelo método Pechini; estas fases secundárias desapareceram após a sinterização. Atingiu-se maior densificação ao submeter os pós sintetizados à moagem, previamente à conformação, onde se atingiu porosidades aparentes menores que 5%. As dopagens promoveram o refino do grão, mas não foram eficientes no aumento da condutividade do composto. Contudo, as amostras sinterizadas em 1450ºC apresentaram maior condutividade em atmosfera úmida (H2O) do que em água pesada (D2O), o que pode ser um indício da existência de condutividade protônica nesta estrutura. / Among the common materials used to produce solid oxide fuel cell’s (SOFC’s) electrolytes and electrodes areoxides with perovskite structures; they show desirable characteristics for this application, like good levels of ionic conduction. Nowadays, there are many different studies on this field, where developing new proton conduction materials to improve SOFC’s performance is one of them. Present work evaluated the viability of compound Ba5Nb4O15 (BNO) as a candidate to produce SOFC’s elements. This compound show a hexagonal perovskite structure and recent papers point this kind of structure is currently used can show some indications of proton conduction. At present study, it was evaluated BNO synthesis through an alternate method to solid-state reaction, based on Pechini method and using different oxides as precursors. Since there are many different processing routes to obtain this phase, it was compared sinterability of synthesized powders after pressing and sintering at two temperatures: 1400 and 1450ºC. The poisoning effect of titanium and zirconium on structure and electric properties was also studied. BNO phase was successful obtained in all synthesis, although non-stoichiometry phases were present on Pechini sample after first calcination; after sintering, these phases were no longer present though. A higher densification was obtained after milling synthesized powder previously to pressing: a bulk porosity smaller than 5% was achieved. Doping produce grain refinement, but it was not efficient improving electrical conductivity. However, sintered samples at 1450ºC had shown higher conductivity on humid atmosphere (H2O) than presented on heavy water atmosphere (D2O). This could be an indication of proton conductionin this structure. Keywords: proton conduction, hexagonal perovskites, Pechini method, solid oxide fuel cells.