Les liposomes sont des nanovecteurs polyvalents et prometteurs quant à leur utilisation dans plusieurs domaines. Il y a une décennie, un nouveau type de liposome constitué d’amphiphiles monoalkylés et de stérols est né fortuitement dans notre groupe. Ils sont nommés Stérosomes puisqu’ils contiennent une grande proportion de stérols, entre 50 et 70 mol %. Les objectifs de cette thèse sont de développer de nouvelles formulations de Stérosomes ayant des caractéristiques spécifiques et d’acquérir une compréhension plus profonde des règles physicochimiques qui dictent leur comportement de phase. Nous avons spécifiquement examiné le rôle de motifs moléculaires des stérols, de la charge interfaciale et de la capacité à former des liaisons H dans les interactions intermoléculaires menant à l’autoassemblage. Le comportement de phase a été caractérisé par calorimétrie différentielle à balayage (DSC), par spectroscopie infrarouge (IR) et par spectroscopie de résonance magnétique nucléaire du deutérium (²H NMR). Premièrement, nous avons établi certaines corrélations entre la structure des stérols, leur tendance à former des bicouches fluides en présence d'amphiphile monoalkylé et la perméabilité des grandes vésicules unilamellaires (LUV) formées. La nature des stérols module les propriétés de mélange avec de l’acide palmitique (PA). Les stérols portant une chaîne volumineuse en position C17 sont moins aptes à induire des bicouches fluides que ceux qui ont une chaîne plus simple, comme celle du cholestérol. Un grand ordre de la chaîne alkyle de PA est un effet commun à tous les stérols investigués. Il a été démontré que la perméabilité des LUV peut être contrôlée en utilisant des stérols différents. Cependant, ces stérols n’ont aucun impact significatif sur la sensibilité des Stérosomes au pH. Afin de créer des liposomes qui sont sensibles au pH et qui ont une charge positive à la surface, des Stérosomes composés de stéarylamine et de cholestérol (Chol) ont été conçus et caractérisés. Il a été conclu que l’état de protonation de l’amine, dans ce travail, ou du groupe carboxylique, dans un travail précédent, confère une sensibilité au pH et détermine la charge à la surface du liposome. Les premiers Stérosomes complètement neutres ont été fabriqués en utilisant un réseau de fortes liaisons H intermoléculaires. Le groupe sulfoxyde est capable de former de fortes liaisons H avec le cholestérol et les molécules d’eau. Une bicouche fluide métastable a été obtenue, à la température de la pièce, à partir d'un mélange équimolaire d’octadécyl méthyl sulfoxyde (OMSO) et de Chol. Ce comportement distinct a permis d’extruder le mélange pour former des LUV à la température de la pièce. Après 30 h, le temps de vie de la phase métastable, des Stérosomes stables et imperméables existaient toujours sous une forme solide. Un diagramme de température-composition a été proposé afin de résumer le comportement de phase des mélanges d’OMSO/Chol. Finalement, nous avons élaboré des Stérosomes furtifs en incorporant du polyéthylène glycol (PEG) avec une ancre de cholestérol (PEG-Chol) à l’interface de Stérosomes de PA/Chol. Jusqu’à 20 mol % de PEG-Chol peut être introduit sans perturber la structure de la bicouche. La présence du PEG-Chol n’a aucun impact significatif sur la perméabilité de la LUV. L'encapsulation active de la doxorubicine, un médicament contre le cancer, a été réalisée malgré la faible perméabilité de ces LUV et la présence du PEG à l’interface. L’inclusion de PEG a modifié considérablement les propriétés de l’interface et a diminué la libération induite par la variation de pH observée avec des LUV nues de PA/Chol. Cette formulation inédite est potentiellement utile pour l’administration intraveineuse de médicaments. / Liposomes are promising and versatile nanocarriers suitable for potential applications in many fields. A decade ago, a new type of liposomes formed from monoalkylated amphiphiles and sterols was born somehow fortuitously in our group. They are referred to as Sterosomes, because they contain a large proportion of sterols, between 50 and 70 mol %. The objectives of the present thesis are to develop novel Sterosome formulations with specific features, and to gain a deeper understanding of the physicochemical rules that dictate their phase behavior. We have specifically examined the role of the molecular features of sterols, of the interfacial charges and of the H-bond capacity in the intermolecular interactions leading to the self-assembly. The phase behavior was characterized by differential scanning calorimetry (DSC), infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy of deuterium (2H NMR). First, we have established some correlations between the structure of the sterols, the propensity to form fluid bilayers, and the permeability of the resulting large unilamellar vesicles (LUVs). The nature of the sterol modulates the properties of the mixture with palmitic acid (PA). Sterols bearing a bulky tail chain at C17 are less capable to induce fluid bilayers than those with a non-bulky tail chain, like that of cholesterol. A large ordering of the alkyl chain of PA is an effect exhibited by all of the investigated sterols. It is shown that the permeability of the LUVs can be controlled using different sterols. However, these sterols have no significant impact on the pH-sensitivity of Sterosomes. In order to create liposomes that are pH-sensitive and that have a positive surface charge, Sterosomes composed of stearylamine and cholesterol (Chol) were designed and characterized. It is concluded that the protonation/deprotonation state of the amine (in this work) and carboxylic acid (in previous work) groups confers the pH-sensitivity and determines the surface charge of the liposomes. The first completely neutral Sterosomes were crafted based on the creation of strong intermolecular hydrogen bond networks. The sulfoxide group was capable of forming strong hydrogen bonds with cholesterol and water molecules. In an equimolar octadecyl methyl sulfoxide (OMSO)/Chol mixture, a metastable fluid bilayer was obtained at room temperature. This distinct phase behavior allowed extruding the mixtures to form LUVs at room temperature. After 30 h, the life-time of the metastable phase, stable and impermeable Sterosomes still existed in the solid form. A temperature–composition diagram was proposed to summarize the phase behavior of OMSO/Chol mixtures. Finally, a further step was made to prepare “stealth” Sterosomes by incorporating polyethylene glycol (PEG) with a cholesterol anchor (PEG-Chol) at the interface of PA/Chol Sterosomes. Up to 20 mol % PEG-Chol can be introduced without disturbing the bilayer structure. The presence of PEG-Chol had no significant impact on the permeability of the resulting LUVs. Active-loading of an anti-cancer drug, doxorubicin, can be achieved despite the low permeability of these LUVs and the presence of the PEG at the interface. The inclusion of PEG modified considerably the interface properties and decreased significantly the pH-triggered release observed with naked PA/Chol LUVs. This novel formulation is potentially useful for the application of intravenous administration in the drug delivery field.

Processing of Bolu-Himmetoglu (Type I Kerogen) and Ankara-Beypazari (Type II Kerogen) oil shales by flotation techniques were investigated for achieving clean solid fuel substitutes. Materials characterization was done through mineralogical, XRD and FTIR analyses. Flotation responses of the samples were tested with non-ionizing and ionizing collectors of cationic and anionic types. The effects of the collector dosage and pulp pH on cleaning were determined. Other important flotation parameters, conditioning time, flotation time, pulp density, particle size and frother dosage were encountered using a statistical approach, through a full two level factorial experimental design. An advanced flotation procedure, assisted by ultrasonic application, was developed for further improvement in flotation performance. The effects of cleaning on thermal characterstics and combustion kinetics were evaluated with Differential Scanning Calorimetry and ASTM methods while the changes in the emission profiles were assessed using Effluent Gas Analysis. Himmetoglu sample was characterized as a carbonate and organic rich humic oil shale with XRD and FTIR analyses while Beypazari oil shale involved significant carbonate and clay minerals and exhibited a fulvic character with a poor organics content. Reverse flotation with amine acetates provided the most effective means of cleaning with Himmetoglu oil shale. Ash was decreased from 34.76 % to 23.52 % with a combustible recovery of 83.57 % using 800 g/ton Flotigam CA at natural pH and the calorific value increased from 4312 kcal/kg to 5010 kcal/kg. Direct flotation with amines was most effective for Beypazari oil shale cleaning. Using Armoflote 17, ash was reduced from 69.88 % to 53.10 % with 58.64 % combustible recovery using 800 g/ton Armoflote 17 at natural pulp pH and the calorific value of the sample increased from 876 kcal/kg to 2046 kcal/kg. Following optimization, ash of Himmetoglu oil shale decreased to 16.81 % with 84.10 % combustible recovery and calorific value increased to 5564 kcal/kg. For Beypazari oil shale ash decreased to % 48.42 with 59.17 % combustible recovery and the calorific value increased to 2364 kcal/kg. Ultrasonic pre-treatment before flotation further decreased the ash of Himmetoglu sample to 11.82 % with 82.66 % combustible recovery at 15 minutes pre-conditioning time and 50 % power level. For Beypazari oil shale, ash decreased to 34.76 % with 64.78 % combustible recovery after 15 minutes pre-treatment time at 70 % power level. Comparative XRD spectra and SEM analyses revealed that the extent of mineral matter removal relied on the flotation performance. The thermal indicators considerably improved after cleaning and the extent of improvement increased with a decrease in the ash of the concentrates. Kinetic analysis showed the favorable effect of inorganics removal on the effectiveness and easiness of combustion and activation energies decreased after cleaning for both oil shales. The contributions of cleaning on the effectiveness of combustion were also revealed by the increases in the emission rates and total CO2 and CO emission amounts. CO2 emissions due to mineral matter decomposition and harmful SO2 emissions apparently decreased as a consequence of the cleaning of the undesired inorganic contituents and potentially cleaning components. Results of the cleaning and thermal analysis sudies revealed that it was possible to achieve a clean energy source alternative from oil shales through flotation and a significant potential can be anticipated for future use of oil shales as a cost effective and environmental friendly solid fuel substitute in view of Turkey&amp / #8217 / s great oil shale reserves.

Τα Νανοσύνθετα συστήματα πολυμερικής μήτρας – σιδηροηλεκτρικών ή πιεζοηλεκτρικών σωματιδίων (κεραμικά εγκλείσματα) αναμένεται να αποτελέσουν μια νέα γενιά υψηλού τεχνολογικού ενδιαφέροντος που θα επιδεικνύουν λειτουργικές ιδιότητες λόγω της ποικίλης πόλωσης των κεραμικών νανοσωματιδίων. Η διασπορά κεραμικών εγκλεισμάτων στο εσωτερικό πολυμερικής μήτρας προσδίδει στα σύνθετα συστήματα βελτιωμένη μηχανική και ηλεκτρική συμπεριφορά. Τέτοιου τύπου συστήματα υλικών, που έχουν υψηλή ηλεκτρική διαπερατότητα (high-Κ materials) χρησιμοποιούνται σε ηλεκτρονικές εφαρμογές, καθώς μειώνουν τα ρεύματα διαρροής και παράλληλα λειτουργούν ως ενσωματωμένοι νανο-πυκνωτές και αισθητήρες ακουστικών εκπομπών. Η ηλεκτρική απόκριση τους, εκφράζεται κυρίως μέσω της ηλεκτρικής διαπερατότητας και μπορεί να ρυθμιστεί, ελέγχοντας τον τύπο, το μέγεθος και την ποσότητα της κεραμικής ενίσχυσης. Η ενσωμάτωση σιδηροηλεκτρικών ή πιεζοηλεκτρικών κρυστάλλων, που επιδεικνύουν υψηλή πόλωση, σε μια πολυμερική μήτρα, όπως η εποξειδική ρητίνη – που εν γένει είναι ηλεκτρικός μονωτής- με χαμηλή ηλεκτρική διαπερατότητα και υψηλή διηλεκτρική αντοχή μπορεί να οδηγήσει στην ανάπτυξη ενός ευφυούς συστήματος. Σκοπός αυτής της εργασίας είναι η παρασκευή και ο χαρακτηρισμός σύνθετων πολυμερικών συστημάτων εποξειδικής ρητίνης – νανοσωματιδίων τιτανικού ψευδάργυρου (ZnTiO3) καθώς και σύνθετων υβριδικών συστημάτων εποξειδικής ρητίνης - νανοσωματιδίων τιτανικού ψευδάργυρου (ZnTiO3) και τιτανικού βαρίου (BaTiO3) ώστε να οδηγηθούμε σε ένα σύστημα υλικών με βέλτιστη συμπεριφορά. Στο θεωρητικό κομμάτι αυτής της εργασίας συζητούνται βασικές έννοιες και θεωρίες που αφορούν τα σύνθετα υλικά, τη θεωρία των διηλεκτρικών και ενεργών διηλεκτρικών, την ηλεκτρική συμπεριφορά σύνθετων υλικών με πολυμερική μήτρα καθώς και πειραματικές τεχνικές χαρακτηρισμού. Στο πειραματικό μέρος, νανοσύνθετα πολυμερικά συστήματα παρασκευάστηκαν από εποξειδική ρητίνη και νανοσωματίδια ZnTiO3 και BaTiO3. Η μέση διάμετρος σωματιδίων βάσει των προδιαγραφών του προμηθευτή ήταν λιγότερο από 100nm για το ZnTiO3 και στην περιοχή των 30 - 50nm για το BaTiO3. Στη συνέχεια τα νανοσύνθετα υποβλήθηκαν σε μορφολογικό, θερμικό και ηλεκτρικό χαρακτηρισμό. Η μορφολογία των δειγμάτων εξετάστηκε για τυχούσα παρουσία κενών (voids) και συσσωματωμάτων (clusters) μέσω του Ηλεκτρονικού Μικροσκοπίου Σάρωσης (SEM) και η θερμική τους απόκριση μέσω της Διαφορικής Θερμιδομετρίας Σάρωσης (DSC). Η διασπορά των κεραμικών εγκλεισμάτων θεωρήθηκε ικανοποιητική, παρόλο που συνυπάρχουν οι νανοδιασπορές με συσσωματώματα. Οι διηλεκτρικές ιδιότητες και τα σχετιζόμενα φαινόμενα διεργασιών χαλάρωσης μελετήθηκαν με χρήση της Διηλεκτρικής Φασματοσκοπίας Ευρέως Φάσματος (BDS) στο εύρος θερμοκρασιών -100 oC έως 160 oC και στο διάστημα συχνοτήτων 10-1 Hz έως 106 Hz. Η ανάλυση των πειραματικών αποτελεσμάτων διεξήχθη με τη χρήση των φορμαλισμών της ηλεκτρικής διαπερατότητας και του ηλεκτρικού μέτρου. Από τα πειραματικά αποτελέσματα προκύπτει πως παρατηρούνται διηλεκτρικές χαλαρώσεις που οφείλονται τόσο στην πολυμερική μήτρα, όσο και στην ενισχυτική φάση. Τα φάσματα των υβριδικών συστημάτων καταγράφουν τουλάχιστον τέσσερεις διακριτούς τρόπους χαλάρωσης. Αυτά αποδίδονται στη διεπιφανειακή πόλωση (Interfacial Polarization ή φαινόμενο MWS) μήτρας/εγκλεισμάτων, στην α- χαλάρωση λόγω υαλώδους μετάβασης του πολυμερούς και στην β- και γ- χαλάρωση εξαιτίας της κίνησης πλευρικών πολικών ομάδων και τοπικής κίνησης μικρών τμημάτων της πολυμερικής αλυσίδας. Η λειτουργικότητα των νανοσύνθετων σχετίζεται με την μεταβολή της πόλωσης, που σχετίζεται ευθέως με το πραγματικό μέρος της ηλεκτρικής διαπερατότητας, την εξάρτηση της ειδικής αγωγιμότητας από την θερμοκρασία και την περιεκτικότητα σε ενισχυτικό μέσο και την δυνατότητα αποθήκευσης ενέργειας. / Nanocomposite systems, which include ferroelectric or piezoelectric particles represent a novel class of materials which are expected to exhibit functional properties because of the varying polarization of the ceramic particles. Dispersing ceramic inclusions within a polymer matrix, results in enhanced mechanical and electrical behavior. Such material systems exhibiting enhanced electrical response are used in electronic applications, for the reduction of leakage currents, as integrated nano- capacitors and as acoustic emission sensors. The electrical response of these composites, namely dielectric permittivity and conductivity can be tailored, by controlling the type, the size and the amount of ceramic inclusions. The ceramic filler could be ferroelectric and/or piezoelectric crystal particles. Their high level of polarization can be combined with a polymer host, like an epoxy resin – which is, in general, electrical insulator – with low dielectric permittivity and high dielectric breakdown strength. This combination could lead in the development of a smart materials’ system. The aims of this work are the preparation and characterization of epoxy resin nanocomposites with embedded zinc titanate (ZnTiO3) and nanoparticles and in tandem hybrid system of epoxy resin– zinc titanate (ZnTiO3) and barium titanate (BaTiO3) nanoparticles. In the first part of this work basic aspects concerning composite materials, dielectric theory, electrical behaviour and characterization techniques of polymer matrix composites are presented. In the experimental part of this study, nanocomposites were prepared by employing commercially available materials such as epoxy resin, ceramic ZnTiO3 and BaTiO3 nanopowder. The mean particle diameter, as indicated by the supplier, was less than 100nm for ZnTiO3 and 30-50nm for BaTiO3 particles. Furthermore, morphology, thermal and electrical response of the produced specimens was examined. The morphology of the specimens was checked for voids and clusters, by means of Scanning Electron Microscopy and the thermal response via Differential Scanning Calorimetry (DSC). Ceramic particles distribution is considered as satisfactory, although clusters co-exist with nanodispersions in all the examined systems. The dielectric properties and the related relaxation phenomena were studied by means of Broadband Dielectric Spectroscopy (BDS) in the temperature range from -100 oC to 160 oC and frequency range from 10-1 Hz to 10-6 Hz. Experimental data analysis was conducted by means of dielectric permittivity and electric modulus formalisms. Based on the conducted analysis, the recorded relaxation phenomena include contributions from both the polymeric matrix and the reinforcing phase. In the spectra of hybrid nanocomposites at least four relaxation processes can be detected. They were attributed to Interfacial Polarization phenomenon (MWS effect), α-mode due to glass/rubber transition of the polymer and β- , γ- modes resulting from the motion of polar side groups and local motion of small segments of the polymer chain. The functionality of the nanocomposite systems is related to the variation of polarization, which is directly connected to the real part of dielectric permittivity, the dependence of conductivity on the temperature and the filler content, and the energy storage efficiency expressed by the density of energy.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-08T19:05:31Z No. of bitstreams: 1 TACIANO PESSOA – TESE (PPGEP) 2015.pdf: 1372058 bytes, checksum: e953b936619e36c851136deb1ffc76af (MD5) / Made available in DSpace on 2018-06-08T19:05:31Z (GMT). No. of bitstreams: 1 TACIANO PESSOA – TESE (PPGEP) 2015.pdf: 1372058 bytes, checksum: e953b936619e36c851136deb1ffc76af (MD5) Previous issue date: 2015-08 / Realizou-se esta pesquisa com o objetivo de produzir palitos de inhame fritos em óleos de coco e de soja, estabelecendo parâmetros comparativos de qualidade nutricional e sensorial. Para obtenção do óleo de coco, foi realizada uma prensagem a frio, após estudo de secagem das tiras de coco em estufa a 60 e 70°C, que foram ajustadas as equações matemáticas de Cavalcanti Mata, Handerson & Pabis, Page, Verma e modelo difusional de Fick 4 termos. A caracterização dos óleos utilizados, avaliados antes e após as frituras quanto ao teor de água, índices de acidez, peróxido, refração, iodo, saponificação e calorimetria diferencial de varredura (DSC). Os palitos de inhame foram pré tratados em soluçõ es osmóticas salinas, contendo 5, 10 e 15% de sal (NaCl), onde realizou-se a cinética de desidratação osmotica, que pode-se calcular as perdas de massa e ganho de sólidos das amostras, em seguida foram fritos em óleo de coco e de soja, nas temperaturas de 150, 170 e 190°C, em que foram avaliados as características químicas e físico-químicas dos palitos de inhame In natura, após DO e frituras, quanto aos parâmetros: acidez, pH, atividade de água, teor de água, lipídeos, teor de sódio, teor de amido, absorção de gordura, remoção de água, razão de absorção de gordura. Para a cor (L, a e b) e textura instrumental os parâmetros: firmeza, coesividade, elasticidade e mastigabilidade . Para verificar a aceitação do produto, as amostras foram fritas a 190°C em seguida submetidas a análise sensorial. Concluiu-se que: A equação matemática de secagem proposta Cavalcanti Mata é, dentre aqueles testados, o que apresenta melhor ajuste sendo o selecionado para a representação da cinética dos palitos de coco; As características de identidades do óleo de soja analisado, apresentaram-se dentro dos padrões exigidos para os índices de acidez, peróxido, iodo, refração e saponificação; As caraterísticas de identidade do óleo de coco, apresentou-se dentro dos padrões estabelecidos para os índices de acidez, peróxido e refração; O DSC permitiu verificar o seu desempenho térmico de oxidação com evento exotérmico em pico a 238,3 e 237,8°C, para o óleo de coco e de soja respectivamente; O índice de peróxido dos óleos utilizados nas frituras de 150°C ocorre um aumento do índice avaliado, com o aumento do número de frituras, o óleo de soja apresenta valores superiores a 8,494 (meq/1000 de óleo) quanto aos observados no óleo de coco valores menores que 4,244 (meq/1000 de óleo), que o torna indesejado para o consumo, quando se compara a legislação brasileira; O aumento da concentração de sal nas soluções favoreceu para uma maior perda de peso e ganho de sólidos dos palitos de inhame; Para a razão de absorção de gordura (RAG) amostras fritas com óleo de coco apresentaram menores valores de RAG. O aumento das temperaturas de fritura das amostras, tenderam apresentar menores valores de RAG; A textura instrumental dos palitos de inhame fritos, obtiveram influencias direta do tratamentos osmóticos, óleo e temperatura utilizados na fritura; Com base no perfil de atitude dos consumidores, pode-se concluir que as amostras que apresentaram maior aceitação foram: os palitos de inhame fritos em óleo de coco pré tratados com desidrat ação osmótica a 15% de solução salina, para os palitos de inhame fritos em óleo de soja, foram as amostras tratadas com desidratação osmótica a 10 e 15% de solução salina. Considerando os resultados obtidos na pesquisa para a produção de palitos de inhame frito, conclui-se que a união de matérias primas permitiu originar um produto com quam lidade sensorial e acessibilidade para o mercado consumidor. / Carried out this search in order to produce fried yams sticks coconut and soy oils, establishing comparative parameters of nutritional and sensory quality. To obtain coconut oil a cold pressing was performed after drying study of coconut strips in a greenhouse at 60 to 70 ° C, which were adjusted mathematical equations Cavalcanti Woods, Handerson & Pabis, Page Verma and model diffusive Fick 4 terms. The characterization of the oils used, evaluated before and after frying as the water content, acidity index, peroxide, refraction, iodine, saponification and differential scanning calorimetry (DSC). Yam sticks were pretreated with saline osmotic solutions containing 5, 10 and 15% salt (NaCl), which was he ld osmotic dehydration kinetics, which can calculate the mass loss and solid gain of sample then they were fried in coconut oil and soybean oil at temperatures of 150, 170 and 190°C, which evaluated the chemical and physicochemical characteristics of yam sticks in natura after DO and fried foods, as the parameters : acidity, pH, water activity, water content, lipids, sodium content, starch content, fat absorption, water removal rate of fat absorption. For color (L, a and b) and instrumental texture parameters: firmness, cohesiveness, springiness and chewiness. To verify acceptance of the product, samples were fried at 190°C and then subjected to sensory analysis. It was concluded that: The mathematical equation drying proposal Cavalcanti Mata is among thos e tested, which fits better being selected to represent the kinetics of coconut sticks; The characteristics of soybean oil identities analyzed were within the standards required for the acid values, peroxide, iodine, refraction and saponification The ident ity characteristics of coconut oil, was within the standards established for the acidity index, peroxide and refraction; The DSC has shown this thermal oxidation performance with peak exothermic event at 238.3 and 237.8 ° C for coconut oil and soybean oil, respectively; The peroxide value of the oils used in the frying of 150 ° C an increase of the estimated index, with increase of fried foods, soybean oil exhibited superior values 8.494 (meq / 1000 oil) as those observed in the oil coconut values less than 4,244 (mEq / 1000 oil) which makes it undesirable for consumption, when comparing the Brazilian legislation; Increasing the salt concentration in the solution favored for greater weight loss and gain the yams solid sticks; For the reason of fat absorption (RAG) chips with coconut oil samples showed lower values RAG. The increase in frying temperatures of the samples tended RAG have lower values; The instrumental texture of fried yam sticks, obtained direct influence of osmotic treatments, oil and temperature used for frying; Based on consumer attitude profile, it can be concluded that the samples had higher acceptance were fried yams sticks pre coconut oil treated with osmotic dehydration at 15% saline to fried yams sticks in soybean oil samples were treated with osmotic dehydration at 10 and 15% saline. Considering the results obtained in the research for the production of fried yam sticks, concluded that the union of raw materials allowed yield a product with sensory quality and affordability for the consumer market.

Dans leurs usages courants comme isolants électriques, les matériaux solides organiques sont constitutifs aussi bien des câbles de transport d'énergie électrique, des circuits de commande et de conversion de puissance que des composants (micro)électroniques ou des systèmes embarqués (revêtement thermique des satellites, batteries d'accumulateurs...). La diversité des contraintes d'utilisation auxquelles ils sont soumis (champ électrique, rayonnement, température, humidité...) les prédisposent à emmagasiner des charges en leur sein, susceptibles d'affecter la fiabilité des systèmes qui en dépendent. L'un des moyens communément mis en œuvre pour étudier le comportement électrique de ces charges est la mesure de la distribution spatio-temporelle des charges d'espace, en soumettant le diélectrique à une différence de potentiel continue à travers deux électrodes. Cette méthode ne permet cependant pas toujours de distinguer clairement la contribution des charges dues à la génération, d'une part, et celles dues aux phénomènes de transport, d'autre part. Cette étude propose une approche alternative, consistant à déposer sous vide des charges (électrons) au sein de l'isolant par le biais d'un faisceau d'électrons, à une position connue et en quantité maîtrisée, en prenant en compte d'autres processus physiques liés à l'implantation d'électrons afin de prévoir et modéliser le comportement de ces matériaux irradiés. Des films de PolyEthylène basse densité (PEbd), préparés par thermomoulage, ont été irradiés par un faisceau d'électrons de 80 keV avec un flux de 1 nA/cm2. Les mesures de charge d'espace par la méthode Electro-Acoustique Pulsée (PEA), réalisées d'abord in-situ, puis ex-situ sous polarisation électrique DC, confirment une localisation effective de charges au sein du matériau. Les résultats sous polarisation électrique après irradiation mettent en évidence une importante présence de charges positives dans la zone irradiée du diélectrique. Les caractérisations électriques des films PEbd irradiés montrent un comportement complètement différent de celui d'un même matériau non-irradié, laissant penser à une modification de la structure chimique du matériau. Des mesures physico-chimiques (spectroscopie infra-rouge, Photoluminescence et Analyse Enthalpique Différentielle-DSC) sur ces films PEbd irradiés, ne montrent pas une dégradation significative de la structure chimique du diélectrique qui expliquerait le comportement électrique observé sous polarisation post-irradiation. Des mesures complémentaires montrent le comportement réversible du PEbd irradié puis polarisé, qui serait uniquement lié à la présence des charges générées par le faisceau. Les données expérimentales de cette étude ont parallèlement alimenté un modèle numérique de transport de charges, développé pour tenir compte des contraintes sous irradiation. Ce modèle a permis de reproduire les résultats d'implantation de charge par faisceau d'électrons in-situ ainsi que la majorité des processus électriques observés sur du PEbd irradié puis polarisé. Il confirme l'impact de la charge déposée par faisceau d'électrons sur le comportement sous polarisation et permet de conclure quant à l'origine des charges positives observées post-irradiation, qui seraient dues aussi bien aux phénomènes d'injection aux électrodes qu'à la création de paires électrons/trous par le faisceau d'électrons pendant l'irradiation. / In their common uses as electrical insulators, organic solid materials are constitutive of electric power transmission cables, power control and conversion circuits as well as (micro) electronic components or embedded systems (thermal coating of satellites, batteries of accumulators, etc.). Under various constraints of use (electric field, radiation, temperature, humidity ...) they can accumulate charges in their bulk which could affect the reliability of the systems in which they are employed. One of the commonly used means to study the electrical behavior of these charges is to measure the spatiotemporal distribution of charges by subjecting the dielectrics to a continuous potential difference between two electrodes. However, this method does not always allow clearly distinguishing the contribution of charges due to generation on the one hand and the one due to transport phenomena on the other hand. This study proposes an alternative approach, consisting in generating charges (electrons) within the electrical insulation using an electron-beam under vacuum. The charges are hence deposited at a known position and in a controlled quantity. Other physical processes related to the implantation of electrons must then be taken into account in order to predict and model the behavior of these irradiated materials. Low-density polyethylene (LDPE) films, prepared by thermal molding, were irradiated by a 80 keV electron-beam with a current flux of 1 nA/cm2. Space charge measurements using the Pulsed Electro-Acoustic (PEA) method, performed first in-situ and then ex-situ under DC electrical polarization, confirm an effective localization of charges within the material. The results under electrical polarization after irradiation show an important amount of positive charges in the irradiated zone of the dielectric. The electrical characterizations of irradiated LDPE films show a completely different behavior compared to the same non-irradiated material, suggesting a modification of the chemical structure of the material. Physico-chemical measurements (infrared spectroscopy, Photoluminescence and Differential Scanning Calorimetry-DSC) on these irradiated PEbd films do not show a significant degradation of the chemical structure of the dielectric which would explain the observed electrical behavior under post-irradiation polarization. Additional measurements show the reversible behavior of the irradiated then polarized PEbd, which would be only related to the presence of the charges generated by the beam. The experimental data of this study have simultaneously fed a numerical model of charge transport, developed to take into account the irradiation constraints. This model allows reproducing the in-situ results of charge implantation by the electron beam as well as the majority of the electrical processes observed on irradiated and polarized LDPE. It confirms the impact of the electron-beam deposited charge on the behavior under polarization and allows concluding on the origin of the positive charges observed after irradiation, which would be due to injection at the electrodes as well as to the creation of electron-hole pairs by the electron-beam during irradiation.

Cette étude s’inscrit dans le cadre du projet MINERVE de la région wallonne quivise notamment à valoriser les anciens centres d’enfouissement technique et leur contenuau travers de la production de matières premières et de sources d’énergie. Plus particulièrement,l’objectif de ce travail est d’étudier un procédé de co-pyrolyse de déchetsplastiques et d’huiles de lubrification usagées, ayant pour finalité la production d’uncombustible alternatif liquide pour l’industrie, en vue d’une future montée en échelledu procédé.Pour ce faire, différentes approches ont été poursuivies. Premièrement, nous avonsmis en place un réacteur de 5 litres, agité et scellé hermétiquement, permettant demener des essais de co-pyrolyse. Des essais de co-pyrolyse d’un mélange de déchetsplastiques excavés et d’huiles de lubrification usagées ont été menés dans le réacteur.L’influence des paramètres clés du procédé, tels que la température maximale, la fractionmassique de plastiques dans le mélange ainsi que la vitesse de refroidissement, surle procédé et la qualité du produit fini a été étudiée. Nous avons été en mesure deproduire un combustible alternatif liquide, possédant un pouvoir calorifique d’environ30 MJ/kg, par la co-pyrolyse d’un mélange contenant 60% de plastiques, en chauffantle mélange durant 13 h, en atteignant une température maximale de 387°C et enlaissant la pression au sein du réacteur monter jusqu’environ 30 bars. Les besoins énergétiquesdu procédé ont été évalués à environ 8 MJ/kg de déchets à pyrolyser, grâce àun modèle de transferts thermiques développé pour le système constitué du réacteur deco-pyrolyse. Ensuite, une méthode a été développée pour déterminer le temps de fonted’une particule de plastique en fonction de sa plus petite dimension. L’application decette méthode nous a permis de déterminer que la plus petite dimension maximale quepeuvent avoir les particules de plastiques dans le mélange plastique/huile, pour queleur fusion ne limite pas le procédé de co-pyrolyse, est d’environ 3 cm. Deux analysesthermiques, la thermogravimétrie isotherme et la calorimétrie différentielle à balayage,ont été combinées pour caractériser le craquage thermique et son influence sur plusieurspolymères. L’influence du craquage thermique sur les polymères a été évaluée sur basede l’analyse de la fusion ou de la transition vitreuse du polymère. Les protocole et dispositifexpérimentaux de co-pyrolyse de déchets plastiques et d’huiles de lubrificationusagées à l’échelle du laboratoire ont été adaptés pour pouvoir co-pyrolyser un mélangecontenant du PVC. Différents essais de co-pyrolyse par étapes ont été menés pour évaluerl’influence des paramètres comme l’évolution de la température pendant l’essai, lecontenu en PVC du mélange et le plastique en mélange avec le PVC (LDPE ou PS).Enfin, les interactions qui prennent place entre le LDPE ou le PS et une huile, lorsde leur co-pyrolyse, ont été mises en évidence à l’aide d’essais de thermogravimétriehaute résolution. Nous avons tenté d’expliquer les interactions mises en évidence, grâceà une combinaison d’analyses thermiques permettant de caractériser, voire d’identifier,les produits de décomposition de l’échantillon, en continu ou en fin de chauffe.This study takes part in the MINERVE (Walloon region) which aims at enhancingthe old landfills and valorize their content through the production of raw materials andenergy sources. Specifically, the objective of this work is to study a co-pyrolysis processof waste plastics and used lubrication oils, whose purpose is the production of a liquidalternative fuel for industry, in order to future scaling up the process.To do so, different approaches have been pursued. First, we set up a 5 liter reactor,stirred and hermetically sealed for performing co-pyrolysis tests. Co-pyrolysis tests ofa mixture of excavated plastic wastes and used lubrication oils were performed in thereactor. The influence of key parameters, such as maximum temperature, the massfraction of plastics in the mixture and the cooling rate, on the process and the qualityof the fuel was investigated. We were able to produce a liquid alternative fuel, witha calorific value of about 30 MJ/kg by co-pyrolyzing a mixture containing 60 % ofplastic, heating the mixture for 13 h, reaching a maximum temperature of 387°C anda maximum pressure of about 30 bar. The energy requirements of the process wereevaluated at about 8 MJ per kg of waste through a heat transfer model developed forthe system consisting of the co-pyrolysis reactor. In addition, a method was developedto determine the time of melting of a plastic particle according to its smallest size.The application of this method allowed us to determine that the maximum smallestsize that can have plastic particles in plastic/oil mixture, so that their melting willnot limit the co-pyrolysis process, is about 3 cm. Two thermal analysis techniques,isothermal thermogravimetry and differential scanning calorimetry, were combined tocharacterize the thermal cracking and its influence on several polymers. The influence ofthermal cracking of the polymers was evaluated based on the analysis of the melting orglass transition of the polymer. The experimental protocol and device of waste plasticsand used lubricating oils co-pyrolysis have been adapted to co-pyrolyze a mixturecontaining PVC. Two-step co-pyrolysis tests were performed to evaluate the influenceof parameters such as the evolution of the temperature during the test, the PVCcontent of the mixture and the plastic that is mixed with PVC (LDPE or PS). Finally,interactions that take place between the LDPE or the PS and an oil, when co-pyrolyzed,have been identified with high resolution thermogravimetry experiments. We tried toexplain the identified interactions through a combination of thermal analyzes thatcharacterized or identified the sample decomposition products, continuously duringthe thermal decomposition or at its end. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

The Al-Zn-Mg-Cu (7XXX series) alloys are amongst the strongest aluminum available. However, they are considered unweldable with conventional fusion techniques due to the negative effects that arise with conventional welding, including hydrogen porosity, hot cracking, and stress corrosion cracking. For this reason, friction stir welding has emerged as the preferred technique to weld 7XXX series alloys. Aluminum 7449 is one of the highest strength 7XXX series aluminum alloy. This is due to its higher zinc content, which leads to a higher volume fraction of eta' precipitates. It is typically used in a slight overaged condition since it exhibits better corrosion resistance. In this work, the welds of friction stir welded aluminum 7449 were studied extensively. Specific focus was placed in the heat affected zone (HAZ) and nugget. Thermocouples were used in the heat affected zone for three different depths to obtain thermal profiles as well as cooling/heating profiles. Vicker microhardness testing, transmission electron microscope (TEM), and differential scanning calorimeter (DSC) were used to characterize the welds. Two different tempers of the alloy were used, a low overaged temper and a high overaged temper. A thorough comparison of the two different tempers was done. It was found that highly overaged aluminum 7449 tempers show better properties for friction stir welding. A heat gradient along with a high conducting plate (Cu) used at the bottom of the run, resulted in welds with two separate microstructures in the nugget. Due to the microstructure at the bottom of the nugget, higher strength than the base metal is observed. Furthermore, the effects of natural aging and artificial aging were studied to understand re-precipitation. Large improvements in strength are observed after natural aging throughout the welds, including improvements in the HAZ.

The dissertation thesis deals with the design of the concept and implementation of models of electrical power system elements with regard to the potential of the use of computer programs – simulations. The solution of the thesis focuses on the compliance simulations of power-generating modules according to RfG (Requirements for Generators), as a document which setting out the requirements for the connection of power-generating facilities and also focuses on the issue of smart grids and MAS (Multi-Agent Systems) respectively. The framework of the thesis is thus defined by the area of requirements for power-generating modules according to legislative requirements (not only RfG, but also related standards incl. DSC (Distribution System Code), CSN EN 50438 and CSN EN 50549), requirements for agent functionalities and power-generating module abilities to operate in synchronous and island operation, including transitions between them, the process of synchronization (phasing) and communication between the individual elements of the power system.

This thesis describes the design of universal control unit for BLDC motor powered from airplane power distribution system of 28 V capable of driving motor up to 10 A. The maximal engine power is about 250 W. Important prerequisite is possibility of driving various motor size without needs of changing wiring board using only the configuration in the auxiliary memory unit. To control different motors is enough one unit with one program without any way to interfere to the unit itself.

The task of this thesis is to study the subject of perfusion analysis based on dynamic imaging with T2/T2* contrast. The focus was on the acquisition commonly used for DSC-MRI and especially in the acquisition pulse sequences that use images with different echo time, so called Multi-echo sequence. Principles of dynamic measurement by magnetic resonance imaging, the role of contrast agents and their influence on the relaxation times are described. It also describes the problems perfusion analysis, measurement and mathematical modeling parameters entering to the convolution dependency for getting perfusion parametersIn the experimental part is developed automatic algorithm to gain curves relaxation time T2 *. Next, the synthetic data are created and tested robustness estimate perfusion parameters against noise. In the next phase of work there are compared real scanned objects with using a conversion with T2 * and free of T2*. In the last phase of work is compared influence of length of used echo times on concentration curves and after perfusion analysis influence on resulting perfusion parameters.