Dissertations / Theses on the topic 'Extrusion systems'

Thesis (M.S.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 16, 2008) Includes bibliographical references.

Cette thèse porte sur l’étude des systèmes de lois de conservation couplés par une interface mobile. Un modèle dynamique d’un procédé d’extrusion obtenu à partir des bilans de masse, de taux d’humidité et d’énergie est proposé. Ce modèle exprime le transport de la matière et de la chaleur dans une extrudeuse par des systèmes d’équations hyperboliques définis sur deux domaines complémentaires variant dans le temps. L’évolution des domaines est dictée par une Equation aux Dérivées Ordinaires (EDO) issue du bilan de masse total dans une extrudeuse. Par le principe des applications contractantes l’existence et l’unicité de la solution pour cette classe de système sont prouvées. Le problème de stabilisation de l’interface mobile est aussi abordé en utilisation le formalisme des systèmes à retard. La méthode des caractéristiques permet de représenter le système composé des équations issues du bilan de masse par un système à retard sur l’entrée. Au moyen d’un contrôleur prédictif la position de l’interface est stabilisée autour d’un point équilibre. La dernière partie de ce travail est dédiée à l’étude des systèmes Hamiltoniens à ports frontière couplés par une interface mobile. Ces systèmes augmentés de variables couleur qui sont des fonctions caractéristiques du domaine peuvent s’exprimer comme des systèmes Hamiltoniens à ports frontière
This thesis is devoted to the analysis of Partial Differential Equations (PDEs) which are coupled through a moving interface. The motion of the interface obeys to an Ordinary Differential Equation (ODE) which arises from a conservation law. The first part of this thesis concerns the modelling of an extrusion process based on mass, moisture content and energy balances. These balances laws express heat and homogeneous material transport in an extruder by hyperbolic PDEs which are defined in complementary time-varying domains. The evolution of the coupled domains is given by an ODE which is derived from the conservation of mass in an extruder. In the second part of the manuscript, a mathematical analysis has been performed in order to prove the existence and the uniqueness of solution for such class of systems by mean of contraction mapping principle. The third part of the thesis concerns the transformation of an extrusion process mass balance equations into a particular input delay system framework using characteristics method. Then, the stabilization of the moving interface by a predictor-based controller has been proposed. Finally, an extension of the analysis of moving interface problems to a particular class of systems of conservations laws has been developed. Port-Hamiltonian formulation of systems of two conservation laws defined on two complementary time-varying intervals has been studied. It has been shown that the coupled system is a port-Hamiltonian system augmented with two variables being the characteristic functions of the two spatial domains

De nos jours, les maladies inflammatoires chroniques de l'intestin (MICI) comme la rectocolite hémorragique et la maladie de Crohn touchent près de 200 000 personnes en France. Elles se caractérisent par l'inflammation de la paroi de différentes régions du tractus gastro-intestinal (TGI). Les deux sont des maladies chroniques qui impliquent une inflammation de la muqueuse colique. La principale différence entre la maladie de Crohn et la rectocolite hémorragique réside dans la localisation et la nature de l’inflammation. La maladie de Crohn peut toucher n’importe quelle partie du tractus gastro-intestinal (TGI), de la bouche à l’anus, mais dans la plupart des cas, elle atteint l’iléon. En revanche, la rectocolite hémorragique est limitée au côlon et au rectum.Le ciblage du colon peut offrir des avantages majeurs pour le traitement des MICI. Les formes galéniques conventionnelles entraînent une libération prématurée de la substance active dans l'estomac et l’intestin grêle. La substance active est alors absorbée dans la circulation sanguine ce qui provoque de sérieux effets secondaires. De ce fait la concentration de substance active qui arrive au site d’action (partie distale du TGI) est très faible, ce qui entraîne une faible efficacité thérapeutique voire échec de la thérapie.Pour pallier ce problème, une forme galénique idéale devrait effectivement protéger la substance active dans le haut TGI, puis la libérer dans la partie distale du TGI de manière contrôlée. Des systèmes réservoirs (granules enrobés, capsules…) ou des systèmes matriciels (comprimés, extrudats…) peuvent être utilisés pour protéger la substance active dans le haut TGI. Les polysaccharides qui ne sont dégradés que par des enzymes bactériennes localisées dans le colon peuvent être utilisés dans le développement des formes galéniques pour le traitement des MICI. L’objectif de ce travail était de développer de nouvelles formes galéniques contenant un polysaccharide (pectine, gomme de guar…) dégradable par la flore colique et d’un polymère thermoplastique hydrophobe (éthylcellulose, HPMC…) qui vas réduire l’hydrophilicité du polysaccharide. Or, le mélange des deux polymères ne doit pas enrober le polysaccharide qui va servir pour le ciblage de la partie distale du TGI
Chronic inflammatory bowel diseases (IBD) today affects close to 200,000 people in France. They are characterized by the inflammation of the wall of a part of the digestive tract. They usually include Ulcerative Colitis and Crohn’s disease. Both are chronic diseases that involve inflammation of the colonic mucosa. The main difference between Crohn’s disease and Ulcerative Colitis is the location and nature of inflammation. Crohn’s disease can affect any part of the GIT from mouth to anus but in most cases attacks the terminal ileum. In contrast, Ulcerative Colitis is restricted to the colon and the rectum. An ideal dosage form should effectively protect the drug in the stomach and small intestine and subsequently release the drug in the colon in a targeted and controlled manner. The objective of this work was to develop new drug delivery systems containing a polysaccharide (pectin, guar gum, inulin ...), which are degradable by the colonic bacteria and a hydrophobic thermoplastic polymer (ethylcellulose, polyurethane, polyvinyl acetate ...), which will reduce the hydrophilicity of the polysaccharide. The technique used for the preparation of these dosage forms is hot-melt extrusion. It is a continuous and free solvent process that allows the manufacturing of a dosage form called "extrudate" by forcing the soften material through an orifice. It has been demonstrated that extrudates based on polyvinyl acetate/polyurethane and inulin can minimize the release of a model active substance in the upper part of GIT due to the hydrophobic properties of polyvinyl acetate. Indeed, these extrudates uptake low amount of water and lose low dry mass upon exposure to media simulating the stomach and the small intestine. However, once in contact with the colonic flora, these systems show a considerable loss of mass due to the degradation of inulin by enzymes secreted by colonic bacteria. In another study, hot melt extrudates based on ethylcellulose blended with different types of polysaccharides (guar gum, inulin, corn starch, maltodextrin, pectin and chitosan) were studied for the development of controlled drug delivery systems. Anhydrous theophylline and diprophylline have been used as model drugs. This study was useful to set the extrusion parameters: temperature 100 °C; screw speed 30 rpm; feed rate 3 cc/min; 30 % dibutyl sebacate as a plasticizer. Importantly, hot melt extrudates based on ethylcellulose:guar gum blends offer an interesting potential as controlled drug delivery systems: They can be prepared at temperatures of about 100 °C, provide broad spectra of drug release patterns (in particular about constant drug release rates). Finally, hot melt extrudates remained stable after 1 year storage at ambient conditions

Compression of coated pellets is a practical alternative to capsule filling. The current practice is to add cushioning agents to minimize the stress on the coated pellets. Cushioning agents however add bulkiness and reduce the overall drug loading capacity. In this study, we investigated the performance of compressed coated pellets with no cushioning agent to evaluate the feasibility of predicting the coat behaviour using thermo-mechanical and rheological analysis techniques. Different coating formulations were made of ethyl cellulose (EC) as a coating polymer and two different kinds of additives were incorporated into the polymeric coating solution. Triethyl Citrate (TEC) and Polyethylene glycol 400(PEG400) were used as plasticizers at different levels to the coating formulations (10%, 20%, 30%). Thermal, mechanical and rheological measurements of the coating film formulations were achieved to investigate the effect of plasticizers. Thermal gravimetric analysis results (TGA) showed higher residual moisture content in films plasticised with PEG 400 compared to their TEC counterparts. Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and Parallel Plate Shear Rheometer (PPSR) were used to study the influence of the level and type of plasticisers incorporated in coating film formulation on the performance of the coating film. In this study, both DSC and DMA were used to investigate the Tg for each film coating formulation in order to evaluate the effect of the additives. In general DMA results for the Tg value of the films were always higher by 10-20% than those measured by the DSC. Furthermore, clamp size and the frequency of the oscillation have an influence on the evaluation of Tg. Complex viscosity for different coating film formulations revealed that the shear hinning gradient changes with temperature and plasticiser type and concentration. The value of complex viscosity from DMA and PPSR exhibits power law behaviour. The rheological moduli were indirectly affected by the level of plasticiser. There was a discrepancy between the complex viscosity results obtained from both DMA and PPSR at similar temperature but they follow the same trend. The non plasticized polymer showed a 10 time higher complex viscosity values when measured by DMA over that measured by PPSR. The difference was smaller in plasticized films but it was not consistent. Therefore a consistent coefficient to correlate the DMA and PPSR couldn’t be accurately determined Coated pellets were compressed and key process parameters were evaluated. The obtained results revealed that the coating thickness has a significant effect on the release profile of the final products. It was found that by increasing the coating film thickness, the percentage released decreased. Also the compression force has lower influence on the drug release profile, while the dwell time has very low effect on the percentage release from the final products. Optimum release profile was obtained at a coating level of 5.5% w/w and a compression force of 4700N In conclusion, the elasticity of the plasticised EC films in this study meant that the internal stress is not dissipated during compression and the dwell time range that was used in this experiment. Increasing the thickness therefore was necessary to enhance the strength of the film and avoid cracking. The mechanical and rheological profiling was helpful therefore to understand the behaviour of the coated pellets and predict the film properties at various steps of the process of coating and compression (i.e., various shear rate regimes). Experimental design approach to studying the key process and formulation parameters helped identify the optimum values for the process.

The inflammatory arthritis Ankylosing Spondylitis (AS) is linked to the human leucocyte antigen HLA-B27. HLA-B27 is thought to drive AS because it misfolds during assembly in the endoplasmic reticulum (ER), inducing ER cell stress. Modulating HLA-B27 folding in the ER is therefore a therapeutic target pathway. The recent discovery of polymorphisms in the ER-resident peptidase ERAP1 that can impact on HLA-B27 and AS, makes ERAP1 one such target. Exosomes are small, typically 50-200 nm sized particles, formed in the endosomal recycling pathway, which can be released into the extracellular environment. Exosomes have a wide range of biological activities depending on the cell type of origin, and on the delivered cargo, which can include bio-active proteins, lipids, mRNA and miRNA. There is interest in the use of exosomes as drug delivery agents. Here, exosomes were studied as a delivery agent to modulate ERAP1, as a potential therapeutic tool for the treatment of AS. Exosomes, isolated from cell lines including CEM and Jurkat (T cell lineage), Jesthom (B cell lineage), U937 (monocyte lineage) and the epithelial HeLa cell line, were characterized by nanoparticle tracking analysis, flow cytometry and immunoblotting using markers including CD9, CD63, CD81 and TSG101. Differential expression of these markers in the immune cell lines indicated the complexity of defining exosomes. EVs were then tested using cell penetrating peptides, electroporation, lipid transfection and sonication for their ability to load FITC-siRNA or FITC-antibody as cargo. Significantly, post-loading RNase A or trypsin incubation demonstrated that many techniques do not lead to efficient cargo loading of exosomes. Sonication proved the most effective technique, with up to 30% efficiency. Loading of exosomes with ERAP1-targetted siRNA did not however lead to notable ERAP1 inhibition. The data indicates that external loading of exosomes with cargo remains a significant challenge in developing exosomes as therapeutic tools.

The feasibility of the injection moulding (IM) was explored for the development of novel drug delivery systems. Controlled release formulations were developed using a substituted cellulose derivative, hydroxypropyl methyl cellulose acetate succinate (HPMCAS) and a graft co-polymer (Soluplus®). BCS class II drugs ibuprofen and the felodipine were selected based on their physicochemical properties. In the present work, a homogenous dispersion of drugs in the polymer matrices was achieved using Hot Melt Extrusion (HME) and extruded pellets obtained were used for the development of the injection moulded systems. Four systems were developed using the IM consisting of ibuprofen-HPMCAS, ibuprofen-Soluplus®, felodipine-PEO-HPMCAS and felodipine-Soluplus®. The ibuprofen acts as a good plasticiser compared to felodipine therefore, felodipine containing IM systems required a plasticiser (PEO) when processed with HPMCAS. The analysis of extruded pellets and injection moulded systems using modulated DSC (MDSC) and Raman spectroscopy confirmed the formation of an amorphous molecular dispersion (i.e solid solution) in the case of all four systems. The phase separation behaviour and the amorphous stability of the systems was studied at various stress conditions. This revealed the “surface crystallisation” behaviour of the ibuprofen-HPMCAS systems. Temperature-composition phase diagram constructed based on the melting point depression and the Flory-Huggins lattice solution theory provided the explanation for the phase separation and crystallisation behaviour of ibuprofen-HPMCAS systems. The advanced characterisation techniques like DMA, 2D XRD and 3D laser microscopy provided the detailed understanding of crystal habits, phase seperation and surface crystallisation. The significant effect of the stress conditions on the rate of shrinkage was observed where, higher shrinkage tendency of a HPMCAS IM system was observed compared to Soluplus® IM systems. The extruded pellets provided the faster drug release compared to the moulded tablets suggests the effect of particle size as well as the densification during IM on the dissolution rate of the dosage form. The nature of the polymer and processing history were the contributing factors for the dissolution of the dosage forms.
The thesis is hardbound in two volumes. Volume II starts at Chapter 5, page 135.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Ketoprofen is a nonsteroidal anti-inflammatory drug used for the treatment of mild to moderate pain in chronic inflammatory conditions. Due to its superior potency ketoprofen can be used in the treatment of inflammatory bowel disease (IBD). The treatment of IBD becomes safer and more effective when the drug is incorporated into colon-specific drug delivery systems. Pellets are multiparticulate solid dosage forms extensively investigated as colon-specific drug delivery systems. Pellets can be introduced into capsules or compressed into tablets. The industrial production of tablets containing pellets has several advantages when compared to the production of capsules. However, the compression of the pellets should not affect the release of the drug and the tablets should quickly disintegrate following administration. Therefore, the aim of this study was to develop tablets containing ketoprofen coated pellets for colon-specific drug release. For this, pellets were produced by extrusion and spheronization technique containing 40% (w / w) ketoprofen. Ketoprofen pellets obtained were coated with two different pH - dependent polymers derived from methacrylic acid (Opadry ® k 94 or Eudragit ® FS 30D) with weight gains of 10 or 20% (w / w). The coated pellets were then compressed under different pellets’ amounts and different compression forces. An extra- granular mixture of lactose and microcrystalline cellulose was used as compression aid. The in vitro release of ketoprofen from the systems obtained was evaluated in Bio Dis ® apparatus. The morphological and physical properties of pellets and tablets were assessed. The Eudragit ® FS 30 D coated pellets with weight gains of 10 or 20% showed higher efficiency of colon-specific delivery (94 %), however, the drug was released slowly and incompletely in conditions mimicking the pH of the colonic region. After compression of the pellets, the efficiency of colon – specific drug delivery was lowered after compression (between 20% and 61%, depending on the formulation). The lowest decrease of colon specific efficiency was observed in formulations containing lower amount of pellets, which also produced disintegrating matrices with potential for use in the topical treatment of IBD.
O cetoprofeno é um antiinflamatório não esteroidal usado para o tratamento de dores leves a moderadas, em condições inflamatórias crônicas. Devido a sua elevada potência antiinflamatória, o cetoprofeno pode ser aproveitado no tratamento das doenças inflamatórias intestinais (DII). O tratamento das DII se torna mais seguro e eficaz quando o fármaco é incorporado em sistemas de liberação cólon-específica. Pellets são formas farmacêuticas multiparticuladas bastante investigadas como sistemas de liberação cólon-específica. Após sua produção, os pellets podem ser inseridos em cápsulas ou comprimidos. A produção industrial de comprimidos contendo pellets apresenta inúmeras vantagens quando comparada ao processo de enchimento de cápsulas. No entanto, a compressão dos pellets não deve afetar as características de liberação do fármaco e os comprimidos formados devem se desintegrar rapidamente. Dessa forma, o objetivo deste trabalho foi desenvolver comprimidos contendo pellets revestidos para liberação cólon-específica de cetoprofeno. Para tanto, foram produzidos pellets contendo 40% (p/p) de cetoprofeno e celulose microcristalina pela técnica de extrusão e esferonização. Os pellets de cetoprofeno obtidos foram revestidos com dois diferentes polímeros pH-dependentes, ambos derivados do ácido metacrílico (Opadry ® 94 k ou Eudragit ® FS 30) com ganhos de massa 10 ou 20% (p/p). Os pellets revestidos foram então comprimidos com diferentes cargas de pellets e submetidos a diferentes forças de compressão, utilizando como adjuvante extra-pellets uma mistura granulada de lactose e celulose microcristalina. A liberação in vitro do cetoprofeno a partir das formas farmacêuticas obtidas foi avaliada em dissolutor Bio Dis aparato III. As caracterizações morfológicas e físicas dos pellets e comprimidos foram conduzidas. Os pellets obtidos por revestimento com Eudragit ® FS 30 D, com ganhos de massa de 10 ou 20%, mostraram elevada eficiência de liberação cólon-específica in vitro (até 94%), no entanto, o fármaco foi liberado de forma lenta e incompleta em meio com pH similar ao encontrado na região colônica. Após a compressão dos pellets, os valores de eficiência de liberação cólon-específica sofreram reduções entre 20% e 61%. A menor diminuição da eficiência de liberação cólon-específica foi observada nas formulações contendo a menor carga de pellets, as quais deram origem à matrizes desintegráveis com potencial para utilização no tratamento tópico das DII.

The feasibility of the injection moulding (IM) was explored for the development of novel drug delivery systems. Controlled release formulations were developed using a substituted cellulose derivative, hydroxypropyl methyl cellulose acetate succinate (HPMCAS) and a graft co-polymer (Soluplus®). BCS class II drugs ibuprofen and the felodipine were selected based on their physicochemical properties. In the present work, a homogenous dispersion of drugs in the polymer matrices was achieved using Hot Melt Extrusion (HME) and extruded pellets obtained were used for the development of the injection moulded systems. Four systems were developed using the IM consisting of ibuprofen-HPMCAS, ibuprofen-Soluplus®, felodipine-PEO-HPMCAS and felodipine-Soluplus®. The ibuprofen acts as a good plasticiser compared to felodipine therefore, felodipine containing IM systems required a plasticiser (PEO) when processed with HPMCAS. The analysis of extruded pellets and injection moulded systems using modulated DSC (MDSC) and Raman spectroscopy confirmed the formation of an amorphous molecular dispersion (i.e solid solution) in the case of all four systems. The phase separation behaviour and the amorphous stability of the systems was studied at various stress conditions. This revealed the “surface crystallisation” behaviour of the ibuprofen-HPMCAS systems. Temperature-composition phase diagram constructed based on the melting point depression and the Flory-Huggins lattice solution theory provided the explanation for the phase separation and crystallisation behaviour of ibuprofen-HPMCAS systems. The advanced characterisation techniques like DMA, 2D XRD and 3D laser microscopy provided the detailed understanding of crystal habits, phase seperation and surface crystallisation. The significant effect of the stress conditions on the rate of shrinkage was observed where, higher shrinkage tendency of a HPMCAS IM system was observed compared to Soluplus® IM systems. The extruded pellets provided the faster drug release compared to the moulded tablets suggests the effect of particle size as well as the densification during IM on the dissolution rate of the dosage form. The nature of the polymer and processing history were the contributing factors for the dissolution of the dosage forms.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
The morphology of extruded multiphase polymer systems is usually assessed through off-line characterization methods such as microscopy, which require much time for sample preparation and analysis of the results. This work aimed to the improvement of an optical detector to measure in real time the morphology of blends and polymeric composites in processing by extrusion, by laser light scattering at low angle (LALLS). Such equipment includes hardware and software and is based on measuring the intensity of light from a laser and is spread across and under the melt flow. The signals are collected by an array 91 of photodetectors sent to a computer, and displayed in real time on a three- dimensional plot of scattered light intensity to form a surface defined by 321 points. When analyzing the scattering profile valuable information can be determined that help to elucidate the morphology of the second phase particles. The LALLS detector was tested on bench using standard samples, which were prepared so that one of its parameters (orientation, second phase concentration, dispersed particle size or type of dispersed particle) were known. This allowed the systematic study of these samples and the detector device validation. Finally, the device was tested in real time on the extrusion process, and under different materials and operating conditions. Thus, the LALLS detector device created by the group was improved making it possible to evaluate in a practical way and in real time polymer blends in solid films and morphology of some blends and polymeric composites during extrusion.
A morfologia de sistemas poliméricos polifásicos é usualmente avaliada através de métodos de caracterização off-line, tal como a microscopia, os quais demandam muito tempo para a preparação das amostras e para a análise dos resultados. Este trabalho teve como principal objetivo o aperfeiçoamento de um detector óptico para medida em tempo real da morfologia de misturas e compostos poliméricos no processamento por extrusão, através do espalhamento de luz laser em baixo ângulo (LALLS). Tal equipamento inclui hardware e software e baseia-se na medida da intensidade da luz que provém de um laser e que é espalhada através do material fundido e sob fluxo. Os sinais são coletados por um arranjo de 91 fotodetectores, enviados a um computador, e apresentados em tempo real num gráfico tridimensional da intensidade de luz espalhada formando uma superfície definida por 321 pontos. Ao se analisar o perfil de espalhamento tem-se valiosas informações que ajudam elucidar a morfologia das partículas de segunda fase presentes. O detector de LALLS foi testado em bancada com o uso de amostras-padrão, as quais foram elaboradas de maneira que um de seus parâmetros (orientação, concentração de segunda fase, tamanho de partícula dispersa ou tipo de partícula dispersa) tivesse sido alterado de forma conhecida. Isso permitiu o estudo sistematizado dessas amostras e a validação do dispositivo detector. Por fim, o dispositivo foi testado em tempo real no processo de extrusão, sob diferentes condições materiais e de operação. Com isso, o dispositivo detector de LALLS criado pelo grupo foi aperfeiçoado possibilitando avaliar-se de forma prática e em tempo real: a morfologia de misturas poliméricas na forma de filmes sólidos e algumas misturas e compostos poliméricos durante a extrusão.

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A medida da Distribuição do Tempo de Residência (DTR) em tempo real durante o processo de extrusão permite realizar uma análise global do desempenho do equipamento (extrusora), proporcionando um melhor conhecimento do comportamento do fluxo do material durante todo o processo. Neste trabalho foi desenvolvido um sistema ótico (hardware e software) para detecção de curvas DTR em tempo real durante a extrusão de polímeros. O sistema de detecção teve sua eficiência validada. Os resultados obtidos sugeriram que o sistema foi capaz de detectar as curvas de DTR com um elevado número de pontos, bem como se mostrou sensível a variação na concentração e no tipo de traçador utilizado; além disso, foi possível confirmar a boa reprodutibilidade das medições o que qualificou o sistema para o levantamento das curvas de DTR em tempo real. Posteriormente, foram avaliados os efeitos nas alterações das variáveis de processamento sobre a forma e os parâmetros das curvas de DTR. Foi possível confirmar que a variação na taxa de alimentação possui uma maior influência sobre as curvas DTR do que a velocidade da rosca, fato este corroborado com a literatura. também constatou-se que as alterações no Índice de Fluidez do material de fluxo afetaram a dispersão (capacidade de mistura) nas curvas de DTR. A eficiência energética do processo de extrusão também foi analisada através do levantamento da energia mecânica dissipada e da energia mecânica especifica, foi apresentada uma correlação destes parâmetros energéticos com o tempo de residencia médio. Neste trabalho também foi utilizado uma ferramenta computacional (WinTXS™) para simular as condições de processamento experimentais; a partir daí realizou-se a comparação entre os dados medidos experimentalmente e os simulados, de modo a estabelecer um grau de concordância entre os mesmos. Os resultados obtidos permitiram comprovar que medição da DTR e a simulação computacional unidimensinal são ferramentas importantes no estudo do processo de extrusão de polímeros.
The measurement of Residence Time Distribution (RTD) in real time during the extrusion process allows a comprehensive analysis of equipment performance (extruder), providing a better understanding of the material flow behavior throughout the process. This work developed an optical system (hardware and software) to detect RTD curves in real time during the extrusion of polymers. The efficiency in the detection system was validated. The results obtained suggest that the system it was able to detect the RTD curves with a large number of points, and is sensitive to variations in the concentration and type of tracer used; furthermore, it was possible to confirm the good reproducibility of the measurements which qualify the system for lifting the RTD curves in real time. subsequently, we evaluated the effects of changes in processing variables on the form and parameters of the RTD curves. It was confirmed that the variation in feed rate has a larger influence on cornering RTD than the speed of the screw, a fact corroborated by the literature. It was also found that the change in Melt Index affect the flow of material dispersion (mixing capacity) in the RTD curves. The energy efficiency of the extrusion process was also analyzed by surveying the dissipated mechanical energy and mechanical energy specifies a correlation is presented these energy parameters with the average residence time. This work also used a computational tool (WinTXS ™) to simulate the processing conditions; there after it conducted a comparison between the experimentally measured and simulated data to establish the degree of agreement there between. Results show evidence that measurement of RTD and unidimensinal computer simulation is important tools in the study of polymer extrusion process.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.
Includes bibliographical references (leaves 138-140).
This thesis deals with analytical and experimental work performed on the extrusion of microcellular plastics with cell sizes of 20 microns or less and cell densities of about a billion cells per cm3. An analytical model of cell nucleation and cell growth during extrusion was developed. This model predicts the nucleation rate by taking into account Gibbs free energy change due to phase separation, as well as surface energy, in binary systems (such as polymer/gas mixtures). The cell growth kinetics during extrusion is also studied under some limiting cases. The analysis shows that due to the simultaneous occurrence of cell nucleation and cell growth during extrusion, these two phenomena are coupled and compete with each other for the gas dissolved in the polymer. With the aid of this model the important extrusion parameters affecting the microstructure of the foam were identified. An order-of-magnitude prediction of cell size, cell density and foam void fraction were made based on realistic numerical values of these parameters. The next phase of the project consisted of using the analytical model and Axiomatic Design Theory to design a tandem extrusion system for wire coating. Satisfaction of the Independence Axiom showed that the process was controllable. Preliminary analysis of the Information Axiom indicated that the system would be stable. Experiments were performed over a range of conditions to determine their effects on the final wire insulation diameter and capacitance. The experimental results were compared to the analytical predictions to further verify the validity of the model as well as to determine its limitations.
by Yoddhojit Sanyal.
Sc.D.

L'oxydation des lipides entraine la formation de radicaux libres, toxiques et de nombreux produits responsables du gout rance. Afin de retarder cette oxydation, des antioxydants de synthese ou d'origine naturelle sont employes par les industries alimentaires et cosmetiques. Au cours de ce travail, nous avons utilise le 2,2-diphenyl-1-picrylhydrazyle (dpph_) pour evaluer l'activite antiradicalaire des antioxydants en milieu methanolique, a temperature ambiante. Le pouvoir antiradicalaire (par) a ete compare au pouvoir antioxydant (pao) determine par l'autooxydation acceleree du linoleate de methyle en milieu apolaire a 110c. Dans une deuxieme partie, nous avons etudie le comportement de quelques antioxydants dans un systeme complexe alimentaire obtenu par cuisson-extrusion. Les activites antiradicalaires de composes phenoliques et d'extraits vegetaux ont ete mesurees. Trois types de comportement ont ete differencies: les reactions lentes, intermediaires, et rapides. Une etude cinetique de deux reactions lentes (bht et eugenol) et d'une reaction rapide (isoeugenol) a permis de determiner des ordres globaux et des constantes de vitesses. Des mecanismes reactionnels sont proposes. Une comparaison des valeurs par et pao montre des similitudes mais egalement quelques differences de classement importantes, notamment pour l'acide ascorbique, l'acide isoascorbique et quelques methoxy phenols. Deux etudes en cuisson-extrusion ont ete effectuees. Les extrudats contenant de l'huile de tournesol et des tocopherols endogenes, ont montre une oxydation faible (20%) apres une annee de conservation a temperature ambiante et l'addition d'antioxydants exogenes est donc restee sans effet. Dans un deuxieme essai a base de graisse de poule, une bonne protection a 40c a ete observee avec un extrait de romarin riche en acide carnosique et le bht

Mise en evidence d'une pompe a protons de type redox localise au niveau de la membrane plasmique. Etude de son fonctionnement dans les conditions physiologiques et relation avec la pompe atpase. Controle du processus d'excretion de metabolites par la modulation du ph extracellulaire

Extrusion blow molding is the process of choice for the production of many hollow products. Parison formation is the most critical stage in the process, as the dimensions of the blow-molded part are directly related to the dimensions of the parison.
In this work, a 'soft sensor' for cycle-to-cycle control of parison length is developed. A model for parison swell is proposed where the parameters of the model can be tuned from cycle to cycle to match the experimental parison dimensions. The technique was tested on a real intermittent extrusion blow molding machine where a target parison length was achieved by either adjusting the flow rate of the polymer or the die gap opening.
In this work, we have also proposed a technique for estimation of the average relaxation time using a combination of Carreau and Maxwell models. This technique is based on the observed time for parison swell outside the die, and it finds a relaxation time that closely represents the polydisperse nature of blow molding grade resins. The technique could be extended to estimate multiple relaxation times using a generalized Maxwell model. (Abstract shortened by UMI.)

L'amélioration de la dissolution des médicaments peu solubles présente de nombreux défis.Dans cette thèse, un procédé d'extrusion-sphéronisation a été étudié en profondeur pour améliorer la dissolubilité du médicament avec une formulation de nano-émulsion. Le but du travail de thèse est de décrire les propriétés et les procédés de fabrication de minigranules permettant d'augmenter la solubilité des principes actifs peu solubles dans l'eau et donc d‘améliorer leur biodisponibilité lors de l'administration par voie orale, pour deux modèles de molécules différentes qui sont l‘acide folique (vitamine peu soluble dans l'eau) et le kétoprofène (anti-inflammatoire non stéroïdien qui présente une solubilité limitée dans les fluides gastriques à cause de son pKa (classe II dans le système de classification biopharmaceutique – BCS, ayant une action anti-inflammatoire, antalgique et antipyrétique). Cette étude décrit la préparation par extrusion-sphéronisation, caractérisation et étude de dissolution in vitro d'acide folique et de pastilles de kétoprofène revêtues de Acryl-EZE®, Advantia® Performance dans un minicoatère à lit fluidisé. Les résultats des essais ont montré la faisabilité de la préparation de pastilles enrobées entériques contenant un AINS et que, en revêtant le système multiparticulaire avec Acryl-EZE® 93A92545 et Advantia® Performance190024HA49 à un gain pondéral de 17,5%, 12,0%, respectivement, du médicament à partir des pastilles peuvent être obtenus. Les résultats des essais de dissolution ont indiqué que dans un milieu acide, le revêtement de film a entraîné un retard dans la libération du médicament, alors qu'aucun retard n'a été observé dans un milieu tampon à pH 6,8
Improvement in dissolution of poorly soluble drugs has many challenges.In this thesis, an extrusion-spheronization process was thoroughly studied forimproving dissolubility of drug with nano-emulsion formulation.The aim of the thesis work is to describe the properties and manufacturing processes ofpellets to increase the solubility of poorly soluble active ingredients in water and thus improvetheir bioavailability when administered orally: folic acid (water-insoluble vitamin) andketoprofen (Non-steroidal anti-inflammatory, having anti-inflammatory, analgesic andantipyretic action, class II in the Biopharmaceutical Classification System).This study describes the preparation by extrusion-spheronization, characterisation andin vitro dissolution study of folic acid and ketoprofen pellets. Ketoprofen pellets coated withAcryl-EZE®, Advantia® Performance in a fluid-bed minicoater. The results of the tests showedthe feasibility of the preparation of enteric-coated pellets containing a NSAID and that bycoating the multiparticulate system with either 17.5% Acryl-EZE® 93A92545 or with 12%Advantia® Performance 190024HA49 weight gain, an enteric release of the drug from thepellets can be obtained. The results of dissolution testing indicated that in acidic media, entericfilm coating resulted in a delay in the release of the drug, while no delay was observed in pH6.8 buffer media

Supercapacitors, also known as electrochemical capacitors, have shown great potential as energy storage devices; and 3D printing likewise as a manufacturing technique. This research progressively investigates combining these two technologies to fabricate 3D-printed, electrochemical double-layer capacitors (EDLCs). Small EDLCs were designed in a sandwich structure with an FDM-printed plastic frame and carbon electrodes. Inkjet printing was initially combined with FDM printing to produce a pilot sample with a silver ink current collector, however this performed poorly (Cs = 6 mF/g). Henceforth a paste extrusion system was added to the FDM printer to deposit the current collectors and electrodes, fabricating the entire device in a single continuous process. This process was progressively developed and tested, ultimately attaining specific capacitances of 200 mF/g. The fully integrated 3D printing process used to manufacture the EDLCs was a novel approach. Combining the FDM printer with a paste extruder allowed for a high degree of dimensional accuracy, as well as simplifying the production process. This aspect of the design functioned successfully, without significant faults, and proved a reliable fabrication method. The later designs used in this study provided the EDLCs extendable by incorporating connection jacks. This was to create the possibility to increase capacitance simply by connecting multiple EDLCs together. Tests of this feature showed that it worked well, with the extendable EDLCs delivering outputs very close to the theoretical maximum efficiency of the unit. Carbon conductive paint was applied as a current collector and electrode for the 3D printed EDLCs in an exploration of metal-free 3D printed supercapacitors. These metal-free EDLCs were found to provide around 60% of the specific capacitance of the best performing EDLC variant produced (silver paint current collectors with activated carbon and carbon paint mixture electrodes). Although considerable improvement is required to produce EDLC samples with comparable capacitances to existing commercial manufacturing techniques, this study lays important groundwork in this area, and has introduces effective and innovative design ideas for supercapacitors and integrated 3D printing processes.

Orientadores: Mario Fernando de Goes, Luis Roberto Marcondes Martins
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-03T15:59:52Z (GMT). No. of bitstreams: 1 Cordeiro_NaraPereirad'Abreu_D.pdf: 3561839 bytes, checksum: 125cbc91719d6a902ce59502debf7873 (MD5) Previous issue date: 2003
Resumo: o objetivo deste estudo foi avaliar a resistência ao cisalhamento por extrusão (push out) entre a dentina intra-radicular e pinos de fibra de vidro nas regiões cervical, média e apical de raízes utilizando dois sistemas de cimentação adesiva. Foram selecionados vinte pré-molares inferiores unirradiculares recém extraídos por motivos ortodônticos, hígidos e livres de trincas. As coroas dos dentes foram removidas na altura da junção cemento esmalte. As polpas dentais foram removidas através de limas endodônticas e os condutos radiculares foram preparados com brocas de largo nO 5, com 8,Omm de penetração. As raízes foram divididas em dois grupos de 10: Grupo 1- pino fixados com o sistema adesivo autocondicionante ED Primer e cimento resinoso Panavia F; Grupo 2- pinos fixados com o sistema adesivo de frasco único Single Bond e cimento resinoso Rely X. Após a fixação dos pinos, as raízes foram mantidas em estufa a 37°C, por 24 h. A porção mais apical das raízes foi seccionada até a altura em que a raiz apresentasse 8,Omm de comprimento. Em seguida, as raízes foram seccionadas transversalmente e 3 discos de 2,7mm de altura foram obtidas e classificadas segundo a região cervical, média e apical do pino. O ensaio de resistência de união por extrusão foi realizado em máquina de ensaio universal Instron 4411 onde uma haste metálica com ponta ativa de 1,Omm de diâmetro produziu a carga para efetuar o deslocamento do pino do conduto radicular. Os valores médios de resistência de união por extrusão não apresentaram diferenças estatísticas significantes no terço cervical da raiz entre os dois materiais de fixação avaliados. Nas regiões média e apical do conduto, os valores de resistência de união apresentados pelo Sing/e Bond + Re/y X foram superiores e estatisticamente diferentes em relação aos valores apresentados pelo sistema ED Primer + Panavia F (p< 0,05). Para os dois materiais em estudo, não houve diferença estatística quando comparadas as regiões média e cervical do pino, porém apresentaram diferença estatística em relação à região apical (p< 0,05). Após o ensaio de cisalhamento por extrusão, os espécimes foram seccionados no sentido longitudinal para análise em microscopia eletrônica de varredura. A zona de interdifusão adesivo/dentina produzida pelo adesivo de frasco único Sing/e Bond apresentou-se mais espessa do que a zona de interdifusão apresentada pelo adesivo autocondicionante ED Primer. Houve áreas desmineralizadas com presença de túbulos dentinários abertos porém parcialmente preenchidos pela resina em ambos os grupos. Também foram observadas bolhas que variaram de tamanho e forma na camada de cimento junto à área da interface de união e mais constantes no terço apical das raízes. Palavras-chave: pino de fibra de vidro; cimento resinoso; sistema adesivo; resistência de união; "push out
Abstract: The purpose of this study was to evaluate the bond strength between fiber posts cemented in root dentin considering different depths of the roots (cervical, median and apical) and two luting materiais, through push out tests and to examine the integration among these components through scanning electron microscopy. Twenty sound bicuspids, tree trom cracks, extracted for orthodontic reasons, were selected. The crowns were removed at the cement enamel junction. The pulps were removed with endodontic reamers and the first 8,Omm of the canais were shaped with number 5 largo burs. The roots were divided into two groups of 10 each. The roots trom group 1 received fiber posts cemented with the self etching primer ED Primer and the composite resin Panavia F., while the roots of Group 2 received fiber posts cemented with the one bottle adhesive Single Bond and the composite resin Rely X. After the posts cementation, the roots were kept in humidity at 3-,0 C for 24 hours. The most apical part of the roots were sectioned until they were 8.0mm long. After that, the roots were sectioned transversally and three 2.7mm thick sections were obtained: cervical, median and apical. The push out test that evaluated bond strength between luting material and root dentin was carried out on an Instron (4411) testing machine. The specimens were positioned on a steel support platform with the post centered over a 2.0mm hole in the platform. A steel probe 1.0mm in diameter was centered over the post and used to apply force to the test specimens. Data from the push out test revealed no statistically significant differences at the cervical portion of the root between the two cementation systems tested. At the median and apical portion of the root, the bond strength values presented by the Sing/e Bond and Re/y X were superior and statistically different from those presented by ED Primer and Panavia F (PDoutorado
Dentística
Doutor em Clínica Odontológica

Following the discovery of the one-dimensional sequence of human DNA, much focus has been directed on microscopy and molecular techniques to learn about the spatial organization of chromatin in a 3D cell. The development of these powerful tools has enabled high-resolution, genome-wide analysis of chromosome structure under many different conditions. In this thesis, I focus on how the organization of interphase chromatin is established and maintained following mitosis. Mitotic chromosomes are folded into helical loop arrays creating short and condensed chromosomes, while interphase chromosomes are decondensed and folded into a number of structures at different length scales ranging from loops between CTCF sites, enhancers and promoters to topologically associating domains (TADs), and larger compartments. While the chromatin organization at these two very different states is well defined, the transition from a mitotic to interphase chromatin state is not well understood. The aim of this thesis is to determine how interphase chromatin is organized following mitotic chromosome decondensation and to interrogate factors potentially responsible for driving the transition. First, I determine the temporal order with which CTCF-loops, TADs, and compartments reform as cells exit mitosis, revealing a unique structure at the anaphase-telophase transition never observed before. Second, I test the role of transcription in reformation of 3D chromosome structure and show that active transcription is not required for the formation of most interphase chromatin features; instead, I propose that transcription relies on the proper formation of these structures. Finally, I show that RNA in the interphase nucleus can be degraded with only slight consequences on the overall chromatin organization, suggesting that once interphase chromatin structures are achieved, the structures are stable and RNA is only required to reduce the mixing of active and inactive compartments. Together, these studies further our understanding of how interphase structures form, how these structures relate to functional activities of the interphase cell, and the stability of chromatin structures over time.

[EN] In the present Doctoral Thesis, antimicrobial active packaging materials, at lab and at semi-industrial scale, have been developed with the aim to reduce the natural flora of peeled and cut fruit and extend its shelf life. Packaging prototypes have been developed for their further application. Prior to developing the active materials, the most suitable active agents were selected. To that end, the antimicrobial properties of the volatile active agents citral, hexanal and linalool and mixtures thereof were evaluated against typical microorganisms related to fruit spoilage, molds and yeast, concluding that the effectiveness of the mixture is higher than the sum of the effectiveness of the individual agents. Likewise, non-volatile antimicrobial agents such as potassium sorbate and sodium benzoate were selected, which are widely used in the food industry due to their antifungal properties. With the selected active agents, monolayer polypropylene (PP) films with different concentration of the active mixture citral, hexanal and linalool, at lab scale by means of extrusion, and bilayer films at semi-industrial scale with different active layer thickness by means of coextrusion were prepared. Besides, active packaging trays were developed at semi-industrial scale by thermoforming active sheets obtained by coextrusion of PP and ethyl vinyl acetate (EVA) compounds containing potassium sorbate and sodium benzoate as active agents. Mechanical, barrier and thermal properties of the developed active packaging materials, as well as their sealability and transparency were evaluated. In general, the materials' properties were not affected in a significant manner. However, active trays decreased in transparency due to the incorporation of non-volatile active agents. The release kinetics of the volatile and non-volatile active agents were studied at different temperatures, defining their diffusion coefficients by the adjustment to mathematic models based on Second's Law Fick. Among the volatile active agents, hexanal showed a higher diffusion coefficient, followed by citral and linalool. On the other hand, very small differences were observed between potassium sorbate and sodium benzoate diffusion coefficients, being of the same order of magnitude. In vitro tests were also performed at different temperatures to evaluate the antimicrobial properties of the developed materials. In general, the active packaging materials showed high antimicrobial properties which were enhanced with the increment of temperature. Once the properties of the developed materials were evaluated, in vivo tests with peeled and cut orange and pineapple were performed by packing these fruits with the active film, active tray and their combination (active packaging system). In general, the active packaging system improved the microbiological preservation of the fruit for longer times, between 2 and 7 days for orange and pineapple, respectively, and maintained quality parameters of the fruit at stable levels for longer times. Lastly, the safety of the active packaging materials was evaluated according to the European food contact materials and food legislation, and it was concluded that these materials were not of any safety concern for the consumers.
[ES] En la presente Tesis Doctoral se han desarrollado materiales de envase activo antimicrobiano, a escala laboratorio y a escala semi-industrial, con el objetivo de reducir la proliferación de la flora natural de la fruta pelada y cortada y extender su vida útil. Se han desarrollo distintos prototipos para su posterior aplicación industrial Previo al desarrollo de los materiales de envase, se ha realizado una selección de agentes activos más idóneos. Para ello se han estudiado mediante ensayos in vitro las propiedades antimicrobianas de agentes activos volátiles, citral, hexanal y linalool y diferentes mezclas de los mismos, frente a distintos microorganismos típicos del deterioro de las frutas, mohos y levaduras, concluyendo que la efectividad de la mezcla de los tres es superior a la suma de la efectividad de los activos de forma individual. Así mismo, también se han seleccionado antimicrobianos no volátiles como el sorbato potásico y benzoato sódico, los cuáles son ampliamente empleados en la industria alimentaria debido principalmente a sus propiedades antifúngicas. Con los agentes activos seleccionados, se han desarrollado películas monocapa de polipropileno (PP) con distintas concentraciones de la mezcla activa, citral, hexanal y linalool, a escala laboratorio, mediante técnicas de extrusión, y películas bicapa a escala semi-industrial con distintos espesores de capa activa mediante coextrusión. Por otra parte, se desarrollaron bandejas activas a escala semi-industrial mediante termoconformado de láminas obtenidas por coextrusión de compuestos de PP y etilvinilaceteto (EVA) con sorbato potásico o benzoato sódico como agentes antimicrobianos. Se han evaluado las propiedades mecánicas, barrera y térmicas de los materiales activos desarrollados, así como su sellabilidad y transparencia. En general, las propiedades de los polímeros no se vieron afectadas de manera relevante. Sin embargo, las bandejas activas perdieron su carácter transparente debido a la incorporación de los agentes activos no volátiles. Se ha estudiado la cinética de liberación de los compuestos activos volátiles y no volátiles a distintas temperaturas, determinando los coeficientes de difusión de los agentes activos mediante el ajuste a modelos matemáticos de difusión basados en la Segunda Ley de Fick. Entre los agentes volátiles, el hexanal mostró un mayor coeficiente de difusión seguido de citral y linalool. Por otra parte, no hubo apenas diferencia en los coeficientes de difusión del sorbato potásico y benzoato sódico, siendo éstos del mismo orden de magnitud. Igualmente, se han realizado diferentes experimentos in vitro a distintas temperaturas para determinar las propiedades antimicrobianas de los materiales desarrollados. En general, los materiales activos presentan una elevada capacidad antimicrobiana que se ve potenciada al aumentar la temperatura de exposición. Una vez evaluadas las características de los materiales desarrollados, se han efectuado ensayos de envasado de naranja y piña pelada y cortada con las películas y las bandejas activas y con la combinación del sistema de envase bandeja activa termosellada con la película activa. En general, el sistema de envase activo mejoró la conservación de la fruta por un mayor tiempo, entre 2 y 7 días para la naranja y piña, respectivamente, presentando una gran capacidad antimicrobiana y manteniendo los parámetros de calidad de la fruta en niveles estables por un mayor tiempo. Por último, se ha estudiado la seguridad de estos materiales de acuerdo a la legislación de materiales en contacto con alimentos y la legislación alimentaria europea, concluyendo que los materiales activos desarrollados no presentan preocupación para la seguridad de los consumidores.
[CAT] En la present Tesi Doctoral s'han desenvolupat materials d'envasament actiu antimicrobià, a escala de laboratori i a escala semi-industrial amb l'objectiu de reduir la proliferació de la flora natural de la fruita pelada i tallada i estendre la seua vida útil. S'han desenvolupament diferents prototips per a la seua posterior aplicació industrial. Previ al desenvolupament dels materials actius, s'han seleccionat els agents actius mes idonis estudiant mitjançant assajos in vitro les propietats antimicrobianes d'agents actius volàtils, citral, hexanal i linalool i diferents mescles dels mateixos, enfront de diferents microorganismes típics de la deterioració de les fruites -floridures i llevats- concloent que l'efectivitat de la mescla dels tres és superior a la suma de l'efectivitat dels actius de forma individual. Així mateix, s'han seleccionat antimicrobians no volàtils, sorbat potàssic i benzoat sòdic, els quals son àmpliament empleats a l'industria alimentaria per les seues propietats antifúngiques. Amb els agents actius seleccionats, s'han desenvolupat pel·lícules monocapa de polipropilè (PP) amb diferents concentracions de la mescla activa, citral, hexanal i linalool, a escala laboratori, mitjançant tècniques d'extrusió, i pel·lícules bicapa a escala semi-industrial amb diferents espessors de capa activa mitjançant coextrusió. D'altra banda, s'han desenvolupat safates actives a escala semi-industrial mitjançant termoconformació de làmines obtingudes per coextrusió de compostos de PP i etil vinil acetat (EVA) amb sorbat potàssic o benzoat sòdic com a agents antimicrobians. S'han avaluat les propietats mecàniques, barrera i tèrmiques dels materials actius desenvolupats, així com la seua sellabilidad i transparència. En general, les propietats dels polímers no es van veure afectades de manera rellevant. No obstant això, les safates actives van perdre el seu caràcter transparent a causa de la incorporació dels agents actius no volàtils. S'ha estudiat la cinètica d'alliberament dels compostos actius volàtils i no volàtils a diferents temperatures, determinant els coeficients de difusió dels agents actius mitjançant l'ajust a models matemàtics de difusió basats en la Segona Llei de Fick. Entre els agents volàtils, l' hexanal va mostrar un major coeficient de difusió seguit de citral i linalool. D'altra banda, no va haver-hi a penes diferències en els coeficients de difusió del sorbat potàssic i benzoat sòdic, sent aquests del mateix ordre de magnitud. Igualment, s'han realitzat diferents experiments in vitro a diferents temperatures per determinar les propietats antimicrobianes dels materials desenvolupats. En general, els materials actius presenten una elevada capacitat antimicrobiana que es veu potenciada en augmentar la temperatura d'exposició. Una vegada avaluades les característiques dels materials desenvolupats s'han efectuat assajos d'envasament de taronja i pinya pelada i tallada amb la safata, la pel·lícula activa i la seva combinació (sistema d'envàs actiu). En general, el sistema d'envàs actiu va millorar la conservació de la fruita per un major temps, entre 2 i 7 dies per a la taronja i pinya respectivament, presentant una gran capacitat antimicrobiana i mantenint els paràmetres de qualitat de la fruita en nivells estables per un major temps. Finalment, s'ha estudiat la seguretat d'aquests materials d'acord a la legislació de materials en contacte amb aliments i la legislació alimentària europea, concloent que els materials actius desenvolupats no presenten preocupació per a la seguretat dels consumidors.
Lara Lledó, MI. (2016). Antimicrobial packaging system for minimally processed fruit [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/61388
TESIS
Premiado

Sistemas monolíticos particulados contendo os constituintes ativos veiculados na forma de grânulos revestidos - pellets - têm recebido crescente atenção nos últimos anos, em função da otimização na biodisponibilidade e segurança na liberação do fármaco. A utilização destas unidades, como componentes de comprimidos traz, como principal vantagem, a divisibilidade da forma sem a perda do perfil biofarmacêutico desejado para o fármaco. Para sua produção, é indispensável a manutenção da integridade do revestimento daquelas unidades. Uma estratégia para o alcance deste objetivo envolve a utilização de grânulos inertes deformantes, comprimidos em conjunto com os grânulos revestidos, que atuam como um sistema de amortecimento das forças de compressão. Neste trabalho investigou-se a produção de grânulos deformantes através de dois métodos de granulação por via úmida, avaliando a influência de adjuvantes sobre as características dos produtos obtidos. Empregando a técnica de extrusão/esferonização obtiveram-se grânulos com propriedades de fluxo, empacotamento e resistência mecânica aceitáveis. O efeito dos adjuvantes sobre as etapas tecnológicas foi estudado por meio de um planejamento fatorial. Testaram-se duas variedades de celulose microcristalina, os desintegrantes croscarmelose sódica e crospovidona e soluções aglutinantes aquosas e hidroetanólicas de povidona. Para o desenvolvimento dos comprimidos utilizaram-se, como modelo, grânulos revestidos gastro-resistentes contendo omeprazol. A influência da composição dos grânulos deformantes sobre a liodisponibilidade do fármaco dos comprimidos foi avaliada através de análise fatorial 23. Os grânulos deformantes protegeram o revestimento polimérico dos pellets com diferentes intensidades.
Monolythic particulate systems containing the active constituents as coated pellets became great interest due to the improvement of safety and bioavailability. The use of such units as components of tablets shows as main advantages the divisibility of the pharmaceutical dosage form without loosing the desired biopharmaceutical profile of the drug. Consequently for the tablet production, the integrity of the polymeric film must be attained. A strategic option involves the utilization of inert soft pellets, which could be compressed together with the film coated pellets, absorbing the compaction forces. In this work the production of soft pellets was investigated using two wet granulation methods and evaluating the influence of formulation adjuvants on the pellets properties. The extrusion/spheronization technique yielded pellets with acceptable flow, packing and mechanical characteristics. The influence of the adjuvants on the technological steps was carried out through a statistical designed experiment. Microcrystalline cellulose from two producers, the disintegrants sodium croscarmellose and crospovidone, and aqueous and hydroethanolic dispersions of povidone, as binder, were tested. For the tablets development omeprazol gastroresistant film coated pellets were used as model. Aiming at the study of the influence of the soft pellets composition on drug lyoavailability was performed a 23 factorial experiment. The soft pellets protected at different intensities the polymeric coating of the gastroresistant pellets.

Роботу виконано на кафедрі ком’пютерно-інтегрованих технологій Тернопільського національного технічного університету імені Івана Пулюя Міністерства освіти і науки України Захист відбудеться 24 грудня 2019 р. о 12 .30 годині на засіданні екзаменаційної комісії № 45 у Тернопільському національному технічному університеті імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул.Руська, 56, навчальний корпус №1, ауд. 401
Р.В. Ковбасюк, А.А. Луциків. Розробка та дослідження автоматизованої системи керування технологічним процесом виробництва металополімерних труб. 151 – автоматизація та комп’ютерно-інтегровані технології. – Тернопільський національний технічний університет імені Івана Пулюя. – Тернопіль, 2019. В магістерській роботі розглянуто процес виготовлення пластикових труб. Було проаналізовано основні аспекти технологічного процесу, визначено найбільш важливі параметри, які суттєво впливають на виробництво труб. Розроблено автоматизовану систему керування процесом екструзії для виробництва полімерних труб. R.V. Kovbasyuk, A.A. Lutsykiv. Development and research of an automated control system for technological process of production of metal-polymer tubes. 151 - Аutomation and computer integrated technologies. - Ivan Puliuyi Ternopil National Technical University. - Ternopil, 2019. In the master's work the process of manufacturing of plastic pipes is considered. The basic aspects of the technological process were analyzed, the most important parameters that significantly influence the production of pipes were identified. An automated control system for extrusion process for the production of polymer tubes has been developed.
ВСТУП 7 1. АНАЛІТИЧНА ЧАСТИНА 8 1.1. Пластмасові труби: область застосування 8 1.2. Переваги і недоліки металопластикових труб 9 1.3. Матеріали для виробництва труб 11 1.4 Наповнювачі, пластифікатори, стабілізатори та інші добавки для виробництва пластмаси 13 2 ТЕХНОЛОГІЧНА ЧАСТИНА 18 2.1. Основні аспекти виробництва полімерних труб 18 2.2. Процес екструзії труб 19 2.3. Процес екструзії загалом 20 2.3.1 Одно шнекове екструдування. 22 2.3.2 Двохвинтові екструзії 26 2.4 Лінія екструзії труб 29 2.4.1 Пластина штифта, оправка та дивавлювана головка. 30 2.4.2 Калібрування та охолодження 32 2.2.3 Знімач і фреза 34 2.2.4 Додаткове обладнання 35 3 КОНСТРУКТОРСЬКА ЧАСТИНА 37 3.1 Загальні аспекти функціонування системи 37 3.2 Цілі системи 38 3.3 Призначення та склад лінії екструзії 38 3.4 Критерій якості створеної системи 40 3.5 Обгрунтування системи контролю 42 3.6 Обгрунтування та створення структурної схеми 43 3.7 Комплекс технічних засобів 47 3.7.1 Обладнання нижнього (польового) рівня 47 3.7.2 Обладнання верхнього (диспетчерського) рівня 50 3.8 Функціональна схема автоматизації 50 3.9 Розробка інформаційних потоків 54 4 НАУКОВО-ДОСЛІДНА ЧАСТИНА 63 4.1. Алгоритм автоматичного регулювання 63 5. СПЕЦІАЛЬНА ЧАСТИНА 70 5.1 Оспис середовища розробки системи СКАДА. 70 6. ОБГРУНТУВАННЯ-ЕКОНОМІЧНОЇ ЕФЕКТИВНОСТІ 77 6.1. Розрахунок норм часу на виконання науково-дослідної роботи 77 6.2 Визначення витрат на оплату праці та відрахувань на соціальні заходи 78 6.3 Розрахунок матеріальних витрат 81 6.4 Розрахунок витрат на електроенергію 82 6.5 Розрахунок суми амортизаційних відрахувань 83 5.6 Обчислення накладних витрат 84 5.7 Складання кошторису витрат та визначення собівартості науково-дослідницької роботи 85 5.8 Розрахунок ціни розробки системи 86 5.9 Визначення економічної ефективності і терміну окупності капітальних вкладень 87 7 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 89 7.1 Організація охорони праці при роботі з системою управління 89 7.2 Електробезпека 91 7.3 Розрахунок заземлення 94 8 ЕКОЛОГІЯ 98 8.1 Екологізація виробництва 98 8.2 Зниження енергоємності та енергозбереження. 99 8.3 Джерела електромагнітних полів, іонізуючого випромінення та методи їх знешкодження. 101 ОСНОВНІ ВИСНОВКИ ДИПЛОМНОЇ РОБОТИ 103 БІБЛІОГРАФІЯ 104

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária
Introdução: A Endodontia constitui uma ciência integrada no conjunto das ciências da saúde. O tratamento endodôntico não cirúrgico divide-se em três grandes fases: Acesso endodôntico, preparação biomecânica e obturação dos canais radiculares. A obturação consiste na etapa final do tratamento endodôntico não cirúrgico oferecendo condições de regeneração aos tecidos perirradiculares. Objetivo: O objetivo deste trabalho é realçar a importância da obturação do sistemas de canais radiculares, apresentar algumas técnicas usadas e avaliar os efeitos nos tecidos periodontais da variação da temperatura e extrusão apical associada às técnicas de obturação termoplásticas. Materiais e Métodos: Para a realização deste trabalho foi efetuada uma pesquisa bibliográfica nas bibliotecas da Universidade Fernando Pessoa e Faculdade de Medicina Dentária da Universidade do Porto e nos motores de busca Pubmed, SciencDirect, SciElO, Google Académico, B-on. As palavras-chaves utilizadas foram: Temperature changes in obturation, temperature damages in obturation, filling gutta-percha extrusion, gutta-percha overfiling, warm obturation, leakage and endodontics, filling and endodontics, System B, Termoplastic. A pesquisa foi limitada a artigos de revisão em Inglês, Espanhol e Português, publicados desde o ano 1999 até ao ano de 2013. Desenvolvimento: As técnicas termoplásticas favorecem a obturação tridimensional dos sistemas de canais radiculares, sendo frequente a obturação de ramificações laterais e deltas apicais. Estas novas técnicas têm a vantagem de proporcionar um melhor selamento apical em que todos os canais radiculares são selados hermeticamente, devido ao material ser facilmente introduzido até as irregularidades do sistema de canais radiculares. Contudo estas técnicas apresentam desvantagens como lesar o ligamento periodontal, cemento e osso alveolar devido à temperatura que é dissipada pela dentina ao sistema de canais radiculares e à elevada extrusão apical. Conclusão: Conclui-se então que o profissional tem que ter a consciência de que cada caso é um caso e como tal necessita de uma avaliação criteriosa de forma a saber que técnica escolher para a obturação dos canais radiculares. Introduction: Endodontics is an integrated science in the field of health sciences. Non-surgical endodontic treatment is divided into three major phases: Endodontic access, biomechanical preparation and obturation of root canals. Obturation is the final stage of non-surgical endodontic treatment and enables regeneration of periradicular tissues. Objective: The objective of this work is highlighting the importance of root canal system obturation, presenting some of the techniques used and evaluating the effects on periodontal tissues of the temperature variation and apical extrusion associated with thermoplastic obturation techniques. Materials and Methods: The study involved a literature review in the libraries of the Fernando Pessoa University and the Dentistry Faculty of the University of Porto and in the Pubmed, SciencDirect, SciElO, Google Scholar and B-on search engines. The key words used for the searches were: Temperature changes in obturation, temperature damages in obturation, filling gutta-percha extrusion, gutta-percha overfilling, warm obturation, leakage and endodontics, filling and endodontics, System B, Thermoplastic. The search was limited to review articles in English, Spanish and Portuguese, published between 1999 and 2013. Development: Thermoplastic techniques favour three-dimensional obturation of root canal systems, and lateral branches and apical deltas are frequently filled. These new techniques have the advantage of providing better apical sealing in which all root canals are hermetically sealed, because the material is easily inserted in the irregularities of the root canal system. However, these techniques have disadvantages, such as damaging the periodontal ligament, cementum and alveolar bone, due to the temperature that is dissipated by the dentine into the root canal system, and due to high apical extrusion. Conclusion: It is concluded that the professional must be aware that each case is different and careful evaluation is therefore required to assess which technique to use to fill root canals.

Tese de doutoramento - Programa Doutoral em Ciência e Engenharia de Polímeros e Compósitos
Free Form Extrusion (FFE) is a 3D fabrication process that involves depositing an extruded filament onto successive horizontal planes, in order to build a physic part with a specific geometry. The method is an adaptation of Fused Deposition Modeling (FDM), whereby a commercial pre-extruded ABS filament is replaced by a miniextruder capable of processing a wide range of materials, including homopolymers, polymer blends and nanocomposites. The mechanical performance of FFE parts is controlled by the bonding quality between adjacent filaments both in the horizontal and vertical plans. Adjacent filaments must be sufficiently hot to ensure adhesion, but should then cool down fast enough to avoid excessive deformation due to gravity and weight of the filaments on top. Therefore, it is important to know the evolution in time of the filaments temperature and how it is affected by the major process variables. Although several heat transfer models have been proposed in literature, most assume simplifications without verifying their effective importance. In this work, a detailed analysis of the contributions to the global heat transfer was made using the ABAQUS® software. Heat exchanges with ambient by convection and between adjacent filaments by conduction were found to be the most important. Consequently, these were taken in the energy balance, in order to obtain a rigorous FFE heat transfer analytical model. This analytical solution was then embedded into a routine capable of considering three different deposition patterns, for parts with specific geometries. Moreover, an adhesion criterion was implemented, in order to predict whether the operating conditions and deposition patterns selected for the manufacture of a given part are adequate. The deformation of the filaments was investigated by performing computational experiments with the ABAQUS® software, assuming a temperature dependent viscoelastic response. Since the maximum differences were shown to be quite small (< 0.2%), this phenomenon was considered negligible The consequence of this work is then a computer code that rigorously considers and inter-relates the three phenomena, with the potential of assisting the FFE user in selecting the ideal process parameters in order to obtain a part with good performance. This also allows testing the influence of many process variables and concluding about the most important.
Free Form Extrusion (FFE) é um processo 3D de fabricação que envolve a deposição de um filamento extrudido em planos horizontais sucessivos, por forma a obter uma peça com uma geometria específica. O método é uma adaptação do Fused Deposition Modelling (FDM), através do qual um filamento de ABS comercial pré-extrudido é substituído por uma mini-extrusora com a capacidade de processar uma grande variedade de materiais, incluindo homopolímeros, misturas de polímeros e nanocompósitos. O desempenho mecânico das peças obtidas através da técnica FFE é influenciado pela qualidade de adesão entre filamentos adjacentes, nos planos horizontais bem como verticais. Os filamentos adjacentes devem ser suficientemente quentes para assegurar a adesão, mas ter um arrefecimento suficientemente rápido para evitar a deformação excessiva devido à gravidade e ao peso dos filamentos posicionados nas camadas superiores. Consequentemente, é importante o conhecimento da evolução da temperatura dos filamentos em função do tempo, e como este é afetado pelas principais variáveis do processo. Apesar de vários modelos de transferência de calor terem sido propostos na literatura, na maior parte, simplificações são assumidas sem verificar a sua efetiva importância. Neste trabalho, uma análise detalhada dos intervenientes na transferência de calor foi elaborada usando o software ABAQUS®. Trocas de calor com o ambiente por convecção e entre filamentos adjacentes por condução mostraram ser os mais importantes. Consequentemente, estes foram incluídos no balanço de energia, a fim de obter um modelo analítico rigoroso de transferência de calor para o processo FFE. Esta solução analítica foi então incorporada numa rotina com a capacidade de considerar três tipos diferentes de deposição, para peças com geometrias específicas. Além disso, um critério de adesão foi implementado, a fim de prever se as condições operatórias e os tipos de deposição selecionados para a construção de uma dada peça são adequados A deformação dos filamentos foi investigada através da realização de experiências com o software computacional ABAQUS®, assumindo uma resposta viscoelástica dependente da temperatura. Uma vez que as diferenças máximas mostraram ser muito baixas (< 0.2%), este fenômeno foi considerado negligenciável. A consequência deste trabalho é portanto um código computacional que considera rigorosamente e inter-relaciona os três fenómenos, com a potencialidade de auxiliar o utilizador do processo FFE na seleção ideal dos parâmetros de processo, a fim de obter uma peça com bom desempenho. Também permite testar a influência de diversas variáveis de processo e concluir quais são as mais importantes.

碩士
國立清華大學
動力機械工程學系
103
The usage of 3D printing has become very popular in recent years due to its usefulness. Depending on the applicable purpose, it has been applied in many sectors; such as military, industrial, automotive, medical, art, food, etc. 3D printing is the process of making three-dimensional objects from a digital source into real physical products. The three most common types of 3D printer are extrusion type, granular type, and light polymerised type. Flexible varieties of material those can be used for 3D printing are ranging from thermoplastics, rubber, silicone, metal, thermoplastic powders to photopolymers. The scope of this thesis covers 3D printing with extrusion type and the results from implementing many different infill pattern strategies. 3D printer with extrusion type creates an object by slicing it into many stacked horizontal layers and uses infill to provide structural integrity by filling the internal section of an object in particular pattern. Proposed results were based upon qualitative research method combining simulation, mechatronic integration, and experimental verification to investigate how the different shapes of pattern and infill densities in the internal structure would affect the strength of the model. The result will offer additional knowledge for design engineer on selecting infill pattern to achieve optimum mechanical properties.

Ceramics have been extensively used in aerospace, automotive, medical, and energy industries due to their unique combination of mechanical, thermal, and chemical properties. The objective of this thesis is to develop an extrusion based ceramic 3D printing process to digitally produce a casting mold. To achieve the objective, an in-house designed ceramic 3D printer was developed by converting a filament based plastic 3D printer. For mold making applications, zircon was selected because it is an ultra-high temperature ceramic with high toughness and good refractory properties. Additionally, alumina, bioglass, and zirconia slurries were formulated and used as the feedstock material for the ceramic 3D printer.

The developed 3D printing system was used to demonstrate successful printing of special feature parts such as thin-walled high aspect ratio structures and biomimetically inspired complex structures. Also, proof of concept with regard to the application of 3D printing for producing zircon molds and casting of metal parts was also successfully demonstrated.

To characterize the printed parts, microhardness test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were conducted. The zircon samples showed an increase in hardness value with an initial increase in heat treatment temperature followed by a drop due to the development of porosity in the microstructure, caused by the decomposition of the binder. The peak hardness value for zircon was observed to be 101±10 HV0.2. Similarly, the microhardness values of the other 3D printed ceramic specimens were observed to increase from 37±3 to 112±5 HV0.2 for alumina, 23±5 to 35±1 HV0.2 for bioglass, and 22±5 to 31±3 HV0.2 for zirconia, before and after the heat-treatment process, respectively.

Finally, a system model for the ceramic 3D printing system was developed through the application of the model-based systems engineering (MBSE) approach using the MagicGrid framework. Through the system engineering effort, a logical level solution architecture was modeled, which captured the different system requirements, the system behaviors, and the system functionalities. Also, a traceability matrix for the system from a very abstract logical level to the definition of physical requirements for the subsystems was demonstrated.

Indiana University-Purdue University Indianapolis (IUPUI)
Ceramics have been extensively used in aerospace, automotive, medical, and energy industries due to their unique combination of mechanical, thermal, and chemical properties. The objective of this thesis is to develop an extrusion based ceramic 3D printing process to digitally produce a casting mold. To achieve the objective, an in-house designed ceramic 3D printer was developed by converting a filament based plastic 3D printer. For mold making applications, zircon was selected because it is an ultra-high temperature ceramic with high toughness and good refractory properties. Additionally, alumina, bioglass, and zirconia slurries were formulated and used as the feedstock material for the ceramic 3D printer. The developed 3D printing system was used to demonstrate successful printing of special feature parts such as thin-walled high aspect ratio structures and biomimetically inspired complex structures. Also, proof of concept with regard to the application of 3D printing for producing zircon molds and casting of metal parts was also successfully demonstrated. To characterize the printed parts, microhardness test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were conducted. The zircon samples showed an increase in hardness value with an initial increase in heat treatment temperature followed by a drop due to the development of porosity in the microstructure, caused by the decomposition of the binder. The peak hardness value for zircon was observed to be 101±10 HV0.2. Similarly, the microhardness values of the other 3D printed ceramic specimens were observed to increase from 37±3 to 112±5 HV0.2 for alumina, 23±5 to 35±1 HV0.2 for bioglass, and 22±5 to 31±3 HV0.2 for zirconia, before and after the heat-treatment process, respectively. Finally, a system model for the ceramic 3D printing system was developed through the application of the model-based systems engineering (MBSE) approach using the MagicGrid framework. Through the system engineering effort, a logical level solution architecture was modeled, which captured the different system requirements, the system behaviors, and the system functionalities. Also, a traceability matrix for the system from a very abstract logical level to the definition of physical requirements for the subsystems was demonstrated.