Dissertations / Theses on the topic 'High pressure soot formation'

Die Rußbildung in der Pyrolyse von n-Hexan, Benzol und Kohlenwasserstoffen im Stoßrohr wird mit hoher Zeitauflösung absorptionsspektroskopisch beobachtet und Gasproben durch ein besonders schnelles Ventil gesammelt. Vom Beginn der Pyrolyse bis zum Einsetzen der Rußbildung wurde stets eine Induktionszeit beobachtet, deren Dauer von der Temperatur, der Kohlenstoffkonzentration und der Struktur des pyrolysierten Kohlenwasserstoffs abhängt. Dieser Zusammenhang wird mit einem Arrhenius-Ansatz beschrieben. Der Vorfaktor A ist für Aromaten eine Größenordnung kleiner als für Alkane. Die scheinbare Aktivierungsenergie beträgt (220 ± 10) kJ/mol. Das Rußmassenwachstum, das der Induktionsperiode folgt, wird mit einem Gesetz erster Ordnung beschrieben. Durch Normierung der Geschwindigkeitskonstanten auf die Kohlenstoffdichte zeigt, daß das Rußmassenwachstum in Pyrolysen und in vorgemischten Ethylenflammen vergleichbar schnell abläuft. Die Rußausbeute der Aromaten und Acetylen hat bei bei 1800 K ein Maximum. Für Ethylen und Alkane liegt diese charakteristische Temperatur um rund 100 K höher. Neben Ruß und Wasserstoff sind Acetylen gefolgt von Methan und Ethylen die wichtigsten Hauptprodukte. Die polycyclischen Aromaten tragen keine Seitengruppe und enthalten maximal einen Fünfring. Der Rußpartikeldurchmesser ist im Bereich von 30 nm. Der Einfluß von Eisenpentacarbonyl auf die Rußbildung ist gering.

The objective of this thesis is to develop and validate a model of soot formation which is capable of being applied to a computational fluid dynamic (CFD) simulation of gas turbine combustion. The work follows previous research by Moss and Co-workers (Moss et al.1987, Syed 1990, Stewart et al.1991) The concept of the study is to generate a detailed set of experimental data in turbulent flames of kerosine in which the complicating factors of gas turbine combustion - that is 3D geometry and droplet combustion - are removed. This allows more confidence in the computational simulation of the flames and therefore more insight into the soot formation process. There are two components to the work: the experimental and theoretical studies. The first involves the compilation of an experimental dataset of key variables in ethylene and vaporised kerosine jet flames at elevated pressure, the second with the simulation of two of the experimentally studied flames using CFD methods. The main achievement of the study is the generation of a formidable and detailed experimental database for flames at a variety of pressures and conditions. The unexpected finding is the extremely large conversion of carbon to soot found in the flames even at low pressure. This results in high radiant heat losses and measurement difficulties. From the data, it is possible to assess the pressure dependence of soot growth in kerosine flames. Although, at the higher pressures, high soot levels created uncertainties in the measurements, in absolute terms growth rate is shown to be independent of pressure up to 6atm pressure. Above this it increases significantly. The soot model of Moss et al.1988 - originally developed in laminar e~hylene flames - was shown to give excellent agreement in turbulent situations. However, owing to the large radiant heat loss and soot levels, its application to the kerosine flames was more problematic since the assumptions that soot is a perturbation to the gaseous field and that temperature may be accurately described by a single perturbed flamelet were no longer valid. Further models to deal with such situations are proposed and tested. Aside from the obvious relevance of this study to the field of gas turbine combustion, the large radiant heat loss and high soot levels observed in the flames studied here imply a further significance for the study of fire hazards. That a laboratory scale flame maybe made to behave in a similar manner to a much larger pool fire flame is a very useful finding.

Soot volume fraction (f_sv) is measured quantitatively in a laminar diffusion flame at elevated pressures up to 25 atmospheres as a function of fuel type in order to gain a better understanding of the effects of pressure on the soot formation process. Methane and ethylene are used as fuels; methane is chosen since it is the simplest hydrocarbon while ethylene represents a larger hydrocarbon with a higher propensity to soot. Soot continues to be of interest because it is a sensitive indicator of the interactions between combustion chemistry and fluid mechanics and a known pollutant. To examine the effects of increased pressure on soot formation, Laser Induced Incandescence (LII) is used to obtain the desired temporally and spatially resolved, instantaneous f_sv measurements as the pressure is incrementally increased up to 25 atmospheres. The effects of pressure on the physical characteristics of the flame are also observed. A laser light extinction method that accounts for signal trapping and laser attenuation is used for calibration that results in quantitative results. The local peak f_sv is found to scale with pressure as p^1.2 for methane and p^1.7 for ethylene.

The effects of elevated pressure and high heating rates on coal pyrolysis and gasification were investigated. A high-pressure flat-flame burner (HPFFB) was designed and built to conduct these studies. The HPFFB was designed to provide an environment with laminar, dispersed entrained flow, with particle heating rates of ~10^5 K/s, pressures of up to 15 atm, and gas temperatures of up to 2000 K. Residence times were varied from 30 to 700 ms in this study. Pyrolysis experiments were conducted at particle heating rates of ~10^5 K/s and maximum gas temperatures of ~1700 K at pressures of 1 to 15 atm. A new coal swelling correlation was developed that predicts the effects of heating rate, pressure, and coal rank on the swelling ratio at heating rates above ~10^4 K/s. A coal swelling rank index system based on 13C-NMR chemical structural parameters was devised. The empirical swelling model requires user inputs of the coal ultimate and proximate analyses and the use of a transient particle energy balance to predict the maximum particle heating rate. The swelling model was used to explain differences in previously reported bituminous coal swelling ratios that were measured in facilities with different heating rates. Char gasification studies by CO2 were conducted on a subbituminous coal and 4 bituminous coals in the HPFFB. Pressures of 5, 10, and 15 atmospheres were used with gas compositions of 20, 40, and 90 mole % CO2. Gas conditions with peak temperatures of 1700 K to 2000 K were used, which resulted in char particle temperatures of 1000 K to 1800 K. Three gasification models were developed to fit and analyze the gasification data. A simple 1st-order model was used to show that the measured gasification rates were far below the film-diffusion limit. The other two models, designated CCK and CCKN, were based on three versions of the CBK models. CCKN used an nth-order kinetic mechanism and CCK used a semi-global Langmuir-Hinshelwood kinetic mechanism. The two CCK models fit the HPFFB gasification data better than the 1st-order model. The fits of the gasification data with CCK and CCKN were comparable to each other. The fit of the data in CCK suggests that Knudsen diffusion may have influenced the gasification rates in the HPFFB experiments. The gasification rate parameters in each of the three models were correlated with coal rank. 13C-NMR parameters were used to estimate a structural parameter of the coal char. Char-CO2 gasification rate coefficients correlated better with this NMR-based char structure index than it did with the carbon and oxygen content of the parent coal.

This thesis is an experimental investigation of the phase behavior, volumetric properties, and viscosity of poly (methyl methacrylate) (PMMA), poly (ε-caprolactone) (PCL) and their blends. Homopolymerization and copolymerizations of methyl methacrylate (MMA) and 2-methylene-1,3-dioxepane (MDO) in mixtures of acetone + CO2 have also been explored. The viscosities and densities of acetone + CO2 mixtures were measured in the temperature range 323-398 K at pressures up to 35 MPa. This is the first study in which viscosity of acetone + CO2 mixtures have been measured and the mixtures have been evaluated as solvents for PCL. It is shown that PCL can be readily dissolved in these fluid mixtures at modest pressures even at high carbon dioxide levels. Investigations have been conducted over a temperature range from 323 to 398 K at pressures up to 50 MPa for polymer concentrations up to 20 wt %, and CO2 concentrations up to 60 wt %. It is shown that in these mixtures PCL is dissolved at pressures that are much lower than the pressures reported for miscibility in the mixtures of carbon dioxide with other organic solvents. It is shown that PMMA also readily dissolves at modest pressures. Blends of PMMA and PCL require higher pressures than for the individual polymers for complete miscibility. Free-radical polymerizations of MMA in acetone at 343 K were followed using in-situ measurements of viscosity and density at different pressures from 7- 42 MPa. This is the first time viscosity has been used as a real-time probe of high pressure polymerizations. Two distinct kinetic regimes were identified. Homopolymerizations of MDO were conducted in carbon dioxide at 323 and 343 K at pressures up to 42 MPa. For the first time it is shown that high molecular weight PCL can be produced from MDO in high pressure CO2. Ring-opening free-radical copolymerizations of MDO with MMA, styrene and acrylonitrile were conducted for the first time in carbon dioxide and have been shown to lead to polymers with high molecular weights.
Ph. D.

Dans cette thèse, un modèle de la dynamique du plasma après un claquage microonde dans l'air à pression atmosphérique a été développé. Ce modèle a permis d'expliquer pour la première fois la formation et la dynamique de structures filamentaires auto-organisées lors du claquage microonde. Le claquage microonde dans l'air à pression atmosphérique a été récemment observé au MIT dans des expériences mettant en oeuvre une source microonde de puissance et des caméras rapides. Les mesures montrent que, lors du claquage, un ensemble structuré de filaments de plasma se forme et se dirige vers la source à une vitesse de plusieurs km/s. Les mécanismes de formation et de propagation de ces structures auto-organisées de plasma ne sont pas bien compris et l'objectif de cette thèse a été de mettre en évidence et de modéliser les phénomènes physiques de base qui en sont responsables. Dans le but de décrire la dynamique du plasma après claquage, les équations de Maxwell ont été couplées à un modèle simple de plasma et résolues numériquement. Le modèle de plasma suppose la quasineutralité et décrit l'évolution de la densité de plasma sous l'effet de la diffusion, de l'ionisation, de l'attachement et de la recombinaison électron-ion. L'ionisation et l'attachement sont supposés dépendre du champ électrique effectif local. La vitesse moyenne électronique est déduite d'une équation de transport de quantité de mouvement simplifiée. La diffusion des particules chargées est ambipolaire au sein du plasma mais devient libre dans le front où la densité chute à zéro. Une expression heuristique de la transition entre diffusion ambipolaire dans le corps du plasma et diffusion libre sur les bords a été établie et validée à l'aide d'un modèle mono-dimensionnel de type dérive-diffusion-Poisson que nous avons développé et dans lequel on ne suppose pas la quasineutralité du plasma. Le modèle plasma-Maxwell quasineutre a ensuite été utilisé pour étudier la dynamique du plasma après claquage dans les conditions des expériences du MIT. Les résultats numériques montrent la formation de structures filamentaires auto-organisées de plasma en excellent accord qualitatif avec les observations expérimentales. Ces structures auto-organisées sont liées aux structures du champ électrique diffracté par le plasma. De nouveaux filaments se forment de façon continue dans le front du plasma par des phénomènes de diffusion-ionisation. Le modèle montre que la formation d'un réseau de filaments de plasma auto-organisé est dû à l'apparition des maxima de champ électrique de l'onde stationnaire formée dans le front du plasma. Dans la dernière partie de la thèse, la formation d'un filament de plasma isolé (ou streamer microonde) au maximum de champ formé à l'intersection de deux faisceaux microondes est analysée à l'aide du modèle. Le streamer microonde s'allonge parallèlement à la direction du champ en raison du renforcement du champ à ses pôles (phénomène de polarisation). L'intensité du champ aux extrémités du filament est modulée dans le temps en raison de phénomènes de résonance pour des longueurs de filaments voisines de multiples de la demi longueur d'onde.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Valkó e Oligney propuseram um modelo que estima a evolução da fratura utilizando uma interpretação direta da curva de pressão de fundo medida durante uma operação de fracpack. Os únicos dados de entrada necessários para a aplicação do modelo são os registros geralmente disponíveis durante e após a operação. Considerando uma fratura de geometria radial e utilizando equações simples de fluxo e de geomecânica, o modelo obtém raios de empacotamento a partir da inclinação positiva da curva de pressão de fundo nos períodos de tip screenout. Nesta dissertação o modelo de Valkó e Oligney é aprimorado com a inclusão e o ajuste das equações de estado para o crescimento da fratura e para o processo de filtração, respectivamente. O modelo é também estendido para outras geometrias bidimensionais de fratura, PKN e KGD. A aplicação do modelo foi realizada utilizando os registros de pressão de oito operações de fracpack. Os resultados obtidos são a curva de propagação da fratura, o crescimento da abertura, a eficiência ao longo do tempo e a distribuição final do agente de sustentação na fratura. Para a validação desses resultados foram utilizados dois simuladores comerciais com modelos tridimensionais. Os estudos de caso indicaram que os ajustes realizados aproximaram os resultados do modelo aos obtidos nos simuladores comerciais. Além disso, a aplicação dos modelos desenvolvidos para cada geometria de fratura e a comparação com os resultados dos simuladores comerciais, permitiu confirmar a tendência esperada que, durante uma operação de fracpack, a geometria da fratura se aproxima da radial.
Valkó and Oligney developed a model to estimate fracture evolution using a direct interpretation of the measured bottom hole pressure curve during a fracpack operation. The only input data needed to use the model are the usual records of the job, available during and after the operation. Considering radial fracture geometry and using simplified equations of flow and geomechanics, the model estimates a packing radius of the fracture using the slope of the increasing bottom hole pressure curve during the tip screenout period. In this work, Valkó and Oligney method is enhanced with the inclusion of state equations for the fracture growth and for the leakoff process in order to improve the model, but still maintaining minimum input data. The method is also extended to other two-dimensional fracture geometries, PKN and KGD. To apply the enhanced method, eight fracpack operation data were used. The results obtained are fracture propagation, width growth and fluid efficiency in time as well as the final proppant distribution in the fracture. To validate these results, this work used two commercial simulators with three-dimensional models. The case studies show that the modifications done to Valkó and Oligney method approximate the two-dimensional model results to the ones obtained using the commercial simulators with threedimensional models. Furthermore, the comparison between the application of the model for each fracture geometry and the commercial simulators results confirmed the expected tendency for the fracture geometry during a fracpack operation, which is a radial fracture.

The interaction of hydrogen with metals has great environmental significance in problems ranging from the catastrophic failure of materials due to hydrogen embrittlement to safe and efficient storage of hydrogen as a metal hydride. Chromium (Cr) is widely used as an alloying agent to produce materials such as stainless steel and as an electroplated coating on materials to prevent corrosion and to minimize wear. Hydrogen which co-deposits with chromium during electroplating forms hexagonal close packed CrH or face centered cubic CrH2 which cracks the deposit. The behavior of hydrogen in Cr, especially the crystal structure modifications of metal Cr when it is exposed to hot, dense hydrogen gas is not completely understood. In equilibrium study, chromium hydride has been found of hexagonal close packed structure under 400 °C with high hydrogen pressure. Experiments at higher temperatures are limited by the equipment and technology. This dissertation describes a novel, non-equilibrium method which was used to synthesize a new chromium hydride phase. Single crystal, body centered cubic Cr thin films were prepared by vacuum evaporation. These films were exposed to high temperature (close to the melting point of Cr), high pressure hydrogen gas in a ballistic compressor. This was followed by rapid cooling (>105 ˚C/s) to room temperature. Using the transmission electron microscope (TEM), second phase particles of superhexagonal structure, which has lattice constant A=4.77Å and C/A=1.84, are found in the films. This structure has a volume per Cr atom slightly larger than that of hexagonal closed packed CrH, so that the superhexagonal structure may contain more hydrogen than the hexagonal close packed CrH. The superhexagonal particles have a definite orientation relationship with the matrix: [021][subscript sh] II [OOl][subscript b] and (212)[subscript sh] II (IIO)[subscript ]b. The superhexagonal structure is quite stable in air and at room temperature, but decomposes to body centered cubic Cr when heated by the electron beam illumination in the TEM. No such particles were observed in Cr films exposed to pure argon under similar conditions in the ballistic compressor. Positive identification of hydrogen content was obtained by high-temperature vacuum extraction in a discharge tube. After vacuum extraction, hydrogen spectrum was observed, and the intensity of electron diffraction from superhexagonal structure decreased. Using an energy dispersive spectrometer with the capability of detecting elements down to atomic number six (carbon), no changes in composition of the films were found by comparing the characteristic x-ray spectra of the same film before and after exposure to hot, dense hydrogen in the ballistic compressor. This result suggests that this non-equilibrium method may be used for other metal-hydrogen systems to obtain new structural phases that are of scientific or technological interest.

High-pressure die casting of semi-solid aluminium-silicon alloys is used in the automotive industry to manufacture components, like housings, brackets, and bars. It is commonly known that during high-pressure die casting, defect bands may be created that follow the contour of the component surface. These bands consist mainly of a eutectic phase. This phenomenon is also observed in semi-solid metal slurry high-pressure die casting. These bands could lead to premature failure of the component in service. The origin of these bands is not fully understood and so this research focuses on investigating these bands and their origins further. A series of casting trials were conducted with varying plunger velocity. Subsequent investigation using optical and scanning electron microscopy showed that a change of the plunger velocity alters the number of bands present in the samples. Energy dispersive X-ray spectroscopy revealed that a measurable difference in aluminium quantity across the band was noticed and it was postulated that aluminium migrates towards the component centre. Therefore, different mechanisms responsible for particle migrations found in literature were investigated and assessed quantitatively using experimental data and information from published literature. It was found that the Saffman lift force and the Mukai-Lin-Laplace effect were the mechanisms that were most likely to cause such a migration of aluminium. Further experimental investigation is recommended to identify which of the two mechanisms is ultimately responsible for the migration and to optimise the high-pressure die casting procedure to minimise defect band formation.
Produktion av högtrycksgjutning av halvfasta aluminium-kisellegeringar används i fordonsindustrin för att tillverka komponenter, som exempel till kåpor, konsoler och stag. Det är allmänt känt att defektband kan formas under högtrycksgjutning som följer konturen av komponentytan. Dessa band består huvudsakligen av eutektisk fas. Detta fenomen har också observerats vid högtrycksgjutning produktion av halvfast slurry. Potentiellt kan dessa band leda till en försämring av komponentens mekaniska egenskaper och resultera i ett förtida brott. Ursprunget av dessa band är inte helt kartlagda och det är därför viktigt att fokusera ytterligare på denna forskning och att undersöka dessa band och deras ursprung. En serie med gjutningsförsök genomfördes med varierande kolvhastighet. Efterföljande undersökning med optisk- och svepelektronmikroskopi visade att en förändring av kolvhastigheten förändrar antalet band som finns i proverna. Energidispersiv röntgenspektroskopi avslöjade en mätbar skillnad i aluminiumkvantitet över bandet, och det antogs att aluminium migrerar mot centrum av komponenten. Därför undersöktes och utvärderades olika mekanismer som ansvarar för partikelmigrationer som finns att finna i litteratur med hjälp av experimentella data och information från publicerad litteratur. Det visade sig att Saffman lyftkraft och Mukai-Lin-Laplace effekten var de mekanismer som mest troligen orsakade migration av aluminium. Ytterligare experimentella försök rekommenderas för att identifiera vilken av dessa två mekanismerna som i slutändan är ansvarig för migrationen. Detta för att optimera gjutningsprocessen och därmed minimera uppkomsten av defektband.

I present spectroscopic imaging of the high-velocity system (HVS) towards the central cD galaxy (NGC 1275) in the Perseus Cluster at a high spectral resolution for the first time. Previous observation suggests that the HVS is a highly inclined dusty and gas-rich galaxy moving towards the center of NGC 1275 at a high speed of 3000 km/s relative to the systemic velocity of NGC 1275 through the hot intracluster medium (ICM). If this is the case, then the HVS should be undergoing intense ram-pressure stripping. However, there is tentative evidence for ram-pressure stripping in the HVS, and furthermore confined to a small region of the galaxy. Previous observations also point out that at the location where the HVS is seen, there are many star clusters seen towards the inner region of NGC 1275. The separation of young star clusters between those belong to NGC 1275 and those belong to the HVS is, however, not clearly defined. The primary scientific objectives are to (i) search for evidence for ram-pressure stripping in the HVS, as well as signs of tidal interactions between the HVS and NGC 1275; and (ii) separate the numerous young star clusters seen towards the entire NGC 1275 into those associated with the HVS and those associated with NGC 1275. NGC 1275 and the HVS were observed simultaneously with the use of Potsdam Multi-Aperture Spectrophotometer. The main emission lines being studied are the Hα & [NII]λ6548,6483 lines in NGC 1275 and the HVS. I present maps of intensity distribution, velocity field and velocity dispersion of the Hαemission of the HVS, as well as the line ratio of the [NII] doublets lines to the Hα line in the HVS. I find that the line ratio of [NII]/Hα is less than 0.1 throughout the entire body of the HVS, indicating metallicity is low in the HVS. I also find that the metallicity is decreasing with distance from the center, just like other normal spiral galaxies. I demonstrate that a large fraction of the young star clusters seen towards the inner regions of NGC 1275 are closely associated with bright Hα-emitting regions in the HVS, and trace the overall Hα-emitting body of the HVS, suggesting that some young star clusters are associated to the HVS. I find that there are two distributions of young star clusters in color-color space, providing a way to separate out the star clusters likely belong to the HVS. I present evidence that the HVS is experiencing intense ram-pressure stripping and also evidence suggesting that the HVS is possibly tidally interacting with NGC 1275. The results demonstrate that the HVS is a dusty, gas-rich, low-metallicity galaxy that has been disrupted by ram-pressure stripping and possibly also tidal interactions. I show that the HVS exhibit widespread and vigorous (~3.6 MM_⊙ yr^(-1)) star formation over the last at least ~0.1 Gyr. The vigorous SFR of the HVS is in contrast to what suggested by the observed low metallicity (suggestive of relatively weak star-formation activity over the recent history). The SFR of the HVS is likely to be triggered by the same process that produces global distortion on the HVS, here ram pressure stripping and possibly tidal interaction are in consideration.
published_or_final_version
Physics
Master
Master of Philosophy

El objetivo comprendido en esta tesis doctoral fue evaluar el efecto de la aplicación de la Alta Presión Hidrostática (APH) en la formación de Aminas Biogenas (AB) en quesos elaborados a partir de leche cruda. Para este propósito fue necesaria la participación de dos queserías artesanas como proveedoras de las dos variedades de queso elaboradas a partir de leche cruda utilizadas en este estudio, una de leche de oveja y otra de de leche de cabra. La visita a cada una de las queserías se realizó previamente con el fin de conocer las instalaciones, las condiciones de elaboración de los quesos y el grado de cumplimiento de la gestión del autocontrol. Los quesos fueron ajustados a las dimensiones de la canasta del equipo de APH, envasados al vacío y tratados por APH a 400 MPa de presión, durante 10 min, y 2 ºC de temperatura. Estas condiciones fueron aplicadas a los quesos entre los días 3 y 7 (APH1) y al día 15 (APH15) después de la elaboración. En cada caso se realizaron, durante la maduración, los análisis necesarios para conocer el efecto de cada tratamiento en la microbiología, los parámetros fisicoquímicos, el contenido de AB y las características sensoriales y de textura de los quesos. Así mismo, se estudió la capacidad formadora de AB en la microbiota presente en cada una de las variedades de queso. Para este propósito se realizó la validación de un método cualitativo para la detección de bacterias con actividad aminoácido decarboxilasa y se evaluó la frecuencia de las diferentes especies y cepas bacterianas encontradas con esta capacidad. El sistema de higiene y calidad basado en los principios del análisis de peligros y puntos críticos de control (APPCC) observado en cada quesería participante no está propiamente implantado. Sin embargo en ambas queserías se aplica, de diferentes maneras, el programa de pre-requisitos, aunque en algunos casos estos procedimientos y controles no estén por escrito y/o registrados. Los principales puntos débiles encontrados en ambas queserías fueron: El mantenimiento preventivo de instalaciones y equipos; los procedimientos de limpieza y desinfección; y la gestión y eliminación del lactosuero. Adicionalmente, en una de las queserías se observó que el control de la calidad del agua suministrada era inadecuado. En ambos tipos de queso se observó que la aplicación de APH influyó en el contenido de AB, mostrando una reducción, en comparación con la muestra control, alrededor del 75 y 35% en los quesos con tratamiento APH1 y APH15, respectivamente. La tiramina (TY) y la putrescina (PU) fueron las aminas más afectadas en los quesos elaborados de leche cruda de cabra, mientras que la TY y la cadaverina (CA) lo fueron en los quesos de leche cruda de oveja. La disminución en la concentración AB en los quesos presurizados al inicio de la maduración pudo deberse a la reducción observada en los recuentos microbianos un día después de la aplicación del tratamiento (principalmente lactococos, lactobacilos, enterococos y enterobacterias), junto con en el descenso del contenido de aminoácidos libres percibido, 34 y 48% menor que el obtenido en los quesos control de leche de cabra y oveja al final de la maduración, respectivamente. Por otro lado, la aplicación del tratamiento APH15 mostró también una reducción significativa en los recuentos microbianos. Sin embargo el contenido de aminoácidos libres observado fue similar a los quesos control. Los dos medios decarboxilantes, bajo en nitrógeno (LND) y bajo en glucosa (LGD), utilizados en el método cualitativo para la detección de bacterias con actividad aminoácido decarboxilasa mostraron parámetros de diagnostico satisfactorios para la identificación de bacterias con la capacidad de formar PU, CA y TY, siendo su optimo punto de corte fijado entre 10-25 mg L-1, con un área bajo la curva ROC superior al 0,90 y unos valores de sensibilidad y especificidad superiores al 84 y 92%, respectivamente. No obstante, este método mostró menor capacidad en la detección de bacterias con la habilidad de producir HI, siendo considerada, de acuerdo con los parámetros de diagnostico evaluados, como aceptable y deficiente, para los medios LND y LGD, respectivamente. La mayor actividad aminoácido decarboxilasa observada entre las bacterias aisladas de los quesos de leche de cabra y oveja fue la tirosina decarboxilasa, con una capacidad de producción de TY superior a 100 mg L-1, seguida por la lisina y la ornitina decarboxilasa, con una habilidad de formación de CA y PU en concentraciones de 100-1000 mg L-1 y superiores a 1000 mg L-1, respectivamente. Los principales microorganismos productores de TY mostraron ser aquellos pertenecientes a los grupos de Lactococcus, Lactobacillus, Enterococcus y Leuconostoc, mientras que las cepas bacterianas de Enterobactericeae y Staphylococcus fueron las principales formadoras de CA y PU, aunque algunas cepas de Enterococcus, Lactococcus, Leuconostoc, y Pediococcus mostraron tener capacidad de producir diaminas a niveles superiores de 100 mg L-1. En lo referente a las características sensoriales y de textura, los quesos tratados con APH muestran una reducción de la fracturabilidad. Este hecho pudo ser debido a los cambios en la microestructura causados por la aplicación de APH y, en el caso de los quesos presurizados, al inicio de la maduración posiblemente también a la disminución en la velocidad de proteólisis producida. Por otro lado, en la evaluación sensorial de la textura, las diferencias significativas percibidas fueron únicamente encontradas en la firmeza de los quesos, siendo consideradas las muestras presurizadas como más firmes que los quesos control. La determinación de color mostró que la diferencia total (ΔE) de las muestras tratadas en comparación con los controles fue mayor después de la aplicación de APH (alrededor de 4.4), sin embargo esta diferencia fue disminuyendo a medida que la maduración avanzaba. Así mismo, la diferencia de color percibida por el panel de evaluación sensorial, fue significativa únicamente en las muestras de leche de oveja con tratamiento APH1.
The aim of this work was to evaluate the effect of the High Hydrostatic Pressure (HHP) on the formation of Biogenic Amines (BA) in raw milk cheeses. For this purpose, two Spanish artisan cheese factories were selected to provide the cheeses to be used in the survey. These factories were previously visited to check the compliance with the hygienic standards required by European Regulations. One variety of cheese was chosen from each factory, both made from raw milk. One of them was made from ovine milk and the other from caprine milk. A HHP treatment of 400 MPa during 10 min at 2 ºC was chosen as the most suitable. These conditions were applied at the begging of the ripening between 3rd and 7th day (HHP1) or on the 15th day (HHP15), in each case the effect of the treatments on the microbial, physicochemical, textural, and sensory parameters, as well as on the formation of different BA were assessed during the maturity period. The BA forming capacity of the microbiota present in the cheeses was also evaluated. To this purpose a qualitative screening method to detect the amino acid decarboxylase activity of bacteria was validated and the frequency of the different species and strains with this capacity was determined in either the ovine and caprine raw milk cheeses studied. The hygienic quality system based on the HACCP principles of the two visited artisan cheese factories was not strictly established. However, the prerequisites program was applied according to their necessities, although in most cases the procedures and results of the controls were not appropriately written or registered. The preventive maintenance of the facilities and equipments, cleaning and sanitation procedures, and the whey waste disposal were the main weaknesses found in both cheese factories. Besides, the water supply control was also unsuitable in one of them. Biogenic amine content in both types of cheeses was greatly influenced by HHP. The treatments applied on the beginning and on the 15th day of ripening displayed 75 and 35% lower amounts of BA, respectively, than those obtained in the control untreated samples, being TY and PU the most affected amines in caprine milk cheeses, while TY and CA were so in ovine milk cheeses. The BA reduction in the caprine and ovine HHP1-samples can be explained as a result of a significant decrease of microbiological counts observed one day after the HHP-treatment (specially in the lactoccocci, lactobacilli, enteroccocci and enterobacteria groups) and the slower proteolysis detected in these samples, which showed 34 and 48% less free amino acids than the control caprine and ovine milk cheese samples at the 60th day of ripening, respectively. On the other hand, the HHP treatment applied on the 15th day also resulted in the decrease of microbiological counts, although in this case the liberation of amino acids was not different than the control samples. The amino acid decarboxylase microplate screening method using low nitrogen decaboxylase (LND) and low glucose decaboxylase (LGD) broths had satisfying diagnostic parameters to detect the PU, CA and TY- forming bacteria, being their optimal cut off between 10-25 mg L-1, with an area under ROC curve above 0.90 and a sensitivity and specificity values above 84 and 92%, respectively. Nevertheless, the test had less capacity to detect the HI-forming bacteria. According to the diagnosis parameters evaluated, this test was considered only as acceptable and poor, for LND snd LGD media, respectively. Among the isolates obtained from caprine and ovine milk cheeses with amino acid decarboxylase activity, the TY forming bacteria were the most frequent, showing a strong production (exceeding 100 mg L-1), followed by those with CA and PU-forming ability with strong and prolific production (100-1000 and over 1000 mg L-1, respectively). In the first case, strains belonging to the Lactococcus, Lactobacillus, Enterococcus and Leuconostoc groups were found as the main TY producers, whereas Enterobactericeae and Staphylococcus strains were the main PU and/or CA forming bacteria, although some Enterococcus, Lactococcus, Leuconostoc, and Pediococcus strains showed an ability to produce diamines at levels above 100 mg L-1. The decelerated rate of proteolysis in HHP1 samples, combined with the structural changes caused by the pressure, could contribute to reduce the fracturability of cheeses. However, this decrease could be only due to the formation of a more homogeneous microstructure in the ovine milk cheeses with the HHP15 treatment. The sensory panel noticed that the firmness in the HHP1 and HHP15 samples was significantly different than in control samples. The total color differences (ΔE) in the HHP samples was higher during the first stages of the ripening (around 4.4 in HHP1 and HHP15 samples), decreasing as the sample aged. In addition, differences in color were also perceived by the sensory panel, being significant only in ovine milk cheeses with the HHP1-treatment.

This study addresses the influence of elevated pressures, fuel type, fuel flow rate and co-flow air on the flame structure and flickering behaviour of laminar oscillating diffusion flames. Photomultipliers, high speed photography and schlieren, accompanied with digital image processing techniques have been used to study the flame dynamics. Furthermore, the effects of pressure on the flame geometry and two-dimensional soot temperature distribution in a laminar stable diffusion flame have been investigated, utilising narrow band photography and two-colour pyrometry technique in the near infra-red region. This study provides a broad dataset on the diffusion (sooty) flame properties under pressures from atmospheric to 16 bar for three gaseous hydrocarbon fuels (methane, ethylene and propane) in a co-flow burner facility.It has been observed that the flame properties are very sensitive to the fuel type and flow rate at elevated pressures. The cross-sectional area of the stable flame shows an average inverse dependence on pressure to the power of n, where n was found to be 0.8±0.2 for ethylene flame, 0.5±0.1 for methane flame and 0.6±0.1 for propane flame. The height of a flame increases firstly with pressure and then decreases with further increase of pressure. It is observed that the region of stable combustion was markedly reduced as pressure was increased. An ethylene flame flickers with at least three dominant modes, each with corresponding harmonics at elevated pressures. In contrast, methane flames flicker with one dominant frequency and as many as six harmonic modes at elevated pressures. The increase in fuel flow rate was observed to increase the magnitude of oscillation. The flickering frequency, however, remains almost constant at each pressure. The dominant flickering frequency of a methane diffusion flame shows a power-law dependence on chamber pressure.It has been observed that the flame dynamics and stability are also strongly affected by the co-flow air velocity. When the co-flow velocity reached a certain value, the buoyancy driven flame oscillation was completely suppressed. The schlieren imaging has revealed that the co-flow of air is able to push the initiation point of outer toroidal vortices beyond the visible flame to create a very stable flame. The oscillation frequency was observed to increase linearly with the air co-flow rate. The soot temperature results obtained by applying the two-colour method in the near infra-red region shows that in diffusion flames the overall temperatures decrease with increasing pressure. It is shown that the rate of temperature drop is greater for a pressure increase at lower pressures in comparison with higher pressures.

The theory of the abyssal abiotic petroleum origin considers oil and natural gas to begenerated in the Earth’s upper mantle. Hydrocarbons migrate further through the deep faults into the Earth’s crust, where they can form oil and gas deposits in any kind of rock in any kind of structural position. Until recently one of the main obstacles for further development of this theory has been the lack of the data covering processes of generation and transformations of hydrocarbons. Experimental data, presented in this thesis, confirms the possibility of hydrocarbons formation from mantle inorganic compounds (water, Fe, CaCO3 or graphite) at temperature and pressure of the upper mantle (1500 K and 5 GPa). Experiments were carried out in CONAC high pressure device and multianvil apparatus BARS. Compositions of received gas mixtures were similar to natural gas. Quantity of hydrocarbons depended on the cooling regime of reaction mixture under pressure. Slow cooling favored higher quantity. We found that donor of carbon (CaCO3 or graphite) determines formation of “dry” (methane-rich) gas or “wet” (light hydrocarbons-rich) gas. Experiments in laser-heated diamond anvil cells showed that methane and ethane partially react under upper mantle thermobaric conditions (2-5 GPa, 1000-1500 K) to form mixture of hydrocarbons: methane, ethane, propane and n-butane – main compounds of natural gas. Similarity of final product mixture obtained from methane and ethane means thermodynamic stability of hydrocarbons in the thermobaric conditions of the upper mantle and equilibrium character of the observed processes.
QC 20101203

Methane hydrate nucleation and growth in porous model carbon materials illuminates the way towards the design of an optimized solid-based methane storage technology. High-pressure methane adsorption studies on pre-humidified carbons with well-defined and uniform porosity show that methane hydrate formation in confined nanospace can take place at relatively low pressures, even below 3 MPa CH4, depending on the pore size and the adsorption temperature. The methane hydrate nucleation and growth is highly promoted at temperatures below the water freezing point, due to the lower activation energy in ice vs. liquid water. The methane storage capacity via hydrate formation increases with an increase in the pore size up to an optimum value for the 25 nm pore size model-carbon, with a 173% improvement in the adsorption capacity as compared to the dry sample. Synchrotron X-ray powder diffraction measurements (SXRPD) confirm the formation of methane hydrates with a sI structure, in close agreement with natural hydrates. Furthermore, SXRPD data anticipate a certain contraction of the unit cell parameter for methane hydrates grown in small pores.

Methane hydrate nucleation and growth in porous model carbon materials illuminates the way towards the design of an optimized solid-based methane storage technology. High-pressure methane adsorption studies on pre-humidified carbons with well-defined and uniform porosity show that methane hydrate formation in confined nanospace can take place at relatively low pressures, even below 3 MPa CH4, depending on the pore size and the adsorption temperature. The methane hydrate nucleation and growth is highly promoted at temperatures below the water freezing point, due to the lower activation energy in ice vs. liquid water. The methane storage capacity via hydrate formation increases with an increase in the pore size up to an optimum value for the 25 nm pore size model-carbon, with a 173% improvement in the adsorption capacity as compared to the dry sample. Synchrotron X-ray powder diffraction measurements (SXRPD) confirm the formation of methane hydrates with a sI structure, in close agreement with natural hydrates. Furthermore, SXRPD data anticipate a certain contraction of the unit cell parameter for methane hydrates grown in small pores.

H2S peut être un gaz dominant dans les réservoirs pétroliers carbonatés. Cependant, les recherches sur l'influence de H2S sur la composition et la stabilité thermique du pétrole restent limitées. Dans cette thèse, les interactions entre les hydrocarbures et H2S ont été étudiées de 310 à 350°C, à 700 bar, par pyrolyse confinée en tubes d'or scellés. La pyrolyse d'une huile non soufrée en présence de H2S ont permis de mettre en évidence une nouvelle voie de formation des composés organiques soufrés dans les pétroles. Les pyrolyses des mélanges n-octane/H2S et alkylbenzène/H2S ont permis de proposer les différentes réactions radicalaires pour la formation des produits soufrés principaux : les thiophène, thiols, thiacycloalcanes, alkyl-thiophènes dans le premier cas ; les thiols aromatiques, alkyl-benzothiophènes dans le second. Les résultats obtenus dans le mélange n-octane/H2S ont permis d'établir et valider un modèle cinétique détaillé. Ce mécanisme a permis de montrer que la pyrolyse n-octane/H2S se déroule en chaînes longues et que H2S a un effet inhibiteur sur la consommation du n-octane aux températures supérieures à 320°C, mais accélère fortement la réaction aux basses températures. Des extrapolations du modèle aux conditions géologiques (150-200°C, 700 bar) montrent que H2S a un effet important sur la composition chimique et la stabilité thermique des hydrocarbures. Le modèle permet aussi d'explorer la réactivité de H2S aux conditions de récupération assistée d'huiles lourdes soufrées (injection vapeur, pyrolyse) ou aux conditions de stockages en réservoir pétroliers déplétés
H2S can be a dominant gas in carbonate petroleum reservoirs. However, researches on the influence of H2S on the oil stability are limited in literature. In this thesis, interactions between hydrocarbons (oils, model compounds) and H2S were studied by confined pyrolysis in gold cells from 310 to 350°C under 700 bar. Results of pyrolysis of oil (free of sulfur) in presence of H2S lead to highlight a new pathway of formation of organic sulfur compounds in oils. Pyrolysis of binary mixtures n-octane/H2S and alkylbenzène/H2S allowed to propose different radical reactions for the generation of main sulfur products, namely, thiophene, thiols, thiacycloalkanes, alkyl-thiophenes in the first case ; thiol-aromatics, alkyl-benzothiophenes in the second. Results obtained in the mixture n-octane/H2S led to construct and validate a detailed mechanistic model. The mechanism shows that pyrolysis of n-octane/H2S occurs in long chain and H2S has an inhibition effect on the consumption of n-octane at temperatures above of 320°C, but accelerate the reaction rate strongly at low temperatures. Extrapolation of the kinetic model to geological temperatures and pressures (150-200°C, 700 bar) shows that H2S can significantly influence the composition and stability of hydrocarbons. It is also proposed to apply the model to study the reactivity of H2S under conditions of enhanced recovery (steam injection, pyrolysis) or of geological storage in depleted petroleum reservoirs

Les alliages à base de Nickel constituent les meilleurs matériaux actuellement développés pour répondre aux sollicitations sous hautes températures dans les domaines de l’aéronautique du nucléaire etc… L’objectif de ce travail de thèse est d’étudier leur comportement en température sous sollicitations de fretting usure. Dans cette étude, on s’intéresse à un contact René125/Waspaloy représentatif d’une application aéronautique. Dans un premier temps nous avons étudié l’effet de la température. On montre qu’à partir de 400°C, l’interface génère la formation d’une glaze layer lubrifiante qui réduit considérablement la cinétique de l’usure. En fixant la température à 700°C (température de l’application industrielle), nous avons étudié la stabilité de ces couches protectrices vis-à-vis de la pression de contact, de l’amplitude de glissement, de la fréquence et du nombre de cycle appliqués. Cette analyse montre une évolution bilinéaire de l’usure avec une usure initiale rapide liée à la formation de la « glaze layer » puis une usure additionnelle quasiment nulle dès que la « glaze layer » est formée. Ces travaux montrent que le volume d’usure associée à la formation de la « glaze layer » est fonction de la vitesse de glissement. Au dessus d’une vitesse seuil de glissement, la formation de la « glaze layer » protectrice devient plus difficile. Une courbe maîtresse est ainsi établie. Des analyses chimiques des interfaces associées à des essais interrompus ont permis d’établir le scénario de formation de ces glaze layers. Pour finir, une étude comparative des revêtements développés dans le cadre du projet INNOLUB a été menée de façon à sélectionner le revêtement offrant les meilleures propriétés tribologiques pour l’application étudiée
Nickel based alloys are the most developed materials nowadays for applications at high temperature, as in aeronautics, nuclear…The aim of this study is to understand their behavior at high temperature under fretting wear solicitations. Thereby, we had focused on a tribosystem formed of Waspaloy/René 125, which represent the crankcase/blade contact of the low pressure Turbine. We started studying the temperature effect, it is been noticed that above T = 400°C, a lubricant tribofilm, called the Glaze Layer is generated at the interface of the contact, which enable an abrupt reduction in friction and wear rate. The temperature was than fixed at 700°C (service temperature), so the glaze layer stability was analyzed as a function of contact pressure, sliding amplitude, frequency and number of cycles imposed. This analysis shows a bilinear wear evolution, characterized by a fast initial wear related to the formation of the glaze layer, followed by almost no wear once the glaze layer is formed. This study showed that the wear rate related to the glaze layer formation is dependent of the sliding velocity. Above a sliding velocity threshold, the formation of a stabilized glaze layer is quite difficult. A Master curve is here established. Microscopic and spectroscopic investigations are conducted to analyze the interface based on interrupted tests of a very short duration. Leading to a precise description of the glaze layer formation mechanisms. At the end of this study, a comparative analysis of different coatings developed to improve these components behavior, in the framework of INNOLUB project was established, allowing choosing the coating offering the best tribological properties and lifetime

Le monoxyde d’azote (NO) est un polluant atmosphérique responsable d’effets nuisibles sur l’environnement et la santé. Afin de mieux contrôler ces émissions, il est indispensable de comprendre et de maîtriser leur formation,en particulier lors de la combustion à haute pression, domaine d’application industrielle (cas des turbines à gaz,des moteurs…). On distingue quatre voies principales de formation de NO : la voie thermique, la voie du NO précoce, la voie NNH et la voie N2O. L’objectif de cette thèse à caractère expérimentale est de compléter la base de données expérimentale déjà existante nécessaire à la compréhension et à l’identification de la contribution de chaque voie à la formation du NO à haute pression.Dans cette thèse, un dispositif de brûleurs à contre-courants a été utilisé pour étudier la structure de flammes laminaires, prémélangées à haute pression. Les profils de concentration de NO dans les flammes CH4/O2/N2 à différentes richesses (Фc =0,7-1,2) et différentes pressions (P=0,1-0,7 MPa) ont été mesurés par Fluorescence Induite par Laser. L’effet de l’ajout d’hydrogène (80%CH4/20%H2 : Application Hythane®) sur la formation de NO a également été étudié dans les flammes pauvres CH4/O2/N2. Le mécanisme cinétique GDF-Kin®3.0_NCN a été comparé aux mesures de NO disponibles dans la littérature ainsi qu’aux simulations des mécanismes cinétiques du Gaz Research Institute (version 2.11 et 3.0). Ces trois mécanismes ont été ensuite comparés aux mesures expérimentales réalisées dans ces travaux de thèse
The nitric oxide (NO) is a pollutant responsible of detrimental effects on the environment and health. To better control these emissions, it’s crucial to understand and to control their formation, in particular during the combustion process at high pressure, area of industrial applications (gas turbines, engines…).There are four major routes of the NO formation: the thermal route, the prompt-NO route, the NNH route and theN2O route. The aim of this experimental thesis is to complete the existing experimental database which isnecessary to the understanding and the identification of the contribution from each route to the NO formation at high pressure.In this thesis, a facility of two twin counter-flow burners was used to study the structure of the laminar, premixed flames at high pressure. Experimental NO concentration profiles have been measured in CH4/O2/N2 flames for arange of equivalence ratio (from 0.7 to 1.2) and pressures (from 0.1 to 0.7 MPa) by Laser Induced Fluorescence.The effect of adding hydrogen (80%CH4/20%H2: Hythane® application) on the NO formation has been also studied in lean CH4/O2/N2 flames. The GDF-Kin®3.0_NCN kinetic mechanism has been compared to experimental data from the literature and also compared to the simulations from the Gas Research Institute mechanisms (version 2.11 and 3.0). These three mechanisms have been finally compared to the experimental data from this thesis

L’objectif de cette thèse doctorale fut la synthèse de composés polyazotés qui serviraient comme matériaux énergétiques du futur. Afin d’y arriver, les propriétés physico-chimiques de l’azote pur ainsi que des mélanges binaires xénon-azote, hydrogène-azote ainsi que lithium-azote furent étudiés à des pressions et températures extrêmes. Lors de la compression de l’azote pur jusqu’à environ 250 GPa et chauffé à 3300 K, une nouvelle forme d’azote polymérique constituée d’anneaux N6 interconnectés fut obtenue. À basse pression, les études du mélange Xe-N2 permirent de découvrir un composé de van der Waals de stoechiométrie Xe(N2)2. À plus haute pression et température (150 GPa et 2500 K) un solide composé de xénon et d’azote simplement lié fut obtenu. L’étude du système N2-H2 se focalisa sur le composé N2(H2)2. Sa structure complexe fut déterminée et, une réaction chimique vers 50 GPa ayant comme produit de réaction des azanes (NxHx+2) fut mise à jour. Il fut constaté que l’azane ammoniac (NH3), principalement obtenu, se transforme en hydrazine (N2H4)—pourtant a priori moins stable thermodynamiquement—lors de la décompression des échantillons réagit. Enfin, l’étude du système Li-N2 révéla une chimie remarquable entre ces deux éléments. Une grande variété d’anions d’azote fut obtenue, notamment N3-, [N2]~2 [N2]~1 et N5-. En particulier, le pentazolate de lithium (LiN5), contenant l’anion pentazolate hautement énergétique, put être récupéré aux conditions ambiantes. Ce composé est le premier composé polyazoté à haute densité d’énergie produit par pression et récupéré aux conditions ambiantes, démontré le potentiel des synthèses hautes pressions pour ce type de matériau
The goal of this thesis is to synthesize novel polynitrogen compounds by pressure as the next-generation high energy density materials (HEDM). To achieve this, the physico-chemical properties of pure nitrogen as well as the xenon-nitrogen, hydrogen-nitrogen and lithium-nitrogen mixtures were studied under extreme pressure and temperature conditions. In the case of the compression of pure nitrogen, a novel polymeric nitrogen solid composed of interconnected chains of N6 rings was produced at 250 GPa and 3300 K. The low pressure Xe-N2 investigation revealed the formation of a stoichiometric Xe(N2)2 van der Waals compound. Above 150 GPa and 2500 K a xenon-polynitrogen material was observed. The N2-H2 study, focusing on the characterization and high-density behavior of the N2(H2)2 van der Waals compound, uncovered its pressure-induced chemical reaction near 50 GPa into azanes (NxHx+2), with ammonia (NH3) as the main constituent. Intriguingly, decompression of the reacted sample resulted, below 10 GPa, in the transformation of ammonia into its thermodynamically less stable counterpart hydrazine (N2H4). Lastly, the Li-N2 system proved to be of great interest due to the large array of anionic nitrogen moieties discovered (N3-, [N2]~2 [N2]~1 and N5-). In particular, lithium pentazolate (LiN5), containing the elusive energetically-rich pentazolate anion, was synthesized above 45 GPa and 2500 K. Moreover, it could be retained down to ambient conditions. It is the first polynitrogen HEDM produced by high pressure and retrieved down to ambient conditions. These results demonstrate the potential of high pressure for the synthesis of industrially relevant HEDM

Fluid migration behind the cased holes is an important problem for oil and gas industry both considering short terms and long terms after cementing operation. For many reasons like high formation pressures, high shrinkage rate of cement slurry while setting, lack of mechanical seal, channeling due to cement slurry setting profile, hydrocarbon migration may occur and lead expensive recompletion operations and sometimes abandonment. Solutions to this problem vary including high density-low fluid loss cement slurry or right angle cement setting profile. During this study, the effect of &ldquo
free water&rdquo
which is the basic quality property of API G class cement, on fluid migration potential has been tested for different samples and in combination with different physical conditions. For this study API G class cements have been used. In order to justify the quality of each cement sample standard API G class quality tests were conducted. Moreover, as a main instrument &ldquo
Static Gel Strength Analyzer&rdquo
is used to measure the static gel strength of cement slurry and how long it takes to complete transition time. Bolu cement, Nuh cement, and Mix G cement samples were tested according to their free fluid values which are %2.5, %5, %3.12 respectively, and it is found that the Bolu cement with lowest free fluid content has the lowest potential for fluid migration. As a conclusion, fluid migration through behind the cased hole is a major threat for the life of the well. Appropriate cement slurry system may easily defeat this threat and lead cost saving well plans. Key words: Fluid migration, fluid loss, transition time, channeling, right angle, API G class cement, free water, high formation pressure

In der vorliegenden Arbeit wird das Konzept einer druckbasierten Analyse von Fest-Gas-Gleichgewichten hinsichtlich theoretischer wie experimenteller Zusammenhänge untersucht. Hierfür erfolgt eine gezielte Nutzung der Beziehungen von theoretischen und experimentell zugänglichen physikalischen Parametern, um so die Grundlage für eine spätere Anwendung im Kontext der Syntheseplanung zu ermöglichen. Im Speziellen handelt es sich im vorgestellten Konzept um die aus festkörperanalytischer Sicht häufig vernachlässigte Beziehung zwischen dem Dampfdruck von Festkörpern und dem chemischen Potenzial. Neben der theoretischen Erarbeitung des Analysekonzeptes befasst sich die vorgestellte Arbeit zusätzlich mit dessen experimenteller Umsetzung anhand der Entwicklung bzw. Optimierung der Analyseverfahren der Hochtemperatur-Gasphasenwaage sowie des automatisierten Membrannullmanometers. Abgeschlossen wird die Arbeit zudem durch die anschauliche Vorstellung der praktischen Anwendung des Konzeptes hinsichtlich unterschiedlicher Fragestellungen (Theorie vs. Experiment: Quecksilber/Phosphor/Iod, Analyse der Phasenbildung: Arsen/Phosphor, rationale Syntheseplanung: IrPTe, Syntheseoptimierung: Bi13P3I7, Kinetik: FeAs).

La formation du noyau sur Terre se produit par différenciation métal-silicate dans un océan magmatique. Ce processus d'équilibrage permet d'éliminer les éléments sidérophiles du manteau jusqu'au noyau, en fixant la composition en éléments traces des deux réservoirs. Des expériences de cloisonnement métal-silicate à haute pression et à haute température peuvent être utilisées pour faire correspondre les abondances observées et, comme le cloisonnement des éléments est fonction de P, T, fO2 et de la composition, elles limitent davantage les conditions thermochimiques de la formation du noyau. Dans cette thèse, des expériences de partitionnement métal-silicate superliquide des éléments sidérophiles et lithophiles (Ni, Cr, V, Nb, Ta et W) ont été réalisées dans des cellules d'enclumes de diamant chauffées au laser dans des conditions P-T jusqu'à 94 GPa et 4500K. Dans ces conditions P-T extrêmes, on constate que (1) aucun effet mesurable de la concentration de nickel sur le partage du Ni, du Cr et du V, l'alliage Fe-Ni est chimiquement idéal sur une large gamme de concentrations de Ni (3.5 à 48.7 % en poids) ; (2) Nb, Ta et W deviennent plus siderophile avec la température et en interaction avec l'oxygène du métal alors que Nb et W deviennent moins siderophile sous pression. En nous basant sur le paramétrage de nos résultats à haute teneur en P en fonction de P, T, fO2 et de la composition, nous avons modélisé une formation de noyaux à plusieurs stades et montré que le rapport Nb/Ta sous-chondritique dans le manteau peuvent s'expliquer soit en oxydant soit en réduisant les conditions de formation du noyau.Après le dernier événement de différenciation noyau-manteau, le noyau de la Terre est considéré comme fixé. On a récemment proposé que le SiO2 puisse se cristalliser à partir d'un alliage liquide de Fe-Si-O au sommet du noyau pendant le refroidissement séculaire, et flotter en raison de sa flottabilité négative, modifiant ainsi sa composition avec le temps. Nous avons étudié ici le champ liquidus des binaires Fe-Si, Fe-O et ternaires Fe-Si-O à la pression d'enveloppe du manteau du noyau et une gamme de températures en utilisant la dynamique moléculaire ab initio, englobant toutes les valeurs plausibles pour le noyau à travers le temps géologique. Nous constatons que les liquides restent bien mélangés avec des propriétés ternaires identiques au mélange de propriétés binaires. Des simulations en deux phases du SiO2 solide et du Fe liquide montrent une dissolution à des températures égales ou supérieures à 4100 K, ce qui suggère que la cristallisation du SiO2 ainsi que l'immiscibilité du liquide dans le Fe-Si-O sont peu probables dans le noyau terrestre
Core formation on Earth occurs by metal-silicate differentiation in a magma ocean. This equilibration process strips siderophile elements from the mantle to the core, setting the trace-element composition of both reservoirs. High-pressure and high-temperature metal-silicate partitioning experiments can be used to match the observed abundances, and because element partitioning is a function of P, T, fO2 and composition, further constrain the thermochemical conditions of core formation. In this thesis, superliquidus metal-silicate partitioning experiments of both siderophile and lithophile elements (Ni, Cr, V, Nb, Ta and W) have been performed in laser-heated diamond anvil cells at P-T conditions up to 94 GPa and 4500 K. At these extreme P-T conditions, it is found that (1) no measurable effect of nickel concentration on the partitioning of Ni, Cr and V, the Fe-Ni alloy is chemically ideal over a broad range of Ni concentrations (3.5 to 48.7 wt%); (2) Nb, Ta and W become more siderophile with temperature and by interacting with oxygen in the metal, whereas Nb and W become less siderophile with pressure. Based on the parameterization of our high-P results as a function of P, T, fO2 and composition, we have modelled a multi-stage core formation and shown that subchondritic Nb/Ta ratio in the mantle can be explained by either oxidizing or reducing core-forming conditions. After the last event of core-mantle differentiation, the Earth’s bulk core is considered frozen from then onwards. It was recently proposed that SiO2 could crystallize from a Fe-Si-O liquid alloy at the top of the core during secular cooling, and float out due to its negative buoyancy, hence changing core composition over time. Here we investigated the liquidus field of Fe-Si, Fe-O binaries and Fe-Si-O ternaries at core-mantle boundary pressure and a range of temperatures using ab initio molecular dynamics, encompassing any plausible values for the core through geological time. We find that the liquids remain well mixed with ternary properties identical to the mixing of binary properties. Two‐phase simulations of solid SiO2 and liquid Fe show dissolution at temperatures at and above 4100 K, suggesting that SiO2 crystallization as well as liquid immiscibility in Fe–Si–O is unlikely to occur in Earth's core

Soot is a carbon particulate formed as a result of the combustion of fossil fuels. Due to the health hazard posed by the carbon particulate, government agencies have applied strict regulations to control soot emissions from road vehicles, airplanes, and industrial plants. Thus, understanding soot formation and evolution is critical. Practical combustion devices operate at high pressure and in the turbulent regime. Elevated pressures and turbulence on soot formation significantly and fundamental understanding of these complex interactions is still poor. In this study, the effects of pressure and turbulence on soot formation and growth are investigated numerically. As the first step, the evolution of the particle size distribution function (PSDF) and soot particles morphology are investigated in turbulent non-premixed flames. A Direct Simulation Monte Carlo (DSMC) code is developed and used. The stochastic reactor describes the evolution of soot in fluid parcels following Lagrangian trajectories in a turbulent flow field. The trajectories are sampled from a Direct Numerical Simulation (DNS) of an n-heptane turbulent non-premixed flame. Although individual trajectories display strong bimodality as in laminar flames, the ensemble-average PSDF possesses only one mode and a broad tail, which implies significant polydispersity induced by turbulence. Secondly, the effect of the flow and mixing fields on soot formation at atmospheric and elevated pressures is investigated in coflow laminar diffusion flames. The experimental observation and the numerical prediction of the spatial distribution are in good agreement. Based on the common scaling methodology of the flames (keeping the Reynolds number constant), the scalar dissipation rate decreases as pressure increases, promoting the formation of PAH species and soot. The decrease of the scalar dissipation rate significantly contributes to soot formation occurring closer to the nozzle and outward on the flames wings as pressure increases. The scaling of the scalar dissipation rate is not straightforward due to buoyancy effects. Finally, a new scaling approach of the flame at different pressures is introduced. In this approach, both Reynolds number and Grashof number are kept constant so that the effect of gravity is the same at all pressures. In order to keep Gr constant, this requires the diameter of the nozzle to be changed as pressures vary. This approach guarantees a similar non-dimensional flow field at all pressures and rules out the effect of hydrodynamics and mixing, so that only the effect of chemical kinetics on soot formation can be studied.

Combustion of kerosene propellants often deposits soot on chamber walls. These deposits act as a thermal barrier and can significantly affect the analysis of cooling systems. This is especially vital for reusable engines since the accumulated soot deposit can make the wall heat flux vary between every firing. This dissertation discusses a computational and experimental effort to understand the main drivers of these soot deposits. The computational approach employs the Method of Moments with Interpolative Closure (MOMIC) model to predict soot particle dynamics; Brownian and thermophoretic diffusion for particle transport to the chamber surface; and the Hydrogen-Abstraction-Acetylene-Addition (HACA) mechanism for soot surface growth. These models were incorporated in a 1D plug flow reactor. Two-dimensional axisymmetric reacting CFD simulations were also run to understand the flow field influence on the near wall gas phase chemistry. Simultaneously, a fuel rich kerosene and gaseous oxygen experiment was developed and fired to obtain soot deposit thickness measurements for model comparison. The results show the reduced order plug flow model can satisfactorily predict the soot thickness and that thermophoresis is the dominant deposition mechanism. However, though the model can predict deposit mass trends, it underpredicts the absolute values for some conditions and may need an additional mechanism.

The first goal of this thesis is to validate a detailed co-flow flame soot formation model for high pressure applications. The second goal is to use this detailed model to understand the effect pressure has on soot formation. The third goal is to note any deficiencies in the model, and the fourth is to remedy these issues. The thesis is divided into two research studies. The first study validates the model for high pressure use against ethane-air co-flow diffusion flames from 2 to 15 atm. After validation, the results are used to determine the impact pressure has on the three main soot formation processes. It is determined that the original model could not account for the flame pre-heating effect. The second study addresses this issue by adapting the model to extend below the fuel tube exit plane, and includes conjugate heat transfer (CHT) between the fluid streams and solid fuel tube.

An experimental study was conducted using axisymmetric co-flow laminar diffusion flames of methane-air, methane-oxygen and ethylene-air to examine the effect of pressure on soot formation and the structure of the temperature field. A liquid fuel burner was designed and built to observe the sooting behavior of methanol-air and n-heptane-air laminar diffusion flames at elevated pressures up to 50 atm. A non-intrusive, line-of-sight spectral soot emission (SSE) diagnostic technique was used to determine the temperature and the soot volume fraction of methane-air flames up to 60 atm, methane-oxygen flames up to 90 atm and ethylene-air flames up to 35 atm. The physical flame structure of the methane-air and methane-oxygen diffusion flames were characterized over the pressure range of 10 to 100 atm and up to 35 atm for ethylene-air flames. The flame height, marked by the visible soot radiation emission, remained relatively constant for methane-air and ethylene-air flames over their respected pressure ranges, while the visible flame height for the methane-oxygen flames was reduced by over 50 % between 10 and 100 atm. During methane-air experiments, observations of anomalous occurrence of liquid material formation at 60 atm and above were recorded. The maximum conversion of the carbon in the fuel to soot exhibited a strong power-law dependence on pressure. At pressures 10 to 30 atm, the pressure exponent is approximately 0.73 for methane-air flames. At higher pressures, between 30 and 60 atm, the pressure exponent is approximately 0.33. The maximum fuel carbon conversion to soot is 12.6 % at 60 atm. For methane-oxygen flames, the pressure exponent is approximately 1.2 for pressures between 10 and 40 atm. At pressures between 50 and 70 atm, the pressure exponent is about -3.8 and approximately -12 for 70 to 90 atm. The maximum fuel carbon conversion to soot is 2 % at 40 atm. For ethylene-air flames, the pressure exponent is approximately 1.4 between 10 and 30 atm. The maximum carbon conversion to soot is approximately 6.5 % at 30 atm and remained constant at higher pressures.

Abstract: Soot from combustion emissions has a negative impact on human health and the environment. Understanding and controlling soot formation is desirable to reduce this negative impact, especially as energy demands continue to increase. In this work, a range of fundamental combustion experiments are performed to better understand the soot formation process, and to develop diagnostics for measuring soot properties. First, studies on the effects of doping the flame with different polycyclic aromatic hydrocarbons (PAHs) was performed to investigate soot nucleation mechanisms. Soot formation was found to be most sensitive to phenylacetylene addition and nucleation through physical dimerization appears to be unlikely. Next, the effects of ammonia addition, a possible future fuel, on soot formation in laminar nonpremixed ethylene counterflow flames was performed. A reduction in soot volume fraction was observed and attributed to chemical effects of ammonia addition. Second, the investigation and development of several types of diagnostics was performed. Soot is typically reported to scale with pressure as Pn where P is pressure and n is a scaling factor. A wide range of scaling factors for ethylene coflow flames have been reported using different types of diagnostics. In this work, a comparison between a light extinction technique and PLII was performed and differences between reported values was explored. Next, the time resolved laser induced incandescence (TiRe-LII) diagnostic was advanced by exploring the effects of SVF on local gas heating. Errors introduced into this model by neglecting local gas heating are explored. Finally, a new diagnostic was developed for 3 dimensional measurements of SVF and velocity in turbulent flames using a technique known as diffuse-backlight illumination extinction imaging. Third, the application of gated 2D TiRe-LII was assessed in pressurized environments on laminar coflow flames. Comparisons between TiRe-LII and thermophoretically captured soot imaged by transmission electron microscopy (TEM) was performed. TiRe-LII was found to have reasonable agreement with TEM measurements if the SNR was high, but due to the large disparity in primary particle size in pressurized environments errors in 2D TiRe-LII can be significant.

Laminar axisymmetric syngas-air, syngas-methane mixture-air and biogas-air diffusion fames were studied over the pressure range of 5 to 20 atm to investigate the effect of pressure and dilution on soot formation. Spectral soot emission (SSE) optical diagnostic technique was used to measure the soot volume fraction and soot temperature in these flames. The fuel matrix consisted of three syngas fuels, two syngas-methane mixtures and two biogas fuels. In general, soot formation in syngas-methane mixtures and biogas diffusion flames showed strong pressure dependence at lower pressures but this dependence got weaker at elevated pressures. No soot was detected by SSE diagnostic technique in syngas-air flames at all pressures. The suppressive effect of carbon dioxide on soot formation prevailed at all pressures in syngas-methane mixtures and biogas flames.

Fully understanding soot formation in flames is critical to the development of practical combustion devices, which typically operate at high pressures, and fire suppression systems in space. Flames display significant changes under microgravity and high-pressure conditions as compared to normal-gravity flames at atmospheric pressure, but the exact causes of these changes are not well-characterized. As such, the effects of gravity and pressure on the stability characteristics and sooting behavior of laminar coflow diffusion flames were investigated. To study these effects, a new highly-scalable combustion modelling tool was developed specifically for use on large multi-processor computer architectures. The tool is capable of capturing complex processes such as detailed chemistry, molecular transport, radiation, and soot formation/destruction in laminar diffusion flames. The proposed algorithm represents the current state of the art in combustion modelling, making use of a second-order accurate finite-volume scheme and a parallel adaptive mesh refinement algorithm on body-fitted, multi-block meshes. An acetylene-based, semi-empirical model was used to predict the nucleation, growth, and oxidation of soot particles. Reasonable agreement with experimental measurements for different fuels and pressures was obtained for predictions of flame height, temperature and soot volume fraction. Overall, the algorithm displayed excellent strong scaling performance by achieving a parallel efficiency of 70% on 384 processors. The effects of pressure and gravity were studied for flames of two different fuels: ethylene-air flames between pressures of 0.5–5 atm and methane-air flames between 1–60 atm. Based on the numerical predictions, zero-gravity flames had lower temperatures, broader soot-containing zones, and higher soot concentrations than normal-gravity flames at the same pressure. Buoyant forces caused the normal-gravity flames to narrow with increasing pressure while the increased soot concentrations and radiation at high pressures lengthened the zero-gravity flames. Low-pressure flames at both gravity levels exhibited a similar power-law dependence of the maximum carbon conversion on pressure which weakened as pressure was increased. This dependence decayed at a faster rate in zero gravity when pressure was increased beyond 1–10 atm.

Accurate determination of soot emissions from combustion is of interest in both fundamental research and industries that rely on combustion. Laser-induced incandescence of soot particles is a young technique that allows unobtrusive measurements of both soot volume fraction and particulate size. An apparatus utilizing this technique has been brought to function for both atmospheric and high pressure measurements. Proof of concept measurements of an atmospheric ethylene-air laminar diffusion flame at 35, 42, and 47 mm above the burner exit correlate well with literature findings. Profile trends of a methane-air diffusion flame at 10, 20, and 40 atm at 6 mm above the burner are similar to reports in literature and are compared to trends from spectral soot emission measurements. Particle size is found to be roughly proportional to pressure. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus are herein.

Measurements of soot emission properties are of interest in both fundamental research and combustion-based industries. Laser-induced incandescence of soot particles is a novel technique that allows unobtrusive measurements of both soot volume fraction and particulate size with significant advantages. An apparatus utilizing this technique has been customized and used to provide measurements of soot concentration and particle sizing of a laminar, diffusion methane/air flame at pressures of 10, 20 and 40 atm at 6~mm above the burner. Soot volume fraction measurements correlate well with literature findings at all pressures. Despite similar trends, particle size values are found to be consistently larger than values reported in literature. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus and results are herein.

Methane-air, ethane-air, and n-heptane-air over-ventilated co-flow laminar diffusion flames were studied up to pressures of 2.03, 1.52, and 0.51 MPa, respectively, to determine the effect of pressure on flame shape, soot concentration, and temperature. A spectral soot emission optical diagnostic method was used to obtain the spatially resolved soot formation and temperature data. In all cases, soot formation was enhanced by pressure, but the pressure sensitivity decreased as pressure was increased. The maximum fuel carbon conversion to soot, ηmax, was approximated by a power law dependence with the pressure exponent of 0.92 between 0.51 and 1.01 MPa, and 0.68 between 1.01 and 2.03 MPa with ηmax=9.5% at 2.03 MPa for methane-air flames. For ethane-air flames, the pressure exponent was 1.57 between 0.20 and 0.51 MPa, 1.08 between 0.51 and 1.01 MPa, and 0.58 between 1.01 and 1.52 MPa where ηmax=23% at 1.52 MPa. For nitrogen-diluted n-heptane-air flames, ηmax=6.5% at 0.51 MPa.

碩士
國立交通大學
機械工程系所
92
In Articular cartilage, chondrocytes are embedded in an extracellular matrix composed of water, soluble constituents, and insoluble polymers. The physical stimulation of hydrostatic pressure is known to influence the development, maturation, and degeneration of cartilage. Previous animal and tissue explant studies have shown that time-varying dynamic tissue loading can increase the synthesis and deposition of matrix molecules in an amplitude, frequency, duration ands three-dimensional culture. In this study, a novel hydrostatic pressure bioreactor system was designed for culture partially digested cartilage tissue fragments. In conventional culture preparation, a tissue piece is cut in a culture dish by scalpel blade, soaked in protease enzyme to separate cells from cytoplasm, and applied to a culture experiment. When cut by scalpel blade, however, the tissue piece is easily polluted and difficult to collect. The present invention successively cuts, filters, and collects finally the homogenized tissue pieces in a sealed device. As well, because the present invention homogenizes the tissue piece by cutting, histiocytes are undamaged and can be applied in live histiocyte culture. Our result demonstrate that this hydrostatic bioreactor system enables chondrocytes under hydrostatic pressure after 2 weeks to grow and secrete extracelluar matrix comprised GAGs and type II collagen steadily. In summary , the morphologies of many cells stimulated by hydrostatic pressure were similar to the chondrocytes in normal cartilage.

In der vorliegenden Arbeit wird das Konzept einer druckbasierten Analyse von Fest-Gas-Gleichgewichten hinsichtlich theoretischer wie experimenteller Zusammenhänge untersucht. Hierfür erfolgt eine gezielte Nutzung der Beziehungen von theoretischen und experimentell zugänglichen physikalischen Parametern, um so die Grundlage für eine spätere Anwendung im Kontext der Syntheseplanung zu ermöglichen. Im Speziellen handelt es sich im vorgestellten Konzept um die aus festkörperanalytischer Sicht häufig vernachlässigte Beziehung zwischen dem Dampfdruck von Festkörpern und dem chemischen Potenzial. Neben der theoretischen Erarbeitung des Analysekonzeptes befasst sich die vorgestellte Arbeit zusätzlich mit dessen experimenteller Umsetzung anhand der Entwicklung bzw. Optimierung der Analyseverfahren der Hochtemperatur-Gasphasenwaage sowie des automatisierten Membrannullmanometers. Abgeschlossen wird die Arbeit zudem durch die anschauliche Vorstellung der praktischen Anwendung des Konzeptes hinsichtlich unterschiedlicher Fragestellungen (Theorie vs. Experiment: Quecksilber/Phosphor/Iod, Analyse der Phasenbildung: Arsen/Phosphor, rationale Syntheseplanung: IrPTe, Syntheseoptimierung: Bi13P3I7, Kinetik: FeAs).

Dissertação de mestrado em Bioengenharia
Human neutrophil elastase, as inflammatory response, has the capacity to degrade collagen and elastin component of extracellular matrix, being extensively involved in wrinkles formation induced by UV radiation damage. In order to develop a cosmetic antiwrinkling emulsion, we incorporated a potent synthetic HNE inhibitor, sivelestat (IC50 = 44 nM, Ki = 0.2 μM), into biopolymeric nanoparticles prepared by high-energy emulsification methods. As nanomaterial was used Bombyx mori silk fibroin protein, an FDA approved natural biocompatible and biodegradable polymer. Silk fibroin nanoparticles (SF-NPs) were produced by two high-energy emulsification methods, ultrasonication and high pressure homogenization (HPH), in oil-in-water (o/w) emulsions using as n-dodecane as oil phase. According to optimized results, best formulations were obtained for 10 g/L of SF at 20/80 of o/w ratio at 22 cycles of homogenization by double-stage HPH (APV-2000™). During the NPs production by HPH emulsification process, the secondary SF structure changed from random-coil conformation to a more stable structure, β -sheets. Stabilizers effect was also studied, namely poloxamer 407, transcutol, tween 80 and sodium dodecyl sulfate (SDS), in which the results suggested that combination of transcutol and SDS would effectively stabilize the SF-NPs over time. To predict the sivelestat incorporation, orange IV was used as a model-drug, being this incorporated into SF-NPs at different concentrations. Release studies of orange IV were evaluated in absence and presence of 0.5 U/mL of HNE. The release of orange IV at 100 μM from SF-NPs (concentration considered as optimal) showed to be controlled at some extent, in which the drug transport mechanism showed to be anomalous (Fickian diffusion and polymer degradation/relaxation) and not affected by 0.5 U/mL of HNE enzyme. Finally, the incorporation of 100 μM of sivelestat in SF-NPs performed with a formation and encapsulation efficiency of 99% and 50%, respectively, successfully inhibited the HNE enzyme, enhancing the potential of this drug delivery system for topical antiwrinkling application.
Elastase de Neutrófilos Humana, como resposta inflamatória, possui a capacidade de degradar os componentes da matriz extracelular, nomeadamente colagénio e elastina, estando envolvida na formação de rugas causadas pela radiação ultravioleta. De forma a desenvolver uma emulsão cosmética antirrugas, decidiu-se incorporar um potente inibidor sintético de elastase, sivelestat (IC50 = 44 nM, Ki = 0,2 μM), em nanopartículas biopoliméricas formadas por métodos de emulsificação de elevada energia. Como nanomaterial usou-se a proteína fibroína de seda extraída do bicho-da-seda Bombyx mori, que é um polímero natural biocompatível e biodegradável aprovado pela FDA. As nanopartículas de fibroína de seda foram produzidas por dois métodos de emulsificação, ultrasonicação e homogeneização de elevada pressão, com emulsões óleo-em-água, tendo-se usado n-dodecano como fase oleosa. De acordo com os resultados otimizados, a melhor formulação foi obtida com 10 g/L de fibroína de seda numa razão óleo/água de 20/80 a 22 ciclos de homogeneização, através do método de duplo-sistema de homogeneização de elevada pressão (APV-2000™). Nestas condições, durante a produção de nanopartículas nestas condições, a estrutura secundária aleatória da proteína de fibroína de seda sofreu uma alteração conformacional para uma estrutura mais estável, em folhas βeta. O efeito de estabilizadores na nanoemulsão foi também estudado, nomeadamente poloxamer 407, transcutol, tween 80 e dodecil sulfato de sódio, em que os resultados obtidos sugerem que a combinação de transcutol e dodecil sulfato de sódio estabilizaria eficientemente as nanopartículas de fibroína de seda ao longo do tempo. Para prever a incorporação de sivelestat, o corante orange IV foi utilizado como composto modelo, tendo sido incorporado nas nanopartículas de fibroína de seda a várias concentrações, e tendo-se estudado a sua libertação na ausência e na presença de elastase (0,5 U/mL). A libertação de orange IV das nanopartículas de fibroína de seda, numa concentração de 100 μM (concentração otimizada), exibiu um mecanismo de transporte controlado, tendo este sido definido como anómalo (difusão de Fickian e degradação/relaxamento do polímero) e não mostrou ser influenciada pela elastase (0,5 U/mL). Finalmente, incorporação de 100 μM de sivelestat nas nanopartículas de fibroína de seda que indicou uma eficiência de formação e de encapsulação de 99% e 50%, respetivamente, inibiu a enzima elastase de forma eficaz, evidenciando o potencial deste nanosistema como cosmético antirrugas para aplicação transdérmica.