Benefited from the efficiency of hydraulic fracturing and horizon drilling, the production of unconventional oil and gas resources, such as shale gas and tight oil, has grown quickly in 21th century and contributed to the North America oil and gas production. Although the new enhancing oil recover (EOR) technologies and strong demand spike the production of unconventional resources, there are still unknowns in recovery mechanisms and phase behavior in tight rock reservoirs. In such environment, the phase behavior is altered by high capillary pressure owing to the nanoscale pore throats of shale rocks and it may also influence minimum miscibility pressure (MMP), which is an important parameter controlling gas floods for CO2 injection EOR. To investigate this influence, flash calculation is modified with considering capillary pressure and this work implements three different method to calculate MMP: method of characteristics (MOC); multiple mixing cell (MMC); and slim-tube simulation. The results show that CO2 minimum miscibility pressure in nanopore size reservoirs are affected by gas-oil capillary pressure owing to the alternation of key tie lines in displacement. The values of CO2-MMP from three different methods match well. Moreover, in tight rock reservoirs, the heterogeneous pore size distribution, such as the ones seen in fractured reservoirs, may affect the recovery mechanisms and MMP. This work also investigates the effect of pore size heterogeneity on multicomponent multiphase hydrocarbon fluid composition distribution and its subsequent influence on mass transfer through shale nanopores. According to the simulation results, compositional gradient forms in heterogeneous nanopores of tight reservoirs because oil and gas phase compositions depend on the pore size. Considering that permeability is small in tight rocks and shales, we expect that mass transfer within heterogeneous pore size porous media to be diffusion-dominated. Our results imply that there can be a selective matrix-fracture component mass transfer during both primary production and gas injection secondary recovery in fractured shale rocks. Therefore, molecular diffusion should not be neglected from mass transfer equations for simulations of gas injection EOR or primary recovery of heterogeneous shale reservoirs with pore size distribution. / Master of Science / The new technologies to recover unconventional resources in oil and gas industry, such as fracturing and horizontal drilling, boosted the production of shale gas and tight oil in 21st century and contributed to the North America oil and gas production. Although the new technologies and strong demand spiked the production of tight oil resources, there are still unknowns of oil and gas flow mechanisms in tight rock reservoirs. As we know, the oil and gas resources are stored in the pores of reservoir formation rock. During production process, the oil and gas are pushed into production wells by formation pressure. However, the pore radius of shale rock is extremely small (around nanometers), which reduces the flow rate of oil and gas and raises capillary pressure in pores. The high capillary pressure will alter the oil and gas phase behavior and it may influence the value of minimum miscibility pressure (MMP), which is an important design parameter for CO2 injection (an important technology to raise production). To investigate this influence, we changed classical model with considering capillary pressure and this modified model is implemented in different methods to calculate MMP. The results show that CO2 -MMP in shale reservoirs are affected by capillary pressure and the results from different methods match well. Moreover, in tight rock reservoirs, the heterogeneous pore size distribution, such as fractures in reservoirs, may affect the flow of oil and gas and MMP value. So, this work also investigates the effect of pore size heterogeneity on oil and gas flow mechanisms. According to the simulation results, compositional gradient forms in heterogeneous nanopores of tight reservoirs and this gradient will cause diffusion which will dominate the other fluid flow mechanisms. Therefore, we always need to consider molecular diffusion in the simulation model for shale reservoirs.

La membrane plasmique constitue la première entité séparant la cellule de son environnement. A ce rôle de barrière s'ajoute celui de réguler la. Par conséquent, la membrane plasmique est une zone privilégiée pour le passage d'information. Cependant, son étude reste difficile, ne serait-ce que par l'extraordinaire complexité d'organisation de cet assemblage supramoléculaire.Mon projet de thèse vise à développer de nouvelles approches expérimentales pour explorer plus spécifiquement l'organisation et le rôle de la membrane plasmique d'une cellule dans les mécanismes de transduction de l'information. Deux axes ont été privilégiés : le premier, concerne la description de la dynamique d'organisation de la membrane ; le deuxième concerne l'inter-connectivité et la transmission du signal d'une cellule avec d'autres partenaires.Ce manuscrit se compose de plusieurs parties. Le premier chapitre introduira succinctement les questions biologiques. Dans le second chapitre, je présenterai des méthodes utilisées pour l'étude de la membrane. J'y présenterai aussi une série d'observation que j'ai réalisée sur la diffusion de l'EGFR. Le troisième chapitre sera consacré à la technique de corrélation croisée de fluorescence depuis le montage jusqu'à l'étude du modèle EGFR. Dans la quatrième partie, nous verrons comment les collaborations à l'interface biophysique ont permis des développements innovants sur un système de pinces optiques holographiques. J'y présenterai les applications de ce système à différent modèles d'intérêt biologique. Enfin, je conclurai ce document par une brève discussion autour des résultats obtenus aussi bien d'un point de vue méthodologique que biologique. / The plasma membrane separates the cell from its environment. But it is more than a barrier any cell has to communicate with the outside world. Therefore the plasma membrane plays a prime role in transferring and exchanging information. However, the biological study of the plasma membrane remains difficult due to the extraordinary complexity of it organization.My thesis is a part of an effort to develop new experimental approaches to explore more specifically the organization and the role of the plasma membrane in the signal transduction mechanisms. Two major aspects were followed: the first one concerns the description of the dynamics of membrane organization and of molecular interactions, the second concerns the inter-connectivity and signal transduction between a cell and other biological partners.This manuscript is composed of several parts. The first chapter briefly introduces the biological questions that I tried to answer. In the second chapter, I present the methods commonly used to study the membrane with a dynamic perspective. Additionally, I include a series of observations that I made on the EGF receptor diffusion. The third chapter is devoted to the fluorescence cross-correlation technique to study the assembly of the EGFR. In the fourth part, I demonstrate how scientific collaborations at the interface between biology and physics have led to the development of innovative solutions on a holographic optical tweezers system. I present applications of this system in different biological models. Finally, I conclude this thesis with a brief discussion about my technological and biological results.

É crescente a demanda por materiais que atendam as exigências para construção de barreiras selantes (liners) em obras para disposição de resíduos. A utilização de solos tropicais para esta finalidade só não é maior por falta de conhecimento sobre muitas de suas características técnicas, principalmente a migração de contaminantes. Tentativas de melhoria das qualidades de solos supostamente inadequados também são importantes. Esta tese apresenta estudos sobre a migração dos íons \'CD POT.2+\', \'K POT.+\', \'CL POT.1-\' e \'F POT.-\' em latossolos residuais das formações Botucatu e Serra Geral e três diferentes misturas destes solos, com ênfase nos processos de sorção e difusão molecular. O potencial de retenção dos íons é avaliado através da construção de 33 isotermas de sorção resultantes de ensaios de equilíbrio em lote. Seus parâmetros são obtidos da adequação dos modelos linear, Freundlich e Langmuir as isotermas. O potencial de transporte dos íons é avaliado através de ensaios de difusão em colunas estanques, onde curvas teóricas produzidas no programa POLLUTE são ajustadas aos dados de concentração para a estimativa dos parâmetros de difusão. Os resultados dos estudos de retenção mostram que o \'CL POT.-\' experimenta sorção sob certas condições, o \'K POT.+\' e \'F POT.-\' possuem taxas semelhantes de retenção, e que a sorção do \'CD POT.2+\' se mostrou altamente dependente da composição da solução contaminante. Os ensaios de difusão resultaram em vários valores para o coeficiente de difusão efetiva (D*), mostrando que o fluxo difusivo dos íons diminui para solos mais argilosos. / There is a growing demand for materials that can be used in lining systems for waste disposal facilities. The use of tropical soils for this purpose is restricted due to the lack of technical knowledge about this type of material. Attempts to improve the quality of supposed unsuitable soils play also an important role. This thesis presents studies concerning the migration of the ions \'CD POT.2+\', \'K POT.+\', \'CL POT.-\' and \'F POT.-\' in latosoils from the Botucatu and Serra Geral formations and three different mixtures of these soils, with emphasis on sorption and molecular diffusion. Batch equilibrium tests were conduced to examine the retention capacity of the soils, and the sorption parameters are estimated by fitting the linear, Freundlich and Langmuir models to the experimental isotherm plots. The potential for these soils to transport ions is evaluated by diffusion tests, where theoretical curves produced in the POLLUTE code are used to estimate the effective diffusion coefficients (D*). The results show that the \'CL POT.-\' is sorbed under specific conditions and, therefore, it can not always be used as a conservative ion (i.e. nonreactive ion), \'K POT.+\' and \'F POT.-\' are sorbed in similar amounts, and that the \'CD POT.2+\' sorption is highly dependent on the contaminant solution composition. Several D* values are reported, showing that the diffusion rates are decreased for soils with more clay.

Nous étudions les comportements dynamiques de solutions aqueuses de dioxyde de carbone, pures ou sous forme de boissons gazeuses. Nous observons les façons dont des solutions carbonatées, initialement à l'équilibre de Henry, répondent à une perturbation, qui peut être un changement brusque de pression ou une agitation mécanique. Ces questions sont examinées expérimentalement, à l'aide de dispositifs construits pour cette étude. Ceux ci permettent de visualiser les champs de vitesse et les fronts de dissolution dans le fluide, dans des conditions variées de pression, taille et forme de système. Une partie importante est consacrée à la chemi-convection provoquée par la déstabilisation d'une couche diffuse de CO2 dissout. Nous présentons une caractérisation complète du phénomène, et une interprétation basée sur une théorie de l'instabilité de Rayleigh-Taylor correspondante. L'autre partie de notre travail concerne des systèmes fermés, dont la bouteille de champagne est l'exemple type. Nous montrons que l'agitation de la bouteille provoque une légère baisse transitoire de la pression interne, et expliquons le phénomène à l'aide d'un modèle basé sur la théorie d'Epstein-Plesset de la dynamique des bulles. / This work is about dynamical phenomena of water-carbon dioxide solutions, either pure binary mixtures or carbonated beverages. We address the general problem of how such solutions, initially at Henry's equilibrium, respond to a perturbation. The latter may be a sudden change in pressure, or mechanical shaking. These problems are investigated with the help of especially designed experimental hardware that allows us to visualize the velocity field and the concentration front inside solutions, in diverse conditions of pressure, system size and shape. An important part of the work is dedicated to chemi-convection, i.e. the fluid motion induced by destabilisation of the diffuse layer of dissolved CO2. Both experimental characterization and interpretation through a theory of the corresponding Rayleigh-Taylor instability are presented. The other part of the work is related to closed systems, representative of a bottle of champagne and of sodas in general. A key observation is that shaking produces a small transient drop of the internal pressure, which we explain through a dedicated modelbuilt on Epstein-Plesset's theory of bubble dynamics.

[pt] Parafinas de alto peso molecular presentes no petróleo escoando em ambientes de baixa temperatura cristalizam-se e depositam-se nas paredes internas dos dutos, ocasionando a redução da taxa de escoamento e o aumento do custo de produção, podendo levar até mesmo ao bloqueio das linhas de transporte. O processo de deposição é complexo e envolve conhecimento multidisciplinar, de modo que diferentes abordagens têm sido propostas para a sua modelagem. O principal objetivo deste trabalho foi investigar o fenômeno de deposição de parafina em uma geometria simples, com condições bem controladas, utilizando uma abordagem numérica e experimental, com foco no melhor entendimento dos mecanismos que induzem a deposição, a formação dos depósitos e seu envelhecimento. Experimentalmente, foram conduzidos testes com fluidos de laboratório que permitiam a visualização e a medição da evolução espacial e temporal de depósitos de parafina formados sob escoamentos laminar e turbulento. Numericamente, foi desenvolvido um modelo multicomponente para escoamento laminar, chamado de entalpia-porosidade. Tanto a espessura quanto a composição do depósito foram determinadas através de um modelo termodinâmico acoplado às equações de conservação de massa, de quantidade de movimento linear, de energia e de espécies. Os resultados indicaram que o efeito Soret não influencia a deposição de parafina. A espessura do depósito foi bem avaliada numericamente para regime permanente, apresentando diferenças na sua evolução temporal. O modelo composicional desenvolvido fornece importantes dados além da espessura depositada, como a temperatura inicial de aparecimento de cristais (TIAC) e o número de carbono crítico (NCC) do sistema, ampliando a previsão do processo de deposição com informações sobre a composição e o envelhecimento do depósito. As investigações numéricas mostraram que maiores taxas de cisalhamento e temperaturas da parede resultam em depósitos menos espessos. Mostrou-se também que maiores taxas de cisalhamento resultam em depósitos mais densos, e que maiores temperaturas da parede tendem a aumentar a saturação de sólido na região intermediária do depósito. / [en] High molecular weight paraffins crystallize and deposit on the inner walls of production lines and oil pipelines operating in cold environments, causing reductions in flow rate, increase of the production cost, or even the total blockage of the transport lines. Wax deposition is a complex process involving multidisciplinary knowledge, so that different approaches have been proposed for its modeling. The primary purpose of this work was to investigate the wax deposition process in a simple geometry under well-controlled conditions, using a numerical and experimental approach, focusing on a better understanding of the phenomena controlling the wax deposition, the formation of the deposit and its aging. Controlled experiments were conducted using laboratory solutions which allowed visualization and measurement of the spatial and temporal evolution of wax deposits under laminar and turbulent flows. A multicomponent model for laminar flow, called enthalpy-porosity, was developed. The thickness and composition of the deposit were determined by a thermodynamic model coupled with conservation equations of mass, linear momentum, energy and species. The results indicated that the Soret effect does not contribute to wax deposition. The thickness of the deposit was well predicted by the numerical model for steady state, presenting, however, differences in its temporal evolution. The multicomponent model developed provides valuable information in addition to the deposited thickness, such as the wax appearance temperature (WAT) and the critical carbon number (CCN) of the wax-oil system. These are relevant information for the prediction of the deposit composition and the aging process. The numerical results demonstrated that higher flow rates and wall temperatures lead to thinner deposits. It was also shown that the deposit wax content is higher for higher shear rates, while higher wall temperatures lead to higher solid content in the intermediate region of the deposit.

É crescente a demanda por materiais que atendam as exigências para construção de barreiras selantes (liners) em obras para disposição de resíduos. A utilização de solos tropicais para esta finalidade só não é maior por falta de conhecimento sobre muitas de suas características técnicas, principalmente a migração de contaminantes. Tentativas de melhoria das qualidades de solos supostamente inadequados também são importantes. Esta tese apresenta estudos sobre a migração dos íons \'CD POT.2+\', \'K POT.+\', \'CL POT.1-\' e \'F POT.-\' em latossolos residuais das formações Botucatu e Serra Geral e três diferentes misturas destes solos, com ênfase nos processos de sorção e difusão molecular. O potencial de retenção dos íons é avaliado através da construção de 33 isotermas de sorção resultantes de ensaios de equilíbrio em lote. Seus parâmetros são obtidos da adequação dos modelos linear, Freundlich e Langmuir as isotermas. O potencial de transporte dos íons é avaliado através de ensaios de difusão em colunas estanques, onde curvas teóricas produzidas no programa POLLUTE são ajustadas aos dados de concentração para a estimativa dos parâmetros de difusão. Os resultados dos estudos de retenção mostram que o \'CL POT.-\' experimenta sorção sob certas condições, o \'K POT.+\' e \'F POT.-\' possuem taxas semelhantes de retenção, e que a sorção do \'CD POT.2+\' se mostrou altamente dependente da composição da solução contaminante. Os ensaios de difusão resultaram em vários valores para o coeficiente de difusão efetiva (D*), mostrando que o fluxo difusivo dos íons diminui para solos mais argilosos. / There is a growing demand for materials that can be used in lining systems for waste disposal facilities. The use of tropical soils for this purpose is restricted due to the lack of technical knowledge about this type of material. Attempts to improve the quality of supposed unsuitable soils play also an important role. This thesis presents studies concerning the migration of the ions \'CD POT.2+\', \'K POT.+\', \'CL POT.-\' and \'F POT.-\' in latosoils from the Botucatu and Serra Geral formations and three different mixtures of these soils, with emphasis on sorption and molecular diffusion. Batch equilibrium tests were conduced to examine the retention capacity of the soils, and the sorption parameters are estimated by fitting the linear, Freundlich and Langmuir models to the experimental isotherm plots. The potential for these soils to transport ions is evaluated by diffusion tests, where theoretical curves produced in the POLLUTE code are used to estimate the effective diffusion coefficients (D*). The results show that the \'CL POT.-\' is sorbed under specific conditions and, therefore, it can not always be used as a conservative ion (i.e. nonreactive ion), \'K POT.+\' and \'F POT.-\' are sorbed in similar amounts, and that the \'CD POT.2+\' sorption is highly dependent on the contaminant solution composition. Several D* values are reported, showing that the diffusion rates are decreased for soils with more clay.

Les travaux présentés dans ce manuscrit sont consacrés à l'étude de la diffusion du dioxyde de carbone dissous et de l'éthanol dans une solution hydroalcoolique modèle représentant le champagne. La première partie de ce travail aborde les différents formalismes de la diffusion moléculaire, ainsi que les méthodes théoriques et expérimentales utilisées pour rendre compte de ce phénomène de transport. Une attention particulière est apportée à la dynamique moléculaire en champ de forces classiques qui est utilisé dans ce travail avec le logiciel GROMACS. Cette méthode théorique procure un point de vue novateur dans la recherche sur le champagne et plus particulièrement sur le rôle de chaque espèce majoritaire dans la diffusion du CO2. La spectroscopie RMN, ainsi qu'une méthode expérimentale basée sur l'étude du taux de grossissement des bulles, ont également été utilisées. Dans la deuxième partie, les résultats théoriques et expérimentaux sont présentés et comparés entre eux afin de valider le protocole des simulations de dynamique moléculaire. Les viscosités de la solution modèle et du champagne, ainsi que les rayons hydrodynamiques du CO2 et de l'éthanol sont également étudiés. La dernière partie du manuscrit concerne le partenariat avec l'entreprise Bull et l'étude des performances du logiciel GROMACS. L'expertise des équipes de Bull, ainsi que les outils développés par l'entreprise, permettent d'étudier le passage à l'échelle (ou "scalabilité") et le comportement parallèle de GROMACS pour la modélisation du champagne. / The work presented in this manuscript is devoted to the study of the diffusion of dissolved carbon dioxide and ethanol in a hydroalcoholic solution model representing Champagne wines. The first part of this work deals with the different formalisms of molecular diffusion, as well as theoretical and experimental methods used to account for this phenomenon of transport. Particular attention is paid to the classical force field molecular dynamics that is used in this work with the GROMACS software. This theoretical approach provides a new perspective in research on champagne and particularly on the role of each of the main species in CO2 diffusion. NMR spectroscopy, and an experimental method based on the study of the bubbles growth rate, were also used. In the second part, the theoretical and experimental results are presented and compared with each other to validate the protocol of molecular dynamics simulations. The viscosities of the model solution and of the champagne, as well as the hydrodynamic radii of CO2 and ethanol, are also investigated. The last part of the manuscript focuses on the partnership with the Bull company and the study of the GROMACS software performance. The expertise of and the tools developed by the Bull company are used to study the scalability and the parallel behavior of GROMACS for modeling champagne.

Extremely small pore size, low porosity, and ultra-low permeability are among the characteristics of shale rocks. In tight shale reservoirs, the nano-confinement effects that include large gas-oil capillary pressure and critical property shifts could alter the phase behaviors, thereby affecting the oil or gas production. In this research, two in-house simulation models, i.e., a compositionally extended black-oil model and a fully composition model are developed to examine the nano-pore confinement effects on convective and diffusive multicomponent multiphase fluid transport. Meanwhile, the effect of nano-confinement and rock intrinsic properties (porosity and tortuosity factor) on predicting effective diffusion coefficient are investigated. First, a previously developed compositionally extended black-oil simulation approach is modified, and extended, to include the effect of large gas-oil capillary pressure for modeling first contact miscible (FCM), and immiscible gas injection. The simulation methodology is applied to gas flooding in both high and very low permeability reservoirs. For a high permeability conventional reservoir, simulations use a five-spot pattern with different reservoir pressures to mimic both FCM and immiscible displacements. For a tight oil-rich reservoir, primary depletion and huff-n-puff gas injection are simulated including the effect of large gas-oil capillary pressure in flow and in flash calculation on recovery estimations. A dynamic gas-oil relative permeability correlation that accounts for the compositional changes owing to the produced gas injection is introduced and applied to correct for changes in interfacial tension (IFT), and its effect on oil recovery is examined. The results show that the simple modified black-oil approach can model well both immiscible and miscible floods, as long as the minimum miscibility pressure (MMP) is matched. It provides a fast and robust alternative for large-scale reservoir simulation with the purpose of flaring/venting reduction through reinjecting the produced gas into the reservoir for EOR. Molecular diffusion plays an important role in oil and gas migration in tight shale formations. However, there are insufficient reference data in the literature to specify the diffusion coefficients within porous media. Another objective of this research is to estimate the diffusion coefficients of shale gas, shale condensate, and shale oil at reservoir conditions with CO2 injection for EOR/EGR. The large nano-confinement effects including large gas-oil capillary pressure and critical property shifts could alter the phase behaviors. This study estimates the diffusivities of shale fluids in nanometer-scale shale rock from two perspectives: 1) examining the shift of diffusivity caused by nanopore confinement effects from phase change (phase composition and fluid property) perspective, and 2) calculating the effective diffusion coefficient in porous media by incorporating rock intrinsic properties (porosity and tortuosity factor). The tortuosity is obtained by using tortuosity-porosity relations as well as the measured tortuosity of shale from 3D imaging techniques. The results indicated that nano-confinement effects could affect the diffusion coefficient through altering the phase properties, such as phase compositions and densities. Compared to bulk phase diffusivity, the effective diffusion coefficient in porous shale rock is reduced by 102 to 104 times as porosity decreases from 0.1 to 0.03. Finally, a fully compositional model is developed, which enables us to process multi-component multi-phase fluid flow in shale nano-porous media. The validation results for primary depletion, water injection, and gas injection show a good match with the results of a commercial software (CMG, GEM). The nano-confinement effects (capillary pressure effect and critical property shifts) are incorporated in the flash calculation and flow equations, and their effects on Bakken oil production and Marcellus shale gas production are examined. The results show that including oil-gas capillary pressure effect could increase the oil production but decrease the gas production. Inclusion of critical property shift could increase the oil production but decrease the gas production very slightly. The effect of molecular diffusion on Bakken oil and Marcellus shale gas production are also examined. The effect of diffusion coefficient calculated by using Sigmund correlation is negligible on the production from both Bakken oil and Marcellus shale gas huff-n-puff. Noticeable increase in oil and gas production happens only after the diffusion coefficient is multiplied by 10 or 100 times. / Doctor of Philosophy / Shale reservoir is one type of unconventional reservoir and it has extremely small pore size, low porosity, and ultra-low permeability. In tight shale reservoirs, the pore size is in nanometer scale and the oil-gas capillary pressure reaches hundreds of psi. In addition, the critical properties (such as critical pressure and critical temperature) of hydrocarbon components will be altered in those nano-sized pores. In this research, two in-house reservoir simulation models, i.e., a compositionally extended black-oil model and a fully composition model are developed to examine the nano-pore confinement effects on convective and diffusive multicomponent multiphase fluid transport. The large nano-confinement effects (large gas-oil capillary pressure and critical property shifts) on oil or gas production behaviors will be investigated. Meanwhile, the nano-confinement effects and rock intrinsic properties (porosity and tortuosity factor) on predicting effective diffusion coefficient are also studied.

<div>Studies of turbulent combustion in the past mainly focus on problems with single-regime combustion. In practical combustion systems, however, combustion rarely occurs in a single regime, and different regimes of combustion can be observed in the same system. This creates a significant gap between our existing knowledge of combustion in single regime and the practical need in multi-regime combustion. In this work, we aim to extend the traditional single-regime combustion models to problems involving different regimes of combustion. Among the existing modeling methods, Transported Probability Density Function (PDF) method is attractive for its intrinsic closure of treating detailed chemical kinetics and has been demonstrated to be promising in predicting low-probability but practically important combustion events like local extinction and re-ignition. In this work, we focus on the model assessment and advancement of the Large Eddy Simulation (LES)/ PDF method in predicting turbulent multi-regime combustion.</div><div><br></div><div><div>Two combustion benchmark problems are considered for the model assessment. One is a recently designed turbulent piloted jet flame that features statistically transient processes, the Sydney turbulent pulsed piloted jet flame. A direct comparison of the predicted and measured time series of the axial velocity demonstrates a satisfactory prediction of the flow and turbulence fields of the pulsed jet flame by the employed LES/PDF modeling method. A comparison of the PLIF-OH images and the predicted OH mass fraction contours at a few selected times shows that the method captures the different combustion stages including healthy burning, significant extinction, and the re-establishment of healthy burning, in the statistically transient process. The temporal history of the conditional PDF of OH mass fraction/temperature at around stoichiometric conditions at different axial locations suggests that the method predicts the extinction and re-establishment timings accurately at upstream locations but less accurately at downstream locations with a delay of burning reestablishment. The other test case is a unified series of existing turbulent piloted flames. To facilitate model assessment across different combustion regimes, we develop a model validation framework by unifying several existing pilot stabilized turbulent jet flames in different combustion regimes. The characteristic similarity and difference of the employed piloted flames are examined, including the Sydney piloted flames L, B, and M, the Sandia piloted flames D, E, and F, a series of piloted premixed Bunsen flames, and the Sydney/Sandia inhomogeneous inlet piloted jet flames. Proper parameterization and a regime diagram are introduced to characterize the pilot stabilized flames covering non-premixed, partially premixed, and premixed flames. A preliminary model assessment is carried out to examine the simultaneous model performance of the LES/PDF method for the piloted jet flames across different combustion regimes.</div><div><br></div><div>With the assessment work in the above two test cases, it is found that the LES/PDF method can predict the statistically transient combustion and multi-regime combustion reasonably well but some modeling limitations are also identified. Thus, further model advancement is needed for the LES/PDF method. In this work, we focus on two model advancement studies related to the molecular diffusion and sub-filter scale mixing processes in turbulent combustion. The first study is to deal with differential molecular diffusion (DMD) among different species. The importance of theDMD effects on combustion has been found in many applications. However, in most previous combustion models equal molecular diffusivity is assumed. To incorporate the DMD effects accurately, we develop a model called Variance Consistent Mean Shift (VCMS) model. The second model advancement focuses on the sub-filter scale mixing in high-Karlovitz (Ka) number turbulent combustion. We analyze the DNS data of a Sandia high-Ka premixed jet flame to gain insights into the modeling of sub-filter scale mixing. A sub-filter scale mixing time scale is analyzed with respect to the filter size to examine the validity of a power-law scaling model for the mixing time scale.</div></div>

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Xylopia nitida and Xylopia sericea are commonly known as âembira-brancaâ and âpimenta do sertÃoâ, respectively, belonging to Annonaceae family. The chromatographic analysis of X. nitida roots allowed isolation of a trachlyobane diterpene, ent-trachlyoban-18,19-diol and its acetylated product, ent-18,19-diacetoxy-trachylobane, a kaurene diterpene, ent-kaur-16-en-18,19-diol, two aporphinic alkaloids, 5,6,6a,7-tetrahydro-1-methoxy-(6aS)-4H-benzo[de][1,3]benzodioxolo[5,6-g]quinoline e xylopine, and a glucoside, named 1-O-ethyl-&#946;-D-glucopiranose. Also using chromatographic analysis of X. sericea fruits were obtained a kaurane diterpene, kauran-16&#946;-ol and a diterpenes mixture, ent-kaur-16-en-19-oic acid and beyer-15-19-oic acid. The structures of these compounds were elucidated by spectroscopic studies (IR, MS and NMR). In the second part of this work, has been showed the diffusion-ordered spectroscopy (DOSY) as a powerful tool in natural product mixture analysis. The assignment of NMR signals to specific components in a mixture is a challenging task. DOSY has provided important progress in this area, allowing the signals originating from individual components of different molecular sizes to be distinguished. However, when the sizes of the compounds are similar and/or the spectra are overlapped, signal assignment can easily become intractable. The use of a co-solute in a matrix-assisted DOSY (MAD) experiment can be a useful solution, improving diffusional (and sometimes spectral) resolution by exploiting selective binding to the matrix. The challenge is to apply MAD to molecules with high structural similarity, for example in natural product mixtures. Various surfactants, including SDS, AOT and CTAB have previously been shown to be effective in MAD analysis. Here we present an important addition, the Brij family of nonionic surfactants. We demonstrate the use of Brij micelles and other systems in mixed solvents with a variety of mixtures relevant to natural products. / Xylopia nitida e X. sericea, conhecidas popularmente como embira-branca e pimenta do sertÃo, respectivamente, sÃo espÃcies pertencentes à famÃlia Annonaceae. A anÃlise cromatogrÃfica dos extratos hexÃnico e etanÃlico das raÃzes de X. nitida possibilitou o isolamento de um diterpeno de esqueleto traquilobano, ent-traquiloban-18,19-diol e seu derivado acetilado, ent-18,19-diacetÃxi-traquilobano, um diterpeno de esqueleto caureno, ent-caur-16-en-18,19-diol, dois alcalÃides aporfÃnicos, 5,6,6a,7-tetraidro-1-metoxi-(6aS)-4H-benzo[de][1,3]benzodioxolo[5,6-g]quinolina e xylopina e um glicosÃdeo, 1-O-etil-&#946;-D-glicopiranose, todos de carÃter inÃdito na literatura, exceto os dois Ãltimos. AtravÃs da anÃlise cromatogrÃfica do extrato hexÃnico dos frutos de X. sericea foi possÃvel obter um diterpeno de esqueleto caurano denominado cauran-16&#946;-ol e uma mistura de diterpenos, Ãcido ent-caur-16-en-19-Ãico e Ãcido beier-15-en-19-Ãico. O isolamento dos constituintes quÃmicos presentes nos extratos da raiz e frutos de X. nitida e X. sericea, respectivamente, foi realizada por mÃtodos cromatogrÃficos convencionais e a determinaÃÃo estrutural das substÃncias isoladas foi realizada a partir de mÃtodos espectromÃtricos como: IV, EM, RMN 1H, 13C e DEPT 135 incluindo tÃcnicas bidimensionais como, COSY, HSQC e HMBC. A primeira parte deste trabalho relata o estudo quÃmico das raÃzes de X. nitida e dos frutos de X. sericea. A espectroscopia ordenada por difusÃo ou DOSY (Diffusion Ordered Spectroscopy) provà um meio para uma âseparaÃÃo virtualâ de compostos, atravÃs de um mapa bidimensional onde em um eixo temos o deslocamento quÃmico e em outro observamos o coeficiente de difusÃo (D) das molÃculas na mistura. A separaÃÃo de sinais somente à possÃvel quando espÃcies difundem a diferentes velocidades. Na quÃmica de produtos naturais, frequentemente nos deparamos com misturas de compostos quimicamente semelhantes e de tamanhos muito similares, o que torna limitado o experimento DOSY tradicional. Entretanto, o coeficiente de difusÃo das substÃncias pode ser modificado pela adiÃÃo de co-solutos e/ou co-solventes, surgindo a partir daà a espectroscopia ordenada por difusÃo assistida por matriz (matrix-assisted DOSY ou MAD). VÃrios surfactantes, incluindo SDS, AOT e CTAB tÃm se mostrado efetivos em anÃlises por MAD. Neste trabalho, experimentos MAD foram realizados com algumas misturas de produtos naturais com similaridades estruturais utilizando o Ãcido perfluoro-octanÃico (PFOA), polivinilpirrolidona (PVP) e os surfactantes Brij 78 e 98, que por sua vez, ainda nÃo haviam sido utilizados para esse propÃsito. NÃs tambÃm demonstramos a formaÃÃo de micelas de Brij 78 e 98 em misturas dos solventes DMSO-d6 e D2O.