Dans cette thèse, nous étudions des écoulements caractérisés par un faible nombre de Mach. Dans une première partie, nous développons un schéma numérique permettant la résolution des équations de Navier-Stokes à faible nombre de Mach. L’équation de continuité est résolue par une méthode de volumes finis, tandis que l’équation de conservation de la quantité de mouvement et l’équation d’évolution de la température sont résolues par éléments finis. Le schéma ainsi développé assure la préservation des états constants. Dans une seconde partie, nous faisons l’analyse d’un modèle de type faible Mach spécifique, dans lequel la pression thermodynamique est considérée constante, et la viscosité est une fonction particulière de la température. Nous montrons l’existence, l’unicité et la régularité des solutions, ainsi qu’un résultat de principe du maximum pour la température. Enfin dans une troisième partie, nous développons un schéma numérique permettant de simuler les équations de ce modèle. L’accent est mis sur la discrétisation de l’équation de température, qui est de type volumes finis. Plusieurs schémas sont étudiés et comparés sur des critères de précision et de respect du principe du maximum. L’équation de conservation de la quantité de mouvement est discrétisée par éléments finis, définissant un nouveau schéma combiné. / In this thesis, we study some flows characterized by a low Mach number. In a first part, we develop a numerical scheme allowing the resolution of the Navier-Stokes equations in the low Mach number approximation. The continuityequation is solved by a finite volume method, while the momentum and temperature equations are solved by finite elements. The scheme ensures the preservation of constant states. In a second part, we analyze a specific low Mach type model, in which the thermodynamic pressure is considered constant, and the viscosity is a particular function of the temperature. We show the existence, the uniqueness and the regularity of the solutions, as well as a maximum principle result for the temperature. Finally, in a third part, we develop a numerical scheme to simulate the equations of this model. Emphasis is placed on the discretization of the temperature equation, which is of finite volume type. Several schemes are studied and compared on criteria of precision and respect of the maximum principle. The momentum equation is discretized by finite elements, defining a new combined scheme.

No description available.

No description available.

The Major Intrinsic Proteins are represented in all forms of life; plants, animals, bacteria and recently archaebacteria have all been shown to express at least one member of this superfamily of integral membrane proteins. We have overexpressed the E. coli aquaglyceroporin, glycerol facilitator (GlpF), to use as a model for studying membrane protein structure, folding and stability. Understanding membrane protein folding, stability, and dynamics is required for a molecular explanation of membrane protein function and for the development of interventions for the hundreds of membrane protein folding diseases. X-ray analysis of GlpF crystals shows that the protein exits as a tetramer in the crystallized state [1]. However, preparations of stable aqueous detergent solutions of GlpF in its native oligomeric state have been difficult to make; the protein readily unfolds and forms non-specific aggregates in many detergents. Here, I report the study of the structure and stability of the glycerol facilitator in several detergent solutions by blue native and sodium dodecyl sulphate polyacrylamide gel electrophoresis, circular dichroism, and fluorescence. For the first time, stable protein tetramers were prepared in two different detergent solutions (dodecyl maltoside (DDM) and lyso-myristoyl phosphatidylcholine (LMPC)) at neutral pH. Thermal unfolding experiments show that the protein is slightly more stable in LMPC than in DDM and that the thermal stability of the helical core at 95oC is slightly greater in the former detergent. In addition, tertiary structure unfolds before quaternary and secondary structures in LMPC whereas unfolding is more cooperative in DDM. The high stability of the protein is also evident from the unfolding half-life of 8 days in 8 M urea suggesting that hydrophobic interactions contribute to the stability. The GlpF tetramers are less resistant to acidic conditions; LMPC-solubilized GlpF shows loss of tertiary and quaternary structure by pH 6, while in DDM the tertiary structure is lost by pH 5, however the tetramer remains mostly intact at pH 4. The implications of thermal and chemical stress on the stability of the detergent-solubilized protein and its in vivo folding are discussed. / October 2008

In this study, we prepare the zinc oxide nanotip with aqueous solution deposited on ZnO nucleation layer. The directions of nanotip are formed with different ZnO nucleation layer time. The thermal annealing with N2 ambiance at 300 ¢J for 1 hr increase the UV emission and decrease the defects. We use ZnO nanotip as an anti-reflection layer because of surface roughness and optical interference. ZnO nanotip with rough surface decreases reflection and enhance the transmission, so we use ZnO nanotip as an anti-reflection layer, after growin ZnO nanotip on solar cell the efficiency of solar cell was enhancement.

We determine the conditions under which half-maximal matter coupled gauged supergravity in seven dimensions admits a chiral circle reduction to yield a matter coupled gauged supergravity in six dimensions with 8 real supersymmetry. Solving these conditions we nd that the SO(2; 2) and SO(3; 1) gauged 7D supergravities give a U(1)R, and the SO(2; 1) gauged 7D supergravity gives an Sp(1)R gauged chiral 6D supergravity coupled to certain matter multiplets. In the 6D models obtained, with or without gauging, we show that the scalar fields of the matter sector parametrize the coset SO(p + 1; 4)=SO(p + 1) SO(4), with the (p + 3) axions corresponding to its abelian isometries. We then derive the necessary and sufficient conditions for the existence of a Killing spinor in N = (1; 0) gauge 6D supergravity coupled to a single tensor multiplet, vector multiplets and hypermultiplets. We show that these conditions imply most of the eld equations. We also determine the remaining equations that need to be satised by an exact solution. In this framework, we nd a novel 1=8 supersymmetric dyonic string solution with nonvanishing hypermultiplet scalars. The activated scalars parametrize a 4 dimensional submanifold of a quaternionic hyperbolic ball. The key point is that we employ an identity map between this submanifold and the internal space transverse to the string worldsheet, thereby nding a higher dimensional generalization of Gell- Mann-Zweibach tear-drop solution.

We determine the conditions under which half-maximal matter coupled gauged supergravity in seven dimensions admits a chiral circle reduction to yield a matter coupled gauged supergravity in six dimensions with 8 real supersymmetry. Solving these conditions we nd that the SO(2; 2) and SO(3; 1) gauged 7D supergravities give a U(1)R, and the SO(2; 1) gauged 7D supergravity gives an Sp(1)R gauged chiral 6D supergravity coupled to certain matter multiplets. In the 6D models obtained, with or without gauging, we show that the scalar fields of the matter sector parametrize the coset SO(p + 1; 4) / SO(p + 1) X SO(4), with the (p + 3) axions corresponding to its abelian isometries. We then derive the necessary and sufficient conditions for the existence of a Killing spinor in N = (1; 0) gauge 6D supergravity coupled to a single tensor multiplet, vector multiplets and hypermultiplets. We show that these conditions imply most of the eld equations. We also determine the remaining equations that need to be satised by an exact solution. In this framework, we nd a novel 1=8 supersymmetric dyonic string solution with nonvanishing hypermultiplet scalars. The activated scalars parametrize a 4 dimensional submanifold of a quaternionic hyperbolic ball. The key point is that we employ an identity map between this submanifold and the internal space transverse to the string worldsheet, thereby nding a higher dimensional generalization of Gell- Mann-Zweibach tear-drop solution.

In this study, we prepare the zinc oxide one-dimensional nanostructures with aqueous solution on GaN substrate. The morphologies of nanotip, nanorod and nanotube are formed with different modulation and chemical solutions. The thermal annealing with N2O ambiance at 300 ¢XC for 1 hr increase the UV emission and decrease the defects. The limit of choosing the substrate to grow ZnO nanostructures is lattice mismatch between ZnO and substrate. The buffer layer is sputtered on substrate to remove the limit. The pattern of buffer layer also can be used for selective area growth. Nanotip structure with rough surface shows the obvious lotus effect and nanotube structure with more active site and more surface area shows the better photocatalysis efficiency than nanotip structure.

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