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Kirsch, Paul Daniel. "Surface and interfacial chemistry of high-k dielectric and interconnect materials on silicon." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3034557.
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Tong, Jinhong. "Study of Interactions Between Diffusion Barrier Layers and Low-k Dielectric Materials for Copper/Low-k Integration." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc4384/.
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The shift to the Cu/low-k interconnect scheme requires the development of diffusion barrier/adhesion promoter materials that provide excellent performance in preventing the diffusion and intermixing of Cu into the adjacent dielectrics. The integration of Cu with low-k materials may decrease RC delays in signal propagation but pose additional problems because such materials are often porous and contain significant amounts of carbon. Therefore barrier metal diffusion into the dielectric and the formation of interfacial carbides and oxides are of significant concern. The objective of the present research is to investigate the fundamental surface interactions between diffusion barriers and various low-k dielectric materials. Two major diffusion barriers¾ tatalum (Ta) and titanium nitride (TiN) are prepared by DC magnetron sputtering and metal-organic chemical vapor deposition (MOCVD), respectively. Surface analytical techniques, such as X-ray photoelectronic spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) are employed.
Ta sputter-deposited onto a Si-O-C low dielectric constant substrate forms a reaction layer composed of Ta oxide and TaC. The composition of the reaction layer varies with deposition rate (1 Å-min-1 vs. 2 Å-sec-1), but in both cases, the thickness of the TaC layer is found to be at least 30 Å on the basis of XPS spectra, which is corroborated with cross-sectional TEM data. Sputter-deposited Cu will not wet the TaC layer and displays facile agglomeration, even at 400 K. Deposition for longer time at 2 Å-sec-1 results in formation of a metallic Ta layer. Sputter deposited Cu wets (grows conformally) on the metallic Ta surface at 300 K, and resists significant agglomeration at up to ~ 600 K. Cu diffusion into the substrate is not observed up to 800 K in the UHV environment.
Tetrakis(diethylamido) titanium (TDEAT) interactions with SiO2, Cu and a variety of low-k samples in the presence (~ 10-7 Torr or co-adsorbed) and absence of NH3 result in different products. TDEAT interactions with SiO2 are dominated by Ti interactions with substrate oxygen sites, and that Ti oxide/sub-oxide bond formation can proceed with relatively low activation energy. No Ti carbide or Si carbide formation is observed. Co-adsorption of TDEAT and NH3 on SiO2 at 120K followed by annealing to higher temperature results in enhanced Ti-N bond formation, which is stable against oxidation up to 900K in UHV. Similarly, continuous exposures of TDEAT on SiO2 at 500K in the presence of NH3 exhibit a relatively enhanced Ti-N spectral component. Co-adsorption of NH3 and TDEAT on Cu (poly) surface at 120K, followed by annealing to 500K, results in complete desorption of Ti, N or C-containing species from the Cu substrate. Reaction of TDEAT with a Cu surface at 500K yields a Ti-alkyl species via a b-hydride elimination pathway. TDEAT/Cu interactions are not observably affected by overpressures of NH3 of 10-7 Torr. TDEAT interaction with a porous carbon doped oxide low-k substrate at 700K demonstrates undissociated or partly dissociated Ti-NR species trapped in the dielectrics matrix due to its high porosity. In addition, carbide formation is observed from C(1s) XPS spectra. For a hydrocarbon low-k film, the majority sites (carbon) are highly unreactive towards TDEAT even at higher temperature due to a lack of functional groups to initiate the TDEAT/low-k surface chemistry.
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Genevaux, Pierre. "Genetic and phenotypic analysis of Escherichia coli k-12 adhesion to inanimate surface." Metz, 1998. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1998/Genevaux.Pierre.SMZ9860.pdf.
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The inherent tendency of bacteria to adhere and colonize natural and artificial surfaces is regarded as a fundamental aspect of bacterial pathogenesis and ecology. The interest in understanding cell surface components that mediate attachment to inanimate surface led us to focus on the identification of genes associated with this phenomenon. To this purpose, the well-characterized bacterium Escherichia coli K-12 and a polystyrene surface were used as model. An adhesion assay was first developed and used to screen 7000 mini-Tn10 insertion mutants of the strain E. Coli K- 12 W3110. One percent of these mutants was found to exhibit a reduced adhesion. The precise location of the mini- Tn10 insertion within the affected gene in the adhesion mutants was determined. Twenty-five adhesion mutants harbored the insertions in the fim operon, responsible for type 1 fimbriation. The data obtained indicated a major role of type 1 fimbriae and a direct involvement of the type 1 fimbriae specific adhesion FimH in adhesion to polystyrene. Twelve insertions were located in genes involved in flagella biosynthesis. The loss of adhesion observed appeared to be mainly due to the attenuated fimbriation caused by the flagella mutations and to the dysfunctional motility. Seven mutants harbored insertions in genes involved in lipopolysaccharide core biosynthesis. The loss of adhesion exhibited by these deep rough mutants was mainly associated with altered type 1 fimbriae production and, to a lesser extent, with defective motility. Three adhesion mutants had insertions in the dsbA gene. In spite of the pleiotropic character of the dsbA mutations, the observed loss of adhesion to polystyrene appeared to be most correlated with the considerably reduced amount of fimbriae. Chapter VI describes a group of five adhesion mutants that harbored insertions the phnI, yhhT, hisT and abc genes and in one of the three IS186 elements of the E. Coli chromosomeL'adhésion bactérienne sur des surfaces artificielles est un aspect fondamental de l’écologie et de la pathologie microbienne. Dans cette étude, la recherche de gènes et de structures cellulaires contrôlants les interactions entre une population bactérienne et une surface inerte a été entrepris. Un modèle d’étude, composé de la souche bactérienne Escherichia coli et d'une surface de polystyrène, a été choisi. Un essai mesurant les capacités adhésive d'une bactérie a été développé afin de cribler 7000 mutants de la souche E. Coli K-12 W3110. Un pour-cent des mutants cribles adhéraient moins que la souche parentale. La position précise de la mutation au sein des gènes affectes a été déterminée pour chacun des mutants de l’adhésion. Vingt cinq mutations étaient positionnées dans l'operon fim, impliqué dans la synthèse de fimbriae de type 1. Les résultats obtenus indiquaient un rôle majeur des fimbriae de type 1, et plus particulièrement de l’adhésion spécifique, fimh, dans l’adhésion sur polystyrène. Douze insertions ont été localisées dans des gènes impliqués dans la synthèse du flagellum. La perte d’adhésion observée chez ces mutants était associée à la perte de motilité et a un effet indirect des ces mutations sur la production de fimbriae. Sept mutations ont été localisées dans des gènes impliqués dans la synthèse du noyau lipopolysaccharidique. Dans ce cas, pas d’évidences pour un rôle direct du noyau lipopolysaccharidique dans l’adhésion sur polystyrène ont pu être observées. La perte d’adhésion était associée à la production réduite de fimbriae et aux changements de motilité observés chez ces mutants. Trois mutations ont été localisées dans le gène dsbA. L'effet de ces mutations sur la production de fimbriae était le principal facteur affectant les propriétés adhésives. Le chapitre VI décrit un groupe de cinq mutants de l’adhésion dans lesquels les mutations ont été localisées dans les gènes phnI, yhhT, hisT et abc ainsi que dans une des IS186 d'E. Coli
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Joseph, Genora M. D. "Improved dust dispersion modelling for surface quarries : an optimized RANS k − ε approach." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33767/.
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Conventional dust dispersion models which employ Gaussian concentration distributions are routinely applied to predict the dispersion and deposition of fugitive dust arising from quarrying activity. However, these models are known to over-predict the long range transport of particulates beyond the confines of the quarry pit, because their complex terrain algorithms are unable to accommodate the steep gradients which are typically encountered in quarry excavations. They therefore cannot account for the internal flow regimes which contribute to the removal of suspended particulates from the air stream. Consequently, a need arises within the extractive industries, for improved dust dispersion models that are not constrained by quarry topography. This research project attempts to address this deficiency in the modelling of dust emissions from quarry blast events, by presenting an optimized RANS k−ε approach which can adequately simulate the flow-field in which particulates are entrained under a range of meteorological conditions. The stages involved in the incremental development of the numerical model are documented in the thesis, and commence with characterization of the atmospheric boundary layer. In particular, the Monin-Obukhuv Similarity Theory is applied to parametrize the atmospheric surface layer, which exerts the most influence on the dispersion and deposition of near-ground particulate emissions. Modifications to the standard k − ε model coefficients and the inclusion of buoyancy source terms have been adopted in this work, in accordance with previous studies by Alinot and Masson (2005). These modifications ensure that the turbulence closure equations are compatible with Monin-Obukhuv Similarity scaling of the atmospheric surface layer. The Businger-Dyer flux profile functions have been employed to introduce stability modifications to the logarithmic velocity, temperature and turbulence profiles which have been defined at the inlet boundaries of the computational domain to enable numerical representation of both adiabatic and diabatic atmospheric conditions. Furthermore, the Lagrangian Discrete Phase Model has been coupled with Eulerian solution of the flow field to provide a robust means of replicating fugitive dust dispersion through the stochastic tracking of injected particulates. The project also presents a consolidated post-processing methodology to incorporate wind direction variability due to mesoscale atmospheric effects into the CFD model. This methodology use the Moore (1976) equation to parametrize the standard deviation of wind direction variability and proposes a novel, Gaussian probability weighted averaging procedure to arrive at a resultant plume which accounts for the influence of mesoscale wind variability on particulate trajectory and improves the k −ε predictions of lateral spreading of the dust plume. Simulations of flow and dispersion over a series of idealized cosine depressions of varying aspect ratio have been used to assess model predictions of the flow regime and the corresponding plume attenuation within artificial valleys. To allow the model to accommodate negative terrain elevations and to produce profiles of the flow variables which conform to wall topography, a wall-distance scalar has been introduced to ensure consistency of the inlet profile with the flow solution within the domain. These simulations have demonstrated that the proposed model surpasses UK-ADMS in terms of its ability to resolve strong recirculation regimes in deep depressions. The project culminates in a case study of the Old Moor Quarry in Buxton, Derbyshire. This case study tests the viability of the proposed k−ε model and validates the model predictions of dust dispersion with field measurements obtained over the course of a monitoring campaign of approximately one month duration. Meteorological pre-processing steps in accordance with the findings of Holtslag and Van Ulden (1983) have been employed to derive atmospheric surface layer input parameters from routine meteorological data measured at the quarry site, eliminating the need for sophisticated meteorological measurements. Dust dispersion predictions obtained using the conventional dust dispersion model UK-ADMS, have been compared to the CFD model results to demonstrate the improved prediction accuracy of the proposed k −ε approach. Notably, the CFD model is shown to account for the various flow regimes which arise due to the combined effects of the site meteorology and the complex terrain of the quarry excavation. Importantly, the statistical Performance metrics, FAC2, MG, FB and NMSE recommended by Hanna et al. (2004) for the evaluation of dispersion model performance, have been used to assess the accuracy of fugitive dust deposition predictions obtained from the proposed model. The performance evaluation exercise indicates that the buoyancy modified k − ε model outperforms UK-ADMS for all of the metric tests. The incorporation of the wind variability weighted averaging procedure in the case study simulations is seen to reduce uncertainty due to random error, quantified by NMSE. This due to the fact that the wind variability averaging procedure evens out outlying predictions which may be due to the inherent stochasticity of the DPM model.
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Milton, Brian E. "Lateral surface superlattices in strained InGaAs layers." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340295.
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Génevaux, Pierre Bauda Pascale. "ETUDE GENETIQUE ET PHENOTYPIQUE DE L'ADHESION D'ESCHERICHIA COLI K-12 SUR UNE SURFACE INERTE /." [S.l.] : [s.n.], 1998. ftp://ftp.scd.univ-metz.fr/pub/Theses/1998/Genevaux.Pierre.SMZ9860.pdf.
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Tanner, Robert E. "The structure of the rutile TiOâ‚‚(110) surface and Ni/TiOâ‚‚ nanoislands." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325929.
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HASNAOUI, MOULAY LAHEEN. "Etude par exafs de surface de l'interface si/gaas(110) au seuil k de silicium." Paris 11, 1994. http://www.theses.fr/1994PA112435.
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Ce travail, motive initialement par les problemes lies a la fabrication d'heterojonctions si-gaas, a eu pour but une definition precise du site d'adsorption du silicium sur la face (110) d'un substrat d'arseniure de gallium, puis une caracterisation du mode de croissance. Les experiences d'exafs au seuil k du silicium ont ete effectuees sur la ligne focalisee sa32, en utilisant la polarisation du rayonnement synchroton. Des epaisseurs croissantes ont ete deposees, a partir d'une demi-monocouche, et les resultats principaux sont les suivants. Le site d'adsorption initial est situe entre deux atomes de gallium le long de l'axe 001 et a egale distance des trois atomes du substrat les plus proches. Les atomes de silicium sont a environ 1 a au-dessus de la surface de gaas. L'augmentation du depot (vers 0. 8 mc) va entrainer un deplacement du si vers le centre des intervalles entre deux atomes du substrat, on obtient alors une structure en zig-zag ou seules sont visibles les liaisons adsorbat-substrat, ce dernier imposant donc sa structure. Au-dela de une monocouche l'interaction entre atomes de silicium est suffisamment forte pour faire apparaitre des liaisons entre ces atomes et donc des distances si-si a 2. 35 a carac teristiques du silicium pur. Une monocouche est complete et les atomes supplementaires forment avec ceux du premier plan, pour des epaisseurs de l'ordre de 1. 5 mc, des petits agregats d'environ six atomes qui coexistent avec des chaines courtes en zig-zag. Lorsqu'on augmente le depot, la croissance ne s'effectue pas couche par couche mais plutot selon le mode stranski-krastanov avec formation d'ilots tridimensionnels au-dessus de la premiere couche. Finalement, a partir de trois a quatre monocouches, on obtient du silicium amorphe dont le degre de cristallinite va dependre de la temperature de depot
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Martini, David M. "Metallization and Modification of Low-k Dielectric Materials." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9754/.
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Aluminum was deposited onto both Teflon AF and Parylene AF surfaces by chemical vapor deposition of trimethylaluminum. This work shows that similar thin film (100 Angstroms) aluminum oxide adlayers form on both polymers at the low temperature dosing conditions used in the studies. Upon anneal to room temperature and above, defluorination of the polymer surfaces increased and resulted in fluorinated aluminum oxide adlayers; the adlayers were thermally stable to the highest temperatures tested (600 K). Angle-resolved spectra showed higher levels of fluorination toward the polymer/adlayer interface region. Copper films were also deposited at low temperature onto Teflon AF using a copper hexafluoroacetylacetonate-cyclooctadiene precursor. Annealing up to 600 K resulted in the loss of precursor ligands and a shift to metallic copper. As with aluminum adlayers, some polymer defluorination and resulting metal (copper) fluoride was detected. Parylene AF and polystyrene films surfaces were modified by directly dosing with water vapor passed across a hot tungsten filament. Oxygen incorporation into polystyrene occurred exclusively at aromatic carbon sites, whereas oxygen incorporation into parylene occurred in both aromatic and aliphatic sites. Oxygen x-ray photoelectron spectra of the modified polymers were comparable, indicating that similar reactions occurred. The surface oxygenation of parylene allowed enhanced reactivity toward aluminum chemical vapor deposition. Silicon-carbon (Si-Cx) films were formed by electron beam bombardment of trimethylvinylsilane films which were adsorbed onto metal substrates at low temperatures in ultra-high vacuum. Oxygen was also added to the films by coadsorbing water before electron beam bombardment; the films were stable to more than 700 K, with increasing silicon-oxygen bond formation at elevated temperatures. Copper metal was sputter deposited in small increments onto non-oxygenated films. X-ray photoelectric spectra show three-dimensional copper growth (rather than layer-by-layer growth), indicating only weak interaction between the copper and underlying films. Annealing at elevated temperatures caused coalescence or growth of the copper islands, with spectra indicating metallic copper rather than copper oxide.
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Cahill, Sarah M. "Variation of surface polysaccharides in the ST25 clonal lineage of Acinetobacter baumannii." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/207776/1/Sarah_Cahill_Thesis.pdf.
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This project provides a novel insight into the genetics of complex surface structures present in the ST25 lineage of the multi-drug resistant bacteria, Acinetobacter baumannii. The thesis employs a newly developed tool, Kaptive, to aid global tracking efforts of this pathogen and uncovers new structure variants which inform future therapeutic options.
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Campbell, Gordon R. O. (Gordon Ross Orion) 1969. "Lipopolysaccharide, K antigen, and other components of the bacterial cell surface important for S. meliloti-alfalfa symbiosis." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8581.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Biology, 2001.Includes bibliographical references (leaves 139-156).
Sinorhizobium meliloti can form a symbiotic relationship with alfalfa plants in which the bacteria fix atmospheric nitrogen into ammonia for the plant in exchange for nutrients. During this symbiosis, the bacteria live in organs called nodules that develop in the roots of the plant. This thesis explores a range of bacterial components necessary for an effective symbiosis. One overarching theme to these components is that most of them are involved with the bacterial cell surface. Chapter 2 is a study of the lpsB389 mutant, which codes for a predicted glycosyl transferase involved with LPS core synthesis. Bacteria carrying the lpsB389 mutation are capable of carrying out the first steps of nodule invasion on alfalfa plants. However, they display dramatic abnormalities upon entry into plant cells. In Chapter 3, I identified four new classes of mutants involved in K antigen synthesis. Finally, in Chapters 4 and 5, I made use of the newly sequenced S. meliloti genome to determine the locations of the insertions in 43 mutants identified by having an effect on the cell surf ace. Most of these mutants also have symbiotic defects. Chapter 4 examines a series of mutations that affect either LPS or other factors involved in membrane integrity. In contrast to a previous report, I found·that most of these mutants have symbiotic defects. In addition, this study has identified genes coding for proteins not previously recognized as being involved with the integrity of the cell surface or as being required for symbiosis including: GreA, and a protein with a Sua5/Yci0/YrdC family signature domain. Chapter 5 implicates many new genes and processes in symbiosis including: the vitamin B12 , or cobalamin; QxtA, a predicted terminal oxidase of respiration; a predicted magnesium and cobalt transporter; and the process of carbon fixation. Undoubtedly the genes, factors, and metabolic processes identified in these studies will lead to a greater understanding of the complex interaction between S. meliloti and alfalfa during symbiosis. Furthermore, since S. meliloti is closely related to a number of mammaljan and plant pathogens, these discoveries may also contribute to our understanding of how pathogens infect their hosts.
by Gordon R.O. Campbell.
Ph.D.
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Shaheed, Rawaa. "3D Numerical Modelling of Secondary Current in Shallow River Bends and Confluences." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34922.
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Secondary currents are one of the important features that characterize flow in river bends and confluences. Fluid particles follow a helical path instead of moving nearly parallel to the axis of the channel. The local imbalance between the vertically varying centrifugal force and the cross-stream pressure gradient results in generating the secondary flow and raising a typical motion of the helical flow. A number of studies, including experimental or mathematical, have been conducted to examine flow characteristics in curved open channels, river meanders, or confluences. In this research, the influence of secondary currents is studied on the elevation of water surface and the hydraulic structures in channel bends and confluences by employing a 3D OpenFOAM numerical model.
The research implements the 3D OpenFOAM numerical model to simulate the horizontal distribution of the flow in curved rivers. In addition, the progress in unraveling and understanding the bend dynamics is considered. The finite volume method in (OpenFOAM) software is used to simulate and examine the behavior of secondary current in channel bends and confluences. Thereafter, a comparison between the experimental data and a numerical model is conducted. Two sets of experimental data are used; the data provided by Rozovskii (1961) for sharply curved channel, and the dataset provided by Shumate (1998) for confluent channel.
Two solvers in (OpenFOAM) software were selected to solve the problem regarding the experiment; InterFoam and PisoFoam. The InterFoam is a transient solver for incompressible flow that is used with open channel flow and Free Surface Model. The PisoFoam is a transient solver for incompressible flow that is used with closed channel flow and Rigid-Lid Model. Various turbulence models (i.e. Standard k-ε, Realizable k-ε, LRR, and LES) are applied in the numerical model to assess the accuracy of turbulence models in predicting the behaviour of the flow in channel bends and confluences. The accuracies of various turbulence models are examined and discussed.
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Schlageter, Martin [Verfasser], and Powell A. [Akademischer Betreuer] K. "Click chemistry modification of surface-bound peptides towards applications in printable electronics / Martin Schlageter. Betreuer: A. K. Powell." Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1082294527/34.
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Kollmannsberger, Sebastian Ludwig [Verfasser], Ulrich K. [Akademischer Betreuer] Heiz, Ulrich K. [Gutachter] Heiz, and Richard W. [Gutachter] Fischer. "Thermal and Photo-Activated Molecular Mechanisms of Surface Processes on TiO2(110) and GaN(0001) / Sebastian Ludwig Kollmannsberger ; Gutachter: Ulrich K. Heiz, Richard W. Fischer ; Betreuer: Ulrich K. Heiz." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/116152889X/34.
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Suggs, Allison Elizabeth. "Kr-F laser surface treatment of poly(methyl methacrylate), glycol-modified poly(ethylene terephthalate), and polytetrafluoroethylene for enhanced adhesion of Escherichia Coli K-12." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35182.
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Environmental response as determined by the cell-polymer interaction stands as the greatest restriction to the implementation of new polymeric materials. Cell-polymer interactions are most influenced by substrate surface free energy, surface chemistry, topography, and rigidity[1]. Alteration of these properties through surface treatment has become a common approach to attain the desired cellular interaction.
This study investigates Kr-F excimer laser(248 nm) surface modification of poly(methyl methacrylate), glycol-modified poly(ethylene terephthalate), and polytetrafluoroethylene and its effect on the adhesion of Escherichia Coli K-12 bacteria. These three polymers were chosen for their very different mechanisms of ablation as well as their range of surface free energies and bacterial responses[2-4].
Polymers were ablated using a pulsed Kr-F excimer laser with a dose of 3.3x 10-9 W/cm2 per pulse. This high level of UV radiation was sufficient to cause significant surface damage on both PMMA and PTFE. PETG showed some signs of wavering in the surface and material removal was confirmed through optical microscopy. Due to the extensive damage associated with ablation, a much lower-powered, continuous beam Kr-F laser was used for contact angle samples. It delivered a dose of 1.27 W/cm2. Contact angle measurements were then taken which showed dose-dependent surface free energy in all three polymers.
Following ablation, bacterial adhesion to PETG was improved two-fold, while it decreased in both PTFE and PMMA. Surface chemistry analysis supported the idea that the ablation occurred through chain scission, since there were no new surface groups created.
There were significan texture modifications observed in PTFE and PMMA whicle PETG demonstrated the rolling structure characteristic of polyesters following laser ablation described in Wefers et al [4] and Hopp et al [5]. Contact angle measurements showed a correlation between radiation dose and surface free energy of all three polymers.Master of Science
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Vanthanouvong, Viengphet. "Studies of the Elemental Composition of Airway Surface Liquid with Relevance to Cystic Fibrosis." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7245.
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Rötzer, Marian [Verfasser], Ulrich K. [Akademischer Betreuer] Heiz, Ulrich K. [Gutachter] Heiz, Richard W. [Gutachter] Fischer, and Günther [Gutachter] Rupprechter. "Surface chemistry of unsaturated hydrocarbons on metal based nanoparticles and size-selected clusters under UHV conditions / Marian Rötzer ; Gutachter: Ulrich K. Heiz, Richard W. Fischer, Günther Rupprechter ; Betreuer: Ulrich K. Heiz." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/119081868X/34.
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Karlsson, Patrik. "Surface Science Studies of Metal Oxides Formed by Chemical Vapour Deposition on Silicon." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7088.
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Lahr, David Louis. "Molecular oxygen adsorbates at a Au/Ni(111) surface alloy and their role in catalytic CO oxidation at 70 - 250 K." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36250.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2006.Includes bibliographical references.
Oxygen is observed to adsorb molecularly on 0.13 - 0.27 ML Au/Ni(1 111) surface alloys at 77 K, in stark contrast to dissociative adsorption on Ni and no adsorption on Au surfaces. Molecular 02 adsorbates on the Au/Ni(111) surface alloy are identified by their 0=0 vibrational modes at 790, 850 and 950 cm-', measured by electron energy loss spectroscopy. Possible Ni adsorption sites for the three types of molecularly adsorbed 02 are proposed. The dramatic change in Ni reactivity occurs within a narrow Au coverage range around 0.13 ML Au and arises from poorer overlap between the Ni d-band and the 02 LUMO as the Ni d-band shifts to lower energy with increasing Au content of the Au/Ni surface alloy. The amount of molecular adsorption as a function of Au coverage cannot be described by an analytical or simulated model based on Au atom proximity to Ni sites, suggesting the role of cooperative effects in 02 stabilization. Adsorbed molecular 02 dissociates between 110 to 150 K. No oxygen desorbs. At Au coverages greater than 0.27 ML, the energy of the Ni d-band is shifted sufficiently low to destabilize oxygen adsorption.
(cont.) Carbon monoxide is catalytically oxidized on the Au/Ni(111) surface alloy at 70 and 77 K via a Langmuir-Hinshelwood mechanism. Molecularly adsorbed 02 is identified as the reactant with adsorbed CO. The reaction probability at 77 K is 0.4. Atomically adsorbed O and CO do not react at 77 or 300 K. Between 108 and 125 K, CO reacts with either atomic O adsorbed on Au atoms or with molecularly adsorbed 02. Between 125-150 K, CO2 production coincides with 02 dissociation, suggesting a "hot atom" mechanism. The reactive potential energy surfaces likely have a late transition state. This work demonstrates that the nanoscale size of Au clusters and its associated quantum size effect are not the necessary feature that enables Au-catalyzed low temperature CO oxidation. Rather, this work strongly suggests that an adsorbed 02 species similarly stabilized at the perimeter of Au nanoparticles is the critical reactant in supported oxide systems.
by David Louis Lahr.
Ph.D.
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Čech, Josef. "Příspěvek k realizaci nákladově a energeticky úsporných rodinných domů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-233805.
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Dissertation focuses on the verification of construction family houses made of concrete shell block with internal thermal insulation system. The construction technology is transferred to the Czech Republic from France. The work focuses on building envelope. The suitability of implementation is assessed on the basis of verification selected thermal technical requirements placed on building envelope. Requirements are specified by legislation in force in the ČR. The verification was performed by using software simulations and measurements on realized buildings. Critical areas of construction technology were identified on the basis software simulations and measurements on site. It was suggested solution, in which critical areas comply the thermal technical requirements. The building envelope was checked also using the thermography imaging on site. Continuous measurement of interior temperature was used to evaluate thermal comfort in the room. In the completed buildings was tested airtightness of the building envelope, which revealed other critical areas of the building envelope. Critical areas are necessary to solve with sufficient care. The economic cost of implementing each variants of exterior walls made of concrete shell block with internal thermal insulation were compared with the economic costs of implementing external walls made of burnt clay hollow blocks and made of burnt clay hollow blocks with external thermal insulation system ETICS. Subsequently, the economic return was calculated for individual variants of external walls made of concrete shell blocks with internal thermal insulation. From the environmental viewpoint was made comparison of production greenhouse gas CO2 and SO2 (cause acid rains) during the life cycle of the individual variations of exterior walls made of concrete shell blocks with system of internal thermal insulation, exterior walls made of burnt clay hollow blocks and burnt clay hollow blocks with external thermal insulation syst
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Hoffmann, Max Jakob [Verfasser], Karsten [Akademischer Betreuer] Reuter, and Ulrich K. [Akademischer Betreuer] Heiz. "First-principles Multi-scale Simulations of Dynamic Catalyst Surfaces : CO Oxidation from Palladium Surface Oxide to Palladium Metal / Max Jakob Hoffmann. Gutachter: Karsten Reuter ; Ulrich K. Heiz. Betreuer: Karsten Reuter." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1054753016/34.
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Van, Heerden Karien. "Geological and anthropogenic impacts on inorganic water quality at rural clinics in the Limpopo Province, South Africa / van Heerden, K." Thesis, North-West University, 2011. http://hdl.handle.net/10394/6978.
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This study gives insight to the origin of pollution in the water resources of the Limpopo province of South Africa. The Limpopo province is the largest rural province in South Africa. Up to 40% of the total population does not have access to sufficient water supply, resulting in adverse health effects. The purpose of this study is to determine (1) the degree of inorganic pollution of borehole water; (2) to identify the pollution sources, and (3) to determine whether the pollution is inherited from the surface water that recharges the groundwater or is caused on site near the bore holes. In order to achieve these objectives, surface water quality data (14 675 samples) and borehole water data (340 samples) at health facilities were analysed. A pollution index, defined by the following ratio:
Pollution index (%) = 100 x ([Cl–] + 2[SO4^-2] + [NO3-] + 3[PO4^-3]) ÷ ([Cl-] + 2SO4^-2 + [NO3-] + [PO4^-3] + [HCO3-])
was used to determine the percentage of contribution of each chemical species towards pollution. This ratio is based on the fact that bicarbonate is released during chemical weathering of rocks whereas sulphate, nitrate, chloride, and phosphate are anthropogenic in origin. The pollution index shows that 6% of the surface waters and 21% of the borehole water is severely polluted. The pollution of the surface water is characterized by high concentrations of sulphate whereas the pollution of the borehole water is characterized by high concentrations of chloride. This indicates that the pollution of the borehole water is not so much the result of the infiltration of polluted surface water, but rather the result of on–site pollution on the surface near the bore holes.Thesis (M.Sc. (Geography and Environmental Studies))--North-West University, Potchefstroom Campus, 2011.
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Almutairi, Alanoud. "Electronic band structure equations and Fermi surface evolution from 2D materials to 3D layered superconducting compounds." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/134414/1/Alanoud%20Mulfi%20Z_Almutairi_Thesis.pdf.
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A simple approach for extracting the superconducting gap of materials from trendline fittings of key sections of their Electronic Band Structures (EBS), calculated using Density Functional Theory (DFT), is presented. The proposed approach works well for very different compositions, structure types and superconducting transition temperatures, indicating that it is robust, reliable and versatile. This approach provides many advantages in terms of required computational time and power, compared with similar information extracted from phonon dispersion calculations, making it accessible to wider DFT-computational chemistry and physics communities. The approach also identifies requirements for superconductivity and indirectly contributes towards understanding of superconductivity mechanisms.
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Lie, Fee Li. "Interface Formation Between High Dielectric Permittivity Films and III-V Compound Semiconductors using HF Chemistries and Atomic Layer Deposition." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/204301.
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In-based III-V compound semiconductors have higher electron mobilities than either Si or Ge and direct band gaps. These properties could enable the fabrication of low power, high-speed n-channel metal oxide semiconductor field effect transistors (MOSFETs) and optoelectronics combining MOS technology with photonics. Since thermal and native oxides formed on III-V surfaces exhibit large current leakage and high densities of trap states, a key to incorporating these materials into advanced devices is the development of processing steps that form stable interfaces with dielectric layers. In this thesis, a processing flow consisting of native oxide removal using HF chemistries and deposition of high dielectric permittivity films using atomic layer deposition was investigated. Understanding the reaction mechanisms of these processes could provide the means of controlling composition and structure, yielding a desired electronic behavior. Quantitative X-ray photoelectron spectroscopy analysis of surfaces was coupled with electrical measurements on MOS capacitors of the interface quality in order to understand the nature of high-k/III-V interface defects and their repair. Ex situ liquid phase HF etching removed InSb, InAs, and InGaAs(100) native oxides and produced an Sb- or As-enriched surface, which oxidized when exposed to air. A 5 to 22 °A thick As- and Sb-rich residual oxide was left on the surface after etching and < 5 min of air exposure. The results showed that group V enrichment originated from the reduction of group V oxides by protons in the solution and the preferential reaction of HF with the group III atom of the substrate. A sub-atmospheric in situ gas phase HF/H2O process removed native oxide from InSb, InAs, and InGaAs(100) surfaces, producing an In or Ga fluoride-rich sacrificial layer. A 50 to 90% oxide removal was achieved and a 10 to 25 °A-thick overlayer consisting of mainly In and Ga fluorides was produced. The composition and morphology of the sacrificial layer were controlled by the partial pressure of H2O as well as the ratio of HF to H2O used. Water played a critical role in the process by directly participating in the etching reaction and promoting the desorption of fluoride etching products. Accumulation of thick fluoride layer at high HF to water partial pressure ratios prevented adsorption and diffusion of etchant to the buried residual oxide. When oxide was removed, HF preferentially reacted with In or Ga atoms from the substrate, enriching the surface with group III fluorides and producing approximately one monolayer of elemental group V atoms at the interface. Interface reactions occurred during atomic layer deposition of Al2O3, in which trimethylaluminum (TMA) removed surface oxides and fluorides. Chemically sharp InSb/Al2O3 and InGaAs/Al2O3 interfaces were achieved for gas phase HF-etched InSb and liquid phase HF-etched InGaAs. A ligand transfer mechanism promotes nucleation of Al2O3 and removal of III-V atoms from the sacrificial oxide and fluoride layers as volatile trimethyl indium, gallium, arsenic, and antimony. These reactions have been explained by the relative bond strength of surface and precursor metal atoms with O and F. Interaction of a InSb(100) surface with TiCl4 as a model for metal halide ALD precursors showed that similar ligand transfer reactions occured. Adsorbed chlorine from the dissociative adsorption of TiCl4 on the InSb surface at elevated temperature, however, preferentially etched In atoms from the substrate and produced a roughened surface. The quality of InGaAs/Al2O3 interfaces prepared by solvent cleaning and liquid phase HF were assesed electrically using capacitance-voltage and conductance measurements. Surface recombination velocity (SRV) values were extracted from the measurements to represent the net effect of interface defects, which includes defect density and capture cross section. The InGaAs/Al2O3 interface prepared by solvent cleaning consisted of interfacial native oxides while that etched in liquid phase HF consisted of submonolayer arsenic oxide. The two chemically contrasting interfaces, however, gave similar SRV values of 34.4±3.7 and 28.9±13.4 cm/s for native oxide and liquid phase HF prepared samples, respectively. This suggests that the presence or absence of oxides was not the only determining factor. Post Al2O3 deposition annealing in forming gas and NH3 ambient significantly improved the electrical quality for both surfaces, as shown by SRV values between 1 to 4 cm/s which is comparable to that of an ideal H-terminated Si surface. XPS analysis showed that the contribution from elemental As and Ga2O3 at the interface of both surfaces increased after annealing in forming gas and NH3, likely due to thermal or hydrogen-induced reaction between interfacial As oxide and Ga atoms in the substrate. There was no correlation between the atomic coverages of interfacial elemental As and oxides to the SRV values. High activity defects at III-V/Al2O3 interfaces are associated with interfacial dangling bonds which were passivated thermally and chemically by annealing in forming gas and NH3.
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WAHI, TAOUFIK. "Mesure des émissions K, satellites, hypersatellites, deux électrons - un photon des éléments légers : carbone, azote et oxygène lors de l'interaction ions multicharges - surface métallique. Etude à haute résolution des transitions satellites K du néon en excitation électronique." Paris, CNAM, 1996. http://www.theses.fr/1996CNAM0238.
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Cette thèse présente les premières mesures, du rapport de branchement et des énergies de transition des émissions deux électrons - un photon et hypersatellites, dans des interactions d'ions nus de carbone, de l'azote et de l'oxygène avec une surface métallique. Ces mesures ont été effectuées par spectrométrie x a cristal plan dans la gamme (200-1500 EV). En plus des corrections relatives aux distorsions instrumentales, qui ont été obtenues par la caractérisation précise du spectromètre a cristal plan utilise (efficacité et fonction d'appareil), la comparaison de nos mesures avec les nombreuses approches théoriques, qui ne traitent que des cas particuliers (configurations initiales de type 2s#22p#m), a nécessité une correction théorique liée a l'estimation de l'influence possible, sur le rapport de branchement mesure, des sous-niveaux 2s et 2p dans les différents états de charge k#2l#n réellement crées lors des expériences. On a pu montrer que par la présence de ces divers états de charge, le rapport de branchement mesure peut diminuer de façon conséquente, en particulier pour les éléments de z<10, empêchant ainsi toute comparaison directe avec des rapports théoriques spécifiques. Cette dernière correction a été possible a l'aide d'une approche théorique que nous avons developpee, combinée avec une détermination expérimentale de la distribution des états de charge k#2l#n initiaux. Les résultats obtenus, énergies de transition et rapports de branchement dont on a pu confirmer la variation en z#-#2, sont en bon accord avec les prédictions théoriques. L'étude a haute résolution des satellites kl#1 du néon en excitation électronique, analyses avec un spectromètre a cristal courbe de béryl (géométrie Johann) fait aussi partie des travaux de cette thèse. Nos objectifs dans cette étude étaient, l'étalonnage du spectromètre a 850 EV et la vérification expérimentale de l'hypothèse statistique de la distribution des configurations 2s#22p#5 et 2s2p#6 de l'état kl#1 du néon. Cette hypothèse importante s'implique dans la méthode corrective concernant les rapports de branchement. Grâce a la haute résolution (1400 à 850 EV) atteinte, les résultats obtenus permettent de confirmer la distribution statistique des configurations dans l'état kl#1 pour ce mode d'excitation.
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Yoldas, Mine. "Predicting The Effect Of Hydrophobicity Surface On Binding Affinity Of Pcp-like Compounds Using Machine Learning Methods." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613215/index.pdf.
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This study aims to predict the binding affinity of the PCP-like compounds by means of molecular hydrophobicity. Molecular hydrophobicity is an important property which affects the binding affinity of molecules. The values of molecular hydrophobicity of molecules are obtained on three-dimensional coordinate system. Our aim is to reduce the number of points on the hydrophobicity surface of the molecules. This is modeled by using self organizing maps (SOM) and k-means clustering. The feature sets obtained from SOM and k-means clustering
are used in order to predict binding affinity of molecules individually. Support vector regression and partial least squares regression are used for prediction.
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Krack, Susannah. "Effect of growth phase and metabolic activity on the surface charge of Escherichia coli K-12 and on its adhesion to quartz and lepidocrocite." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26947.
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There are a number of bacteria associated with livestock, one of which is Escherichia coli 157:H7, a pathogenic bacterium often found associated with animal feces, which has the potential to contaminate groundwater in many rural areas. Adhesion onto soil particles is also an important biogeochemical process controlling bacterial transport that is influenced by a number of interrelated variables including pH, ionic strength, solution chemistry, soil mineralogy, bacterial growth phase and metabolic activity. The main objectives of this thesis were to first assess the surface reactivity of E. coli K-12 (a model non-pathogenic bacterium) as a function of bacterial growth phase and activity and second, to determine the extent of E. coli adhesion to quartz and Fe-oxide, two common soil minerals, as a function of pH, using batch experiments. The titration results showed that lepidocrocite had the highest buffering capacity, then bacteria, and quartz the lowest. (Abstract shortened by UMI.)
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Fischer, Sybille [Verfasser], Johannes [Akademischer Betreuer] Barth, and Ulrich K. [Akademischer Betreuer] Heiz. "Combined STM and X-ray spectroscopy study of surface-confined biologically relevant molecules / Sybille Fischer. Gutachter: Ulrich K. Heiz ; Johannes Barth. Betreuer: Johannes Barth." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1036495043/34.
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Pfister, Lena [Verfasser], and Christoph K. [Akademischer Betreuer] Thomas. "Improving our Understanding of the Atmospheric Weak-wind Boundary Layer using Spatially Explicit Observations near the Ground Surface / Lena Pfister ; Betreuer: Christoph K. Thomas." Bayreuth : Universität Bayreuth, 2020. http://d-nb.info/1238143474/34.
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Wu, Dongping. "Novel concepts for advanced CMOS : Materials, process and device architecture." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3805.
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The continuous and aggressive dimensional miniaturization ofthe conventional complementary-metal-oxide semiconductor (CMOS)architecture has been the main impetus for the vast growth ofIC industry over the past decades. As the CMOS downscalingapproaches the fundamental limits, unconventional materials andnovel device architectures are required in order to guaranteethe ultimate scaling in device dimensions and maintain theperformance gain expected from the scaling. This thesisinvestigates both unconventional materials for the gate stackand the channel and a novel notched-gate device architecture,with the emphasis on the challenging issues in processintegration.
High-κ gate dielectrics will become indispensable forCMOS technology beyond the 65-nm technology node in order toachieve a small equivalent oxide thickness (EOT) whilemaintaining a low gate leakage current. HfO2and Al2O3as well as their mixtures are investigated assubstitutes for the traditionally used SiO2in our MOS transistors. These high-κ filmsare deposited by means of atomic layer deposition (ALD) for anexcellent control of film composition, thickness, uniformityand conformality. Surface treatments prior to ALD are found tohave a crucial influence on the growth of the high-κdielectrics and the performance of the resultant transistors.Alternative gate materials such as TiN and poly-SiGe are alsostudied. The challenging issues encountered in processintegration of the TiN or poly-SiGe with the high-k are furtherelaborated. Transistors with TiN or poly-SiGe/high-k gate stackare successfully fabricated and characterized. Furthermore,proof-of-concept strained-SiGe surface-channel pMOSFETs withALD high-κ dielectrics are demonstrated. The pMOSFETs witha strained SiGe channel exhibit a higher hole mobility than theuniversal hole mobility in Si. A new procedure for extractionof carrier mobility in the presence of a high density ofinterface states found in MOSFETs with high-κ dielectricsis developed.
A notched-gate architecture aiming at reducing the parasiticcapacitance of a MOSFET is studied. The notched gate is usuallyreferred to as a local thickness increase of the gatedielectric at the feet of the gate above the source/drainextensions. Two-dimensional simulations are carried out toinvestigate the influence of the notched gate on the static anddynamic characteristics of MOSFETs. MOSFETs with optimizednotch profile exhibit a substantial enhancement in the dynamiccharacteristics with a negligible effect on the staticcharacteristics. Notched-gate MOSFETs are also experimentallyimplemented with the integration of a high-κ gatedielectric and a poly-SiGe/TiN bi-layer gate electrode.
Key words:CMOS technology, MOSFET, high-κ, gatedielectric, ALD, surface pre-treatment, metal gate, poly-SiGe,strained SiGe, surface-channel, buried-channel, notchedgate.
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Maillart, Emmanuel. "IMAGERIE PAR RESONANCE DES PLASMONS DE SURFACE POUR L'ANALYSE SIMULTANEE DE MULTIPLES INTERACTIONS BIOMOLECULAIRES EN TEMPS REEL." Phd thesis, Université Paris Sud - Paris XI, 2004. http://tel.archives-ouvertes.fr/tel-00006480.
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Les besoins actuels grandissants pour l'analyse des interactions biomoléculaires nécessitent le développement de systèmes automatisés à forte capacité et haut débit comme la microscopie de fluorescence qui reste une méthode de prédilection. Bien que les méthodes directes (sans marquage des molécules à analyser) présentent une sensibilité plus faible que celles utilisant des marqueurs, leurs nombreux avantages (suivi en temps réel, préparation simplifiée des échantillons) sont des atouts d'importance pour l'analyse quantitative des interactions biomoléculaires. En outre, l'imagerie en résonance des plasmons de surface permet de mesurer simultanément de nombreuses interactions comme les méthodes avec marqueurs. Pour élaborer un tel dispositif, nous avons d'abord identifié les différents paramètres critiques, susceptibles d'être améliorés, comme la nature de la couche métallique. L'utilisation du capteur ainsi développé repose en grande partie sur la chimie de surface: nous avons choisi la synthèse électrochimique de films de polypyrrole qui permet, de manière contrôlée et structurée, une fonctionnalisation simple et robuste de plots contenant diverses molécules. Parallèlement, nous avons développé un programme d'acquisition d'images dont le traitement permet de suivre en temps réel les réactions biomoléculaires sur chaque plot et d'en extraire constantes d'association, de dissociation et d'affinité entre molécules. Enfin, nous avons démontré les possibilités d'application de ce système à l'étude de maladies héréditaires ou du cancer à travers des interactions ADN/ADN (K-ras), ADN/protéines (p53), protéines/protéines (hCG) et oligosaccharides/protéines (HP6/SDF-1).
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Thämer, Martin Georg [Verfasser], Ulrich K. [Akademischer Betreuer] Heiz, Michael [Akademischer Betreuer] Moseler, and Reinhard [Akademischer Betreuer] Nießner. "Linear and Nonlinear Surface Spectroscopy of Supported Size Selected Metal Clusters and Organic Adsorbates / Martin Thämer. Gutachter: Michael Moseler ; Reinhard Nießner. Betreuer: Ulrich K. Heiz." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1021219215/34.
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Araújo, Manoel Silvino Batalha de. "Extensão de GENSMAC para escoamentos de fluidos governados pelos modelos integrais Maxwell e K-BKZ." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-08022007-151417/.
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Este trabalho tem como objetivo desenvolver um método numérico para simular escoamentos incompressíveis, isotérmicos, confinados ou com superfícies livres, de fuidos viscoelásticos governados pelos modelos integrais de Maxwell e K-BKZ (Kaye-Bernstein, Kearsley e Zapas). A técnica numérica apresentada é uma extensão do método GENSMAC (Tomé McKee - J. Comp. Phys., (110), pp 171--186, 1994 ) para a solução das equações de conservação, juntamente com as equações constitutivas integrais de Maxwell e K-BKZ. As equações governantes são resolvidas pelo método de diferenças finitas em uma malha deslocada. O tensor de Finger, B_t\'(t) é calculado com base nas idéias do método de campos de deformação (Peters et al. - J. Non-Newtonian Fluid Mech. (89), de maneira que não há a necessidade de seguir a trajetória da partícula de fuido para descrever a história de deformação da partícula. Uma abordagem diferente para a discretização do instante passado é utilizada e o tensor de Finger e o tensor das tensões são calculados utilizando um método de segunda ordem. A validação do método numérico descrito nesse trabalho foi feita utilizando o escoamento em um canal bidimensional e a solução numérica obtida para a velocidade e para as componentes de tensão com o modelo de Maxwell foram comparadas com as respectivas soluções analíticas no estado estacionário, mostrando excelente concordância. Os resultados numéricos para a simulação do escoamento em uma contração planar 4 : 1 mostraram bons resultados, tanto qualitativos quanto quantitativos, quando comparados com os resultados experimentais de Quinzani et al. ( J. Non-Newtonian Fluid Mech. (52), pp 1?36, 1994 ). Além disso, utilizando os modelos Maxwel e K-BKZ, o escoamento em uma contração planar 4 : 1 foi simulado para vários números de Weissenberg e os resultados obtidos estão de acordo com os encontrados na literatura. Resultados numéricos de escoamentos com superfícies livres modelados pelas equações integrais de Maxwell e K-BKZ são apresentados. Em particular, a simulação numérica do jato oscilante para diferentes números de Weissenberg e diferentes números de Reynolds é apresentada.The aim of this work is to develop a numerical technique for simulating incompressible, isothermal, free surface (also con¯ned) viscoelastic flows of fuids governed by the integral models of Maxwell and K-BKZ (Kaye-Bernstein, Kearsley and Zapas). The numerical technique described herein is an extension of the GENSMAC method (Tome and McKee, J. Comput. Phys., 110, pp. 171-186, 1994) to the solution of the momentuum and mass conservation equations together with the integral constitutive Maxwell and K-BKZ equations. The governing equations are solved by the finite difference method on a staggered grid using a Marker-and-Cell approach. The fluid is represented by marker particles on the fluid surface only. This provides the visualization and location of the fluid free surface so that the free surface stress conditions can be applied. The Finger tensor Bt0(t) is computed using the ideias of the deformation fields method (Peters et al. J. Non-Newtonian Fluid Mech., 89, pp. 209-228, 2001) so that it is not necessary to track a fluid particle in order to calculate its deformation history. However, in this work modifcations to the deformation fields method are introduced: the past time is discretized using a different formula, the Finger tensor Bt0(x; t) is obtained by a second order method and the stress tensor ? (x; t) is computed by a second order quadrature formula. The numerical method presented in this work is validated by simulating the flow of a Maxwell fluid in a two-dimensional channel and the numerical solutions of the velocity and the stress components are compared with the respective analytic solutions providing a good agreement. Further, the flow through a 4:1 planar contraction of a specific fuid studied experimentally by Quinzani et al. (J. Non-Newtonian Fluid Mech., 52, pp. 1-36, 1994) was simulated and the numerical results were compared qualitatively and quantitatively with the experimental results and very good agreement was obtained. The Maxwell and the K-BKZ models were applied to simulate the 4:1 planar contraction problem using various Weissenberg numbers and the numerical results were in agreement with those published in the literature. Finally, numerical results of free surface flows using the Maxwell and K-BKZ integral constitutive equations are presented. In particular, the numerical simulation of jet buckling using several Weissenberg numbers and various Reynolds numbers are presented
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Renaudot, Raphaël. "Conception, fabrication de puces microfluidiques à géométrie programmable et reconfigurable reposant sur les principes d’électromouillage sur diélectrique et de diélectrophorèse liquide." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY080/document.
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Dans le domaine des Lab-on-a-chip (LOC), la géométrie des canaux d'une puce microfluidique est souvent spécifique à la réalisation d'un protocole donné. La géométrie d'une puce est définie à l'étape de conception, avant les étapes de fabrication (généralement longues et coûteuses), et ne peut être modifiée a posteriori. Ce constat devient problématique lorsque la géométrie ne répond pas de façon satisfaisante au cahier des charges et qu'un nouveau lot de fabrication doit être démarré afin de redimensionner la puce. Pour pallier cet inconvénient, nous proposons de développer des puces microfluidiques génériques dont la géométrie est programmable et reconfigurable. Ce concept s'appuie largement sur les deux techniques de microfluidique digitale, l'électromouillage sur diélectrique (EWOD) et la diélectrophorèse liquide (LDEP). La première voie d'étude se concentre sur la technique de microfluidique LDEP. Tout d'abord, un modèle électromécanique, décrivant les comportements des liquides lors d'actionnements par LDEP ou EWOD, est établi. Ce modèle sert ensuite de base pour la conception et la fabrication de designs LDEP. Ces derniers sont testés afin d'identifier les géométries et les empilements technologiques, offrant des actionnements LDEP optimisés. L'étude, qui prend en compte un grand nombre de paramètres, montre que, avec des configurations et conditions spécifiques, les actionnements de liquide par LDEP offrent des performances égales, a minima, sur certains points, et supérieures sur d'autres par rapport à l'ensemble des études reportées dans la littérature. Enfin, un protocole de fonctionnalisation de surface par des spots de polymère de quelques microns à plusieurs dizaines de microns de diamètre, utilisant la technologie LDEP, est décrit. Cette méthode est susceptible de concurrencer directement les méthodes de fonctionnalisation classiques. La seconde voie d'étude traite du concept de géométrie programmable et reconfigurable, à l'aide de plateformes microfluidiques couplant les effets LDEP et EWOD. Dans un premier temps, les plateformes en configuration " ouverte " permettent de produire des moules à géométrie programmable pour la réalisation de puces microfluidiques en PDMS. Les résultats de cette étude prometteuse aboutissent, entre autres, à la réalisation de géométries de canaux complexes et typiques dans le domaine de la microfluidique (jonctions en " T " et valves de type " Quake "). Dans un second temps, les résultats les plus aboutis de ce manuscrit sont exposés à propos du concept de géométrie programmable et reconfigurable en utilisant de la paraffine. Un protocole spécifique, exploitant judicieusement les déplacements de liquides par EWOD et LDEP, donne lieu à la fabrication d'un grand nombre de puces microfluidiques, comportant des géométries de canaux complexes et variées. Dans les deux cas, un grand nombre de géométries peut être généré a à partir d'une seule plateforme microfluidique digitale générique. Les résultats obtenus ouvrent des perspectives de travail originales et prometteuses, dont certaines d'entre elles sont abordées en marge des objectifs initiaux. La première se trouve dans la continuité du concept de géométrie programmable et reconfigurable, en proposant une technologie à bas coût (substrat souple en Kapton et impression d'électrodes avec de l'encre conductrice). La seconde perspective instruit la compatibilité des technologies comportant des structures résonantes de type MEMS et des structures métalliques LDEP (en polysilicium) à l'échelle submicroniqueIn the field of lab-on-a-chip (LOC) systems, the channel geometry of a microfluidic chip is often specific to perform a given protocol. The chip geometry is hence defined at the design step, before the fabrication steps (generally time consuming and expensive) and cannot be thereafter modified. This fact becomes an issue when the geometry does not fit satisfactorily to the specifications and a new batch of fabrication has to be started, to size afresh the microfluidic chip. To overcome this inconvenient we propose to develop a new generation of microfluidic chips with a programmable and reconfigurable geometry. This concept is widely based on both digital microfluidic techniques, the electrowetting on dielectrics (EWOD) and the liquid dielectrophoresis (LDEP) actuations. The first investigation is focused on the microfluidic technique LDEP. First, an electromechanical model for liquids behaviours during a EWOD or LDEP actuation is established. This model is then used as a basis for the LDEP patterns design and fabrication. The LDEP patterns are tested to identify the geometries and dielectric layers stacks which give optimized LDEP actuations. By taking into account a broad parameters range, the study shows that, within a precise setup and specific conditions, the LDEP actuations can have equal performances at the minimum, or better performances than those reported in the overall scientific literature until now. Finally, a surface functionalization protocol by polymer spots (diameter size ranging from a few microns to several dozens of microns) utilizing the LDEP technology is described. This method is likely to compete directly with the standard functionalization tools. The second investigation is dealing with the programmable and reconfigurable geometry concept, thanks to microfluidic platforms which get together both EWOD and LDEP technologies on a same component. Firstly, the microfluidic platform in a single plate configuration allows providing master molds with a programmable geometry for the PDMS microfluidic chip fabrication. The results about this promising study lead to the processing of complex channels geometries, typically used in the microfluidic field. Secondly, the more exciting results are exposed about the programmable and reconfigurable microfluidic concept, by using advantageously the paraffin material. A specific protocol which takes advantages of LDEP and EWOD liquids displacements produces a lot of various and different microfluidic chips with complex channels shapes. For both applications, a single generic microfluidic platform can generate a wide number of different geometries, which can be modified partially or totally thereafter. The obtained results open up novel and promising work prospects, which one of them are approached on the fringe of the initial purposes. The first one belongs to the continuity of the programmable and reconfigurable by suggesting a low cost technology based on flexible Kapton substrate and inkjet printing of silver nanoparticules. The second one investigates the technologies compatibility between MEMS/NEMS resonating structures and LDEP metal structures (in polysilicon) at the submicronic scale
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Usman, Muhammad. "Impact of Ionizing Radiation on 4H-SiC Devices." Doctoral thesis, KTH, Integrerade komponenter och kretsar, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-60763.
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Electronic components, based on current semiconductor technologies and operating in radiation rich environments, suffer degradation of their performance as a result of radiation exposure. Silicon carbide (SiC) provides an alternate solution as a radiation hard material, because of its wide bandgap and higher atomic displacement energies, for devices intended for radiation environment applications. However, the radiation tolerance and reliability of SiC-based devices needs to be understood by testing devices under controlled radiation environments. These kinds of studies have been previously performed on diodes and MESFETs, but multilayer devices such as bipolar junction transistors (BJT) have not yet been studied. In this thesis, SiC material, BJTs fabricated from SiC, and various dielectrics for SiC passivation are studied by exposure to high energy ion beams with selected energies and fluences. The studies reveal that the implantation induced crystal damage in SiC material can be partly recovered at relatively low temperatures, for damag elevels much lower than needed for amorphization. The implantation experiments performed on BJTs in the bulk of devices show that the degradation in deviceperformance produced by low dose ion implantations can be recovered at 420 oC, however, higher doses produce more resistant damage. Ion induced damage at the interface of passivation layer and SiC in BJT has also been examined in this thesis. It is found that damaging of the interface by ionizing radiation reduces the current gain as well. However, for this type of damage, annealing at low temperatures further reduces the gain. Silicon dioxide (SiO2) is today the dielectric material most often used for gate dielectric or passivation layers, also for SiC. However, in this thesis several alternate passivation materials are investigated, such as, AlN, Al2O3 and Ta2O5. These materials are deposited by atomic layer deposition (ALD) both as single layers and in stacks, combining several different layers. Al2O3 is further investigated with respect to thermalstability and radiation hardness. It is observed that high temperature treatment of Al2O3 can substantially improve the performance of the dielectric film. A radiation hardness study furthermore reveals that Al2O3 is more resistant to ionizing radiation than currently used SiO2 and it is a suitable candidate for devices in radiation rich applications.QC 20120117
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Candezano, Miguel Antonio Caro. "Desenvolvimento de esquema upwind para equações de conservação e implementação de modelagens URANS com aplicação em escoamentos incompressíveis." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-18022013-112410/.
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Nesta tese é apresentado um esquema novo de alta resolução upwind (denominado TDPUS-C3) para reconstrução de fluxos numéricos para leis de conservação não lineares e problemas relacionados em DFC. O esquema é baseado nos critérios de estabilidade CBC e TVD e desenvolvido utilizando condições de diferenciabilidade \'C POT. 3\'. Além disso, é realiozada a implementação da associação do esquema TDPLUS-C3 com a modelagem de turbulência RNG \'\\kappa - \\epsilon\'. O propósito é obter soluções numéricas de sistemas hiperbólicos de leis de conservação para dinâmica dos gases e equações de Navier-Stokes para escoamento incompreensível de fluidos newtonianos e não newtonianos (viscoelásticos). Fazendo o uso do esquema TDPUS-C3, a precisão global dos métodos numéricos é verificada acessando o erro em problemas teste (benchmark) 1D e 2D. Um estudo comparativo entre os resultados do esquema TDPUS-C3 e os esquemas upwind convencionais para leis de conservação hiperbólicas complexas é também realizado. A Associação das modelagens numéricas (upwinding mais RNG \'\\kappa - \\epsilon\') é , então, examinada na simulação de escoamentos turbulentos de fluidos newtonianos envolvendo superfícies livres móveis, usando a metodologia URANS. No geral, em termos do comportamento global, concordância satisfatória é observadaIn this thesis, a new high-resolution upwind scheme (named TDPUS-C3) for reconstruction of numerical fluxes for nonlinear conservation laws and related CFD problems in presented. The scheme is based on CBC and TVD stability criteria and developed by employing differentiability condictions (\'C POT. 3\'). In additon, the implementation of an association of the TDPUS-C3 scheme with the RNG \'\\kappa - \\epsilon\' turbulence modelling is also performed. The purpose is to obtain numerical solutions of systems of hyperbolic conservation laws for gas dynamics and Navier-Stokes equations for incompressible flow of Newtonian and non-Newtonian (viscoelstic) fluids. By using the TDPUS-C3 scheme, the global accuracy of the numerical methods is verified by assessing the error on 1D and 2D benchmark test cases. A comparative study between the TDPUS-C3 scheme and convectional upwind schemes to solve standard and complex hyperbolic conservation laws is also accomplished. The association of the numerical modelling (upwinding plus RNG \'\\kappa - epsilon\') is then examined in the simulation of turbulent Newtonian fluid flows involving moving free surfaces, by using URANS methodology. Overall, satisfactory agreement is found in terms of the overall behaviour
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Schamm, Sylvie. "Sur l'élaboration des composites SiC/Al par le procédé au K2ZrF6 bases physico-chimiques et incidence sur la résistance des fibres." Phd thesis, Bordeaux 1, 1989. https://tel.archives-ouvertes.fr/tel-00374529.
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Amélioration de la mouillabilité des fibres de SiC par les alliages d'aluminium grace à un traitement de surface par une solution aqueuse saturée de K₂ZrF₆ à température proche de l'ébullition. Analyse des phénomènes responsables des cette amélioration et de leur influence sur la résistance à la rupture des fibres.
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Kaposi, Tobias [Verfasser], Johannes [Akademischer Betreuer] [Gutachter] Barth, and Ulrich K. [Gutachter] Heiz. "A Compact and Versatile Electrospray Ion Beam Deposition Setup : Advanced Sample Preparation for Experiments in Surface Science / Tobias Kaposi ; Gutachter: Ulrich K. Heiz, Johannes Barth ; Betreuer: Johannes Barth." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1136422641/34.
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Liang, Sijia [Verfasser], Roger [Gutachter] Wördenweber, Markus [Gutachter] Grüninger, and Joachim [Gutachter] Hemberger. "Surface Acoustic Waves in Strain-Engineered Thin (K,Na)NbO3 Films: From Basic Research to Application in Molecular Sensing / Sijia Liang ; Gutachter: Roger Wördenweber, Markus Grüninger, Joachim Hemberger." Köln : Universitäts- und Stadtbibliothek Köln, 2021. http://d-nb.info/1229616705/34.
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Robertson, Francis. "An experimental investigation of the drag on idealised rigid, emergent vegetation and other obstacles in turbulent free-surface flows." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/an-experimental-investigation-of-the-drag-on-idealised-rigid-emergent-vegetation-and-other-obstacles-in-turbulent-freesurface-flows(07165357-67da-461d-a6a2-ed4970e2cb0c).html.
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Vegetation is commonly modelled as emergent arrays of rigid, circular cylinders. However, the drag coefficient (CD) of real stems or trunks is closer to that of cylinders with a square cross-section. In this thesis, vegetation has been idealised as square cylinders in laboratory experiments with a turbulence intensity of the order of 10% which is similar to that of typical river flows. These cylinders may also represent other obstacles such as architectural structures. This research has determined CD of an isolated cylinder and cylinder pairs as a function of position as well as the average drag coefficient (CDv) of larger arrays. A strain gauge was used to measure CD whilst CDv was computed with a momentum balance which was validated by strain gauge measurements for a regularly spaced array. The velocity and turbulence intensity surrounding a pair of cylinders arranged one behind the other with respect to mean flow (in tandem) were also measured with an Acoustic Doppler Velocimeter. The isolated cylinder CD was found to be 2.11 in close agreement with other researchers. Under fixed flow conditions CD for a cylinder in a pair was found to be as low as -0.40 and as high as 3.46 depending on their relative positioning. For arrays, CDv was influenced more by the distribution of cylinders than the flow conditions over the range of conditions tested. Mean values of CDv for each array were found to be between 1.52 and 3.06. This new insight therefore suggests that CDv for vegetation in bulk may actually be much higher than the typical value of 1 which is often assumed to apply in practice. If little other information is available, a crude estimate of CDv = 2 would be reasonable for many practical applications. The validity of a 2D realizable k-epsilon turbulence model for predicting the flow around square cylinders was evaluated. The model was successful in predicting CD for an isolated cylinder. In this regard the model performed as well as Large Eddy Simulations by other authors with a significant increase in computational efficiency. However, the numerical model underestimates CD of downstream cylinders in tandem pairs and overestimates velocities in their wake. This suggests it may be necessary to expand the model to three-dimensions when attempting to simulate the flow around two or more bluff obstacles with sharp edges.
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Coanga, Jean-Maurice. "Caractéristiques vibrationnelles du chlorure de nitryle, du diméthyl-éther et de l'oxyde d'éthylène absorbés sur la surface de la glace ou piégés dans son volume entre 10 et 170 K : Etude de leur photodissociation à 30 K en matrices, phase solide et dans la glace." Paris 6, 2003. http://www.theses.fr/2003PA066062.
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Coste, Antoine. "Nanocristaux semi-conducteurs : couplage avec des structures plasmoniques à 4 K et effets collectifs." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLV066/document.
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Les nanocristaux colloïdaux sont des fluorophores semi-conducteurs de taille nanométrique. Fluorescents à température ambiante et synthétisés par voie chimique, ces nanoémetteurs représentent d'excellents candidats pour divers domaines d'application tels que l'éclairage, le marquage biologique ou le photovoltaïque.Mon travail expérimental, s'inscrit dans le développement de ces nanoémetteurs via deux approches différentes : leur couplage avec des nanostructures plasmoniques à 4K et la mise en place de régime d'émission collective.Dans un premier temps, nous avons étudié le couplage de nancoristaux individuels avec des films d'or plan dans le but de réduire les pertes par effet Joule. Tout d'abord, nous nous sommes intéressés à l'influence de la température sur ce couplage. A partir d'expériences de photoluminescence et de simulations numériques effectuées par Gérard Colas des Francs du LCIB, nous avons pu mesurer et simuler une forte diminuation de l'accélération du temps caractéristique d'émission des nanocristaux lorsque la température passe de 300K à 4K. Cette diminution est directement liée à une importante diminution des pertes ohmiques des couches d'or. L'efficacité quantique des nanocristaux est ainsi augementée d'un facteur 3. Ensuite, nous avons étudié l'influence de la cristallinité de l'or sur ce couplage. A nouveau une forte réduction de l'accélération de l'émission des nanocristaux a été mesurée sur or cristallin en comparaison avec des couches d'or amorphe. Ces mesures laissent de nouveau présager une réduction des pertes par effet Joule ainsi qu'une augmentation d'au moins un facteur deux de l'efficacité quantique des nanocristaux.Dans un second temps, nous avons effectué les premières caractérisations d'agrégats de nanocristaux enrobés dans une coquille de silice. A température ambiante, nous avons mis en évidence la présence d'interaction de type FRET entre les nanocristaux émettant dans le bleu et les nanocristaux émettant dans le rouge. Cette interaction permet ainsi une accélération de l'émission globale des agrégats. A 4K, nous avons observé une modification de la dynamique d'émission des agrégats avec l'apparition de deux échelles de temps différentes. Pour les temps courts, la dynamique d'émission est accélérée et est régie par la recombinaison de l'exciton. Pour les temps longs, la dynamique d'émission est régie par une loi de puissance traduisant ainsi l'apparition de temps caractéristiques d'émission extrêmement longsColloidal semiconductor nanocrystals are fluorescent semiconductors with a nanometric size. Bright at room temperature and chemically synthesized, nanocrystals are interesting candidates for differents applications as lighting, biological labeling or photovoltaic.My experimental work, is part of the development of these emitters by two differents approaches : coupling with plasmonic structures at 4,K and formation of collective emission.First, we studied the coupling between single nanocrystals and a flat gold film in order to decrease the optical losses. To begin we studied the influence of the temperature. With some photoluminescence measurements and some simulations, we show significant decrease of the enhancement of the photoluminescence decay rate at 4,K. This reduction is linked to the decrease of optical losses. Then, we studied the influence of crystallinity of gold. We show again an important reduction of enhancement of the photoluminescence decay rate with crystalline gold compared to amorphous layer.Second, we investigated the optical properties of compact nanocrystal clusters encapsulated in a silica shell. At room temperature, we observed an enhancement of the photoluminescence decay rate through Förster resonance energy transfer (FRET). At 4K, we measured an important variation of the emission dynamic with emergence of two times scales. At short time scale, emission is accelerated and governed by the exciton recombination. At long time scale, the decay is governed by power law showing the emergence of long-lived states
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AGHLAL-HADDED, MALIKA. "Proprietes physicochimiques du nitrate d'ethylammonium fondu et de ses melanges avec l'eau a 298 k : comportement des electrolytes dilues dans ces milieux." Paris 6, 1988. http://www.theses.fr/1988PA066283.
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L'utilisation d'un sel a bas point de fusion (14**(o)c), le nitrate d'ethylammonium, miscible a l'eau en toute proportion permet de suivre les proprietes thermodynamiques de milieux salins entre l'eau pure et le sel fondu. Le modele propose, permet de preciser les differents roles joues par les anions et les cations en solution. Ce sont les cations qui perturbent les proprietes de l'eau dans la solution
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Cattani, Fanny. "Définition d’une collection de minéraux de référence afin de développer et de calibrer une méthode de datation in-situ adaptée à la surface de Mars." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS002/document.
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La détermination d’âges absolus est nécessaire pour calibrer la chronologie relative martienne basée sur la densité de cratères d’impact. Dans ce but, nous avons développé au laboratoire GEOPS un prototype pour la datation in-situ des surfaces planétaires par la méthode K-Ar. Cette installation, financée dans le cadre d’un programme de recherche CNES-CNRS, est basée sur l’ablation laser permettant la vaporisation d’un volume reproductible de roche. La composition chimique de la matière ablatée, et en particulier la teneur en potassium (K), est estimée par Laser Induced Breakdown Spectroscopy (LIBS) et la quantité d’argon (Ar) libérée est mesurée par spectrométrie de masse quadripolaire (QMS). La détermination de l’âge K-Ar requiert en outre la quantification précise de la masse d’échantillon ablatée. Après une phase importante de développement instrumental visant à améliorer la précision et la sensibilité de la technique, nos efforts ont porté sur la calibration du dispositif. Pour ce faire, une collection d’échantillons de référence (micas, feldspaths, amphibolite, basaltes) a été réalisée et analysée (chimie totale et mesures d’âges par les techniques K-Ar et ⁴⁰Ar/³⁹Ar classiques). Ces échantillons présentent des teneurs en K de 0,15 à 11% et des teneurs de 1 à 100x10¹⁴ atomes d’⁴⁰Ar* par gramme, équivalent à des basaltes martiens âgés de 700 Ma à 3 Ga pour 0,4%K. Les résultats obtenus ont permis de définir une corrélation entre le temps d'ablation et la masse ablatée selon le type de phase minérale ciblée. Afin de valider cette corrélation, des mesures ont été menées « en aveugle » sur plusieurs échantillons, en particulier un basalte microlitique (Trapps de Viluy) similaire aux basaltes composant la surface de Mars. L’âge K-Ar in-situ de 401 ± 41 Ma obtenu par notre approche est consistant avec l’âge de 381 ± 5 Ma mesuré indépendamment sur populations de minéraux. Plus généralement, cette étude a permis d’obtenir des âges K-Ar mesurés par notre méthode de datation in-situ avec une incertitude inférieure à 15%, y compris sur des roches peu potassiques et relativement jeunes comparées aux roches martiennesAbsolute age determination is necessary to check and calibrate the relative Martian chronology presently available from meteoritic crater counting. For this purpose, we have developed an in-situ K-Ar dating prototype for planetary surfaces at GEOPS laboratory. This instrument, supported by a CNES-CNRS research program, is a laser ablation-based system built to vaporize a reproducible volume of rock or mineral. It quantifies potassium content (K) by laser-induced breakdown spectroscopy (LIBS) and argon (Ar) by quadrupole mass spectrometry (QMS). The K-Ar age determination also requires accurate quantification of the ablated sample mass. Following an important period of experimental set-up development to improve precision, accuracy and sensitivity of the technique, our efforts focused on the calibration of the different parts of this instrument. To that purpose, a collection of reference samples (micas, feldspars, amphibolite, basalts) was done and analyzed (total chemistry and age measurements by K-Ar and ⁴⁰Ar/³⁹Ar conventional techniques). These samples show a K content between 0,15 and 11% and an Ar content between 1 and 100x10¹⁴ ⁴⁰Ar* atoms per gram, corresponding to Martian basalt from 700 Ma to 3 Ga for 0.4% K. The results obtained evidence a correlation between the ablation time and the ablated mass depending on the mineral phase analyzed. In order to check this correlation, measurements were conducted on several samples, in particular a microlitic basalt (Viluy basalt) similar to Martian basalts. The K-Ar in-situ age of 401 ± 41 Ma obtained by our approach is consistent with the age of 381 ± 5 Ma measured indepedently on mineral populations. More generally, this study allows to obtain K-Ar ages measured by our in-situ dating method with uncertainties lower than 15%, on relatively low-K and young samples compared to Martian rocks
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Lamirault, Sylvie. "Comportement du cuivre dans les melanges hf-mf (m = k ou nh : :(4)) fondus utilises pour l'obtention electrolytique du fluor." Paris 6, 1987. http://www.theses.fr/1987PA066467.
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Etude thermodynamique et cinetique de la corrosion electrochimique dans les melanges hf-mf(m=k ou nh::(4)) du cuivre metal entrant, soit pur, soit sous forme d'alliage (monel) dans la construction des cellules industrielles d'electrolyse. Mise en evidence de la formation d'une couche de fluorure de cuivre passivante. Evaluation de l'epaisseur limite de la couche. Etablissement de l'influence de la densite de courant sur le caractere passivant de la couche formee. Proposition d'un mecanisme de corrosion du cuivre
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Brandi, Analice Costacurta. "Estratégias "upwind" e modelagem k-epsilon para simulação numérica de escoamentos com superfícies livres em altos números de Reynolds." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-01122005-170110/.
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Este trabalho é dedicado à análise e implementação de esquemas "upwind" de alta ordem modernos e o modelo de turbulência k-epsilon padrão no Freeflow-2D; um ambiente integrado para simulação numérica em diferenças finitas de problemas de escoamentos incompressíveis com superfícies livres. O propósito do estudo é a simulação de escoamentos de fluidos newtonianos incompressíveis, bidimensionais, confinados e/ou com superfícies livres e a altos valores do número de Reynolds. O desempenho do código Freeflow-2D atual é avaliada na simulação do escoamento numa expansão brusca e de um jato livre incidindo perpendicularmente sobre uma superfície rígida impermeável. O código é então aplicado na simulação de um jato planar turbulento em uma porção de fluido com superfície livre e estacionário. Os resultados numéricos obtidos são comparados com dados experimentais, soluções analíticas e soluções numéricas de outros trabalhos.This work is devoted to the analysis and implementation of modern high-order upwind schemes and the standard k-epsilon turbulence model into the Freeflow-2D; a finite difference integrated environment for the numerical simulation of incompressible free surface flow problems. The purpose of this study is the two-dimensional simulation of high-Reynolds incompressible newtonian confined and/or free surface flows. The performance of the current Freeflow-2D code is assessed by applying it to the simulation of flow over a backward facing step and of an impinging free jet onto an impermeable rigid surface. The code is then applied to a turbulent planar jet into a pool. The numerical results are compared with experimental data, analytical solution, and numerical simulations of other works.
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Galdámez, Edwin Vladimir Cardoza. "Aplicação das técnicas de planejamento e análise de experimentos na melhoria da qualidade de um processo de fabricação de produtos plásticos." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18140/tde-18112002-090421/.
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Experimentos industriais são realizados pelas empresas no intuito de melhorar as características de qualidade dos produtos e processos de fabricação. Nesse sentido, esta dissertação tem como objetivo estudar e aplicar as técnicas de planejamento e análise de experimentos na melhoria da qualidade industrial. Como parte do objetivo, desenvolve-se uma aplicação com as técnicas de planejamento fatorial fracionado '2POT. K-P', metodologia de superfície de resposta e análise de variância, em um processo de moldagem por injeção, utilizado por uma indústria que fabrica e comercializa componentes plásticos usados na construção civil. Com essa pesquisa experimental identificam-se os parâmetros mais importantes da injeção plástica: temperatura da máquina e pressão de injeção. Ao mesmo tempo, determinam-se os níveis ótimos de regulagem desses parâmetros. Assim, com esse estudo, avalia-se o procedimento de implantação das técnicas de experimentação e as dificuldades práticas encontradas, bem como busca-se contribuir na integração entre universidade e empresa.Industrial experiments are made by companies in order to improve the quality characteristics of products and production processes. In this sense, the objective of this dissertation is to study and apply the design of experiments in the industrial quality improvement. In addition, as a part of the objective, an application of the techniques of design Fractional Factorial '2POT. K-P', Analysis of Variance and Response Surface Methodology is done. It is focused in an injection molding process applied by a company, that makes and trades plastic products for the civil construction. Using this experimental study, the most important parameters of plastic injection are identified: melt temperature and injection pressure. At the same time, the optimal levels of adjustment of these parameters are determined. From this study, it is evaluated both the implantation procedures of the designs of experiments as well as the difficulties faced. Also, this study tries to contribute to the university-company relationship.
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Ahner, Nicole. "Wetting Optimized Solutions for Plasma Etch Residue Removal for Application in Interconnect Systems of Integrated Circuits." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-102773.
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In multi-level Co/low-k based interconnect systems of ultralarge-scale integrated electronic devices the removal of plasma etch residues by common plasma cleaning processes has been shown to alter material properties like k-value and leakage current of the low-k dielectric. Besides the development of less damaging plasma processes their substitution by wet cleaning steps is in the focus of research and development. With further decreasing feature dimensions the development of wet cleaning processes has to include wetting issues like the non-wetting of small features due to the surface energy of the liquid or pattern collapse effects of low-k dielectric trenches due to high capillary forces This work at first focuses on the determination of the surface energetic character of common cleaning solutions for PERR and differently etched or ashed low-k dielectric surfaces by contact angle analysis, to outline which combinations of solid and liquid will be critical regarding their wetting behavior. Besides the determination of the wetting behavior the contact angle analysis turned out to be a fast and sensible analytic tool to understand the surface modifications introduced by different plasma processes and can help to understand the mechanisms of plasma damage of low-k dielectric surfaces. The analysis showed that especially polymerizing plasma etch processes produce a low-energetic low-k dielectric surface with a negligible polar energy contributions, which inhibits their wetting by high energetic water based cleaning solutions, which actually are favored by semiconductor manufacturers. The strategy to overcome these wetting issues followed in the present work is the reduction of the surface energy of the cleaning liquids by the application of surfactants. Several types of surfactants have been applied to the cleaning liquids and the compatibility of the surfactant solutions to BEOL materials like low-k dielectrics, copper and diffusion barriers as well as their dynamic behavior has been studied. The analysis showed that choosing the appropriate rinsing solution after the cleaning process is essential to ensure its compatibility to porous low-k dielectrics. Optical, electrical and structural data indicated that DIW rinse in most of the cases was not able to remove residual surfactant species within the material, while for an IPA rinse most of the residual surfactants have been removed. Considering the data received for compatibility to low-k materials, copper and barriers, the dynamic behavior of the surfactant solutions as well as influences of increased bath temperature and long term stability a general advice about surfactant selection and processing of surfactant aided solutions within BEOL is givenIn mehrlagigen Kupfer/low-k basierten Metallisierungssystemen hochintegrierter elektronischer Bauelemente kann die Entfernung von Residuen nach der Plasmastrukturierung des Dielektrikums mittels herkömmlicher Plasmareinigungsprozesse zur Schädigung der Isolatorschicht und damit zum Ansteigen der relativen Dielektrizitätszahl sowie der Leckströme führen. Neben der Entwicklung schädigungsarmer Plasmaprozesse stellt der Ersatz dieser Prozesse durch Nassreinigungsschritte zur Ätzresiduenentfernung eine vielversprechende Alternative dar. Mit stetig abnehmenden Strukturabmaßen ist bei der Entwicklung dieser Nassreinigungsprozesse neben der Materialkompatibilität auch das Benetzungsverhalten der Reinigungsflüssigkeit von entscheidender Bedeutung, da die Oberflächenenergie der Reinigungslösung das Eindringen dieser in kleinste Strukturen verhindern und es durch hohe Kapillarkräfte zum Kollaps von Grabenstrukturen im Dielektrikum kommen kann. In der vorliegenden Arbeit wurde zunächst mittels Kontaktwinkelanalyse die Oberflächenenergie verschieden prozessierter low-k Dielektrikaschichten sowie herkömmlicher Lösungen zur Entfernung von Ätzresiduen untersucht, um hinsichtlich ihres Benetzungsverhaltens besonders kritische Materialkombinationen aufzuzeigen. Neben der Bestimmung des Benetzungsverhaltens hat sich die Kontaktwinkelanalyse zur Oberflächenenergieberechnung als schnelle und empfindliche Methode zur Analyse der Auswirkung von Plasmaprozessen auf die Oberfläche von low-k Dielektrika erwiesen. Die Untersuchungen haben gezeigt, dass besonders polymerisierende Plasmaprozesse eine niederenergetische Oberfläche erzeugen, welche von den derzeit in der Halbleiterfertigung bevorzugten hochenergetischen wasserbasierten Reinigungslösungen nur schlecht benetzt wird. Um diesem Effekt entgegenzuwirken wurde in der vorliegenden Arbeit die Senkung der Oberflächenenergie der Reinigungslösungen durch Zugabe von Tensiden untersucht. Es wurden mehrere Tenside unterschiedlichen Typs den Reinigungsflüssigkeiten zugemischt und die Kompatibilität dieser Lösungen mit low-k Dielektrika, Kupferschichten und Diffusionsbarrieren untersucht sowie ihr dynamisches Verhalten analysiert. Dabei hat sich gezeigt, dass die Auswahl der geeigneten Spüllösung nach dem eigentlichen Reinigungsprozess von entscheidender Bedeutung ist. Optische, elektrische sowie strukturelle Daten deuten darauf hin, dass bei Verwendung einer Spülung mit deionisiertem Wasser in den meisten Fällen Tensidrückstände im porösen Dielektrikum verbleiben. Eine Spülung mit Isopropanol war hingegen in der Lage, einen Großteil dieser Tensidrückstände zu entfernen. Unter Einbeziehung der Daten zur Materialkompatibilität und dem dynamischen Verhalten der Tensidlösungen bei Raumtemperatur und erhöhter Badtemperatur sowie ihrer Langzeitstabilität konnte schließlich eine Prozessempfehlung für die Verwendung der benetzungsoptimierten Reinigungslösungen in der BEOL-Prozessierung gefunden werden
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Heckmann, Jan [Verfasser], Ulrike [Akademischer Betreuer] Woggon, Ulrike [Gutachter] Woggon, Kurt [Gutachter] Busch, and Vasily [Gutachter] Temnov. "Investigations of nonlinear surface-wave phenomena and anisotropic photoluminescence of nano-film structures via two-dimensional k-space spectroscopy / Jan Heckmann ; Gutachter: Ulrike Woggon, Kurt Busch, Vasily Temnov ; Betreuer: Ulrike Woggon." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156014247/34.
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Ding, Li. "Optical Anisotropy and Molecular Orientation of CuPc Films and Optical Properties of Ultra-thin High-k Films." Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-97100.
Full textAbstract:
In the thesis CuPc thin films were investigated by (in situ) SE and RAS, which are employed to determine the out-of-plane and in-plane optical anisotropy and molecular orientation, respectively. CuPc is a promising candidate of organic semiconductors used in organic field effect transistors, organic light emitting diodes and organic solar cells. Vicinal Si(111) substrates are interesting due to the in-plane anisotropy caused by the steps and terraces on the surface. The strength of in-plane anisotropy of vicinal Si(111) is dependent on the offcut angle. The influence of offcut angle on out-of-plane and in-plane molecular orientation in CuPc thin films is explored. The in situ investigation of CuPc films suggests that structural changes occur during film growth. In addition, two different surface modification layers were utilized to examine the effect on CuPc molecular orientation: OTS monolayer with upright standing molecules and PTCDA layers with flat lying molecules. Metal-organic interface plays an important role in organic electronic devices. In-CuPc is chosen to be an example system investigated employing in situ SE and RAS. When In was thermally evaporated onto CuPc film, In atoms firstly diffuse into the CuPc film underneath and then aggregate to form clusters on top. Hafnium dioxide (HfO2) is currently a hot topic to replace the conventionally used SiO2 as gate dielectrics in order to minimize leakage current when further scaling down microelectronic devices. Since HfO2 films are often crystalline, in order to obtain amorphous films which are beneficial to minimize leakage current, aluminum oxide (Al2O3) (k value: 9) which stays amorphous at much higher temperatures are combined to overcome this difficulty. Two series of ultra-thin samples were deposited by atomic layer deposition: mixed layers HfxAl1-xOz and bilayers HfO2 on Al2O3. Optical constants and bandgap are determined using SE in the energy range of 0.7-10 eV. It is found that the (effective) optical bandgap of both mixed layer and bilayer structures can be tuned by the film composition. Aging effect of high-k films was observed after storage of samples in air for two months, which is attributed to further oxidation of the dielectric films caused by the oxygen diffusion from ambient air to high-k filmsIn dieser Arbeit werden dünne Schichten aus Kupferphthalozyanin (CuPc) mittels spektroskopischer (in-situ) Ellipsometrie (SE) und (in-situ) Reflektions-Anisotropie-Spektroskopie (RAS) untersucht, um die optische Anisotropie in einer Ebene parallel und senkrecht zur Schichtoberfläche und die molekulare Orientierung zu bestimmen. CuPc ist ein aussichtsreicher Kandidat als organischer Halbleiter in organischen Feldeffekt-Transistoren, organischen Leuchtdioden und organischen Solarzellen. Vizinale Si(111)-Substrate sind wegen der Anisotropie in der Substratebene interessant, die durch die Treppen und Terrassen auf der Oberfläche verursacht wird. Die Stärke der Anisotropie der vizinalen Si(111)-Oberfläche ist vom Schnittwinkel (Offcut) abhängig. Es wird der Einfluss des Offcut-Winkels auf die molekulare Orientierung in dünnen CuPc-Schichten parallel und senkrecht zur Substratoberfläche untersucht. Die in-situ Untersuchungen von CuPc-Schichten weisen darauf hin, dass strukturelle Veränderungen beim Wachstum auftreten. Darüber hinaus wurden zwei unterschiedliche Oberflächenmodifizierungsschichten, um deren Wirkung auf die molekulare Orientierung von CuPc zu untersuchen, verwendet: eine OTS-Monoschicht mit aufrecht stehenden Molekülen und PTCDA-Schichten mit flach liegenden Molekülen. Metall-organische Grenzflächen spielen eine wichtige Rolle in organischen elektronischen Bauelementen. In-CuPc wird als Beispiel für ein Metall-organisches System durch in-situ SE und RAS untersucht. Wenn In thermisch auf eine CuPc-Schicht aufgedampft wird, diffundieren In-Atome zunächst in die darunterliegende CuPc-Schicht und bilden dann Cluster auf der Schicht. Hafniumdioxid (HfO2) ist ein heißer Kandidat für das Ersetzen des herkömmlich als Gate-Dielektrikum verwendeten SiO2 mit dem Ziel, die Leckströme bei der weiteren Verkleinerung mikroelektronischer Bauelemente zu minimieren. Um amorphe Schichten, die vorteilhaft zur Minimierung der Leckströme sind, zu erhalten, werden die HfO2-Schichten, die oft kristallin sind, mit Aluminiumoxid (Al2O3) (k-Wert: 9) kombiniert, das bei wesentlich höheren Temperaturen amorph bleibt. Zwei Serien von ultra-dünnen Proben wurden durch Atomlagenabscheidung hergestellt: Mischschichten HfxAl1-xOz und Doppelschichten HfO2 auf Al2O3. Die optischen Konstanten und Bandlücken wurden mittels SE im Energiebereich von 0,7 bis 10 eV bestimmt. Es hat sich gezeigt, dass die (effektive) Bandlücke der Misch- und Doppelschichten durch die Komposition abgestimmt werden kann. Nach Lagerung der High-k-Schichten für zwei Monate an Luft konnte ein Alterungseffekt beobachtet werden. Dieser wird auf die weitere Oxidation der dielektrischen Schichten, die durch Sauerstoffdiffusion aus der Umgebungsluft in die High-k-Schichten ermöglicht wird, zurückgeführt