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1
Fourie, Christoffel Johannes Stephanus. "In-situ subsurface density estimations using a seismic technique." Thesis, University of Pretoria, 2007. http://hdl.handle.net/2263/23395.
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A new geophysical method was developed to satisfy a need for in-situ density measurements. Various situations, such as a gravity dam wall requires that density measurements should be done without damage to the structure. The sample volume should also not be that large in order to be sensitive enough for variations. This method measures the in-situ density of the weathered layer and other man made structures, using seismic waves in three directions. The seismic waves utilized are P-waves and S-waves. It is however surface waves that are treated like body waves because they do not separate at this shallow depth. These waves are very sensitive to the attenuation factor, which is in turn sensitive to certain physical properties of the propagation medium. This factor is utilsed when the multi layer problem is encountered. The maximum depth of exploration is 2-5m and depends solely on the seismic skin depth. This method utilises a large base plate. The source is a large sledge hammer and shots are done at each side of the base plate. Different dominant frequencies are identified and used to calculate the densities of the layers associated with that specific frequency. The velocities of the subsurface are determined by small seismic refraction surveys. The method will find application mainly in the civil and engineering geology fields. The main application will be to determine subsurface densities and small movement elasticity modulli for engineers to aid in obtaining adequate design parameters. Case studies on three different geologic environments are presented. The results indicate that this method will be useful, although certain modifications are recommended to make this method even faster and more user friendly.Thesis (PhD)--University of Pretoria, 2009.
Geology
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Fourie, Christoffel Johannes Stephanus. "In-situ subsurface density estimations using a seismic technique." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01162009-110629/.
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Quincey, Paul. "Production of Nb3̲Sn superconductors by the in situ technique." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379838.
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Le, Thiez Pierre. "Modélisation numérique de la combustion in situ à co-courant /." Rueil-Malmaison : Paris : Institut français du pétrole ; diffusion Technip, 1986. http://catalogue.bnf.fr/ark:/12148/cb349661609.
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Huang, Wei. "In-situ stress determination in concrete structures by centre hole technique." Thesis, University of Portsmouth, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442572.
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Larroumet, Damien. "Evaluation of the Raman spectroscopy technique for in situ corrosion studies." Thesis, Sheffield Hallam University, 2005. http://shura.shu.ac.uk/19941/.
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Laser Raman spectroscopy has been widely used for corrosion studies but it appeared that, in most of the cases, the sample under investigation was removed from the media in which it has been corroded prior the Raman investigation. The necessity of running 'ex situ' analysis was often due to the poor Raman response due to the absorption of the scattered light by the solution. A large number of studies have previously been conducted after increasing the amount of scattered light by using surface enhanced Raman spectroscopy. Unfortunately, removing the sample from the media in which it has been corroded, or applying metal islands onto the sample under investigation may have a significant effect on the sample's electrochemical reactions. Therefore, the objective of the current work was to evaluate the possibility of using conventional Raman spectroscopy for in situ corrosion studies. The first stage of the research was to identify the potential advantages and the limitations of the technique itself. Once these parameters were identified, it was necessary to assess the technique through different experimental tests. Two model systems, both based on pure iron wires, were exposed to 3.5 % NaCl solution. From both systems, we showed that first a layer of lepidocrocite (gamma-FeOOH) was developing with time at open circuit potential and second that the anodic reaction started with the formation of magnetite which later oxidised to lepidocrocite. Further experiments on iron, performed in three different buffer solutions (borate, carbonate and phosphate) permitted us to observe different oxidation reactions. Although no Raman data could be obtained from the iron sample immersed in borate solution, it was possible firstly to identify the reactions associated to the anodic / cathodic waves visible on the cyclic voltammograms and second to follow the development of the oxide layers and propose a model representation of the passive film. The passive film developed in phosphate buffer solution was identified as a mixture of Fe[3](PO[4])[2.]8H[2]O and FePO[4].xH[2]O. Further pitting experimental tests examined the electrochemical resistance of the passive film developed in such solution. It has therefore been shown through the series of experiments describe here that conventional Raman spectroscopy is an appropriate tool to study, in situ, corrosion processes.
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Allery, Annie. "Amplification du gène ABL par PCR in situ dans des suspensions cellulaires (contribution technique)." Bordeaux 2, 1995. http://www.theses.fr/1995BOR2P080.
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Negim, Osama Le Coustumer Philippe Mench Michel. "New technique for soil reclamation and conservation in situ stabilisation of trace elements in contaminated soils /." S. l. : S. n, 2009. http://ori-oai.u-bordeaux1.fr/pdf/2009/NEGIM_OSAMA_2009.pdf.
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Schilling, Sibylle. "Liquid in situ analytical TEM : technique development and applications to austenitic stainless steel." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/liquid-in-situ-analytical-tem-technique-development-and-applications-to-austenitic-stainless-steel(fd490551-7d7a-4b2e-9b1f-917b5f8165b3).html.
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Environmentally-assisted cracking (EAC) phenomena affect the in-service behaviour of austenitic stainless steels in nuclear power plants. EAC includes such degradation phenomena as Stress Corrosion Cracking (SCC) and Corrosion Fatigue (CF). Factors affecting EAC include the material type, microstructure, environment, and stress. This is an important degradation issue for both current and Gen III+ light water reactors, particularly as nuclear power plant lifetimes are extended ( > 60 years). Thus, it is important to understand the behaviour of the alloys used in light water reactors, and phenomena such as SCC to avoid failures. Although there is no agreement on the mechanism(s) of SCC, the importance of localized electrochemical reactions at the material surface is widely recognised. Considerable research has been performed on SCC and CF crack growth, but the initiation phenomena are not fully understood. In this project, novel in situ analytical TEM techniques have been developed and applied to explore localised reactions in Type 304 austenitic stainless steel. In situ transmission electron microscopy has become an increasingly important and dynamic research area in materials science with the advent of unique microscope platforms and a range of specialized in situ specimen holders. In metals research, the ability to image and perform X-ray energy dispersive spectroscopy (XED) analyses of metals in liquids are particularly important for detailed study of the metal-environment interactions with specific microstructural features. To further facilitate such studies a special hybrid specimen preparation technique involving electropolishing and FIB extraction has been developed in this thesis to enable metal specimens to be examined in the liquid cell TEM specimen holder using both distilled H2O and H2SO4 solutions. Furthermore, a novel electrode configuration has been designed to permit the localized electrochemical measurement of electron-transparent specimens in the TEM. These novel approaches have been benchmarked by extensive ex situ experiments, including both conventional electrochemical measurements and microcell measurements. The results are discussed in terms of validation of in situ test data as well as the role of the electron beam in the experiments. In situ liquid cell TEM experiments have also explored the localized dissolution of MnS inclusions in H2O, and correlated the behaviour with ex situ experiments. Based on the research performed in this thesis, in situ liquid cell and in situ electrochemical cell experiments can be used to study nanoscale reactions pertaining to corrosion and localized dissolution leading to "precursor" events for subsequent EAC phenomena.
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Rugiero, François. "Les neurones sensoriels myentériques : étude in situ par la technique de Patch Clamp." Aix-Marseille 3, 2003. http://www.theses.fr/2003AIX30042.
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Les principaux courants ioniques des neurones myentériques AH in situ ont été étudiés en patch clamp dans le duodenum de cobaye. Ih régule la résistance d'entrée des neurones AH. La conotoxine GVIA, mais pas l'agatoxine IVA, abrège le potentiel d'action et bloque l'AHP qui est donc couplée aux canaux Ca2+ de type N. Nous avons aussi découvert un courant Na+ résistant à la TTX (TTX-R INa). TTX-R INa s'active et s'inactive lentement et possède une composante persistante. La substitution du Cl-intracellulaire par le F- hyperpolarise les paramètres dépendants du voltage de TTX-R INa, lui conférant les propriétés de NaN/NaV1. 9 dans les DRG. Des expériences de RT-PCR, single cell RT-PCR et immunohistochimie indiquent que l'ARNm et la sous-unité NaV1. 9 sont présents dans les neurones AH. Dans les neurones AH, NaN présente aussi une inactivation originale associant une diminution ultra lente ( max=100 s) de NaN à un ralentissement des cinétiques d'activation (m) et d'inactivation (hf)Whole-cell patch-clamp recordings from guinea pig duodenal myenteric neurons were used to study the major currents of AH neurons in situ. Ih contributes to the resting conductance. The conotoxin GVIA, but not the agatoxin IVA, shortens the action potentials and blocks the AHP, which is then coupled to N- type Ca2+ channels. AH neurons express a previously unreported, TTX-resistant Na+ current (TTX-R INa). TTX-R INa activates and inactivates slowly and exhibits a persistent component. Substituting intracellular F- for Cl- shifts the voltage-dependent parameters of TTX-R INa leftward, confering TTX-R INa the properties of NaN/NaV1. 9 in the DRGs. Consistently, RT-PCR, single-cell profiling and immunostaining detect NaV1. 9 mRNA and subunits in AH neurons. In AH neurons, NaN also displays an original inactivation associating an ultra slow ( max=100 s) decline of NaN with a slowing down of both activation (m) and fast inactivation (hf) kinetics
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Cerminara, Giulia. "Optimized management of old municipal solid waste landfill with in-situ aeration technique." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3422354.
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La presente tesi di dottorato è stata focalizzata sulla gestione ottimizzata delle vecchie discariche per rifiuti solidi urbani (RSU). In particolare, si è ipotizzato di applicare la tecnica dell’aerazione in-situ all’interno di una vecchia discarica al fine di ridurre il potenziale impatto a lungo termine e massimizzare la rimozione dei composti del carbonio e dell’azoto. Precedenti studi hanno dimostrato l’efficacia dell’aerazione in-situ intermittente per il miglioramento della stabilità biologica di una discarica di rifiuti solidi urbani.
Considerandone dunque anche i vantaggi economici, l'aerazione in-situ è stata applicata in modalità intermittente e sono stati così valutati due principali aspetti:
1. La fattibilità del processo di denitrificazione in una vecchia discarica RSU caratterizzata da contenuto molto basso di carbonio organico biodegradabile, sfruttando le condizioni anossiche generate dall'aerazione intermittente. In particolare, è stata analizzata la capacità di un vecchio sistema discarica di ricorrere sia alla via eterotrofa che a quella autotrofa per la rimozione dei nitrati, a seconda del substrato disponibile;
2. I possibili effetti dell’aerazione intermittente sul potenziale rilascio dei metalli pesanti in fase liquida ed il loro comportamento nel percolato e nel rifiuto solido, considerando la possibile influenza della tecnica dell’aerazione in-situ sulle condizioni interne del sistema discarica.
Un ulteriore esperimento è stato condotto per valutare un aumento della rimozione della sostanza organica residua in una vecchia discarica RSU, accoppiando l’aerazione in-situ alla tecnologia a celle combustibili microbiche (MFC) al fine di sfruttare i vantaggi di entrambi.
Tutti gli aspetti sono stati analizzati durante numerosi test in scala di laboratorio mediante l’impiego di reattori di simulazione di discarica.
I risultati dell’attività di ricerca possono essere riassunti come segue:
Il processo di denitrificazione non sembra essere inibito all’interno di una vecchia discarica per RSU, in quanto i nitrati possono essere rimossi per via eterotrofa e/o autotrofa a seconda della tipologia di substrato disponibile nel sistema. Sebbene la via eterotrofa possa essere considerata preferenziale, quando la sostanza organica biodegradabile non risulta disponibile o è prossima allo zero, la rimozione dei nitrati può avvenire in modo autotrofo, anche se più lentamente.
I risultati relativi ai test effettuati sui metalli pesanti nel percolato e nel rifiuto solido sembrano confermare il ruolo dominante del meccanismo di adsorbimento all’interno del sistema discarica, che ha ridotto il rilascio di metalli pesanti nel percolato dopo l'aerazione e ha mantenuto piuttosto costante il contenuto di metalli nel rifiuto solido. Conseguentemente, i metalli pesanti non sembrano costituire un fattore di rischio a seguito dell’aerazione in-situ in discarica.
I risultati preliminari relativi l’integrazione della tecnologia MFC con i reattori di simulazione di discarica hanno evidenziato alcuni aspetti critici del sistema, quali la debolezza del materiale catodico, la grande influenza della modalità di ricircolo del percolato sulle prestazioni dell'intero sistema e la scelta ottimale del flusso di aerazione necessario per mantenere aerato il compartimento catodico.
Queste considerazioni evidenziano la necessità di modificare la configurazione MFC all'interno dei reattori di simulazione di discarica.
La presente tesi di dottorato è divisa in due parti principali. Nella prima parte sono sintetizzati l’attività di ricerca svolta ed i principali risultati. La seconda parte descrive in dettaglio tutti gli esperimenti e i relativi risultati, riportando gli articoli scritti durante il corso di dottorato.The Ph.D. research project was focused on the optimized management of old municipal solid waste (MSW) landfills. In particular, it was supposed to apply the in-situ aeration technique within an old landfill in order to reduce the long-term pollution potential and to maximize the removal of nitrogen and carbon compounds. Previous studies proved that intermittent in-situ aeration is an effective tool to improve the biological stability of a MSW landfill. Considering the economic advantages, the in-situ aeration technique was applied in an intermittent way; two main aspects, not still well understood were considered: 1. the occurrence of denitrification process in old MSW landfills characterized by very low biodegradable organic carbon content, taking advantage of the anoxic conditions of the intermittent aeration. In particular, it was analysed the capacity of an old landfill system to exploit both the heterotrophic and autotrophic pathway for nitrogen removal, according to the available substrate; 2. the possible effects of the intermittent aeration on the potential release of heavy metals into the liquid phase and their behaviour both in the leachate and in the solid waste material, considering that the application of in-situ aeration technique may affect the internal conditions of the landfill system. A further lab-scale experiment was carried out to evaluate the increase of the in-situ aeration efficiency to remove the residual organic carbon within an old landfill. The in-situ aeration was coupled with the microbial fuel cells (MFCs) technology in order to exploit the advantages of both of them. All aspects have been evaluated during several lab-scale tests by means of landfill simulating bioreactors. Results of all experiments carried out during the Ph.D. Course can be summarized as follows. Denitrification process does not seem to be limited in a very old MSW landfill as it can occur in a heterotrophic and/or autotrophic way according to the kind of available substrate. Although the heterotrophic pathway can be considered the preferred one, when the biodegradable organic matter is not available or it is close to zero, nitrate can be removed in a autotrophic way, even if more slowly. The results of the experiments on the behaviour of heavy metals in the leachate and in the solid waste matrix seem to confirm the dominant role of adsorption mechanism within the landfill system that reduces the release of heavy metals in the leachate after aeration and keeps quite constant the metals content in the solid waste material. Therefore, heavy metals in landfill leachate do not seem a major concern in case of in-situ aeration. The preliminary results of the integration of MFCs with landfill bioreactors pointed out some critical aspects of the system, such as the weakness of the cathode material, the great influence of the leachate recirculation mode on the performance of the whole system and the optimal choice of the aeration flux required to keep the cathodic compartment aerated. These considerations highlight the need of slightly modify the configuration of the MFC system within the landfill simulation reactors. The present Ph.D. thesis includes the description of the research activities with the related results and it is divided in two main parts. In the first part, named “Thesis development” the Ph.D. research activity and the main results are briefly summarized. The second part, named “List of Papers” describes in details all the experiments and the related results, listing all the papers written during the Ph.D. course.
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Zhang, Hao, Robert Kuschmierz, and Jürgen Czarske. "3D interferometric shape measurement technique using coherent fiber bundles." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A34957.
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In-situ 3-D shape measurements with submicron shape uncertainty of fast rotating objects in a cutting lathe are expected, which can be achieved by simultaneous distance and velocity measurements. Conventional tactile methods, coordinate measurement machines, only support ex-situ measurements. Optical measurement techniques such as triangulation and conoscopic holography offer only the distance, so that the absolute diameter cannot be retrieved directly. In comparison, laser Doppler distance sensors (P-LDD sensor) enable simultaneous and in-situ distance and velocity measurements for monitoring the cutting process in a lathe. In order to achieve shape measurement uncertainties below 1 µm, a P-LDD sensor with a dual camera based scattered light detection has been investigated. Coherent fiber bundles (CFB) are employed to forward the scattered light towards cameras. This enables a compact and passive sensor head in the future. Compared with a photo detector based sensor, the dual camera based sensor allows to decrease the measurement uncertainty by the order of one magnitude. As a result, the total shape uncertainty of absolute 3-D shape measurements can be reduced to about 100 nm.
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Bury, D. R. "The rapid quenching of iron based alloys by an in-situ rapid quenching technique." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356671.
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Dumas, Raphaël. "Analyse biomécanique de la correction des scolioses par la technique du modelage in situ." Paris, ENSAM, 2001. http://www.theses.fr/2002ENAMA018.
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L'objectif de cette étude est l'analyse d'une technique chirurgicale de réduction de la déformation coliotique, au travers des différents outils que sont la reconstruction tridimensionnelle du rachis dans les temps pré et post opératoires et la simulation par la méthode des éléments finis. Un dispositif de stéréoradiographie spécifique a été développé et a permis la reconstruction du rachis d'une vingtaine de patients scoliotiques. Cette modélisation géométrique a été validée en terme d'orientation relative des vertèbres reconstruites et a conduit à une analyse de la déformation du rachis et de sa correction chirurgicale, de manière segmentaire et au coeur même de la "torsion" de la scoliose. Les phénomènes de correction siégeant pendant la chirurgie ont été appréhendés lors de la simulation par éléments finis de deux cas réels, l'un de cyphose et l'autre de scoliose. Cette simulation a été basée sur un modèle global et personnalisé du rachis où le comportement élasto-plastique de l'instrumentation et les conditions aux limites complexes ont été pris en compte (les manoeuvres du chirurgien se traduisant par les charges et décharges successives de flexion surune tige attachée au rachis). Les résultats prédictifs de simulation se sont révélés cohérents, comparés à la reconstruction tridimensionnelle post opératoire. Ces outils d'analyse peuvent constituer une aide au clinicien lors du diagnostic et de la planification de l'opération chirurgicaleThe purpose of this study was to analyse the surgical correction of scolioticdeformity through several biomechanical tools : a pre and post operative three-dirnensionalreconstruction of the spine and a finite element model. A specific device was developed and enabled the three-dimensionai reconstruction of twenty scoliotic patients. The three-dimensional relative orientations of the reconstructed vertebrae were validated. Thisgeometrical modelling allowed to analyse the spinal déformations and the effects of the surgery. This analysis was performed at the segmentai level and at the ± torsionai , level of the scoliotic curves. The correction mechanisms during the surgery were analysed through the simulation of two clinicalcases (one kyphotic and one scoliotic patients). A global personalized model was thus usedincluding the elasto-plastic behaviour of the implants and the complex boundary conditions (severalbendings of a rod correspond to successive load and unload). The prédictive results were foundcoherent compared to the post operative three-dimensionai reconstructions. These means of analysis could yield future clinical tools for diagnosis and surgical planning
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Ramaël, Bruno. "Caractérisation in situ des propriétés mécaniques des parois vasculaires par une technique non invasive." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2314/document.
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La thèse s’axe sur l’identification des propriétés mécaniques des artères faciales. Elle s’inscrit dans le cadre du projet FlowFace, qui porte sur l’étude du réseau artériel facial par Imagerie de Résonance Magnétique (IRM). Elle s’appuie sur une campagne de mesures effectuées sur un échantillon de 30 témoins au CHU d’Amiens, qui a permis d’obtenir de manière non invasive l’évolution de la déformation des vaisseaux, ainsi que la mesure des débits les parcourant. Des pressions diastoliques et systoliques ont été mesurées au niveau du bras, indépendamment des mesures IRM. L’objectif de la thèse a été de modéliser la déformation patient-spécifique des vaisseaux sanguins et de mettre en place une technique d’optimisation, afin de déterminer leurs propriétés mécaniques par analyse inverse. Des simulations du comportement des vaisseaux sanguins ont été réalisées au moyen des logiciels d’ANSYS Inc., en modélisant les interactions fluide-structure aussi bien en couplage fort que faible. L’objectif a été de déterminer les déformations pariétales induites par les conditions hémodynamiques, ainsi que les pertes de charge dans les vaisseaux considérés. Les simulations ont mis en jeu des modèles hyperélastiques grande déformation pour simuler le comportement des parois. Les déplacements prédits par le modèle numérique ont été comparés aux déplacements expérimentaux mesurés par IRM. Les propriétés mécaniques des vaisseaux ont été identifiées au moyen de la technique d’optimisation proposée dans la suite ANSYS et basée sur les algorithmes de gradient et algorithmes génétiques. La méthode d’identification a été validée sur des fantômes de vaisseaux, consistant en des tubes cylindriques en élastomère, et pour lesquelles des mesures de déformation sous écoulement pulsé ont été acquises par imagerie IRM. Les valeurs des propriétés mécaniques ainsi déterminées ont été comparées à celles obtenues par tests de traction et tests de dilatation. Un des points cruciaux de l’identification a consisté en la détermination de l’état non pré-contraint. S’il est un paramètre connu pour les fantômes de vaisseaux, il est à déterminer pour les vaisseaux natifs. Le challenge de cette thèse a aussi été de déterminer les propriétés hyperélastiques des vaisseaux sanguins à partir des valeurs systoliques et diastoliques de pression et déformation. La méthode a permis de conclure que le module tangent en diastole avoisine 200 KPa alors que celui en systole se trouve dans un intervalle entre 300 KPa et 1 MPaThis thesis is based on identifying the mechanical properties of facial arteries. It is part of FlowFace project, which focuses on the study of the facial arterial system by MRI imaging. It is based on a measurement campaign conducted on a sample of 30 people at the Hospital of Amiens, which allowed obtaining noninvasively the evolution of the blood vessel deformation and the measurement of the flow. Diastolic and systolic pressures were measured at the arm independently of the MRI measurements. The aim of the thesis was to model the deformation of blood vessels and to implement an optimization technique to determine their mechanical properties by inverse analysis using MRI measurements of deformation. Simulations of the behavior of the blood vessels were performed, using ANSYS Inc. software, modeling fluid-structure interactions both strong and weak coupling. The objective was to determine the parietal deformations induced by hemodynamic conditions and pressure drops in the vessels concerned. The simulations involved hyperelastic and large deflection models to simulate the behavior of the wall. They allow calculate the numerical displacements that we compared with experimental displacements measured by MRI, the aim is that the difference between numerical and experimental be as low as possible to deduce the adequate mechanical parameters for the artery. To identify the mechanical properties of the vessels, the optimization technique proposed in ANSYS based on genetic algorithms or gradient algorithms was used. The identification method was validated on cylindrical tubes (elastomer), for which deformation measurements were acquired by MRI imaging under pulsating flow. The values of mechanical properties determined were compared with those obtained by traction tests and dilatation tests. One of the crucial points of identification involves the determination of the non-stress state. If it is a known parameter for the elastic tube, it has to be determining for blood vessels. The challenge of this thesis is to determine from a "minimum" quantity of pressure and deformation information, the hyper-elastic properties of blood vessels. The method based on a patient-specific geometry deformation concluded that the tangent modulus in diastole is approximately 200kPa while that in systole is in a range of 300 kPa to 1 MPa
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Amutis, Rikki Lynn 1958. "An unsaturated fractured rock sampling technique by in situ thermoelectric condensation of water vapor." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/191953.
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Water vapor in the airspace of an unsaturated fractured rock may be sampled by reduction of the air temperature of the medium to its dew point and retrieval of the condensed liquid sample. The required temperature Change was generated in this research by a thermoelectric cooling module, which operates according to the Peltier cooling effect. Laboratory studies of this technique involved the development of the module’s heat sink system and calibration of the instrument for cooling temperatures and condensation rates obtained by variations in the applied current. Temperature and vapor density Changes produced in the air space surrounding the instrument when operated in a moist environment were also evaluated. Field studies performed in an unsaturated, fractured, densely-welded tuff have shown the instrument to be capable of vapor collection, although at a rate lower than that established under laboratory conditions. Applications of this technique include evaluation of oxygen and hydrogen isotopes of moisture in unsaturated media and travel time studies of flow through the unsaturated zone using isotopes as tracers.
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Girinsky, Olivier. "Pré-industrialisation d'un procédé de consolidation de sol par bio-calcification in situ." Phd thesis, Université d'Angers, 2009. http://tel.archives-ouvertes.fr/tel-00557098.
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Dans les pays à fort risque sismique, les fondations bâties sur un sous-sol trop meuble peuvent avoir des conséquences désastreuses. En effet, dans certain cas, les mouvements sismiques provoquent des tassements, en particulier lorsque les sous-sols granulaires sont saturés en eau. Ce phénomène dit de liquéfaction ou perte de la résistance des sols, résulte de la montée de la pression interstitielle de l'eau lorsque les vibrations sismiques tendent à tasser les grains les uns contre les autres. Pour éviter l'effondrement des édifices, le génie civil renforce la résistance mécanique des terrains plus ou moins perméables, en procédant à des injections de matériaux par le biais de forages. Afin d'améliorer les procédés de consolidation des sols, une nouvelle technique compte apporter une réponse en utilisant des cristaux de carbonate de calcium précipités in situ par voie microbiologique. La précipitation bactérienne du carbonate de calcium peut s'accomplir par l'hydrolyse de l'urée, via l'enzyme uréase. Ceci conduit à l'alcalinisation du micro environnement, permettant la précipitation d'ions carbonates en présence d'ions calcium. Sporosarcina pasteurii a été choisi car c'est un micro-organisme alcalinophile, non pathogène et détenteur de concentration intracellulaire élevée en uréase. L'objectif était d'utiliser industriellement ce micro-organisme pour son pouvoir calcifiant, afin d'améliorer la cohésion des grains de sol, en milieu saturé, sans en obturer la porosité. Trois axes de recherche menés conjointement, ont été définis pour ce travail de préindustrialisation du procédé de bio consolidation in situ. Le premier axe a été l'obtention d'un milieu de production de biomasse, industriel, permettant de stabiliser l'accession aux fortes activités enzymatiques. Cette étape est indispensable du fait des exigences d'application du procédé sur le chantier, éloignées des conditions physiologiques de la bactérie S. pasteurii. Il a été vital de décoder les modalités et la composition d'un milieu de culture industriel propre à favoriser la production de S. pasteurii et d'uréase. Ce travail a établi les principaux paramètres de suivi de culture et leur signification physiologique. Il a permis d'étudier la régulation de la synthèse de l'enzyme uréase et de proposer un modèle de régulation chez S. pasteurii. Le second aspect de recherche s'est attaché à créer une solution calcifiante à partir d'un mélange d'urée et de sel de calcium. Des colonnes de sable fin ont été utilisées pour évaluer l'impact, sur la bio calcification, de deux sources de sel de calcium, le nitrate et le chlorure de calcium. Les résultats mettent en avant, l'existence d'une réduction de la vitesse d'hydrolyse en présence d'ion calcium et l'absence de différence significative de résistance à la compression (RC) entre les deux sels. D'autre part, lorsque les activités enzymatiques d'hydrolyse sont moindres, le processus de bio calcification, paraît plus stable et efficace. De nombreuses images au microscope électronique à balayage (MEB) ont confirmé ces résultats. Enfin, une amélioration du procédé vient de la proposition d'une solution calcifiante, additionnée de très faibles quantités de matière organique, afin de favoriser l'élongation des cristaux de carbonate de calcium dans les zones inter-granulaires. Le troisième axe a été la mise en place pour une application en chantier, d'un protocole d'injection en colonne de sable fin d'une suspension de biomasse suivie d'une solution calcifiante. Ces travaux ont permis d'identifier, une corrélation entre les zones de dépôt de biomasse et les portions de sable consolidés, ainsi que les principaux facteurs responsables de l'hétérogénéité de la bio calcification. La densité cellulaire et la granulométrie bactérienne définissent par filtration mécanique et physicochimique un premier profil de distribution de la biomasse en milieu poreux. En fonction du niveau d'activité enzymatique et de la qualité de la suspension bactérienne injectée, la solution calcifiante interagit en précipitant sous forme de flocs et en amenant un changement local de viscosité. Pendant l'injection, l'écoulement des fluides redéfinit le premier profil de biomasse par un lessivage au sein du système poreux. La granulométrie du sable et la vitesse d'injection influencent également le lessivage. Grâce à ces travaux, l'hétérogénéité de la bio-calcification a été diminuée en intégrant dans le protocole d'injection, des temps d'arrêt d'injection pour l'immobilisation des fluides.
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Stroich, Christopher Michael. "The development of a novel technique to measure in-situ solubilities in supercritical carbon dioxide." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60503.pdf.
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Abedi, Esfahani Erfan. "Development of an in-situ monitoring technique for hydrogen uptake evaluation from lubricated tribo-contacts." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/19670/.
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The majority of rolling bearings are made from steel due to its suitable mechanical properties. It has been demonstrated that hydrogen evolution from lubricated contacts significantly shortens the steel fatigue life. Significant efforts have been made so far to understand the mechanism of hydrogen-induced failure. However, the failure mechanism is complex and a conclusive theory has remained unknown. The main aim of this study is to develop a novel method, based on the modified Devanathan-Stachurski technique, to experimentally assess hydrogen intrusion into the steel. This new technique enables the study of the hydrogen source in a lubricated contact and the rate of its permeation into the steel. The hydrogen intrusion from various lubricants has been evaluated at both room temperature and high temperature. The effect of water contamination, anti-wear and friction modifier additives in poly-alpha-olefin base oil on tribologically-induced hydrogen uptake were investigated. The results suggest a significant influence of water on hydrogen intrusion. The ZDDP anti-wear and MoDTC friction modifier could reduce hydrogen uptake by forming a uniform tribofilm. On the other hand, the hydrogen permeation is promoted by ZDDP additive when the tribofilm is patchy. This is speculated to be due to the ZDDP decomposition products acting as poisonous agents for recombination of hydrogen atoms. The results indicate that water contamination is more detrimental in presence of ZDDP additive in the lubricant. The study shows that hydrogen is liberated from decomposition of hydrocarbon molecules. The liberation of hydrogen is tied to the rubbing process. The surface rubbing forms a nascent steel surface with active sites by removing contaminants and surface oxide layer. This fresh metal surface catalyses the lubricant decomposition process. It also reveals that hydrogen permeation rate is higher when the load and sliding speed are higher mainly due to the higher wear rate.
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Charonko, Cami Marie. "Evaluation of an In Situ Measurement Technique for Streambank Critical Shear Stress and Soil Erodibility." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/33401.
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The multiangle submerged jet test device (JTD) provides a simple in situ method of measuring streambank critical shear stress (Ï c) and soil erodibility (kd). Previous research showed streambank kd and Ï c can vary by up to four orders of magnitude at a single site; therefore, it is essential to determine if the large range is due to natural variability in soil properties or errors due to the test method. The study objectives were to evaluate the repeatability of the JTD and determine how it compares to traditional flume studies. To evaluate the repeatability, a total of 21 jet tests were conducted on two remolded soils, a clay loam and clay, compacted at uniform moisture content to a bulk density of 1.53 g/cm^3 and 1.46 g/cm^3, respectively. To determine the similarity between JTD and a traditional measurement method, JTD Ï c and kd measurements were compared with measurements determined from flume tests.
The JTD kd and Ï c ranged from 1.68-2.81 cm^3/N-s and 0.28-0.79 Pa, respectively, for the clay loam and 1.36-2.69 cm^3/N-s and 0.30-2.72 Pa, respectively, for the clay. The modest variation of kd and Ï c for the remolded soils suggests the JTD is repeatable, indicating the wide range of parameters measured in the field was a result of natural soil variability. The JTD median kd and Ï c, except clay loam kd (clay loam kd = 2.31 cm^3/N-s, Ï c = 0.45 Pa; clay kd = 2.18 cm^3/N-s, Ï c = 1.10 Pa) were significantly different than the flume values (clay loam kd = 2.43 cm^3/N-s, Ï c = 0.23 Pa; clay kd = 4.59 cm^3/N-s, Ï c = 0.16 Pa); however, considering the range of potential errors in both test methods, the findings indicate the multiangle submerged jet test provides reasonable measurement of erosion parameters in a field setting.
Master of Science
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Li, Yanying. "Understanding of pesticides in waters and soils using a novel in situ dynamic sampling technique." Thesis, Lancaster University, 2018. http://eprints.lancs.ac.uk/125600/.
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There has been increasing concern about the widespread occurrence and persistence of pesticides in the environment. Pesticides can transport among and between environmental compartments, causing pollution in water, soil and air, and posing potential risks to humans and the ecosystem. There is a need to study the fate and behaviour of pesticides in the environment. Over the last few decades passive sampling approaches have aroused attention in detecting pesticides, but they are still under development. In this thesis, the passive sampling technique of diffusive gradients in thin-films (DGT) was developed and validated for pesticides in water and soils for the first time. The DGT technique was developed for in situ measurement of 9 pesticides in water. The compounds were carefully selected to represent a wide range of properties and classes, so that the technique may have wider applicability in future. Two types of binding material (HLB and XAD 18) were used and compared. Laboratory testing was carried out with various controlled experiments. HLB showed higher binding capacity but with slower uptake than XAD 18. The principle of DGT was confirmed as the mass accumulated by DGT was inversely related to the thickness of diffusive layer and proportional to the deployment time. The performance of the DGT sampler was found to be independent of pH (4.7-8.2), dissolved organic matter concentration (< 20 mg L-1) and ionic strength (0.01-0.25M). Several laboratory and field trials were conducted to confirm the usage of DGT for in situ measurement of pesticides in water and soils. DGT has great potential to be applied to trace organic contaminant studies in soils and sediments, but so far work research on this line has been very limited. DGT was therefore investigated for in situ measurement of atrazine (ATR) and its 5 metabolites in soils, and compared with other two approaches to predict bioavailability to maize and to assess the ATR degradation pathway. The results showed that DGT performed best in measuring the bioavailability of total ATR (ATR and its metabolites) to maize. Hydroxylation was the dominant degradation procedure during aging and maize growth in the test soils. This could be well characterized using DGT. DGT was also deployed in a group of aged soils with different pH, soil types and ATR contaminated levels, to explore the behaviour of atrazine in soils and its sorption/desorption. Soil properties had influence on the labile pool size (Kd) and re-supply capability of ATR (R), while aging affected the labile pool in some soils, but had only a slight influence on re-supply. The DIFS (DGT-induced fluxes in soil/ sediment) model was employed to further characterize the kinetics of desorption from the solid phase to the solution phase, this showed that desorption kinetics and the labile pool size commonly affected the re-supply. Owing to the frequently simultaneous occurrence of ATR and arsenic (As) in the environment, DGT equipped with precipitated ferrihydrite binding gel was deployed to investigate the effect of ATR on the availability of As in soils. The addition of ATR did not impact on the measurements of As availability in the test soils, in the concentration range (up to 50 mg kg-1 ) used. This research has demonstrated that DGT is an effective tool for measuring pesticides in soils and waters. It can be used for monitoring purposes, and in experiments designed to better understand pesticide fate, behaviour, availability and to help with assessment of their risk in the environment.
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Chin, Yuan-Tung. "Studies of passivation of iron and its breakdown by chloride ions using in situ spectroscopic ellipsometric technique." Case Western Reserve University School of Graduate Studies / OhioLINK, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=case1054563395.
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Negim, Osama. "New Technique for Soil Reclamation and Conservation: In Situ Stabilization of Trace Elements in Contaminated Soils." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2009. http://tel.archives-ouvertes.fr/tel-00408020.
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L'accumulation de métaux toxiques dans le sol est principalement héritée de matériaux parents ou d'éléments résultant de l'activité humaine. Par conséquent, de nouvelles techniques sont en cours d'élaboration pour remédier à ces contaminations dans les sols pollués, telles que la phytoremédiation et la stabilisation in situ. La stabilisation in situ est une technique commune de réduction des effets négatifs des métaux et métalloïdes, tels que As, Cr, Cu, Cd et Zn dans les sols contaminés par l'ajout d'amendements. L'application de matières alcalines telles que les laitiers d'aciéries et un laitier modifié enrichie en phosphates dans le sol constitue un outil prometteur pour la réduction de la mobilité et la biodisponibilité des éléments traces dans les sols contaminés ainsi que pour l'assainissement du sol et l'amélioration de ses propriétés physique, chimique et minéralogique, ainsi que la production végétale.
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Böhm, Jochen. "In situ tensile testing at the limits of X-ray diffraction a new synchrotron-based technique." Stuttgart Max-Planck-Inst. für Metallforschung, 2004. http://deposit.d-nb.de/cgi-bin/dokserv?idn=972182810.
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Touitou, Jamal. "Development of an in-situ spatially resolved technique to investigate catalysts in a plug flow reactor." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.677844.
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This thesis presents, in detail, all the steps of the development of a new in-situ spatially resolved method to probe gas phase concentrations and temperature with minimum invasiveness. From the literature review, it was noted that no techniques developed to date were designed to investigate packed powdered catalyst beds which simultaneously obtain the gas concentrations and the temperature profile. Within this thesis, details of the development of a prototype and further optimisation of a spatial resolution technique for packed powdered catalyst beds were disclosed. The technique was designed to have negligible impact on the packed powdered catalyst bed with the use of the smallest equipment available. Significantly, a number of validation tests of the spatially resolved technique were conducted and the results proved that the technique was working under different experimental conditions. The results of these validation tests highlighted the improvements of the optimised spatial resolution system, which provided twice as many sampling points as the prototype, as well as the additional benefit of simultaneous temperature recording. Additionally, the invasiveness of the spatially resolved technique was investigated using Computational Fluid Dynamics (CFD); more precisely the sampling capillary was found to have negligible impact on the packed catalyst bed during the experiment. Furthermore, the results obtained experimentally have been compared with simulations using a micro kinetic model. The results obtained showed that a hybrid model (simulated concentrations and experimental temperature) allowed a more accurate picture of the phenomena occurring in the packed catalyst bed which was one of the initial aims of the development of the spatially resolved technique.
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Negim, Osama. "New technique for soil reclamation and conservation : in situ stabilisation of trace elements in contaminated soils." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13821/document.
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Les sols sous contraintes que ce soit du point de vue charges polluantes comme avec les Métaux Traces (MT) ou bien du point de vue stress hydrique (perte des capacités de rétention menant à la désertification des sols) concernent de nombreux espaces du territoire national, de même que la région du pourtour Méditerranéen. Le nombre de sites pollués par des substances inorganiques affectant de larges espaces est en constante augmentation. Les stratégies pour leur rémédiation sont variées mais très peu envisagent la dépollution tout en restaurant les propriétés pédologiques des sols concernés. La rémédiation comme la restauration des capacités fertilisantes de sols pollués sont un enjeu international. Pour cela, la stratégie de cette étude porte sur le développement d’outils technologiques innovants basée sur la phytorémédiation assistée par des matrices duales de sols contaminés par des MT (Cuivre, Chrome, Arsenic). Ces matrices duales ont une action double concomitante en permettant une immobilisation ou un piégeage des MT tout en favorisant la repousse végétale ou la catalyse de la croissance végétale. Le piégeage peut se faire par l’apport d’amendement ayant des capacités d’échanges (généralement liées à l’existence de phase allophane et/ou d’un réseau poral important) et de rétention (liées au réseau porale et à l’existence de phases minérales type phosphates, silice amorphe, oxydes hydroxydes de fer-manganèse). L’élaboration, à partir de laitiers d’aciéries, d’une matrice susceptible d’adsorber des MT (aspect dépollution) tout en favorisant la pousse végétale (aspect amendement) nous a permis de tester ce produit de synthèse. La seconde originalité de cette étude est d’analyser le potentiel de ces matrices, non seulement à différentes échelles (du pot en passant par le stade mésocosme et jusqu’au champ), du point de vue impact écotoxique – dépollution de sols associé à une re-végétalisation. Cette dernière participe également au transfert des charges polluantes (MT) depuis l’amendement de synthèse ou du sol vers, et dans le réseau racinaire des radicelles et ainsi favoriser la réhabilitation des propriétés hydriques des sols par le développement d’un couvert végétale pérenne. On conjugue ainsi un apport dépolluant à celui de maintient de la potentielle anti-désertification grâce au développement de solutions innovantes respectueuses de l’environnement sur la base de technologie douce valorisant les co produits de l’industrieSoil contamination by trace elements is a widespread problem in many parts of the world. The accumulation of toxic metals in soil is mainly inherited from parent materials or inputs through human activities. In fact, one of the sources of soil contaminations is very important resulting from chemical widely used wood preservative industries in aquatic environments and storing the wood after treatment by chromated copper arsenate (CCA). Elements such as As, Cu, Cr, and Zn can be found in excess in contaminated soils at wood treatment facilities, especially when Cu sulphates and chromated copper arsenate (CCA) were used as a preservative against insects and fungi, which may result in soil phytotoxicity as well as toxic to plants, animals and humans. New techniques are being developed to remediate trace elements in contaminated soils such as phytoremediation and in situ stabilization. In situ stabilization technique or in situ immobilisation is one of the common practices for reducing negative effects of metals and metalloids such as As, Cr, Cu, Pb, Cd and Zn in contaminated soils by adding amendments. Alkaline materials are usually added to acidic soils to improve soil chemical and physical properties and also to reduce the mobility and bioavailability of contaminant. Slag, which consists of calcium oxide, phosphorus oxide, silicon oxide, iron oxide, and other metal oxides, is an alkaline by-product of metallurgical processes or a residue of incineration processes. Slags have been successfully used to soil reclamation and soil fertiliser. It has been used as a soil additive to reduce various metals contaminated soil by precipitation and adsorption on the surface of metal oxide. The objectives of this Ph.D study were to evaluate the physical, chemical soil properties and the distribution of trace elements in contaminated soil. Also to evaluate the characteristics of two different slags samples, a basic slag (BS) and a basic slag phosphate (BSP) which are alkaline by-products of the French steel industry and which used as a soil amendments to improve soil properties and for the in situ immobilisation of copper and metals in chromated copper arsenate (CCA) contaminated soil
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Wu, Yi Sun. "Fabrication of in-situ MgB₂ thin films on Al₂O₃ substrate using off-axis PLD technique." Access electronically, 2007. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080917.103857/index.html.
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Schirru, Michele. "Development of an ultrasonic sensing technique to measure lubricant viscosity in engine journal bearing in-situ." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/12980/.
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This work presents a novel technique to measure viscosity in-situ and in real time in engine component interfaces by means of an ultrasonic technique. Viscosity is a key parameter in the characterization of lubrication regime in engine parts because it can be related to friction in the contact, and to the lubricant film thickness. Ultrasound is a non-destructive and non-invasive technique that is based on the reflection of sound from interfaces. The reflection from a solid-air boundary can identify, for instance, the presence of a crack in a material, while reflection from a solid-liquid interface can help detecting the properties of the liquid sample. Reflection of longitudinal waves measures fluid film thickness and chemical composition, while the reflection of ultrasonic shear waves measures the fluid viscosity. The viscosity measurements based on ultrasonic reflection from solid-fluid boundaries are referred to as reflectance viscometry techniques. Common ultrasonic reflectance viscometry methods can only measure the viscosity of Newtonian fluids. This work introduces a novel model to correlate the ultrasonic shear reflection coefficient with the viscosity of non-Newtonian oils by means of the Maxwell model analogy. This algorithm overcomes the limitation of previous models because it is suitable for the analysis of common engine oils, and because it relies only on measurable parameters. However, viscosity measurements are prohibitive at the metal-oil interfaces in auto engines because when the materials in contact have very different acoustic impedances the sound energy is almost totally reflected, and there is very little interaction between the ultrasonic wave and the lubricant. This phenomenon is called acoustic mismatch. When acoustic mismatch occurs, any valuable information about the liquid properties is buried in measurement noise. To prove this, the common reflectance set-up was tested to measure the viscosity of different lubricants (varying from light base oils to greases) using aluminium as solid boundary. More than 99.5% of the ultrasonic energy was reflected for the different oils, and accurate viscosity measurement was not possible because the sensitivity of the ultrasonic measurement at the current state of the art is of ±0.5%. Consequently, the discrimination by viscosity of the oil tested was not possible. In this study a new approach is developed. The sensitivity of the ultrasonic reflectance method is enhanced with a quarter wavelength matching layer material. This material is interleaved between metal and lubricant to increment the ultrasonic measurement sensitivity. This layer is chosen to have thickness and mechanical properties that induce the ultrasonic wave to resonate at the solid-liquid interface, at specific frequencies. In this work, resonance is associated with the destructive interaction between the wave that is incident to the matching layer and the wave that is reflected at the matching layer-oil interface. This solution brings a massive increment in the ultrasonic measurement sensitivity. The matching layer technique was first tested by enhancing the sensitivity of the aluminium-oil set-up that was affected by acoustical mismatch. A thin polyimide layer was used as a matching layer between aluminium and the engine oil. This probe was used as ultrasonic viscometer to validate the sensing technique by comparison with a conventional viscometer and by applying a temperature and pressure variation to the samples analysed. The results showed that the ultrasonic viscometer is as precise as a conventional viscometer when Newtonian oils are tested, while for Non-Newtonian oils the measurement is frequency dependent. In particular, it was noticed that at high ultrasonic frequency only the viscosity of the base of the oil was measured. The ultrasonic viscometer was used to validate the mathematical model based on the Maxwell analogy for the correlation of the ultrasonic response with the liquid viscosity. At a second stage, this technique was implemented in a journal bearing. The ultrasonic viscometer was mounted in the shaft to obtain the first viscosity measurement along the circumference of a journal bearing at different rotational speeds and loads. The ultrasonic viscometer identified the different viscosity regions that are present in the journal bearing: the inlet, the regions characterized by the rise in temperature at the contact and the maximum loaded region were the minimum film thickness occurs. The results were compared with the analytical isoviscous solution of the Reynolds equation to confirm that the shape of the angular position-viscosity curves was correct. Finally, the method was preliminarily tested on a coated shell bearing to show that the coating presents in bearing, like iron-oxide or babbit, is a good matching layer for the newly developed ultrasonic viscometer technique. This means that ultrasonic transducers, with sizes as small as a pencil tip, have the potential to be mounted as viscometers in real steel bearings where the coating layer in contact with the fluid acts as a matching layer. Overall, the results obtained showed that this technique provides robust and precise viscosity measurements for in-situ applications in engine bearings.
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Lifton, Nathaniel Aaron 1963. "A new extraction technique and production rate estimate for in situ cosmogenic carbon-14 in quartz." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/289000.
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The potential utility of in situ cosmogenic ¹⁴C (in situ ¹⁴C) in surficial process studies is widely recognized, yet a reliable means of isolating it has proved difficult to develop. Here we present a new method for isolating in situ ¹⁴C in quartz that yields more precise estimates of production rates than achieved by previously published extraction techniques. The new technique involves resistance heating of samples, and collection of all evolved carbon as CO₂ between 500°C and 1500°C. Our improved technique holds three distinct advantages over other extraction methods: (1) we can identify and quantitatively eliminate atmospheric/organic ¹⁴C contamination, (2) we can identify the in situ ¹⁴C component unambiguously without assumptions of ¹⁴CO/¹⁴CO₂ production proportions within the rock or equilibria on extraction, and (3) background ¹⁴C levels are consistently low. To develop our new procedures, we identified and sampled wave-cut quartzite benches associated with Lake Bonneville's two highest shorelines, as well as basalts that erupted into the late Pleistocene lake at Tabernacle Hill. Comparison of ¹⁴C thermal release patterns from the shoreline quartzites to well-shielded quartzite samples showed that contaminant ¹⁴C is released at ≤ 500°C, and that ¹⁴C released from 500 to 1500°C is essentially all in situ-produced. Two replicate analyses yield a sampling site production rate of 59.8 ± 4.6 (¹⁴C atoms/g SiO₂)/yr. Uncertainties in altitude and latitude scaling factors yield a 2σ range of sea-level, >60° geomagnetic latitude ¹⁴C production rate estimates consistent with an independent estimate based on an experimental ¹⁴C/¹⁰Be production ratio (Reedy et al., 1994) and ¹⁰Be production rate estimates from similar Lake Bonneville shoreline sites (Gosse and Klein, 1996). Our preferred production rate estimate is thus 18.2 ± 2.0 (¹⁴C atoms/g SiO₂)/yr. This estimate is also consistent with revised in situ ¹⁴C production rate estimates based on our previously published data, but is lower and more precise--indicating that we have successfully reduced contaminant ¹⁴C and other sources of variability in our data. After we have replicated these Lake Bonneville results, our new extraction procedures should bring in situ ¹⁴C into the mainstream of process-oriented cosmogenic nuclide surface studies.
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Morris, Bryan George Oneal. "In situ monitoring of reactive ion etching." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31688.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: May, Gary; Committee Member: Brand,Oliver; Committee Member: Hasler,Paul; Committee Member: Kohl,Paul; Committee Member: Shamma,Jeff. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Wang, Xuzhu. "Beam-folding ultraviolet-visible Fourier transform spectrometry and underwater cytometry for in situ measurement of marine phytoplankton." HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/814.
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Greene, John A. "An Investigation of Engineered Injection and Extraction as an in situ Remediation Technique for Uranium-Contaminated Groundwater." Thesis, University of Colorado at Boulder, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10682286.
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During in situ remediation of contaminated groundwater, a treatment chemical is injected into the contaminated groundwater to degrade a contaminant through chemical reaction that occurs in the subsurface. Reactions and subsequent contaminant degradation occur only where the treatment chemical contacts the contaminant long enough to complete degradation reactions. Traditional in situ groundwater remediation relies on background groundwater flow to spread an injected treatment chemical into a plume of contaminated groundwater.
Engineered Injection and Extraction (EIE), in which time-varying induced flow fields are used to actively spread the treatment chemical into the contaminant plume, has been developed to increase contact between the contaminant and treatment chemical, thereby enhancing contaminant degradation. EIE has been investigated for contaminants degrading through irreversible, bimolecular reaction with a treatment chemical, but has not been investigated for a contaminant governed by complex biogeochemical processes. Uranium fate and transport in subsurface environments is governed by adsorption, oxidation reduction, solution, and solid-phase interactions with naturally occurring solution species, microbial communities, minerals and aquifer media. Uranium primarily occurs in aqueous, mobile U(VI) complexes in the environment but can be reduced to sparingly soluble, immobile U(IV) solid-phase complexes by native dissimilatory metal reducing bacteria.
This work investigates the ability of EIE to promote subsurface delivery of an acetate-amended treatment solution throughout a plume of uranium-contaminated groundwater to promote in situ growth of native microbial communities to immobilize uranium. Simulations in this investigation are conducted using a semi-synthetic flow and reactive transport model based on physical and biogeochemical conditions from two uranium contaminated sites: the Naturita Uranium Mill Tailings Remedial Action (UMTRA) Project site in southwestern Colorado and the Old Rifle UMTRA Project site in western Colorado.
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Ahmed, Sadia. "Investigation of in-situ nanoimprinting of cell surface receptors: potential of a novel technique in biomarker research." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/98406.
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Biomarkers are biological characteristics that can be observed or measured during disease conditions, and compared to the healthy state. Biomarkers have been used in medical history to study disease progression, to develop drugs, or to predict drug efficacy. However, in complex diseases such as in cancer, biomarkers vary tremendously among patients and disease stages. Cell surface receptors, proteins that are located at the cell surface and deliver external signals into the cell, are a significant group of easily-detectable biomarkers. Along with the detection of particular biomarkers related to a disease, extensive characterization of expression patterns is necessary to optimize their application. Therefore, we designed a technique to imprint or capture the expression pattern of these receptors on silver nanoparticles. We incorporated branched molecules that can simultaneously bind to the target receptors and the nanoparticle surface. To develop the technique, we used melanocortin receptor 1 (MC1R), a receptor present at high levels on the surface of melanoma cells, as a test system. We determined optimum binding of this molecule in an established melanoma cell line, WM-266-4. We also synthesized a labeled molecule that was used to estimate the number of MC1R proteins on these cells. These studies indicate that this might be a promising approach for developing sensitive and cost-effective tools to characterize cell surface receptors in studying complex diseases and cell mechanisms.MS
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Avet-Loiseau, Hervé. "Hybridation in situ en fluorescence : validation de la technique dans les hémopathies malignes : application au myélome multiple." Nantes, 1998. http://www.theses.fr/1998NANT11VS.
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Serege, Matthieu. "Développement d'une nouvelle technique d'analyse pour les nanosctructures gravées par plasmas : (S)TEM EDX quasi in-situ." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT097/document.
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Avec la diminution perpétuelle des dimensions des circuits intégrés, la gravure de dispositifs à l’échelle nanométrique constitue un véritable défi pour les procédés plasma qui montrent des limites dans le cas d’empilement de couches minces notamment. L’anisotropie de gravure réside sur la formation de couches de passivations sur les flancs des motifs, qui agissent comme film protecteur bloquant la gravure latérale par les radicaux du plasma. Cependant, cette fine couche est responsable de l’apparition de pente dans les profils gravés et il est difficile de contrôler son épaisseur. De plus, une deuxième couche réactive est aussi formée en fond de motifs. Les produits de gravures sont formés au sein de cette couche permettant d’augmenter la vitesse de gravure du substrat. Il a récemment été admis que contrôler l’épaisseur de ces couches réactives constitue le paramètre clé pour obtenir une gravure à très haute sélectivité.Cependant, les couches réactives à analyser hautement réactives, en raison de leur forte concentration en halogènes, s’oxydent immédiatement lors de la remise à l’air.Cette étude se propose de développer une approche originale, simple et extrêmement puissante pour observer ces couches de passivation quasi in-situ (sans contact avec l’air ambiant) : Apres gravure, l’échantillon est transporté sous vide à l’intérieur d’une valise spécifique jusqu’à une enceinte de dépôt, où il est alors encapsulé par une couche métallique (PVD assisté par magnétron). L’échantillon ainsi encapsulé peut être observé ex-situ sans modification chimique grâce à des analyses STEM EDXAs the size of integrated circuit continues to shrink, plasma processes are more and more challenged and show limitations to etch nanometer size features in complex stacks of thin layers. The achievement of anisotropic etching relies on the formation of passivation layers on the sidewalls of the etched features, which act like a protective film that prevents lateral etching by the plasma radicals. However, this layer also generate a slope in the etch profile and it’s difficult to control its thickness. Another thin layer called “reactive layer” is also formed at the bottom of the features. Etch products are formed in this layer allowing a high etch rate of the substrate. It starts to be realized that controlling the thickness of this reactive layer is the key to achieve very high selective processes.However, the layers to be analyzed are chemically highly reactive because they contain large concentrations of halogens and they get immediately modified (oxidized) when exposed to ambient atmosphere.In this work we develop an original, simple and extremely powerful approach to observe passivation layers quasi in-situ (i.e. without air exposure): After plasma etching, the wafer is transported under vacuum inside an adapted suitcase to a deposition chamber where it is encapsulated by a metallic layer (magnetron sputtering PVD). Then, the encapsulated features can be observed ex situ without chemical / thickness modification thanks to (S)TEM-EDX analysis
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Defrance-Bouvard, Véronique. "Apport de la technique d'hybridation in situ avec des sondes biotinylées dans la recherche de l'infection par les papillomavirus humains." Lyon 1, 1987. http://www.theses.fr/1987LYO11732.
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Choi, Changhoon. "Kinetic study of copper chemistry in chemical mechanical polishing (CMP) by an in-situ real time measurement technique." [Ames, Iowa : Iowa State University], 2008.
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Jospin, Maëlle. "Caractérisation électrophysiologique in situ à l'aide de la technique de Patch-Clamp de la cellule musculaire striée du Nématode Caenorhabditis Elegans." Lyon 1, 2004. http://tel.archives-ouvertes.fr/docs/00/06/37/69/PDF/JospinM.pdf.
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Caenorhabditis elegans est un modèle animal de choix pour l'identification à partir d'animaux mutants des gènes intervenant dans différents comportements. En revanche, la caractérisation des mutants à l'échelle cellulaire a longtemps été limitée par la taille restreinte de l'animal. La mise au point de la dissection et l'application de la technique de patch-clamp et d'imagerie Ca2+ sur la cellule musculaire striée de C. Elegans nous ont permis de caractériser pour la première fois les principales conductances ioniques de cette cellule. Nous avons montré le rôle crucial que jouaient les canaux Ca2+ EGL-19 dans le couplage excitation-contraction et mis en évidence les propriétés d'activation de canaux K+ voltage-dépendants et Ca2+-activés. Nous avons aussi démontré que le canal Na+ UNC-105, de la famille des dégénérines, n'était pas mécanosensible comme le supposaient les études génétiques, tandis qu'un autre membre de cette famille s'est avéré sensible à l'acidification extracellulaireCaenorhabditis elegans is a powerful model system widely used to investigate the relationships between genes and behaviours. However, physiological studies at the cellular level have been greatly restricted by the small size of the animal. Using in situ patch-clamp and Ca2+ imaging techniques on body-wall muscle cells, we have characterised the main ionic conductances of these cells. We gave evidence for the crucial role of EGL-19 voltage-dependent Ca2+ channels in excitation-contraction coupling and described the activation properties of voltage-dependent and Ca2+-activated K+ channels. We also demonstrated that the UNC-105 Na+ channel of the degenerin family was not mechanically-gated contrary to the genetic-based model, while another member of this channel family was found to be activated by external protons
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Karadas, Ozge. "Collagen Scaffolds With In Situ Grown Calcium Phosphate For Osteogenic Differentiation Of Wharton." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612975/index.pdf.
Full textAbstract:
COLLAGEN IN SITU GROWN CALCIUM PHOSPHATE SCAFFOLDS
FOR OSTEOGENIC DIFFERENTIATION OF WHARTON&rsquoS JELLY AND MENSTRUAL BLOOD STEM CELLS Karadas, Ö
zge M.Sc., Department of Biotechnology Supervisor : Prof. Dr. Vasif Hasirci Co-Supervisor: Assoc. Prof. Dr. Gamze Torun Kö
se February 2011, 91 pages The importance of developing new techniques for the treatment of bone and joint diseases is increasing continuosly together with the increase of human population and the average life span. Especially bone fractures as a result of osteoporosis are often seen in humans older than 50 years old. The expenses of bone and joint disease operations are very high and the duration of recovery is long. Because of these reasons World Health Organization, The United Nations and 37 countries announced that the years 2000-2010 is the Bone and Joint Decade. Tissue engineering is an alternative approach to clinically applied methods. In this study collagen scaffolds crosslinked with genipin, to improve the stability of foams in culture media, were prepared by lyophilization. To mimic the natural bone structure calcium phosphate mineral phase in the foam was formed by wet chemical precipitation. Collagen concentration (0.75% and 1%, w/v), freezing temperature (-20 oC and -80 oC) of the collagen solution before lyophilization and immersion duration (2x4 h and 2x48 h) of the foams in calcium and phosphate solutions for wet chemical precipitation were changed as process v parameters of foam production. Pore size distribution and porosity analysis as well as compression test were performed for characterization of the scaffolds. The foam with 1% w/v collagen concentration, frozen at -20 oC before lyophilization and immersed for 2x4 h in calcium and phosphate solution was chosen for in vitro cell culture studies. The defined foam had 70% porosity and pore sizes varying between 50 and 200 &mu
m. The elastic modulus and compressive strength of the foam was calculated as 127.1 kPa and 234.5 kPa, respectively. Stem cells isolated from Wharton&rsquo
s jelly (WJ) and menstrual blood (MB) were seeded to foams to compare their osteogenic differentiation. Both cells are isolated from discarded tissues and used in this study as an alternative to the commonly used cells which are isolated by invasive techniques such as bone marrow stem cells. Cells were seeded to collagen foams with and without calcium phosphate (CaP). It was observed that WJ cells proliferated during 21 days on collagen foams without CaP, but MB cell number decreased after day 14. Collagen foams with CaP supported the alkaline phosphate (ALP) activity compared to tissue culture polystyrene (TCPS) and foams without CaP. Contrarily lower cell numbers achieved on CaP containing collagen foams, possibly because of the calcium and phosphate concentration changes in the medium and as the result of osteogenic differentiation. ALP activity of both cell types increased almost 10 times and specific ALP activity (activity per cell) increased 40 times and 150 times for WJ and MB cells, respectively on the CaP containing foams compared to TCPS. Therefore, in this study it was shown that in situ CaP formed collagen foams induce osteogenic differentiation of WJ and MB cells, and these cells isolated from discarded tissues can be used as alternative cell sources in bone tissue engineering applications.
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Brown, Glen, and n/a. "Towards an in situ technique for investigating the role nutrients play in epilithon growth in an Australian upland stream." University of Canberra. School of Resource, Environmental & Heritage Sciences, 2001. http://erl.canberra.edu.au./public/adt-AUC20060614.171246.
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There is limited knowledge and understanding of the role of nutrients and effect of
herbivore grazing on epilithon production in Australian upland rivers. Before
investigating these processes, a method was required that will allow the study of factors
(physical, chemical and biological) that affect epilithon abundance and distribution in
lotic systems. The Thredbo River, Kosciusko National Park, New South Wales,
provided an opportunity to conduct this investigation because it: is relatively
undisturbed; has been intensely studied; is easily accessed; and is of appropriate width
and depth to conduct in-stream experiments.
The specific goals of this research were the: (1) validation of the nutrient-diffusing
substrate method for investigating epilithon responses to nutrients; (2) development of
experimental channels in which to investigate nutrient/epilithon dynamics in an upland
stream; (3) development of a method to inhibit macroinvertebrate grazing from in situ
experimental channels, so that epilithon responses to nutrients with and without grazing
pressure can be studied; and (4) assessment of the ecological implications of nutrient/
epilithon/macroinvertebrate interactions assessed from in-stream experiments.
Major achievements of my research, that advance the study of stream ecology, are as
follows:
· The investigation of the features of nutrient release from terracotta nutrientdiffusing
substrates showed that phosphorus does not readily diffuse through
terracotta clay, probably because terracotta contains known binding agents for
phosphorus, such as iron, and because pores are easily blocked. I concluded that
this type of substrate is inappropriate for studying nutrient dynamics and epilithon
responses to the nutrient(s) limiting growth. The outcomes of this research has
implications for future research using nutrient-diffusing substrates, and of how
nutrient limitation information is interpreted from past research using terracotta
nutrient-diffusing substrates.
· I designed and tested in-stream experimental channels that were functional and
provided near natural conditions for studying the interactions between nutrients/
epilithon/macroinvertebrates, without affecting physical variables not tested for.
The in situ method developed was successful in simulating 'real world'
complexities. Clay paving bricks were used as standardized common surface for
community development because their colour, size and surface texture are similar
to those of natural stones.
· I developed a technique for successfully inhibiting macroinvertebrate grazing from
designated areas, using electricity, without affecting flow and light. This technique
will enable in-stream herbivory studies to assess the effects of macroinvertebrate
grazing pressure on epilithon under natural conditions, including variability in
flow, temperature, light and nutrients. It will allow the vexed question of whether
epilithon biomass is controlled by bottom-up or top-down processes to be
objectively addressed.
The construction of in situ experimental channels that simulate natural conditions,
combined with the non-intrusive methods of macroinvertebrate exclusion and nutrient
addition, resulted in a study design that will facilitate the investigation of biotic
responses to nutrients in Australian upland streams. Using the method developed, I
showed that variable flows in the upper Thredbo River appear high enough to slough
epilithon, but not high enough to dislodge macroinvertebrates. This may mean that in
systems such as the Thredbo River that experience frequent low level disturbance, the
epilithon is unable to reach equilibrium. There is strong top-down control of epilithon
in this stream, with nutrients, temperature and light playing a secondary role. I
concluded that natural variability may be more important than previously considered
and perhaps this, rather than constancy, should be studied.
This thesis adds support to the continuance of multiple factor investigations, and
advocates that such studies be conducted under natural conditions so that the results
are more relevant to natural systems than from studies conducted in controlled
laboratory and outdoor artificial streams. Clearly, the in-stream channels, developed as
part of the current research, will allow research that contributes to our understanding of
community responses to the physical, chemical and biological processes operating in
lotic environments.
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Gilchriest, Travis R. "In situ marking of Culex tarsalis larvae (Diptera: Culicidae) with ¹⁵N a novel technique in mosquito mark-capture studies /." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594501141&sid=4&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Jospin, Maëlle Allard Bruno. "Caractérisation électrophysiologique in situ à l'aide de la technique de Patch-Clamp de la cellule musculaire striée du Nématode Caenorhabditis Elegans." [s.l.] : [s.n.], 2004. http://tel.archives-ouvertes.fr/docs/00/06/37/69/PDF/JospinM.pdf.
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Sena, Filho Marcondes 1984. "Atividade gelatinolítica in situ e imuno-expressão das metaloproteinases 2 e 9 em lesões potencialmente malignas e carcinomas espinocelulares bucais." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289252.
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Orientador: Jacks Jorge JúniorDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-20T03:09:29Z (GMT). No. of bitstreams: 1 SenaFilho_Marcondes_M.pdf: 9539347 bytes, checksum: ecd31e3eb890ecb3fcf26cc3dc064e25 (MD5) Previous issue date: 2012
Resumo: Sabe-se que a transição da mucosa normal para um carcinoma invasivo é um processo complexo, de múltiplas etapas e com etiologia multifatorial, onde as Lesões Potencialmente Malignas (LPMs) são de extrema importância. As LPMs são caracterizadas por uma maior possibilidade de malignização, quando comparadas à mucosa normal. Dentre estas, a Leucoplasia Bucal (LB) é a principal representante. Alguns estudos sugerem que há aumento da atividade de metaloproteinases (MMPs) 2 e 9 em mucosas com displasia epitelial e carcinomas espinocelulares (CECs) bucais, porém isso ainda não está totalmente claro e necessita de mais estudos. Os objetivos deste trabalho foram: 1) Avaliar a expressão imunoistoquímica das metaloproteinases 2 e 9; 2) Mensurar a atividade gelatinolítica total in situ; 3) Avaliar a integridade da lâmina basal através da expressão de colágeno IV; 4) Correlacionar e co-localizar a atividade gelatinolítica total in situ com a imunofluorescência de dupla marcação para colágeno IV e metaloproteinases 2 ou 9; 5) Correlacionar os achados anteriores com os aspectos clínicos e anatomopatológicos;. Foram realizadas 50 coletas (45 lesões e 5 controles) de biópsias oriundas de pacientes com suspeita clínica de lesões potencialmente malignas ou carcinomas bucais. Deste total, 30 (60%) receberam diagnóstico clínico de LB e 15 (30%) de CEC. Histopatologicamente, observou-se que 12 amostras tratavam-se apenas de hiperqueratose e acantose, 08 de displasia epitelial leve/moderada, 08 de displasia epitelial intensa, 10 CEC bem diferenciados e 04 carcinomas pouco diferenciados. Nas analises imunoistoquímicas, observou-se que a MMP-2 é fortemente expressa nos epitélios livres de displasia, diminuindo de acordo com a progressão da displasia epitelial ou indiferenciação da lesão. Ambas as MMPs foram expressas no estroma das lesões com displasia epitelial intensa e CEC's, porém a MMP-9 foi mais acentuada, principalmente nos CEC's indiferenciados. A atividade gelatinolítica in situ foi maior no epitélio dos controles e das hiperqueratoses e acantoses, se co-localizando apenas com a MMP-2. Todos os CEC's e 63% das displasias epiteliais intensas apresentaram descontinuidade da lâmina basal, onde houve co-localização das MMPs com atividade gelatinolítica. Nestas mesmas lesões, houve regiões de co-localização das MMP's, atividade gelatinolítica em lâminas basais ainda íntegras. A baixa expressão gelatinolítica das lesões displásicas e CEC's, correlacionado com as rupturas de lâmina basal e aumento da expressão das MMP's no estroma, além da co-localização das mesmas nas regiões de descontinuidade da lâmina basal, sugerem que as MMP's expressas no estroma das lesões provavelmente estão mais relacionadas com a progressão do tumor do que as expressas pelo parênquima
Abstract: The transition from normal oral mucosa to invasive carcinoma has a complex and multifactorial etiology. Oral leukoplakia (OL) is regarded as the most prevalent potentially malignant oral lesion, with a higher tendency for malignant transformation if compared to normal oral mucosa. Although an increased activity of matrix metalloproteinases (MMPs) 2 and 9 in oral mucosa presenting varying degrees of epithelial dysplasia and oral squamous cell carcinomas (OSCCs) has been suggested, but further investigation is necessary for confirming such association. Therefore, the aim of this research is to evaluate the immunohistochemical expression and the total in situ gelatinolytic activity of MMP-2 and MMP-9 in OL and OSCC, as well as to evaluate the integrity of the basal lamina through the expression of collagen IV, correlating the results obtained with clinical and pathological features. Immunohistochemical, immunofluorescent and in situ zymography reactions were carried out in 5 normal oral epithelium, 12 cases presenting hyperkeratosis and acanthosis with no epithelial dysplasia, 8 mild/moderate epithelial dysplasia, 8 severe epithelial dysplasia, 10 well differentiated and 4 poorly differentiated OSCC's. It was found that MMP-2 expression was higher in oral epithelium devoid of dysplasia, if compared to dysplastic and neoplastic oral epitheliums. In addition, despite both MMPs were expressed in the stroma of severe epithelial dysplasia and OSCC's samples, MMP-9 expression revealed to be more pronounced, especially in poorly differentiated OSCCs. in situ gelatinolytic activity was higher in normal epithelium and those presenting only hyperkeratosis and acanthosis, co-localizing only with MMP-2. All cases of OSCC and 63% of lesions with severe epithelial dysplasia showed discontinuity of the basal lamina, revealing co-localization of MMPs with in situ gelatinolytic activity in regions with continuous and discontinuous basal lamina. Taken together, the results obtained revealed that a low gelatinolytic activity in the parenchyma of dysplastic lesions and OSCC correlated with disruption of the basal lamina and with an increased expression of MMPs in the stroma, suggesting that MMP's expressed in the stroma of the lesions would be more related with tumor progression than MMP's expressed in the lesional parenchyma
Mestrado
Estomatologia
Mestre em Estomatopatologia
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Li-Pook-Than, Andrew. "In Situ Raman Spectroscopy of the Type Selective Etching of Carbon Nanotubes and Their Growth from C60 Seeds." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33014.
Full textAbstract:
In situ Raman spectroscopy was used to explore etching of carbon nanotubes as well as their growth from C60. The thesis is in three parts: (1) C60 seed particles were partially oxidized in air and were used to grow carbon nanotubes and other nanocarbon structures. Seed oxidization was characterized by monitoring the evolution of the Raman Ag(2) peak and the D band, and oxidation temperature was found to be critical to nanotube growth. (2) To further explore oxidation, carbon nanotubes were thermally oxidized in air at different temperatures, while the evolution of different Raman bands was tracked. Etching dynamics and band intensity evolution were tracked in situ. Notably, metallic species were found to etch much more rapidly than semiconducting species of similar diameter. (3) To confirm and expand on this, a novel, simultaneous two-laser Raman spectroscopy setup was used to track the thermal oxidation of carbon nanotubes in O2 and CO2 gases at different temperatures. Metallic species were resonant with one laser line, while semiconducting species were resonant with the other, so changes to sample metallicity could be tracked unambiguously in two separate spectra. Again, metals were found to etch more rapidly. In situ Raman spectroscopy can track the evolution of nanotubes in real time and provide insight into processing. In general, detailed process monitoring like this can help in the development of selective synthesis and processing.
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Guilbault, Evelyne. "Enrichissement des cellules foetales présentes dans le sang maternel et optimisation de la technique d'hybridation in situ détectée en fluorescence." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0021/MQ48930.pdf.
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Michel, Anna Pauline Miranda. "Laboratory evaluation of laser-induced breakdown spectroscopy (LIBS) as a new in situ chemical sensing technique for the deep ocean." Cambridge, Mass. : Woods Hole, Mass. : Massachusetts Institute of Technology ; Woods Hole Oceanographic Institution, 2007. http://hdl.handle.net/1912/1957.
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Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007.Title from Web page (viewed on Mar. 24, 2008). "September 2007." Includes bibliographical references.
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Michel, Anna Pauline Miranda 1976. "Laboratory evaluation of laser-induced breakdown spectroscopy (LIBS) as a new in situ chemical sensing technique for the deep ocean." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42296.
Full textAbstract:
Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2007.Includes bibliographical references.
Present-day expeditionary oceanography is beginning to shift from a focus on short-term ship and submersible deployments to an ocean observatory mode where long-term temporally-focused studies are feasible. As a result, a critical need for in situ chemical sensors is evolving. New sensors take a significant amount of time to develop; thus, the evaluation of techniques in the laboratory for use in the ocean environment is becoming increasingly important. Laser-induced breakdown spectroscopy (LIBS) possesses many of the characteristics required for such in situ chemical sensing, and is a promising technique for field measurements in extreme environments. Although many LIBS researchers have focused their work on liquid jets or surfaces, little attention has been paid to bulk liquid analysis, and especially to the effect of oceanic pressures on LIBS signals. In this work, laboratory experiments validate the LIBS technique in a simulated deep ocean environment to pressures up to 2.76 x 10⁷ Pa. A key focus of this work is the validation that select elements important for understanding hydrothermal vent fluid chemistry (Na, Ca, Mn, Mg, K, and Li) are detectable using LIBS. A data processing scheme that accurately deals with the extreme nature of laser-induced plasma formation was developed that allows for statistically accurate comparisons of spectra. The use of both single and double pulse LIBS for high pressure bulk aqueous solutions is explored and the system parameters needed for the detection of the key analytes are optimized. Using both single and double pulse LIBS, the limits of detection were found to be higher than expected as a result of the spectrometer used in this experimentation. However, the results of this validation show that LIBS possesses the characteristics to be a viable chemical sensing method for in situ analyte detection in high pressure environments like the deep ocean.
by Anna Pauline Miranda Michel.
Ph.D.
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Durrieu, Françoise. "Détection des ARN messagers par cytométrie en flux : mise au point de la technique de marquage amorcé in situ (PRINS)." Bordeaux 2, 1993. http://www.theses.fr/1993BOR23099.
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Esteve, David. "Développement d'une technique de caractérisation optique appliquée au suivi in situ de la croissance d'oxydes fonctionnels par ablation laser pulsé." Paris 11, 2010. http://www.theses.fr/2010PA112385.
Full textAbstract:
Une instrumentation optique entièrement statique permettant le suivi in situ de la croissance d'oxydes fonctionnels par ablation laser pulsé, est présenté. Au travers de l'étude de deux système modèles, que sont la croissance de films minces de La₀. ₆₇Sr₀. ₃₃LMnO₃ sur des pseudo-substrats de SrTiO₃/Si et de couches minces de SrRuO₃ déposées sur des substrats de SrTiO₃ vicinaux, le dispositif proposé permet d'obtenir une précision de mesure sur les épaisseurs de l'ordre de la maille atomique (4Å), d'extraire les paramètres physiques de diffusion des espèces en surface (énergie d'activation de diffusion), mais aussi d'observer et d'identifier les modes de croissance. Ces résultats sont en parfait accord avec la simulation numérique développée, reposant sur des modèles de traitement de réflectivité de systèmes multi couches combiné avec la théorie des milieux effectifsA fully static set up allowing in situ observation of the growth of functionnal oxides grown by pulsed laser deposition, is presented. Through the study of two model systems, those are the growth of thin films of La₀. ₆₇Sr₀. ₃₃LMnO₃ on pseudo-substrate of SrTiO₃/Si and thin layers of SrRuO₃ grown on vicinal substrate of SrTiO₃, the proposed instrumentation permit to achieve a precision about one unit cell (4Å) on thickness measurments, to extract physical parameters of the diffusion of species on the surface (activation energy of diffusion), but also observing and identifying growth modes. These results are in good agreement with the numerical simulation developped, based on the treatment of the reflectivity of multi-layers systems combined with effective medium theory
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Rosie, Kathryn A. "A method for in situ SEM fracture studies of brittle materials using the double torsion technique : application to nuclear graphite." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11099.
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This work concerned the design and development of a miniature double torsion (DT) testing rig, for use inside the chamber of a scanning electron microscope, to perform in situ loading studies of brittle materials using the DT fracture mechanics specimen. The in situ performance of the system inside the SEM was highly satisfactory, while still providing free rotation of the attached stepper motor. Crack growth rates of down to 19nm/s were directly observed in PMMA specimens. It was concluded that the technique displayed merit in its ability to contribute to the knowledge base of slow cracking and damage development in brittle materials, with the advantage being that the gearing ratios of the current device resulted in slower specimen loading rates, which were more controlled, than reported previously.