L’utilisation de semi-conducteurs organiques dans les dispositifs électroniques offre d’intéressantes perspectives. En effet, ils permettent d’alléger le poids de ces dispositifs en plus de diminuer grandement le coût de leur fabrication. Cependant, une des principales problématiques associées à ces semi-conducteurs organiques est leur procédé de fabrication qui requiert des solvants organiques toxiques et de multiples étapes de synthèse. Dans ce travail, un nouveau procédé de synthèse respectueux de l’environnement a été mis au point. Une seule étape était nécessaire à la préparation des semi-conducteurs, en utilisant la réaction de polycondensation entre une diamine et un dialdéhyde. Cette réaction a été réalisée à température ambiante, dans un solvant vert, l’éthanol, et sans utilisation de catalyseurs, minimisant ainsi la consommation énergétique et utilisant un milieu réactionnel de source renouvelable et peu toxique. Après leur dopage, ces polymères ont présentés des propriétés de conduction comparables à celles des principaux semi-conducteurs organiques. La deuxième partie de cette thèse a été consacrée à l’étude de l’utilisation du papier comme support pour les dispositifs d’électronique organique; s’affranchissant ainsi de l’utilisation de substrats généralement non biodégradables et/ou de sources non renouvelables (plastique ou verre). Deux stratégies ont été utilisées à cette fin. La première consistait en un dépôt direct des polymères semi-conducteurs à la surface de filaments de cellulose. La deuxième est basée sur la création d’un lien covalent entre les semi-conducteurs et la pâte Kraft, en utilisant la réaction de cycloaddition 1,3-dipolaire de Huisgen catalysée par le cuivre (CuAAc). / The use of organic semiconductors in electronic devices offers interesting prospects. Indeed, they make it possible to lighten the weight of these devices in addition to greatly reducing the cost of their manufacture. However, one of the main problems associated with these organic semiconductors is their manufacturing process, which requires toxic organic solvents and multiple synthesis steps. In this work, a new environmentally friendly synthesis process has been developed. A single step was necessary for the preparation of the semiconductors, using the polycondensation reaction between a diamine and a dialdehyde.This reaction was carried out at room temperature in ethanol, a green solvent and without the use of catalysts, thus minimizing energy consumption and using a reaction medium from a renewable and low-toxicity source. After their doping, these polymers exhibited conduction properties comparable to those observed for conventional organic semiconductors.The second part of this thesis was devoted to the study of the use of paper as a support for organic electronics devices; hus avoiding the use of generally non-biodegradable and/or non-renewable substrates (plastic or glass). Two strategies have been used to this end. The first consisted of a direct deposit of the semiconducting polymers to the surface of cellulose filaments.The second is based on the creation of a covalent bond between the semiconductors and the Kraft pulp, using the copper-catalyzed Huisgen 1,3-dipolar cycloaddition reaction (CuAAc).

Magnetic fields are fundamental to the structure and dynamics of the Sun’s corona. Observations show them to be locally complex, with highly sheared and twisted fields visible in solar filaments/prominences. The free magnetic energy contained in such fields is the primary source of energy for coronal mass ejections, which are important—but still poorly understood drivers of space weather in the near-Earth environment. In this thesis, a new model is developed for the evolution of the large-scale magnetic field in the global solar corona. The model is based on observations of the radial magnetic field on the solar photosphere (visible surface). New active regions emerge, and their transport and dispersal by surface motions are simulated accurately with a surface flux transport model. The 3D coronal magnetic field is evolved in response to these photospheric motions using a magneto-frictional technique. The resulting sequence of nonlinear force-free equilibria traces the build-up of magnetic helicity and free energy over many months. The global model is applied to study two phenomena: filaments and coronal mass ejections. The magnetic field directions in a large sample of observed filaments are compared with a 6-month simulation. Depending on the twist of newly-emerging active regions, the correct chirality is simulated for up to 96% of filaments tested. On the basis of these simulations, an explanation for the observed hemispheric pattern of filament chirality is put forward, including why exceptions occur for filaments in certain locations. Twisted magnetic flux ropes develop in the simulations, often losing equilibrium and lifting off, removing helicity. The physical basis for such losses of equilibrium is demonstrated through 2D analytical models. In the 3D global simulations, the twist of emerging regions is a key parameter controlling the number of lift-offs, which may explain around a third of observed coronal mass ejections.

No description available.

Ce mémoire contient deux parties consacrées à deux applications des chaînes de particules magnétiques.<br />Le premier chapitre décrit la conception d'un capteur de forces intercolloïdales. Nous présentons différentes expériences permettant de caractériser les particules utilisées. Nous décrivons ensuite la réalisation du montage expérimental et le traitement des données. Enfin, nous comparons cette technique aux autres techniques.<br />Le second chapitre décrit la conception et la réalisation de nageurs à l'échelle microscopique. Nous fabriquons des filaments magnétiques flexibles en alignant des particules sous l'effet d'un champ magnétique. Les particules adjacentes sont reliées par des agents pontants. Nous avons étudié le comportement de ces filaments sous champ. Sous l'effet d'un champ magnétique oscillant, le filament se déforme : une onde se propage alors le long du filament, ce qui engendre une force propulsive, dont nous démontrons l'effet sur un nageur spermatomorphe. Enfin, nous vérifions des prédictions théoriques antérieures.

Actin is one of the most abundant and highly conserved proteins in eukaryotic cells. The globular protein assembles into long filaments, which form a variety of different networks within the cytoskeleton. The dynamic reorganization of these networks - which is pivotal for cell motility, cell adhesion, and cell division - is based on cycles of polymerization (assembly) and depolymerization (disassembly) of actin filaments. Actin binds ATP and within the filament, actin-bound ATP is hydrolyzed into ADP on a time scale of a few minutes. As ADP-actin dissociates faster from the filament ends than ATP-actin, the filament becomes less stable as it grows older. Recent single filament experiments, where abrupt dynamical changes during filament depolymerization have been observed, suggest the opposite behavior, however, namely that the actin filaments become increasingly stable with time. Several mechanisms for this stabilization have been proposed, ranging from structural transitions of the whole filament to surface attachment of the filament ends. The key issue of this thesis is to elucidate the unexpected interruptions of depolymerization by a combination of experimental and theoretical studies. In new depolymerization experiments on single filaments, we confirm that filaments cease to shrink in an abrupt manner and determine the time from the initiation of depolymerization until the occurrence of the first interruption. This duration differs from filament to filament and represents a stochastic variable. We consider various hypothetical mechanisms that may cause the observed interruptions. These mechanisms cannot be distinguished directly, but they give rise to distinct distributions of the time until the first interruption, which we compute by modeling the underlying stochastic processes. A comparison with the measured distribution reveals that the sudden truncation of the shrinkage process neither arises from blocking of the ends nor from a collective transition of the whole filament. Instead, we predict a local transition process occurring at random sites within the filament. The combination of additional experimental findings and our theoretical approach confirms the notion of a local transition mechanism and identifies the transition as the photo-induced formation of an actin dimer within the filaments. Unlabeled actin filaments do not exhibit pauses, which implies that, in vivo, older filaments become destabilized by ATP hydrolysis. This destabilization can be identified with an acceleration of the depolymerization prior to the interruption. In the final part of this thesis, we theoretically analyze this acceleration to infer the mechanism of ATP hydrolysis. We show that the rate of ATP hydrolysis is constant within the filament, corresponding to a random as opposed to a vectorial hydrolysis mechanism. / Aktin ist eines der am häufigsten vorkommenden und am stärksten konservierten Proteine in eukaryotischen Zellen. Dieses globuläre Protein bildet lange Filamente, die zu einer großen Vielfalt von Netzwerken innerhalb des Zellskeletts führen. Die dynamische Reorganisation dieser Netzwerke, die entscheidend für Zellbewegung, Zelladhäsion, und Zellteilung ist, basiert auf der Polymerisation (dem Aufbau) und der Depolymerisation (dem Abbau) von Aktinfilamenten. Aktin bindet ATP, welches innerhalb des Filaments auf einer Zeitskala von einigen Minuten in ADP hydrolysiert wird. Da ADP-Aktin schneller vom Filamentende dissoziiert als ATP-Aktin, sollte ein Filament mit der Zeit instabiler werden. Neuere Experimente, in denen abrupte dynamische Änderungen während der Filamentdepolymerisation beobachtet wurden, deuten jedoch auf ein gegenteiliges Verhalten hin: Die Aktinfilamente werden mit der Zeit zunehmend stabiler. Mehrere Mechanismen für diese Stabilisierung wurden bereits vorgeschlagen, von strukturellen Übergängen des gesamten Filaments bis zu Wechselwirkungen der Filamentenden mit dem experimentellen Aufbau. Das zentrale Thema der vorliegenden Dissertation ist die Aufklärung der unerwarteten Unterbrechungen der Depolymerisation. Dies geschieht durch eine Kombination von experimentellen und theoretischen Untersuchungen. Mit Hilfe neuer Depolymerisationexperimente mit einzelnen Filamenten bestätigen wir zunächst, dass die Filamente plötzlich aufhören zu schrumpfen und bestimmen die Zeit, die von der Einleitung der Depolymerisation bis zum Auftreten der ersten Unterbrechung vergeht. Diese Zeit unterscheidet sich von Filament zu Filament und stellt eine stochastische Größe dar. Wir untersuchen daraufhin verschiedene hypothetische Mechanismen, welche die beobachteten Unterbrechungen verursachen könnten. Die Mechanismen können experimentell nicht direkt unterschieden werden, haben jedoch verschiedene Verteilungen für die Zeit bis zur ersten Unterbrechung zur Folge. Wir berechnen die jeweiligen Verteilungen, indem wir die zugrundeliegenden stochastischen Prozesse modellieren. Ein Vergleich mit der gemessenen Verteilung zeigt, dass der plötzliche Abbruch des Depolymerisationsprozesses weder auf eine Blockade der Enden, noch auf einen kollektiven strukturellen Übergang des gesamten Filaments zurückzuführen ist. An Stelle dessen postulieren wir einen lokalen Übergangsprozess, der an zufälligen Stellen innerhalb des Filaments auftritt. Die Kombination von weiteren experimentellen Ergebnissen und unserem theoretischen Ansatz bestätigt die Vorstellung eines lokalen Übergangsmechanismus und identifiziert den Übergang als die photo-induzierte Bildung eines Aktindimers innerhalb des Filaments. Nicht fluoreszenzmarkierte Aktinfilamente zeigen keine Unterbrechungen, woraus folgt, dass ältere Filamente in vivo durch die ATP-Hydrolyse destabilisiert werden. Die Destabilisierung zeigt sich durch die Beschleunigung der Depolymerisation vor der Unterbrechung. Im letzten Teil der vorliegenden Arbeit untersuchen wir diese Beschleunigung mit theoretischen Methoden, um auf den Mechanismus der ATP-Hydrolyse zu schließen. Wir zeigen, dass die Hydrolyserate von ATP innerhalb des Filaments konstant ist, was dem sogenannten zufälligen Hydrolysemechanismus entspricht und im Gegensatz zum sogenannten vektoriellen Mechanismus steht.

In the presence of a solid-liquid or liquid-air interface, bacteria can choose between a planktonic and a sessile lifestyle. Depending on environmental conditions, cells swimming in close proximity to the interface can irreversibly attach to the surface and grow into three-dimensional aggregates where the majority of cells is sessile and embedded in an extracellular polymer matrix (biofilm). We used microfluidic tools and time lapse microscopy to perform experiments with the polarly flagellated soil bacterium Pseudomonas putida (P. putida), a bacterial species that is able to form biofilms. We analyzed individual trajectories of swimming cells, both in the bulk fluid and in close proximity to a glass-liquid interface. Additionally, surface related growth during the early phase of biofilm formation was investigated. In the bulk fluid, P.putida shows a typical bacterial swimming pattern of alternating periods of persistent displacement along a line (runs) and fast reorientation events (turns) and cells swim with an average speed around 24 micrometer per second. We found that the distribution of turning angles is bimodal with a dominating peak around 180 degrees. In approximately six out of ten turning events, the cell reverses its swimming direction. In addition, our analysis revealed that upon a reversal, the cell systematically changes its swimming speed by a factor of two on average. Based on the experimentally observed values of mean runtime and rotational diffusion, we presented a model to describe the spreading of a population of cells by a run-reverse random walker with alternating speeds. We successfully recover the mean square displacement and, by an extended version of the model, also the negative dip in the directional autocorrelation function as observed in the experiments. The analytical solution of the model demonstrates that alternating speeds enhance a cells ability to explore its environment as compared to a bacterium moving at a constant intermediate speed. As compared to the bulk fluid, for cells swimming near a solid boundary we observed an increase in swimming speed at distances below d= 5 micrometer and an increase in average angular velocity at distances below d= 4 micrometer. While the average speed was maximal with an increase around 15% at a distance of d= 3 micrometer, the angular velocity was highest in closest proximity to the boundary at d=1 micrometer with an increase around 90% as compared to the bulk fluid. To investigate the swimming behavior in a confinement between two solid boundaries, we developed an experimental setup to acquire three-dimensional trajectories using a piezo driven objective mount coupled to a high speed camera. Results on speed and angular velocity were consistent with motility statistics in the presence of a single boundary. Additionally, an analysis of the probability density revealed that a majority of cells accumulated near the upper and lower boundaries of the microchannel. The increase in angular velocity is consistent with previous studies, where bacteria near a solid boundary were shown to swim on circular trajectories, an effect which can be attributed to a wall induced torque. The increase in speed at a distance of several times the size of the cell body, however, cannot be explained by existing theories which either consider the drag increase on cell body and flagellum near a boundary (resistive force theory) or model the swimming microorganism by a multipole expansion to account for the flow field interaction between cell and boundary. An accumulation of swimming bacteria near solid boundaries has been observed in similar experiments. Our results confirm that collisions with the surface play an important role and hydrodynamic interactions alone cannot explain the steady-state accumulation of cells near the channel walls. Furthermore, we monitored the number growth of cells in the microchannel under medium rich conditions. We observed that, after a lag time, initially isolated cells at the surface started to grow by division into colonies of increasing size, while coexisting with a comparable smaller number of swimming cells. After 5:50 hours, we observed a sudden jump in the number of swimming cells, which was accompanied by a breakup of bigger clusters on the surface. After approximately 30 minutes where planktonic cells dominated in the microchannel, individual swimming cells reattached to the surface. We interpret this process as an emigration and recolonization event. A number of complementary experiments were performed to investigate the influence of collective effects or a depletion of the growth medium on the transition. Similar to earlier observations on another bacterium from the same family we found that the release of cells to the swimming phase is most likely the result of an individual adaption process, where syntheses of proteins for flagellar motility are upregulated after a number of division cycles at the surface. / Bakterien sind einzellige Mikroorganismen, die sich in flüssigem Medium mit Hilfe von rotierenden Flagellen, länglichen Fasern aus Proteinen, schwimmend fortbewegen. In Gegenwart einer Grenzfläche und unter günstigen Umweltbedingungen siedeln sich Bakterien an der Oberfläche an und gehen in eine sesshafte Wachstumsphase über. Die Wachstumsphase an der Oberfläche ist gekennzeichnet durch das Absondern von klebrigen, nährstoffreichen extrazellulären Substanzen, welche die Verbindung der Bakterien untereinander und mit der Oberfläche verstärken. Die entstehenden Aggregate aus extrazellulärer Matrix und Bakterien werden als Biofilm bezeichnet. In der vorliegenden Arbeit untersuchten wir ein Bodenbakterium, Pseudomonas putida (P. putida), welches in wässriger Umgebung an festen Oberflächen Biofilme ausbildet. Wir benutzten photolithographisch hergestellte Mikrokanäle und Hochgeschwindigkeits-Videomikroskopie um die Bewegung schwimmender Zellen in verschiedenen Abständen zu einer Glasoberfläche aufzunehmen. Zusätzlich wurden Daten über das parallel stattfindende Wachstum der sesshaften Zellen an der Oberfläche aufgezeichnet. Die Analyse von Trajektorien frei schwimmender Zellen zeigte, dass sich Liniensegmente, entlang derer sich die Zellen in eine konstante Richtung bewegen, mit scharfen Kehrtwendungen mit einem Winkel von 180 Grad abwechseln. Dabei änderte sich die Schwimmgeschwindigket von einem zum nächsten Segment im Mittel um einen Faktor von 2. Unsere experimentellen Daten waren die Grundlage für ein mathematisches Modell zur Beschreibung der Zellbewegung mit alternierender Geschwindigkeit. Die analytische Lösung des Modells zeigt elegant, dass eine Population von Bakterien, welche zwischen zwei Geschwindigkeiten wechseln, signifikant schneller expandiert als eine Referenzpopulation mit Bakterien konstanter Schwimmgeschwindkeit. Im Vergleich zu frei schwimmenden Bakterien beobachteten wir in der Nähe der Oberfläche eine um 15% erhöhte Schwimmgeschwindigkeit der Zellen und eine um 90 % erhöhte Winkel-geschwindigkeit. Außerdem wurde eine signifikant höhere Zelldichte in der Nähe der Grenzfläche gemessen. Während sich der Anstieg in der Winkelgeschwindigkeit durch ein Drehmoment erklären lässt, welches in Oberflächennähe auf den rotierenden Zellkörper und die rotierenden Flagellen wirkt, kann die Beschleunigung und Akkumulation der Zellen bei dem beobachteten Abstand nicht durch existierende Theorien erklärt werden. Unsere Ergebnisse lassen vermuten, dass neben hydrodynamischen Effekten auch Kollisionen mit der Oberfläche eine wichtige Rolle spielen und sich die Rotationsgeschwindigkeit der Flagellenmotoren in der Nähe einer festen Oberfläche grundsätzlich verändert. Unsere Experimente zum Zellwachstum an Oberflächen zeigten, dass sich etwa sechs Stunden nach Beginn des Experiments größere Kolonien an der Kanaloberfläche auflösen und Zellen für ca. 30 Minuten zurück in die schwimmende Phase wechseln. Ergebnisse von mehreren Vergleichsexperimenten deuten darauf hin, dass dieser Übergang nach einer festen Anzahl von Zellteilungen an der Oberfläche erfolgt und nicht durch den Verbrauch des Wachstumsmediums bedingt wird.

Orientadores: André Leon Sampaio Gradvohl, Vitor Rafael Coluci / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-21T23:26:09Z (GMT). No. of bitstreams: 1 Andrijauskas_Fabio_M.pdf: 2796809 bytes, checksum: 9fd4e03f6038d482ed05a64517bb1780 (MD5) Previous issue date: 2013 / Resumo: A quantidade de imagens astronômicas geradas cresce diariamente, além da quantidade já obtida e armazenada. Uma grande fonte de dados são imagens solares, cujo estudo pode detectar eventos que têm a capacidade de afetar as telecomunicações, transmissão de energia elétrica e outros sistemas na Terra. Para que tais eventos sejam detectados, torna-se necessário analisar essas imagens de forma eficiente, levando em conta os aspectos de armazenamento, processamento e visualização. Agregar algoritmos de processamento de imagem e técnicas de computação de alto desempenho facilita o tratamento da informação de forma correta e em tempo reduzido. As técnicas de computação para alto desempenho utilizadas neste trabalho foram desenvolvidas para sistemas híbridos, isto é, aqueles que utilizam uma combinação de sistemas de memórias compartilhada e distribuída. Foram produzidas versões paralelas para sistemas híbridos de técnicas já estabelecidas. Além disso, novas técnicas foram propostas e testadas para esse sistema tais como o Filamento Diffusion Detection. Para avaliar a melhora no desempenho, foram feitas comparações entre as versões seriais e paralelas. Esse texto também apresenta um sistema com capacidade para armazenar, processar e visualizar as imagens solares. Em uma das técnicas de detecção de filamentos, o processo foi acelerado 120 vezes e um processo auxiliar para a detecção de áreas mais brilhantes foi 155 vezes mais rápido do que a versão serial / Abstract: The number of astronomical images produced grows daily, in addition to the amount already stored. Great sources of data are solar images, whose study can detect events which have the capacity to affect the telecommunications, electricity transmission and other systems on Earth. For such events being detected, it becomes necessary to treat these images in a coherent way, considering aspects of storage, processing and image visualization. Combining image processing algorithms and high performance computing techniques facilitates the handling of information accurately and in a reduced time. The techniques for high performance computing used in this work were developed for hybrid systems, which employ a combination of shared and distributed memory systems. Parallel version of some established techniques were produced for hybrid systems. Moreover, new techniques have been proposed and tested for this system. To evaluate the improvement in performance, comparisons were made between serial and parallel versions. In addition to the analysis, this text also presents a system with capacity to store, process and visualize solar images. In one of the techniques for detecting filaments, the process was accelerated 120 times. Also an auxiliary process for the detection of brighter areas was 155 times faster than the serial version / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia

Des systèmes d'absorption Lorentziens, qui sondent les nuages de gaz HI de plus hautes densités de colonne, servent ici à sonder les environnements de galaxies hôtes de noyaux actifs à grand décalage spectral (z > 2). Ceci permet d'étudier l'effet des mécanismes de rétroaction des noyaux actifs sur les galaxies hôtes, tel que les vents à haute vitesse et l'ionisation intense. J'implémente deux techniques pour identifier les systèmes Lorentziens au décalage spectral du quasar dans les données du Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey.Un tel système Lorentzien fait office de coronographe naturel puisqu'il absorbe complètement le rayonnement provenant du noyau actif. Parfois une raie Lyα étroite émise par la galaxie est superposée à l'absorption. J'étudie un échantillon statistiquement complet et je caractérise l'émission. Les systèmes Lorentziens qui révèlent les raies étroites d'émission Lyα les plus lumineuses proviennent de nuages denses et compacts dans la galaxie hôte. Les autres sont dus à des galaxies voisines du quasars.Une deuxième technique consiste à observer des paires de quasars ayant une petite séparation angulaire pour sonder les environnements des galaxies hôtes à des distances transverses inférieures à 90 kpc. J'analyse les propriétés du gaz pour des paires où un système Lorentzien apparait dans le spectre du quasar d'arrière plan coïncident avec le pic d'émission Lyα du quasar de premier plan.Dans une des paires, je détecte une sur-densité de systèmes absorbants à z = 2.69 dans une région correspondant à 6.4 Mpc en distance propre. Les propriétés de cette région suggèrent un filament du milieu intergalactique. / Damped Lyman-α absorbers (DLAs), the highest column density HI Lyman-α (Lyα) absorptions, are used in this thesis to study the environments of high-redshift (z > 2) quasar host galaxies. This is essential for determining how feedback mechanisms from active galactic nuclei (AGN), including high-velocity winds and intense ionizing radiation, impact the host galaxies. Thanks to the large number of quasar sight-lines from the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey, I implement two techniques to identify DLAs that occur at the quasar redshift.Along the sight-line, these DLAs act as natural coronagraphs and completely absorb the broad Lyα emission from the central AGN. In some cases, a narrow Lyα emission line from the quasar host galaxy is superimposed on the DLA trough. I compare coronagraph DLAs that reveal narrow Lyα emission with those that do not in a statistically complete sample and characterize the emission. DLAs with the most luminous narrow Lyα emission peaks may arise from dense, compact clouds in the host galaxy, while the others may be due to neighboring galaxies. With a second technique, I use pairs of quasars with small angular separations to investigate host galaxy environments at distances of less than 90 kpc in the transverse direction. I analyze the gas properties for pairs where a DLA appears in the background quasar spectrum coincident with the foreground quasar Lyα emission peak.In one of the pairs, I also detect an overdensity of Lyman-limit system absorbers at z = 2.69 in a region spanning 2000 km/s (6.4 Mpc proper distance) along the two sight-lines. The overdense region properties suggest an intergalactic medium filament.

The heterogeneity of salivary gland neoplasms have made classification and prognostication of these tumours sometimes difficult, and the in­troduction of techniques, such as enzyme and carbohydrate histochemis­try and electron microscopy have only to a certain extent increased our knowledge in these respects. In the present study immunohistochemical methods have been used to identify intermediate filament proteins (IFP) in normal fetal and adult parotid glands, as well as in salivary neo­plasms. The intermediate filaments (IF) make up the cytoskeleton in eucaryotic cells. Epithelial tissue contains IF composed of different cytokeratins (CK 1-19) whilst mesenchymal tissue generally contains IF composed of vimentin, and the IFP pattern is very stable even during cell transformation. It would thus be possible to further clarify the histogenesis of salivary neoplasms by identifying IFP, in addition the IFP pattern would probably be useful in tumour typing. Furthermore, ultrastructural cytochemical studies, microspectorphotometry on nuclear DNA as well as enzyme secretory studies of certain tumour types were carried out, in order to further characterize the biology of salivary neoplasms. The immunohistochemical investigations showed that in normal parotid tissue, the different cell types differed in IFP expression: acinar cells express mainly CK 18 and myoepithelial cells mainly CK 17 and 19, whilst duct cells contained a broad range of CK. Vimentin could in ad­dition to CK be detected in myoepithelial cells and basal cells of ex­cretory ducts. Fetal parotid cells showed a similar CK pattern as mature duct cells. In addition, vimentin could be found in some basal cells of the terminal tubules of the fetal glands. Salivary neoplasms could be divided into three types with regard to their IFP pattern:  Acinic cell carcinomas showed a CK-pattern similar to normal acinar cells but a co-expression of CK and vimentin was present in some cells.  Adenoid cystic carcinomas, mixed tumours and basal cell adenomas showed a CK-pattern of normal duct or myoepithelial cells. The peri­pheral cells were also vimentin positive. 3. Mucoepidermoid carcinomas and adenocarcinomas had a similar CK-pattern as duct cells, and no tu­mour cells contained vimentin. This indicates that typing of IFP may be useful for subgrouping of salivary neoplasms. By stereological measurements, the cells of acinic cell carcinomas were found to be very similar to normal parotid acinar cells. Furthermore, they contained amylase and after stimulation by norepiphrine a secre­tory response was induced, with a rise in intracellular cAMP as well as a release of amylase. By single cell measurements of nuclear DNA con­tent, no difference was found between acinic cell carcinomas with de­finite metastasis and those without recurrence, both in paraffin sec­tions and cytological smears. / digitalisering@umu.se

Le tapis de nanotubes de carbone est un matériau intéressant pour des applications telles que les batteries, les piles à combustible ou les interconnexions en microélectronique. L’optimisation de la structure du tapis et de ses performances électriques pour une application donnée, envisageable si les mécanismes de croissance du tapis sont bien compris, est encore imparfaite aujourd’hui. L’équipe du CEA-Tech de Grenoble a modifié son procédé de dépôt CVD (Chemical Vapor Deposition en anglais) pour élargir la fenêtre des conditions de croissance et améliorer les performances des tapis de nanotubes en ajoutant des filaments chauds en carbone pour activer la phase gazeuse. Les travaux de cette thèse se sont orientés vers l’évaluation du rôle des filaments sur la croissance des tapis et l’impact qu’ils ont sur les performances électriques. Des méthodes d’analyse et des dispositifs expérimentaux dédiés ont été mis en place, pour pouvoir évaluer rigoureusement l’impact des filaments chauds sur la croissance des nanotubes. La synthèse de tapis de nanotubes de même structure avec et sans assistance des filaments a permis de démontrer que les filaments chauds ne modifiaient pas la cinétique de croissance mais allongeaient considérablement la durée de vie du catalyseur. Des tapis de nanotubes plus longs mais surtout avec une densité de nanotubes plus homogène en profondeur peuvent ainsi être obtenus, améliorant ainsi les performances électriques du tapis. Un modèle combinant propriétés électriques et cinétique de croissance est proposé pour interpréter les résultats / Carbon nanotubes forest have great potential in various electrical applications such as energy storage, microelectronic interconnects or electrical cable. These high-end applications however require control and tuning of the CNT structure and electrical performances which can only be achieved thanks to a good understanding of the growth mechanism. An original implementation of hot filament assisted CVD (Chemical Vapour Deposition) was developed at CEA-Tech in Grenoble to enlarge process window and improve the synthesis of carbon nanotube forest. This new method relies on the use of a parallel array of carbon hot filaments to activate the gas phase. The work of this thesis focused on the evaluation of the role of carbon filaments on CNT forest growth and electrical properties. Dedicated experimental methods and tools were developed to accurately assess the impact of hot filament assistance during CVD growth. By growing CNT forest of identical structures both with and without filament assistance, it is shown that hot filaments do not modify growth kinetics but drastically increase the catalyst lifetime. Thicker CNT forest with uniform density from top to bottom can thus be synthesized with this method. This translates into CNT forests with improved electrical performances. A model combining electrical properties with growth kinetics is introduced to quantitatively interpret our results