N-Acylethanolamines (NAEs) are enriched in seed-derived tissues and are believed to be formed from the membrane phospholipid, N-acylphosphatidylethanolamine (NAPE) via the action of phospholipase D (PLD). In an effort to identify a functional NAPE-PLD in cotton seeds and seedlings, we have screened a cotton seedling cDNA (cotyledon mRNA from 48 h dark grown seedlings) library with a 1.2 kb tobacco partial cDNA fragment encoding the middle third of a putative PLDβ/γ (genbank accession, AF195614) isoform. Six plaques were isolated from the Uni-ZAP lambda library, excised as pBluescript SK(-) phagemids and subjected to nucleotide sequence analysis. Alignment of derived sequences with Arabidopsis PLD family members indicated that the cDNAs represent six different PLD gene products -three putative PLD β isoforms and three putative PLD δ isoforms. The PLD β isoforms, designated Ghpldβ1a, GHpldβ1b and a truncated Ghpldβ1b isoform. Both the full-length PLD β proteins contained characteristic HKxxxxD catalytic domains, a PC-binding domain, a PIP2-binding domain and a C2 domain. In addition both cotton PLD β isoforms had a N-terminal "SPQY" rich domain which appeared to be unique to these PLDs. The three PLD δ isoforms, designated Ghpldδ1a, Ghpldδ1b and Ghpldδ1b-2 encode full-length PLDδ proteins, and like the above PLDs, contained the characteristic catalytic and regulatory domains. The expression of Ghpldδ1b showed hydrolytic and transphosphatidylation activity toward radiolabelled phosphatidylcholine (PC) but it appears Ghpldδ1b does not utilize NAPE as a substrate to produce NAEs nor does it seem to be suppressed by NAEs.

L’émergence de nouveaux matériaux structurés à l’échelle nanométrique, aux propriétés contrôlées, a ouvert de nouvelles perspectives vis-à-vis des matériaux qui nous entourent. C’est notamment le cas des métaux et de leurs alliages et il est crucial d’établir le lien entre leurs propriétés structurales et leurs propriétés chimique et physique pour en permettre une utilisation optimale. Cette thèse s’inscrit dans ce contexte et porte sur la synthèse et la caractérisation en microscopie électronique en transmission de nanoparticules d’alliage bimétallique Au-Cu. En s’appuyant sur le diagramme de phase décrit à l’échelle macroscopique, nous nous sommes particulièrement intéressés aux nanoparticules de compositions nominales Au3Cu, AuCu et AuCu3. Le premier axe de ce travail consiste en l’élaboration de nanoparticules d’alliage Au-Cu. Deux voies de synthèse sont explorées : la voie chimique reposant sur le procédé polyol et la voie physique par ablation par laser pulsé. Le premier mode d’élaboration permet l’obtention de nanoparticules parfaitement cubiques dont la composition est systématiquement riche en Au. Les nanoparticules produites par voie physique présentent en revanche une composition maitrisée et modifiable. D’un point de vue structural, un recuit de ces dernières particules mène à leur mise en ordre chimique et à l’observation de structures L10 et L12. Cependant, nous montrons que cette transition de phase est bloquée dans les nanostructures présentant des défauts structuraux. Enfin, l’évolution du paramètre de maille des nanoparticules synthétisées selon ces deux voies de synthèse, en fonction de leur composition, a été établie et suit exactement la loi de Vegard décrite pour le matériau massif.Dans un second temps, nous avons observé des nanoparticules obtenues par voie physique en microscopie électronique en transmission environnementale, c’est-à-dire dans des conditions proches des environnements d’utilisation habituellement appliqués en catalyse. Les expériences menées en température révèlent que le mécanisme de dissolution de nanoparticules d’Au et d’alliage Au-Cu portées à haute température se fait en deux étapes : il y a fusion des nanoparticules suivi de leur évaporation pour des tailles de nanoparticules centrées autour de 10 nm. Les expériences réalisées en couplant le chauffage des nanoparticules au passage d’un gaz (H2 ou O2), en flux et dans des conditions de pression bien supérieures à celles accessibles jusqu’à maintenant, ont permis d’étudier leur comportement thermodynamique en condition oxydantes et réductrices. Nous avons notamment montré que des cycles d’oxydo-réduction de nanoparticules de taille moyenne supérieure à 20 nm conduisent à un effet Kirkendall menant, de manière réversible, à la formation de nanoparticules creuses (doughnut). Cette thèse interdisciplinaire constitue travail pionnier dans la compréhension du système d’alliage bimétallique Au-Cu à l’échelle nanoscopique / The emergence of new materials, structured at the nanoscale, with controlled properties, has opened new prospects regarding materials around us. In particular for metals and alloys, it seems crucial to connect their structural properties to their chemical and physical properties in order to optimise their use.Within this context, this thesis is focused on the synthesis and the characterisation of Au-Cu bimetallic alloy nanoparticles by transmission electron microscopy. On the basis of the bulk phase diagram, we especially studied particles with nominal compositions Au3Cu, AuCu et AuCu3.The first part of this work is dedicated to the synthesis of nanoparticles in two different ways. The chemical way is based on the polyol process and leads to nanoparticles exhibiting a cubic shape, and a systematically rich Au content. On the other hand, nanoparticles obtained by Pulsed Laser Deposition (PLD), a physical method of synthesis, display a well-controlled and tuneable composition. From a structural point of view, the annealing of the particles leads to chemical order and the stabilisation of L10 and L12 structures. However, we reveal that this phase transition is blocked in nanostructures with crystal defects. Moreover, we establish the evolution of the lattice parameter of the particles as a function of the composition and we demonstrate that, as in the bulk case, it is in agreement with Vegard’s law.In the second part, the nanoparticles synthesised via the physical method are studied using environmental transmission electron microscopy, i.e. in conditions close to those usually applied in catalytic reactors. Experiments performed at high temperature highlight that the dissolution of Au and Au-Cu nanoparticles occurs in a two-step process: fusion occurs first and is followed by evaporation for nanoparticles with a mean diameter of 10 nm.Coupling heating with gas flow (H2 or O2) in higher pressure condition than those usually reached allows us to study the thermodynamic behaviour of the nanoparticles in oxidative or reductive conditions. Most Notably, we show that oxidation-reduction cycles performed on nanoparticles with a diameter larger than 20 nm leads to a Kirkendall effect and the reversible formation of hollow particles (doughnuts).This cross-disciplinary thesis is a pioneering work towards understanding the bimetallic Au-Cu alloy system at atomic scale

Cette thèse présente les résultats expérimentaux relatifs à l'étude des couches de GaN et de CuO déposées par la technique PLD (dépôt par laser à impulsions) sur des substrats de saphir, SrTiO3, quartz et MgO. Nous avons étudié les effets de plusieurs paramètres qui jouent sur la cristallisation et la morphologie des surfaces des films déposés, à savoir, la température du substrat, la pression au fond, la distance entre le substrat et la cible, la densité d'énergie du laser et la position du substrat. Les couches ont été caractérisées par XRD, microscopie à force atomique et Le microscope électronique à balayage, RHEED et RAMAN. Les résultats montrent que la rugosité et la qualité de la surface des films déposés par PLD dépendent de l'énergie cinétique de déposition des espèces chimiques. L'épaisseur du film, la cristallinité, l'homogénéité et la rugosité sont étroitement liés aux conditions de dépôt / The thesis presents experimental results related to the Pulsed Laser Deposition (PLD) of GaN and CuO thin films using sapphire, SrTiO3, quartz and MgO substrates. The evolution of crystallization and surface morphology of the as-deposited films were studied to investigate the influence of the process conditions such as: substrate heating, background pressure, target-substrate distance, laser energy density, and substrate location, which were systematically varied. The as-deposited films were characterized by X-ray diffraction, atomic force microscopy and scanning electron microscopy, X-ray photoelectron spectroscopy, RHEED and RAMAN techniques. The results convincingly demonstrate that the enhancement in film growth quality - the reduction in roughness and the delay of epitaxial breakdown - is related to the control of PLD species kinetics. The films thickness, crystallinity, homogeneity and surface roughness are strongly dependent on deposition conditions

The 5-HT2A receptor (5-HT2AR) is implicated in neuropsychiatric disorders such as schizophrenia and is thought to mediate the actions of a number of hallucinogenic and antipsychotic drugs. Additionally, certain polymorphic variants of the receptor, such as an allele resulting in substitution of amino acid 452 histidine (H) with tyrosine (Y), have been linked to schizophrenia or altered therapeutic response to antipsychotics. The 5-HT2AR utilises various intracellular signalling pathways, including the activation of phospholipase C (PLC) and phospholipase D (PLD) via recruitment of the small G-protein ADP-Ribosylation Factor (ARF). This thesis focusses on protein:protein interactions and signalling mechanisms of the 5-HT2AR and H452Y-5-HT2AR receptor variant. Both ARF1 and PLD1 have previously been shown to bind to the carboxy-terminal tail (ct) of the 5-HT2AR. In chapter three it is demonstrated that the 5-HT2AR can activate PLD in an ARF-dependent manner, primarily through the PLD1 isoform. GST-fusion proteins of truncated and mutated variants of the receptor ct are used to show that ARF1 and PLD1 independently bind to distinct sites. Coimmunoprecipitation, GST-fusion protein studies and PLD activity assays demonstrate that the introduction of the H452Y mutation decreases the physical interactions between the receptor and PLD1, as well as decreasing 5-HT2ARmediated PLD activation. In chapter four, potential mechanisms of wild-type and H452Y-5-HT2AR desensitisation are explored. It is shown that β-arrestin 2 (β-arr 2) confers a decrease in H452Y-5-HT2AR-mediated PLC activity, despite having no significant effect upon wild-type 5-HT2AR responses. The H452Y-5-HT2AR variant is also shown, by GST-fusion protein studies, to bind β-arr 2 more strongly. The H452Y-5-HT2AR additionally mediates increased levels of 5-HT-induced ERK phosphorylation compared to the wild type 5-HT2AR, potentially through increased scaffolding of ERK activation complexes by receptor-bound β-arr 2. Chapter five focusses on possible interactions of the 5-HT2AR with the Ca2+-binding proteins annexin A2, S100B and the annexin A2 partner p11, together with the functional consequences of these interactions. Co-immunoprecipiation and GST-fusion protein studies show that annexin A2 binds specifically to the 5-HT2AR ct. Furthermore, annexin A2 (but not S100B or p11) is shown to result in an amplification of 5-HT2AR-mediated PLC responses. These findings provide a greater insight into some of the signal transduction mechanisms of the 5-HT2AR and their perturbation in the H452Y polymorphic form of the receptor, and understanding of the molecular mechanisms underlying neuropsychiatric diseases in patient subgroups, potentially leading to improved therapeutic treatments.

Zinc oxide is a very versatile material that can be used in many microsystems and MEMS applications. ZnO thin film has been utilized in a wide variety of MEMS devices because of its unique piezoelectric, optical, and electrical properties. In particular, piezoelectric property of ZnO can be used in numerous applications from resonators and filters to mass sensors and micro-actuators (e.g., micro-valve and micro-pump). Because of its versatility, this research was focused on analyzing some key properties of ZnO thin film achieved by two different deposition techniques, Pulsed Laser Deposition (PLD) and Sputtering. Multiple experiments were conducted in order to identify the best conditions for the growth of ZnO thin film. Under the optimum conditions, the ZnO thin films will provide the best piezoelectric performance in devices such as microcantilevers. In order to find the best deposition conditions in both PLD and Sputtering multiple depositions have been done and then analyzed using the XRD, AFM, FTIR, nanoindenter, and ellipsometer. For the PLD the best conditions were found to be at 200°C with a partial pressure of O2 of 100 millitorr. For the sputtering system the best film formed when the substrate temperature was kept at 400°C along with RF power of 250 Watts, and a flow rate of 25% O2 and 75% Ar. Both experiments were similar in the fact that both a certain amount of O2 in the chamber and an elevated temperature are needed to facilitate the formation of ZnO crystal structure.

The dependence of dielectric permittivity on the applied electric field, high dielectric constant and low cost makes barium strontium titanate (BST) a promising ferroelectric material for applications in tunable microwave devices. High tunability and low dielectric loss is desired for tunable microwave devices. The primary objective of this research was to optimize the tunability and dielectric loss of BST thin films at microwave frequencies with different deposition techniques. Ba0.5Sr0.5TiO3 thin films were grown on Pt/TiO2/SiO2/Si, by pulsed laser deposition (PLD) and sputtering. Parallel plate capacitor structures were designed using ADS and fabricated. The microstructural and phase analysis of the BST films were performed using X-ray diffraction (XRD) method. The diffraction patterns are attributed to cubic (perovskite) crystal system. The analysis of surface morphology was done using atomic force microscopy. Electrical properties of parallel plate capacitors were measured using LCR meter and tunability of 2.4:1 and loss tangent of 0.05 was achieved at low frequencies for laser deposited BST thin films. Tunability of 2.8:1 and loss tangent of 0.03 was achieved at low frequencies for sputtered BST thin films. The correlation of optimized structural and dielectric properties of thin films deposited by pulsed laser deposition and sputtering technique was analyzed and compared. The structural characterization of sputtered BST thin film on MgO, Alumina and LaAl2O3 was achieved for the fabrication of interdigital capacitors. Interdigital capacitor has been designed using ADS momentum.

En los últimos años la comunidad científica ha realizado un esfuerzo importante en la búsqueda de nuevos materiales, con estructuras cada vez más complejas, que presenten a la vez propiedades de conducción mixta iónica y electrónica. Este tipo de materiales tienen aplicaciones en campos importantes de la tecnología como componentes de pilas de combustible de óxido sólido, membranas de permeación de oxígeno, o sensores de gas. De entre los materiales estudiados destacan los óxidos de metales de transición (Co, Mn, Ni, Fe,..) con estructura de tipo perovskita, y más recientemente, óxidos con estructura laminar derivada de la perovskita. Particularmente, en este último tipo de compuestos no existe todavía un conocimiento profundo de los mecanismos de transporte de carga, por lo se hace necesario un estudio fundamental en muestras de gran calidad cristalina. El objetivo principal de esta tesis es el estudio fundamental de las características estructurales y de las propiedades de transporte a altas temperaturas de películas delgadas del material Sr4Fe6O13 (que en adelante se denotará SFO), de estructura laminar derivada de la perovskita, obtenidas mediante la técnica de depósito por láser pulsado (PLD). La motivación principal de este estudio radica en el hecho de que, gracias al depósito en forma de lámina delgada epitaxial, es posible obtener una gran calidad cristalina, con un alto grado de control sobre la estructura de defectos en el material, y, por tanto, estudiar las propiedades de transporte, incluso en películas de espesores nanométricos. Del mismo modo el crecimiento epitaxial permitirá obtener un material altamente texturado gracias al que se pretende estudiar el grado de anisotropía en las propiedades de transporte inducida por la estructura laminar.La memoria se inicia, con una introducción general acerca de las películas delgadas y los conductores mixtos, poniendo especial énfasis en los mecanismos de transporte electrónico a alta temperatura. De igual modo se realiza una revisión bibliográfica exhaustiva relativa a la cerámica SFO y de la estructura perovskita relacionada SrFeO3. También se realiza una descripción del equipo de PLD empleado para el depósito de las películas, así como las diferentes técnicas utilizadas para la caracterización de los materiales estudiados. Posteriormente se aborda el estudio del crecimiento de las películas delgadas epitaxiales de SFO, así como un análisis estructural básico en función del espesor y del tipo de sustrato. Se estudian los cambios de los parámetros de red con el espesor y con diferentes tratamientos térmicos, en películas sobre distintos sustratos, con el objetivo de establecer las relaciones entre los parámetros de depósito y el estado de tensión de las películas. El análisis microestructural de estas películas es completado mediante técnicas de microscopia electrónica de transmisión en alta resolución, difracción de electrones y difracción de rayos X mediante radiación sincrotrón. Gracias a estas técnicas se ha desarrollado un modelo estructural para las películas, ligeramente diferente a los anteriormente reportados en la bibliografía, y que da lugar a una familia de compuestos Sr4Fe6O12+2?±?. Las observaciones experimentales sugieren un peculiar mecanismo de relajación de la tensión a través de la variación de la estructura modulada del material con el parámetro ?.Se concluye la caracterización de estas películas con el estudio de sus propiedades de transporte electrónico, a alta temperatura. El estudio consiste básicamente en medidas de la conductividad planar en películas de diferentes espesores, y bajo diferentes presiones parciales de oxígeno. De este modo se relacionan las variaciones en la dependencia de las curvas de conductividad con las diferentes características estructurales de las películas, y se establecen los posibles efectos de la reducción del tamaño a escala nanométrica. Por último se detallan las medidas de transporte a lo largo de la dirección perpendicular al plano de las películas, obteniendo una estimación de la anisotropía que presentan las propiedades de transporte de este material.En la memoria también se realiza la caracterización estructural y de propiedades de transporte de películas delgadas de la perovskita SrFeO3-?. Este estudio viene motivado por la posible influencia en la conductividad de la presencia de una interfase del material SrFeO3 observada en algunas ocasiones en las películas de SFO. Se realiza un análisis exhaustivo de sus propiedades de transporte, y se establece una comparativa entre ambos compuestos. Finalmente se aborda un estudio preliminar sobre el depósito de multicapas de SrTiO3/Sr4Fe6O13, con el objetivo de establecer el papel que juega en las propiedades de transporte electrónico la combinación de capas sucesivas de espesor nanométrico, así como la presencia de una mayor densidad de interficies. / In the last decades there has been an important activity in the research for new materials exhibiting high mixed oxygen-ion and electronic conductivities (MIEC) for electrochemical applications, such as for cathodes in solid oxide fuel cells, oxygen gas permeation membranes, and oxygen gas sensing. In order to lower the working temperature of such devices the thickness of the different components, such as electrolytes and electrodes, has been progressively reduced to a submicrometric scale to the point where classical thin film deposition techniques are required. On the other hand, recent studies have demonstrated that ionic conductivity can be enhanced in nano-structured materials by inducing strain or by introducing interfaces that can cause the redistribution of ions in the space-charged regions. Besides, the search for new perovskite-related MIEC materials has targeted complex oxides in the Sr-Fe-O system. In particular the intergrowth compound Sr4Fe6O13 has shown relevant ionic conductivity and enhanced stability. The objective of this work consists in preparing high quality epitaxial films of MIEC Sr4Fe6O13 that can be used in electrochemical devices. Since the transport properties of this layered compound are highly anisotropic, the measurements performed on epitaxial films provide a unique approach to study the intrinsic transport properties. In this work we present the results in the characterization of the high temperature conductivity of strained epitaxial Sr4Fe6O13 films. The epitaxial films have been prepared by pulsed laser deposition (PLD) technique. Different lattice strains have been obtained by varying the substrate mismatch or the thickness of the layers from a few nanometer to hundreds of nanometers. It has been shown that the total conductivity of MIEC films seems to increase by reducing its thickness. The influence of the lattice strain, combined with the presence of a peculiar modulated structure of the material, will be discussed in detail. On the other hand, measuring the conductivity along both directions, the conductivity anisotropy has been demonstrated.

abstract: Microwave dielectrics are widely used to make resonators and filters in telecommunication systems. The production of thin films with high dielectric constant and low loss could potentially enable a marked reduction in the size of devices and systems. However, studies of these materials in thin film form are very sparse. In this research, experiments were carried out on practical high-performance dielectrics including ZrTiO4-ZnNb2O6 (ZTZN) and Ba(Co,Zn)1/3Nb2/3O3 (BCZN) with high dielectric constant and low loss tangent. Thin films were deposited by laser ablation on various substrates, with a systematical study of growth conditions like substrate temperature, oxygen pressure and annealing to optimize the film quality, and the compositional, microstructural, optical and electric properties were characterized. The deposited ZTZN films were randomly oriented polycrystalline on Si substrate and textured on MgO substrate with a tetragonal lattice change at elevated temperature. The BCZN films deposited on MgO substrate showed superior film quality relative to that on other substrates, which grow epitaxially with an orientation of (001) // MgO (001) and (100) // MgO (100) when substrate temperature was above 500 oC. In-situ annealing at growth temperature in 200 mTorr oxygen pressure was found to enhance the quality of the films, reducing the peak width of the X-ray Diffraction (XRD) rocking curve to 0.53o and the χmin of channeling Rutherford Backscattering Spectrometry (RBS) to 8.8% when grown at 800oC. Atomic Force Microscopy (AFM) was used to study the topography and found a monotonic decrease in the surface roughness when the growth temperature increased. Optical absorption and transmission measurements were used to determine the energy bandgap and the refractive index respectively. A low-frequency dielectric constant of 34 was measured using a planar interdigital measurement structure. The resistivity of the film is ~3×1010 ohm·cm at room temperature and has an activation energy of thermal activated current of 0.66 eV. / Dissertation/Thesis / M.S. Materials Science and Engineering 2013

Nano structured wide band gap semiconductors have attracted attention of many researchers due to their potential electronic and optoelectronic applications. In this thesis, we report successful synthesis of well aligned Eu doped ZnO nano-rods prepared, for the first time to our knowledge, by pulsed laser deposition (PLD) without any catalyst. X-ray diffraction (XRD) patterns shows that these Eu doped ZnO nanorods are grown along the c-axis of ZnO wurtzite structure. We have studied the effect of the PLD growth conditions on forming vertically aligned Eu doped ZnO nanorods. The structural properties of the material are investigated using a -scanning electron microscope (SEM). The PLD parameters must be carefully controlled in order to obtain c-axis oriented ZnO nanorods on sapphire substrates, without the use of any catalyst. The experiments conducted in order to identify the optimal growth conditions confirmed that, by adjusting the target-substrate distance, substrate temperature, laser energy and deposition duration, the nanorod size could be successfully controlled. Most importantly, the results indicated that the photoluminescence (PL) properties reflect the quality of the ZnO nanorods. These parameters can change the material’s structure from one-dimensional to two-dimensional however the laser energy and frequency affect the size and the height of the nanorods; the xygen pressure changes the density of the nanorods.

Title: Characterization and focusing of capillary-discharge XUV-laser beam for purposes of thin-film deposition Author: Peter Pira Department: Department of Surface and Plasma Science Supervisor: doc. RNDr. Jan Wild, CSc., Department of Surface and Plasma Science Abstract: The paper deals with the first results of the interaction of a desk-top high repetition rate XUV laser (wavelength of 46.9 nm) radiation with materials suitable for optoelectronics, in particular the ionic crystals CsI, LiF, etc. Using surface physics methods (AFM, DIC Normanski microscopy) pulse laser imprints were investigated. Based on the results obtained, general information on the nature of ablation and desorption was obtained, which were compared with the results of the XUV-ABLATOR modified code modeling. Plasma arising from ablation was examined by a modified Langmuir probe system. The main result is the pulse laser deposition of thin films of Bi and CsI. Keywords: ablation, Pulsed Laser Deposition, XUV laser