The present thesis deals with Nb-Si alloy composites in both bulk and multilayer forms. The work has been divided into two parts. First part (chapter 4-6) deals with Nb based silicides binary and ternary alloys with alloying additions like Ga and Al. These alloys are synthesized by vacuum arc melting and suction casting (non-equilibrium processing techniques). The studies on intermetallic coatings of Nb-Si alloys and Nb/Si multilayer synthesized by pulsed laser deposition technique have been presented in the second part (chapter7-8). Nb-Si alloys are one of the candidate materials for the advanced structural and microelectronic applications. There are few issues with these materials like poor oxidation resistance, low fracture toughness and brittleness which need to be solved. Microstructure plays a crucial role to control these properties. The main focus of this work is to understand the process of phase transformation and thereby control the microstructure in both bulk alloys and thin films. We have also investigated in a limited manner mechanical and environmental properties of bulk alloys. This thesis is subdivided into nine chapters. After a brief introduction in the first chapter, a brief overview on Nb-Si phase diagram and literature reviews on Nb-Si based alloys are presented with emphasis on the current work in the second chapter. Literature reviews on the phase formations sequence and stability in Nb-Si alloys thin films and Nb/Si multilayers are also discussed in the same chapter. In the third chapter different experimental techniques, processing parameters and characterization tools like XRD, SEM, TEM etc. are briefly discussed. Special emphasis is given on two non-equilibrium techniques: laser deposition technique to deposit the thin film/multilayer and vacuum suction casting to produce the 3 mm diameter rods of different Nb-Si alloys. The fourth chapter discusses the microstructural aspects of Nb-Si alloys prepared by suction casting and its mechanical behavior. The samples have the compositions hypoeutectic (Nb-10at.%Si and Nb-14at.%Si), eutectic (Nb-18.7at.%Si) and hypereutectic (Nb-22at.% Si and Nb-25at.% Si). SEM microstructural analyses of all the samples clearly show the enhancement in the volume fraction of eutectic and decease in the eutectic spacings in microstructure due to large undercooling. Rod eutectic is observed in most of places with irregular eutectic a few places in all samples. First check of phases has been done by XRD in all samples. Phase confirmation using TEM showed the eutectic between Nbss and Nb3Si phases in all samples. The primary phase for hypoeutectic alloys is Nbss (dendritic structure), Nb3Si phase for eutectic composition and β-Nb5Si3 phase for hypereutectic alloys. Compositional analysis using EDS and EPMA also supported the above results. No signature of eutectoid reaction (Nb3Si→Nb+α-Nb5Si3) is observed. Mechanical properties like hardness, strength, ductility and indentation fracture toughness have been determined for above mention alloy compositions. SEM micrographs showed that silicides fractured by cleavage and Nb phase in a ductile manner during the compression tests carried out at room temperature. We attempt to explain how the above mention mechanical properties change with alloy compositions and processing. Chapter five deals with the effect of Ga addition on the microstructure and mechanical properties of the Nb-Si alloy. The composition selected for this study is Nb-20.2at.%Si-2.7at.%Ga. The results of ternary alloy have been compared with the binary alloy composition Nb-18.7at.%Si. Phase analysis has been carried out using TEM and XRD. Ga addition has suppressed the formation of Nb3Si phase and promoted the formation of β-Nb5Si3 phase. Ga addition also established the eutectic between Nbss and β-Nb5Si3, which is a metastable eutectic. Ga added ternary alloy, on suction casting, yields ultrafine eutectic with nanometer length scale (50-100nm). From the compression tests, it is concluded that the combination of ultrafine eutectic (Nbss-β-Nb5Si3) and primary β-Nb5Si3 in ternary alloy results in a high compressive strength ~2.8±0.1 GPa with 4.3% plasticity. In contrast binary alloy under identical conditions shows the compressive strength ~1.35±0.1 GPa and 0.2% plasticity. Ga addition also enhances the indentation fracture toughness from 9.2±0.05 MPa√m (binary) to 24.11±0.5 MPa√m (ternary). Composite hardness values of the ternary and binary alloys are 1064±20 Hv and 1031±20 Hv respectively. Chapter six deals with Al added Nb-Si ternary alloy. Here we have discussed microstructural and mechanical properties like in chapter 5 along with oxidation behavior for the alloy composition Nb-12.7at.%Si-9at.%Al. SEM micrograph shows the presence of primary dendrites structure with ultra fine lamellar eutectic (50-100nm). Detailed TEM studies confirm the Nbss as primary phase present in form of dendrites. These dendrites contain the plate shape precipitates of δ-Nb11Si4 (body centered orthorhombic structure) phase in Nb matrix (primary dendrites). Eutectic phases are Nbss and β-Nb5Si3. The analysis of the results indicates that Al addition promote the formation of β-Nb5Si3 phase in the eutectic. The results of this ternary composition were also compared with the binary alloy composition Nb-18.7at.%Si. Compression tests have been carried out at room and elevated temperatures to measure the strength of the material. Al added ternary alloy yields the compressive strength value 1.6±0.01 GPa whereas binary alloy yields the compressive strength value 1.1±0.01 GPa. Enhancement in indentation fractured toughness is observed in Al added ternary alloy (20.4±0.5MPa√m) compare to binary alloy (9.2±0.05 MPa√m). Thermal analysis by TGA and DTA were used to see the oxidation behavior of Al added ternary alloy. Chapter seven deals with the deposition characteristics and the TEM studies on the laser deposited Nb-Si thin films. Films were deposited on the NaCl crystals and Si single crystal substrates. The compositions chosen in this case are Nb-25at.%Si, Nb-37.5at.%Si and Nb-66.7at.%Si. These compositions correspond to the equilibrium intermetallic compounds Nb3Si, Nb5Si3 and NbSi2 respectively. In this chapter we have briefly discussed the microstructural and phase evolutions in the intermetallic coatings. The smooth films quenched from the vapor and/or plasma state show amorphous structure. The sequence of crystallization was studied by hot stage TEM experiments as well as by cross sectional TEM in the films deposited at the elevated temperatures (600oC and 700oC) on Si substrates. During the hot stage experiment, crystallization is observed in Nb-25at.%Si film around 850oC with nucleation of metastable cubic Nb3Si phase. Occasionally metastable hexagonal Nb3Si3 phase has also been observed (close to Si substrate) along with cubic Nb3Si phase in the films at elevated temperatures. For Nb-37.5at.%Si film, crystallization is observed at 800oC with the nucleation of grains of metastable hexagonal Nb5Si3 phase. Cross-sectional TEM shows the presence of hexagonal Nb5Si3 phase along with few grains of NbSi3 (equilibrium) phase in the films deposited at elevated temperatures. Hot stage experiment of Nb-66.3at.%Si film showed the onset of crystallization much earlier at 400oC and complete crystallization at 600oC. This crystallization leads to the nucleation of grains of NbSi2 phase. Films of this composition deposited at elevated temperatures showed the presence of NbSi2 and metastable hexagonal Nb5Si3 phases (occasionally). The laser ablated films, besides the film matrix also contain the micron and submicron sized spherical droplets of different sizes. These droplets travel at very high velocities and impinge on the substrate resulting in a very high rate of heat transfer during solidification from liquid state. Therefore in this work we have also studied the microstructural evolution in the droplets for each composition. The phases observed in the droplets embedded in the matrix of Nb-25 at% Si alloy film are the bcc Nb and the cubic Nb3Si (metastable phase). The droplets in the matrix of Nb-37.5 at% Si alloy showed the bcc Nb and tetragonal β-Nb5Si3 phases. The phases observed in the droplets of in the Nb-66.3at.%Si alloy are the bcc Nb, tetragonal β-Nb5Si3 and the hexagonal NbSi2 (metastable phase). Chapter eight describes the synthesis and microstructural characterization using TEM of Nb/Si multilayers. The aim of this work is to check the stability and phase formation sequence in Nb/Si multilayer. Nb/Si multilayers were first annealed at different time intervals at 600oC and at different temperatures (for 2 hours) and then characterized by the cross-sectional transmission electron microscopy. As-deposited Nb layer is crystalline while Si layer is amorphous. Microstructural and compositional evidences suggest the intermixing between the Nb and Si layers at the interfaces. Nb/Si multilayer annealed at 600oC for 1 hour, NbSi2 was identified as the first crystalline nucleating phase. However amorphous silicide layers were also observed between Nb and NbSi2 layers. Metastable hexagonal Nb5Si3 was identified as the next crystalline phase that nucleated from the amorphous silicide layers at the interfaces of Nb and NbSi2 layers. Occasionally few grains of cubic Nb3Si phase were also observed after 8 hours of annealing at 600oC. In the chapter we have compared the results to the other reported works in Nb-Si bulk diffusion couples and also thin film couples. The final chapter summarizes the major conclusions of the present work and scope of future work.

L’immunité végétale est garantie par plusieurs niveaux d’action dont l’interconnexion et les voies signalétiques sont peu élucidées. Deux des trois couches de défenses immunitaires sont constituées par les protéines NB-LRR (Nucleotide-Binding Leucine-Rich Repeat), encodées par les gènes de Résistance (gènes R), et l’interférence à ARN (iARN). L’étude de la voie de signalisation induite par l’activation des NB-LRR en réponse à la reconnaissance (directe ou indirecte) de protéines pathogéniques est très compliquée, car cette réponse culmine, dans la majeure partie des cas, en un phénotype macroscopique de mort cellulaire dénommée Réponse hypersensible (HR), empêchant toute analyse biochimique. Récemment, il a été montré chez Nicotiana benthamiana que la réponse antivirale déclenchée par la protéine NB-LRR N, qui n’induit pas de HR lorsqu’activée, implique la répression de la traduction de l’ARN viral. Dans ce système, la résistance conférée par N est dépendante de la protéine AGO4 dont le rôle dans l’iARN est assez bien défini. En effet, bien que l’ARN viral se multiplie à l’intérieur de la cellule hôte, il n’est pas associé à la machinerie de traduction et ne produit donc plus de virions. Cependant, nous ne connaissons pas à ce jour les évènements de régulation de l’expression génique responsables de ce mécanisme de défense. Les études du transcriptome immunitaire chez Arabidopsis thaliana n’ont révélé que peu de candidats majeurs impliqués dans la réponse NB-LRR, alors que certaines études mettent en lumière l’implication de la régulation de l’expression génique, au niveau traductionnel, dans la réponse immunitaire. En s’appuyant sur les travaux de Bhattacharjee et al. (2009), nous avons entrepris de caractériser, au niveau cellulaire, la répression de la traduction de l’ARN viral pendant la réponse induite par N. Nous observons, dans un système inductible permettant de déclencher la réponse immunitaire après l’établissement de l’infection virale, une large formation de granules à ARN appelés PBs (Processing Bodies), en conséquence de l’inhibition spécifique de la traduction de l’ARN viral. Le mécanisme effecteur de cette répression est différent des mécanismes de répression traductionnelle mis en place en réponse à la perception de stress tel que les UVs, ou de l’induction des mécanismes de répression traductionnelle par l’iARN. De plus, des plantes d’Arabidopsis mutantes pour une protéine fonctionnant dans les PBs sont plus résistantes à des bactéries phytopathogènes. D’une façon intéressante, on détecte un niveau d’expression augmenté de certains gènes de défense dans ce mutant, de manière similaire à des mutants d’Arabidopsis compromis dans l’une des voies de dégradation des ARNm. En parallèle, nous avons développé des outils transgéniques pour déterminer si la régulation de la traduction des ARNm de l’hôte, à l’échelle génomique, joue un rôle dans l’établissement de l’immunité. Nous avons généré une lignée d’Arabidsopsis exprimant sous le contrôle d’un promoteur inductible le facteur d’Avirulence (Avr) AvrRpm1, dont la présence est reconnue par la protéine NB-LRR RPM1; en combinaison avec une protéine ribosomale étiquetée nous permettant d’immunopurifier les ribosomes avec les ARNm en cours de traduction. Le séquençage à haut-débit des ARN totaux et des ARNm engagés dans la traduction a révélé que cinq fois plus de gènes sont régulés au niveau traductionnel par rapport au niveau transcriptionnel, après l’induction de la réponse NB-LRR. Une analyse comparée avec les connaissances précédentes a révélé que la réponse NB-LRR induit l’expression de 20% des gènes NB-LRR totaux, qui sont aussi constitutivement exprimés dans des mutants compromis dans certains processus de dégradations des ARNm. Cependant, la réponse NB-LRR induit l’expression de centaines de gènes précédemment impliqués dans les défenses, ce qui n’est pas le cas dans les mutants de dégradation d’ARNm, soulignant ainsi la spécificité de la réponse NB-LRR. Une analyse bio-informatique a déterminé qu’environ cinq cent gènes sont régulés au niveau traductionnel de manière indépendante de leur abondance totale, fournissant une liste de nouveaux candidats potentiellement impliqués dans l’immunité NB-LRR et spécifiquement régulés au niveau traductionnel. Une analyse génétique de certains mutants de ces gènes candidats dans les défenses a été entreprise, et a révélé que des plantes d’Arabidopsis TOR-déficientes ou mutantes pour les gènes CIPK5, CCT2 et BIG possèdent une résistance altérée positivement pour les TOR-déficientes ou négativement pour les autres, par rapport à une plante sauvage. Dans leur ensemble, ces résultats prouvent une grande implication de la régulation de la traduction dans la mise en place de l’immunité végétale.

No description available.

O presente trabalho está relacionado a estudos de superligas à base de Ni, cujas microestruturas multifásicas apresentam propriedades satisfatórias para aplicações em altas temperaturas. O Nb e o Ta são componentes importantes nesta classe de materiais, estando normalmente associados às fases endurecedoras ?\' e \'\'. Desta forma, a determinação das relações de fases no sistema Ni-Nb-Ta na região rica em Ni corresponde a uma importante contribuição para a literatura referente, especialmente para os trabalhos ligados à construção de base de dados termodinâmicos. Assim, foi definido como objetivo principal a proposição das relações de fases na região rica em Ni do sistema Ni-Nb-Ta para a temperatura de 1050oC. As ligas foram obtidas por fusão a arco e tradas termicamente a 1050ºC por no mínimo 120 h. Amostras no estado bruto de fusão e tratadas termicamente foram caracterizadas microestruturalmente (MEV e DRX) e por microanálise química (EDS). Na região de estudo, observou-se as fases Niss, Ni8Ta, Ni3(Nb,Ta), Ni2(Nb,Ta), e ? (NiTa; Ni6Nb7), sem a presença de qualquer fase ternária. Observou-se uma solubilidade completa de Nb e Ta nas fases Ni3(Nb,Ta) e ?. A fase Ni2Ta apresentou uma solubilidade de Nb próxima de 13% at. Não foi possível determinar a região de solubilidade de Nb na fase Ni8Ta. / This work is related to studies of Ni-based superalloys, which multiphase microstructures have satisfactory properties for high temperature applications. The Nb and Ta are important components in this class of materials and is typically associated with the hardening phases ? \' and .\'\' Thus, the determination of phase relationships in the system Ni-Nb-Ta in the Ni-rich region represents an important contribution to the literature, especially for determination of related thermodynamic data. Thus, the main objective of this work was to propose the phase relationships in the Ni-rich region of the system Ni-Nb-Ta at 1050oC. The alloys were obtained by arc melting and heat-treated at 1050 º C for at least 120 h. Samples in the a-scast and heat treated states were characterized via (SEM and XRD) and chemical microanalysis (EDS). In the region of study, the observed phases were Niss, Ni8Ta, Ni3(Nb, Ta), Ni2(Nb,Ta), and ? (NiTa; Ni6Nb7) without the presence of any ternary phase. There was a complete solubility of Nb and Ta in the Ni3(Nb,Ta) and ? phases. The Ni2Ta showed a solubility of Nb close to 13% at. It was not possible to determine the region of solubility of Nb in the Ni8Ta phase.

This thesis examines the ways in which the unique creativity brought to late Victorian applied art by the Della Robbia Pottery was a consequence of Harold Rathbone’s extended engagement with quattrocento ceramics. This was not only with the sculpture collections in the South Kensington Museum but through his experiences as he travelled in Italy. In the first sustained examination of the development of the Della Robbia Pottery within the wider histories of the Arts and Crafts Movement, the thesis makes an original contribution in three ways. Using new sources of primary documentation, I discuss the artistic response to Italianate style by Rathbone and his mentors Ford Madox Brown and William Holman Hunt, and consider how this influenced the development of the Pottery. Rathbone’s own engagement with Italy not only led to his response to the work of the quattrocento sculptor Luca della Robbia but also to the archaic sgraffito styles of Lombardia in Northern Italy. Thirdly, the thesis identifies how the Della Robbia Pottery established a commercial presence in Regent Street and beyond, demonstrating how it became, for a short time, an outstanding expression of Italianate style within the British Arts and Crafts Movement.

O presente trabalho está relacionado a estudos de superligas à base de Ni, cujas microestruturas multifásicas apresentam propriedades satisfatórias para aplicações em altas temperaturas. O Nb e o Ta são componentes importantes nesta classe de materiais, estando normalmente associados às fases endurecedoras ?\' e \'\'. Desta forma, a determinação das relações de fases no sistema Ni-Nb-Ta na região rica em Ni corresponde a uma importante contribuição para a literatura referente, especialmente para os trabalhos ligados à construção de base de dados termodinâmicos. Assim, foi definido como objetivo principal a proposição das relações de fases na região rica em Ni do sistema Ni-Nb-Ta para a temperatura de 1050oC. As ligas foram obtidas por fusão a arco e tradas termicamente a 1050ºC por no mínimo 120 h. Amostras no estado bruto de fusão e tratadas termicamente foram caracterizadas microestruturalmente (MEV e DRX) e por microanálise química (EDS). Na região de estudo, observou-se as fases Niss, Ni8Ta, Ni3(Nb,Ta), Ni2(Nb,Ta), e ? (NiTa; Ni6Nb7), sem a presença de qualquer fase ternária. Observou-se uma solubilidade completa de Nb e Ta nas fases Ni3(Nb,Ta) e ?. A fase Ni2Ta apresentou uma solubilidade de Nb próxima de 13% at. Não foi possível determinar a região de solubilidade de Nb na fase Ni8Ta. / This work is related to studies of Ni-based superalloys, which multiphase microstructures have satisfactory properties for high temperature applications. The Nb and Ta are important components in this class of materials and is typically associated with the hardening phases ? \' and .\'\' Thus, the determination of phase relationships in the system Ni-Nb-Ta in the Ni-rich region represents an important contribution to the literature, especially for determination of related thermodynamic data. Thus, the main objective of this work was to propose the phase relationships in the Ni-rich region of the system Ni-Nb-Ta at 1050oC. The alloys were obtained by arc melting and heat-treated at 1050 º C for at least 120 h. Samples in the a-scast and heat treated states were characterized via (SEM and XRD) and chemical microanalysis (EDS). In the region of study, the observed phases were Niss, Ni8Ta, Ni3(Nb, Ta), Ni2(Nb,Ta), and ? (NiTa; Ni6Nb7) without the presence of any ternary phase. There was a complete solubility of Nb and Ta in the Ni3(Nb,Ta) and ? phases. The Ni2Ta showed a solubility of Nb close to 13% at. It was not possible to determine the region of solubility of Nb in the Ni8Ta phase.

This diploma thesis deals with the design of low-power IoT device communicating by using the NB-IoT standard. The theoretical part of the thesis is dedicated to the explanation of the principles and capabilities of communication in IoT networks Sigfox, LoRa and NB-IoT, and also its physical layer, network architecture, techonology principles and frequency bands used. The application part of the thesis is dedicated to design of the NB-IoT device from the system design through the selection of main components to the detailed physical design of the device. Two prototypes of the device with two different radio modules used are fabricated on which is performed measurement of the power profile of the device in various operation modes.

Some individuals and older adults have trouble remembering when to take their medication. A medication dispenser machine is one suggested solution to this problem. The purpose of this thesis is to design a prototype of a wireless machine for storing and releasing patients’ medication dosages at a certain time. The user can insert the medication schedule through a platform connected to the machine via wireless technology. In order to achieve the purpose, a literature study was conducted to gather and analyze information about wireless communication technologies to determine the most appropriate wireless technology for the thesis end device. The Arduino MKR NB 1500 is the core component of the prototype of the wireless system. Several types of tests were conducted on the system to evaluate its performance, as well as to determine NB-IoT coverage in real-world scenarios. The NB-IoT technology was proven to be the more suitable technology for the wireless pill dispensing machine and for other IoT applications. Moreover, the system performed satisfactorily in solving the defined problem. Despite this, the system could be improved in terms of design, mechanisms, and hygiene system of medicines. / Vissa människor eller äldre vuxna har svårighet att komma ihåg att ta sin medicin och hantera dem själva. En medicindispenser maskin är den föreslagna lösningen för detta problem. Syftet med detta examensarbete är att designa en prototyp av en trådlös maskin för att lagra och frigöra patienternas läkemedelsdoser vid en viss tidpunkt. Användaren kan infoga medicinschemat via en plattform ansluten till maskinen med hjälp av en lämplig trådlös teknik. För att uppnå syftet genomfördes en litteraturstudie för att samla in och analysera information om trådlös kommunikationsteknik för att bestämma den mest lämpliga trådlösa tekniken för arbetets slut enhet. Arduino MKR NB 1500 är kärnkomponenten i prototypen av det trådlösa systemet. Flera typer av tester utfördes på systemet för att utvärdera dess prestanda, samt för att fastställa NB-IoT-täckning i verkliga scenarier. NB-IoT tekniken har visat sig vara den mer lämpliga tekniken för den trådlösa medicindispenser maskinen och för andra IoT-applikationer. Dessutom fungerade systemet tillfredsställande för att lösa det definierade problemet. Trots detta skulle systemet kunna förbättras när det gäller design, mekanismer och hygiensystem för läkemedel.

Le système immunitaire végétal se base sur la présence de récepteurs intracellulaires de type NB-LRR afin de se défendre contre les pathogènes. Un NB-LRR active la réponse immunitaire suite à la détection de protéines d’origine pathogénique nommées effecteurs. Les NB-LRR se divisent en différents groupes selon le domaine N-terminal qu’ils possèdent soit un CC, un TIR ou un CC[indice inférieur R]. Les CC[indice inférieur R]-NB-LRR forment une famille atypique de NB-LRR qui se divise elle-même en deux groupes, les ADR1-like et les NRG1-like. Contrairement aux NB-LRR dits classiques, les CC[indice inférieur R]-NB-LRR ne détectent pas d’effecteurs provenant des pathogènes. En fait, les CC[indice inférieur R]-NB-LRR seraient des NB-LRR auxiliaires nécessaires à la cascade de signalisation de la réponse immune, enclenchée suite à la détection d’un effecteur par un NB-LRR classique. Les CC[indice inférieur R]-NB-LRR se distinguent également des NB-LRR classiques de par leur niveau de conservation chez les végétaux : chaque plante possède au minimum un type de CC[indice inférieur R]-NB-LRR. Alors qu’ADR1-like est ubiquitaire chez les monocotylédones et les dicotylédones, NRG1-like est absent du génome des monocotylédones et de quelques dicotylédones. L’absence de NRG1-like corrèle avec l’absence de TIR-NB-LRR dans ces génomes et propose un lien fonctionnel exclusif entre les NRG1-like et les TIR-NB-LRR. L’omniprésence du groupe ADR1-like et des CC-NB-LRR suggère aussi un lien fonctionnel entre ces deux groupes. Il est toutefois possible que la fonction de NB-LRR auxiliaire des groupes ADR1-like et NRG1-like soient partiellement redondante, ou additive, pour la réponse immune. Afin de confirmer la nécessité des CC[indice inférieur R]-NB-LRR pour les réponses de défenses médiées par les NB-LRR et pour en plus discriminer les besoins entre les groupes ADR1-like et NRG1-like, des mutants adr1 ou nrg1 ont été testés quant à leur capacité à compléter la réponse de défense initiée par différents NB-LRR classiques. Les résultats préliminaires suggèrent que le groupe ADR1-like n’est pas nécessaire pour les réponses de défense médiée par les TIR-NB-LRR RPS6 chez Arabidopsis thaliana et N chez Nicotiana benthamiana. L’absence de l’un des deux représentants NRG1-like d’Arabidopsis thaliana, soit NRG1.1 ou NRG1.2, n’affecte aucune réponse de défense médiée par un TIR-NB-LRR ou un CC-NB-LRR. L’homologie élevée de 73% entre ces deux protéines indique possiblement une fonction redondante. Un double mutant nrg1 a été produit afin de poursuivre l’investigation de la fonction du groupe NRG1-like dans les réponses de défense. Puisque les gènes NRG1.1 et NRG1.2 sont arrangés en tandem dans le génome d’Arabidopsis thaliana, une méthode optimisée permettant de sélectionner un événement de recombinaison méiotique rare entre deux allèles mutantes nrg1.1 et nrg1.2 a été choisie pour produire le double mutant. Avec une méthode indirecte, il a été démontrée que la lignée AB possède un évènement de recombinaison entre ces deux allèles mutantes puisqu’une plante double mutant nrg1 homozygote a été récupérée dans sa progéniture. Les résultats préliminaires obtenus avec cette plante double mutant nrg1 homozygote suggèrent que le groupe NRG1-like serait nécessaire pour la réponse de défense médiée par le TIR-NB-LRR RPS4 et suggèrent également qu’une plante dépourvue de NRG1-like aurait un phénotype de croissance retardée ou ralentie, en plus d’une morphologie foliaire distincte. Il est également connu que le domaine N-terminal CC[indice inférieur R] des CC[indice inférieur R]-NB-LRR d’Arabidopsis thaliana peut à lui seul induire une réponse de défense lorsque surexprimé chez N.benthamiana. Afin de trouver des protéines interagissant avec ce domaine et de caractériser sa localisation cellulaire, des plantes d’Arabidopsis thaliana transgéniques surexprimant le domaine CC[indice inférieur R] de NRG1.1 couplé à la eYFP:HA ont été produites. Le matériel obtenu permettra spécialement de poursuivre la caractérisation du groupe NRG1-like sur lequel peu d’information est disponible à ce jour. Il sera également possible de déterminer le niveau de redondance entre les deux groupes de CC[indice inférieur R]-NB-LRR quant à leur nécessité pour les réponses de défenses médiées par les NB-LRR suite à la production d’un quintuple mutant adr1/nrg1 d’Arabidopsis ne possédant plus aucun CC[indice inférieur R]-NB-LRR.

Foi estudado o efeito do hidrogênio dissolvido intersticialmente em ligas de nióbio-titânio e nióbio-zircônio. Nas ligas de nióbio-titânio, foram efetuadas medidas de decremento logarítmico por intermédio de medidas de atrito interno em um pêndulo de torção oscilando com freqüência em torno de 4.0 Hz, para amostras puras e dopadas com hidrogênio. Os resultados mostraram a interação do hidrogênio com a matriz metálica através do Efeito Gorsky. Nas ligas de nióbio-zircônio, foram efetuadas medidas de atenuação ultra-sônica para freqüências de 10 e 30 MHz, em amostras puras, contendo hidrogênio e contendo oxigênio e hidrogênio. Os resultados mostraram a interação do hidrogênio com a matriz metálica através de um processo de reorientação induzida por tensão de átomos de hidrogênio localizados em sítios intersticiais tetraedrais em torno de átomos de oxigênio congelados em sítios intersticiais octaedrais, próximos de átomos de nióbio da matriz metálica. / We study the effect of hydrogen dissolved interstitially in niobium-titanium and niobium-zirconium alloys. In the niobimn-titanium alloys, the logarithmic decrement was studied by internal friction measurements in a torsion pendulum with frequency about 4.0 Hz, on pure and hydrogen doped samples. Our results showed the interaction of hydrogen with the metallic matrix by the Gorsky effect. In the niobium-zirconium alloys, the ultrasonic attenuation was measured by the echo-pulse method with frequencies of 10 and 30 MHz, for pure, doped with hydrogen and doped with oxygen and hydrogen. The results have shown the interaction of hydrogen with the metallic matrix by a stress induced ordering of hydrogen atoms localized at tetrahedral sites around frozen oxygen atoms localized in the octahedral sites near the niobium atoms in the metallic matrix.