Les progrès de la fabrication additive (polymère ou métal) ont réanimé l’intérêt pour les matériaux architecturés de type treillis. Nous avons choisi d’étudier les réseaux bi-dimensionnels réguliers les plus simples et constitués de triangles. Les cotés des triangles sont modélisés par des barres en supposant les jonctions articulées ou des poutres pour des jonctions rigides. Une structure en treillis peut être définie comme la combinaison d’un réseau et d’un motif où le motif représente l’épaisseur des barres aux sommets du triangle. Toutes les combinaisons possibles de réseaux triangulaires et de motifs en 2D sont étudiées. En 2D, le tenseur d’élasticité possède 4 groupes de symétrie qui peuvent être distingués en utilisant les invariants de Viannello. À l’aide de ces invariants, nous avons calculé les relations (géométriques et mécaniques) que doivent satisfaire les barres et les poutres pour chaque groupe de symétrie. La thèse confirme le résultat connu qu’une structure de barre ne peut représenter que l’élasticité de type Cauchy (matériaux pour lesquels C1122 = C1212) alors qu’une structure de poutres est des plus générales. On montre finalement qu’en choisissant des raideurs de barres ou de poutres appropriées, il est possible d’obtenir une classe de symétrie élastique supérieure à la symétrie du réseau seul. / Néant

2-Dimensional (2D) materials are characterised by atomic thickness and significantly larger edge-lengths, producing particles which are highly confined in 1 direction. Reducing a material to one or few atomic layers gives rise to structural and electronic properties that deviate significantly from those of the bulk crystal. For this reason 2D nanosheets have been investigated for potential application in sensing, catalysis, capacitance, photovoltaics and for flexible circuits (among others).Despite rapid progress in understanding the synthesis and properties of 2D nanosheets in recent years, there remain significant problems surrounding the development of scalable production methods, understanding and tuning fundamental properties, and controlling the size and monodispersity of semiconductor crystals. In addition, new materials with novel properties are constantly sought in order to meet specific requirements. Although the tools developed over the last 12 years can often be applied to the fabrication of these materials, understanding their behaviour and limitations is ongoing. The following thesis discusses the routes to the fabrication of 2-dimensional materials and explores the production of MoS2, black phosphorus and tin(II) sulfide nanosheets. The aim of each piece of work is determined by the level of development of the field; MoS2 nanosheets have been known for several years and therefore the work presented was motivated by a desire to impart size control for specific applications. The study of phosphorene and 2D tin(II) sulfide is in its infancy; as such the focus remains on scalable nanosheet exfoliation and developing an understanding of their properties. The following studies on phosphorene report the exfoliation of nanosheets in organic and aqueous surfactant solutions and an investigation of the stability and breakdown products of the resulting colloidal suspensions. The stabilisation of phosphorene in aqueous media paves the way for its use in biological systems. Band-gap tuning in IV-VI analogues of phosphorene is demonstrated by size-selection of exfoliated SnS nanosheets. Although the physical characteristics of nanosheets and their incorporation into devices receive some attention, this thesis will focus mainly on the synthetic aspects of 2D materials research.

The majority of studies examining the role of prenatal androgens on abnormal behavior have focused on developmental disorders showing large male to female ratios (i.e., autism and Tourette's Syndrome). There is a scarcity of research examining the role of prenatal sex hormones on female-linked disorders or disorders showing adult onset. This study is the first to evaluate the organizational and activational influences of sex hormones on adult levels of anxiety, while simultaneously examining previously reported hormone-behavior associations. In addition, this study explores the relation between prenatal and postnatal sex hormones and two other female-linked disorders, depression and borderline personality. As part of this study, participants (n = 110) completed a battery of psychopathology questionnaires, gender role measures, and spatial/cognitive tasks. Prenatal androgen levels were indirectly measured by means of the index to ring finger ratio (2D:4D), and testosterone and estrogen levels were obtained from saliva samples. Results replicate previously reported sex differences in anxiety and gendered behavior and confirm various hormone-behavior associations. More importantly, results provide preliminary evidence for the organizational role of prenatal androgens in two female-linked conditions, anxiety and borderline personality. Individuals with a higher (i.e., more feminine) 2D:4D reported greater symptoms of trait anxiety and borderline personality (i.e., affective instability), and this effect appeared to be strongest in males.

The majority of studies examining the role of prenatal androgens on abnormal behavior have focused on developmental disorders showing large male to female ratios (i.e., autism and Tourette's Syndrome). There is a scarcity of research examining the role of prenatal sex hormones on female-linked disorders or disorders showing adult onset. This study is the first to evaluate the organizational and activational influences of sex hormones on adult levels of anxiety, while simultaneously examining previously reported hormone-behavior associations. In addition, this study explores the relation between prenatal and postnatal sex hormones and two other female-linked disorders, depression and borderline personality. As part of this study, participants (n = 110) completed a battery of psychopathology questionnaires, gender role measures, and spatial/cognitive tasks. Prenatal androgen levels were indirectly measured by means of the index to ring finger ratio (2D:4D), and testosterone and estrogen levels were obtained from saliva samples. Results replicate previously reported sex differences in anxiety and gendered behavior and confirm various hormone-behavior associations. More importantly, results provide preliminary evidence for the organizational role of prenatal androgens in two female-linked conditions, anxiety and borderline personality. Individuals with a higher (i.e., more feminine) 2D:4D reported greater symptoms of trait anxiety and borderline personality (i.e., affective instability), and this effect appeared to be strongest in males.

Μελέτη και εξομοίωση διαφόρων τύπων ηλεκτροδίων γείωσης με το Οpera-2d / Simulation of several grounding electrode types with Opera-2d

Asymmetric simple exclusion process (ASEP) is a driven stochastic lattice model of particles that move preferentially in one direction. If particles move only in one direction, the model is known as totally asymmetric process. Conventionally, preferred direction of motion is chosen to be to the right. Particles interact through the hard core exclusion rule, meaning that no more than one particle is allowed to occupy one lattice site. In this work following ASEP models are presented. First we study square diagonal lattice with particles that occupy one lattice site and move along the square diagonals. Mean-field theory was developed for this model. The results that were obtained are the dependency of the current on density of the particles, spatial density distribution along the horizontal direction and the phase diagram of the system. Mean-field theory results were compared to simulations. Next model was lattice with extended particles, i.e. particles that occupy more than one lattice site. Unlike the first model, in this system the particle-hole symmetry is broken. Results for current flow, density distribution and phase diagrams were obtained both by mean-field theory and Monte-Carlo (MC) simulations. Another system was the lattice with vertical particle drift. Now particles that occupy one lattice site jump not only in one preferred horizontal directions but there is also one preferred vertical direction for particle flow. Both mean-field theory and simulations were studied for this system and results were compared. Also we explore the system with immovable obstacle. Obstacle is one or several particles located at fixed positions. In this model we observe increase in particle density in front of the obstacle and "shadow" behind it. It is expected that the shape and size of those formations are symmetrical in transverse direction.

No description available.

Two-dimensional (2D) materials, referring to materials being just one atom thick, prove to be attractive not only in fundamental research but also in applications. Graphene, a single layer of carbon atoms arranged in hexagonal rings, is just the first among other materials (including hexagonal boron nitride and molybdenum disulfide) that could be isolated into mono-atomic layers. The presented thesis investigates proton transport through atomically thin two-dimensional materials. While the electronic, optical and mechanical properties of graphene and other 2D materials have been intensely researched over the past decade, much less is known on the interaction of these crystals with protons. It has been reported that most of the defect free two dimensional materials are impermeable to nearly all gases, molecules and ions. Whether proton, the smallest positively charged ion, could transport through two dimensional materials at a low energy level remains unknown. This work investigates proton transport through 2D materials, including graphene, hexagonal boron nitride and molybdenum disulfide, in two different systems: Nafion/Pd solid system and liquid/liquid interface system, both of which provided consistent results. Our results suggest that proton can transport through the interatomic spacings in the lattice of single layer BN and graphene, while single layer MoS2 is impermeable to protons. Single layer BN is the most conductive to protons among the 2D materials investigated in this thesis. Lower proton conductance of graphene is due to its delocalized π electrons while proton impermeability of MoS2 is due to the three atomic layers structure. Moreover, proton transfer is greatly facilitated by the deposition of platinum nanoparticles on the proton conductive 2D membranes to such a degree that platinum decorated BN seems to present negligible resistance to the transfer of protons through its lattice.

Le sujet de cette thèse est à l’interface entre l’étude de composés à base de nitrure et des structures émergeantes formées par les matériaux bidimensionnels (2D) d’épaisseur atomique. Ce travail se consacre sur l’hybridation des propriétés électriques et optiques des semi-conducteurs à larges bandes interdites que sont les nitrures et des performances mécaniques, électriques et optiques des matériaux lamellaires, récemment isolé à l’échelle d’un plan atomique, qui sont aujourd’hui considérées avec attention aux regards de futures applications et d’études plus fondamentales. En particulier, une étude des propriétés électroniques, optiques et structurelles d’hétérostructures composées de plusieurs matériaux lamellaires et d’interfaces entre matériaux 2D et 3D a été réalisé par des moyens de microscopie et de spectroscopie tel que la spectroscopie Raman, de photoémission et d’absorption.Ce manuscrit traite dans un premier temps des propriétés structurelles et électroniques du nitrure de bore hexagonal (h-BN), matériau isolant aux propriétés optiques exotiques et essentiel dans la future intégration de ce type de matériaux 2D permettant de mettre en valeur leurs propriétés intrinsèques.En utilisant le graphène comme substrat les problèmes de mesures par photoémission rencontrés pour des matériaux isolant ont pu être surmonté dans le cas du h-BN et une étude des défauts structurels a pu être réalisée. Par conséquent, les premières mesures directes de la structure de bande électronique de plusieurs plans de h-BN sont présentées dans ce manuscrit.Dans un second temps, une approche d’intégration de ces matériaux 2D différente a été étudiée en formant une hétérostructure 2D/3D. L’interface de cette hétérojonction, composée d’un plan de disulfure de molybdène (MoS2) de dopage intrinsèque N associé à 300 nm de nitrure de gallium (GaN) intentionnellement dopé P à l’aide de magnésium, a été caractérisée. Un transfert de charge du GaN vers le MoS2 a pu être identifié suggérant un contrôle des propriétés électroniques de ce type de structure par le choix de matériaux.Ces travaux ont permis de révéler les diagrammes de bandes électroniques complet des structures étudiées a pu être obtenu permettant une meilleur compréhension de ces systèmes émergeants. / This thesis is at the interface between the study of nitride based compounds and the emerging structures formed by atomically thin bi-dimensional (2D) materials. This work consists in the study of the hybridization of the properties of large band gap materials from the nitride family and the mechanical, electronic and optical performances of layered materials, recently isolated at the monolayer level, highly considered due to their possible applications in electronics devices and fundamental research. In particular, a study of electronics and structural properties of stacked layered materials and 2D/3D interfaces have been realised with microscopic and spectroscopic means such as Raman, photoemission and absorption spectroscopy.This work is firstly focused on the structural and electronic properties of hexagonal boron nitride (h-BN), insulating layered material with exotic optical properties, essential in in the purpose of integrating these 2D materials with disclosed performances. Using graphene as an ideal substrate in order to enable the measure of insulating h-BN during photoemission experiments, a study of structural defects has been realized. Consequently, the first direct observation of multilayer h-BN band structure is presented in this manuscript. On the other hand, a different approach consisting on integrating bi-dimensional materials directly on functional bulk materials has been studied. This 2D/3D heterostructure composed of naturally N-doped molybdenum disulphide and intentionally P-doped gallium nitride using magnesium has been characterised. A charge transfer from GaN to MoS2 has been observed suggesting a fine-tuning of the electronic properties of such structure by the choice of materials.In this work present the full band alignment diagrams of the studied structure allowing a better understanding of these emerging systems.

Orientador: Pedro de Magalhães Padilha / Resumo: Este trabalho apresenta os resultados de proteínas associadas ao mercúrio em amostras de tecido muscular e hepático de pirarucu (Arapaima gigas) e piranha preta (Serrasalmus rhombeus) oriundos do complexo hidrelétrico de Jirau, na Bacia do Rio Madeira, região amazônica do Brasil. O proteôma do músculo e fígado dessas espécies foi obtido por eletroforese bidimensional em gel de poliacrilamida (2D PAGE). O mercúrio presente nos spots proteicos foi determinado por espectrometria de absorção atômica em forno de grafite (GFAAS) após mineralização ácida assistida por banho de ultrassom. Os spots proteicos que apresentaram mercúrio foram caracterizados por espectrometria de massas por ionização com eletrospray em sequência (ESI- MS/MS) após digestão tríptica. As determinações GFAAS indicaram que a maior parte do mercúrio está ligada a fração proteica com massa molar (Mm) inferior a 90 kDa. As concentrações de mercúrio nos spots apresentaram-se na faixa de 4,07 – 164,63 µg g-1 no tecido muscular de pirarucu; 0,86 – 25,34 µg g-1 no tecido hepático de pirarucu; 7,67 – 156,18 µg g-1 no tecido muscular de piranha preta e 2,17 – 31,42 µg g-1 no tecido hepático de piranha preta. A análise por ESI-MS/MS permitiu caracterizar em dezenove spots proteicos as seguintes proteínas e/ou enzimas: Triosephosphate isomerase, Fructose-bisphosphate aldolase, Ckmb protein,, Cofilin 2 (Muscle), Actin_ alpha_ cardiac muscle 1a, Actin_ alpha 1_ skeletal muscle, Novel protein similar to zebrafish hemoglobin... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor