Dissertations / Theses on the topic 'Functional applications'

Aromatic and aliphatic diacid chlorides were used to condense naturally occurring diamino acids and their esterified derivatives. It was anticipated the resulting functional polyamides would biodegrade to physiologically acceptable compounds and show pH dependant solubility could be used for biomedical applications ranging from enteric coatings to hydrosoluble drug delivery vehicles capable of targeting areas of low physiological pH. With these applications in mind the polymers were characterised by infra red spectroscopy, gel permeation chromatography and in the case of aqueous soluble polymers by potentiometric titration. Thin films of poly (lysine ethyl ester isophthalamide) plasticised with poly (caprolactone) were cast from DMSO/chloroform solutions and their mechanical properties measured on a Hounsfield Hti tensiometer. Interfacial synthesis was investigated as a synthetic route for the production of linear functional polyamides. High molecular weight polymer was obtained only when esterified diamino acids were condensed with aromatic diacid chlorides. The method was unsuitable for the production of copolymers of free and esterified amino acids with a diacid chloride. A novel miscible mixed solvent single phase reaction was investigated for production of copolymers of esterified and non-esterified amino acids with diacid chlorides. Aliphatic diacid chlorides were unsuitable for condensing diamino acids using this technique because of high rates of hydrolysis. The technique gave high molecular weight homopolymers from esterified diamino acids and aromatic diacid chlorides.

Ce projet s’est focalisé sur l’ajout de nouvelles propriétés à des papiers grâce à l’utilisation de nanocelluloses fonctionnelles. Ces nanocelluloses sont des nanoparticules extraites du bois qui peuvent être divisées en deux catégories : les nanofibrilles de cellulose (CNFs) et les nanocristaux de cellulose (CNCs). Ce travail s’est essentiellement penché sur l’utilisation des CNFs. Leur réactivité chimique a été utilisée afin de les fonctionnaliser avec des organotrialkoxysilanes. C’est aussi leur fort enchevêtrement ainsi que la grande viscosité de ces CNFs en suspension qui ont été utilisés afin de synthétiser des petites particules de silsesquioxane pour rendre le matériau final antimicrobien et (super)hydrophobe. Les connaissances obtenues à travers l’étude sur des films modèle de CNFs ont ensuite été appliquées au couchage du papier. Ces CNFs fonctionnelles ont donc été évaluées pour le développement d’un papier possédant une surface antimicrobienne, anti-adhérente, barrière aux graisses ou superhydrophobe
The aim of this work is to implement new properties to a paper based material via the use of functional nanocelluloses. Nanocelluloses are nanoparticles extracted from wood and distinguished in two categories: Cellulose Nanofibrils (CNFs) and Cellulose Nanocrystals (CNCs). This work has only been carried out with CNFs. The chemical reactivity of CNFs was used to functionalize them with organotrialkoxysilanes. The entangled network and highly viscous suspension of CNFs was also used to synthesize silsesquioxane particles with limited size to impart (super)hydrophobic and antimicrobial properties. Knowledge obtained through the study of model CNFs films was then applied to paper based material coating. The functional CNFs were evaluated for its use in an antimicrobial, anti-adherent, greaseproof or superhydrophobic paper surface

Les nanoparticules fonctionnalisées continuent de susciter beaucoup d’interêt dans les applications biomédicales et les essais biologiques. Elles sont devenues un élément clé dans la recherche en nanobiotechnologie. Un des axes primordiaux des travaux de recherche est le développement de stratégies polyvalentes de fonctionnalisation de surface pour différentes nanoparticules allant de nanostructures de diamants à des nanoparticules d'oxyde de fer, des particules de silice et des nanocapsules lipidiques. Un des objectifs en particulier a été l’introduction de diverses fonctionnalisations sur les mêmes nanoparticules en utilisant soit des ligands dérivés de la dopamine ou soit par chimie « click » de Cu(I) catalysé. Il en résulte des nanostructures bien dispersées fonctionnalisées avec différents ligands à leurs surfaces. Les applications de ces nanostructures pour l'inhibition des infections virales et pour la délivrance de gènes ont été étudiées. En effet, l'inhibition de l'entrée du VHC a été identifiée comme étant une stratégie thérapeutique potentielle. Il a pu être démontré que différentes nanoparticules peuvent être efficacement conçues pour afficher les propriétés de lectine et se comporter donc comme des inhibiteurs efficaces d'entrée du virus in vitro. Les pseudo-lectines étudiées ici comprennent les nanoparticules dérivées du fer, de silice, du diamant et des nanocapsules lipidiques comportant toutes des fragments d’acide boronique attachés à leurs surfaces.Par ailleurs, le potentiel des nanoparticules de diamant pour la délivrance de gènes a été étudié
Functionalized nanoparticles continue to attract interest in biomedical applications and bioassays and have become a key focus in nanobiotechnology research. One of the primal focuses of the research work was the development of versatile surface functionalization strategies for different nanoparticles ranging from diamond nanostructures to iron oxide nanoparticles, silica particles and lipid nanocapsules. One particular aim was the introduction of various functionalities onto the same nanoparticles using either dopamine-derived ligands or Cu(I) catalyzed “click” chemistry strategies. This resulted in well-dispersed nanostructures with different ligands present on the surface of the nanostructures. The possibilities to use such nanostructures for the inhibition of viral infections and for gene delivery were investigated. Indeed, inhibiting the entry of HCV has been identified as a potential therapeutic strategy. It could be demonstrated that various nanoparticles can be efficiently engineered to display “lectin-like” properties and indeed behave as effective viral entry inhibitors, in vitro. The pseudo-lectins investigated here include iron-, silica-, diamond-, (lipid nanocapsule)-derived nanoparticles all featuring surface-attached boronic acid moieties. In parallel to work on HCV entry inhibition, the potential of diamond nanoparticles as gene delivery system was investigated. Water dispersible and biocompatible polypegylated diamond particles were prepared using different dopamine ligands and their effect on gene delivery has been studied

Cette thèse décrit le développement de nouvelles méthodes pour obtenir des nanoparticules fonctionnelles polyvalentes qui peuvent potentiellement être utilisées pour des applications biomédicales telles que la vectorisation de médicaments, des essais biologiques et la bio-imagerie. Les nanomatériaux sont des outils polyvalents qui ont trouvé des applications comme vecteurs de médicaments, la bio-imagerie ou les biocapteurs. En particulier, les nanoparticules de type core-shell ont attiré beaucoup d'attention en raison de leur petite taille, une relation surface/volume élevée, et une biocompatibilité. Dans ce contexte, nous proposons dans la première partie de la thèse (Chapitre 2), une nouvelle méthode pour obtenir des nanoparticules core-shell via la polymérisation radicalaire en émulsion et vivante combinées. Des particules cœurs de polystyrène de 30 à 40 nm, avec une distribution de taille étroite et portant à la surface des groupements iniferter ont été utilisés pour amorcer la polymérisation supplémentaire d'une couche de polymère. Des nanoparticules core-shell ont été préparées de cette façon. Différents types d’enveloppes : anionique, zwitterioniques, à empreintes moléculaires, thermosensibles, ont ainsi été greffées. Notre méthode est une plate-forme polyvalente permettant d'ajouter des fonctionnalités multiples soit dans le noyau et/ou l'enveloppe pour les études d'interaction cellulaire et de toxicité, ainsi que des matériaux récepteurs pour l'imagerie cellulaire. Dans la deuxième partie de la thèse (Chapitre 3), nous décrivons un procédé nouveau et polyvalent pour la modification de surface des nanoparticules de conversion ascendante (UCP). Ce sont des nanocristaux fluorescents dopés de lanthanides qui ont récemment attiré beaucoup d'attention. Leur fluorescence est excitée dans le proche infrarouge, ce qui les rend idéales comme marqueurs dans des applications biomédicales telles que les tests biologiques et la bio-imagerie, l'auto-fluorescence étant réduite par rapport à des colorants organiques et les quantum dots. Cependant, les UCP sont hydrophobes et non-compatible avec les milieux aqueux, donc une modification de leur surface est essentielle. La stratégie que nous proposons utilise l'émission UV ou visible après excitation en proche infrarouge des UCP, comme source de lumière secondaire pour la photopolymérisation localisée de couches minces hydrophiles autour les UCP. Notre méthode offre de grands avantages comme la facilité d'application et la fonctionnalisation de surface rapide pour fixer divers ligands, et fournit une plateforme pour préparer des UCP encapsulée de polymères pour des différentes applications. Des hydrogels stimuli-sensibles sont des matériaux qui changent leurs propriétés physicochimiques en réponse à des stimuli externes tels que la température, le pH ou la lumière. Ces matériaux intelligents jouent un rôle critique dans des applications biomédicales telles que la vectorisation de médicaments ou l'ingénierie tissulaire. La troisième partie de cette thèse (Chapitre 4) propose un nouveau procédé de préparation d'hydrogels photo et pH sensible. Deux composantes, l'un photosensible à base dl'acide 4-[(4-méthacryloyloxy) phénylazo] benzoïque et l'autre cationic contenant des unités 2-(diéthylamino)éthyl méthacrylate, ont été synthétisés. Leur association donne des particules monodispersées de 100 nm photo et pH sensibles. Ces nanoparticules peuvent être potentiellement utilisées pour la vectorisation de médicaments, en particulier de biomolécules telles que protéines ou siARN. En conclusion, nous avons conçu plusieurs nouvelles méthodes efficaces, polyvalentes, génériques et facilement applicables pour obtenir des nanoparticules et nanocomposites de polymères fonctionnels qui peuvent être appliqués dans de différents domaines biomédicaux comme la vectorisation de médicaments, les biocapteurs, les tests biologiques et la bio-imagerie
This thesis describes the development of novel methods to obtain versatile, functional nanoparticles that can potentially be used for biomedical applications such as drug delivery, bioassays and bioimaging. Nanomaterials are versatile tools that have found applications as drug carriers, bioimaging or biosensing. In particular, core-shell type nanoparticles have attracted much attention due to their small size, high surface to volume ratio and biocompatibility. In this regard, we propose in the first part of the thesis (Chapter 2), a novel method to obtain core-shell nanoparticles via combined radical emulsion and living polymerizations. Polystyrene core seeds of 30-40 nm, with a narrow size distribution and surface-bound iniferter moieties were used to further initiate polymerization of a polymer shell. Core-shell nanoparticles were prepared in this way. Different types of shells : anionic, zwitterionic, thermoresponsive or molecularly imprinted shells, were thus grafted. Our method is a versatile platform with the ability to add multi-functionalities in either the core for optical sensing or/and the shell for cell interaction and toxicity studies, as well as receptor materials for cell imaging. In the second part of the thesis (Chapter 3), we describe a novel and versatile method for surface modification of upconverting nanoparticles (UCPs). UCPs are lanthanide-doped fluorescent nanocrystals that have recently attracted much attention. Their fluorescence is excitated in the near infrared, which makes them ideal as labels in biomedical applications such as bioimaging and bioassays, since the autofluorescence background is minimized compared to organic dyes and quantum dots. However, UCPs are hydrophobic and non-compatible with aqueous media, therefore prior surface modification is essential. The strategy that we propose makes use oft he UV or Vis emission light of near-infrared photoexcited upconverting nanoparticles, as secondary light source for the localized photopolymerization of thin hydrophilic shells around the UCPs. Our method offers great advantages like ease of application and rapid surface functionalization for attaching various ligands and therefore can provide a platform to prepare polymeric-encapsulated UCPs for applications in bioassays, optical imaging and drug delivery. Stimuli responsive hydrogels are materials that can change their physico-chemical properties in response to external stimuli such as temperature, pH or light. These smart materials play critical roles in biomedical applications such as drug delivery or tissue engineering. The third part of the thesis (Chapter 4) proposes a novel method for obtaining photo and pH-responsive supramolecularly crosslinked hydrogels. Two building blocks, one containing photoresponsive 4-[(4-methacryloyloxy)phenylazo] benzoic acid and the other, consisting of cationic 2-(diethylamino)ethyl methacrylate units, were first synthesized. Combining the two building blocks yielded photo and pH responsive monodisperse 100-nm particles. These nanoparticles can be eventually utilized for drug delivery, especially delivery of biomolecules such as siRNAs or proteins. In conclusion, we have designed several new efficient, versatile, generic and easily applicable methods to obtain functionalized polymer nanoparticles and nanocomposites that can be applied in various biomedical domains like drug delivery, biosensing, bioassays and bioimaging

In this thesis we will address the study of quantum field theories using the exact renormalization group technique. In particular, we will calculate the flow of a Yukawa system coupled to gravity and that of a higher derivative nonlinear sigma model. The study of the Yukawa system in presence of gravity, as well as the study of any matter theory coupled to gravity, is important for two reason. First, it is interesting to see what gravitational dressing one should expect to the beta functions of any matter theory. Second, it is important to test the possibility that gravity is an asymptotically safe theory [1, 2] against the addition of matter degrees of freedom. We also calculate the 1-loop flow of a general higher derivative nonlinear sigma model, using exact renormalization group techniques. We think that the nonlinear sigma model is an important arena to test the exact renormalization. The reason is that the nonlinear sigma model shares many of the features of gravity, like perturbative nonrenormalizability, but does not have the additional complication of a local gauge invariance. Furthermore, it is an interesting question whether a nonlinear sigma model admits a ultraviolet limit or it has to be regarded as an effective field theory only. The plan of the work is as follows. In Chapter 1 we give a very brief introduction to the technique of functional exact renormalization group. In Chapter 2 we introduce the notion of “Asymptotic Safety” [1] and discuss some of the approximation schemes generally involved in calculations. In Chapter 3 we use a simple Yukawa model as a toy model for many of the techniques we will need later. We also discuss the background field method in the context of a theory with local gauge invariance, which will turn out to be useful in Chapter 4. In Chapter 4 we couple the simple Yukawa model with gravity and calculate its renormalization group flow. In Chapter 5 we study numerically the flow calculated in Chapter 4 and point out the possibility that the model admits a nontrivial ultraviolet limit. Chapter 6 is the final chapter and contains the study of the flow of the higher derivative nonlinear sigma model; it is a self contained chapter. In fact, Chapter 5 and 6 contain separate discussions for the results of the Yukawa and sigma model, respectively. We dedicate the appendices to arguments that would have implied very long digressions in the main text.

The general truth that the principle of causality, that is, the future state of a system is independent of its past history, cannot support all the cases under consideration, leads to the introduction of the FDEs. However, the strong need of modelling real life problems, demands the inclusion of stochasticity. Thus, the appearance of the SFDEs (special case of which is the SDDEs) is necessary and definitely unavoidable. It has been almost a century since Langevin's model that the researchers incorporate noise terms into their work. Two of the main research interests are linked with the existence and uniqueness of the solution of the pertinent SFDE/SDDE which describes the problem under consideration, and the qualitative behaviour of the solution. This thesis, explores the SFDEs and their applications. According to the scientific literature, Ito's work (1940) contributed fundamentally into the formulation and study of the SFDEs. Khasminskii (1969), introduced a powerful test for SDEs to have non-explosion solutions without the satisfaction of the linear growth condition. Mao (2002), extended the idea so as to approach the SDDEs. However, Mao's test cannot be applied in specific types of SDDEs. Through our research work we establish an even more general Khasminskii-type test for SDDEs which covers a wide class of highly non-linear SDDEs. Following the proof of the non-explosion of the pertinent solution, we focus onto studying its qualitative behaviour by computing some moment and almost sure asymptotic estimations. In an attempt to apply and extend our theoretical results into real life problems we devote a big part of our research work into studying two very interesting problems that arise : from the area of the population dynamks and from·a problem related to the physical phenomenon of ENSO (EI Nino - Southern Oscillation)

Biomedical devices are commonly used in all areas of healthcare, These devices, which range from contact lenses through to endotracheal tubes, are most often fashioned from materials which allow the device to carry out its function thoroughly, but in doing so render the device susceptible to a number of complications. Two of the most major complications are that of device infection and poor frictional behaviour at the interface of the device and human tissue. This thesis details the development and characterisation of various polymeric systems which allow the resolution of these problems. With regard to infection, well established photodynamic techniques are further developed to provide a system which can bring about effective prevention of infection for prolonged durations of time, leading to a wide range of advantages, potentiating the function of the device. Biomaterial frictional behaviour is improved in a number of ways, including the development of next generation device coatings which are more easily wetted, offer improved biocompatibility, and also offer an improved tenacity of effect. Moreover, further work in this thesis has led to the development of successful photochemical attachment pathways for the addition of such coatings to the surface of commonly used biomaterial substrates.

The study of conformal symmetry is motivated through an example in statistical mechanics and then rigorously developed in quantum field theories in general spatial dimensions. In particular, primary fields are introduced as the fundamental objects of such theories and then studied in the formalism of radial quantization. The implications of conformal invariance on the functional form of correlation functions are studied in detail. Conformal blocks are defined and various approaches to their analytical and numerical calculation are presented with a special emphasis on the one-dimensional case. Building on these preliminaries, a modern formulation of the conformal bootstrap program and its various extensions are discussed. Examples are given in which bounds on the scaling dimensions in a one-dimensional theory are derived numerically. Using these results I motivate the technique of using the extremal functional bootstrap which I then develop in more detail. Many technical details are discussed and examples shown. After a brief discussion of conformal field theories with a boundary I apply numerical methods to find constraints on the spectrum of the 3D Ising model. Another application is presented in which I study the 4-point function on the boundary of a particular theory in Anti-de-Sitter space in order to approximate the mass spectrum of the theory.
O estudo da simetria conforme é motivado através de um exemplo em mecânica estatística e em seguida rigorosamente desenvolvido em teorias de campos quânticos em dimensões espaciais gerais. Em particular, os campos primários são introduzidos como os objetos fundamentais de tais teorias e então estudados através do formalismo de quantização radial. As implicações da invariância conforme na forma funcional das funções de correlação são estudadas em detalhe. Blocos conformes são definidos e várias abordagens para seu cálculo analítico e numérico são apresentadas com uma ênfase especial no caso unidimensional. Com base nessas preliminares, uma formulação moderna do programa de bootstrap conforme e suas várias extensões são discutidas. Exemplos são dados em que limites nas dimensões de escala em uma teoria unidimensional são derivados numericamente. Usando esses resultados, motivei a técnica de usar o bootstrap funcional extremo, que depois desenvolvo em mais detalhes. Diversos detalhes técnicos são discutidos e exemplos são apresentados. Após uma breve discussão das teorias de campo conformes com fronteiras, eu aplico métodos numéricos para encontrar restrições no espectro do modelo de Ising em 3D. Outra aplicação é apresentada em que eu estudo a função de 4 pontos na fronteira de uma teoria particular no espaço Anti-de-Sitter, a fim de aproximar o espectro de massa da teoria.

Cette thèse décrit l'étude de différentes méthodologies qui ont été utilisées pour contrôler l'assemblage de trois systèmes moléculaires sur des surfaces, afin de former des structures supramoléculaire hautement ordonnées à l'échelle nanoscopique et microscopique. Les structures de couches minces ont été préliminairement étudiées par microscopie à force atomique (AFM) à l'interface solide-air. La première partie de la thèse porte sur la technique de préparation de couches minces Langmuir-Blodgett (LB). Cette technique permet d'obtenir une croissance latérale de monocouche orientée sur un substrat de mica et ce, à partir de molécules amphiphiles possédant une queue hydrophobe simple ou double. Des monocouches ordonnées ont été réalisées suivant deux méthodes différentes. La première méthode consiste à exploiter le phénomène d'instabilité lié au transfert de molécules sur des substrats dans le procédé Langmuir-Blodgett (LB), ce qui permet de générer des canaux périodiques de taille nanométrique dans le cas de monocouche de dimyristoyl-phosphatidylcholine (DMPC) transférée sur un substrat de mica. La seconde méthode utilisée consiste à utiliser des molécules amphiphiles possédant de grosses têtes amphiphiles interagissant fortement entre elles. L'utilisation des molécules de palmitate de quercetine (QP) ont permis l'obtention de structures supramoléculaires de type fibre et ceci dans des domaines micrométriques. Les images AFM (mode tapping) de films mixtes montrent que les fibres adoptent une conformation courbée conduisant à de nouveaux types de domaines en forme de spirale. Les résultats obtenus ouvrent de nouvelles perspectives pour l'utilisation de films LB comme outil permettant d'organiser des monocouches a plusieurs composants avec un haut degré de précision. La seconde partie de la thèse est consacrée à l'autoassemblage, sur des surfaces, d'une nouvelle classe de système macromoléculaire, des polyrotaxanes conjugués entoures par des cyclodextrines, dans le but d'optimiser les performances des LEDs basés sur ces architectures complexes. En particulier la morphologie de surface des mélanges de poly(4,4'-diphenylenevinylene) PDV, soluble dans l'eau, et de leur forme " rotaxane " -CD-PDV, avec du poly(ethylene oxyde) PEO, déposés par spin coating a été étudié par AFM en mode tapping. Cette dernière technique a permis de révéler l'existence d'un processus de reconnaissance interfacial. Ce phénomène a été mis en évidence par l'absence de ségrégation de phase ainsi que par l'ordre structural induit par le choix du substrat. Ceci démontre la bonne miscibilité des deux constituants hydrophiles, comme le confirment les mesures de luminescence des films et des dispositifs intégrant ces systèmes. Par ailleurs, des analyses AFM effectuées sur films d' epousseur " submonolayer " de polyrotaxane à base de poly-para-phenylene (-CD-PPP) seul ou mélangé avec du PEO, démontre que l'interaction entre les deux composants a lieu à l'échelle moléculaire. Au contraire, pour les mélanges de PEO avec des polymères conjugués solubles dans des solvants organique, comme le poly(9,9'-dioctylfluorene-alt-benzothiadiazole) F8BT ou des CD-polyrotaxanes à base de polyfluorene alkylé, on observe des structures de surface qui indique des séparations de phases. La dernière partie de la thèse traite de la création de nanojunctions d'hybrides organométalliques, qui sont les composants de base pour de futures applications dans le domaine de la nanoélectronique. Ce qui nécessite à la fois la synthèse de structures moléculaires auto assemblées (approche bottom-up) et la fabrication de nanogaps métalliques par des méthodes de lithographie (top-down). L'auto assemblage d'un gélifiant de faible poids moléculaire, le cyclohexane trisamide, en structure colonnaire via des liaisons hydrogènes a été étudié sur des films préparés par drop casting. Le but de cette étude était d'utiliser un champ électrique (DC) pour orienter les fibres entres deux nanoélectrodes. Le champ électrique a été appliqué entre deux électrodes en or fabriquées sur un wafer de silicone à l'aide d'un faisceau d'ions focalisé (FIB). Bien que les fibres tendent à former des superstructures, une faible proportion de ces architectures s'oriente convenablement lors de l'application du champ électrique. Les résultats décrit dans cette thèse montrent qu'il est important de pouvoir contrôler des interactions intramoléculaires ainsi qu'intermoléculaire, sans oublier les interactions spécifique au surfaces afin de pouvoir piloter l'autoassemblage sur des surfaces solides et ainsi créer des architectures nanométriques pré-programmées ayant des fonctions bien définies. De plus, il a été démontré qu'une approche supramoléculaire représente une voie possible vers la fabrication de prototypes de dispositifs pour l'électronique moléculaire avec des performances améliores
In this thesis different methodologies have been used to drive the assembly at surfaces of three different (macro)molecular systems towards highly ordered supramolecular nanoscopic and microscopic structures. The structures of the thin films have been studied at the solid-air interface making use primarily of Scanning Force Microscopy (SFM). The first part of the thesis was focused on the use of the Langmuir-Blodgett (LB) technique to grow laterally ordered monolayers on mica from amphiphilic molecules having either a double or a single hydrophobic tail. Ordered monolayers were produced using two different strategies. The former exploits instability phenomena connected to the LB transfer and allows the generation of periodic nanometric channels, in dimyristoyl-phosphatidylcholine (DMPC) monolayers transferred to mica. The latter strategy consists of assembling amphiphiles having large and strongly mutually interacting heads. In this case, quercetin palmitate (QP) molecules were used to build up micrometric domains of supramolecular fiber-like structures. In the mixed films, the nanoscopic fibers were observed by tapping mode SFM to adopt a curved conformation and wrap up, leading to novel spiral-like domains. The results obtained open new perspectives to the use of LB as a tool for nanopatterning (multicomponents) monolayers with a high degree of precision. The second part of the thesis was devoted to self-assembly at surfaces of a new class of supramolecular system, based on cyclodextrin-threaded conjugated polyrotaxanes, with the final aim of optimizing the performance of LEDs based on these complex architectures. In particular the surface morphology of blends of water soluble poly(4,4'-diphenylenevinylene), PDV and of the correspondent rotaxinated form -CD-PDV, with poly(ethylene oxide), PEO, grown by spin-coating was explored by non-contact SFM. The SFM analysis revealed the occurrence of an interfacial recognition process, which is evidenced by a structural order induced by the chosen substrate, and the absence of phase segregation. This provides evidence for a good miscibility of the two hydrophilic components, as supported by luminescence data from films and devices constituted by those systems. This was also proved by the SFM analysis on sub-monolayer thick films of poly-para-phenylene based polyrotaxane (-CD-PPP) naked and blended with PEO, highlighting the interaction between the two components at single molecule level. Significant surface structures, indicative of phase separations, were instead observed when blending PEO with organic-solvent soluble conjugated polymers, such as poly(9,9'-dioctylfluorene-alt-benzothiadiazole) F8BT, and alkylated polyfluorene based CD-polyrotaxanes. The third part was addressed to the tailoring of hybrid organic-metallic nanojunctions, which are key components for future applications in the field of nanoelectronics. This required the combination of the self-assembly of molecular structures (bottom-up approach) with micro- and nano-fabrication for the production of metallic nanogaps with lithographic methods (top-down). The self-assembly behavior of a low molecular weight gelators, cyclohexane trisamide which self-associate into columnar structures through hydrogen bonding, was studied on films prepared by drop-casting. The goal was to use a DC electric field to place the well-defined ordered supramolecular arrangement in between two facing Au nanoelectrodes, supported on a silicon wafer, nanofabricated by means of Focused Ion Beam. Although the fibers tend to intercoil into super-structures, a weak propensity of these architectures to orient as a consequence of the applied electric field was found. The results described in this thesis reveal that it is of prime importance to achieve a full control over the interplay of intra-molecular as well as inter-molecular and interfacial interactions in order to drive the nanoconstruction at solid surfaces towards pre-programmed architectures with given properties. Moreover it is demonstrated that the supramolecular approach represents a successful route to fabricate prototype of molecular electronics devices with improved performance

Carbon nanomaterials are an active frontier of research in current nanotechnology. Single wall Carbon Nanotube (SWNT) is a unique material which has already found several applications in photonics, electronics, sensors and drug delivery. This thesis presents a summary of the author’s research on functionalisation of SWNTs, a study of their optical properties, and potential for an application in laser physics. The first significant result is a breakthrough in controlling the size of SWNT bundles by varying the salt concentrations in N-methyl 2-pyrrolidone (NMP) through a salting out effect. The addition of Sodium iodide leads to self-assembly of CNTs into recognizable bundles. Furthermore, a stable dispersion can be made via addition polyvinylpyrrolidone (PVP) polymer to SWNTs-NMP dispersion, which indicates a promising direction for SWNT bundle engineering in organic solvents. The second set of experiments are concerned with enhancement of photoluminescence (PL), through the formation of novel macromolecular complexes of SWNTs with polymethine dyes with emission from enhanced nanotubes in the range of dye excitation. The effect appears to originate from exciton energy transfer within the solution. Thirdly, SWNT base-saturable absorbers (SA) were developed and applied to mode locking of fibre lasers. SWNT-based SAs were applied in both composite and liquid dispersion forms and achieved stable ultrashort generation at 1000nm, 1550nm, and 1800 nm for Ytterbium, Erbium and Thulium-doped fibre laser respectively. The work presented here demonstrates several innovative approaches for development of rapid functionalised SWNT-based dispersions and composites with potential for application in various photonic devices at low cost.

Nanostructuring functional materials can lead to a variety of enhanced intrinsic material properties. In particular, nanowires (NWs) have large surface-to-volume ratio and large aspect ratio (length / diameter), which makes them sensitive to low-amplitude vibrations and have increased flexibility compared to the bulk form of the material. In this thesis, piezoelectric, ferroelectric, ferromagnetic and magnetoelectric (ME) NWs have been explored in the context of vibrational energy harvesting and magnetic energy harvesting and sensing; because of their increased piezoelectric coefficients and ME coupling compared to bulk. Low-temperature, solution-processable and hence scalable fabrication techniques have been used throughout this work. Electrochemical deposition or electrodeposition (ED) in conjunction with nanoporous templates i.e. template-assisted electrodeposition (TAED) have been used to grow piezoelectric zinc oxide (ZnO) and ferromagnetic nickel (Ni) NWs and three template-wetting based techniques have been used to grow ferroelectric poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) NWs and nanotubes (NTs). Both techniques have been optimised and subsequently combined to synthesise core-shell or (1-1) Ni - P(VDF-TrFE) composite NWs. The structural and crystalline properties of each type of nanostructure has been studied using a variety of techniques including: scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM) and all of the NWs have been shown to be polycrystalline. The energy harvesting performance of vertically aligned ZnO NW arrays embedded in flexible, polycarbonate (PC) templates when incorporated into a flexible nanocomposite nanogenerator (NG), has been tested via periodic impacting and flexing of the NG at different frequencies. The voltage ($V$), current ($I$) and power were recorded during testing and measured across a range of external load resistances. The aligned nature of the embedded NWs ensures good piezoelectric performance across the entire device under impacting, while the PC template ensures mechanical stability and longevity of the device, confirmed by good fatigue performance over 24 hours of continuous testing, which is rarely studied in this field. The power density ($P_\mathrm{d}$) was found to be 151 mW m$^{-3}$ for low-amplitude (0.68 mm) and low-frequency (5 Hz) impacting, resulting in energy conversion efficiencies ($\chi$) and device efficiencies ($\chi$') of $\approx$ 4.2 \% and $\approx$ 3.76 x 10$^{-3}$ \% respectively. The nanoscale or surface piezoelectric charge coefficient ($d_{33}$) was measured to be $\approx$ 12.5 pm V$^{-1}$ on an individual ZnO NW, using a combination of Kelvin probe force microscopy (KPFM) and non--destructive piezoresponse force microscopy (ND-PFM). Both nanoscale and bulk ME measurements have been performed on Ni - P(VDF-TrFE) ME composite (1-1) NWs, nanocomposite (1-3) films and (2-2) laminates. The latter two structures have been fabricated using TAED and ED for the Ni NW and film respectively, in combination with drop-casting and spin-coating for the P(VDF-TrFE) films. The scanning probe microscopy (SPM) measurements used here include atomic force microscopy (AFM), KPFM, magnetic force microscopy (MFM) and piezoresponse force microscopy (PFM) and it has been found that the ME coupling in the (1-1) composites NWs is enhanced compared to the other structures, confirmed by approximating the converse ME coupling coefficient ($\alpha^\mathrm{C}$) of each composite. Additionally, vibrating sample magnetometry (VSM) has been used to confirm the ferromagnetic nature of the Ni phases in the composite structures. ME composite devices based on (2-2) and (1-3) composite materials and have been fabricated and preliminary bulk ME measurements of the ME coupling coefficient ($\alpha^\mathrm{E}$) plus energy harvesting measurements have also been performed as a proof of concept that the nanoscale ME coupling translates to the bulk, to some extent.

Functional decomposition aims at finding efficient representations for Boolean functions. It is used in many applications, including multi-level logic synthesis, formal verification, and testing. This dissertation presents novel heuristic algorithms for functional decomposition. These algorithms take advantage of suitable representations of the Boolean functions in order to be efficient. The first two algorithms compute simple-disjoint and disjoint-support decompositions. They are based on representing the target function by a Reduced Ordered Binary Decision Diagram (BDD). Unlike other BDD-based algorithms, the presented ones can deal with larger target functions and produce more decompositions without requiring expensive manipulations of the representation, particularly BDD reordering. The third algorithm also finds disjoint-support decompositions, but it is based on a technique which integrates circuit graph analysis and BDD-based decomposition. The combination of the two approaches results in an algorithm which is more robust than a purely BDD-based one, and that improves both the quality of the results and the running time. The fourth algorithm uses circuit graph analysis to obtain non-disjoint decompositions. We show that the problem of computing non-disjoint decompositions can be reduced to the problem of computing multiple-vertex dominators. We also prove that multiple-vertex dominators can be found in polynomial time. This result is important because there is no known polynomial time algorithm for computing all non-disjoint decompositions of a Boolean function. The fifth algorithm provides an efficient means to decompose a function at the circuit graph level, by using information derived from a BDD representation. This is done without the expensive circuit re-synthesis normally associated with BDD-based decomposition approaches. Finally we present two publications that resulted from the many detours we have taken along the winding path of our research.
QC 20100909

The technique of functional magnetic resonance imaging is rapidly moving from one of technical interest to wide clinical application. However, there are a number of questions regarding the method that need resolution. Some of these are investigated in this thesis. High resolutionf MRI is demonstrated at 3.0 T, using an interleaved echo planar imaging technique to keep image distortion low. The optimum echo time to use in fMRI experiments is investigated using a multiple gradient echo sequence to obtain six images, each with a different echo time, from a single free induction decay. The same data are used to construct T2* maps during functional stimulation. Various techniques for correcting the N/2 ghost are tested for use in fMRI experiments, and a method for removing the image artefact caused by external r. f. interference in a non-linearly sampled matrix is presented. The steps in the analysis of fMRI data are detailed, and two new non-directed analysis techniques, particularly for data from single events, as opposed to epoch based paradigms, are proposed. The theory behind software that has been written for fMRI data analysis is also given. Finally, some of the results from an fMRI study into the initiation of movement are presented, illustrating the power of single event experiments in the separation of cognitive processes.

Functional decomposition aims at finding efficient representations for Boolean functions. It is used in many applications, including multi-level logic synthesis, formal verification, and testing. This dissertation presents novel heuristic algorithms for functional decomposition. These algorithms take advantage of suitable representations of the Boolean functions in order to be efficient. The first two algorithms compute simple-disjoint and disjoint-support decompositions. They are based on representing the target function by a Reduced Ordered Binary Decision Diagram (BDD). Unlike other BDD-based algorithms, the presented ones can deal with larger target functions and produce more decompositions without requiring expensive manipulations of the representation, particularly BDD reordering. The third algorithm also finds disjoint-support decompositions, but it is based on a technique which integrates circuit graph analysis and BDD-based decomposition. The combination of the two approaches results in an algorithm which is more robust than a purely BDD-based one, and that improves both the quality of the results and the running time. The fourth algorithm uses circuit graph analysis to obtain non-disjoint decompositions. We show that the problem of computing non-disjoint decompositions can be reduced to the problem of computing multiple-vertex dominators. We also prove that multiple-vertex dominators can be found in polynomial time. This result is important because there is no known polynomial time algorithm for computing all non-disjoint decompositions of a Boolean function. The fifth algorithm provides an efficient means to decompose a function at the circuit graph level, by using information derived from a BDD representation. This is done without the expensive circuit re-synthesis normally associated with BDD-based decomposition approaches. Finally we present two publications that resulted from the many detours we have taken along the winding path of our research.

An vielen verschiedenen Stellen der angewandten Statistik sind die zu untersuchenden Objekte abhängig von stetigen Parametern. Typische Beispiele in Finanzmarktapplikationen sind implizierte Volatilitäten, risikoneutrale Dichten oder Zinskurven. Aufgrund der Marktkonventionen sowie weiteren technisch bedingten Gründen sind diese Objekte nur an diskreten Punkten, wie zum Beispiel an Ausübungspreise und Maturitäten, für die ein Geschäft in einem bestimmten Zeitraum abgeschlossen wurde, beobachtbar. Ein funktionaler Datensatz ist dann vorhanden, wenn diese Funktionen für verschiedene Zeitpunkte (z.B. Tage) oder verschiedene zugrundeliegende Aktiva gesammelt werden. Das erste Thema, das in dieser Dissertation betrachtet wird, behandelt die nichtparametrischen Methoden der Schätzung dieser Objekte (wie z.B. implizierte Volatilitäten) aus den beobachteten Daten. Neben den bekannten Glättungsmethoden wird eine Prozedur für die Glättung der implizierten Volatilitäten vorgeschlagen, die auf einer Kombination von nichtparametrischer Glättung und den Ergebnissen der arbitragefreien Theorie basiert. Der zweite Teil der Dissertation ist der funktionalen Datenanalyse (FDA), speziell im Zusammenhang mit den Problemen, der empirischen Finanzmarktanalyse gewidmet. Der theoretische Teil der Arbeit konzentriert sich auf die funktionale Hauptkomponentenanalyse -- das funktionale Ebenbild der bekannten Dimensionsreduktionstechnik. Ein umfangreicher überblick der existierenden Methoden wird gegeben, eine Schätzmethode, die von der Lösung des dualen Problems motiviert ist und die Zwei-Stichproben-Inferenz basierend auf der funktionalen Hauptkomponentenanalyse werden behandelt. Die FDA-Techniken sind auf die Analyse der implizierten Volatilitäten- und Zinskurvendynamik angewandt worden. Darüber hinaus, wird die Implementation der FDA-Techniken zusammen mit einer FDA-Bibliothek für die statistische Software Xplore behandelt.
In many different fields of applied statistics an object of interest is depending on some continuous parameter. Typical examples in finance are implied volatility functions, yield curves or risk-neutral densities. Due to the different market conventions and further technical reasons, these objects are observable only on a discrete grid, e.g. for a grid of strikes and maturities for which the trade has been settled at a given time-point. By collecting these functions for several time points (e.g. days) or for different underlyings, a bunch (sample) of functions is obtained - a functional data set. The first topic considered in this thesis concerns the strategies of recovering the functional objects (e.g. implied volatilities function) from the observed data based on the nonparametric smoothing methods. Besides the standard smoothing methods, a procedure based on a combination of nonparametric smoothing and the no-arbitrage-theory results is proposed for implied volatility smoothing. The second part of the thesis is devoted to the functional data analysis (FDA) and its connection to the problems present in the empirical analysis of the financial markets. The theoretical part of the thesis focuses on the functional principal components analysis -- functional counterpart of the well known multivariate dimension-reduction-technique. A comprehensive overview of the existing methods is given, an estimation method based on the dual problem as well as the two-sample inference based on the functional principal component analysis are discussed. The FDA techniques are applied to the analysis of the implied volatility and yield curve dynamics. In addition, the implementation of the FDA techniques together with a FDA library for the statistical environment XploRe are presented.

2016 - 2017
Functional dependencies (FDs) were conceived in the early '70s, and were mainly used to verify database design and assess data quality. However, to solve several issues in emerging application domains, such as the identification of data inconsistencies, patterns of semantically related data, query rewriting, and so forth, it has been necessary to extend the FD definition... [edited by author]
XVI n.s.

This thesis presents strategies for constructing multi-functional biomaterials based on hyaluronan (HA) derivatives for various biomedical applications, such as drug delivery, tissue regeneration, and imaging biomaterials. The aim of this study is to improve the functionalities of HA biomaterials as well as simplify the preparation procedures.  Native HA polymer contains D-glucuronic acid residue with a carboxyl group per disaccharide unit that can be easily modified by carbodiimide-mediated amidation reaction. Therefore, we have designed a series of orthogonal groups (hydrazide, carbazate, aldehyde, and thiol) that can be linked to HA under mild conditions using the carbodiimide chemistry. Multiple functionalities can be introduced to the obtained HA derivatives via chemoselective “click”-type transformations.   The modified HA derivatives were used for the preparation of either nanogel particles (NPs) or bulk hydrogels. Due to “click” character of the reactions used, structural HA transformations were performed with high fidelity on different scales including molecular (polymers), nanometer (NPs), and a visible scale (bulk hydrogels). By linking pyrene or camptothecin to hydrophilic HA backbone, amphiphilic polymers were obtained and utilized as drug delivery carriers or prodrugs, respectively. Subsequently, physically loaded drug (doxorubicin) could be released upon degradation of HA carriers, while the chemically linked camptothecin was released intact by a thiol-triggered cleavage reaction. Bisphosphonated HA (HA-BP) polymers were prepared to induce hydrogel scaffold bio-mineralization for bone regeneration application. Moreover, we could recruit strong binding capacity of bisphosphonate (BP) groups to calcium ions for the formation of physically crosslinked HA-BP gel upon simple mixing of the polymer and calcium phosphate nanoparticle components. This gel was more stable in vivo compared to hydrazone crosslinked HA gels. Furthermore, the hydrogel composed of fluorine-19 (19F) linked HA polymer was successfully observed by both 1H and 19F MR imaging.         In conclusion, the presented herein study describes new approaches for building up multi-functional biomaterials from the HA-based blocks. The utilization of carbodiimide and click chemistries along with the enzymatic degradation of HA allowed simple and efficient interconversion between HA macromolecules, nanoparticles and macroscopic hydrogels. These HA-based biomaterials show high potential for use in the fields of drug delivery, bone regeneration, and imaging techniques.

Medical research currently involves the collection of large and complex data. One such type of data is functional data where the unit of measurement is a curve measured over a grid. Functional data comes in a variety of forms depending on the nature of the research. Novel methodologies are required to accommodate this growing volume of functional data alongside new testing procedures to provide valid inferences. In this dissertation, I propose three novel methods to accommodate a variety of questions involving functional data of multiple forms. I consider three novel methods: (1) a function-on-function regression for Gaussian data; (2) a historical functional linear models for repeated measures; and (3) a generalized functional outcome regression for ordinal data. For each method, I discuss the existing shortcomings of the literature and demonstrate how my method fills those gaps. The abilities of each method are demonstrated via simulation and data application.

In this Thesis a set of functional solid oxides for industrial applications have been addressed by first principles and thermodynamical modelling. More specificially, measurable quantities such as Gibbs free energy, geometry and electronic structure have been calculated and compared when possible with experimental data. These are crystalline and amorphous aluminum oxide (Al2O3), Zirconia (ZrO2), magnesium oxide (MgO), indiumoxide (In2O3) and Kaolinite clay (Al2Si2O5(OH)4). The reader is provided a computation tool box, which contains a set of methods to calculate properties of oxides that are measurable in an experiment. There are three goals which we would like to reach when trying to calculate experimental quantities. The first is verification. Without verification of the theory we are utilizing, we cannot reach the second goal -prediction. Ultimately, this may be (and to some extent already is) the future of first principles methods, since their basis lies within the fundamental quantum mechanics and since they require no experimental input apart from what is known from the periodic table. Examples of the techniques which may provide verification are X-Ray Diffraction (XRD), X-ray Absorption and Emission Spectroscopy (XAS and XES), Electron Energy Loss Spectroscopy and Photo-Emission Spectroscopy (PES). These techniques involve a number of complex phenomena which puts high demands on the chosen computational method/s. Together, theory and experiment may enhance the understanding of materials properties compared to the standalone methods. This is the final goal which we are trying to reach -understanding. When used correctly, first principles theory may play the role of a highly resolved analysis method, which provides details of structural and electronic properties on an atomiclevel. One example is the use of first principles to resolve spectra of multicomponentsamples. Another is the analysis of low concentrations of defects. Thorough analysis of the nanoscale properties of products might not be possible in industry due to time and cost limitations. This leads to limited control of for example low concentrations of defects, which may still impact the final performance of the product. On example within cutting tool industry is the impact of defect contents on the melting point and stability of protective coatings. Such defects could be hardening elements such as Si, Mn, S, Ca which diffuse from a steel workpiece into the protective coating during high temperature machining. Other problems are the solving of Fe from the workpiece into the coating and reactions between iron oxide, formed as the workpiece surface is oxidized, and the protective coating. The second part of the computational toolbox which is provided to the reader is the simulation of solid oxide synthesis. Here, a formation energy formalism, most often applied to materials intended in electronics devices is applied. The simulation of Chemical Vapour Deposition (CVD) and Physical Vapor Deposition (PVD) requires good knowledge of the experimental conditions, which can then be applied in the theoretical simulations. Effects of temperature, chemical and electron potential, modelled concentration and choice of theoretical method on the heat of formation of different solid oxides with and without dopants are addressed in this work. A considerable part of this Thesis is based upon first principles calculations, more specifically, Density Functional Theory (DFT) After Kohn and Pople received the Nobel Prize in chemistry in 1998, the use of DFT for computational modelling has increased strikingly (see Fig. 1). The use of other first principles methods such as hybrid functionals and the GW approach (see abbreviations for short explanations and chapter 4.5 and 5.3.) have also become increasingly popular, due to the improved computational resources. These methods are also employed in this Thesis.
QC 20110201

Thesis (Ph. D.)--Auburn University, 2008.
Abstract. Vita. The following patent resulted from the dissertation research: Davis, V., Simonian, A.L., Nepal, D., Balasubramanian, S, "Preparation of Precisely Controlled Thin Film Nanocomposites of Carbon Nanotubes and Biomaterials", U.S. Provisional Patent Application No. 61/000,938, filed on 30 October 2007. The following peer-reviewed publications resulted from the dissertation research: Dhriti Nepal, Shankar Balasubramanian, Aleksandr Simonian, and Virginia Davis, "Mechanically Strong Antibacterial Thin Film Based on Single-Walled Carbon Nanotubes Armored with Biopolymers", Nano Letters ASAP article, May 2008 (# equal contribution) -- Shankar Balasubramanian, Iryna B. Sorokulova, Vitaly J. Vodyanoy, and Aleksandr L. Simonian, "Lytic Phage as a Specific and Selective Probe For Detection of Staphylococcus Aureus: A Surface Plasmon Resonance Spectroscopic Study", Biosensors and Bioelectronics, 2007, 22, 948-955 -- Shankar Balasubramanian, Alexander Revzin, Aleksandr Simonian, "Electrochemical Desorption of Proteins from Gold Electrode Surface", Electroanalysis, 2006, 18, 1885-1892 (Invited article) -- Vishwaprakash Nanduri, Shankar Balasubramanian, Srinivas Sista, Vitaly J. Vodyanoy, and Aleksandr L. Simonian, "Highly Sensitive Phage-based Biosensor for the Detection of ß-galactosidase", Analytica Chimica Acta, 2007, 589, 166- 172 -- H. Luckarift, Shankar Balasubramanian, S. Paliwal, G. Johnson and A. Simonian, "Enzyme-Encapsulated Silica Monolayers For Rapid Functionalization of a Gold Surface", Colloids and Surfaces B: Biointerfaces, 2007, 58, 28-33 (Invited article) -- Dong Wei, Omar Oyarzabal, Tung-Shi Huang, Shankar Balasubramanian, Srinivas Sista, Aleksandr Simonian, "Development of Surface Plasmon Resonance Biosensor For The Identification of Campylobacter jejuni", Journal of Microbiological Methods, 2007, 69, 78-85. The following conferences presentations resulted from the dissertation research: Covalent Immobilization of Organophosphorus Hydrolase on Carbon Nanotubes for Biosensor Applications, accepted for oral presentation at 12th International Meeting on Chemical Sensors, Jul. 13-16, 2008, Columbus, OH -- Electrochemical characteristics of SWNT-biopolymer nanocomposites, accepted for 213th meeting of The Electrochemical Society, May 18-23, 2008, Phoenix, AR -- Mechanically Robust Antibacterial Thin Films Composed of Single-Walled Carbon Nanotubes and Biopolymers, 2008 AIChE Spring National Meeting, Apr. 6-10, New Orleans, LA -- Production and characterization of protein and DNA based single wall carbon nanocomposites by layer-by-layer assembly, MRS Fall Meeting, Nov. 26-30, 2007, Boston, MA -- Gold surface modified with enzyme-encapsulated silica monolayers for biosensor application, The 58th Southeast Regional Meeting of the American Chemical Society, Nov. 1-4, 2006, Augusta, GA -- Electrochemical modulation of biological interfaces, 209th meeting of The Electrochemical Society, May 7-12, 2006, Denver, CO -- SPR based biosensor using lytic phage as a specific and selective probe for staphylococcus aureus detection, 57th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Mar. 12-17, 2006, Orlando, FL -- Specific & selective detection of staphylococcus aureus by lytic phage using SPR biosensor, 57th Southeast / 61st Southwest Joint Regional Meeting of the American Chemical Society, Nov. 1-4, 2005, Memphis, TN -- Prevention of non-specific binding as a way to increase sensitivity of SPR-based sensors, 206th meeting of The Electrochemical Society, October 3-8, 2004, Honolulu, HI. Includes bibliographical references.

In functional imaging, we are searching for the location of a particular effect in a group of images. It is often of interest to perform a statistical test at each point of the image, and reject the null hypothesis of "no effect" where there is significant evidence to do so. For such purpose, a test statistic should be evaluated at each point of the image, resulting in a test statistic image. The test statistic image can be considered as a stochastic process or a random field, f, defined on some parameter space, T, and taking values in R. When the statistic image, f, is submitted to a threshold of level u the p-value will be the excursion probability. When f satisfies certain conditions, Random Field Theory (RFT) can be used to estimate the above excursion probability by calculating the expected Euler characteristic (EC) of the excursion sets of f. The existing RFT results give explicit formulas for E[EC(Au)] when f is a function of Gaussian random fields [26, 27]. From the "hypothesis testing" point of view, this means that the test performed at each point of the image should be parametric. Parametric tests often assume that the observations are normally distributed and this assumption does not always hold. If this normality assumption fails, the underlying random fields of our test will not be Gaussian, and consequently, the Gaussian RFT results would not be valid.
In this thesis we propose nonparametric counterparts to these parametric tests. Evaluating a nonparametric test statistic at each point of the parameter space, T, results in a random field, which we call a "nonparametric random field". The nonparametric tests used in this work are the Sign test, the Wilcoxon rank-sum test and a general linear rank test. We define the nonparametric random fields precisely, and then derive a formula for E[EC(Au)], when the parameter space is T = [a, b]. Although these results work only for one-dimensional parameter spaces,they constitute a solid first attempt and should pave the way for future generalizations. Moreover, we introduce a new application for the one-dimensional case, in localization of data types, in file type detection studies. We also study the asymptotic behavior of nonparametric random fields and show that the discrete nonparametric fields converge weakly to Gaussian fields, for which we are able to use the existing RFT results. These asymptotic results can be practically used for any dimension. We finally apply these asymptotic results to brain imaging data.
En imagerie fonctionelle, on cherche à localiser un effet particulier à l'aide d'une collection d'images. Il est souvent d'intérêt d'effectuer un test statistique à chaque point de l'image, et de rejeter l'hypothèse nulle stipulant "aucun effet" s'il y a preuve considérable en cette direction. À cette fin, une statistique-test devrait être évaluée à chaque point de l'image, résultant ainsi en une image statistique-test. L'image statistique-test peut être perçue comme étant un procédé stochastique ou un champ aléatoire, f, défini sur un espace-paramètre, T, et avec image en R. Quand l'image statistique-test, f, est soumise à un seuil de niveau u la p-valeur sera la probabilité d'excursion. Quand f satisfait certaines conditions, la Théorie des Champs Aléatoires (TCA) peut être utilisée afin d'estimer cette probabilité d'excursion en calculant l'espérance mathématique de la caractérisque d'Euler (CE) des ensembles d'excursion de f. Les résultats de la TCA déjà établis procurent des formules explicites pour E[EC(Au)] quand f est une fonction de champs gaussiens [26, 27]. De la perspective des tests d'hypothèse, ceci implique que le test effectué à chaque point de l'image devrait être paramétrique. Les tests paramétriques requièrent fréquemment que les observations soient normalement distribuées, bien que cette hypothèse ne soit pas toujours vraie. Si l'hypothèse de normalité est fausse, les champs aléatoires obtenues à partir de notre statistique-test ne sont pas gaussiens et conséquemment, les résultats de la TCA gaussiens sont invalides.
Dans cette thèse, on propose un homologue non-paramétrique aux tests paramétriques. L'évaluation d'une statistique-test nonparamétrique à chaque point de l'espace-paramètre, T, résulte en un champ aléatoire, que l'on nommera " champ aléatoire non-paramétrique. " Les tests non-paramétriques utilisés dans ce travail sont le test du signe, le test de la somme des rangs de Wilcoxon et le test de rangs linéaire général. On définit précisément le champ aléatoire non-paramétrique, pour ensuite dériver une formule pour E[EC(Au)] quand l'espace-paramètre est T = [a, b]. Bien que ces résultats soient uniquement valides pour des espaces-paramètre unidimensionels, ils constituent un premier pas important et devrait frayer la voie à de plus amples généralisations. De plus, on introduit une nouvelle application pour le cas unidimensionel, notamment concernant la localisation de types de données lors d'études de détection de types de fichiers. On étudie également le comportement asymptotique des champs aléatoires non-paramétriques et démontre que les champs aléatoires discrets converge faiblement vers des champs gaussiens, pour lesquelles les résults de la TAC sont applicables. Ces résultats asymptotiques s'avèrent utiles pour toute dimension. On applique finalement ces résultats asymptotiques à des données d'imagerie cervicale.

Lanthanide-doped upconversion nanoparticles (UCNPs) are perceived as promising novel near-infrared (NIR) bioimaging agents characterised by high contrast and high penetration depth. However, the interactions between charged UCNPs and mammalian cells have not been thoroughly studied and the corresponding intracellular uptake pathways remain unclear. Herein, my research work involved the use of hydrothermal method and ligand exchange approach to prepare UCNP-PVP, UCNP-PEI, and UCNP-PAA. These polymer-coated UCNPs demonstrated good water dispersibility, the similar size distribution as well as similar upconversion luminescence efficiency. However, the positively charged UCNP-PEI evinced greatly enhanced cellular uptake in comparison with its neutral or negative counterparts, as revealed by cellular uptake studies. Meanwhile, it was discovered that cationic UCNP-PEI could be effectively internalized mainly through the clathrin endocytic machanism. This study is the first report on the endocytic mechanism of positively charged lanthanide-doped UCNPs. Furthermore, it allows us to control the UCNP-cell interactions by tuning surface properties. Glioblastoma multiforme (GBM) is the most common and malignant form of primary brain tumors in humans. Small molecule MRI contrast agents are used for GBM diagnosis and preoperative tumor margin delineation. However, the conventional gadolinium-based contrast agents have several disadvantages, such as a relatively low T1 relaxivity, short circulation half lives and the absence of tumor targeting efficiency. Multimodality imaging probes provide a better solution to clearly delineate the localization of glioblastoma. My research work also involved the development of multimodal nanoprobes for targeted glioblastoma imaging. Two targeted paramagnetic/fluorescence nanoprobes were designed and synthesized, UCNP-Gd-RGD and AuNP-Dy680-Gd-RGD. UCNP-Gd-RGD was prepared through PEGylation, Gd3+DOTA conjugation and RGD labeling of PEI-coated UCNP-based nanoprobe core (UCNP-NH2). It adopted the cubic NaYF4 phase, had an average size of 36 nm by TEM, and possessed a relatively intense upconversion luminescence of Er3+ and Tm3+. It also exhibited improved colloidal stability and reduced cytotoxicity compared with UCNP-NH2, and a higher T1 relaxivity than Gd3+DOTA. AuNP-Dy680-Gd-RGD was synthesized through bioconjugation of amine-modified AuNP-based nanoprobe core (AuNPPEG- NH2) by a NIR dye (Dy680), Gd3+DOTA and RGD peptide. It demonstrated a size of 3–6 nm by TEM, relatively strong NIR fluorescence centered at 708 nm, longterm physiological stability, and an enhanced T1 relaxivity compared with Gd3+DOTA. Targeting abilities of both UCNP-Gd-RGD and AuNP-Dy680-Gd-RGD towards overexpressed integrin αvβ3 receptors on U87MG cell surface was confirmed by their enhanced cellular uptake visualized by confocal microscopy imaging and quantified by ICP-MS, where their corresponding control nanoprobes were used for comparison. Furthermore, targeted imaging capabilities of UCNP-Gd-RGD and AuNP-Dy680-Gd- RGD towards subcutaneous U87MG tumors were verified by in vivo and ex vivo upconversion fluorescence imaging studies and by in vivo and ex vivo NIR fluorescence imaging and in vivo MR imaging studies, respectively. These two synthesized targeted nanoprobes, with surface-bounded cyclic RGD peptide and numerous T1 contrast enhancing molecules, are applicable in targeted MR imaging glioblastoma and delineating the tumor boundary. In addition, UCNP-Gd-RGD favors the upconversion luminescence with NIR-to-visible nature, while AuNPDy680- Gd-RGD possesses NIR-to-NIR fluorescence, and both lead to their potential applications in fluorescence-guided surgical resection of gliomas.
published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy

Polymer-based piezoelectric and triboelectric generators form the basis of well-known energy harvesting methods that are capable of transforming ambient vibrational energy into electrical energy via electrical polarization changes in a material and contact electrification, respectively. However, the low energy conversion efficiency and limited thermal stability of polymeric materials hinder practical application. While nanostructured polymers and polymer-based nanocomposites have been widely studied to overcome these limitations, the performance improvement has not been satisfactory due to limitations pertaining to long-standing problems associated with polymeric materials; such as low crystallinity of nanostructured polymers, and in the case of nanocomposites, poor dispersion and distribution of nanoparticles in the polymer matrix. In this thesis, novel functional polymeric nanomaterials, for stable and physically robust energy harvesting applications, are proposed by developing advanced nanofabrication methods. The focus is on ferroelectric polymeric nanomaterials, as this class of materials is particularly well-suited for both piezoelectric and triboelectric energy harvesting. The thesis is broadly divided into two parts. The first part focuses on Nylon-11 nanowires grown by a template-wetting method. Nylon-11 was chosen due to its reasonably good ferroelectric properties and high thermal stability, relative to more commonly studied ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)). However, limitations in thin-film fabrication of Nylon-11 have led to poor control over crystallinity, and thus investigation of this material for practical applications had been mostly discontinued, and its energy harvesting potential never fully realised. The work in this thesis shows that these problems can be overcome by adopting nanoporous template-wetting as a versatile tool to grow Nylon-11 nanowires with controlled crystallinity. Since the template-grown Nylon-11 nanowires exhibit a polarisation without any additional electrical poling process by exploiting the nanoconfinement effect, they have been directly incorporated into nano-piezoelectric generators, exhibiting high temperature stability and excellent fatigue performance. To further enhance the energy harvesting capability of Nylon-11 nanowires, a gas -flow assisted nano-template (GANT) infiltration method has been developed, whereby rapid crystallisation induced by gas-flow leads to the formation of the ferroelectric δʹ-phase. The well-defined crystallisation conditions resulting from the GANT method not only lead to self-polarization but also increases average crystallinity from 29 % to 38 %. δʹ-phase Nylon-11 nanowires introduced into a prototype triboelectric generator are shown to give rise to a six-fold increase in output power density as observed relative to the δʹ-phase film-based device. Interestingly, based on the accumulated understanding of the template-wetting method, Nylon-11, and energy harvesting devices, it was found that thermodynamically stable α-phase Nylon-11 nanowires are most suitable for triboelectric energy generators, but not piezoelectric generators. Notably, definitive dipole alignment of α-phase nanowires is shown to have been achieved for the first time via a novel thermally assisted nano-template infiltration (TANI) method, resulting in exceptionally strong and thermally stable spontaneous polarization, as confirmed by molecular structure simulations. The output power density of a triboelectric generator based on α-phase nanowires is shown to be enhanced by 328 % compared to a δʹ-phase nanowire-based device under the same mechanical excitation. The second part of the thesis presents recent progress on polymer-based multi-layered nanocomposites for energy harvesting applications. To solve the existing issues related to poor dispersion and distribution of nanoparticles in the polymer matrix, a dual aerosol-jet printing method has been developed and applied. As a result, outstanding dispersion and distribution. Furthermore, this method allows precise control of the various physical properties of interest, including the dielectric permittivity. The resulting nanocomposite contributes to an overall enhancement of the device capacitance, which also leads to high-performance triboelectric generators. This thesis therefore presents advances in novel functional polymeric nanomaterials for energy harvesting applications, with improved performance and thermal stability. It further offers insight regarding the long-standing issues in the field of Nylon-11, template-wetting, and polymer-based nanocomposites.

Porous materials are useful in various energy and environmental applications such as electrodes for supercapacitive energy storage, gas storage media, and sieves for the removal of toxic chemicals. Carbonaceous materials derived from biomass have been widely used, but the properties obtained are variable as a result of the variation in the composition of the biomass often used to form them. The use of functionalised polymers as carbonisation precursors allows greater control of the structure and heteroatom doping in the resulting carbon. This thesis examines the largely unexplored route of carbonising porous organic networks, which have multiple advantages over non-porous and pre-carbonised analogues. This yields interesting properties for energy and gas storage applications. Only a few papers had been published in this area prior to the start of this PhD project, and there were no reports of carbonisation for the polymer networks investigated here. Thus, a range of methods and conditions were tested to prepare materials with excellent performance in their respective applications. This project also tackles the problem of toxic mercury contamination in water by developing microporous materials synthesised from low-cost, waste by-products.

Although cytoplasmic lipid droplets (LDs) are the major reserves for energy-dense neutral lipids in plants, the cellular mechanisms for packaging neutral lipids into LDs remain poorly understood. To gain insights into the cellular processes of neutral lipid accumulation and compartmentalization, a necessary step forward would be to characterize functional roles of lipogenic proteins that participate in the compartmentalization of neutral lipids in plant cells. In this study, the lipogenic proteins, Arabidopsis thaliana SEIPIN homologues and mouse (Mus Musculus) fat storage-inducing transmembrane protein 2 (FIT2), were characterized for their functional roles in the biogenesis of cytoplasmic LDs in various plant tissues. Both Arabidopsis SEIPINs and mouse FIT2 supported the accumulation of neutral lipids and cytoplasmic LDs in plants. The three Arabidopsis SEIPIN isoforms play distinct roles in compartmentalizing neutral lipids by enhancing the numbers and sizes of LDs in various plant tissues and developmental stages. Further, the potential applications of Arabidopsis SEIPINs and mouse FIT2 in engineering neutral lipids and terpenes in plant vegetative tissues were evaluated by co-expressing these and other lipogenic proteins in Nicotiana benthamiana leaves. Arabidopsis SEIPINs and mouse FIT2 represent effective tools that may complement ongoing strategies to enhance the accumulation of desired neutral lipids and terpenes in plant vegetative tissues. Collectively, our findings in this study expand our knowledge of the broader cellular mechanisms of LD biogenesis that are partially conserved in eukaryotes and distinct in plants and suggest novel targets that can be introduced into plants to collaborate with other factors in lipid metabolism and elevate oil content in plant tissues.

Background: Kisspeptins, recently discovered hypothalamic neuropeptides encoded by the KISS1 gene, are essential for normal pubertal development and are modulated by diverse endocrine, metabolic and environmental signals. Exogenous kisspeptin administration potently stimulates LH secretion - by direct action on GnRH neurons while kisspeptin antagonists inhibit pulsatile LH secretion. Human studies of kisspeptin had hitherto used kisspeptin-54 that is cleaved further and the smallest bioactive form is a decapeptide (kisspeptin-10) with a shorter half-life. Kisspeptin-10 is thus putatively more attractive in studies assessing LH pulsatility and is also the basis for the development of antagonists. Unmet clinical needs: Decreased LH pulse frequency is the central pathology in pubertal delay, late-onset male hypogonadism and hypothalamic amenorrhoea. Manipulation of LH pulse frequency also has therapeutic potential in contraception, PCOS and sex-steroid dependant diseases such as endometriosis and prostatic hyperplasia. Hypothesis: That exogenous kisspeptin-10 enhances pulsatile LH secretion in healthy men and in patients with reproductive disorders associated with decreased pulse frequency. Research strategy: A first-in-human dose escalation study of kisspeptin-10 was performed in men and subsequently replicated in women. An intravenous infusion regime was optimised in healthy men and subsequently applied to hypogonadal patients. Specific questions were addressed sequentially as summarised below with key results. Dose escalation study: Question: Does kisspeptin-10 stimulate LH secretion in men? Findings: Six iv bolus doses (0.01 to 3 μg/kg) of GMP kisspeptin-10 and vehicle were administered at least a week apart to six healthy men. Rapid increase in LH, with peak concentrations was seen by 45 min post injection in all volunteers. There was a clear dose-dependent increase in LH concentrations in response to kisspeptin- 10 (P <0.0001). Area-Under-Curve analysis over 60 min following kisspeptin-10 administration showed 0.3 and 1μg/kg doses to be maximally stimulatory (P <0.01) with a reduced response at 3 μg/kg. Assessing the effect of steroid milieu: Question: Steroid feedback is central to the regulation of LH secretion: what effect does the steroid milieu have on LH responses to kisspeptin-10? Findings: The response to iv kisspeptin-10 (0.3μg/kg,) in the normal follicular phase (n=10) was compared with that in the presence of low endogenous sex steroids/high LH secretion (6 postmenopausal women) and in women taking combined contraceptive therapy (n=8) with suppressed LH secretion. Despite widely varying baseline secretion, LH increased significantly following kisspeptin-10 administration in the follicular phase (6.3±1.2 to 9.4±1.3 IU/L P=0.006), postmenopausal (35.3±2.8 to 44.7±3.4 IU/L P=0.005), etonogestrel (4.6±0.2 to 7.5±0.9 IU/L, P=0.02), and COCP groups (2.2±0.9 to 3.7±1.4 IU/L P<0.001). Pulse frequency study: Question: GnRH and LH secretion are pulsatile: can kisspeptin-10 enhance LH pulsatility? Findings: Four healthy men attended our clinical research facility for two visits five days apart for 10-min blood sampling. At the first visit, baseline LH pulsatility was assessed over a 9-hour period. During the second visit, an infusion of kisspeptin-10 was administered for 9 hours at 1.5μg/kg/hr after an hour of baseline sampling. LH pulse frequency increased in all subjects, with a mean increase from 0.7±0.1 to 1.0±0.2 pulses/hr (P = 0.01), with resultant increase in mean LH from 5.2±0.8 IU/L at baseline to 14.1±1.7 IU/L (P <0.01). High dose, longer duration infusion study: Question: Can kisspeptin-10 enhance testosterone secretion? Findings: Four healthy men attended our clinical research facility for a 34-hour supervised stay. Blood samples were collected at 10 min intervals for two 12 hour periods on consecutive days and hourly overnight. After 10.5 hours of baseline sampling a continuous intravenous infusion of kisspeptin-10 (4μg/kg/hr) was maintained for 22.5 hrs. Mean LH increased from 5.5±0.8 at baseline to 20.9±4.9 IU/L (P <0.05) and serum testosterone increased from 16.6±2.4 to 24.0±2.5 nmol/L (P <0.001). Translational studies in hypogonadal men with type 2 diabetes Question: Can kisspeptin-10 normalise testosterone secretion in hypogonadal men? Findings: Five hypogonadal men with T2DM (age 33.6±3 yrs, BMI 40.6±6.3, testosterone 8.5±1.0 nmol/L, LH 4.7±0.7 IU/L, HbA1c <8 %, duration of diabetes <5 yrs) and seven age matched healthy men were studied. Kisspeptin-10 was administered intravenous (0.3 μg/kg) with frequent (10-min) blood sampling. Mean LH increased in controls (5.5±0.8 to 13.9±1.7 IU/L P <0.001) and in T2DM (4.7±0.7 to 10.7±1.2 IU/L P=0.02) with comparable ΔLH (P=0.18). Baseline serum sampling for LH at 10-min intervals and hourly testosterone measurements were performed subsequently in four T2DM men for 12 hours. An intravenous infusion of kisspeptin-10 (4 μg/kg/hr) was administered 5 days later for 11 hours, with increases in serum LH (3.9±0.1 IU/L to 20.7±1.1 IU/L (P=0.03,) and testosterone (8.5±1.0 to 11.4±0.9 nmol/L, P=0.002). LH pulse frequency at baseline was lower in hypogonadal men with diabetes (0.6±0.1 vs. 0.8±0.1 pulses/hr, P=0.03) and increased to 0.9±0 pulses/hr (P=0.05). Translational studies in pubertal delay: Question: Defective Neurokinin B activity is associated with pubertal delay and the hierarchical interactions between kisspeptins and Neurokinin B remain to be elucidated: can kisspeptin-10 stimulate LH secretion with impaired Neurokinin B signalling? Findings: Four patients with TAC3 or TACR3 inactivating mutations presenting with delayed puberty were admitted for two 12 hr blocks of blood sampling every 10 min with vehicle (saline) or kisspeptin-10 (1.5 μg/kg/hour) infused intravenously. Mean LH and LH pulses frequency increased with kisspeptin-10 (P<0.05). However, four patients with Kallmann syndrome (with defective GnRH neuron migration), studied in parallel, did not respond, suggesting a potential diagnostic application for kisspeptin-10 in pubertal dysfunction. Conclusions In first-in-man studies of kisspeptin-10, it was demonstrated that endogenous LH pulse frequency can be enhanced in healthy men. The therapeutic potential of this finding in common reproductive endocrine disorders associated with decreased LH pulse frequency, i.e., late-onset male hypogonadism and pubertal dysfunction, was suggested in subsequent studies. Furthermore, kisspeptin signalling occurs upstream of GnRH neurons and is independent of Neurokinin B signalling in the central regulation of the hypothalamic-pituitary-gonadal axis.

El diòxid de carboni (CO2) ha estat present en l'atmosfera des de les primeres etapes de la Terra. El CO2 és un dels gasos responsables de l'efecte hivernacle, que regula la temperatura de la superfície del planeta. No obstant això, la seva concentració a l'atmosfera ha anat creixent de forma exponencial des de la revolució industrial, especialment en l'últim segle, el que ha implicat un efecte negatiu en el clima global. És per això que el desenvolupament de noves transformacions del CO2 amb l'objectiu de reduir els nivells atmosfèrics s'ha convertit en un camp actiu d'investigació en les últimes dècades. El nostre grup s'ha centrat en la utilització de CO2 per a la síntesi de carbonats cíclics (CCs) mitjançant la cicloaddició [3 + 2]. En aquest context, el capítol 2 descriu la síntesi i caracterització de cinc estèreo / regio-isòmers de CCs a partir d'un sol epoxialcohol, derivat del ciclooctadié, incloent dos CCs amb configuració trans i per tant amb potencial en l'aplicació de polimerització per "Ring Opening Polymeization"(ROP). El tercer capítol es centra en la síntesi de carbonats cíclics de 6 membres (6MCCs) mitjançant un procés fotocatalític. També s'avalua el potencial d'alguns dels 6MCCs preparats en ROP. Finalment, el capítol 4 resumeix els nostres esforços per sintetitzar "nonisocyanate polyurethanes" (NIPU) a partir d'un dicarbonat derivat de beta-elemé i diaminas comercialment rellevants. En aquest capítol també es discuteixen les propietats físiques d'un dels NIPUs sintetitzats.
El dióxido de carbono (CO2) ha estado presente en la atmósfera desde las primeras etapas de la Tierra. El CO2 es uno de los gases responsables del efecto invernadero, que regula de la temperatura de la superficie del planeta. Sin embargo, su concentración en la atmósfera ha ido creciendo de forma exponencial desde la revolución industrial, especialmente en el último siglo, lo que ha implicado un efecto negativo en el clima global. Es por esto que el desarrollo de nuevas transformaciones de CO2 con el objetivo de reducir los niveles atmosféricos se ha convertido en un campo activo de investigación en las últimas décadas. Nuestro grupo se ha centrado en la utilización de CO2 para la síntesis de carbonatos cíclicos (CCs) mediante la cicloadición [3 + 2]. En este contexto, el capítulo 2 describe la síntesis y caracterización de cinco estereo/regio-isómeros de CCs a partir de un solo epoxialcohol ,derivado del ciclooctadieno, incluyendo dos CCs con configurados trans y por tanto con potencial en la aplicación de polimerización por "Ring Opening Polymeization" (ROP). El tercer capítulo se centra en la síntesis de carbonatos cíclicos de 6 miembros (6MCCs) mediante un proceso fotocatalítico. También se evalúa el potencial de algunos de los 6MCCs preparados en ROP. Finalmente, el capítulo 4 resume nuestros esfuerzos para sintetizar "non-isocyanate polyurethanes" (NIPUs) a partir de un dicarbonato derivado de beta-elemeno y diaminas comercialmente relevantes. En este capítulo también se discuten las propiedades físicas de uno de los NIPUs sintetizados
Carbon dioxide (CO2) has been present in atmosphere since early stages of the Earth. CO2 is one of the gases components responsible of the greenhouse effect, responsible of the regulation of the planet surface temperature. However its concentration in the atmosphere has been growning dramatically since the industrial revolution, specially in the last century which has implied a negative effect in the global climate. In this concern, developing new CO2 transformation with the aim of reducing atmospheric levels has become an active field of research in the last decades. Our group has focused in the utilization of CO2 for the synthesis of cyclic carbonates (CCs) via [3+2] cycloaddition. In this context, chapter 2 describes the synthesis and characterization of five CCs stereo/regio-isomers from a single epoxyalcohol derived from cyclooctadiene, including two unusual trans-configured CCs with potential in Ring Opening Polymerization (ROP) application. The third chapter focuses in the synthesis of 6-membered cyclic carbonates (6MCCs) by means of a photocatalytic process. The ROP potential of some of the 6MCCs prepared is also evaluated. Finally, chapter 4 summarises our efforts to synthesize non-isocyanate polyurethanes (NIPUs) from a biobased dicarbonate monomer, derived from beta-elemene and commercially relevant diamines. In this chapter the physical properties of one of the NIPUs synthesized are also discussed

Doutoramento em Ciência e Engenharia de Materiais
Devido à redução de dimensões e ao aumento da velocidade de processamento de dados nos dispositivos microeletrónicos baseados em semicondutores convencionais, estão a ser exploradas abordagens inovadoras envolvendo novos materiais tais como óxidos funcionais. Com o rápido desenvolvimento da indústria eletrónica existe uma maior necessidade de elevado desempenho, de elevada fiabilidade, e de componentes eletrónicos miniaturizados integrados em vários dispositivos. A fim de tornar os dispositivos amplamente acessíveis e de fácil utilização, requisitos adicionais devem ser considerados: o tamanho e peso desejados, o custo reduzido, o baixo consumo de energia e a portabilidade. Materiais funcionais de baixa dimensionalidade são muito promissores para cumprir essas exigências. Em particular, os ferroeléctricos de filmes finos bidimensionais (2D) têm recebido grande atenção devido à sua crescente utilização em memórias não voláteis, detectores piroelétricos, transdutores piezoeléctricos miniaturizados e dispositivos sintonizáveis de micro-ondas. A temperatura de cristalização é um parâmetro chave na preparação de ferroelétricos 2D. Muitos filmes finos ferroelétricos são cristalizados a temperaturas >600 °C. Esses valores estão acima da temperatura que certos elementos do dispositivo funcional podem suportar. Recentemente, este facto tornou-se ainda mais importante, devido às promissoras aplicações que podem ser consideradas caso os ferroeléctricos 2D sejam compatíveis com substratos poliméricos flexíveis de baixo custo e de baixo ponto de fusão. A compatibilidade de filmes finos ferróicos com estes últimos tipos de substratos é muito difícil, mas se conseguida pode ampliar acentuadamente a gama de aplicações para os mais recentes requisitos de eletrónica flexível e microeletrónica, onde dispositivos leves e baratos são exigidos. Neste trabalho, é implementada uma combinação da modificação da química de precursores e assistência por luz UV, com promoção simultânea da cristalização pela introdução de sementes nanocristalinas na solução precursora, para a fabricação de filmes finos ferróicos sem chumbo - Método de Precursores Fotossensíveis Semeados. Neste contexto, o principal objetivo deste trabalho foi fabricar filmes finos sem chumbo BiFeO3 (BFO) e Na0.5Bi0.5TiO3 (NBT) a baixas temperaturas (~300 °C) com uma resposta ferroelétrica competitiva. Além disso, a investigação do efeito do elétrodo-base sobre as propriedades dielétricas e ferroelétricas de filmes finos de BFO foi levada a cabo, e a comparação entre o comportamento de condensadores de BFO com base em IrO2, LaNiO3 (LNO) e Pt foi estabelecida. Adicionalmente, os efeitos dos vários eléctrodos sobre a microestrutura de filmes finos ferroeléctricos de BFO foram estudados por microscopia eletrónica de transmissão (TEM) de alta resolução. Primeiramente, filmes finos finos de perovesquite BFO e NBT foram preparados sobre substratos de silício revestidos com Pt, por deposição de solução química. Os filmes finos de BFO foram preparados a temperaturas na gama de 400-500 °C, a partir de soluções de precursores estequiométricas e com excesso de Bi. Os filmes de BFO cristalinos foram obtidos a 400 °C, o limite inferior de temperatura. Os filmes preparadas com excesso de Bi possuem curvas de histerese ferroelétrica mais definidas do que aqueles sem qualquer excesso, para filmes com espessuras ~150 nm. Uma vez que as densidades de corrente de fuga nos filmes finos diminuem com a diminuição da temperatura de processamento, a polarização de filmes finos de BFO preparados com excesso Bi e recozidos a 400 e 450 °C pode ser efetivamente comutada à temperatura ambiente. Obtiveram-se valores de polarização remanescente de Pr ~10 e ~60 μC/cm2 com campos coercivos de EC ~ 205 e 235 kV/cm para os filmes finos preparados a 400 e 450 °C, respectivamente. Os filmes finos de NBT foram preparados a temperaturas entre 400 e 650 °C. As propriedades estruturais e ferroelétricas dos filmes foram examinadas. A constante dieléctrica observada e as perdas dieléctricas a 100 kHz são 616 e 0,032, respectivamente, enquanto que a polarização remanescente observada e o campo coercivo são Pr ~ 24 μC/cm2 e EC ~ 215 kV/cm, respectivamente para o filme de NBT recozido a 650 °C. O recozimento térmico, em atmosfera de oxigénio após cada camada de revestimento, é eficaz na promoção da cristalização do filme na fase de perovesquite romboédrica a uma baixa temperatura de 400 °C. No entanto, obteve-se um ciclo P-E quase linear para os filmes NBT cristalizados a 400 °C devido à sua incipiente cristalinidade. Os filmes finos de BFO foram depositados numa gama de elétrodos para determinar o seu papel no controlo da formação de fases e da microestrutura. A cristalização em elétrodos de óxido seguiu a sequência: amorfa → Bi2O2(CO3) → perovesquite, enquanto que nos elétrodos de Pt cristalizaram diretamente a partir da fase amorfa. Os elétrodos de IrO2 promoveram a formação da fase de perovesquite à temperatura mais baixa e o LNO induziu adicionalmente o crescimento epitaxial local. O LNO tem a estrutura de perovesquite com o parâmetro de rede a = 0.384 nm, compatível com o de BFO, a = 0.396 nm, e assim a epitaxia é mais provável. Todas as composições exibiram precipitados inteiramente coerentes ricos em Fe dentro do interior de grão da matriz de perovesquite, enquanto que a incoerente segunda fase de Bi2Fe4O9 foi também observada nos limites de grão de BFO crescido em eléctrodos de Pt. Esta última pode ser observada por difração de raios X, bem como TEM, mas os precipitados coerentes foram observados apenas por TEM, principalmente evidenciados pelo seu contraste Z em imagens de campo escuro anular. Estes dados têm consequências acentuadas permitindo alargar a utilização de filmes de BFO sob campo aplicado, a aplicações como atuadores, sensores e aplicações de memória. Em seguida, os filmes finos de BFO foram depositados em substratos de Si com elétrodos distintos, como Pt, LNO e IrO2, para investigar o efeito do elétrodo-base sobre o crescimento e as propriedades elétricas do BFO. Todas os filmes de BFO são compostos por grãos colunares cujo tamanho é dependente do elétrodo-base. Não se observou textura para filmes de 320 nm de espessura fabricados em Pt orientado (111). Os filmes sobre eléctrodos de óxido, em particular sobre LNO são altamente orientados no plano (012). A grande polarização remanescente em BFO/Pt e BFO/IrO2 é atribuída à alta contribuição de corrente de fuga. Os filmes BFO de 400 nm de espessura em LNO possuem uma baixa densidade de corrente de fuga ~4 × 10-6 A/cm2, uma grande polarização remanescente de 50 μC/cm2 e um pequeno campo coercitivo de 180 kV/cm à temperatura ambiente. Demonstramos que as camadas de LNO aumentam a cristalinidade e a orientação de filmes finos BFO, o que se reflete nas suas propriedades funcionais. Este estudo mostra que, além da simples necessidade de filmes monofásicos, os elétrodos de óxido de metal têm um impacto relevante no desenvolvimento de filmes finos BFO de alta qualidade fabricados por métodos químicos de deposição de solução. Estes resultados têm uma implicação grande para a fabricação de dispositivos BFO baseados em filmes finos. Finalmente, provamos que é possível fabricar diretamente filmes finos de BFO sem chumbo em substratos flexíveis de poliamida com funcionalidades ferroelétricas e magnéticas (multiferroicidade) à temperatura ambiente. O nosso método inovador, baseado em soluções de Precursores Fotossensíveis e nanosementes cristalinas, foi usado com sucesso para diminuir a temperatura de cristalização de filmes finos de BFO até uma temperatura tão baixa quanto 300 °C, a mais baixa temperatura reportada até agora para a preparação de filmes finos multiferróicos de BFO. Apesar deste excepcionalmente baixo nível térmico, obtém-se uma polarização remanescente Pr de 2.8 μC/cm2 para os filmes semeados + UV, com um campo coercitivo EC de 300 kV/cm. A estratégia de síntese baseada na utilização de precursores fotossensíveis sementados pode ser transferida para qualquer outra família de óxidos metálicos funcionais.
With the dimensions reduction and data processing speeds increasing of conventional semiconductor based microelectronic devices, innovative approaches involving new materials such as functional oxides are being explored. With the rapid development of the electronics industry there is a need for high performance, high reliability and miniaturized electronic components integrated into various devices. In order to make the devices user friendly and widely accessible, additional requirements should be considered: the desired size and weight, low cost, low power consumption, and portability in addition to high levels of functionality. Low dimensional functional materials hold great promises to fulfil those requirements. In particular, two-dimensional (2D) thin film ferroelectrics have received wide attention because of their growing use as non-volatile memories, pyroelectric detectors, miniaturized piezoelectric transducers and tunable microwave devices. Crystallization temperature is a key parameter in preparation of 2D-ferroelectrics. Many ferroelectric thin films are crystallized at temperatures >600 °C. This is above the temperature that certain elements of the functional device can withstand. Recently it became even more important due to promising applications that can be envisaged if 2D-ferroelectrics will be compatible with low cost, low melting temperature flexible polymeric substrates. The compatibility of ferroic thin films with those last types of substrates can markedly widen the range of applications towards the most recent requirements of flexible electronics and microelectronics, where lightweight and cheap devices are demanded. In this work, a combination of the modification of precursor chemistry and the assistance of UV-light, with simultaneous promotion of crystallization by introducing nanocrystalline seeds in the precursor solution, is implemented to fabricate lead-free ferroic thin films - Seeded Photosensitive Precursor Method. Within this context, the main objective of this work was to fabricate lead-free BiFeO3 (BFO) and Na0.5Bi0.5TiO3 (NBT) thin films with a competitive ferroelectric response at low temperatures. Moreover, investigations of the effect of the bottom electrode on the dielectric and ferroelectric properties of BFO thin films was conducted and the comparison between the behavior of IrO2, LaNiO3 (LNO) and Pt based BFO capacitors established. Additionally, the effects of these various bottom electrodes on the microstructure of BiFeO3 ferroelectric films was studied by high-resolution TEM. Firstly, BFO and NBT perovskite thin films were prepared on Pt-coated silicon substrates by chemical solution deposition. BFO was prepared at temperatures in the range 400-500 °C, and from stoichiometric and Bi excess precursor solutions. Crystalline BFO films were obtained at the lowest temperature limit of 400 °C. The films prepared with Bi excess possess more defined ferroelectric hysteresis loops than those without any excess; for films with thicknesses ~150 nm. As the leakage current densities in the films decrease with decreasing the processing temperature, polarization of BFO films prepared with Bi excess and annealed at 400 and 450 °C can be effectively switched at room temperature. Remanent polarization values of Pr ~ 10 and ~60 μC/cm2 with coercive fields of EC ~ 205 and 235 kV/cm were obtained for the films prepared at 400 and 450 °C, respectively. NBT thin films were prepared at temperatures from 400 to 650 °C. Structural and ferroelectric properties of the films were examined. The observed dielectric constant and dielectric losses at 100 kHz are 616 and 0.032, respectively, while the observed remanent polarization and coercive field are Pr ~ 24 μC/cm2 and EC ~ 215 kV/cm, respectively for the NBT film annealed at 650 °C. Thermal annealing in an oxygen atmosphere after each layer of coating is effective in promoting crystallization of the film into rhombohedral perovskite phase at a low temperature of 400 °C. However, almost linear, P-E loop was obtained for those NBT films crystallized at 400 °C due to incipient crystallinity. BFO thin films were grown on a range of electrodes to determine their role in controlling phase formation and microstructure. The crystallization on oxide electrodes followed the sequence: amorphous → Bi2O2(CO3) → perovskite, while those on Pt crystallized directly from the amorphous phase. IrO2 electrodes promoted perovskite phase formation at the lowest temperature and LaNiO3 additionally induced local epitaxial growth. LNO has the perovskite structure with lattice parameter a = 0.384 nm, compatible with that of BFO, a = 0.396 nm and thus epitaxy is more likely. It was observed for the first time that all compositions exhibited fully coherent Fe-rich precipitates within the grain interior of the perovskite matrix, whereas incoherent Bi2Fe4O9 second phase was also observed at the grain boundaries of BFO grown on Pt electrodes. The latter could be observed by X-ray diffraction as well as transmission electron microscopy (TEM) but coherent precipitates were only observed by TEM, principally evidenced by their Z contrast in annular dark field images. These data have pronounced consequences for the extended use of BFO films under applied field for actuator, sensor and memory applications. Then, BFO thin films were deposited on Si-based substrates with distinct electrodes, such as Pt, LNO, and IrO2, in order to investigate the effect of bottom electrode on the growth and electrical properties of BFO. All BFO films are composed of columnar grains which size is dependent on the bottom electrode. No texture was observed for 320 nm thick films fabricated on (111) oriented Pt. Films on oxide electrodes, in particular on LNO are highly (012) oriented. The large remanent polarization in BFO/Pt and BFO/IrO2 is attributed to the high leakage current contribution. 400 nm thick BFO films on LNO possess a low leakage current density ~4 × 10-6 A/cm2, a large remanent polarization of 50 μC/cm2 and a small coercive field of 180 kV/cm at room temperature. We demonstrate that LNO layers enhance the crystallinity and orientation of BFO thin films, which is reflected in their functional properties. This study shows that besides the simple need of monophasic films metal oxide electrodes have a relevant impact on the development of high quality BFO thin films fabricated by chemical solution deposition methods. These results have a broad implication for the fabrication of BFO thin film based devices. Finally, we prove that it is possible to directly fabricate lead-free BFO thin films on flexible polyamide substrates with ferroelectric and magnetic functionalites (multiferroicity) at room temperature. Our own proprietary novel solution-based Seeded Photosensitive Precursor Method was successfully used to decrease the crystallization temperature of BFO thin films down to a temperature as low as 300 °C, the lowest reported up to now for the preparation of multiferroic BFO thin films. Despite this exceptionally low thermal budget a remanent polarization Pr of 2.8 μC/cm2 is obtained for the seeded + UV films, with a coercive field EC of 300 kV/cm. The synthesis strategy based on the use of seeded photosensitive precursors can be transferred to any family of functional metal oxide.

With so many developers writing code, so many choose to become a developer every day, using tools to aid in the work process is needed. With all the testing being done for multiple different devices and sources there is a need to make it better and more efficient. In this thesis connecting the variety of different tools such as version control, project management, issue tracking and test systems is explored as a possible solution. A possible solution was implemented and then analyzed through a questionnaire that were answered by developers. For an example results as high as 75\% answering 5 if they liked the connection between the issue tracking system and the test results. 75\% also gave a 5 when asked about if they liked the way the test results were presented. The answers they gave about the implementation made it possible to conclude that it is possible to achieve a solution that can solve some of the presented problems. A better way to connect various tools to present and analyze the test results coming from multiple different sources.

Este trabalho apresenta a composição funcional (CF) como um novo paradigma para realização da síntese lógica de blocos combinacionais. CF usa uma abordagem ascendente para sintetizar funções Booleanas, sendo capaz de avaliar os custos das funções intermediárias e explorando dessa forma um grande número de combinações diferentes de funções candidatas. Há vantagens interessantes quando comparado à abordagem descendente da decomposição funcional. CF apresenta grande flexibilidade para criar algoritmos com resultados ótimos ou subótimos para diferentes aplicações. A estratégia proposta apresenta bons resultados para síntese de funções Booleanas visando diferentes tecnologias. CF é baseado nos seguintes princípios: (1) representação de funções lógicas como um par ligado com representações funcional e estrutural; (2) o algoritmo começa de um conjunto de funções iniciais; (3) funções mais simples são associadas para criar funções mais complexas; (4) existe uma ordem parcial que permite o uso da programação dinâmica; (5) um conjunto de funções permitidas pode ser mantido para reduzir o tempo de execução/consumo de memória. Este trabalho apresenta algoritmos de composição funcional para fatoração Booleana, incluindo fatoração ótima, fatoração considerando o operador OU-exclusivo, computação de cadeias mínimas de decisão e síntese de funções considerando somente portas lógicas majoritárias e inversores.
This work presents functional composition (FC) as a new paradigm for combinational logic synthesis. FC is a bottom-up approach to synthesize Boolean functions, being able to evaluate the cost of intermediate sub-functions, exploring a larger number of different candidate combinations. These are interesting advantages when compared to the top-down behavior of functional decomposition. FC presents great flexibility to implement algorithms with optimal or suboptimal results for different applications. The proposed strategy presents good results for the synthesis of Boolean functions targeting different technologies. FC is based on the following principles: (1) the representation of logic functions is done by a bonded pair of functional and structural representations; (2) the algorithm starts from a set of initial functions; (3) simpler functions are associated to create more complex ones; (4) there is a partial order, enabling dynamic programming; (5) a set of allowed functions can be used in order to reduce execution time/memory consumption. This work presents functional composition algorithms for Boolean factoring, including optimal factoring, Boolean factoring considering the exclusive-OR operator, minimum decision chain computation and synthesis of functions considering only majority and inverter logic gates.

The first part is a study of an ecological model with one herbivore and $N$ plants. The system has a new type of functional response due to the speculation that the plants compete with each other and have different levels of toxin which inhibit the herbivore's ability to eat up to a certain amount. We first derive the model mathematically and then investigate, both analytically and numerically, the possible dynamics for this model, including the bifurcation and chaos. We also discuss the conditions under which all the species can coexist. The second part is a study in the normal form theory. In particular, we study the relations between the normal forms and the first integrals in analytic vector fields. We are able to generalize one of Poincare's classical results on the nonexistence of first integrals in an autonomous system. Then in the space of 2n-dimensional analytic autonomous systems with exactly n resonances and n functionally independent first integrals, we obtain some results related to the convergence and generic divergence of the normalizations. Lastly we give a new proof of the necessary and sufficient conditions for a planar Hamiltonian system to have an isochronous center.

As a novel fluorescent material, carbon dots (CDs) demonstrate many excellent properties such as low toxicity, high stability and high resistance to photo bleaching. They are very likely to be applied in sensing, bio-imaging, photo catalysis and lighting devices, which require that the CDs can be tuneable in emission colours. Research to date have pointed to that the functional groups of CDs are very important to the emission of CDs, this MPhil work attempts to make some contributions to the understanding of how the functional groups affect the emission colour and the sensing selectivity. By reviewing many research papers, it is concluded that instead of size effect, the surface status related to the functional groups, specifically the O, N and S contents of the CDs, becomes the major factor of adjusting the emission colour of CDs. When the O, N or S contents are increased, red-shift of the fluorescence was observed in many studies. Apart from the colour tuning, the role of functional groups in the sensing applications of CDs is even more important. They act as the receptors which could recognise and capture the specific type of analyte, before the subsequent fluorescence quenching caused by aggregation or electron transfer (ET) process.
Thesis (Masters)
Master of Philosophy (MPhil)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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There has been an increasing demand of energy for socioeconomic activities and global population growth. Such gigantic amount of energy has been dominantly supplied with the consumption of fossil fuels that cannot be reliably generated in near future. This energy crisis has recently raised as a global issue that has attracted widespread attention. Abundant, renewable and environmentally friendly solar energy is one of the alternative energy sources to reduce the current dependence on traditional fossil fuels and help alleviate the environmental pollution. As such, photovoltaic devices, or solar cells, that convert solar energy into electricity have been explored intensively by academia and industries. Dye sensitized solar cells (DSSCs) have been proven to be one of the more economic, versatile and robust photovoltaic devices. However, the use of expensive, scarce novel metal, normally platinum or its alloys, as the counter electrode material has to a large extent been limiting the practical application of DSSCs. Thus there are urgent needs to develop low cost, earth abundant, high performance, chemical stable materials as the electrocatalysts for DSSCs. Metal oxides are one of the most abundant and stable substances on earth however they do not demonstrate high electrocatalytical activities as counter electrode materials. The aim of this thesis is to develop a generic approach to convert the wildly available metal oxide into high performance electrocatalyst as counter electrode materials for DSSCs. The thesis has been structured as followings to achieve the goals: in chapter 1, an overview on the photovoltaic devices and DSSCs has been presented. In particular, the research background on the counter electrode materials of DSSCs has been provided with a mini review of the electrode materials developed to date. In chapter 2, Co3O4 nanowires films have been fabricated as the starting materials and subsequently converted into sulphur doped (S-doped) Co3O4 using a vapour-phase hydrothermal (VPH) approach. The structure of Co3O4 film and VPH parameters have been optimized to achieve the best electrocatalytic performance that demonstrates significant improvement compare with the pristine Co3O4 film. In chapter 3, thin Co3O4 nanosheets film has been fabricated and converted in to S-Co3O4 film using VPH method. It has been demonstrated that an unprecedentedly high surface S content (>47%) has been achieved and the photovoltaic conversion efficiency of the DSSCs with such S-Co3O4 film was as superior as the one with benchmark Pt electrocatalysts. In chapter 4, the applicability of VPH method as a generic approach to convert metal oxides into electrocatalytic active materials has been investigated. Metal oxide films such as NiO and Fe2O3 have been successfully fabricated and modified with VPH treatment. The DSSCs equipped with such films as counter electrode have exhibited significantly improved solar to electricity conversion efficiency compared to those with equipped with pristine metal oxide film. Based on the findings in thesis, a conclusion has been provided in chapter 5 followed by a perspective on future research.
Thesis (Masters)
Master of Philosophy (MPhil)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text