Repeated evolution of heat responsiveness among Brassicaceae COPIA transposable elements

Eukaryotic genomes contain repetitive DNA sequences. This includes simple repeats and more complex transposable elements (TEs). Many TEs reach high copy numbers in the host genome, owing to their amplification abilities by specific mechanisms. There is growing evidence that TEs contribute to gene transcriptional regulation. However, excess of TE activity may lead to reduced genome stability. Therefore, TEs are suppressed by the transcriptional gene silencing machinery via specific chromatin modifications. In contrary, effectiveness of the epigenetic silencing mechanisms imposes risk for TE survival in the host genome. Therefore, TEs may have evolved specific strategies for bypassing epigenetic control and allowing the emergence of new TE copies. Recent studies suggested that the epigenetic silencing can be, at least transiently, attenuated by heat stress in A. thaliana. Heat stress induced strong transcriptional activation of COPIA78 family LTR-retrotransposons named ONSEN, and even their transposition in mutants deficient in siRNA-biogenesis. ONSEN transcriptional activation was facilitated by the presence of heat responsive elements (HREs) within the long terminal repeats, which serve as a binding platform for the HEAT SHOCK FACTORs (HSFs). This thesis focused on the evolution of ONSEN heat responsiveness in Brassicaceae. By using whole-transcriptome sequencing approach, multiple Arabidopsis lyrata ONSENs with conserved heat response were found and together with ONSENs from other Brassicaceae were used to reconstruct the evolution of ONSEN HREs. This indicated ancestral situation with two, in palindrome organized, HSF binding motifs. In the genera Arabidopsis and Ballantinia, a local duplication of this locus increased number of HSF binding motifs to four, forming a high-efficiency HRE. In addition, whole transcriptome analysis revealed novel heat-responsive TE families COPIA20, COPIA37 and HATE. Notably, HATE represents so far unknown COPIA family which occurs in several Brassicaceae species but is absent in A. thaliana. Putative HREs were identified within the LTRs of COPIA20, COPIA37 and HATE of A. lyrata, and could be preliminarily validated by transcriptional analysis upon heat induction in subsequent survey of Brassicaeae species. Subsequent phylogenetic analysis indicated a repeated evolution of heat responsiveness within Brassicaceae COPIA LTR-retrotransposons. This indicates that acquisition of heat responsiveness may represent a successful strategy for survival of TEs within the host genome.

Semi-automatic parallelisation of unstructured mesh codes

The availability of CFD software that can easily be used and produce high efficiency on a wide range of parallel computers is extremely limited. The investment and expertise required to parallelise a code can be enormous. In addition, the cost of supercomputers forces high utilisation to justify their purchase, requiring a wide range of software. To break this impasse, tools are urgently required to assist in the parallelisation process that dramatically reduce the parallelisation time but do not degrade the performance of the resulting parallel software. In this paper we discuss enhancements to the Computer Aided Parallelisation Tools (CAPTools) to assist in the parallelisation of complex unstructured mesh-based computational mechanics codes.

Partition alignment in three dimensional unstructured mesh multi-physics modelling

Unstructured mesh codes for modelling continuum physics phenomena have evolved to provide the facility to model complex interacting systems. Parallelisation of such codes using single Program Multi Data (SPMD) domain decomposition techniques implemented with message passing has been demonstrated to provide high parallel efficiency, scalability to large numbers of processors P and portability across a wide range of parallel platforms. High efficiency, especially for large P requires that load balance is achieved in each parallel loop. For a code in which loops span a variety of mesh entity types, for example, elements, faces and vertices, some compromise is required between load balance for each entity type and the quantity of inter-processor communication required to satisfy data dependence between processors.

Evaluación de vetiver (Chrysopogon zizanioides) y la elefanta (Pennisetum purpureum) en el diseño de humedales artificiales

En este trabajo se presenta la descripción e investigación en la evaluación de vetiver (Chrysopogon zizanioides) y la elefanta (Pennisetum purpureum) en el diseño de humedales artificiales. Para el tratamiento de aguas residuales de origen doméstico, siendo la vegetación uno de los principales componentes de estos sistemas de tratamientos no convencionales. Muchos \sistemas naturales" están siendo considerados con el propósito del tratamiento del agua residual y control de la contaminación del agua, debido a su alta fiabilidad ambiental y los bajos costos de construcción y mantenimiento, es el caso de los humedales artificiales. El interés en los sistemas naturales está basado en la conservación de los recursos asociados con estos sistemas como opuesto al proceso de tratamiento convencional de aguas residuales que es intensivo respecto al uso de energía y químicos. Los wetlands o humedales artificiales constituyen una alternativa de tratamiento debido a su alta eficiencia de remoción de contaminantes, a su bajo costo de instalación y mantenimiento y a su alta fiabilidad ambiental, generalmente un humedal artificial esta constituido por un medio de soporte el cual generalmente es arena o grava, vegetación y microorganismos o biopelícula los cuales llevan los diferentes procesos bioquímicos para remover los contaminantes del afluente. El objetivo general de este trabajo ha sido: Evaluar la eficiencia de remoción de materia orgánica, sólidos, nitrógeno y fósforo total de dos especies de plantas: vetiver (Chrysopogon zizanioides) y la elefanta (Pennisetum purpureum), en el diseño de humedales artificiales para el tratamiento de aguas residuales de origen doméstico. Los humedales artificiales o sistemas pilotos, se encuentran ubicados en la universidad de Medellín y reciben una preparación de agua sintética, que asemeja a las características de un agua residual de origen doméstico. En el presente trabajo se evalúa el porcentaje de remoción de la carga orgánica de aguas residuales, en un sistema de tratamiento por humedales artificiales con dos especies vegetales. El sistema fue diseñado con tres módulos instalados de manera adjunta. En el primero no se integra ninguna especie vegetal, solo el medio de sustrato el cual constituye el blanco (-), en el segundo se integraron organismos de la especie vetiver (Chrysopogon zizanioides), en el tercer sistema piloto, organismos de la especie elefanta (Pennisetum purpureum) y en el cuarto organismos de la especie papiro japones (Cyperus alternifolius), los cuales constituyen el control positivo (+). Los módulos experimentales fueron limpiados, cortados y adecuados acorde al montaje inicial de las plantas y al espacio requerido para su disposición. A cada sistema piloto se le agrega medio de soporte constituido por grava (5 a 10 cm) y arena (15 a 20 cm), el sustrato es evaluado y caracterizado por su diámetro nominal, posterior en cada sistema se siembran las especies en un área de 3x3 y cada humedal por dos semanas se adecua bajo la solución de Hoagland y Arnon y régimen de humedad. En el agua sintética se analizaron los siguientes parámetros: pH, sólidos totales, sólidos suspendido totales, sólidos disueltos totales, demanda química de oxígeno (DQO), demanda bioquímica de oxígeno (DBO5), nitrógeno total (NTK) y fosforo total (PT). También se realizó la determinación del crecimiento de las plantas a partir del incremento de biomasa, porosidad de la raíz y de igual forma se determina NTK y PT. Los resultados demostraron que el sistema es una opción para la remoción de la carga orgánica y de nutrientes en aguas residuales de origen doméstico, de bajo costo de operación y mantenimiento, especialmente se observa que las plantas que crecen en sistemas de régimen de humedad ácuico y ústico, tienden a tener una mayor recepción y adaptación en los humedales artificiales pilotos, es el caso de la elefanta (Pennisetum purpureum), el cual presenta las más altas tasas de remoción de contaminantes y nutrientes en el afluente, seguido por el papiro japonés (Cyperus alternifolius) y el vetiver (Chrysopogon zizanioides), respecto a tasas de remoción. La remoción de contaminantes que se presentan más altos respectivamente, constituyen sólidos en primera instancia, seguido por la demanda bioquímica de oxigeno (DBO5), demanda química de oxígeno (DQO), nitrógeno total (NTK) y fósforo total (PT), estos últimos presentan una baja tasa de remoción, debido a la naturaleza misma del contaminante, a los organismos que realizan la remoción y absorción y al tiempo de retención que se elige, el cual influye en la tasa de remoción del contaminante siendo menor en la concentración de fósforo, pero se encuentranen el rango esperado para estos sistemas de tratamiento no convencionales.

Impacto del liderazgo de género en los estilos de dirección de las organizaciones

La investigación tuvo como objetivo conocer los rasgos de personalidad predominantes en un grupo de líderes y de igual manera describir el impacto de sus estilos de liderazgo de acuerdo al género. Metodológicamente, fue una investigación cuantitativa, descriptiva y con un diseño no experimental. La población se conformó por líderes de empresas con presencia en la ciudad de Medellín. Por un muestreo de tipo intencional, se seleccionaron 20 líderes a quienes se les aplicó una encuesta estructurada de acuerdo a los objetivos de la investigación. La incorporación de mujeres a posiciones directivas se perfila como una vía útil para aprovechar los recursos humanos disponibles, en situación de igualdad de oportunidades, la diversidad de estilos y la variabilidad individual. En los últimos años, la investigación acerca de las relaciones entre género y estilos de liderazgo ha insistido en la idea de reivindicar el papel de la mujer y su contribución al desarrollo de las organizaciones. Los resultados de la investigación permiten afirmar que la extraversión constituye uno de los rasgos de personalidad distintivos de la muestra investigada y del liderazgo carismático; también se obtuvieron puntajes relevantes en apertura, rasgo distintivo del liderazgo transformacional. La alta efectividad representa la fortaleza más importante de la muestra, conjuntamente con la marcada conducta de entrenar, dirigir y delegar. Las relaciones encontradas entre las variables indican asociación significativa entre hombres y mujeres que lideran en las organizaciones.

Relations entre la composition du lait et les facteurs alimentaires dans les troupeaux laitiers québécois

L’objectif général des travaux présentes dans cette thèse de doctorat était d’établir la relation entre l’alimentation et la composition du lait des vaches laitières, en mettant l’emphase sur les teneurs en matières grasses (TMG), sur l’urée du lait et sur l’efficience d’utilisation de l’azote. Pour la TMG, c’est principalement la relation entre cette teneur et la différence alimentaire cations-anions (DACA) qui a été investiguée. Une base de données de 2 142 troupeaux québécois a été utilisée et la relation entre la composition de la ration, incluant la DACA, et la TMG du lait a été déterminée à l’aide de régressions multiples. Il a été possible de prédire entre 32 et 66 % de la variation de la TMG du lait en fonction du stade de lactation. Malgré plusieurs interactions trouvées, une augmentation de la DACA, une supplémentation avec de l’acide palmitique et une distribution des aliments en ration totale mélangée ont eu une relation positive avec la TMG du lait, tandis qu’une augmentation de la proportion de concentrés dans la ration a eu un effet négatif. Les modèles développés ont montré l’importance de la gestion de l’alimentation sur la TMG du lait. En plus, ils ont démontré l’intérêt de considérer la DACA dans la formulation de rations chez la vache laitière. Dans une deuxième étude, la même base des données a été utilisée pour identifier les facteurs nutritionnels qui peuvent faire varier la teneur en urée du lait. Contrairement à ce qui est mentionné dans la littérature, tant des corrélations positives et que négatives entre les teneurs en urée du lait et en protéines des rations à l’intérieur des troupeaux sur une période de 36 mois ont été obtenues. Pour mieux comprendre ces relations, les résultats de performances et d’alimentation de 100 troupeaux avec des corrélations positives (r > 0,69) et de 100 troupeaux avec des corrélations négatives (r < -0,44) entre la teneur en urée du lait et en protéine brute de la ration ont été comparés. Les résultats n’ont pas montré de différences entre les deux groupes ni pour la composition de la ration, ni pour l’urée du lait. Ces résultats ne permettent pas d’identifier le meilleur contexte pour l’utilisation de la teneur en urée du lait comme un outil de gestion de l’alimentation. Ces observations soulèvent des questions sur la validité de l’utilisation des statistiques d’alimentation provenant de la base de données utilisée pour des évaluations nutritionnelles plus spécifiques. Considérant les résultats du projet précédent, le dernier projet visait à mieux comprendre les caractéristiques des fermes avec différentes efficiences d’utilisation de l’azote en utilisant des données plus fiables. Ainsi, 100 fermes laitières au Québec ont été visitées pour recueillir les données de production, de consommation d’aliments et de gestion de leur troupeau. Ces fermes ont été divisées en quatre groupes par une analyse en grappes selon leur efficience d’utilisation de l’azote. La comparaison entre les groupes a montré que les fermes dans les groupes avec une plus haute efficience d’utilisation d’azote ont une production laitière moyenne par vache plus élevée. Pour les stratégies d’alimentation, les fermes plus efficientes donnent plus d’énergie, mais moins de protéines brutes que les fermes des groupes moins efficients. Les résultats ont également montré l’importance de la prise alimentaire des vaches sur l’efficience d’utilisation de l’azote puisque les fermes des groupes avec la plus grande efficience étaient également celles avec la plus faible prise alimentaire. Aussi, les résultats n’ont pas permis d’établir clairement la relation entre la teneur en urée du lait et l’efficience de l’utilisation de l’azote. En effet, des valeurs différentes pour l’urée du lait étaient obtenues entre le groupe plus efficient et le moins efficient, mais la faible ampleur de variation de l’efficience d’utilisation de l’azote des groupes intermédiaires n’a pas permis d’observer de différences pour l’urée du lait. Finalement, outre une réduction des risques de pollution, les fermes des groupes plus efficaces pour l’utilisation de l’azote étaient également celles avec la marge sur les coûts d’alimentation par les vaches plus élevées. Par conséquent, il y a aussi un intérêt économique à améliorer l’efficience de l’utilisation de l’azote sur les fermes.

O potencial energético do gradiente térmico na plataforma continental do sul do brasil

O crescimento da demanda energética, prevista para a metade do século XXI, com números embasados no crescimento demográfico e de consumo dos países em desenvol- vimento, sugere a busca por fontes energéticas renováveis e de menor impacto ao meio ambiente, conforme os tratados da política internacional. Portanto, o fornecimento de energia suplementar se torna vital nas sociedades modernas e sua extensão até o mar tem se constituído uma recente preocupação do ponto de vista enérgico e ecológico. Várias formas de conversão de energia foram desenvolvidas no decorrer dos anos, com destaque para a energia dos gradientes térmicos. A Plataforma Continental Sul do Bra- sil (PSCB) possui alta variabilidade espacial e temporal nos campos de temperatura, de forma que existe a necessidade de uma análise das regiões de maior potencial energético com respeito ao gradiente vertical de temperatura. Neste estudo, foram utilizados dados do modelo OCCAM com uma grade de resolu- ção horizontal de 0, 25o e resolução vertical de 66 níveis, distribuídos ao longo de um sistema de coordenadas vertical. Foram utilizadas imagens de temperatura superfícial do mar (TSM) obtidas a partir do sensor AVHRR (Advanced Very High Resolution Ra- diometer) de forma a realizar a validação dos dados do modelo OCCAM. A análise da média dos dados do modelo indicou um sítio energético de maior viabilidade devido oC ao padrão médio do gradiente térmico de aproximadamente 0, 17 ao longo da coluna vertical (545 m de profundidade) no oceano. Neste local, foram coletados os dados, e aplicados a um módulo de conversão de energia térmica dos oceanos que vem sendo desenvolvido na Universidade Federal do Rio Grande - FURG. A região de estudo de- monstrou possuir um local com ótimo potencial energético, onde a produção máxima de energia pode alcançar 111, 9MW , associada com um padrão variabilidade tempo- ral dominante de 12 meses. Este sítio energético demonstra maior eficiência durante o período de verão e outono ao longo dos anos e sua média para todo o período é de 94, 3MW . Neste estudo, duas correntes: Corrente do Brasil (CB) e a Contra Corrente Costeira (CCC), com águas de origem tropical e subantártica com aportes continentais, respecti- vamente, tem alta correlação com os valores dos gradientes térmicos e com os significa- tivos eventos de conversão energética. O sítio energético demonstrou alta estabilidade à sazonalidade e à gama de eventos meteorológicos e oceanográficos, de forma que pode ser qualificado como uma fonte suplementar a matriz energética do país para um futuro próximo.

POLYMER-NANOPARTICLE COMPOSITES FOR APPLICATIONS IN FLEXIBLE ELECTRONICS

The aim of this dissertation was to investigate flexible polymer-nanoparticle composites with unique magnetic and electrical properties. Toward this goal, two distinct projects were carried out. The first project explored the magneto-dielectric properties and morphology of flexible polymer-nanoparticle composites that possess high permeability (µ), high permittivity (ε) and minimal dielectric, and magnetic loss (tan δε, tan δµ). The main materials challenges were the synthesis of magnetic nanoparticle fillers displaying high saturation magnetization (Ms), limited coercivity, and their homogeneous dispersion in a polymeric matrix. Nanostructured magnetic fillers including polycrystalline iron core-shell nanoparticles, and constructively assembled superparamagnetic iron oxide nanoparticles were synthesized, and dispersed uniformly in an elastomer matrix to minimize conductive losses. The resulting composites have demonstrated promising permittivity (22.3), permeability (3), and sustained low dielectric (0.1), magnetic (0.4) loss for frequencies below 2 GHz. This study demonstrated nanocomposites with tunable magnetic resonance frequency, which can be used to develop compact and flexible radio frequency devices with high efficiency. The second project focused on fundamental research regarding methods for the design of highly conductive polymer-nanoparticle composites that can maintain high electrical conductivity under tensile strain exceeding 100%. We investigated a simple solution spraying method to fabricate stretchable conductors based on elastomeric block copolymer fibers and silver nanoparticles. Silver nanoparticles were assembled both in and around block copolymer fibers forming interconnected dual nanoparticle networks, resulting in both in-fiber conductive pathways and additional conductive pathways on the outer surface of the fibers. Stretchable composites with conductivity values reaching 9000 S/cm maintained 56% of their initial conductivity after 500 cycles at 100% strain. The developed manufacturing method in this research could pave the way towards direct deposition of flexible electronic devices on any shaped substrate. The electrical and electromechanical properties of these dual silver nanoparticle network composites make them promising materials for the future construction of stretchable circuitry for displays, solar cells, antennas, and strain and tactility sensors.

Design of advanced reverse osmosis and nanofiltration membranes for water purification

Most commercially available reverse osmosis (RO) and nanofiltration (NF) membranes are based on the thin film composite (TFC) aromatic polyamide membranes. However, they have several disadvantages including low resistance to fouling, low chemical and thermal stabilities and limited chlorine tolerance. To address these problems, advanced RO/NF membranes are being developed from polyimides for water and wastewater treatments. The following three projects have resulted from my research. (1) Positively charged and solvent resistant NF membranes. The use of solvent resistant membranes to facilitate small molecule separations has been a long standing industry goal of the chemical and pharmaceutical industries. We developed a solvent resistant membrane by chemically cross-linking of polyimide membrane using polyethylenimine. This membrane showed excellent stability in almost all organic solvents. In addition, this membrane was positively charged due to the amine groups remaining on the surface. As a result, high efficiency (> 95%) and selectivity for multivalent heavy metal removal was achieved. (2) Fouling resistant NF membranes. Antifouling membranes are highly desired for “all” applications because fouling will lead to higher energy demand, increase of cleaning and corresponding down time and reduced life-time of the membrane elements. For fouling prevention, we designed a new membrane system using a coating technique to modify membrane surface properties to avoid adsorption of foulants like humic acid. A layer of water-soluble polymer such as polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyvinyl sulfate (PVS) or sulfonated poly(ether ether ketone) (SPEEK), was adsorbed onto the surface of a positively charged membrane. The resultant membranes have a smooth and almost neutrally charged surface which showed better fouling resistance than both the positively charged NF membranes and commercially available negatively charged NTR-7450 membrane. In addition, these membranes showed high efficiency for removal of multivalent ions (> 95% for both cations and anions). Therefore, these antifouling surfaces can be potentially used for water softening, water desalination and wastewater treatment in a membrane bioreactor (MBR) process. (3) Thermally stable RO membranes. Commercial RO membranes cannot be used at temperature higher than 45°C due to the use of polysulfone substrate, which often limits their applications in industries. We successfully developed polyimides as the membrane substrate for thermally stable RO membranes due to their high thermal resistance. The polyimide-based composite polyamide membranes showed desalination performance comparable to the commercial TFC membrane. However, the key advantage of the polyimide-based membrane is its high thermal stability. As the feed temperature increased from 25oC to 95oC, the water flux increased 5 - 6 times while the salt rejection almost kept constant. This membrane appears to provide a unique solution for hot water desalination and also a feasible way to improve the water productivity by increasing the operating temperature without any drop in salt rejection.

Nonlinear distortion generation mechanisms in Doherty amplifiers

Nowadays, wireless communications systems demand for greater mobility and higher data rates. Moreover, the need for spectral efficiency requires the use of non-constant envelope modulation schemes. Hence, power amplifier designers have to build highly efficient, broadband and linear amplifiers. In order to fulfil these strict requirements, the practical Doherty amplifier seems to be the most promising technique. However, due to its complex operation, its nonlinear distortion generation mechanisms are not yet fully understood. Currently, only heuristic interpretations are being used to justify the observed phenomena. Therefore, the main objective of this work is to provide a model capable of describing the Doherty power amplifier nonlinear distortion generation mechanisms, allowing the optimization of its design according to linearity and efficiency criteria. Besides that, this approach will allow a bridge between two different worlds: power amplifier design and digital pre-distortion since the knowledge gathered from the Doherty operation will serve to select the most suitable pre-distortion models.

MICROSCALE DIELECTRIC ANTI-REFLECTION COATINGS FOR PHOTOVOLTAICS

In order to power our planet for the next century, clean energy technologies need to be developed and deployed. Photovoltaic solar cells, which convert sunlight into electricity, are a clear option; however, they currently supply 0.1% of the US electricity due to the relatively high cost per Watt of generation. Thus, our goal is to create more power from a photovoltaic device, while simultaneously reducing its price. To accomplish this goal, we are creating new high efficiency anti-reflection coatings that allow more of the incident sunlight to be converted to electricity, using simple and inexpensive coating techniques that enable reduced manufacturing costs. Traditional anti-reflection coatings (consisting of thin layers of non-absorbing materials) rely on the destructive interference of the reflected light, causing more light to enter the device and subsequently get absorbed. While these coatings are used on nearly all commercial cells, they are wavelength dependent and are deposited using expensive processes that require elevated temperatures, which increase production cost and can be detrimental to some temperature sensitive solar cell materials. We are developing two new classes of anti-reflection coatings (ARCs) based on textured dielectric materials: (i) a transparent, flexible paper technology that relies on optical scattering and reduced refractive index contrast between the air and semiconductor and (ii) silicon dioxide (SiO2) nanosphere arrays that rely on collective optical resonances. Both techniques improve solar cell absorption and ultimately yield high efficiency, low cost devices. For the transparent paper-based ARCs, we have recently shown that they improve solar cell efficiencies for all angles of incident illumination reducing the need for costly tracking of the sun’s position. For a GaAs solar cell, we achieved a 24% improvement in the power conversion efficiency using this simple coating. Because the transparent paper is made from an earth abundant material (wood pulp) using an easy, inexpensive and scalable process, this type of ARC is an excellent candidate for future solar technologies. The coatings based on arrays of dielectric nanospheres also show excellent potential for inexpensive, high efficiency solar cells. The fabrication process is based on a Meyer rod rolling technique, which can be performed at room-temperature and applied to mass production, yielding a scalable and inexpensive manufacturing process. The deposited monolayer of SiO2 nanospheres, having a diameter of 500 nm on a bare Si wafer, leads to a significant increase in light absorption and a higher expected current density based on initial simulations, on the order of 15-20%. With application on a Si solar cell containing a traditional anti-reflection coating (Si3N4 thin-film), an additional increase in the spectral current density is observed, 5% beyond what a typical commercial device would achieve. Due to the coupling between the spheres originated from Whispering Gallery Modes (WGMs) inside each nanosphere, the incident light is strongly coupled into the high-index absorbing material, leading to increased light absorption. Furthermore, the SiO2 nanospheres scatter and diffract light in such a way that both the optical and electrical properties of the device have little dependence on incident angle, eliminating the need for solar tracking. Because the layer can be made with an easy, inexpensive, and scalable process, this anti-reflection coating is also an excellent candidate for replacing conventional technologies relying on complicated and expensive processes.

Development of polymeric drug delivery vehicles for targeted cancer therapy

The aim of my Ph. D. thesis is to generalize a method for targeted anti-cancer drug delivery. Hydrophilic polymer-drug conjugates involve complicated synthesis; drug-encapsulated polymeric nanoparticles limit the loading capability of payloads. This thesis introduces the concept of nanoconjugates to overcome difficulties in synthesis and formulation. Drugs with hydroxyl group are able to initiate polyester synthesis in a regio- and chemo- selective way, with the mediation of ligand-tunable Zinc catalyst. Herein, three anti-cancer drugs are presented to demonstrate the high efficiency and selectivity in the method (Chapter 2-4). The obtained particles are stable in salt solution, releasing drugs over weeks in controlled manner. With the conjugation of aptamer, particles are capable to target prostate cancer cells in vitro. These results open the gateway to evaluate the in vivo efficacy of nanoconjugates for target cancer therapy (Chapter 5). Mechanism study of the polymerization leads to the discovery of chemosite selective synthesis of prodrugs with acrylate functional groups. Functional copolymer-drug conjugates will expand the scope of nanoconjugates (Chapter 6). Liposome-aptamer targeting drug delivery vehicle is well studied to achieve reversible cell-specific delivery of non-hydoxyl drugs e.g. cisplatin (Chapter 7). New monomers and polymerization mechanisms are explored for polyester in order to synthesize nanoconjugates with variety on properties (Chapter 8). Initial efforts to apply this type of prodrugs will be focused on the preparation of hydrogels for stem cell research (Chapter 9).

Projeto, implementação e análise de um conversor CC-CC de alto ganho e alto rendimento para aplicações fotovoltaicas

In recent years the photovoltaic generation has had greater insertion in the energy mix of the most developed countries, growing at annual rates of over 30%. The pressure for the reduction of pollutant emissions, diversification of the energy mix and the drop in prices are the main factors driving this growth. Grid tied systems plays an important role in alleviating the energy crisis and diversification of energy sources. Among the grid tied systems, building integrated photovoltaic systems suffers from partial shading of the photovoltaic modules and consequently the energy yield is reduced. In such cases, classical forms of modules connection do not produce good results and new techniques have been developed to increase the amount of energy produced by a set of modules. In the parallel connection technique of photovoltaic modules, a high voltage gain DC-DC converter is required, which is relatively complex to build with high efficiency. The current-fed isolated converters explored in this work have some desirable characteristics for this type of application, such as: low input current ripple and input voltage ripple, high voltage gain, galvanic isolation, feature high power capacity and it achieve soft switching in a wide operating range. This study presents contributions to the study of a high gain and high efficiency DC-DC converter for use in a parallel system of photovoltaic generation, being possible the use in a microinverter or with central inverter. The main contributions of this work are: analysis of the active clamping circuit operation proposing that the clamp capacitor connection must be done on the negative node of the power supply to reduce the input current ripple and thus reduce the filter requirements; use of a voltage doubler in the output rectifier to reduce the number of components and to extend the gain of the converter; detailed study of the converter components in order to raise the efficiency; obtaining the AC equivalent model and control system design. As a result, a DC-DC converter with high gain, high efficiency and without electrolytic capacitors in the power stage was developed. In the final part of this work the DC-DC converter operation connected to an inverter is presented. Besides, the DC bus controller is designed and are implemented two maximum power point tracking algorithms. Experimental results of full system operation connected to an emulator and subsequently to a real photovoltaic module are also given.

Effects of Information and Time of Use Pricing on Irish Electricity Demand and Supply

In this dissertation I quantify residential behavior response to interventions designed to reduce electricity demand at different periods of the day. In the first chapter, I examine the effect of information provision coupled with bimonthly billing, monthly billing, and in-home displays, as well as a time-of-use (TOU) pricing scheme to measure consumption over each month of the Irish Consumer Behavior Trial. I find that time-of-use pricing with real time usage information reduces electricity usage up to 8.7 percent during peak times at the start of the trial but the effect decays over the first three months and after three months the in-home display group is indistinguishable from the monthly treatment group. Monthly and bi-monthly billing treatments are not found to be statistically different from another. These findings suggest that increasing billing reports to the monthly level may be more cost effective for electricity generators who wish to decrease expenses and consumption, rather than providing in-home displays. In the following chapter, I examine the response of residential households after exposure to time of use tariffs at different hours of the day. I find that these treatments reduce electricity consumption during peak hours by almost four percent, significantly lowering demand. Within the model, I find evidence of overall conservation in electricity used. In addition, weekday peak reductions appear to carry over to the weekend when peak pricing is not present, suggesting changes in consumer habit. The final chapter of my dissertation imposes a system wide time of use plan to analyze the potential reduction in carbon emissions from load shifting based on the Ireland and Northern Single Electricity Market. I find that CO2 emissions savings are highest during the winter months when load demand is highest and dirtier power plants are scheduled to meet peak demand. TOU pricing allows for shifting in usage from peak usage to off peak usage and this shift in load can be met with cleaner and cheaper generated electricity from imports, high efficiency gas units, and hydro units.

Consideration of the relevance of standard quality techniques in Mass Customisation

The business philosophy of Mass Customisation (MC) implies rapid response to customer requests, high efficiency and limited cost overheads of customisation. Furthermore, it also implies the quality benefits of the mass production paradigm are guaranteed. However, traditional quality science in manufacturing is premised on volume production of uniform products rather than of differentiated products associated with MC. This creates quality challenges and raises questions over the suitability of standard quality engineering techniques. From an analysis of relevant MC and quality literature it is argued the aims of MC are aligned with contemporary thinking on quality and that quality concepts provide insights into MC. Quality issues are considered along three dimensions - product development, order fulfilment and customer interaction. The applicability and effectiveness of conventional quality engineering techniques are discussed and a framework is presented which identifies key issues with respect to quality for a spectrum of MC strategies.