Dissertations / Theses on the topic 'PBSA'

L’objectif premier de ce travail de thèse concerne la réalisation et la caractérisation de différents films multicouches afin d’étudier l’impact du phénomène de confinement des couches de polymères sur les propriétés barrières du polymère confiné et du film multicouche. Des films multicouches constitué de polycarbonate (PC) et de poly(m-xylène adipamide) (MXD6), polymères actuellement utilisés par les industries de l’emballage, ont tout d’abord été étudiés. Puis, dans un second temps, des films multicouches composés de polyesters biodégradables, à savoir des films multicouches d’acide polylactique (PLA) avec comme polymère confiné soit du poly(butylène succinate-co-butylène adipate) (PBSA) ou du poly(butylène succinate) (PBS), ont été élaborés.Une fois la structure multicouche obtenue et avoir confirmé l’amélioration de l’effet barrière grâce au phénomène de confinement, le deuxième objectif a été d’incorporer des charges lamellaires de type montmorillonite (Cloisite® 30B) dans la couche de polymère confiné dans le but d’accroitre davantage l’effet barrière du film multicouche sélectionné.Pour comprendre l’amélioration des propriétés barrières aux gaz et à l’eau des films multicouches élaborés, une analyse de la microstructure par DSC et DRX ainsi qu’une analyse des propriétés mécaniques ont été menées conjointement avec une observation par microscopie<br>The objective of the work was the elaboration and the characterization of different multilayer films in order to study the impact of the confinement effect of the polymer layers on the barrier properties. Multilayer films of polycarbonate (PC) and poly(m-xylene adipamide) (MXD6), which are usual polymers for packaging industries, have been studied. Then, multilayer films composed of biodegradable polyesters, such as polylactic acid (PLA) with poly(butylene succinate-co-butylene adipate) (PBSA) or poly(butylene succinate) (PBS) as the confined layers, have been prepared and characterized.For the multilayer structure presenting improved barrier performances due to the confinement effect, the second objective was to insert lamellar clays (Cloisite® 30B) into the confined polymer layers to again improve the barrier properties of the multilayer film. To understand the gas and water barrier improvement of the multilayer films, a microscopic observation of the films and an analysis of the microstructure by DSC and XRD have been performed with mechanical properties measurements

Joint Applied Project<br>Approved for public release; distribution is unlimited<br>The purpose of this project is to provide materials and information in the form of lessons that will make up a teachable course for graduate students of the Naval Post Graduate School. In addition, this research will address the current Department of Defense contracting policy, guidance, regulations and lessons learn. Performance-based Service Acquisition (PBSA) within the Department of Defense at both other government agencies, as well as commercial practices at progressive businesses are examined as they relate to PBSA. It is important to understand that the PBSA contract form involves acquisition strategies, methods, and techniques that define and communicate measurable performance expectations in terms of outcomes or results as opposed to directing performance methods, processes, systems or broad categories of work activity. To the maximum extent possible, the process should describe the work objectives in terms of what is to be the required output rather than how the work is to be accomplished and placing the responsibility for that accomplishment on the contractor. This document contains best practices that have proven useful for drafting statements of work, solicitations, and quality assurance plans, and in awarding and administering performance-based service acquisitions. This document is not intended to be mandatory regulatory guidance, such manuals already exist, but rather assistance to agencies and students in implementing performance-based service acquisition more fully throughout DOD.

O presente trabalho apresenta resultados do estudo que objetivou desenvolver blendas poliméricas compostas por dois polimeros biodegradáveis, o poli (butileno succinato - co - adipato) (PBSA) copolímero de poliésteres alifáticos e a policaprolactona (PCL). O estudo desenvolveu a tecnologia para a incorporação de nanowhiskers de celulose (NWC) enxertados com PCL (NWC - g - PCL), com objetivo de melhorar a adesão nanowhisker/matrix, e otimizar as propriedades mecânicas destes polímeros. As composições utilizadas foram 30PCL/70PBSA e 50PCL/50PBSA (em % de massa), com 1, 3 e 5% de NWC - g - PCL. As blendas e compósitos foram preparadas na forma de filmes por evaporação de solvente clorofórmio (casting) e via extrusão e moldagem por injeção, e caracterizadas quanto a suas propriedades térmicas, mecânicas e morfológicas através de calorimetria exploratória diferencial (DSC), análise termogravimétrica (TGA) e análise termodinâmica mecânica (DMTA), ensaio mecânico de tração e microscopia eletrônica de varredura (MEV). Os resultados obtidos através das análises de espectroscopia no infravermelho (IV) e difração de raios-X (DRX) sugerem a enxertia de cadeias de PCL nos NWC. Os polímeros puros, na forma de filmes, obtidos por evaporação de solvente, apresentaram estabilidade térmica semelhantes com início de decomposição em 290°C e decomposição máxima em torno de 420°C. Os filmes dos compósitos apresentaram uma diminuição da estabilidade térmica com o aumento dos teores de NWC - g - PCL nas formulações. As curvas DSC apresentaram dois picos de fusão e de cristalização o que indica a imiscibilidade dos polímeros, as análises térmicas dos filmes, mostraram também um aumento no grau de cristalinidade conforme os teores de nanowhiskers enxertados aumentaram, isso para composição 30/70. No caso dos compósitos com composição 50/50 (PCL/PBSA) houve uma diminuição do grau de cristalinidade dos polímeros. A imiscibilidade dos polímeros nos filmes foi confirmada também através das análises DMTA onde dois picos distintos de tan&#948; foram encontrados, para as composições 30/70, próximos das temperaturas de transição vítrea dos dois polímeros. As mesmas composições processadas via extrusão, e corpos de prova moldados por injeção, apresentaram uma queda na estabilidade térmica detectada pelas análises TGA. Houve um aumento no grau de cristalinidade da PCL conforme maior quantidade de nanowhisker nos compósitos. A maior rigidez do material foi confirmada a partir dos ensaios mecânicos de tração, onde o módulo elástico aumentou aproximadamente duas vezes com o aumento da porcentagem de nanocargas nos compósitos, assim como a diminuição da porcentagem de alongamento e a resistência à tração não sofreu grandes alterações.<br>In this dissertation results of the study aimed to develop polymer blends composed of two biodegradable polymers, poly (butylene succinate - co - adipate) (PBSA) and aliphatic polyester polycaprolactone (PCL). The study developed the technology for the incorporation of cellulose nanowhiskers (NWC) grafted PCL (NWC - g - PCL), aiming to improve adherence nanowhisker / matrix, and improve mechanical properties of these polymers. The compositions used were 30PCL/70PBSA and 50PCL/50PBSA (in mass%), with 1, 3 and 5% of NWC - g - PCL. The blends and composites were prepared as films by evaporation of solvent chloroform (casting) and via extrusion and injection molding, and characterized their thermal, mechanical and morphological means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) mechanical and thermodynamic analysis (DMTA), mechanical tests and scanning electron microscopy (SEM). The results obtained by analysis of infrared spectroscopy (IR) and X -ray diffraction (XRD) suggest the grafting of PCL chains in the NWC. The pure polymers in the form of films obtained by solvent evaporation, showed similar thermal stability with decomposition onset at 290°C and decomposition maximum at around 420°C. The films of the composites showed a decrease in thermal stability with increased levels NWC - g - PCL in the formulations. The DSC curves show two melting peaks and crystallization which indicates immiscibility of the polymers, the thermal analysis of the film showed also an increase in degree of crystallinity as the content of grafted nanowhiskers increased, this composition to 30/70. In the case of composites with composition 50/50 (PCL / PBSA) there was a decrease in the degree of crystallinity of polymers. The immiscibility of the polymers in the film was also confirmed by analysis DMTA where tan&#948; two distinct peaks were found for compositions 30/70, close to the glass transition temperatures of the two polymers. The same compositions processed via extrusion, and specimens injection molded, showed a decrease in thermal stability detected by TGA analysis. There was an increase in the degree of crystallinity of the PCL as the largest quantity of nanowhisker composites. The rigidity of the material was confirmed from the tensile test, where the elastic modulus increased approximately twice the percentage increase of nanofiller in the composites, as well as the decrease in percentage elongation and tensile strength has not changed much.

Thesis (M.S. in Contract Management)--Naval Postgraduate School, September 2003.<br>Thesis advisor(s): Jeffrey Cuskey, David Krueger. Includes bibliographical references (p. 89-91). Also available online.

Uma das alternativas para elaboração de filmes biodegradáveis é a blenda de poliésteres alifáticos sintéticos biodegradáveis, que ainda tem um custo elevado, com agropolímeros, como o amido, de mais baixo custo. O objetivo do trabalho foi a elaboração e caracterização de filmes flexíveis a base de amido termoplástico (ATP) e polibutileno succinato co-adipato (PBSA) por meio do processo de extrusão sopro de filme tubular. O ATP usado consistiu de três formulações: amido de mandioca/glicerol, amido de mandioca/amido de milho com alto teor de amilose/amido de milho hidroxipropilado/glicerol/gelatina e amido de mandioca/amido de milho com alto teor de amilose/glicerol, que foram misturadas com o PBSA nas proporções: ATP:PBSA (0:100), (30:70) e (70:30). Os filmes foram caracterizados quanto às propriedades mecânicas, térmicas, de barreira, ópticas e microestruturais, cristalinidade, espectroscopia de infravermelho com transformada de Fourier (FTIR) e goniometria. Os filmes de ATP:PBSA apresentaram-se opacos e com coloração creme, enquanto que os filmes de PBSA puro eram transparentes. Filmes com altas concentrações de ATP (70%) apresentaram menor cristalinidade e propriedades mecânicas inferiores em relação às do filme de PBSA puro. Filmes com 30% de ATP contendo amido com alto teor de amilose apresentaram-se com boas propriedades mecânicas (até 330% de elongação) e de barreira (< 3,40 x 10-6 g.m-1.dia-1.Pa-1). As análises de FTIR e de calorimetria diferencial de varredura permitiram observar que não houve alterações importantes nas ligações químicas e nas transições térmicas dos filmes, indicando que o ATP e o PBSA usados neste trabalho são pouco miscíveis. Entretanto, mesmo com esta baixa miscibilidade e altas concentrações de ATP (70%), a blenda ATP:PBSA permitiu a formação de filmes tubulares por extrusão, o que não é possível apenas com ATP, em função das altas exigências específicas deste processo em relação a maquinabilidade do material.<br>Blending high cost biodegradable synthetic aliphatic polyesters with low cost agropolymers, such as starch, is one of the alternatives for the production of biodegradable films. The objective of this work was to develop and characterize a biodegradable film based on thermoplastic starch (TPS) and polybutylene succinate co-adipate (PBSA), by film blow extrusion. TPS consisted on three different formulations: manioc starch/glycerol, manioc starch/high amylose corn starch/glycerol and manioc starch/high amylose corn starch/hydroxypropylated corn starch/glycerol, which were blended with PBSA in the following proportions: TPS:PBSA (0:100), (30:70) and (70:30). The films were characterized by mechanical, barrier, thermal, optical and microstructural properties, crystallinity, FTIR spectroscopy and goniometry. TPS:PBSA films were opaque showing a cream coloration, whereas pure PBSA films were translucent. Films with 70% TPS showed low crystallinity and poor mechanical properties compared to pure PBSA films. Films containing 30% TPS with high amylose starch showed good mechanical (up to 330% elongation) and barrier (< 3,40 x 10-6 g.m-1.day-1.Pa-1) properties. Thermal transitions and chemical bonds of TPS:PBSA films showed no considerable changes as indicated by FTIR and DSC analyses, due to low miscibility of the TPS and PBSA polymers. Nevertheless, even with low miscibility and high TPS concentrations (70%), it was possible to film blow TPS:PBSA blends, whereas this is not possible with plain TPS polymers, due to the high and specific processability characteristics necessary for using this technique.

The purpose of this MBA professional report is to study and analyze Performance-Based Service Acquisition (PBSA) policies and processes within Department of Defense (DoD) for potential applicability to Hellenic Navy service acquisition polices. This MBA Report includes a literature review and background information about PBSA, current PBSA implementation within the U.S. DoD, current Hellenic Navy acquisition laws and regulations, the legal barriers and constraints to implementation of PBSA and recommendations (based on the findings) to the Hellenic Navy for the potential implementation of PBSA.

La thèse porte sur l’étude des 2 premières enzymes de la voie du MEP: la DXS et DXR. La voie du MEP conduit à la biosynthèse des isoprénoïdes chez la plupart des bactéries, dont des pathogènes. Etant absente chez l’homme, les enzymes de cette voie cible idéale pour la recherche de nouveaux antimicrobiens. L’objectif principal était d’améliorer le développement de nouveaux antimicrobiens. Nous avons utilisé des outils computationnels : méthodes de docking et de mécanique moléculaire couplée à la méthode MM/PBSA. Nous avons identifié les résidus contribuant significativement à la fixation d’un ligand dans le site actif de la DXR. Ces résultats ont été utilisés lors de la conception de nouveaux candidats inhibiteurs de type bisubstrat, biligand et difluoro phosphonate, dont 2 ont pu être synthétisés. Nous avons également développé une méthode de synthèse donnant accès au L- et D-GAP énantiomeriquement purs, dans le but d’étudier l’énantiospécificité de la DXS face à son substrat D-GAP<br>This thesis concerns the study of the 2 first enzymes of the MEP pathway: DXS and DXR. The MEP pathway permits the biosynthesis of isoprénoïdes in most bacteria, including pathogenic one. As it is not present in human, enzymes of MEP pathway are effective targets in the research of new antimicrobial drugs. The objective was to advance the development of new antimicrobiotic compounds. We used computational tools: molecular docking and molecular dynamics simulations coupled with an MM/PBSA approach. We were able to identify residues that contribute significantly to the ligand binding in the DXR active site. These results were used to guide the conception of new inhibitor models, such as bisubstrates, biligands and α,α-difluoro phosphonates, two of which were synthetized. We also developed a synthesis method to obtain L- and D-GAP as enantiomerically pure molecules. The goal was to study the enantiospecificity of DXS to its substrate, D-GAP

Dans le but de développer des matériaux actifs antimicrobiens biodégradables à libération contrôlée, des mélanges de deux polymères biodégradables incompatibles ont été mis en oeuvre par les voies classiques de transformation des matériaux plastiques (extrusion). L'originalité de ces mélanges réside dans la recherche d'une stratégie de contrôle de la libération d'espèces actives incorporées dans l'une des phases du système et générée par la tortuosité/disponibilité de chemins de diffusion sélectifs obtenue en jouant sur les proportions relatives des 2 polymères en présence. Les systèmes binaires étudiés sont : [amidon de maïs plastifié, PLS et poly(butylène succinate-co-adipate) ou PBSA] et un système référence [(poly(oxyethylène) PEO et PBSA]. Dans ces mélanges, les polymères polaires (PLS ou PEO) jouent le rôle de matrice hôte pour solubiliser les migrants actifs ou modèles, souvent polaires et le polymère semipolaire,le PBSA, compense la faiblesse des propriétés mécaniques et barrières à l'eau de la phase amylacée et /ou hydrophile tout en présentant une température de fusion basse (85°C) compatible avec une stratégie à plus long terme d'incorporation d'actifs peu thermostables. Les systèmes obtenus sont caractérisés afin de corréler les différentes morphologies obtenues en jouant sur la composition des mélanges (phase dispersées dans une matrice continue, ou continuité partielle ou totale, systèmes pseudo-multicouches) aux phénomènes de transport de diverses molécules. Les caractérisations effectuées ont alors pour objectif d'élucider les morphologies obtenues par i) extraction sélective par voie solvant (ou hydrolyse) enrichie par des observations microscopiques ii) par utilisation de sondes gazeuses via les propriétés de transport de vapeur d'eau (qui privilégiera les chemins offerts par la matrice polaire) ou de l'oxygène (qui, lui, privilégiera les chemins de diffusions offerts par le PBSA) iii) par la réalisation des isothermes et cinétiques de sorption d'eau et enfin iv) par l'étude de la libération dans l'eau de migrants actifs ou modèles préalablement incorporés dans la phase polaire (fluorescéinate de sodium, acides organiques, glycine, di-glycine). Il a ainsi pu être montré pour les mélanges PLS/PBSA que les phénomènes de diffusion sont contrôlés par la tortuosité générée par la présence de PBSA dans le cas du relargage de la fluorescéine et par l'hydratation limitée de la phase polaire en présence de fortes teneurs en PBSA dans le mélange pour les phénomènes de sorption d'eau. Ainsi, la diffusion de la fluorescéine, par exemple, est nettement plus influencée que celle de l'eau par la tortuosité (elle-même gouvernée par la composition du mélange), très probablement en raison de sa plus grande masse moléculaire. Pour les mélanges PEO/PBSA, des comportements distincts ont été mis en évidence selon la composition des mélanges. Pour les mélanges à faibles teneurs ou teneurs intermédiaires en PBSA, un transport rapide se produit principalement via la dissolution du PEO. La morphologie ne semble pas influencer les cinétiques de libération. Pour des teneurs élevées en PBSA, la cinétique de libération est cette fois dépendante de la morphologie présente un temps de latence caractéristique d'une cinétique de perméation (libération proportionnelle au temps). En conclusion, les matériaux élaborés par les voies migrants polaires tels que des conservateurs pour élaborer par exemple des emballages actifs antimicrobiens<br>In order to develop biodegradable and active materials s, blends of two incompatible biodegradable polymers have been implemented by conventiona plastic material processing (extrusion). The originality of these blends lies in the search for a strategy to control the release of active species included in one of the phases of the system. Therefore, the tortuosity / availability of selective diffusion paths obtained by varying the relative proportions of the two polymers involved will be exploited. Studied binary systems consist of: [plasticized corn starch, PLS and poly (butylene succinate-co-adipate) or PBSA] and a reference system [(poly (oxyethylene) PEO and PBSA]. In these blends, polar polymers (PLS or PEO) play the role of host matrix to solubilize the active migrants or model molecules which are often polar, and the semi-polar polymer (PBSA) compensates for the weakness of the mechanical properties of the starchy and / or hydrophilic phase while having a low melting temperature (85 ° C) consistent with a longer-term strategy of incorporation of thermostable active molecules such as lysozyme or nisin. The resulting systems were characterized to correlate the different morphologies obtained by varying the composition of the blends (dispersed phase in a continuous matrix, partial or total continuity, or pseudo-layer systems) to the transport phenomena of various molecules. The performed characterizations aim to elucidate the morphologies by i) selective solvent extraction method (or hydrolysis) enriched by microscopical observations ii) using gaseous probes via the determination of water vapor transport properties (water will favor the paths provided by the polar matrix) or oxygen transport properties (O2 will favor the diffusion paths provided by the PBSA matrix) iii) by determining water sorption isotherms and kinetics and finally iv) by the study of the release in water of active or model migrants previously incorporated in the polar phase (sodium fluoresceinate, organic acids, glycine, diglycine). It has been observed that the diffusion phenomena in PLS / PBSA blends are controlled by the tortuosity generated by the presence of PBS and by the limited hydration of the polar phase at high PBSA contents in the blends for water sorption phenomena. Thus, the diffusion of fluorescein, for example, is much more influenced by the tortuosity (itself governed by the composition of the blends) than that of water, which is likely due to its higher molecular weight. For PEO / PBSA blends, distinct behaviors were observed according to the blends composition. For the blends with low or intermediate content of PBSA, rapid transport occurs mainly via the dissolution of the PEO. The morphology did not seem to influence the release kinetics. For high contents of PBSA, the release kinetics were dependent on the morphology and a time lag which is characteristic of permeation kinetics (release proportional to time) appeared. In conclusion, the multiphasic materials prepared by plastic processing look promising for the controlled release of polar migrants such as food preservatives to develop antimicrobial active packaging

Molecular recognition is essential to all biological interactions and processes. Knowledge of the structural basis of recognition offers a powerful mechanism for understanding, predicting and controlling the behaviour of biological systems. In this thesis, we present, firstly a computational and crystallographic analysis of molecular recognition in protein-ligand systems; and secondly, progress towards the synthesis of a fluorescent probe for calcium ion recognition. Class I phosphoinositide 3-kinases (PI3Ks), in particular PI3Kγ, have long been considered promising drug targets for the treatment of inflammatory and autoimmune disorders. As a step towards improved understanding of PI3K binding preferences, we examine the basis on which PI3Kγ distinguishes γ-selective inhibitors AS-605240 and AS-604850, with a ~30-fold preference for the former. Interestingly, despite the chemical similarity of the two ligands, the X-ray structures for their PI3Kγ complexes exhibit the molecules in different conformers, s-cis for AS-604850 and s-trans for AS-605240. Here, we re-examine the PI3Kγ/AS-605240 crystallographic data and find that not only is a s-cis conformation possible but in fact it has a much higher occupancy (87%) than the originally modelled s-trans isomer (13%). Subsequently, to account for the isomeric complexities presented by the ligands, we perform 140 ns MD simulations of the four PI3Kγ complexes in explicit solvent: this reveals similar conformational flexibility at the active site for all systems. Yet, the conformations sampled by the s-cis isomers are more consistent with the conformations reported by the X-ray crystal structures. Subsequent energetic analysis was performed incorporating ensemble-averaging and desolvation effects via the Poisson-Boltzmann continuum solvent model. For both inhibitors the s-cis isomers are predicted to be the most favourable conformations. Additionally, the results indicate a preference for AS-605240, as observed experimentally. The molecular basis for this preference is discussed, together with a comparison of molecular mechanical and quantum chemical treatments of the key ligand-Val882 interaction. This study provides structural, dynamical and energetic insights into the subtle basis of molecular recognition by PI3Kγ.Fluorescent probes have evolved into an extremely useful tool for the detection of calcium in biological systems. Benzothiazole derivatives BTC, and its iminocoumarin analogue BTIC, are two low affinity calcium indicators featuring many desirable properties for cellular calcium measurement. In an effort to produce fluorophores that can be chemically conjugated with a screening protein, such as Green Fluorescent Protein (GFP), we aimed to derivatise BTC and BTIC. Two synthetic approaches towards the synthesis of these potential fluorescent probes are outlined.

Orientador: Gaston Eduardo Barberis<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin<br>Made available in DSpace on 2018-07-19T12:09:06Z (GMT). No. of bitstreams: 1 ValdiviaLeon_JoseArturo_M.pdf: 1197413 bytes, checksum: 6e8b1e092f41a6caf14f26d982c90614 (MD5) Previous issue date: 1994<br>Resumo: Este trabalho apresenta a estrutura de bandas e a densidade de estados eletrônicos para os sais de chumbo PbTe, PbS e PbSe, usando o método de Combinação Linear de Orbitais Atômicos parametrizado de Slater e Koster com a base de Vogl sp3s*. O cálculo é feito considerando-se apenas primeiros vizinhos e o hamiltoniano relativista de Pauli. Os resultados mostram que com este simples modelo, que gera uma matriz 20 x 20 e treze parâmetros ajustáveis, é possível reproduzir aceitavelmente as bandas de valência e as primeiras bandas de condução obtidas por cálculos relativistas de Psudopotenciais Empírico local<br>Abstract: We present here the band structure and the density of states of the lead salts PbTe, PbS and PbSe, resulting from the parametrized Linear Combination of Atomic Orbitals method of Slater and Koster, with the Vogl base Sp3S.; by considering first neighbors and the Pauli's relativistic hamiltonian. Our results show that with this simple model, a 20 x 20 matrix and thirteen adjustable parameters, we can acceptly reproduce the valence and the first conduction bands ca1culated by relativistic local Empirical Pseudopotential Method<br>Mestrado<br>Física<br>Mestre em Física

Nanocrystal quantum dots (NQDs) show great promise in the advancement of the field of photovoltaics. While the maximum efficiency of conventional solar cell (SC) devices is limited to ∼ 31% (Shockley-Queisser limit), devices based on NQDs may attain a maximal thermodynamic efficiency of 42% through the exploitation of multiple exciton generation (MEG). In this process, several electron- hole pairs are created by the absorption of a single high energy photon, as opposed to the single excitons created in conventional solar cell devices. IV-VI semiconductor nanocrystals (PbS, PbSe) are of particular interest as candidates for the exploitation of MEG due to the narrow band gap, high confinement energies, and long radiative carrier lifetimes observed in these systems. In order to realise the full potential of MEG devices, full characterisation of the optoelectronic properties of the underlying nanoparticles is desirable. While the size-dependent properties of NQDs are well understood, the effects of NQD shape are less so. This thesis investigates the effect of ellipticity on the optoelectronic properties associated with spheroidal NQDs. To this end, a four-band, anisotropic, and radially variant k · p system Hamiltonian is expanded in a planewave basis in order to calculate single-particle eigenenergies and eigenfunctions of colloidal PbSe/PbS core/shell heterogeneous NQDs of varying ellipticity. Many-body effects are accounted for via a full configuration interaction (CI) Hamiltonian, the basis of which is comprised of the single-particle states. Exci- tonic and bi-excitonic corrections are then found by mixing of the basis states. In this manner, such diverse electronic and optical properties as quasi-particle binding energies, momentum matrix elements, and charge carrier lifetimes, both radiative and non-radiative, may be predicted.

Proteins have an indispensable role in the cell. They carry out a wide variety of structural, catalytic and signaling functions in all known biological systems. To perform their biological functions, proteins establish interactions with other bioorganic molecules including other proteins. Therefore, protein-protein interactions is one of the central topics in molecular biology. My thesis is devoted to three different topics in the field of protein-protein interactions. The first one focuses on solvent contribution to protein interfaces as it is an important component of protein complexes. The second topic discloses the structural and functional potential of fluorine's unique properties, which are attractive for protein design and engineering not feasible within the scope of canonical amino acids. The last part of this thesis is a study of the impact of charged amino acid residues within the hydrophobic interface of a coiled-coil system, which is one of the well-established model systems for protein-protein interactions studies. I. The majority of proteins interact in vivo in solution, thus studies of solvent impact on protein-protein interactions could be crucial for understanding many processes in the cell. However, though solvent is known to be very important for protein-protein interactions in terms of structure, dynamics and energetics, its effects are often disregarded in computational studies because a detailed solvent description requires complex and computationally demanding approaches. As a consequence, many protein residues, which establish water-mediated interactions, are neither considered in an interface definition. In the previous work carried out in our group the protein interfaces database (SCOWLP) has been developed. This database takes into account interfacial solvent and based on this classifies all interfacial protein residues of the PDB into three classes based on their interacting properties: dry (direct interaction), dual (direct and water-mediated interactions), and wet spots (residues interacting only through one water molecule). To define an interaction SCOWLP considers a donor–acceptor distance for hydrogen bonds of 3.2 Å, for salt bridges of 4 Å, and for van der Waals contacts the sum of the van der Waals radii of the interacting atoms. In previous studies of the group, statistical analysis of a non-redundant protein structure dataset showed that 40.1% of the interfacial residues participate in water-mediated interactions, and that 14.5% of the total residues in interfaces are wet spots. Moreover, wet spots have been shown to display similar characteristics to residues contacting water molecules in cores or cavities of proteins. The goals of this part of the thesis were: 1. to characterize the impact of solvent in protein-protein interactions 2. to elucidate possible effects of solvent inclusion into the correlated mutations approach for protein contacts prediction To study solvent impact on protein interfaces a molecular dynamics (MD) approach has been used. This part of the work is elaborated in section 2.1 of this thesis. We have characterized properties of water-mediated protein interactions at residue and solvent level. For this purpose, an MD analysis of 17 representative complexes from SH3 and immunoglobulin protein families has been performed. We have shown that the interfacial residues interacting through a single water molecule (wet spots) are energetically and dynamically very similar to other interfacial residues. At the same time, water molecules mediating protein interactions have been found to be significantly less mobile than surface solvent in terms of residence time. Calculated free energies indicate that these water molecules should significantly affect formation and stability of a protein-protein complex. The results obtained in this part of the work also suggest that water molecules in protein interfaces contribute to the conservation of protein interactions by allowing more sequence variability in the interacting partners, which has important implications for the use of the correlated mutations concept in protein interactions studies. This concept is based on the assumption that interacting protein residues co-evolve, so that a mutation in one of the interacting counterparts is compensated by a mutation in the other. The study presented in section 2.2 has been carried out to prove that an explicit introduction of solvent into the correlated mutations concept indeed yields qualitative improvement of existing approaches. For this, we have used the data on interfacial solvent obtained from the SCOWLP database (the whole PDB) to construct a “wet” similarity matrix. This matrix has been used for prediction of protein contacts together with a well-established “dry” matrix. We have analyzed two datasets containing 50 domains and 10 domain pairs, and have compared the results obtained by using several combinations of both “dry” and “wet” matrices. We have found that for predictions for both intra- and interdomain contacts the introduction of a combination of a “dry” and a “wet” similarity matrix improves the predictions in comparison to the “dry” one alone. Our analysis opens up the idea that the consideration of water may have an impact on the improvement of the contact predictions obtained by correlated mutations approaches. There are two principally novel aspects in this study in the context of the used correlated mutations methodology : i) the first introduction of solvent explicitly into the correlated mutations approach; ii) the use of the definition of protein-protein interfaces, which is essentially different from many other works in the field because of taking into account physico-chemical properties of amino acids and not being exclusively based on distance cut-offs. II. The second part of the thesis is focused on properties of fluorinated amino acids in protein environments. In general, non-canonical amino acids with newly designed side-chain functionalities are powerful tools that can be used to improve structural, catalytic, kinetic and thermodynamic properties of peptides and proteins, which otherwise are not feasible within the use of canonical amino acids. In this context fluorinated amino acids have increasingly gained in importance in protein chemistry because of fluorine's unique properties: high electronegativity and a small atomic size. Despite the wide use of fluorine in drug design, properties of fluorine in protein environments have not been yet extensively studied. The aims of this part of the dissertation were: 1. to analyze the basic properties of fluorinated amino acids such as electrostatic and geometric characteristics, hydrogen bonding abilities, hydration properties and conformational preferences (section 3.1) 2. to describe the behavior of fluorinated amino acids in systems emulating protein environments (section 3.2, section 3.3) First, to characterize fluorinated amino acids side chains we have used fluorinated ethane derivatives as their simplified models and applied a quantum mechanics approach. Properties such as charge distribution, dipole moments, volumes and size of the fluoromethylated groups within the model have been characterized. Hydrogen bonding properties of these groups have been compared with the groups typically presented in natural protein environments. We have shown that hydrogen and fluorine atoms within these fluoromethylated groups are weak hydrogen bond donors and acceptors. Nevertheless they should not be disregarded for applications in protein engineering. Then, we have implemented four fluorinated L-amino acids for the AMBER force field and characterized their conformational and hydration properties at the MD level. We have found that hydrophobicity of fluorinated side chains grows with the number of fluorine atoms and could be explained in terms of high electronegativity of fluorine atoms and spacial demand of fluorinated side-chains. These data on hydration agrees with the results obtained in the experimental work performed by our collaborators. We have rationally engineered systems that allow us to study fluorine properties and extract results that could be extrapolated to proteins. For this, we have emulated protein environments by introducing fluorinated amino acids into a parallel coiled-coil and enzyme-ligand chymotrypsin systems. The results on fluorination effect on coiled-coil dimerization and substrate affinities in the chymotrypsin active site obtained by MD, molecular docking and free energy calculations are in strong agreement with experimental data obtained by our collaborators. In particular, we have shown that fluorine content and position of fluorination can considerably change the polarity and steric properties of an amino acid side chain and, thus, can influence the properties that a fluorinated amino acid reveals within a native protein environment. III. Coiled-coils typically consist of two to five right-handed α-helices that wrap around each other to form a left-handed superhelix. The interface of two α-helices is usually represented by hydrophobic residues. However, the analysis of protein databases revealed that in natural occurring proteins up to 20% of these positions are populated by polar and charged residues. The impact of these residues on stability of coiled-coil system is not clear. MD simulations together with free energy calculations have been utilized to estimate favourable interaction partners for uncommon amino acids within the hydrophobic core of coiled-coils (Chapter 4). Based on these data, the best hits among binding partners for one strand of a coiled-coil bearing a charged amino acid in a central hydrophobic core position have been selected. Computational data have been in agreement with the results obtained by our collaborators, who applied phage display technology and CD spectroscopy. This combination of theoretical and experimental approaches allowed to get a deeper insight into the stability of the coiled-coil system. To conclude, this thesis widens existing concepts of protein structural biology in three areas of its current importance. We expand on the role of solvent in protein interfaces, which contributes to the knowledge of physico-chemical properties underlying protein-protein interactions. We develop a deeper insight into the understanding of the fluorine's impact upon its introduction into protein environments, which may assist in exploiting the full potential of fluorine's unique properties for applications in the field of protein engineering and drug design. Finally we investigate the mechanisms underlying coiled-coil system folding. The results presented in the thesis are of definite importance for possible applications (e.g. introduction of solvent explicitly into the scoring function) into protein folding, docking and rational design methods. The dissertation consists of four chapters: ● Chapter 1 contains an introduction to the topic of protein-protein interactions including basic concepts and an overview of the present state of research in the field. ● Chapter 2 focuses on the studies of the role of solvent in protein interfaces. ● Chapter 3 is devoted to the work on fluorinated amino acids in protein environments. ● Chapter 4 describes the study of coiled-coils folding properties. The experimental parts presented in Chapters 3 and 4 of this thesis have been performed by our collaborators at FU Berlin. Sections 2.1, 2.2, 3.1, 3.2 and Chapter 4 have been submitted/published in peer-reviewed international journals. Their organization follows a standard research article structure: Abstract, Introduction, Methodology, Results and discussion, and Conclusions. Section 3.3, though not published yet, is also organized in the same way. The literature references are summed up together at the end of the thesis to avoid redundancy within different chapters.

The purpose of this thesis is to outline the research undertaken into the synthesis of metal chalcogenide nanomaterials followed by their behavior of in diverse thermodynamic conditions. This thesis will focus on the research of novel routes to metal chalcogenides, especially CdS, PbS and PbSe. An effort was made in order to improve existing techniques by combining knowledge from diverse fields. Instabilities in nanoparticles and related behaviors, e.g. tendency to grow in specific shapes, aggregate and coalesce, were the other focusing point of this thesis. This thesis is divided into five main chapters. The first chapter introduces nanomaterials and their potential applications. An emphasis is made on the synthetic techniques to nanomaterials and their properties. Chapter two describes the synthetic approaches that were investigated during this work. Soft-hydrothermal and microwave-assisted hydrothermal routes to nanoparticles will be described. Chapter three focuses on the formation of stable nano-shapes different than the bulk-shape for PbS and PbSe nanocrystals. Their ability to self-organise on an amorphous substrate is also presented. Chapter four describes the research undertaken by transmission electron microscopy, on the coalescence of nanocrystals. Chapter five contains detailed descriptions of the experiments that were involved during this work. A general conclusion is then followed by appendixes that contain extra-information related to this thesis.

This work describes an experimental investigation of methods of synthesis, determination of structural and physical properties, and analysis and correlation of the properties to the structures of semiconductor quantum dots and quantum dot-polymer hybrid structures. These structures are investigated for applications in flexible solar cell devices. The main synthesis process used in the work was a Laser-Assisted Spray (LAS) process that was developed in our laboratory to deposit surfactant-free PbSe quantum dot (QD) films directly on a substrate. The QD films formed by this technique are in close contact with each other forming a percolation path for charge transport. Analytical instruments that include Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) were used for structural characterization while optical absorption spectroscopy and photoluminescence were used for determining the quantum confinement of charge carriers in PbSe QDs. In addition, charge transport across lithographically patterned paths was used to determine the transport characteristics and generation of photocurrent in the fabricated structures. Absorption spectroscopy confirmed the quantum confinement of PbSe QDs deposited by LAS deposition. Room temperature current-voltage measurements across a 2 micrometer tunnel junction formed by the QDs produced a power-law dependence of the form I ∝ V2.19 that describes a percolation path of dimensionality slightly above two-dimensional. Absence of surfactants in LAS deposited films improved the conductivity by more than three orders of magnitude. Temperature dependent conductance studies showed thermally activated transport at high temperatures and temperature independent tunneling followed by previously unobserved metallic conduction at low temperatures. The LAS system was successfully modified by incorporating two spray nozzles to transport aerosols of two different precursors, one containing the QDs and the other containing the polymer. This new co-deposition system was successfully used to deposit QDs/Polymer hybrid structures. The TEM and XRD studies of LAS co-deposited films were shown to be uniformly distributed and crystalline. The photo-current experiments of QD/polymer hybrid composites showed clear evidence of enhanced carrier generation and transport as a result of intimate contact between quantum dots (QDs).

Ces dernières années, les nanocristaux (NCs) semi-conducteurs ont reçu un intérêt grandissant pour deux raisons principalement. D'une part, ces objets possèdent des tailles qui se situent entre celles des molécules et des matériaux cristallins. Leur étude d'un point de vue fondamental est par conséquent utile pour mieux comprendre les propriétés de la matière condensée en fonction de la dimension des objets étudiés . En particulier, les NCs de chalcogénures de plomb possèdent une constante diélectrique élevée (ε∞=23 pour PbSe) et des porteurs de charges ayant des faibles masses effectives, conduisant à la formation d'excitons avec un large rayon de Bohr effectif. De ce fait, ce sont des objets de choix pour étudier le régime de fort confinement quantique. D'autre part, la miniaturisation des composants électroniques nécessite l'utilisation d'objets semi-conducteurs aux dimensions de plus en plus petites, avec des coûts de fabrication les plus bas possibles. Les NCS semi-conducteurs, dont les synthèses chimiques sont généralement simples, répondent à cet enjeu et un certain nombre d'applications tirent avantage de leurs propriétés optiques. Dans la première partie de cette thèse, la méthode de synthèse des NCs de PbSe est décrite. Grâce à l'utilisation de plusieurs techniques de caractérisation (microscopies électroniques, diffraction des rayons X (XRD), diffraction électronique (SAED)), l'optimisation de cette méthode a conduit à l'obtention de NCs monodisperses en taille et possédant une structure cristalline parfaite. Dans un second temps, des études plus fines en spectroscopie Raman ont confirmé la qualité structurale des NCs. Elles ont aussi permis d'étudier les effets de confinement sur le spectre des phonons optiques longitudinaux. Enfin, les NCs de PbSe se détériorant rapidement à l'air, des structures coeur coquille ont été élaborées pour réaliser de l'ingénierie de bande dans des NCs à hétérostructures. En utilisant le rayonnement synchrotron et après avoir développé des techniques de dépôt de films ultra minces de NCs coeur-coquille PbSe/CdSe, la discontinuité de la bande de valence de ces structures a été étudiée par spectroscopie de photoélectrons.

Depuis les années 80, les nanocristaux (NCs) semi-conducteurs sont devenus très attractifs à cause d’énormes potentiels qu’ils représentent en termes d’applications technologiques. En effet, lorsque les dimensions d’un matériau deviennent inférieures ou comparables à la dimension caractéristique (rayon de Bohr) des porteurs de charges, les effets de confinement quantique conduisent à l’apparition de nouvelles propriétés physico-chimiques qui dépendent de la taille, la forme... Les NCs de chalcogénures de plomb possèdent des constantes diélectriques élevées et sont des matériaux de choix pour étudier les effets de confinement sur les propriétés des NCs dans le régime de confinement fort. Dans la première partie de cette thèse, les résultats obtenus sur la synthèse des NCs de PbSe et de PbSe/CdSe sont présentés. De taille très mono disperse et possédant une structure cristalline parfaite, ces NCs ont été synthétisés par voie colloïdale. Par la suite, les propriétés physico-chimiques de ces NCs ont été étudiées par diverses techniques de caractérisation (microscopies électroniques, diffraction des rayons X (XRD), diffraction électronique (SAED), spectroscopies Raman, absorption proche infrarouge et photoémission (UPS/XPS). Enfin, à l’aide des techniques de dépôts comme le Langmuir-Blodgett, des films minces de NCs de PbSe et de PbSe/CdSe ont été fabriqués. En utilisant un rayonnement synchrotron, la discontinuité des bandes dans les hétéro-nanostructures de PbSe/CdSe a été déterminée par XPS. Les résultats montrent un changement irréversible de la nature des NCs de PbSe/CdSe lors d’une irradiation prolongée de l’échantillon par un faisceau synchrotron<br>The tunability of electronic and optical properties of semiconductor nanocrystal (NC) is an important matter in nanotechnology because of their multiple potential applications in optoelectronics such as solar cells, nanotransistors, light emitters, biological markers…Core/shell QDs which are heterogeneous NCs have attracted increasing attention over the past decade, especially because of their enhanced photoluminescence properties and the possibility to create spatially separated excitons by means of a staggered core/shell band alignment. We studied lead chalcogenide NCs because of their unique physical properties which are very different from those of their corresponding bulk materials. Their high dielectric constant (ε∞=23 for PbSe) and the small effective masses of their electron and hole, create excitons with a relatively large effective Bohr radii. These properties lead to a strong confinement of the charge carriers and phonons., thus making them them promising building blocks for a wide number of applications. In the first part of this work, PbSe and PbSe/CdSe NCs with a narrow size distribution and high structural quality have been synthesized, using a colloidal route. Characterizations have been performed using several techniques (electron microscopy, X-ray diffraction (XRD), electron diffraction (SAED), photoemission (XPS/UPS), Raman and absorption spectroscopic measurements).By using deposition techniques such as Langmuir-Blodgett deposition, homogenous, compact thin films of PbSe and PbSe/CdSe NCs have been fabricated. UPS/XPS measurements performed with synchrotron radiations give the valence band offset between the core and the shell of these core/shell NCs

L'heteroepitaxie pbse sur si est realisee par epitaxie par jets moleculaires en utilisant des couches d'adaptation en caf#2 et baf#2 qui ont pour but de resorber le desaccord de parametre de maille (environ douze pourcent) et la difference des coefficients d'expansion thermique (un facteur huit entre le pbse et le si). Dans ce travail, nous nous interessons a l'identification et a l'interpretation des mecanismes de la croissance de ces composes. On s'attache en particulier a determiner les conditions permettant d'elaborer un materiau pbse, dont les proprietes structurales et electriques, sont optimales pour la realisation de detecteurs infra-rouge. L'utilisation de la microscopie electronique en transmission nous permet d'etudier les proprietes structurales ainsi que leur variation avec les parametres de croissance (en particulier la structure des couches d'adaptation en fluorures). Par exemple, dans le cas du systeme caf#2/si, nous etudions l'evolution de la contrainte residuelle avec l'epaisseur. Les observations experimentales permettent d'identifier un mode de croissance pseudomorphique et une epaisseur critique comprise entre vingt et soixante angstroems. La reduction des defauts presents dans la couche pbse est clairement dependante de la qualite cristalline et de l'epaisseur des couches d'adaptation. Ces resultats sont correles et completes par des observations de microscopie a force atomique et des analyses metallographiques

Nanoparticles represent promising carriers for controlled drug delivery. In this project threedifferent intruments: Zetasizer, Nanosight and Gas Chromatography, have been used to detect and analyse degradation of monodisperse poly butylcyanoacrylate (PBCA) and polyoctylcyanoacrylate (POCA) nanoparticles with a mean size diameter of 145 and 155 nm,respectively. It was found that the Nanosight and Gas Chromatography are valuable instrumentsfor detecting and analysing degradation, whereas the Zetasizer turned out to giveunreliable results because of increasing polydispersity in the samples. PBCA and POCAparticles were tested in two different setups. One including a dialysis setup in room temperature,in which the solvent was regularly exchanged. The other consisted of reagent bottlesheld in an oven at 37C. In the dialysis method the influence of buffers with pH 4.0, pH5.5 and pH 7.4 were tested. In the reagent bottles different mediums were tested, like cellmedium, blood serum and buffer pH 7.4 with and without the enzyme esterase. From theseexperiments it became clear that PBCA particles degraded significantly faster than POCAparticles in all tested mediums. Degradation of PBCA particles were also strongly affectedby the pH. At pH 4.0 there was little (10%) or no degradation still after 30 days. The concentration of PBCA particles in pH 7.4 decayed as a 1/x -function, in which 53\% of the PBCA particles in buffer pH 7.4 have been degraded after 8.5 hours.The degradation-rate for PBCA and POCA in blood serum was approximately similar as in buffer pH 7.4, whereas in cell medium it was slightly slower.

Sodium manganese hexacyanoferrate (NaMnHCF) and its derivatives have been synthesized by simple co-precipitation method with addition of the citric and ascorbic acids respectively. The correspondent crystal structure, water content, chemical formula and a deep structural investigation of prepared samples have been performed by means of the combination of the laboratory and synchrotron techniques (PXRD, FT-IR, TGA, MP-AES and XAS). Electrochemical tests have been done using three-electrode system in sodium nitrate solution at different concentration. From cyclic voltammetry curves, Fe3+/2+ redox peak has been observed, whereas Mn3+/2+ peak was not always evident. Structural stability of the cycled samples has then been tested using 2D XRF imaging and Transmission X-ray microscopy (TXM) techniques. The intercalation of NaMnHCF after 20 cycles has been found by micro-XANES analysis of the highlighted spots which have been found in the XRF images. TXM has also confirmed the appearance of the intercalated particles after 50 cycles comparing the spectra between charged and discharged materials at three different edges (Mn, Fe and N). However, by comparison with lithium samples, it seems obvious that sodium samples are more homogeneous and intercalation is at the very beginning indicating the relative structural stability of sodium manganese hexacyanoferrate electrode material.

<p> Current global energy usage is largely dependent on non-renewable resources such as fossil fuels. Research is expanding into alternative, renewable energy sources such as solar energy. Of specific focus is research into the use of metal chalcoginide semiconductor nanoparticles as a cost-efficient platform for future use in solar applications. These semiconductor nanoparticles have size-dependent electronic band gaps within the solar spectrum and can be deposited into thin films from colloidal solutions. To date, most electronic studies have focused on thin films with disordered morphologies, where the dominant inter-nanoparticle charge transport mechanism is hopping. Highly spatially ordered metal chalcoginide nanoparticle films may have the ability to form extended Bloch states, thereby resulting in more efficient charge transport. This work focuses on fabricating both highly spatially ordered and highly disordered PbSe nanoparticle thin films to compare their electronic properties and elucidate charge transport mechanisms.</p>

xvi, 145 p. : ill. (some col.)<br>The structures of several compounds in the [(PbSe)0.99]m[WSe2]n, [(PbSe)1.00]1[MoSe2]1, and [(SnSe)1.03]1[MoSe2]1 systems were determined using x-ray data. The structural determination using Rietveld methods was complicated by the strong preferred orientation of the samples, which resulted in x-ray diffraction scans with either 00l or hk0 reflections depending on the orientation of the sample in the diffractometer. Rietveld refinements of the [(PbSe)0.99]1[WSe2]1, [(PbSe)1.00]1[MoSe2]1, and [(SnSe)1.03]1[MoSe2]1 samples were compared to single crystal sample refinement results for [(MX)1+d]1[TX2]1, where M is a metal, T is a transition, X is a chalcogen, and d is the misfit parameter. The structural refinement yielded rock salt layer puckering values of 25 pm, 23 pm, and 36 pm for [(PbSe)0.99]1[WSe2]1, [(PbSe)1.00]1[MoSe2]1, and [(SnSe)1.03]1[MoSe2]1, respectively, which are all within the established literature range of 20 pm to 60 pm. The refinement of the hk0 reflections confirmed that the in plane structures were consistent with the dichalcogenide (P63mmc) and rock salt (Fm3m) structure types. Structures for the [(PbSe)0.99]m[WSe2]m isomer series where m = 1 to 5 were determined, and a systematic trend in structure as a function of the thickness of the constituent layers was discovered. The structure of the rock salt constituent was found to distort into pairs, forming alternating long and short distances along the c axis. This distortion decreases as the number of rock salt planes increases from 4 to 6 to 8 and is either absent or nearly so in compounds with a larger number of rock salt planes. The puckering distortion at the interface between the rock salt and the dichalcogenide is also observed in the inner rock salt layers but decreases in magnitude moving away from the rock salt – dichalcogenide interface. Structures of [(PbSe)0.99]m[WSe2]n where m = 1 or 2 and n = 1 or 2 were also determined. The degree of structural distortion is a function of the ratio of rock salt to dichalcogenide layers. This dissertation includes unpublished co-authored material.<br>Committee in charge: Dr. Thomas R. Dyke, Ph.D., Chairperson; Dr. David C. Johnson, Ph.D., Advisor; Dr. Catherine J. Page, Ph.D., Member; Dr. Andrew H. Marcus, Ph.D., Member; Dr. John L. Hardwick, Ph.D., Member; Dr. Richard Taylor, Ph.D., Outside Member

Joint Applied Project<br>GAO report 05-274 states nearly half of an organization's yearly budget is being spent on services. Consequently, DoD must ensure that contractors performing these services are being effectively monitored. The purpose of this joint applied project is to examine IT performance based service acquisitions and assess what performance measurements are being used to gauge the contractor's effectiveness. This research project will provide a literary review of Performance Based Contracts (PBCs), Performance Based Service Contracts (PBSC), Performance Based Service Acquisition (PBSA) and related topics. This review will be conducted using various Governmental legislative and regulatory guidance and best commercial practices. The research will include a gathering of survey information from contracting officers, Directors of Information Management offices, Information Technology (IT) technical personnel and TACOM IT contractors. This information will then provide a comparative analysis for recommendations and conclusions. To conclude, this joint applied project will include creating and posting performance measurement guidance for the TACOM Community website to provide all contracting personnel with the means to develop performance measures for IT performance based service contracts.

Nesta dissertação são apresentados os resultados da síntese de nanocristais (NCs) de PbSe em substratos de Si e SOI. O material foi produzido pela técnica de Síntese por Feixe de Íons (IBS) seguido de tratamentos térmicos em alta temperatura. As amostras foram caracterizadas pelas técnicas de Retroespalhamento Rutherford (RBS) e Microscopia Eletrônica de Transmissão (TEM). O estudo abrangeu amostras implantadas apenas com Pb ou com Se, ou amostras sequencialmente implantadas com Pb e Se. As implantações foram realizadas com substrato aquecido a Ti = 400 °C para evitar amorfização, variandose parâmetros de implantação como fluência, energia e ordem de implantação (primeiro Se ou Pb). Os recozimentos foram realizados a diferentes temperaturas e tempos. Os resultados foram discutidos em termos da retenção dos íons e da reação de formação do PbSe. Os principais resultados podem ser resumidos da seguinte forma. Durante as implantações ocorrem perdas tanto de Pb como de Se, atribuídas a processos de difusão auxiliada por irradiação. Nas amostras implantadas com apenas um elemento não ocorrem perdas durante os tratamentos térmicos. Contudo, nas amostras implantadas com Pb e Se, ocorrem perdas tanto de Pb como de Se. Este fenômeno é discutido considerando difusão pela matriz e evaporação pela superfície. O aumento das perdas foi associado à reação de formação do composto PbSe. Esta reação produz nanocristais, formando discordâncias devido ao desajuste de rede cristalina nas interfaces PbSe/Si. As perdas de Pb ocorrem preferencialmente através de difusão em discordâncias. Diferentemente do Pb, os átomos de Se reagem de diferentes formas com a matriz, permanecendo retidos no substrato. As Distribuições em Tamanho de NCs (DTNs) possuem forma característica e pouca variação de forma em função do tempo, não sendo observado crescimento competitivo. Estes resultados podem ser interpretados com base em argumentos termodinâmicos. A estabilidade do sistema NCs de PbSe em matriz de Si ocorre devido a minimização da energia de superfície, através da formação de interfaces coerentes, semi-coerentes e de estruturas caroço-casca (caroço de PbSe e casca de Se) com interfaces Se/Si. Para tanto a reação de síntese do PbSe produz NCs com uma coleção de orientações específicas em relação a estrutura cristalina do Si. Análises das micrografias de alta resolução com técnicas de Transformada de Fourier demonstram que muitos destes NCs são deformados plasticamente para diminuir o desajuste com o Si. O presente estudo mostra que é possível produzir NCs de PbSe termicamente estáveis e cristalograficamente orientados em relação a estrutura cristalina do Si. A baixa entalpia de formação do PbSe e baixa solubilidade dos átomos de Pb e de Se favorece a síntese dos NCs. Contudo, o comportamento químico e cinético do sistema é complexo devido as diferentes interações Pb-Si e Se-Si.<br>This work focuses on the synthesis of PbSe nanocrystals (NCs) in Si and SOI substrates. The NCs are produced by Ion Beam Synthesis (IBS) technique followed by thermal treatments at high temperatures. The samples are characterized by Rutherford Backscattering Spectrometry (RBS) and Transmission Electron Microscopy (TEM) techniques. The study comprises samples implanted with only one ion (Pb or Se) and samples implanted sequentially with Pb and Se, considering distinct implantation parameters (fluence, energy and ion sequence), performed at high temperature Ti = 400 °C to avoid amorphization. The thermal treatmen ts are done at distinct temperatures and times and the results are discussed in terms of the ion retention and of the PbSe compound formation. The most important results can be summarized as follow. During the implantations, Pb and Se losses take place and this phenomenon is attributed to the radiation enhanced diffusion process. Elemental losses cannot be detected for samples implanted with only one element. As opposed to this behavior, significant losses are observed for the co-implanted samples. These losses are attributed to the PbSe synthesis reaction. The formation of the NCs occurs concomitantly with the formation of treading dislocations induced by the large mismatch of the crystal PbSe/Si structures. The losses of Pb atoms can be attributed to a pipe diffusion processes along the dislocations. In contrast, the Se atoms tend to form atomic clusters and chemical bonds with Si crystal defects, and therefore are retained inside the matrix. The evolution of the NC size-distribution function is investigated, but no significant coarsening is observed. The results obtained are discussed using thermodynamic arguments. The thermal stability of the PbSe NCs is related to the formation of coherent, semicoherent interfaces as well as core-shell structures. The orientations of the PbSe NCs with respect to the Si matrix occur within a limited set of possibilities. High resolution TEM micrographs are analyzed using a Fast Fourier Transform method, which reveals the existence of plastically and elastically deformed interfaces. This study demonstrates that thermally stable and epitaxially oriented PbSe NCs can be synthesized in crystalline Silicon matrix. Their synthesis is facilitated by the low formation enthalpy and by the low solubility limit of the Pb and Se atoms within the Si matrix. However, the kinetic and chemical behavior of the process is rather complex due to the distinct Pb-Si and Se-Si interactions.

Ce travail de recherche consiste à étudier les relations structure-propriétés de mélanges biopolymères à base de poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) et poly(butylène succinate) (PBS). Il est divisé en trois parties. La première partie est consacrée à l'étude des propriétés des mélanges PHBV/PBS préparés par voie fondue en fonction de la composition en termes de morphologie et de propriétés rhéologiques, mécaniques, thermiques et barrières. Les résultats obtenus ont été discutés par rapport aux polymères de base. La deuxième partie est consacrée à la compatibilisation des mélanges PHBV/PBS et l'amélioration des interactions à l'interface. Les effets de l'incorporation de la sépiolite à 5% en masse et du PHBV greffé par de l’anhydride maléique (PHBV-g-MA) à 5% en masse ont été étudiés en termes de changements morphologiques montrant un effet synergique entre le compatibilisant et la nanocharge sur les l’ensemble des propriétés des mélanges PHBV/PBS. Enfin, une étude sur le recyclage a été menée à travers une évaluation des effets du nombre de cycles d'extrusion sur les propriétés des matériaux. Elle révèle qu'après 6 cycles d'extrusion, la dégradation thermo-mécanique du PHBV est significativement réduite en présence du PBS<br>The main objective of this work was to study the structure-properties relationships of biopolymerblends based on poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polybutylene succinate (PBS). The work was devised into three parts. The first part was devoted to the study of the properties of PHBV/PBS blends prepared by melt compounding at different weight ratio in terms of morphology and properties. The results obtained were discussed in terms of properties and compared with the neat polymers. The second part was devoted to the study of compatibility of PHBV/PBS blends aiming to improve the interactions at the interface between the two components. The effects of both sepiolite (5% wt.) and PHBV-g-MA (5% wt.) were studied in terms of properties. The results showed a synergistic effect between the compatibilizer PHBV-g-MA and the nanofiller sepiolite though an increase in thermal, mechanical and rheological properties. The last part dealing with the recyclability of PHBV/PBS through the study of the effects of repeated extrusion cycles on the properties of materials. The results showed that after 6 reprocessing cycles the thermo-mechanical degradation of PHBV is significantly reduced in the presence of PBS

Comprehensive evaluation of performance analysis of PBS INDUSTRY, a.s. When evaluating the performance of PBS INDUSTRY, a.s. the financial statements of the company for the period of 2005 -- 2008 are used. Performance evaluation is done through traditional methods of financial analysis and modern methods of economic added value. The interpretation of analytical results and recommendations was made.

Nanocrystal films may be used as detector material in sensors, as charge storage or conducting channels in devices. In this work lead sulphide (PbS) nanocrystals are generated in the gas-phase and deposited onto substrates forming nanocrystal films. A technology is developed for lateral structuring of these films on the substrate and to process them further by microelectronic standard processes. The pattern of the nanocrystal film is scaled down by several hundreds of nanometers compared to the used photoresist mask pattern. The responsible mechanism is found by consideration of physical mechanisms and usage of a trajectory simulation program. For basic electrical investigation a system is designed for production of nanocrystal films and electrical characterization under clean conditions. Noise measurements and I-V characterizations are performed. Both, single charge transport and charge transport through the interface of nanocrystal film and substrate have been found. The volume of the nanocrystal film is for the current transport not important. PbS nanocrystal films can be used in future devices for definition of high resolution current paths. Current designs can be used to downscale the device patterns without applying high resolution lithography. The parallel process technology with optical lithography still can be used to implement the films into microelectronic devices. With the trajectory simulation program the geometry can be predicted. The developed technology and the results can be transmitted to other material systems.

This thesis describes the optical and electrical properties of colloidal PbS nanocrystals synthesized in aqueous solution and comprising different capping ligands and/or matrices. Post-synthesis thermal annealing of thiol-capped PbS colloidal quantum dots (QDs) is discussed and shown to provide a novel means of tailoring the morphological and electronic properties of the QDs. Two different regimes are reported: at low annealing temperatures (< 80oC), the annealing provides a simple strategy for controlling and narrowing the QD size distribution and photoluminescence emission. At higher annealing temperatures, the displacement of the thiol-ligands promotes the fusion of nearby quantum dots thus leading to interconnected nanocrystals. A study of the circularly polarized magneto- photoluminescence of colloidal PbS nanocrystals under the influence of a magnetic field up to 30T is presented. A semiclassical model for the population of polarized excitons is used to account for the measured magnetic field and temperature dependence of the degree of circular polarization of the QD photoluminescence. The g-factor, gX, of the exciton and its dependence on the QD size is reported for the first time. The value of gX increases from 0.1 to 0.3 at low temperature with decreasing the nanocrystal diameter from 9 to 4 nm. The transport properties of a PbS QDs thin film deposited between two electrodes are investigated. This study reveals a non-linear dependence of the current on the applied bias. At low temperature (T<100 K), the conduction is limited by the charging energy (~20 meV) of the quantum dot. The fabrication of a solid-state device based on porous TiO2 impregnated with PbS QDs is discussed. The photovoltaic response of the device in the visible and near infrared wavelength range is obtained by exploiting the Schottky junction that forms at the interface between the PbS/TiO2 film and a metallic contact.

The diploma thesis is focused on cost control management in a manufacturing company. The diploma thesis deals with the calculation of product. It describes existing system of calculations and on the basis of theoretical knowledge suggest effective solutions. This solution should help to find hidden costs.

The purpose of this analysis is used PBS Turbo turbochargers like a steam-air turbine in the Flexible Energy System. The System is analogy of Brayton cycle with high efficiency, but heat is transferred to the cycle through a heat exchanger. Main parts of this work are the literature search, the thermodynamic model of the steam-air cycle, and solution for other possibilities. The goal is to find maximum available electrical output and efficiency. The thermodynamic model is used to: - check computation of the standard turbocharger - computation of the steam-air turbine contain one turbocharger - computation of the steam-air turbine contain two turbochargers. The steam-air turbine is different from the turbocharger. They are compared and than there is found some new design of the new steam-air turbine. The one-turbocharger steam-air turbine is used to test steam-air cycle. The double-turbocharger steam-air turbine is suitable for Flexible Energy System. This solution has a lot of advantages.