Foram investigadas através da técnica de absorção eletrônica Uv-Vis e emissão de fluorescência a interação entre uma série de porfirinas e zinco-porfirinas com o polímero de eumelanina sintética obtida pela auto-oxidação da L-DOPA (dihidroxi-fenilalanina). Ocorre a formação de dois complexos na interação entre as porfirinas catiônicas e a eumelanina. Um complexo mais fraco em concentrações mais baixas e intermediárias de eumelanina, e um complexo mais forte em concentrações maiores. Estes complexos podem ser observados pelas variações obtidas nos espectros de absorção em função da concentração da melanina. A eumelanina suprime eficientemente a fluorescência das porfirinas catiônicas, em um processo de supressão por esfera de ação. Este processo ocorre particularmente para os complexos fracos entre a porfirina e a eumelanina, podendo ser inferido pela natureza de polieletrólito da eumelanina que deve apresentar uma ampla superfície de contato carregada negativamente, facilitando a orientação das porfirinas em uma disposição planar em relação ao polímero. A determinação das constantes de supressão estáticas aparentes (KEA) mostra que os substituintes alquílicos influem consideravelmente na formação destes complexos com a eumelanina. As diferentes interações são devidas aos fatores estruturais tais como dimensão da porfirina, polarização dos substituintes e formação de interações de natureza hidrofóbica. As zinco-porfirinas são de forma geral menos suprimidas que as bases livres. Este comportamento pode ser uma evidencia da aproximação planar em relação ao polímero da melanina, uma vez que zinco porfirinas apresentam moléculas de água ligadas axialmente, logo estas moléculas coordenadas axialmente impediriam uma aproximação mais efetiva. Foi realizado um estudo da formação de filmes baseados na técnica de auto-montagem eletrostática entre as porfirinas e a melanina utilizando como substrato o vidro. Observa-se que a adsorção das porfirinas em vidro é diferenciada sendo a TBzPyP a base livre que apresenta a maior adsorção. Pelos espectros de emissão dos filmes de porfirina em vidro foi possível verificar que alguns derivados interagem com uma participação mais efetiva dos piridínios que outros em que a interação é menos direcionada. Nos filmes porfirina melanina também é observada a supressão de fluorescência da porfirina. A diferença na magnitude de supressão nos filmes sugere que estes derivados possam ser utilizados em sistemas de diagnóstico relacionados à detecção de tumores melanóticos. Em um estudo paralelo, foram investigadas as propriedades de fotoisomerização de grupos azobenzênicos coordenados axialmente a uma ftalocianina de Silício(IV). Este sistema apresenta fotoisomerização E-Z e isomerização térmica e sensibilizada para o processo Z-E. As conversões E-Z e Z-E seguem uma cinética de primeira ordem, sendo o processo térmico Z-E cerca de dez vezes mais lento que o fotoquímico E-Z. A intensidade de fluorescência da ftalocianina é dependente do estado de isomerização dos grupos axiais, sendo que a forma E apresenta maior emissão de fluorescência que a forma Z. Portanto este sistema se constitui em um dispositivo molecular do tipo “on-off”, onde a intensidade de fluorescência pode ser controlada por um estímulo externo, no caso o comprimento de onda de excitação para a reação E-Z direta ou Z-E sensibilizada. / In this work we have investigated the interaction between a series of cationic porphyrins and zinc-porphyrins and the synthetic eumelanin polymer obtained by the auto-oxidation of L-DOPA (dihidroxy-phenylalanine) by means of UV-Vis and fluorescence emission techniques. Weak and strong porphyrin-melanin complexes are formed, and the evolution from weak to strong complexes can be monitored by the UV-Vis changes in the pophyrin spectra as the melanin concentration increases. The porphyrin fluorescence emission is quenched efficiently by eumelanin in a “quenching sphere of action” mechanism. This quenching sphere of action process is mainly observed for the weak complexes, and can be rationalized considering the polyelectrolyte nature of the eumelanin polymer which provides a broad contact area coated negatively, that enables a planar approximation of the porphyrins. The apparent static quenching constants (KEA) show that the nature of the alkyl substiutents markedly influences the complex formation. Total porphyrin size, different polarization induced by substituents and specific hydrophobic interactions are probably responsible for the different porphyrin – melanin association, which in turn reflects in the quenching properties of each particular porphyrin - melanin complex. The corresponding Zinc-porphyrins are less efficiently quenched by eumelanin, probably due the fact this molecules are axially coordinated by a water molecule, precluding a more close approximation between zinc-porphyrin and the eumelanin polymer. Electrostatically self-assembled films of porphyrins and eumelanin on glass have been studied. Different porphyrin adsorption on glass were observed, and TBzPyP derivative shown the highest adsorption in the investigated porphyrin series. Fluorescence emission suggests different interaction properties of the adsorbed pophyrin on glass, with specific pyridinium participation for some porphyrin derivatives. Fluorescence quenching of the porphyrins is observed in porphyrin – melanin films. The differences observed in the quenching for each derivative suggest a possible application of these compounds for diagnostic procedures related to melanotic tumors. In a complementary study, have been investigated the photoisomerization properties of a Si(IV)-phthalocyanine axially coordinated by azobenzene groups. Photochemical E-Z and thermal and sensitized Z-E isomerization processes were observed. Both E-Z photochemical and Z-E thermal follow first-order kinetics. Z-E process as expected is considerably slower than E-Z. The pthalocyanine emission is dependent on the isomerization state of the apendent azobenze groups, and the E form is more emissive than the Z form. This system can be considered a molecular device since the emission properties of the phthalocyanine moiety can be modulated by the isomerization state of the axially coordinated azoarenes, creating an on-off (E-Z states) fluorescence signal, and differently from other reported systems the recovery of the initial state does not depend only on the rate of the thermal reaction, since it can be controlled by a sensitized mechanism. This system seems promising taking into account the stability of the axially coordinated moieties, the greater versatility in the achievement of the desired isomerization state and the broad spectral region considering both direct and sensitized excitation.

L’utilisation de revêtements et de couches minces déposés sur substrats est très recherchée dans de nombreuses applications. Les objectifs de ces revêtements et dépôts sont multiples (améliorer la durabilité des structures, leur résistance à l’usure et à la fatigue, etc.). D'autre part, les matériaux à gradient sont également développés en vue de répondre à de nouvelles exigences fonctionnelles, comme de meilleures tenues en température, en usure, en corrosion. Pour toutes ces applications, la caractérisation de ces revêtements et de ces matériaux à gradients, afin d’en déterminer leurs propriétés (épaisseur, constantes élastiques, adhérence, contraintes résiduelles, …etc), est déterminante pour le contrôle santé des pièces et pour leur fonctionnement optimal au cours de leur utilisation. Pour caractériser ces structures, nous avons choisi d’exploiter la dispersion des ondes de surface sur une large gamme de fréquences (10 à 60 MHz). Afin d’exciter ces ondes, des capteurs MEMS de type IDT-SAW ont été réalisés à différentes fréquences couvrant la totalité de la gamme fréquentielle considérée. L’excitation quasi-harmonique a été privilégiée dans le but d’obtenir des mesures précisesde vitesses de phase. Nous avons montré les potentialités de cette approche en caractérisant premièrement des structures à couche mince allant jusqu’à 500 nm et deuxièmement des structures amorphes à gradient de contraintes. / The use of coatings and thin layers deposited on substrates is highly sought in many applications. The objectives of these coatings and deposits are multiple (improve the durability of structures, their wear resistance and fatigue, etc.). On the other hand, gradient materials are being developed to meet new functional requirements, such as a better resistance to temperature, wear and corrosion. For all of these applications, the characterization of these coatings and gradient materials, in order to determine their properties (thickness, elastic constants, adherence, residual stresses, etc…), is decisive for the health control of pieces and for their optimum operation during their use. To characterize these structures, wechose to exploit the dispersion of surface acoustic waves over a wide frequency range (10 to 60 MHz).To excite these waves, SAW-IDT MEMS sensors have been carried out at different frequencies covering the entire frequency range we considered. The quasi-harmonic excitation was preferred to obtain accurate measures of phase velocities. We showed the potential of this approach by characterizing, first, thin layers structures (500 nm) and second, amorphous structures with a stressesgradient.

GLAST est la nouvelle génération de télescope spatial pour l'étude des rayons gamma et devrait très largement améliorer notre connaissance du ciel à haute énergie, dès son lancement en août 2007.<br />Les données du faisceau-test mené au GANIL avec des ions de basse énergie, ont permis de contribuer à l'étalonnage en énergie du LAT. Ces données ont été analysées pour mesurer la non-linéarité de la production de lumière dans le CsI en réponse au dépôt d'énergie des ions, des protons au krypton et pour des énergies allant de 0 à 73MeV par nucléon. Les résultats obtenus se sont révélés complémentaires aux mesures de scintillation du CsI, réalisées lors du faisceau-test mené au GSI pour des ions lourds relativistes . La connaissance de la non-linéarité de la réponse des cristaux de CsI de GLAST aux ions de haute énergie est indispensable pour réaliser l'étalonnage en énergie en orbite des détecteurs à l'aide des rayons cosmiques.<br /><br />Le rejet des évènements hadroniques est un autre problème clé pour GLAST, or, l'élaboration des algorithmes repose sur la simulation Monte-Carlo officielle de GLAST, GlastRelease. Les cascades hadroniques mesurées lors du faisceau-test mené au GSI et lors d'un autre faisceau-test mené au CERN sur le SPS, sont utilisées pour confronter les codes de simulation, disponibles sur la plate-forme logicielle GEANT4 qui est à la base de GlastRelease. En vérifiant la bonne reproduction de certaines observables simples, pour des cascades hadroniques générées par des protons ou de pions de .7GeV , 3.4GeV, 10GeV et 20GeV, on conclue qu'à haute énergie le modèle par défaut, LHEP, est valable, alors qu'à basse énergie, le modèle de cascade intranucléaire de Bertini devrait être utilisé.

Optical methods play an important role in process analytical technologies (PAT). Four examples of optical process and quality sensing (OPQS) are presented, which are based on three important experimental techniques: near-infrared absorption, luminescence quenching, and a novel method, photon density wave (PDW) spectroscopy. These are used to evaluate four process and quality parameters related to beer brewing and polyurethane (PU) foaming processes: the ethanol content and the oxygen (O2) content in beer, the biomass in a bioreactor, and the cellular structures of PU foam produced in a pilot production plant.

<p>In this thesis, regioregularpoly( 3-hexylthiophene) (rr-P3HT) polymer was used as a light absorption and electron donating material, while the C60 fullerene and its derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM) were used as electron acceptor materials. The effect of solvent to control the degree of mixing of the polymer and fullerene components, as well as the domain size and charge transport properties of the blends were investigated in detail using P3HT:C60 films. The photo-physical, structural and electrical transport properties of the polymer blends were carried out according to their ratios. A distinctive photoluminescence (PL) quenching effect was observed indicating a photo-induced electron transfer. In this thesis, the effect of solvents on the crystallization and interchain interaction of P3HT and C60 fullerene films were studied using XRD, UV-vis, PL, Raman and FTIR spectroscopy. The polymer blends formed with non-aromatic solvents exhibited an improved crystallinity and polymer morphology than that formed with aromatic solvents. An improved ordering was demonstrated in the polymer films spin coated from non-aromatic solvents. This indicates that the limited solubility of rr P3HT in a marginal solvent such as non-aromatic solvents can offer a strategy to obtain highly ordered crystal structures and lead directly to optimal morphologies on the films.</p>

The reduction behaviour of the olivine iron ore pellet MPBOwas studied in laboratory scale at KTH as well as in the LKABexperimental blast furnace. Initially, a newreduction-under-load, or so-called reduction/softening/melting,test equipment was developed. Experiments using differentreducing conditions, corresponding to different radialpositions of the blast furnace, were conducted. The experimentsincluded different temperature profiles, reducing atmospheresand mechanical loads applied on the sample bed to simulate thevarying conditions in the blast furnace process. The progressof reduction was investigated, as well as the processes ofsintering and contraction during reduction. A model of thecarburisation (pick-up of carbon by the reduced iron) andmelt-down process during rapid contraction was presented. Laboratory testing of MPBO pellets was compared with resultsfrom the LKAB experimental blast furnace. The reduction of ironore pellets in the experimental blast furnace was surveyed by adissection of the furnace after quenching. The high temperaturephenomena occurring when reducing the MPBO pellet, with limitedsoftening and a short temperature range of the melting process,resulting in a thin cohesive zone, were found to be the same inlaboratorytests and in the experimental blast furnace. Thereduction down through the burden of the experimental blastfurnace was similar, but not identical to the results of theRUL experiments. The differences were found to be due todifferent reducing conditions. Therefore, it was concluded thata simulation of the reduction occurring in the blast furnacecan be performed in laboratory scale, provided the experimentalconditions are correctly chosen. Finally, a modification to further improve the properties ofthe MPBO pellets was examined. With the aim to improve theblast furnace process, coating of blast furnace pellets wasinvestigated in laboratory scale, as well as in the LKABexperimental blast furnace. Olivine, dolomite and quartzitewere used as coating agents. In laboratory scale the stickingprevention action of the different coating materials wasverified, in established test methods as well as in new testmethods, modified for blast furnace conditions. Testing of thecoated pellets in the experimental blast furnace revealedseveral advantages; significantly reduced blast furnace fluedust generation, improved gas utilisation and a smoother blastfurnace operation with a potential for a lowered fuel rate. <b>Keywords:</b>Olivine, pellets, pellet testing,reduction/softening/melting, MPBO, blast furnace, reduction,quenching, dissection, coating, sticking, coated pellets.

The Small Cab-like Proteins (SCPs) in the cyanobacterium Synechocystis sp. PCC 6803 accumulate in cells grown under different stress conditions. Genes coding for SCPs have been found in all sequenced organisms performing oxygenic photosynthesis and even in the genomes of cyanophages. Deletion of multiple scp genes in Synechocystis resulted in mutants with severely impaired growth and altered pigment content. These findings indicate the importance of SCPs in photosynthesis; however, their specific function is not well understood. SCPs share a chlorophyll-binding motif with the plant light harvesting complex, suggesting that they bind chlorophyll. Here I describe my findings, which unambiguously show that SCPs are able to bind chlorophyll in vitro. Although they affect both the stoichiometric ratio of Photosystem I to II and chlorophyll stability, they do not seem to be directly involved in non-photochemical quenching. I was able to reveal the location of the SCPs within the cyanobacterial cell: in stressed cells they attach to Photosystem II in the thylakoid membrane. Furthermore, I revealed the presence of another light-harvesting like (Lil)/SCP protein in Synechocystis sp. PCC 6803. The gene, slr1544, codifying for this newly characterised LilA protein, co-transcribes together with scpD and also appears to bind to Photosystem II during stress.

Cette thèse a pour objet l'analyse de la cinétique de la conversion de l'acétaldéhyde, CH₃CHO, à des concentrations initiales inférieures ou égale à 5000 ppm dans un mélange de gaz à base d'azote et contenant jusqu'à 20% d'oxygène, à température ambiante. L'étude a été réalisée en utilisant trois réacteurs mettant en œuvre des décharges de qualités spatiales différentes. Il s'agit d'un réacteur (UV510) à décharge pré-ionisée (photo-déclenchée) par rayonnement UV produisant un plasma homogène, et de deux réacteurs à décharge à barrière diélectrique (DBD), de géométrie plane (plan-plan) et de géométrie cylindrique (tige-tube) alimentés par impulsion HT et produisant des plasmas non homogènes à faible (plan) ou forte (cylindre) filamentation ; un diagnostic d'imagerie rapide (ns) de la DBD de géométrie plane montre que le plasma peut être considéré quasi-homogène. En s'appuyant sur une modélisation 0D auto-cohérente de la décharge photo-déclenchée, l'étude de la cinétique du mélange N₂/CH₃CHO montre l'importance des états métastables de la molécule d'azote, triplet A³Σu⁺, et singlets (groupe a' ¹∑⁻u, a ¹∏g, et w ¹Δu) dans la dissociation de l'acétaldéhyde. Un coefficient minimum de 6.5×10⁻¹¹ cm³.s⁻¹ est estimé pour le quenching des singlets par l'acétaldéhyde. Le coefficient du triplet est estimé entre 4.2×10⁻¹¹ cm³.s⁻¹ et 6.5×10⁻¹¹ cm³.s⁻¹. Cette dissociation produit des radicaux (CH₃, CH₃CO, HCO, H, O) et des molécules (CH₄, CH₂CO, C₂H₄, C₂H₂, H₂, CO). Ainsi les sous-produits majoritaires mesurés à la fin de la post décharge temporelle sont le méthane, le dihydrogène, le monoxyde de carbone et l'éthane. Les minoritaires sont l'acétylène, l'éthène, l'acétone et l'acétonitrile. Dans les mélanges contenant de l'oxygène, l'importance de la dissociation de CH₃CHO par quenching des états métastables de N₂ diminue au profit des processus d'oxydation par le radical hydroxyle, OH, et l'oxygène atomique, O (³P). La mesure résolue en temps du radical OH dans la post-décharge du réacteur UV510 montre une très forte réactivité de ce radical avec les sous-produits de conversion de l'acétaldéhyde. Une densité maximum de OH égale à 3.5×10¹⁴ cm⁻³ a été mesurée pour 10 % d'oxygène et 5000 ppm d'acétaldéhyde. Le schéma cinétique adopté pour ces mélanges donne, par la modélisation auto-cohérente, une valeur de densité plus élevée. Toutefois, la conversion de l'acétaldéhyde dans N₂/O₂/CH₃CHO est bien expliquée par le modèle, de même que les concentrations produites de méthane et d'éthane. Enfin, la comparaison de l'efficacité énergétique des trois réacteurs étudiés montre que l'homogénéité de la décharge favorise, pour des milieux pauvres en oxygène (moins de 2 %), la conversion de l'acétaldéhyde.

Our group has developed a family of single molecules termed nanocars, which are aimed at performing controllable motion on surfaces. In this work, a series of light-activated motorized nanomachines incorporated with a MHz frequency light-activated unidirectional rotary motor were designed and synthesized. We hope the light-activated motor can serve as the powering unit for the nanomachines, and perform controllable translational motion on surfaces or in solution. A series of motorized nanovehicles intended for scanning tunneling microscopy (STM) imaging were designed and synthesized. A p-carborane-wheeled motorized nanocar was synthesized and monitored by STM. Single-molecule imaging was accomplished on a Cu(111) surface. However, further manipulations did lead to motor induced lateral motion. We attributed this result to the strong molecule-surface interactions between the p-carborane-wheeled nanocar and the Cu(111) surface. To fine-tune the molecule-surface interactions, an adamantane-wheeled motorized nanocar and a three-wheel nanoroadster were designed and synthesized. In addition, the STM substrates will be varied and different combinations of molecule-surface interactions will be studied. As a complimentary imaging method to STM, single-molecule fluorescence microscopy (SMFM) also provides single-molecule level resolution. Unlike STM experiment requires ultra-high vacuum and conductive substrate, SMFM experiment is conducted at ambient conditions and uses non-conductive substrate. This imaging method allows us to study another category of molecule-surface interactions. We plan to design a fluorescent motorized nanocar that is suitable for SMFM studies. However, both the motor and fluorophore are photochemically active molecules. In proximity, some undesired energy transfer or interference could occur. A cyanine 5- (cy5-) tagged motorized nanocar incorporated with the MHz motor was designed and synthesized in order to minimize the potential energy transfer or interference between the motor and the fluorophore. The SMFM study of this cy5-tagged motorized nanocar is currently undergoing. The design of light-activated motorized nanocar inspired the design of nanosubmarines. We used fluorescence quenching and fluorescence correlation spectroscopy (FCS) to study the diffusion of single molecules. The fluorescence quenching experiments of Ru(bpy)3+2 by a quenching nanosubmarine was conducted, but no motor induced acceleration of the molecule were observed. Another fluorescent nanosubmarine was monitored by FCS, and no increase of diffusion coefficient was found. Finally, a 1-D channel approach was adopted for decreasing the effects of Brownian motion, and acceleration of nanosubmarine was observed.

<p>The reduction behaviour of the olivine iron ore pellet MPBOwas studied in laboratory scale at KTH as well as in the LKABexperimental blast furnace. Initially, a newreduction-under-load, or so-called reduction/softening/melting,test equipment was developed. Experiments using differentreducing conditions, corresponding to different radialpositions of the blast furnace, were conducted. The experimentsincluded different temperature profiles, reducing atmospheresand mechanical loads applied on the sample bed to simulate thevarying conditions in the blast furnace process. The progressof reduction was investigated, as well as the processes ofsintering and contraction during reduction. A model of thecarburisation (pick-up of carbon by the reduced iron) andmelt-down process during rapid contraction was presented.</p><p>Laboratory testing of MPBO pellets was compared with resultsfrom the LKAB experimental blast furnace. The reduction of ironore pellets in the experimental blast furnace was surveyed by adissection of the furnace after quenching. The high temperaturephenomena occurring when reducing the MPBO pellet, with limitedsoftening and a short temperature range of the melting process,resulting in a thin cohesive zone, were found to be the same inlaboratorytests and in the experimental blast furnace. Thereduction down through the burden of the experimental blastfurnace was similar, but not identical to the results of theRUL experiments. The differences were found to be due todifferent reducing conditions. Therefore, it was concluded thata simulation of the reduction occurring in the blast furnacecan be performed in laboratory scale, provided the experimentalconditions are correctly chosen.</p><p>Finally, a modification to further improve the properties ofthe MPBO pellets was examined. With the aim to improve theblast furnace process, coating of blast furnace pellets wasinvestigated in laboratory scale, as well as in the LKABexperimental blast furnace. Olivine, dolomite and quartzitewere used as coating agents. In laboratory scale the stickingprevention action of the different coating materials wasverified, in established test methods as well as in new testmethods, modified for blast furnace conditions. Testing of thecoated pellets in the experimental blast furnace revealedseveral advantages; significantly reduced blast furnace fluedust generation, improved gas utilisation and a smoother blastfurnace operation with a potential for a lowered fuel rate.</p><p><b>Keywords:</b>Olivine, pellets, pellet testing,reduction/softening/melting, MPBO, blast furnace, reduction,quenching, dissection, coating, sticking, coated pellets.</p>