Esta tese tem como objetivo contribuir para o conhecimento e desenvolvimento das células solares sensibilizadas por corantes, através da elaboração de novas espécies supramoleculares e de estudos fundamentais de caracterização do filme de TiO2-P25 e da interface TiO2-Corante pela técnica de microscopia Raman confocal. Os estudos de microcopia Raman confocal da distribuição das fases cristalinas rutilo e anatase em filmes de TiO2-P25 (Degussa) mostraram que a fase rutilo está presente em agregados de diferentes tamanhos (de 250 nm a 3 µm) distribuídos na fase anatase e que estes agregados permaneceram mesmo após os processos de preparação da suspensão coloidal. Na presença do corante N3, verificou-se que a irradiação com laser em 532 nm, usando potência acima de 25 mW cm-2, provoca a absorção e posterior combustão do filme interfacial, com drásticas mudanças na morfologia visualizadas por microscopia Raman confocal, revelando a ocorrência da transformação de anatase em rutilo na região de incidência do feixe de laser. Outro ponto investigado nesta tese, foi a síntese e aplicação de novos sensibilizadores supramoleculares em células solares sensibilizadas por corante (DSC), visando diminuir os processos de recombinação e melhor aproveitamento do espectro solar através da estabilização do corante foto-oxidado e da transferência vetorial de elétron/energia. Além dos trabalhos com novas porfirinas supramoleculares, reproduzidas no apêndice, esta tese apresenta um estudo detalhado de uma série, formada por três espécies diméricas, constituídas pelas unidades [Ru(dcbH2)Cl]+ e [Ru(dmb)2Cl]+, unidas por ligantes ponte com dimensões lineares crescentes, isto é: bpy, bpe e bpeb (dcbH2= ácido-2,2\'-bipiridina-4,4\'-dicarboxílico, dmb= 4,4\'-dimetil-2,2\'- bipiridina, bpy= 4,4\'-bipiridina, bpe= trans-1,2-bis(4-piridil)-etileno e bpeb= trans-1,4- bis[2-(piridil)etenil]-benzeno). O rendimento global das DSCs correspondentes cresceram com o aumento do tamanho da ponte, passando de 2,78 % para o corante dim-Ru-bpy, para 2,89 e 3,25 % nos corantes dim-Ru-bpe e dim-Rbpeb, respectivamente. Foi observado que os valores de Jsc e η têm correlação linear com a distância de separação do buraco e da superfície do eletrodo de TiO2, ratificando que o processo de retardação da recombinação de carga, causado pelo aumento da ponte, é um fator muito importante para esta classe de compostos. Os resultados de IPCE mostraram que a unidade [Ru(dmb)2Cl(P)]+ também é responsável pela fotoinjeção de elétrons no TiO2. Assim, a excitação de qualquer uma das unidades, sempre acaba formando a espécie TiO2(e-)-Ru-Ru(h+) no filme interfacial. Os resultados confirmam as expectativas esperadas no planejamento energético vetorial, no qual o HOMO foi centrado na unidade distante da superfície e o LUMO ficou sobre a dcbH2 diretamente ancorada no superfície do TiO2. / This thesis encompasses our efforts to improve the knowledge and contribute to the development of dye-sensitized solar cells, by focusing on supramolecular design of new dyes and on critical aspects of the morphology of the TiO2-P25 and TiO2-Dye interfaces, as probed by confocal Raman microscopy. According to Raman imaging of the crystalline phase distribution of TiO2-P25 (Degussa) rutile was present as aggregates of different sizes (from 250 nm to 3 µm) dispersed in the 25 nm anatase powder, persisting even after applying criterious procedures for generating uniform colloidal suspensions. In addition, the irradiation of TiO2-P25 films containing adsorbed N3 dye, using a 532 nm laser (power over to 25 mW cm-2) led to the absorption and instantaneous combustion of the dye, promoting drastic local changes associated with the anatase to rutile conversion. The design and application of new supramolecular sensitizers in DSC has also been pursued, aiming an improvement of efficiency by slowing down the electron-hole recombination process, while enhancing the light harvesting effects in the visible range by means of vectorial electron/energy transfer. Studies concerning another efficient supramolecular porphyrin dye, have also been performed and published (Appendix). As the main subject, a series of dimeric species have been reported. They were based on the [Ru(dcbH2)Cl]+ and [Ru(dmb)2Cl]+ units connected by linear bridging ligands of increasing lengths, such as: bpy, bpe and bpeb (dcbH2= 2,2\'-bipyridine-4,4\'-dicarboxylic acid, dmb= 4,4\'-dimethyl-2,2\'-bipyridine, bpy= 4,4\'-bipyridine, bpe= trans-1,2-bis(4- pyridyl)-ethylene e bpeb= trans-1,4-bis[2-(4-pyridyl)ethenyl]-benzene). The overall yield of the corresponding DSCs increased with the bridging ligand length, from 2.78 % for dim-Ru-bpy, to 2.89 % and 3.25 % for dim-Ru-bpe and dim-Ru-bpeb, respectively. The electrochemical parameters associated with the short circuit current exhibited a linear correlation with the hole separation distance between the TiO2 electrode and the binuclear dye terminal, confirming that the retardation of charge recombination through the increasing distance is indeed a relevant factor for this series of compounds. The IPCE results indicated that the [Ru(dmb)2Cl(P)]+ unit is also involved in electron transfer, such that the dye excitation always leads the TiO2(e-)-Ru-Ru(h+) species. This conclusion confirmed the success of the supramolecular design and vectorial transfer strategy, in which the HOMO center was placed far away from the surface, but in communication with the LUMO center located at the dcbH2 group anchored on TiO2.

L'objet de cette thèse est l'étude de la pénétration des actifs cosmétiques dans la peau. Les axes d'investigation principaux ont concerné l'influence des propriétés physicochimiques des actifs et des ingrédients de la formule sur les mécanismes de pénétration. Les actifs cosmétiques choisis sont le rétinol, actif lipophile, et la caféine, actif hydrophile. Les formulations investiguées sont des émulsions de type huile dans eau, comparées aux solutions de tensioactifs correspondantes. Trois huiles cosmétiques ont été utilisées: Butylène glycol de cocoate, Octyldodecyl myristate et la Paraffine liquide, stabilisées en émulsion avec des tensioactifs ester de polyéthylène glycol (PEG20 et PEG6) possédant des longueurs de chaîne carbonées variables (C8, C12, C18 et C18:1). La pénétration percutanée a été mesurée quantitativement en utilisant la méthode des cellules de diffusion de Franz en fonctionnement statique et dynamique et qualitativement par la microscopie confocale Raman. Avec cette combinaison de techniques analytiques, il est possible, de mesurer la pénétration et d’évaluer l'impact de chaque composant de la formulation sur la pénétration cutanée d'un actif. Une corrélation a pu être établie entre l’effet fluidifiant d’une huile et l’augmentation de la pénétration du rétinol. Par ailleurs les tensioactifs, même s’ils ont montré un effet moindre en terme de fluidification conduisent également à une augmentation de la pénétration en raison d’une variation du coefficient de partage de l’actif entre la formule et la peau. Concernant la caféine, l’influence de la structure des tensioactifs et en particulier de la longueur de chaîne carbonée a été mise en évidence / The purpose of this thesis is to study the penetration of cosmetics actives into the skin. The main lines of investigation concerned the influence of actives and formulation components physicochemical properties on the penetration mechanisms. The selected cosmetic actives are retinol, lipophilic, and caffeine, hydrophilic. The investigated formulations are oil in water emulsions, compared to their corresponding surfactant solutions. Three cosmetic oils were used: Butylene glycol cocoate, Octyldodecyl myristate and liquid paraffin. Emulsions are stabilized with polyethylene glycol ester surfactants (PEG20 and PEG6) having variable carbon chain lengths (C8, C12, C18 and C18: 1). Percutaneous penetration was measured quantitatively using Franz diffusion cells in a static and dynamic way and qualitatively by confocal Raman microscopy. With this combination of analytical techniques, it is possible to measure the penetration and evaluate the impact of each formulation component on skin penetration of an active. A correlation could be established between the fluidizing effect of an oil and the increase in retinol penetration. Moreover, the surfactants, although they showed less effect in terms of fluidizing also lead to an increase in penetration due to a variation of the active partition coefficient between the formula and the skin. Regarding caffeine, the influence of the surfactant structure and in particular the carbon chain length has been pointed out

Les taches blanches sont liées à l'hypominéralisation sous la surface de l'émail et sont la 1ère étape du développement de la carie dentaire. La détection précoce des caries dentaires naissantes avant qu'elles n'atteignent le stade de la cavitation offre une opportunité pour des soins dentaires efficaces. Pour réaliser les objectifs de cette étude qui sont de renforcer l'idiome des soins minimalement invasifs, nous avons identifié un modèle de cycle de pH modifié qui permet d’imiter les conditions intra-buccales qui conduisent à la formation de lésions de type tache blanche, dans un court laps de temps. Des techniques optiques non invasives, comme la microscopie Raman confocale et la microscopie multiphotonique, ont été utilisées dans cette étude pour détecter de petits changements dans la composition chimique de l'émail in vitro.De plus, la technique de nano-indentation a été appliquée pour étudier les changements dans les propriétés mécaniques de l'émail et les relier à ceux affectant sa composition chimique après l'induction des caries, afin d‘ajouter de la spécificité chimique-mécanique aux informations sur les lésions sous-surface de l'émail. Les résultats obtenus démontrent un grand potentiel pour les techniques examinées, fournissant une base pour des applications intéressantes dans le diagnostic clinique de différentes pathologies dentaires. Pour résoudre le problème du traitement des lésions primitives sans intervention chirurgicale, l'efficacité de la crème GC Tooth Mousse et du dentifrice contenant de la nano-hydroxyapatite «KAREX» dans l'amélioration de la reminéralisation de l'émail déminéralisé par la localisation du phosphate de calcium amorphe à la surface de la dent a été inspectée. L'étude a indiqué le manque de preuves fiables soutenant l'efficacité des agents reminéralisants dans le traitement des taches blanches. Ce travail doit être poursuivi par d'autres études in-vitro et par des études cliniques. / White spot lesion is the subsurface hypomineralization of enamel indicating the 1st stage of dental caries development. Early detection of incipient dental caries before it reaches the stage of cavitation offers an opportunity for effective dental care. The objectives of this study were to strengthen the idiom of minimally invasive treatment. In order to achieve the specified goals; we have identified a modified pH cycling model that can mimic the intraoral conditions leading to white spot lesions formation in a short time. In addition, non-invasive optical techniques, such as confocal Raman microscopy and multiphoton microscopy were used in this study to detect small changes in the enamel chemical composition in vitro.Furthermore, nano-indentation technique was used to detect the changes in the mechanical properties of enamel and relate them to those affecting its chemical composition after caries induction in order to add chemico-mechanical specificity in providing important information about subsurface lesions in enamel. The obtained results demonstrate a great potential for the examined techniques, providing a basis for interesting applications in the clinical diagnosis of various pathological conditions in dentistry. To treatment the incipient carious lesions non-invasively, the effectiveness of GC Tooth Mousse cream and nHA containing-dentifrice "KAREX" in the remineralization of demineralized enamel through localizing amorphous calcium phosphate at tooth surface has been inspected. The study indicated a lack of reliable evidence supporting the efficacy of remineralizing agents in the treatment of white spot lesions. Within the limitations of this study, further laboratory studies together with clinical research are therefore required to increase the available knowledge on this prevalent subject.

Nous avons étudié l'influence de la fabrication de guides d'ondes optiques par échange protonique doux(SPE) sur les cristaux de niobate de lithium (LN) polarisé périodiquement et nous avons montré que,dans certains cas, ce processus conduit à la création de nanodomaines en surface. Ces nanodomaines enforme d'aiguille peuvent être responsables de la réduction de l'efficacité de conversion non linéaireobservée dans les guides qui sont affectés. Nous avons également étudié l'influence de différents typesd'échange protonique sur la formation, par application d'un champ électrique, de domaines dans le LNcongruent. Cette étude montre que le seuil de nucléation peut être fortement réduit par la présence duguide d'onde et que l'apparition et le développement des domaines en forme de traits est fortementmodifiée. Elle montre également que la fusion des nanodomaines existants au voisinage des parois dedomaine aboutit à la formation de parois élargies et de domaines en forme de dendrites. En irradiantavec un faisceau d'électrons la surface Z- d'un échantillon de LN préalablement soumis à un échangeprotonique doux et recouvert d'une couche de résine électronique, nous avons réussi à former desdomaines avec des formes arbitraires. Par cette technique, nous avons fabriqué des domainespériodiques d'excellente qualité dans des cristaux présentant des guides canaux SPE. Des expériences degénération de deuxième harmonique dans ces guides nous ont permis d'obtenir des efficacités deconversion de 48%/W.cm2 ce qui est conforme aux prédictions ainsi que la forme des spectres d'accordde phase que nous avons observés. Ceci démontre tout l'intérêt de ce processus / The investigation of influence of the soft proton exchange (SPE) optical waveguide (WG) creation onperiodically poled lithium niobate (PPLN) has been done. It has been shown that the WG fabricationprocess can induce the formation of needle like nanodomains, which can be responsible for thedegradation of the nonlinear response of the WG created in PPLN crystals. The domain structure (DS)evolution has been studied in congruent lithium niobate (LN) crystals with surface layers modified bythree different proton exchange techniques. The significant decrease of the nucleation threshold fieldand qualitative change of domain rays nucleation and growth have been revealed. The formation of abroad domain boundary and dendrite domain structure as a result of nanodomains merging in front ofthe moving rays has been demonstrated. The formation of DS in LN with SPE by irradiation of coveredby electron resist polar surface of LN has been investigated. Formation of domains with arbitrary shapesas a result of discrete switching has been revealed. Finally, it has been demonstrated that electron beamirradiation of lithium niobate crystals with surface resist layer can produce high quality periodical domainpatterns after channel waveguide fabrication. Nonlinear characterizations show that the conversionefficiencies and the phase matching spectra conform to theoretical predictions, indicating that thiscombination presents a great interest for device fabrication. Second harmonic generation withnormalized nonlinear conversion efficiency up to 48%/(W cm2) has been achieved in such waveguides

In this work, the solubility of butyl paraben in 7 pure solvents and in 5 different ethanol-water mixtures has been determined from 1 ˚C to 50 ˚C. The solubility of ethyl paraben and propyl paraben in various solvents has been determined at 10 ˚C. The molar solubility of butyl paraben in pure solvents and its thermodynamic properties, measured by Differential Scanning Calorimetry, have been used to estimate the activity of the pure solid phase, and solution activity coefficients. More than 5000 nucleation experiments of ethyl paraben, propyl paraben and butyl paraben in ethyl acetate, acetone, methanol, ethanol, propanol and 70%, 90% ethanol aqueous solution have been performed. The induction time of each paraben has been determined at three different supersaturation levels in various solvents. The wide variation in induction time reveals the stochastic nature of nucleation. The solid-liquid interfacial energy, free energy of nucleation, nuclei critical radius and pre-exponential factor of parabens in these solvents have been determined according to the classical nucleation theory, and different methods of evaluation are compared. The interfacial energy of parabens in these solvents tends to increase with decreasing mole fraction solubility but the correlation is not very strong. The influence of solvent on nucleation of each paraben and nucleation behavior of parabens in each solvent is discussed. There is a trend in the data that the higher the boiling point of the solvent and the higher the melting point of the solute, the more difficult is the nucleation. This observation is paralleled by the fact that a metastable polymorph has a lower interfacial energy than the stable form, and that a solid compound with a higher melting point appears to have a higher solid-melt and solid-aqueous solution interfacial energy. It has been found that when a paraben is added to aqueous solutions with a certain proportion of ethanol, the solution separates into two immiscible liquid phases in equilibrium. The top layer is water-rich and the bottom layer is paraben-rich. The area in the ternary phase diagram of the liquid-liquid-phase separation region increases with increasing temperature. The area of the liquid-liquid-phase separation region decreases from butyl paraben, propyl paraben to ethyl paraben at the constant temperature. Cooling crystallization of solutions of different proportions of butyl paraben, water and ethanol have been carried out and recorded using the Focused Beam Reflectance Method, Particle Vision and Measurement, and in-situ Infrared Spectroscopy. The FBRM and IR curves and the PVM photos track the appearance of liquid-liquid phase separation and crystallization. The results suggest that the liquid-liquid phase separation has a negative influence on the crystal size distribution. The work illustrates how Process Analytical Technology (PAT) can be used to increase the understanding of complex crystallizations. By cooling crystallization of butyl paraben under conditions of liquid-liquid-phase separation, crystals consisting of a porous layer in between two solid layers have been produced. The outer layers are transparent and compact while the middle layer is full of pores. The thickness of the porous layer can reach more than half of the whole crystal. These sandwich crystals contain only one polymorph as determined by Confocal Raman Microscopy and single crystal X-Ray Diffraction. However, the middle layer material melts at lower temperature than outer layer material. / <p>QC 20130515</p> / investigate nucleation and crystallization of drug-like organic molecules