Tesis sobre el tema "Physico-chemical characterization by fluorescence"

Dans le domaine de l’analyse de défaillance et plus particulièrement la contamination moléculaire et particulaire, il est crucial de pouvoir détecter toute trace de contaminants durant l’intégration d’un engin orbital. Dans ce contexte, la fluorescence permet non seulement de détecter mais aussi de discriminer les contaminants. Pour ce projet, nous avons donc développé un instrument hyperspectral large-bande (UV-Vis-NIR) de 330 à 1000 nm pour pouvoir détecter un large panel de contaminants. Il s’agit d’un montage catoptrique permettant de s’affranchir des aberrations chromatiques. Il présente un champ de vue de 3,5° pour une résolution angulaire de 25 secondes d’arc. Il a été conçu pour être portable et son ensemble mécanique figé permet un alignement optique simple à mettre en œuvre et une réalisation rapide des fichiers de calibration entre deux scènes. Nous avons mesuré une résolution spectrale de 1 nm dans l’UV, 2 à 3 nm dans le visible et 5 nm dans le NIR. Cela nous a permis d’étudier la réponse en fluorescence de deux colles époxy, sources typiques de la contamination d’engin orbital et de la comparer avec une mesure obtenue avec un instrument commercial. Ces mesures nous ont permis d’évaluer les performances de notre instrument et d’identifier des perspectives d’amélioration, notamment en termes de sensibilité dans les UV
In the field of failure analysis and in particular molecular and particulate contamination, being able to detect any trace of contaminants during the integration of an orbital spacecraft is crucial. In this context, fluorescence allows not only to detect but also to discriminate contaminants. For this project, we have therefore developed a broadband hyperspectral instrument (UV-Vis-NIR) from 330 to 1000 nm to be able to detect a wide range of contaminants. It is a catoptric assembly that eliminates chromatic aberrations. The field of view is 3.5° for an angular resolution of 25 arc seconds. It was designed to be portable and its fixed mechanical assembly allows easy optical alignment and rapid creation of calibration files between two scenes. We measured a spectral resolution of 1 nm in the UV range, 2 to 3 nm in the visible range and 5 nm in the NIR range. This allowed us to study the fluorescence response of two epoxy glues, typical sources of orbital spacecraft contamination, and to compare it with a measurement obtained with a commercial instrument. These measurements allowed us to evaluate the performance of our instrument and identify prospects of improvement, especially in terms of sensitivity in UV range

Ce travail de thèse porte sur l'analyse de nanofils de ZnO dopés au cobalt par implantation ionique, en utilisant la fluorescence des rayons X, la spectroscopie d'absorption des rayons X et les techniques de diffraction des rayons X à l'échelle nanométrique sur la ligne de lumière ID22 de l'Installation Européenne de Rayonnement Synchrotron. Les nanofils sont obtenus par croissance catalysée sur des substrats de p-Si (100). Les nanofils de ZnO synthétisés ont été dopés avec du cobalt par d'implantation ionique. Pour la première fois, l'utilisation combinée des techniques de caractérisation par rayons X citées ci-dessus nous permet d'étudier l'homogénéité de la distribution des dopants, la composition, ainsi que l'ordre structurel à courte et grande distance de nanofils individuels. Les résultats de la nano-fluorescence des rayons X indiquent que le dopage au cobalt par implantation ionique dans les nanofils de ZnO est homogène, avec les concentrations désirées. La spectroscopie d'absorption de rayons X et l'analyse des données de diffraction de rayons X fournissent de nouvelles informations sur la distorsion du réseau cristallin produite par l'introduction de défauts structuraux par le processus d'implantation ionique. Ces résultats soulignent l'importance du recuit thermique après l'implantation pour récupérer la structure des nanofils de ZnO à l'échelle du nanomètre. Les mesures complémentaires de micro-photoluminescence et cathodo-luminescence corroborent ces résultats. En conclusion, les méthodes utilisées dans cette thèse ouvrent de nouvelles voies pour l'application de mesures multi-techniques basées sur le rayonnement synchrotron pour l'étude détaillée des nanofils semi-conducteurs à l'échelle nanométrique
The PhD dissertation focuses on the investigation of single Co-implanted ZnO nanowires using X-ray fluorescence, X-ray absorption spectroscopy, and X-ray diffraction techniques with nanometer resolution at the beamline ID22 of the European Synchrotron Radiation Facility. The ZnO nanowires were grown on p-Si (100) substrates using vapor-liquid-solid mechanism. The synthesized ZnO nanowires were doped with Co via an ion implantation process. For the first time, the combined use of these techniques allows us to study the dopant homogeneity, composition, short- and large-range structural order of individual nanowires. The nano-X-ray fluorescence results indicate the successful and homogeneous Co doping with the desired concentrations in the ZnO nanowires by an ion implantation process. The nano-X-ray absorption spectroscopy and X-ray diffraction data analyses provide new insights into the lattice distortions produced by the structural defect formation generated by the ion implantation process. These findings highlight the importance of the post-implantation thermal annealing to recover the structure of single ZnO nanowires at the nanometer length scale. Complementary microphotoluminescence and cathodoluminescence measurements corroborrate these results. In general, the methodologies used in this work open new avenues for the application of synchrotron based multi-techniques for detailed study of single semiconductor nanowires at the nanoscale

Doctor of Philosophy
Department of Chemical Engineering
Keith L. Hohn
Amorphous silica-alumina is widely used as a solid acid catalyst for various reactions in oil refining and the petrochemical industry. The strength and the number of the acid sites in the material are most often believed to arise from the alumina atoms inserted into the silica lattice. The existence of the acidity distribution across the framework is a result of the local composition or the short-range interactions on the silica-alumina surface. Conventional techniques used to characterize silica-alumina provide effective information on the average acidity, but may not reflect the heterogeneity of surface acidity within the material. Recently, it is possible to study individual catalytic sites on solid catalysts by single molecule fluorescence microscopy with high time and space resolution. Fluorophores can be chosen that emit at different wavelengths depending on the properties of the local environment. By doping these fluorophores into a solid matrix at nanomolar concentrations, individual probe molecules can be imaged. Valuable information can be extracted by analyzing changes in the fluorescence spectrum of the guest molecules within a host matrix. In this research, silica-alumina thin films were studied with single molecule fluorescence microscopy. The samples were prepared by a sol-gel method and a wide-field fluorescence microscope was used to locate and characterize the fluorescent behaviors of pH sensitive probes. In mesoporous thin films, the ratio of the dye emission at two wavelengths provides an effective means to sense the effective pH of the microenvironment in which each molecule resides. The goal of this work was to develop methods to quantify the acidity of individual micro-environments in heterogeneous networks. Pure silica films treated with external phosphate solutions of different pH values were used to provide references of the fluorescence signals from individual dye molecules. SM emission data were obtained from mesoporous Al-Si films as a function of Al content in films ranging from 0% to 20% alumina. Histograms of the emission ratio revealed that films became more acidic with increasing Al content. The acidity on interior surfaces in zeolite pores was also of interest in this work. A microfluidic device was built to isolate the interior surface from the exterior surface. Some preliminary results showed the potential of using SM fluorescence method to study the acidic properties inside the pores of zeolite crystals.

La lignine est un polymère polyphénolique de la paroi cellulaire qui intervient dans de nombreux aspects de la croissance et du développement des plantes supérieures. En tant que composant majeur de la biomasse lignocellulosique, elle présente également un intérêt économique. Bien que la biosynthèse du polymère de la lignine soit relativement bien comprise, nous avons besoin d'en savoir plus sur la façon dont les changements (quantité/structure) des autres polymères de la paroi cellulaire (par exemple, la cellulose, les hémicelluloses, les pectines) affectent la production de lignine. Afin de fournir plus d'informations sur cette question, nous avons mis en œuvre une approche en deux phases basée sur l'utilisation de l'imagerie biologique. La première phase a consisté à développer/améliorer différentes techniques d'imagerie complémentaires à haute résolution. Nous avons tout d'abord développé une nouvelle approche ratiométrique quantitative (REPRISAL) basée sur la segmentation paramétrique/intelligence artificielle d'images de microscopie confocale obtenues par la chimie bio-orthogonale des rapporteurs chimiques de la lignine (click chemistry). Cette méthodologie nous a permis de cartographier précisément la capacité de lignification des différentes couches de la paroi cellulaire (coin cellulaire, lamelle moyenne composée et paroi cellulaire secondaire) chez les plantes Arabidopsis WT et le mutant prx64. Dans un deuxième temps, nous avons modifié l'algorithme de segmentation REPRISAL afin de pouvoir l'utiliser pour cartographier les niveaux relatifs de lignine de la paroi cellulaire déterminés par la technique de fluorescence ratiométrique de la safranine-O. Enfin, nous avons utilisé l'imagerie Raman pour comparer la capacité de trois méthodes analytiques multivariées différentes (non-mixage, analyse en grappes et correspondance orthogonale) à fournir des informations spatiales détaillées sur la distribution des différents polymères dans les parois cellulaires des plantes. Dans la deuxième phase, nous avons utilisé les techniques d'imagerie développées/améliorées pour analyser si les modifications des hémicelluloses de la paroi cellulaire affectent la lignification chez le mutant irx9 d'Arabidopsis. Nos résultats ont démontré que les changements dans la distribution des hémicelluloses de la paroi cellulaire modifient effectivement le processus de lignification, en particulier dans les parties les plus jeunes de la tige florale de la plante. La transcriptomique ciblée de certains gènes de la paroi cellulaire suggère que les changements observés pourraient être liés à l'induction d'une réponse de défense. Globalement, les techniques développées dans le cadre de cette thèse devraient s'avérer précieuses pour les études futures de la dynamique des parois cellulaires. Les résultats obtenus sur le mutant irx9 donnent un nouvel aperçu des relations dynamiques qui existent entre les différents polymères de la paroi cellulaire des plantes
Lignin is a polyphenolic polymer of the cell wall involved in many aspects of growth and development in higher plants. As a major component of lignocellulosic biomass, it is also of economic interest. Although the biosynthesis of the lignin polymer is relatively well understood, we need to know more about how changes (quantity/structure) to other cell wall polymers (e.g., cellulose, hemicelluloses, pectins) affect lignin production. To provide more information on this question we implemented a two-phase approach based on the use of biological imaging. The first phase involved the development/improvement of different high-resolution complementary imaging techniques. We firstly developed a novel quantitative ratiometric approach (REPRISAL) based on the parametric/artificial intelligence segmentation of confocal microscopy images obtained by lignin chemical reporter bio-orthogonal chemistry. This methodology allowed us to precisely map the lignification capacity of different cell wall layers (cell corner, compound middle lamella and secondary cell wall) in Arabidopsis WT plants and the prx64 mutant. In a second development, we modified the REPRISAL segmentation algorithim thereby enabling it to be used to map relative cell wall lignin levels determined by the ratiometric safranin-O fluorescence technique. Finally, we used Raman imaging to compare the ability of three different multivariate analytical methods (unmixing, cluster analysis and orthogonal matching) to provide detailed spatial information about the distribution of different polymers in plant cell walls. In the second phase we used the developed/improved imaging techniques to analyse whether changes to cell wall hemicelluloses affect lignification in the Arabidopsis irx9 mutant. Our results demonstrated that changes in the distribution of cell wall hemicelluloses do indeed modify the lignification process, particularly in the younger parts of the plant floral stem. Targeted transcriptomics of selected cell wall genes suggested that the observed changes could be related to the induction of a defence response. Overall, the techniques developed within the framework of this thesis should prove valuable for future studies of cell wall dynamics. The results obtained on the irx9 mutant provide a novel insight into the dynamic relationships that exist between different polymers of the plant cell wall

The insular nature of the Maltese archipelago provides a unique opportunity to explore trade and cultural change from the Neolithic to the Bronze Ages in the central Mediterranean. I hypothesize that, during the period in which the Maltese islands were experiencing a form of isolation—owing either to their distance from Sicily and other populated regions, to the collective formation of an inwardly-focused culture, or to a combination of these factors—it is unlikely that pottery played a significant role as either an import or export in the archipelago’s exchange relationships with other communities in the central Mediterranean. I accordingly propose that ceramics were only significant in the interaction networks between Malta and its neighbors during periods when the archipelago was culturally connected to Sicily. Except for a limited number of archaeometric studies (Barone et al. 2015; Molitor 1988; Mommsen et al. 2006), analysis of similarities among ceramic wares produced in Malta and elsewhere that allow archaeologists to draw conclusions about the nature of Malta’s connectivity to other communities has been based on macroscopic observation. The present study builds on the few archaeometric studies by determining the provenance of ceramic samples based on their trace elemental composition. Included in this study were both clay samples and ceramic artifacts representing each of Malta’s chronological phases from the Neolithic to the Bronze Ages. Specifically, in order to address the question of the role that pottery played in the prehistoric trade of the Maltese islands, 392 Maltese ceramic sherds were analyzed using a Bruker III-V handheld portable X-ray fluorescence device, which revealed the relative abundance of six trace elements, namely thorium, rubidium, strontium, yttrium, zirconium, and niobium. The trace elemental composition of the Maltese pottery was compared with that of 18 Sicilian ceramic sherds and clay samples from both Malta and Sicily. The results of this research support my hypothesis in part, suggesting that neither ceramics nor raw clay materials played a significant role in overseas trade during Malta’s period of cultural isolation, which extended from the Ġgantija phase to the end of the Tarxien phase. On the other hand, ceramics played a more active role in Malta’s interaction networks during periods of connectivity with Sicily, for instance in the Neolithic Age. This study also provides the first chemical evidence that Malta exported pottery to Sicily during the Bronze Age and that Malta’s contact with Mycenaeans was indirect in nature. The findings presented here thus contribute to understanding Malta’s role in trade and interaction networks from the Neolithic to the Bronze Ages and point to new approaches to exploring the cultural change that becomes apparent in the Maltese Temple Period.

Les processus de combustion ont un impact important sur la qualité de l’air, le climat ou l’utilisation des sources d’énergie. Malgré les progrès réalisés pour une combustion plus propre, les chemins réactionnels conduisant à la formation des polluants (notamment des particules de suie) ne sont pas encore complétement élucidés. L’objectif de ce travail est d’étudier la formation des suies et de leurs précurseurs dans des flammes de laboratoire pour une meilleure compréhension fondamentale des mécanismes impliqués dans la transition de la phase gaz à la phase particulaire. Le même objectif est poursuivi dans des campagnes de terrain pour évaluer l’impact potentiel des propriétés de surface des suies sur l’environnement. Nous utilisons des techniques d’analyse in-situ (incandescence et fluorescence induites par laser) et ex-situ (spectrométrie de masse couplée à la désorption laser ou ionique) pour mettre en évidence des propriétés spécifiques des suies et de leurs précurseurs. L’évolution de l’indice de réfraction complexe avec le stade de la combustion est mesurée, et ses implications sur la physico-chimie de la flamme et sur les techniques analytiques sont discutées. Une nouvelle méthode de détection basée sur l’excitation simultanée de la suie et des précurseurs à une seule longueur d’onde est proposée. La composition chimique de surface des suies émises par des moteurs utilisés dans les transports terrestres et aériens est également analysée. Des méthodes statistiques multivariées sont utilisées pour identifier des tendances communes et des différences dans les échantillons étudiés, en faisant ressortir l’influence du carburant ou des paramètres de combustion
Combustion impacts many important aspects of our life like the air quality, the local and global climate and the use of energy sources. In the last decades, an outstanding progress towards cleaner combustion has been achieved. However, the reaction pathways leading to the formation of some pollutants, especially particulate matter (soot) resulting from incomplete combustion, are still elusive. In this work, we aim to investigate specific aspects of soot and its precursors formation in laboratory flames for a fundamental understanding of the mechanisms leading from the gas phase up to the mature particulate found in the exhausts. This objective is also pursued in field-campaigns to assess the potential impact of soot surface properties on the environment. Following this approach, experimental techniques like in-situ laser induced incandescence and fluorescence, and ex-situ laser desorption and secondary ion mass spectrometry are used to target specific properties of soot and its precursors. Notably, the evolution of the complex refractive index of soot is measured as a function of soot maturity, and the implications on both the flame physico-chemistry and the analytical techniques applicability are discussed. Additionally, a new detection method for soot and precursors based on simultaneous excitation at one wavelength is developed. In parallel, two campaigns are dedicated to the analysis of the surface chemistry of soot sampled from airplane and car exhausts. Statistical methods as multivariate analysis are used to identify patterns and differences within sets of samples by assessing the influence of the combustion parameters or the role of the fuel

The aim of the present work was to contribute to establish robust and high throughput methodology of interest in the "Drug Discovery" step commonly done in pharmaceutical laboratories. This purpose involves the exploration of the possibilities of the potentiometric Sirius methodology to determine both acidity constants and solubilities of drugs and other bioactive compounds and also to do a study about how to improve bioavailability of a model drug, Amphotericine 8, by increasing its dissolution rate. In the first part of this project, the acidic dissociation enthalpies and constants of anilinium, protonated tris (hydroxymethyl)- aminomethane (HTris+), benzoic and acetic acids, have been determined at several temperatures in pure water and in methanol/water mixtures by potentiometry method. The pK(a) values determined by this technique are in accordance with those values determined by ITC method in our laboratory and also with those other values from literature. Also dissociation enthalpies can be obtained from potentiometric pK(a) values by means of the Van't Hoff approach and these obtained values are in agreement with those ones determined directly by calorimetry in our laboratory. In the second part, we focused on studying about solubility. The Chasing Equilibrium method offers an alternative to the classical procedures to measure the solubility of compounds with acid-base properties. The method is fast and yields accurate results. In this work, the solubility of several compounds including acids and bases was determined through the Chasing Equilibrium approach. A study of experimental conditions in terms of sample weight was performed to measure solubilities. The study shows that only a limited range of weights, depending on the nature and solubility of the compounds, is adequate to obtain reliable results. In the third part of this work, the solubility vs. pH profiles of five ionizable drugs of different nature (a monoprotic acid, a monoprotic base, a diprotic base and two amphoteric compounds showing a zwitterionic species each one) have been determined through two different methodologies: the classical Shake-Flask (S-F) and the potentiometric Cheqsol methods using in both instances the appropriate Henderson-Hasselbalch (H-H) or derived relationships. The results obtained independently from both approaches are consistent. A critical revision about the influence of the electrolyte used as buffering agent in the S-F method on the obtained solubility values is also performed. Thus, some deviations of the experimental points with respect the H-H profiles can be attributed to specific interactions between the buffering electrolyte and the drug due to the hydrotrophic character of citric and lactic acids. In other cases, the observed deviations are independent of the buffers used since they are caused by the formation of new species such as drug aggregates (cefadroxil) or the precipitation of a salt from a cationic species of the analysed compound (quetiapine). In the forth part, the objective was to compare the dissolution behavior of tablets prepared from solid dispersions prepared in DMSO dissolvent with and without drug-carrier and also with and without surfactants in aqueous and acidic solutions. Amphotericine B was used as a model drug. Two types of carriers were used; mannitol, inulin. Solid dispersions with two different drug loads were prepared by freeze drying method. It was found that the drug dissolution rate in aqueous and acidic solutions was significantly increased in the presence of drug-carrier and surfactants. X-ray powder diffraction revealed that all solid dispersions were fully amorphous.
El objetivo del presente trabajo ha sido contribuir a establecer metodología robusta y de high throughput de interés en la etapa conocida como "Drug Discovery" que tiene lugar en los laboratorios farmacéuticos al inicio del proceso de desarrollo de nuevos fármacos. Este objetivo ha implicado la exploración de las posibilidades de la metodología potenciométrica establecida y comercializada por Sirius Analytical Ltd. para la determinación de las constantes de acidez y de la solubilidad de compuestos bioactivos y también un estudio sobre la mejora de la biodisponibilidad de un fármaco muy insoluble tomado como modelo mediante el aumento de su velocidad de disolución. En la primera parte de esta Tesis se han determinado potenciométricamente las constantes de disociación ácida y la variación de entalpía asociada de dos bases y dos ácidos tomados como modelo en agua pura y en mezclas de metanol/agua (0-60% w/w) a varias temperaturas (25-55°C). Esto ha implicado la puesta a punto de la estandarización del sistema potenciométrico en las condiciones de trabajo. Los valores de pK(a) determinados son concordantes con los que ofrece la literatura. Se han calculado también las entalpias de disociación en los distintos solventes binarios estudiados mediante la ecuación de Van't Hoff a partir de los valores experimentales de pK(a). La consistencia de los resultados obtenidos con los de la literatura, obtenidos directamente por calorimetría, confirma la robustez de la metodología. En la segunda parte de este trabajo, el estudio se centró sobre la determinación potenciométrica de la solubilidad de ácidos y bases mediante el método conocido como Chasing Equilibrium, como alternativa a los procedimientos clásicos de equilibración. El método es rápido y produce resultados precisos. Se ha realizado un estudio sobre las condiciones experimentales óptimas en términos de peso de la muestra para medir eficazmente la solubilidad. El estudio muestra que, en función de la naturaleza y solubilidad de los compuestos, existe un intervalo limitado de peso de muestra adecuado para obtener resultados fiables. En la tercera parte de la presente memoria, se estudian los perfiles de solubilidad en función del pH de cinco fármacos ionizables de naturaleza diferente, un ácido y una base monopróticos, una base diprótica y dos compuestos anfóteros que muestran una especie zwitteriónica cada uno. Se han determinado los perfiles de solubilidad mediante el método clásico de equilibración (Shake-Flak, S-F) y el potenciómétrico y, en ambos casos, se han utilizado las relaciones apropiadas de Henderson-Hasselbalch (H-H) o derivadas. Los resultados obtenidos de forma independiente por ambos métodos son consistentes. Se ha hecho un estudio crítico acerca de la influencia del electrolito utilizado como agente tampón en el método S-F en los valores de solubilidad obtenidos y se han observado algunas desviaciones de los puntos experimentales con respecto a los perfiles esperados que pueden ser debidas a interacciones específicas entre el electrolito tampón y el fármaco. En otros casos, las desviaciones observadas son independientes de los tampones utilizados y se pueden atribuir a la formación de nuevas especies tales como agregados iónicos del fármaco en estudio o la precipitación de una sal a partir de una especie catiónica del compuesto analizado. En la cuarta parte de esta memoria el objetivo ha sido estudiar la velocidad de disolución de comprimidos preparados a partir de dispersiones sólidas de un fármaco modelo con y sin portador del fármaco y también en presencia y en ausencia de tensioactivo en soluciones acuosas neutras y ácidas. Como fármaco modelo se estudió la Anfotericina B y se utilizaron como portadores manitol e inulina y como tensioactivos se ensayaron el deoxicolato de sodio (SDC) y el laurilsulfato de sodio (SLS). La difracción de rayos X reveló que el fármaco en estudio se hallaba en estado amorfo en todas las dispersiones sólidas estudiadas. Se puede concluir que la velocidad de disolución del fármaco se incrementa significativamente en presencia de portador y tensioactivo.

La tesi esplora le correlazioni fra composizione chimica del particolato emesso in frenata e alcuni fattori quali: i) le combinazioni di materiali che compongono l'interfaccia tribologica; ii) le condizioni di guida; iii) le frazioni dimensionali in cui vengono prodotti i particolati
This thesis reports on the correlations between the compositional features of the particulates produced by brakes and several determining or modulating factors, such as: i) The starting material composing the friction couple; ii) the driving conditions; and iii) the dimensional fractions in which the particulates are generated and emitted.

L'ampio utilizzo di nanomateriali ingegnerizzati (ENM) in svariati prodotti sta suscitando una crescente attenzione sull potenziale rischio di ENM nei confronti della salute umana e l'ambiente. Nonostante le indagini tossicologiche fin qui condotte, solo in poche di esse è stata condotta la caratterizzazione di ENM prima, durante e dopo i test tossicologici. In questa tesi, all’interno del progetto europeo EU-FP7 (ENPRA) e nazionale (PRIN 2009), è stata effettuata una caratterizzazione completa di alcuni più diffusi ENM (i.e. n-TiO2, n-ZnO, n-Ag e MWCNT). In primo luogo, sono stati aggiornati i dati di caratterizzazione primaria con ulteriori analisi; inoltre, è stata effettuata la caratterizzazione secondaria di ENM, indagando il loro comportamento in matrici ambientali. I risultati ottenuti mostrano che la stabilità di ENM è stata principalmente influenzata da agenti stabilizzanti (in mezzi biologici) e dalla concentrazione iniziale di ENM (in acque sia artificiali e reali). Inoltre, la biodistribuzione di ENM negli organi studiati è stata maggiormente influenzata dalla composizione chimica e dimensione delle particelle indagate. Sono discussi sia l'approccio di caratterizzazione proposto che l'implicazione dei risultati ottenuti.
The extensive use of engineered nanomaterials (ENM) in both industrial and consumer products is triggering a growing attention on the potential risk of ENM posed to human health and the environment. Despite the intensive toxicological investigations, both in vitro and in vivo, only few of them have embedded a solid characterization approach, including the study of ENM before, during and after toxicological testing. Within EU-FP7 (ENPRA) and national (Toxicological and environmental behaviour of nano-sized titanium dioxide) projects activities, a comprehensive characterization of both inorganic (n-TiO2, n-ZnO, n-Ag) and organic (multiwalled carbon nanotubes, MWCNT) ENM was carried out, updating and adding primary characterization data, investigating particle size, shape, crystallite size, crystalline phases, specific surface area, pore volume as well as inorganic impurities of concern. Electron microscopy, X-ray diffraction, BET method and Inductively coupled plasma- mass spectrometry or optical spectroscopy were the employed techniques. With regard to the secondary characterization of ENM, the study was divided in: (a) assessing the engineered nanoparticles (ENP) behavior in biological (0.256 mg ENP/ml) as well as in real and synthetic waters (environmentally realistic concentrations: 0.01, 0.1, 1 and 10 mg n-TiO2 P25/l) over different time interval (24 h in biological media instead of 50 h in water media) to mimic duration of toxicological tests, by means of Dynamic Light Scattering (DLS), analytical centrifugation and nephelometry; (b) evaluating the ENM biodistribution in a secondary target organ (i.e. mice brain) after intratracheally instillation of ENM (0, 1, 4, 8, 16, 32, 64 and 128 ug ENM/animal tested), achieved by a microwave-assisted digestion method, followed by ICP-MS analysis, after selecting inorganic elements (i.e. Ti, Zn, Ag, Al and Co) as tracers of ENM presence in biological tissues. To investigate the ENP behavior in biological media and ENM biodistribution in mice, both dispersion protocols of the selected ENP and analytical protocols for ENM detection after toxicological testing were provided. The study of ENP stability in biological media highlighted that the fetal bovine serum (FBS) is the main parameter affected the ENP behavior. Among biological media tested, the largest size distributions, immediately after sample preparation, were irecorded for n-TiO2 NRCWE-003 dispersions. n-ZnO NM-111 dispersions were the most stable (12% average demixing, simulating 24 h of real sedimentation), except for Ag NM-300, originally received as dispersion (<1% average demixing). As expected, the ENP sedimentation rates investigated in the biological medium without any stabilizer (i.e. RPMI), were the highest for the whole set of ENP tested. In general, the highest sedimentation rates were recorded for n-TiO2 NM-101 and n-Ag 47MN-03 dispersions (51% average demixing, simulating 24 h of real sedimentation). The study of the n-TiO2 P25 stability in waters showed that agglomeration and sedimentation of n-TiO2 were mainly affected by the initial concentration. Sedimentation data fitted satisfactorily (R2 average: 0.90; 0.740.98) with a first- order kinetic equation. The settling rate constant, k, increased by approx. one order of magnitude by moving from the lowest to the highest concentration, resulting very similar especially for all dispersions at 1 (k = 8•10-6 s-1) and 10 mg/l (k = 2•10-5 s-1) n- TiO2, regardless the ionic strength and composition of dispersions. The results from ENM biodistribution underlined that the chemical composition and the particle size were the main parameters that influenced the ENM partitioning into organs. Ti from n-TiO2 samples with the smallest particle size distribution tested (80-400 nm and 4-100 nm) and Al from MWCNT samples were the only inorganic tracers detected in mice brain. The whole characterization approach and the implication of these results are discussed.

Cold Atmospheric pressure Plasmas (CAP) generated by Dielectric Barrier Discharges (DBDs) are being studied and developed for an ever-widening range of applications in both biomedical and industrial areas. In particular surface DBDs (SDBDs), consisting of a planar powered electrode separated from a grounded mesh by a thin dielectric layer, have been gaining great interest for their ability to produce highly reactive atmospheres at close-to-environmental temperature and almost independent from the electrical properties of the target, which is treated in the afterglow of the surface plasma. The active chemistry initiated in the afterglow of SDBDs operated in air is characterized by the presence of long-lived reactive oxygen and nitrogen species such as O3, NOx and HNOx, which are recognized to play an important role in many industrial and biomedical applications based on the use of the plasma afterglow. Knowing the kinetics of all the chemical species produced in the plasma and in its afterglow is then fundamental to control and optimize the processes for which SDBDs are being used. This project focuses on the physico-chemical characterization of a SDBD plasma source developed by the research group in Industrial Application of Plasmas (AIP - DIN - Alma Mater Studiorum), supplied with a high voltage AC generator with tunable frequency and duty cycle. First a study of the surface power density (SPD) variation as a function of voltage, frequency and duty cycle was made. Then the kinetics of O3/NO2/NO3 concentrations in the plasma afterglow were studied by means of OAS measurements. This project’s main aim is to gather additional knowledge on the kinetics of the produced reactive species, comparing the results with the ones from other works from literature, providing additional evidence about SPD being the driving parameter for plasma afteglow kinetics. A second aim is to provide a set of data that can be used as input and validation for future modelling tools.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T09:14:09Z No. of bitstreams: 0
Made available in DSpace on 2016-11-11T09:14:09Z (GMT). No. of bitstreams: 0
A quitina é o principal produto obtido do processamento das cascas de crustáceos. Esse biopolímero e o seu derivado, quitosana, têm despertado grande interesse comercial em virtude das possibilidades de aplicações que possuem. O gerenciamento desses resíduos e dos subprodutos gerados nas etapas no processo de obtenção pode ser considerado um modelo de biorrefinaria. A implementação de plantas para extração de quitina e quitosana é um desafio, uma vez que a demanda produtiva deve ser atendida sem causar danos ao meio ambiente. Uma grande variedade de quitosanas com diferentes propriedades físicoquímicas podem ser obtidas variando-se as condições de reação. Essas propriedades dependem da origem da matéria-prima, do seu grau médio de desacetilação, distribuição média dos grupos acetil ao longo da cadeia principal e da sua massa molecular média. Os fornecedores de quitosana comercial geralmente não mencionam a procedência da matéria-prima e pouca ou nenhuma informação é fornecida acerca do seu processamento. Sendo assim, as características e a reatividade do produto final podem variar gerando resultados não reprodutíveis. No presente estudo, foi utilizada a biomassa oriunda de rejeitos da indústria pesqueira de camarão da região de Cananéia SP. As amostras de - quitina foram obtidas por dois procedimentos diferentes: no primeiro, P1, as cascas de camarão após passar pelo pré-tratamento (lavagem, secagem e moagem) foram desproteinizadas para retirada das proteínas em hidróxido de sódio (NaOH) diluído nas concentrações 2%, 5% e 10% e desmineralizadas em ácido clorídrico (HCl) a 20% (v/v) para retirada dos carbonatos; no segundo procedimento, P2, essas etapas foram invertidas. A biomassa resultante foi desacetilada com hidróxido de sódio concentrado a 30%, 40% e 50% em tempos que variaram de 2 a 6 horas. As principais propriedades físico-químicas das amostras de quitosanas obtidas foram determinadas utilizando a espectroscopia na região do infravermelho com transformada de Fourier (FT-IR) para a determinação do grau médio de acetilação, GA, e a técnica de titulação ácido-base mensurada por condutimetria foi utilizada para comparar os resultados; a viscosimetria capilar para a determinação da massa molar média viscosimétrica, Mv , e a difração de raios X (DRX) para avaliar o grau médio de cristalinidade, X. Além disso, foram empregadas as técnicas de microscopia eletrônica de varredura (MEV) para análises morfológicas dos materiais obtidos e a espectrometria de fluorescência de raios X por dispersão de comprimento de onda (WDXRF) para análise química das quitosanas. O GA e o X das amostras diminuíram à medida em que o tratamento se tornou mais vigoroso, enquanto a Mv aumentou. O procedimento 2 foi o mais viável por eliminar a etapa de despigmentação, pois originou amostras com tonalidade mais clara e fáceis de pulverizar.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

The aim of this research was, on the one hand, the investigation of two paintings using a mobile scanning macro-XRF systems (MA-XRF) while, on the other hand, a chemical-physical characterization of smalt, a blue potash glass pigment containing cobalt that is present in the two paintings,, was carried out. For this purpose, scanning electron microscopy coupled to an energy dispersive X-Ray spectrometer (SEM-EDS) and X-ray absorption near-edge spectroscopy with synchrotron radiation as source (SR-XANES) measurements were performed. Two paintings, Ritratto di Michelangelo attributed to S. del Piombo (1485-1547) and The Education of Mary painted by P.P. Rubens (1577-1640), were analyzed using a mobile scanning macro-XRF instrument (MA-XRF). The first painting revealed the presence of an underpainting representing Mary with Child and, possibly, young St. John. This underpainting has a strong resemblance to a work of art by Andrea del Sarto (1486-1530), Madonna and Child with the Young St John, supporting in a significantly new manner hypothesis about the already difficult attribution of the painting to del Piombo. A digital imaging reconstruction based on the elemental maps allowed to clearly visualize the hidden painting and, to some extent, to give an idea of its original colors. In a very convincing manner the reconstruction highlights the similarity between the covered painting and the work of del Sarto. The analyses on the Rubens painting helped in the identification of the pigments used by the artist and in the visualization of the original shape of Mary’s scarf, painted with (now discolored) smalt. A few samples were taken from each of the paintings to characterize in greater detail the smalt grains, present in Mary’s hidden dress in Ritratto di Michelangelo and in Mary’s scarf in The Education of Mary. This pigment, a blue potash glass containing cobalt, has a complex degradation process, that involves the leaching out of potassium from the silica matrix, the consequent change of coordination of Co2+ from tetrahedral (blue) to octahedral (discolored), and the formation of carboxylates soaps between the potassium and the oil (medium), giving rise to a brownish-gray appearance of the paint layer. Due to its conservation problems, smalt is a well-studied pigment. Nevertheless, many elements are present in the pigment as impurities and their role in the degradation process has not been considered previously. In order to supply to this lack of knowledge, a number of scanning electron microscopy energy dispersive X-Ray spectrometry (SEM-EDS) measurements were carried out. For comparative purposes, other historic paint samples containing smalt were analyzed as well. These samples come from different works of art belonging to different periods and provenances. An interesting phenomenon was observed during the analysis: sometimes a lead-enriched rim is present in the degraded smalt grains. This points to an interaction between the silica matrix and the lead ions, coming from the environment (lead white) or present inside the grains, has occurred. The interpretation of the results was possible thanks to a chemometrical analysis on the quantified EDS spectra, allowing to understand the correlation between the smalt composition and its degradation. Moreover, synchrotron radiation X-ray absorption near-edge spectroscopy (SR-XANES) measurements were performed on both degraded and well preserved smalt, to certify the change in the coordination of Co2+ due to the leaching out of potassium, and trying to better understand the phenomenon of lead-enriched rim formation.

Since ancient times glass was used as storage material for ointments, medicinal remedies and cosmetics for its properties of inertness and product protection. Along the centuries the technology has developed dedicated glasses for pharmaceutical use, improving their mechanical and chemical performances up to the modern borosilicate glasses. Meanwhile the technology is trying to meet the needs of new complex and sensitive drugs, the necessity of new analytical approaches has increased for a better overview of the content-material interactions to complement the classical pharmacopoeia analysis. From this perspective a physico-chemical analytical approach, focused on the glass surface as main player of the drug-content interactions, is the main topic of this study. The application of surface dedicated complementary techniques as XPS, SIMS and SEM was investigated, permitting the characterization of the glass surface in terms of morphology, composition and depth elemental overview. As preliminary part of a more complex project, this study focused on the comparison and baseline characterization of the raw materials with the related finished containers, highlighting interesting surface features and glass composition-related peculiarities. This work confirms the suitability of these analytical techniques to pave the way for further studies on long term storage or environmental effects, helping to define a possible correlation with drug interactions phenomena.

L'intérêt pour les biocarburants s’est considérablement accru ces dernières années car ceux-ci pourraient permettre de diminuer la dépendance aux combustibles fossiles et contribuer à une croissance neutre en carbone. L’influence de l’utilisation de biocarburants sur les émissions de polluants (CO,CO_2,NO_x,HC, etc.) a fait l’objet de nombreux travaux, cependant les effets de la nature de ces carburants alternatifs sur les propriétés physico-chimiques des particules et des espèces aromatiques produites sont encore peu étudiés. Dans le cadre de ce travail de thèse, nous visons à caractériser les émissions de particules de suie et d'hydrocarbures aromatiques polycycliques (HAP) lors de la combustion de carburants conventionnels et alternatifs (biocarburants) pertinents pour les secteurs de l'automobile et de l'aéronautique, tout en essayant de mettre en lumière leurs influence sur les mécanismes de formation de ces polluants. Pour atteindre cet objectif, deux réacteurs de laboratoire, un bruleur turbulent swirlé et un Combustion Aerosol STandard (CAST), ont été utilisés comme générateurs de suie. De plus, nous avons combiné différentes techniques laser complémentaires in situ, les incandescence et fluorescence induites par laser (LII/LIF), et ex situ, la spectrométrie de masse après désorption et ionisation laser (L2MS) et la spectrométrie de masse des ions secondaires (SIMS). Dans une flamme turbulente swirlée pour cinq carburants (Diesel, n-butanol, mélange 50/50 Diesel/n-butanol, Jet A1 et Synthetic Paraffinic Kerosene SPK), les profils LII et LIF et les propriétés des particules de suie et de leurs précurseurs en fonction de la hauteur dans la flamme ainsi que leur composition chimique ont été étudiés. De fortes corrélations entre les résultats obtenus avec les techniques in situ et ex situ ont été mises en évidence permettant de caractériser spectralement et chimiquement ces espèces. En outre, une nouvelle méthode d'étalonnage a été développée pour déduire directement la fraction volumique de suie à partir du signal LII en utilisant la luminance énergétique absolue émise par une source ayant un rayonnement de corps noir. En parallèle, les expériences utilisant le dispositif CAST ont été menées avec les carburants aéronautiques (Jet A1 et SPK). Outre l'influence du carburant de substitution, les effets d’un stripper catalytique (CS) sur les particules de suie et les espèces volatiles ont été examinés
Interest in biofuels has increased significantly in recent years as they could reduce dependence on fossil fuels and contribute to carbon-neutral growth. The influence of using biofuels on their exhaust emissions (CO,CO_2,NO_x,HC, etc.) has been studied widely. However, the effects of the nature of these alternative fuels on the physical and chemical properties of the particles and aromatic species produced are not fully understood. As part of this thesis work, we aim to study the emissions of soot particles and polycyclic aromatic hydrocarbons (PAHs) during the combustion of conventional and alternative fuels (biofuels) relevant to the automotive and aerospace sectors, while trying to highlight their influence on the formation of such pollutants. To achieve this goal, two laboratory combustors, a swirled turbulent jet burner and a Combustion Aerosol STandard (CAST), were used as soot generators. In addition, we have combined various complementary in-situ laser techniques, laser-induced incandescence and fluorescence (LII/LIF), and ex-situ two-step laser mass spectrometry (L2MS) and secondary ion mass spectrometry (SIMS). In a swirled turbulent jet flame for five fuels (Diesel, n-butanol, 50/50 Diesel/n-butanol mixture, Jet A1 and Synthetic Paraffinic Kerosene SPK), the LII and LIF profiles and properties of soot particles and their precursors with the height in the flame as well as their chemical composition were studied. Strong correlations between the results obtained with in-situ and ex-situ techniques have been demonstrated which allowed us to characterize these species spectrally and chemically. In addition, a new calibration method has been developed to directly deduce the soot volume fraction from the LII signal using the absolute radiance emitted from a light source having black body behavior. In parallel, experiments using the CAST device were conducted with aeronautical fuels (Jet A1 and SPK). In addition to the influence of the alternative fuel, the effects of a catalytic stripper (CS) on soot particles and volatile species were examined

The aim of this PhD thesis is the development of new metodologies for surface anchoring of molecular and supramolecular systems for applications in molecular electronics and photonics, and for preparation of devices for molecular recognition. The systems are made up, as usually, of hybrid systems, divided in two parts, a molecular one and a solid support. The molecular part performs the desired function, while the solid support (metal or semiconductor on which the molecules are bound) allows to conjunct its properties with molecular system properties and, moreover, to help the correct orientation of the molecules at the surface. Such systems were compositionally and structurally characterized by means of surface analysis techniques, as time of flight of secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). The nodal point of this research work, so, is surface functionalization. Many kind of surface were used, in particular oxides like silicon oxide and quartz (as model systems), transparent semiconductor oxides like indium tin oxide (ITO), and metal surfaces like gold. Such surfaces were functionalized by means of a bottom up approach, in particular the formation of a self-assembled monolayer (SAM), based on the chemisorpion of molecules bearing suitable functional groups. For oxide surfaces, molecules for SAM formation were characterized by a phosphonate as surface active group, able to form monolayer exploiting zirconium-phosphate-phosphonate (ZP) chemistry. For gold surface, instead, the surface active group was a thiol. Functional molecules adopted for this purpose, bear a terpyridine group as tail. Such ligand was chosen because the chelant moiety 2,2 :6 ,2 -terpyridine (Tpy) is one of the most exploited because of the very high affinity for bivalent metal ions, and the ability to form stereospecific, achiral, and octhaedrical complexes. Mono- and bis-terpyridine based metal ion complexes were prepared in order to obtain, by means of a step-wise approach, multilayer systems that can be seen as assembled molecular wires. In particular conjucated polyphenilenic ligands properties were exploited. Moreover, great efforts were made in order to obtain systems for the construction of devices for molecular recognition. With this aim, attention was focused on gold surface funtionalization to anchor on it, on one hand oligonucleotides chains, on the other hand, supramolecular systems called pseudo-rotaxanes . Oligonucleotide sequences anchoring was carried out in order to have information about the possibility that probe and targed oligonucleotides chains could react depending on them complementarity, studing this process by hybridization directly in situ. Pseudo-rotaxanes assembly, was very interesting because it was possible, for the first time, to carry out complexation of molecular building blocks (host and guest) directly on surface, instead of in solution.

This thesis is divided into two projects. The first project investigates the dissolution of the Hanford salt cakes, the chemical properties of the effluent and the physical properties such as viscosity of the effluent, the porosity and the permeability of the salt cake bed as the dissolution proceeds. The chemical results are compared to predictions using a thermodynamic model. Physical properties are important because they govern the rate at which the Hanford tanks can be emptied thus facilitating the remediation process. Two simulants were investigated for the dissolution process. The chemical analysis matched with the model predictions for both the simulants. A typical gibbsite layer formation was observed in the chemically complex simulant and experiments were performed to remediate the layer. The second project of this thesis studied the remediation of sodium phosphate dodecahydrate plug using water and sodium carbonate solutions at varying concentrations. A flow loop previously used to study the sodium phosphate dodecahydrate plugging mechanisms, was used to form a plug followed by the addition of water and sodium carbonate solutions. Results indicate that there was a drastic decrease in time to remediate the plug when sodium carbonate solutions were used.

Anion recognition is a topical area of research warranted by the potential applications of anion receptors in environmental and biological monitoring. Anions are indeed widespread in nature, are involved in many biochemical processes and are also major aqueous pollutants. Molecular receptors able to recognize anions with high affinity and selectivity in organic solvents are well documented in the literature but only few systems are efficient in aqueous media. Water is undeniably a particularly challenging solvent to work with due to the competition of water in the recognition process. Moreover, most of the receptors that are known to bind anions with high affinity and selectivity in organic solvents are not soluble in water. One strategy used to make hydrophobic molecular receptors “water-compatible” is micellar incorporation. This strategy is straightforward as no synthetic modifications of the receptor are required and has furthermore been seen to enhance the apparent properties, in particular binding properties, of the receptors. Following previous work undertaken in the laboratory, this thesis was devoted to the study of the micellar incorporation of different anion receptors. The first part of this thesis focused on the potential of Nuclear Magnetic Resonance (NMR) and more precisely Paramagnetic Relaxation Enhancement (PRE) experiments to provide robust information on the localisation of receptors within micelles. We studied the effect of various parameters and were able to rationalize the effect of the nature and concentration of the counterion and of the surfactant concentration on the PRE values obtained with cationic cetyltrimetylammonium (CTAX) micelles. By applying a normalization procedure we were then able to compare different receptor/micelle systems. This work has been reported in the Journal of Physical Chemistry (“Paramagnetic Relaxation Enhancement Experiments: a Valuable Tool for the Characterization of Micellar Nanodevices”, F. Keymeulen, P. De Bernardin, A. Dalla Cort, and K. Bartik, J. Phys. Chem. B, 2013, 117, 11654–11659).The second part of our work consisted in the study of the role played by the surfactant on the efficiency of the supramolecular system formed. Using UV-vis and/or NMR titrations, we studied the impact of the nature of the surfactant (cationic, zwitterionic or neutral) as well as its concentration on the apparent binding affinity for fluoride of two uranyl-salophen receptors. We showed that the supramolecular systems formed with cationic micelles are the most efficient, due to the favourable electrostatic interaction between the positively charged micelle and the fluoride despite the competition of the surfactant counter-ion. The concentration of the cationic surfactant does however have an impact as the apparent affinity decreases with surfactant concentration as a consequence of this non-specific interaction of the guest with the micelles. PRE and DLS (Dynamic Light Scattering) experiments allowed us to better understand the differences between the different types of micelles. This work has been reported in Organic & Biomolecular Chemistry (“Fluoride binding in water with the use of micellar nanodevices based on salophen complexes”, F. Keymeulen, P. De Bernardin, I. Giannicchi, L. Galantini, K. Bartik, and A. Dalla Cort, Org. Biomol. Chem. 2015, 13, 2437–2443).The final part of our study was devoted to the investigation of the applicability of micellar incorporation to other receptors. Two other uranyl-based receptors were studied in cationic CTAX and neutral Triton X-100 micelles. One suffered from chemical stability issues and the other receptor did not perform any better than the ones previously studied. We also studied trimesitylborane which can bind fluoride via Lewis acid-base interactions. This system, which is highly efficient in organic solvents, was shown to be ineffective once incorporated into micelles, probably because the change in the hybridization of the boron atom upon fluoride binding is not favourable in the confined micellar environment. Indolocarbazole-based anion receptors, which recognize acetate and benzoate via hydrogen bonding, were successfully incorporated into DPC micelles, albeit at low concentrations, and were observed to be efficient as the apparent binding affinity measured in water is of the same order of magnitude or higher as the one observed in organic solvents.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished

This thesis describes the preparation, characterization and biological study of block copolymer aggregates as drug delivery vehicles. A novel method is described for the synthesis of biodegradable and biocompatible copolymers of polycaprolactone-b-poly(ethylene oxide). The copolymers and their aggregates are then characterized with special attention given to properties which are of most interest to applications in drug delivery such as copolymer composition, thermal behavior, critical water content, critical micelle concentration, partition coefficient of hydrophobic solubilizates, morphology of the aggregates and in vitro biocompatibility. The polycaprolactone-b-poly(ethylene oxide) copolymer micelles are first explored as a delivery vehicle for the neurotrophic agents FK506 and L-658,818. The in vitro delivery and biological activity of the micelle-incorporated drugs are confirmed in PC12 cell cultures. The in vivo biological distribution of the micelle-incorporated FK506 was assessed in Sprague Dawley rats both 6 and 24 hours following intravenous administration. Also, the biological activity of the micelle-incorporated FK506 was shown to be retained in vivo using the sciatic nerve crush model of peripheral neuropathy in Hanover Wistar rats. The question of whether or not the cellular internalization of the polycaprolactone- b-poly(ethylene oxide) micelles proceeds by an endocytotic mechanism is addressed in PC12 cell cultures. Finally, the polycaprolactone- b-poly(ethylene oxide) micelles are explored as a delivery vehicle for dihydrotestosterone. We report on several of the physico-chemical characteristics of the micelle-incorporated dihydrotestosterone as well as in vitro delivery in HeLa cells which have been cotransfected with the MMTV-LUC reporter gene and the androgen receptor.

Bibliography pages 122-132.
Ten calcium phosphate implant substances (six of natural origin, four of synthetic origin) and several bone samples from a single human skeleton have been qualitatively and semi-quantitatively characterized with respect to several physico-chemical properties. Analysis involved the techniques of X-ray powder diffraction, infra-red spectroscopy, inductively-coupled plasma atomic emission spectroscopy, atomic absorption spectroscopy, and thermal decomposition. In addition, a series of adsorption/exchange experiments were conducted in which implant and bone samples were exposed to progressively increasing concentrations of aqueous Ca²⁺ and Na⁺ ions. X-ray powder diffraction showed that the implants consist of only hydroxyapatite while bones contain small amounts of CaO as well. a-Cell parameters of the implants of natural origin were larger than those of both synthetic implants and bones. The a-cell sizes of the latter two types of samples resembled each other. The c-cell sizes were similar for all samples. The degrees of crystallinity of all implants were higher than those of bone, possibly indicating lower CO₃ contents in the former. %Mass contents of various elements were determined by ICP for implants and bones. Statistical analysis on the bone values showed that variation of elemental concentrations not attributable to experimental error occurred in bone from different regions of the body, but not across the surface of any particular bone. Ratios of Ca/P and Mg/Ca were calculated for all samples, and showed differences between implants and bone due to higher calcium levels in the former. Infrared spectroscopy was used in order to determine %CO₃ values in all the samples. It is suggested that bone contains higher levels of CO₃ than the implants. This was confirmed by analysis of the shapes of certain bands in the spectra of all samples and correlated with XRD results. All samples were subjected to heat up to a maximum of 900°C. XRD scans were recorded after heating to 650°C and 900°C. Percentage mass losses were also recorded at various stages throughout the heating process. Some of the implants revealed traces of tricalcium phosphate (β-TCP) and Cao after heating to 900°C. All bones revealed traces of CaO after heating to 900°C. a-Cell parameters were calculated for all samples and revealed very slight changes in size. Implants exhibited most of these changes after heating to 650°C, while bones did so only after heating to 900°C. Surface chemistry studies further confirmed chemical differences between implants and bone by virtue of the fact that neither exogenous Ca²⁺ nor Na⁺ adsorbed/exchanged with ions in the implants, while bone exhibited a clear saturation curve for each exogenous ion. It is suggested that the techniques and experiments described in this thesis might be utilized by other investigators in the hope of establishing guidelines for the selection of appropriate implant substances.

Cette étude a consisté en la comparaison de turquoises CuAl6(PO4)4(OH)8.4H2O de diverses mines historiques d'Iran (Perse) à celles d'autres localités régionales afin de trouver potentiellement des caractéristiques discriminantes permettant d'identifier la provenance de bijoux ou d’artefacts à turquoise. Des échantillons de mines de turquoise ont été recueillis auprès de trois sources principales : Neyshapour, Damghan et Kerman et de couleur différente. De plus des bijoux à turquoise du Musée des Arts Décoratifs de Paris (MAD) ont également été analysé. Les spectroscopies vibrationnelles Raman et FTIR permettent toutes deux d'identifier la structure de la turquoise. Bien que FTIR ne montre pas de différences particulières entre les différentes couleurs de turquoise, les analyses Raman des échantillons de turquoise bleu et vert montrent que la largeur de ligne de l'échantillon bleu semble beaucoup plus résolue que celle du vert. Cela indique que le réseau et les modes de vibration OH et H2O sont sensibles aux substitutions induisant un désordre cristallin relatif. La spectroscopie d'absorption révèle que les turquoises avec la meilleure couleur bleue présentent une légère absorption de Fe3+. L'influence des ions cuivre divalents et du fer trivalent sur la couleur de la turquoise est expliquée. Selon les résultats d'absorption optique, Fe2+ n'a aucun effet particulier sur la couleur du turquoise ; la substitution Fe3+/Al change la couleur de la turquoise en une couleur verte. De plus, il a été démontré que les cartes élémentaires de spectroscopie de dégradation induite par micro laser (LIBS) permettent d'identifier rapidement les phases turquoise (Cu, Al et P corrélées) ainsi que celles de pyrite (FeS2) et de silicate. De légères interférences entre P, Al et Fe révèlent la légère substitution de Al par Fe.Des analyses chimiques non destructives réalisées par XRF, ont permis de quantifier les éléments majeurs (Al, P, Cu) et les éléments traces (Fe, Zn, As, Ca, Ti). Des analyses de corrélation et par ACP ont été menées en utilisant des données mesurées ainsi que des données bibliographiques. Les bijoux à turquoise du MAD se superposent aux domaines des turquoises de Neyshapour (Fe/Cu vs Zn/Cu; Zn/Cu vs As/Cu; Zn/Cu vs Ca/Cu). Par contre, les turquoises de Kerman ne correspondent pas, ainsi que les turquoises de Chine. Il est donc possible de suggérer que les turquoises des bijoux du MAD antérieures au 19e siècle étaient des turquoises d'origine persane
This study consists in the comparison of turquoise CuAl6 (PO4) 4 (OH) 8.4H2O from various historic mines in Iran (Persia) to those of other regional localities in order to potentially find discriminating characteristics making it possible to identify the origin of turquoise-bearing jewelry or artifacts. Turquoise mine samples were collected from three main sources: Neyshapour, Damghan and Kerman and of different colors. In addition, turquoise jewels from the Musée des Arts Décoratifs de Paris (MAD) were as well analyzed. Both Raman and FTIR vibrational spectroscopy allows to identify the structure of turquoise. Although FTIR does not show any particular differences between the different colors of turquoise, Raman analyzes of the blue and green turquoise samples show that the linewidth of the blue sample seems much more resolved than that of green. This indicates that the network and the modes of vibration OH and H2O are sensitive to the substitutions inducing a relative crystalline disorder. Absorption spectroscopy reveals that even the turquoise with the best blue color has a slight absorption of Fe3 +. The influence of divalent copper ions and trivalent iron on the color of turquoise is explained. According to the optical absorption results, Fe2+ has no particular effect on the color of the turquoise; the substitution Fe3+ / Al changes the color of the turquoise to a green color. In addition, it has been shown that elementary micro laser induced degradation spectroscopy (LIBS) maps allow rapid identification of the turquoise phases (correlated Cu, Al and P) as well as those of pyrite (FeS2) and silicate. Slight interference between P, Al and Fe reveals the slight substitution of Al by Fe. Non-destructive chemical analyzes carried out by XRF, made it possible to quantify the major elements (Al, P, Cu) and the trace elements (Fe, Zn, As, Ca, Ti). Correlation and PCA analyzes were conducted using measured data as well as bibliographic data. MAD turquoise jewelry overlays the turquoise domains of Neyshapour (Fe / Cu vs Zn / Cu; Zn / Cu vs As / Cu; Zn / Cu vs Ca / Cu). The Kerman turquoises do not match, as do the Chinese turquoises. It is therefore possible to suggest that the turquoise stones in MAD jewelry prior to the 19th century were turquoise stones of Persian origin

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 118-126).
Reactive oxygen species (ROS) have emerged as biological signaling molecules, participating in newly discovered cascades that govern cell proliferation, migration, and pathogenesis. A major challenge in understanding these pathways is the lack of detection technologies that allow for spatial and temporal resolution of specific ROS at the cellular level. The goal of this thesis is to design a nanotube sensor platform able to detect and study H2 0 2 signaling fluxes at the cellular level in order to elucidate their role in biological processes. Understanding this role may lead to new therapeutic targets, and improve understanding of biological signaling. Single-walled carbon nanotubes (SWNT) are rolled sheets of graphene and can be either semiconducting or metallic depending on the angle of rolling and the diameter of the tube. Semi-conducting SWNT are one of only a few types of molecules that exhibit band gap photoluminescence (PL) in the near infrared (nIR), making them ideal for detection in biologically relevant media since it avoids biological auto-fluorescence. SWNT are also completely photostable even at high fluence, unlike conventional fluorophores and quantum dot systems, allowing them to serve as nIR single molecule optical sensors capable of long term and stable operations in vitro and in vivo. In this thesis, we show that the 1D quantum confinement of photogenerated excitons in SWNT can amplify the detection of molecular adsorption to where single-molecule discrimination is realizable, even from within living cells and tissues.
(cont.) We have developed a type I collagen film, similar to those used as 3D cell scaffolds for tissue engineering, containing embedded SWNT capable of reporting single-molecule adsorption of quenching molecules such as H₂0₂ . A Hidden Markov Modeling algorithm is utilized to link single-molecule adsorption events detected on the nanotube to forward and reverse kinetic rate constants for many different analytes. The collagen matrix is shown to impart selectivity to H₂0₂ over other ROS and common interferents. We utilized these new single-molecule sensors to study the fluxes of H₂0₂ from A431 human skin carcinoma cells and particularly the local generation rate from Epidermal Growth Factor Receptor (EGFR), a membrane protein and tyrosine kinase that controls cell proliferation among other functions. We show that an array of nIR fluorescent SWNT is capable of recording the discrete, stochastic quenching events that occur as H₂0₂ molecules are emitted from individual A431 and murine 3T3 fibroblasts cells in response to epidermal growth factor (EGF). We also show mathematically that such single molecule detection arrays have the unique property of distinguishing between "near field" and "far field" molecular generation, allowing one to isolate the flux originating from only the membrane protein. Corresponding inhibition experiments suggest a mechanism whereby water oxidizes singlet oxygen at a catalytic site on the receptor itself, generating H₂0₂ in response to receptor binding. An EGFR-mediated H₂0₂ generation pathway that is consistent with all current and previous literature findings has been proposed for the first time and numerically tested for consistency.
(cont.) In an effort to extend this detection to in vivo systems, we investigated how SWNT are uptaken and localized within living cells and as well as their potential cytotoxicity. To this end, we have developed a novel method of studying this problem by tracking the non-photobleaching SWNT in real time by using a single particle tracking method. Over 10,000 individual trajectories of SWNT were tracked as they are incorporated into and expelled from NIH-3T3 cells in real time on a perfusion microscope stage. An analysis of mean square displacement allows the complete construction of the mechanistic steps involved from single duration experiments. We observe the first conclusive evidence of SWNT exocytosis and show that the rate closely matches the endocytosis rate with negligible temporal offset, thus explains why SWNT are non-cytotoxic for various cell types at a concentration up to 5 mg/L, as observed from our live-dead assay experimental results. Further, we studied the cellular uptake and expulsion rates of length-fractionated SWNT from 130 to 660 nm in NIH-3T3 cells using this method. We developed a quantitative model to correlate endocytosis rate with nanoparticle geometry that accurately describes our data set and also literature results for Au nanoparticles. The model asserts that nanoparticles cluster on the cell membrane to form a size sufficient to generate a large enough enthalpic contribution via receptor ligand interations to overcome the elastic energy and entropic barriers associated with vesicle formation.
(cont.) The total uptake of both SWNT and Au nanoparticles is maximal at a common radius of 25 nm when scaled using an effective capture dimension for membrane diffusion. The ability to understand and predict the cellular uptake of nanoparticles quantitatively should find utility in designing nanosystems with controlled toxicity, efficacy and functionality. The development of such single molecule detection technologies for ROS motivates their application to many other unexplored signaling pathways both in vitro and in vivo.
by Hong Jin.
Ph.D.

Doctor of Philosophy
Department of Grain Science and Industry
Sajid Alavi
The feasibility of using a wheat flour mill to refine corn, sorghum and cowpea was studied. Milling of white sorghum grain resulted in decrease in fiber content from 1.89% to 0.38% and 0.45% in raw, finely milled and coarsely milled sorghum respectively. Similarly, there was a reduction in fat (3.17% to 1.75% and 0.51%) content from raw to fine and coarse milled fractions. Starch content increased from 61.85% in raw to 69.80% in fine and 72.30% in coarse fractions. Protein content was almost unchanged at about 7.40% in all the fractions. In de-hulling and milling of cowpeas, starch and protein content increased whereas fiber, fat and ash content decreased. There was a significant difference in expansion characteristics between whole and decorticated binary blends on account of different levels of inherent starch content. Sorghum cowpea (SC) blends had the highest specific mechanical energy (SME) range (285.74 – 361.52 kJ/kg), followed by corn soy (CS) (138.73 – 370.99 kJ/kg) and the least SME was found in sorghum soy (SS) blends (66.56 – 332.93 kJ/kg). SME was found to be positively correlated to starch content in the blends. SC blends had the most stable process followed by SSB and CSB in that order. The milling of expanded extrudates was found to be dependent on bulk density and low bulk density extrudates had bigger particle size and vice-versa. The water absorption index (WAI) for SC was 4.17 g/g to 5.97 g/g, SS ranged from 2.85 g/g to 5.91 g/g and CS ranged from 2.63 g/g to 5.40 g/g. Starch gelatinization ranged from 85.42 – 98.83% for SC, 90.70 – 96.27% for SS, and 72.57 – 95.49% for CS. The starch digestibility increased after extrusion and cooking but there was no significant change in protein digestibility. There was a significant reduction in anti-nutritional factors – phytic acid (26.06 – 44.03%), tannins (18.69 – 26.67%) and trypsin inhibitor (16.55 – 50.85%) after extrusion. Thus, the study showed that high protein blends with superior nutrition density needed for preparation of FBFs could be produced by using existing/traditional milling capabilities and extrusion process.

2006 - 2007
Negli ultimi anni è stato dimostrato che sequenze di DNA (o RNA) ricche in guanine sono in grado di formare una nuova classe di strutture: le quadruple eliche. Importante e' la presenza di quadruple eliche in regioni promotrici e regolatrici di molti geni e nella parte terminale dei cromosomi, i telomeri. Recentemente, lo studio di queste molecole ha avuto un notevole sviluppo grazie alle diverse applicazioni che esse potrebbero avere in campo medico e farmaceutico. In particolare, le quadruple eliche hanno una potenziale applicazione nella terapia anticancro quali inibitori della telomerasi, un enzima la cui iperattività è sicuramente collegata allo sviluppo del cancro. Un promettente approccio per inibire l’attività della telomerasi riguarda l’utilizzo di agenti che possano legare e stabilizzare le quadruple eliche presenti ai telomeri bloccando, in tal modo, l’attività catalitica dalla telomerasi ed agendo da antitumorali. Inoltre, è stato scoperto che oligonucleotidi con struttura a quadrupla elica possono agire da aptameri, cioè hanno la capacità di legare specificamente delle proteine bersaglio, inibendole. L’aptamero denominato TBA (Thrombin Binding Aptamer) è un oligomero a DNA con struttura a quadrupla elica, scoperto in vitro, che è in grado di legare la trombina inibendone la funzione. Il TBA per le sue proprietà anticoagulanti è stato oggetto di numerosi studi sia di tipo strutturale sia di natura farmacologica. L’attività anticoagulante del TBA in vitro è tale da giustificare un suo eventuale impiego in terapia, ma purtroppo tale attività risulta piuttosto bassa in vivo poichè il DNA è rapidamente degradato dalle nucleasi. Uno degli obiettivi di questa tesi di dottorato è stato quello di affrontare uno studio chimico-fisico di composti che sono in grado di legarsi in maniera specifica alle quadruple eliche e dei fattori che regolano gli equilibri in gioco; tali composti sono, infatti, in grado di incrementare la stabilità di questi sistemi e di conseguenza ne possono aumentare l’effetto terapeutico. Per questo motivo è stata studiata la termodinamica dell’interazione di alcune molecole di interesse farmacologico, quali la distamicina, due suoi derivati e la porfirina cationica, con diverse quadruple eliche. Le quadruple eliche prese in esame sono state la d[AG3(TTAG3)3] e la [d(TAGGGTTAGGG)]2 che rappresentano due quadruple eliche formate da un diverso troncamento dal DNA telomerico umano e la d[(TGGGGT)]4 formata da una sequenza troncata del DNA telomerico di Oxytricha e Tetrahymena. Un altro obiettivo è stato quello di caratterizzare la stabilità termodinamica del TBA e di un aptamero modificato (mTBA) ed il processo di binding di questi aptameri con la trombina. L’mTBA presenta una modifica chimica in grado di rendere resistente l’aptamero all’azione delle nucleasi che potrebbe rendere concreto un suo eventuale utilizzo come principio attivo di un farmaco anticoagulante. Inoltre, è stato anche affrontato uno studio computazionale di due quadruple eliche bimolecolari formate da sequenze analoghe di RNA e DNA allo scopo di chiarire i motivi per cui si formano due diverse strutture a quadrupla elica ed i fattori che le stabilizzano. Lo studio è stata condotto principalmente attraverso tecniche calorimetriche quali la calorimetria isoterma (ITC), la microcalorimetria differenziale a scansione (DSC), il dicroismo circolare (CD), e metodi computazionali quali meccanica e dinamica molecolare e docking. I risultati ottenuti per i sistemi quadrupla elica-ligando dimostrano che la distamicina ed un suo derivato contenente un anello metil pirrolico in più ed un gruppo ammidico terminale, legano le quadruple eliche in esame, al contrario un secondo derivato della distamicina contenente due anelli metil pirrolici in più ed un gruppo ammidico terminale non ha mostrato avere interazioni specifiche. I parametri termodinamici ottenuti indicano che le interazioni quadrupla elica-ligando sono fortemente influenzate dallo ione presente in soluzione e che anche la stechiometria di legame è dipendente dal tipo di soluzione. Il calcolo dei parametri termodinamici ha mostrato che, sia in sodio che in potassio, il legame della distamicina e del composto I alle quadruple eliche in esame è entropicamente guidato. Questo dato in particolare suggerisce che il binding di queste molecole potrebbe avvenire nei solchi delle quadruple eliche. Inoltre, un risultato particolarmente interessante è che il composto I ha mostrato, in entrambe le soluzioni, una maggiore affinità della distamicina per le quadruple eliche. I risultati ottenuti per l’interazione porfirina-[d(TAGGGTTAGGG)]2 sono in generale accordo con la struttura cristallografica, recentemente riportata, del complesso ed indicano un binding entalpicamente guidato con una stechiometria 2:1. Lo studio della stabilità termodinamica del TBA e del TBA modificato ha rivelato che l’introduzione della modifica aumenta sia la stabilità termica che termodinamica dell’aptamero. Inoltre, i valori delle variazioni di entalpia ed entropia per la dissociazione del TBA modificato risultano più elevati rispetto al TBA, suggerendo una struttura più rigida e la presenza di ulteriori interazioni intramolecolari nell’aptamero modificato. Questi risultati sono stati confermati ed interpretati sulla base dei risultati delle dinamiche molecolari dei due aptameri. I parametri termodinamici del processo di binding del TBA e del TBA modificato con la trombina mostrano che l’interazione è esotermica e che la stechiometria del complesso che si forma è 1:2 (aptamero:proteina). Il TBA modificato risulta però avere una più alta affinità per la trombina e la sua interazione è associata ad una variazione di entalpia maggiormente favorevole. I risultati delle dinamiche molecolari dei complessi suggeriscono che la maggior affinità dell’aptamero modificato sia dovuta essenzialmente ad una migliore interazione con l’esosito II della trombina. Lo studio di dinamica molecolare delle quadruple eliche di RNA e DNA ha evidenziato che la maggiore differenza tra le due molecole deriva dalla presenza del gruppo 2’-OH del ribosio, che contribuisce considerevolmente al numero di legami idrogeno formando più interazioni intramolecolari nella molecola di RNA. I legami che hanno una maggiore persistenza sono quelli formati con l’ossigeno del gruppo fosfato. Questo tipo di legame idrogeno conferisce rigidità alla struttura ed è in parte responsabile della stabilità delle esadi presenti nella quadrupla elica di RNA. Inoltre, durante le simulazioni, gli ioni Na+, inizialmente non direttamente coordinati alle quadruple eliche, vanno a coordinare in modo stabile le macromolecole indicando un possibile meccanismo di coordinazione non ancora osservato sperimentalmente. Parte della ricerca è stata svolta in collaborazione con la Prof. Concetta Giancola del Dipartimento di Chimica dell’Università Federico II di Napoli. Inoltre, una parte dello studio è stato realizzato a Londra presso i laboratori del Prof. Stephen Neidle della School of Pharmacy dell’University of London, e presso il gruppo della Dott. Franca Fraternali, della Randall Division del King’s College London. [a cura dell'autore]
VI n.s.

The development of selective and sensitive sensors for anionic species in water is a growing field of research. In particular, the detection of fluoride in aqueous samples is of great interest because of health related problems attributed to this anion. Furthermore its small size and its high hydration energy make it a particularly

challenging species to recognize in water.

Uranyl-salophen receptors have shown to be good receptors for this anion in organic solvents due to their hard Lewis acid character which makes them good binders for the hard Lewis base fluoride. However they are not water soluble.

The incorporation of uranyl-salophen receptors 1-3 within cationic micelles (CTABr and CTACl) will make them “water-compatible” and give us the possibility to study the behaviour of these system in water. The 3 receptors shown

in figure 1 were studied in this thesis. Preliminary work had already been reported on receptor 1 in CTABr micelles. Binding affinities studies showed that these receptors have binding constants for fluoride of the order of 104 M−1 which is two orders of magnitude higher than

the value obtained for the same receptors in a less competitive solvent such as methanol. This suggests that the micellar environment has an effect, not only on the solubility of the receptors in water, but also for the binding process.

Physico-chemical studies were undertaken on the system in order to obtain some structural informations. Dynamic Light Scattering experiments showed an increase in the size of the CTABr micelles upon receptor’s incorporation but not on the CTACl ones.

NMR studies, including chemical shift variation measurements, nOe and Paramagnetic Relaxation Enhancement (PRE) experiments, were undertaken in order to analyse the location and orientation of the receptors in the micelles. Results indicate that receptor 1 is located at the micellar surface, in CTABr micelles and a little deeper in CTACl micelles, orienting the receptors binding site towards the exterior of the micelle. Receptor 2 is more buried inside the micelles compared to receptor 1 but with a similar orientation. Receptor 3 is the most deeply buried

in the micelles, and the experiments suggests that no preferential orientation is adopted.

A systematic study of the factors affecting PRE measurements was also undertaken showing the dependency of this measurements on the surfactant concentration, the nature of the counterion and the ionic force. A method, based on the normalization of the relaxivity values to the value obtained for the micelle polar head is proposed in order to avoid all the variations due to the experimental conditions and thus enabling the comparison of different systems.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Thesis submitted for the Degree in Master of Energy and Bioenergy
A presente dissertação tem como objectivo principal o estudo da valorização dos carvões obtidos na co-pirólise de resíduos de plásticos, pneus e biomassa florestal. Os carvões pirolíticos foram submetidos a um tratamento multietápico tendo em vista a obtenção de materiais carbonosos de valor acrescentado. Realizou-se uma caracterização físico-química dos carvões tratados tendo em vista o estudo de possíveis aplicações destes materiais, nomeadamente, a possibilidade de serem utilizados como adsorventes de poluentes. Os carvões pirolíticos brutos foram submetidos a uma extracção sequencial com solventes orgânicos de polaridade crescente seguida de uma desmineralização ácida. Os resultados obtidos demonstraram que o procedimento multietápico realizado garantiu uma descontaminação eficiente dos carvões, permitindo a recuperação de uma fracção significativa dos óleos da pirólise e/ou de subprodutos condensados que ficaram retidos nos carvões brutos, assim como uma redução significativa do seu conteúdo em cinzas. O procedimento de desmineralização ácida realizado permitiu também concluir que os metais pesados maioritários, assim como os mais tóxicos, estão significativamente imobilizados e retidos na matriz dos carvões, desde que não sejam aplicadas condições acídicas agressivas. A análise elementar aos carvões permitiu determinar heteroátomos como o oxigénio, enxofre e azoto, sendo este facto indicativo da presença de grupos funcionais na superfície dos carvões, o que representa um interesse acrescido relativamente à adsorção de poluentes orgânicos e inorgânicos específicos. As propriedades texturais e de adsorção dos carvões tratados foram determinadas e os resultados obtidos indicaram que estes carvões são predominantemente materiais meso e macroporosos, com capacidade para adsorver moléculas volumosas. O tratamento aplicado aos carvões permitiu obter materiais carbonáceos com qualidade suficiente para serem reutilizados como adsorventes ou como percursores de carvão activado.

Synthetic molecular receptors find applications in the selective extraction, transport and detection of neutral or charged species and the study of these systems is an important facet of supramolecular chemistry. In this thesis, we focused our attention on a specific family of molecular receptors called calix[6]arenes. These receptors possess a hydrophobic cavity formed by 6 aromatic rings that can accommodate small organic molecules. They can furthermore be easily functionalized and give rise to for example ditopic receptors or sensing systems. We worked with two families of calix[6]arenes but also looked at the complexation properties of some related compounds: a homooxacalix[3]arene and a resorcin[4]arene derivatives. The first part of this thesis is devoted to the study of the complexation properties of a fluorescent calix[6]tris-pyrenylurea. The binding of anions, ion pairs, ion triads and phospholipids was monitored by 1H Nuclear Magnetic Resonance (NMR) and Emission Spectroscopy. Our results showed that the receptor exhibits a remarkable selectivity for the sulfate anion in DMSO for which a binding constant of the order of 103 M-1 was found. In chloroform the affinity for sulfate is of the order of 105 M-1 and the selective recognition of ammonium-TBASO4 triads was observed (TBA = tetra-n-butylammonium; ammonium = PrNH3+, HexNH3+ or DodNH3+). This work has been reported in the paper “Fluorescent Chemosensors for Anions and Contact Ion Pairs with a Cavity-Based Selectivity” Emilio Brunetti, Jean-François Picron, Karolina Flidrova, Gilles Bruylants, Kristin Bartik and Ivan Jabin J. Org. Chem. 2014, 79, 6179–6188. We also showed that calix[6]tris-pyrenylurea displays a remarkable selectivity in chloroform for phospholipids bearing a phosphatidylcholine head (PCs) over those bearing a phosphoethanolamine head (PEs). We were able to show that this fluorescent receptor is able to extract PCs from a water solution enabling their quantification. This work has been reported in the paper “A Selective Calix[6]arene-based Fluorescent Chemosensor for Phosphatidylcholine Type Lipids” Emilio Brunetti, Steven Moerkerke, Johan Wouters, Kristin Bartik and Ivan Jabin Org. Biomol. Chem. 2016. Accepted Manuscript. DOI: 10.1039/C6OB01880G.The second part of this thesis is devoted to the evaluation of the binding properties of different receptors incorporated into dodecylphosphocholine (DPC) micelles. This strategy was used to make the hydrophobic molecular receptors “water-compatible” without having to undertake synthetic modifications. Our results showed that a calix[6]azacryptand-based receptor can be incorporated into DPC micelles, either as a zinc complex or as a polyammonium at low pH. We observed that the zinc complex incorporated in the micelles is able to bind small and long linear primary amines in its cavity and we were able to highlight that complexation is driven by the hydrophobic effect. This work has been reported in the paper “Primary Amine Recognition in Water by a Calix[6]aza-cryptand Incorporated in Dodecylphosphocholine Micelles” Emilio Brunetti, Alex Inthasot, Flore Keymeulen, Olivia Reinaud, Ivan Jabin and Kristin Bartik Org. Biomol. Chem. 2015, 13, 2931-2938.We also validated the micellar incorporation strategy with a homooxacalix[3]tris-acid and with a resorcin[4]arene zinc complex bearing four methyl-imidazole moieties. Once incorporated into DPC micelles, we showed that the two receptors can bind small organic guests: the homooxacalix[3]arene derivative can bind tert-butylammonium or adamantylammonium, albeit with low affinity and the resorcin[4]arene-based zinc complex can bind acetate and acetylacetone.The final part of this thesis is devoted to the work undertaken in order to try and elucidate the guest exchange mechanism of calix[6]arene-zinc complexes where the zinc is tri-coordinated to the calixarene-based ligand and coordinates a guest molecule inside the calixarene cavity. The hypothesis that we put forward is that when the zinc is only tri-coordinated to the calixarene ligand, the guest exchange mechanism involves a zinc penta-coordinated intermediate where the zinc atom is simultaneous coordinated to an endo-complexed guest (inside the cavity) and an exo-complexed molecule (outside the cavity). 1D EXchange SpectroscopY experiments (EXSY) were undertaken with two calix[6]arene-zinc complexes where the zinc is tri-coordinated to the calixarene ligand and with a calix[6]arene-zinc complex where the zinc is tetra-coordinated to the calixarene ligand. The exchange of different guests (ethanol, dimethylformamide and acetonitrile) was monitored in deuterated dichloromethane. We observed that in all cases water accelerates guest exchange but that the guest residence times are highly dependent on the acidity of the metal center and on the nature of the guest buried inside the cavity.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished

Present PhD thesis aimed to investigate relatively unknown properties of halloysite nanoparticles, as well as to further examine HNTs as potential drug nanocarriers. NPs loading and release characteristics were studied using model active molecules: magnesium monoperoxyphthalate (MMPP), aspirin and epirubicin. The research was fulfilled with formation of complex multi-functional nanoarchitectures, which apart from ability to deliver incorporated drugs, showed the potential of controlled and sustain release of therapeutics, biocompatible and bioresorbable characteristics as well as potential targeting abilities. Great attention was dedicated to characterization of formed halloysite-based nanoarchitectures in qualitative as well as quantitative manner. Investigations performed in this thesis also faced the problem of exceeding dimensions of halloysite units, nanoparticles aggregation, poor loading capability and dose dumping effect. Subsequently, studies for trying to find a solution to these obstacles were undertaken. Fully characterized halloysite nanoconstructs were further examined in biological field, employing different cancer cell lines. Studies on pristine halloysite nanotubes: Physico-chemical and biological properties of halloysite nanoparticles were evaluated using microscopic techniques, spectroscopic analysis, surface studies regarding charge, porosity and wettability. The thermal and time-based examination of pristine halloysite was performed as well, showing stability of HNTs alumino-silicate skeletons up to ~400 ℃ and over a long period of time (2 years) at room temperature, however with a variable amount of incorporated water molecules. Biological performance of HNTs was determined in vitro in multiple cellular systems by toxicity, cellular uptake, colocalization and accumulation studies using [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] tetrazolium reduction (MTT) assay and set of microscopic techniques. Aiming to deeply characterize halloysite nanoparticles, the study proceeded with employment of non-standard techniques, as multiphoton microscopy that drove to discovery of novel NPs promising capabilities. It was revealed that halloysite is able to convert light to its second harmonic, at twice of the frequency (and therefore half of the wavelength) while using high intensity femtosecond pulsed laser. Halloysite Second Harmonic Generation (SHG) signal was detected over a broad wavelength range, showed stability over a long period of time, polarization properties and quadratic dependence on the intensity of incident light. The analysis also pointed out characteristic structure properties of the nanoparticle that is lack of the center of symmetry and the high crystalline structure organization. Among a wide spectrum of domains where discovered HNTs characteristics can be utilized (e.g. optoelectronics, biosensors), we have explored its application in alternative label-free bioimaging. The proposed multiphoton method of analysis showed advantages over the standard confocal microscopy, since e.g. nanoparticles did not have to be stained prior the analysis, thus no possible alterations of HNTs including size, surface chemistry and consequent cellular uptake were induced. Therefore, for the first time, halloysite nanotubes were exploited as imaging agents, taking advantage of their endogenous properties. Along the research it was revealed that the length of pristine HNTs and the strong aggregation limit their ability to pass intracellular membranes and thus minimize their effectiveness as drug nanocarriers. Therefore, efforts were devoted to the development of facile methodology to efficiently disperse and shorten HNTs units. Set of characterizations techniques, such as Scanning Electron Microscopy (SEM) analysis with size distribution profile and nitrogen adsorption Brunauer–Emmett–Teller (BET) method revealed that the applied ultrasonication procedure resulted with longest tubes breaking and favored obtaining HNTs below 300 nm in length (39.1 % to 76 % of the batch). The number of voids among the pristine nanoparticles when packing together (123–43 nm) greatly increased (total pore volume from 0.23 cm^3/g to 0.30 cm^3/g), meaning that the nanomaterial was efficiently disaggregated as well. In vitro internalization and colocalization studies by Scanning Electron and Multiphoton Microscopy demonstrated that the sonicated halloysite were preferentially internalized via macropinocytosis within 60 min and accumulated in the perinuclear region within 24 h. Halloysite application in nanomedicine: To study halloysite potential as a carrier for drugs, we set up the preparation and characterization of hybrid nanoconstructs with model molecules such as magnesium monoperoxyphthalate hexahydrate (MMPP), a negatively charged oxidizing agent, aspirin, an anti-inflammatory drug and epirubicin, a chemotherapeutic. Chosen molecules were incorporated with 3.5 %wt, 1.1 %wt and 5.1 %wt capacity, respectively for MMPP, aspirin and epirubicin. Loading efficiency (LE) improvement was achieved through the choice of the right solvent (1), enhancement of electrostatic forces between nanoparticle and the drug, via functionalization of HNT surfaces with an active linker (2), as well as NPs structure modification leading to increase of inner lumen volume (3). Specifically, the use of water: EtOH (7:3 v/v) as a solvent instead of water, increased MMPP loading capacity up to 6.1 %wt. Poor incorporation of aspirin was improved by enhancing electrostatic forces between deprotonated aspirin molecules and modified HNTs inner walls with amine-rich organosilane. It was also demonstrated that by enlarging volume of the NPs cavities, more molecules could be loaded. To do that, pristine HNTs were treated with 0.1M aqueous solution of NaOH, which resulted in an exfoliation of bilayers located inside the lumen. At the same time, outer surface of the halloysite tubules was preserved. As a consequence of the base treatment, halloysite cylinders gained more volume in the inner cavity as concluded from Transmission Electron Microscopy (TEM) and nitrogen adsorption BET analysis. The actual test on loading capacity using model MMPP molecule revealed increased MMPP incorporation from 6.1 % wt to 11.7 %wt. To evaluate if the activity of MMPP as an oxidizing agent remained unchanged upon incorporation and release from halloysite, and therefore to demonstrate the inactivity of the inorganic skeleton towards carried molecule, we tested HNT-MMPP nanoconstruct with selective fluorescent 1,3-diphenylisobenzofuran (DPBF) probe. Among available modifications of halloysite nanoparticles via covalent bond, the surface silanization is commonly recognized as one of the most efficient and widespread reaction while HNT manipulation. Up to date, the halloysite nanotubes functionalized with silanes have been used as a support for versatile applications in diverse scientific domains, including enzymes immobilization and biosensing. Willing to explore the halloysite functionalization with those active linkers, we have performed grafting reactions with representative organosilanes carrying the same backbone, while varying in the content of terminal groups, namely (3-aminopropyl)triethoxysilane (APTES), 3-(2-aminoethylamino)propyldimethoxymethylsilane (AEAPS), (3-mercaptopropyl)trimethoxysilane (MPS). Successful HNTs surfaces functionalization with organosilanes was demonstrated by means of quantitative thermogravimetric analysis (TGA) that allowed to estimate the loading capacity of organosilanes to be of 5.7 %wt for APTES, 7.4 %wt for AEAPS and 0.7 %wt for MPS. In addition, particular attention was dedicated to further quantify incorporated organosilane (APTES), since only one method has been so far reported, that is the destructive thermogravimetric analysis (TGA). For this reason, we set up and optimized a Fmoc based method by performing the following three reactions: (i) synthesis of “APTES-Fmoc” molecule; (ii) halloysite functionalization with “APTES-Fmoc”; and (iii) time-dependent Fmoc deprotection reaction in piperidine: EtOH (20 %) solution, resulting in dibenzofulvenepiperidine adduct (DBF-pip) formation. The UV-visible spectroscopic analysis of supernatant solutions demonstrated that the DBF-pip deprotection from halloysite support needs 5 h to be completed. Therefore, it was evidenced that HNT Fmoc-method showed strong coherence with already existing TGA method (± 2 % measurement error) and stood out as a valuable complementary technique for quantification of silane grafting on HNTs surface with additional low-cost and nondestructive advantages. The possibility of using halloysite nanotubes as a non-viral gene delivery nanosystem for therapeutic treatments was studied as well. Aiming to immobilize plasmid DNA (pDNA) based on the Green Fluorescent Protein (GFP) on HNTs support, the layer-by-layer (LbL) adsorption technique was applied. Obtained multi-component assembly was characterized qualitatively by monitoring variation in nanoparticle physico-chemical properties including surface charge, mass weight, presence of functional groups at each step of hybrid formation, which confirmed the successful nanoarchitecture formation. In order to additionally demonstrate the presence of GFP encoding plasmid (pGFP) on HNTs, the nanoarchitecture was treated with the bovine pancreatic deoxyribonuclease (DNase) enzyme, which induced the pGFP degradation through hydrolytic cleavage of phosphodiester linkages in DNA backbone. Thus, as expected, such nanoform with deposed genetic material varied in physico-chemical properties, expressing similar ones of the nanoconstruct without pGFP plasmid attached. The biological efficiency of HNTs-pGFP nanosystem was checked by means of Multiphoton microscopy. Successful pGFP plasmid transportation into cells was verified by detection of GFP expression, which yielded fluorescence emission. The interesting and innovative aspect of this case study was the simultaneous observation of GFP expression via fluorescence detection, and colocalization of halloysite nanoparticles by their SHG signal. This study proved that halloysite can act as an efficient carrier of genetic material, since free pGFP cannot be internalized by same cells, due to its large size and significant charge. Drug-loaded halloysite nanoconstructs (HNT-MMPP, HNT-APTES-aspirin) were also examined on the drug release kinetics, demonstrating long-term MMPP leakage taking 18 days and aspirin over 60 min. However, great drug liberation into the solvent of release was observed in the first minutes, followed by desired sustained drug release. The initial molecule liberation (dose dumping effect) is known to entail local toxicity. Herein, trying to find a solution to this problem, the coating of HNTs with the natural collagen polymer was investigated. Two strategies for the loading with this biopolymer were studied: (i) formation of a covalent bond between collagen and APTES-modified HNTs using glutaraldehyde cross-linker or (ii) noncovalent adsorption of collagen into pores of NPs. Immobilization of collagen on the surface of HNTs was estimated to be 3.7 %wt (i) and 1.8 %wt (ii). Other supplementary characterization techniques, such as water contact angle, ζ–potential analysis, Kaiser test, ultraviolet and visible (UV-vis) spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) were in accordance and proved nanoarchitectures formation. For the visualization purpose of HNTs encapsulated in collagen shell, the innovative characterization technique was implemented, namely 3D Multiphoton microscopy. It revealed that the biopolymer coating blocked the entrances of the hollow tubes thus, entrapping the drug in NPs. Mimicking tumor microenvironment (TME), the pH and/or enzyme triggered release was performed. LC-Mass analysis revealed that the collagen coating slowed down the release of aspirin from HNTs. Studies on cells showed that the collagen coating on HNTs is biocompatible and cell viability assay performed on 5637 urinary bladder and HeLa cervical cancer cell lines demonstrated the sustained release of the entrapped epirubicin chemotherapeutic agent in the biological context. Industrial application of halloysite: During a stage in BASF SE (USA), validation and properties enhancement of halloysite-based products potentially manufacturable in the company on an industrial scale were studied. In particular, the research was dedicated to aspects such as the pH-dependent dispersion behavior of halloysite nanotubes and iron coarse impurities removal from bulk samples. Applied methodologies and set of physico-chemical characterization techniques generated and revealed decreased percentage of present aggregates, maintained low shear viscosity under the threshold value and increased solids loading capacity in final halloysite-based products. Conclusions: In conclusion, PhD studies here reported contributed to the exploration of halloysite nanotubes for their application in the nanomedical and industrial fields. The investigations suggest a facile manipulation and functionalization of HNTs, useful for properties modification and improved NPs performance. Specifically, the study was directed toward formation of multi-functional nanocarriers with controlled drug delivery and release properties, together with targeting and imaging abilities. Moreover, the research was completed with halloysite-related technology transfer to the BASF SE, for the purpose of knowledge increase in the halloysite-field and bringing forward placement of halloysite-based products on the market. The systematic study on HNTs characterization and application performed in this PhD thesis will contribute to the development of HNTs as a high performance structural and functional material.

Thesis (M.Sc. (Soil Science)) --University of Limpopo, 2013
The study was conducted to assess the impact of mining activities on selected soil physical, chemical and microbial properties on farmlands around three selected mining sites. Nine soil samples were collected from each of the following farms : Hans Merensky, Mogoboya and Leon Tom, Foskor Mine and JCI mining sites, respectively. Additional nine soil samples were collected from non-polluted Waterbok farm that serves as a control for the purpose of comparison. The samples were taken at 0–15, 15–30, 30–45 cm depths at three sampling points on each farm for physical, chemical and biological studies. However, soil samples collected for microbial (fungi, bacteria and actinomycetes) counts were surface (0–15 cm) soil samples. Soil chemical properties determined include pHw, electrical conductivity (ECe), exchangeable acidity (EA), organic carbon, available phosphorous, exchangeable cations as well as heavy metal (i.e. Mn, Zn, Cu, Pb, Cd, As and Sb) concentrations. The physical parameters determined include texture (sand, silt and clay) as well as bulk density. Soil pHw and ECe values decreased with depth; and ranged from 6.94 to 6.50 and from 12.24 to 10.76 mS cm-1, respectively. Exchangeable acidity showed a gradual increase with depth and ranged from 0.72 to 0.80 cmol(+)(kg), while percent organic carbon decreased with depth ranging from 1.41 to 2.19 %. Exchangeable cations, particularly K and Mg increased with depth while Ca decreased marginally with soil depth. Available phosphorous content decreased following increases in distance from the pollution source while heavy met.al contamination decreased with soil depth but increased further away from the pollution source. Significantly high loads of Pb, As and Sb were recorded at all depths on the three farms around the mining sites, which were largely responsible for the pollution but worse on the Leon Tom farm; with Pb constituting the greatest pollutant. The concentration of extractable heavy metals in the studied areas was in the order: As >Sb>Pb>Zn>Cu >Mn >Cd. Cadmium level appeared generally very low in all samples while elevated levels of Mn, Cu and Zn were detected at all depths in the polluted soils.Significant differences in microbial levels were detected at the various sampling points. The highest count of 3.82 and 6.20 CFU g-1 for fungi and actinomycete, respectively were both from the Leon Tom farm, while 6.46 CFU g-1 counts for bacteria was obtained from Mogoboya farm. Interestingly, fungal and actinomycetes activities were more sensitive to heavy metal contamination than bacteria that were significantly increased following soil pollution.
National Research Foundation (NRF)

Thesis (MSc. (Soil Science)) -- University of Limpopo, 2015
There exists a considerable level of spatial variability in soil physical and chemical properties within the research block; and the soils are generally shallow. Of all the measured parameters, electrical conductivity, Bray-1 P, exchangeable potassium, calcium and sodium as well as extractable iron and zinc showed a huge percent of variation across the field. Soil variability maps indicated the degree of variability within the research block. The spatial variability of the characterized parameters was significant across the research block. A correlation study was conducted to investigate the relationship between the measured soil physical and chemical properties. Regular soil analyses should be conducted to avoid failure/delay of experiments. It is recommended that inputs such as irrigation and fertilizer application must be varied based on varying soil conditions across the research block.
VLIR project 6 leaders

La technique du sfumato, de Léonard de Vinci, permet, par un jeu subtil des ombres et des lumières, de créer un effet vaporeux ‘sans lignes, ni contours, à la façon de la fumée'. Léonard de Vinci, pour la réalisation des ombres des carnations, superpose des glacis, fines couches de peintures translucides, composés d'un pigment sombre et très riches en liant organique. Les livres de recettes et traités de peinture anciens constituent une première source d'informations sur cette technique. La reconstitution de certaines recettes de liants suivie par la caractérisation de leurs propriétés rhéologiques et mécaniques a permis de mieux comprendre la formulation des glacis. Les critères définis par l'industrie des peintures peuvent être utilisés comme autant d'indices pour retrouver les recettes des peintres des siècles passées. L'analyse de prélèvements peut apporter certaines informations sur la formulation des couches picturales chez Leonard de Vinci et ses contemporains. La combinaison de deux méthodes d'analyse par faisceau d'ions (PIXE et BS) permet d'obtenir la proportion liant-pigment d'une couche de peinture, information jusqu'alors non accessible. Enfin, des œuvres de Léonard de Vinci ont été analysées de façon quantitative par spectrométrie de fluorescence des rayons X. En considérant l'atténuation des rayons X par absorption, il est possible de calculer la composition et l'épaisseur des couches à partir d'une modélisation de la stratigraphie de l'œuvre.

La découverte de protéines fluorescentes photo-transformables (PTFP) au cours des dernières décennies a révolutionné le domaine de la microscopie optique. Les protéines fluorescentes réversiblement commutables (RSFP), en particulier, sont couramment utilisées pour les techniques de microscopie à super-résolution comme en RESOLFT (REversible Saturable OpticaL Fluorescence Transitions) par exemple. Par photoactivation, les RSFP passent d'un état "on" - fluorescent - à un état "off" - éteint - qui, combiné à des systèmes d'illumination avancés permet d'imager des composants cellulaires préalablement marqués à une résolution nanométrique. De nombreuses études cristallographiques sur les RSFP ont apporté des informations structurelles importantes et ont permis de dresser des hypothèses quant à leur comportement photo-physique. Elles ont également guidé l'ingénierie des protéines fluorescentes afin d'améliorer leur conception et leur utilisation in vivo. Cependant, les cristaux de ces protéines qui sont étudiées à des températures cryogéniques ne permettent pas de capturer la dynamique moléculaire des RSFP dans le but de comprendre, voir d'améliorer leur propriétés photo-physique. C'est pourquoi au cours de ma thèse, j'ai majoritairement utilisé la résonance magnétique nucléaire (RMN) en solution multidimensionnelle sur une RSFP verte - appelée rsFolder - afin de compléter et améliorer nos connaissances sur ces protéines. À l'aide d'un dispositif d'éclairage laser in situ portatif couplé au spectromètre RMN, j'ai pu extraire des informations dynamiques locales quantitatives concernant les états "on" et "off" fluorescents de rsFolder qui sont respectivement caractérisés par un chromophore en conformation cis et trans. Les signatures des résidus dans l'état "off" non fluorescent ont été identifiées à l'aide d'expériences de RMN d'échange induite par LASER. L'état "off" métastable de rsFolder apparaît plus dynamique dans l'échelle de temps de la milliseconde que l'état "on" fluorescent. La RMN a également permis de mettre en lumière quatre configurations du chromophore possible qui sont pH dépendante. De plus, j'ai observé pour la première fois l'isomérisation du chromophore induite par le pH cis-trans. Les valeurs dérivées de la RMN des énergies d'activation concernant l'isomérisation et les différences d'énergie libre entre le chromophore cis et trans ont permis de cartographier le paysage d'énergie libre de l'état fondamental de rsFolder à différents pH. Enfin, la comparaison de données de RMN et des mesures optiques sur rsFolder ainsi que sur différents mutants a mis en évidence le rôle important que la RMN peut jouer dans le domaine de l'ingénierie des RSFPs.Dans l'ensemble, mes travaux de thèse ont permis non seulement d'établir un système d'illumination in situ fiable, accompagné d'expériences de RMN pertinentes dans le but d'étudier les RSFP mais aussi de souligner l'importance de la dynamique moléculaire dans la compréhension des propriétés photo-physiques des RSFPs
The discovery of Phototransformable Fluorescent proteins (PTFPs) over the last decades has revolutionized the field of microscopy. Reversibly photo-switchable fluorescent proteins (RSFPs), in particular, are currently routinely used for Super Resolution Microscopy techniques, such as RESOLFT (REversible Saturable OpticaL Fluorescence Transitions). Photo-induced switching between a fluorescent "on"- and a dark "off"-state, in combination with advanced illumination schemes has allowed for imaging nanometer sized compartments in biological cells. Crystallographic studies of such RSFPs have provided useful mechanistic explanations for their photophysical behaviour and has guided fluorescent protein engineering into designing better tags. However, the crystal forms of such proteins studied at cryogenic temperatures fail to capture dynamics present in RSFPs which could potentially play a significant role in their photophysics. So far, only a single NMR study for the RSFP Dronpa has been reported in the literature (Mizuno, 2008). During my PhD thesis, I was able to complement crystallographic studies of rsFolder, a green RSFP, with a dynamic perspective using multidimensional solution NMR spectroscopy.Using a portable in-situ laser illumination device coupled with the NMR spectrometer, I was able to extract quantitative local dynamic information for both the fluorescent "on"- and "off"-states of rsFolder, characterized by a primarily cis and trans chromophore, respectively. NMR signatures of residues in the non-fluorescent "off"-state were identified using LASER-driven Exchange NMR experiments. The metastable photo-induced "off"-state of rsFolder appears more dynamic on the millisecond timescale than the fluorescent "on"-state. NMR investigations of the chromophore resulted in the deciphering of four configurations, populated in a pH-dependent fashion. Moreover, pH-induced cis-trans isomerization of the chromophore was observed, in the absence of light. NMR-derived values of activation energies for isomerization and free energy differences between the cis and trans chromophore enabled the mapping of the ground-state free energy landscape of rsFolder at different pH values and buffer compositions. Lastly, comparing NMR observables with optical measurements on rsFolder and mutants highlights the potential role that NMR can play in the field of RSFP engineering. Altogether, my PhD work yielded in not only a reliable in-situ illumination set-up accompanied with relevant NMR experiments to study RSFPs, but also highlighted the importance of dynamics in understanding RSFPs' photophysical properties

Dans ce travail, nous nous concentrons sur la caractérisation de l'environnement physico-chimique des éléments présents dans des multicouches à base de cobalt qui travaillent dans les domaines des rayons X mous et extrême ultra-violet (EUV). L'observation des modifications des interface des deux systèmes Co/Mo2C et Co/Mo2C/Y lors du recuit est important pour l'amélioration de leurs performance optique. Ils ont été étudiés en combinant des méthodes non destructives, spectroscopie d'émission des rayons X, résonance magnétique nucléaire, réflectométrie de rayons X et des méthodes destructrices, spectrrométrie de masse d'ions secondaires par temps de vol et la Microscopie électronique en transmission pour étudier leurs propriétés interfaciales. Ce travail vise non seulement à la conception et la fabrication de nouveaux éléments optiques pour faire face au développement des sources et des applications dans les demaines des rayons X mous et l'EUV, mais aussi à développer une méthodologie combinant des simulations et des expérimentations consacrée à l'analyse des interfaces dans structures multicouches afin d'améliorer leur propriétés optiques
In this work, we focus on the characterization of physico-chemical environment of the element present in Co-based multilayers working in the soft x-ray and EUV ranges. The observation of interface changes of both systems Co/Mo2C and Co/Mo2C/Y upon annealing is important for improving their optical performance. They were studied by combining non-destructive methods, x-ray emission spectroscopy, nuclear magnetic resonance spectroscopy, x-ray reflectometry and destructive methods, time-of-flight secondary ions mass spectroscopy and transmission electron microscopy to investigate their interface properties. This work aims not only at designing and fabricating new optical elements to face the development of sources and applications in the EUV and soft x-ray ranges, but also at developing a methodology combining simulations and experiments devoted to the interface analysis in these multilayer structures in order to improve their optical properties