La contamination de l'environnement aquatique par les éléments traces métalliques (ETM) est un des problèmes majeurs auxquels est confrontée la société actuelle. Ces métaux transitent dans la colonne d'eau avant de s'accumuler dans les sédiments où ils sont impliqués dans de nombreuses réactions biogéochimiques susceptibles de modifier plus ou moins fortement leur spéciation et donc leur (bio)disponibilité pour l'ensemble du réseau trophique. C'est au sein de ces problématiques centrées sur le devenir des ETM dans l'environnement aquatique que s'oriente ce travail de recherche. Inscrites dans le programme européen INTERREG-III Stardust, nos recherches ont été menées principalement dans trois sites d'études transfrontaliers franco-belge: l'Escaut, la Lys et !'Espierre. La distribution des ETM dans les sédiments des 3 sites a mis en évidence une forte contamination par le cadmium. Cependant, ces sédiments sont caractèrisés par un bon piégeage des ETM par les sulfures (principalement Cd, Cu, Pb et Zn) et dans une moindre mesure Ni et Co, plus labiles. Différents indices de qualité des sédiments et des eaux interstitielles ont ici été utilisés et ont montré que les sédiments de l'Espierre paraissaient peu toxiques en raison des fortes teneurs en AVS alors que les eaux interstitielles l'étaient davantage à cause d'une dureté relativement faible. D'autre part, la mise au point de DGT-AgI pour la mesure des sulfures a été mise en application et a permis de mettre en évidence l'effet saisonnier sur la production de sulfures dans les sédiments de la Mer du Nord. Parallèlement à ces recherches, le développement de microélectrodes d'or a finalement permis de suivre en continu dans la colonne d'eau, la concentration en Zn et Pb à des concentrations de l'ordre du ppb et des essais ont été réalisés directement dans le sédiment. / The pollution of aquatic ecosystems by trace metals (TM) is one of the major problems to which is faced our present society. These metals pass in transit through the water column and are finally trapped in sediments. From then on, they are involved in several biogeochemical reactions that likely modify more or less significantly their speciation and therefore their (bio)availability for the whole trophic chain. My researches are involved in this environmental topic and take part in the European Program INTERREG-III, Stardust. Three cross-border sites between France and Belgium have mainly been considered for this thesis: Scheldt, Lys and Spierre rivers. Trace metal analysis in the three sites sediments have pointed out high contamination by cadmium. However the metals (mainly Cd, Cu, Pb and Zn) are mostly trapped in the reduced sulphur pool in these sediments. Conversely, Co and Ni are less trapped in these sediments due to their higher availability. Several sediment and porewater quality indexes have been used and shown that Spierre sediments seem to have a low toxicity according to the high AVS concentrations whereas interstitial waters are more polluted because of the low water hardness. Furthermore, the DGT -AgI technique used for the determination of dissolved sulphides has been deployed successfully in the North Sea sediment core to emphasize the sëasonal effect on the sulphides production. ln the same way, our work on gold microelectrodes results finally in the monitoring on line of Zn and Pb concentration in Deùle river, and sorne preliminary measurements directly in the Deûle sediments.

Hochporöse Kohlenstoffaerogele, die über den Sol-Gel-Prozeß auf der Basis von Resorzin und Formaldehyd hergestellt werden, sind Werkstoffe mit beeindruckenden physikalischen Eigenschaften. Leider werden bisher nur geringe Mengen an Kohlenstoffaerogelen produziert und aus Kostengründen auf günstigere Materialien mit vergleichsweise schlechteren Eigenschaften zurückgegriffen. Um diesen Nachteil zu nivellieren lag die Motivation der vorliegenden Arbeit in der Entwicklung neuer Syntheserouten für Kohlenstoffmaterialien mit nanoskaliger Morphologie, wobei insbesondere auf kostengünstige Edukte und/oder einfache Prozessierung zurückgegriffen werden sollte. Als in Frage kommende Eduktsysteme wurden Zucker, sowie Hydroxybenzol-Formaldehyd-Derivate ausgewählt. Die hergestellten Kohlenstoffe wurden hauptsächlich mit Elektronenmikroskopie, Gassorption und Röntgenkleinwinkelstreuung (SAXS) charakterisiert. Um Fehlinterpretationen der experimentellen Daten für das neue Materialsystem zu vermeiden, war ein umfangreiches Wissen zu den Charakterisierungsmethoden und den diesen zugrundeliegenden physikalischen Prinzipien notwendig. Kohlenstoffpulver basierend auf sphärischen Resorzin-Formaldehyd Suspensionen und Sedimenten bilden eine völlig neue Möglichkeit zur Erzeugung von Kohlenstoffnanokugeln. Im Rahmen dieser Arbeit wurde deshalb systematisch der Bereich der Syntheseparameter im RF-System zu den nicht-monolithischen Parametersätzen hin vervollständigt. Anhand der bestimmten Daten konnte diese Stoffklasse umfassend und detailliert charakterisiert und interpretiert werden. Die Partikelgröße hängt im Wesentlichen von der Katalysatorkonzentration und in geringerem Maße von der Eduktmenge in der Startlösung ab. Die ermittelte untere Grenze der Partikelgröße aus stabilen kolloidalen Dispersionen beträgt ca. 30 nm. Größere Partikel als 5 µm konnten trotz Modifikation der Syntheseroute nicht erzeugt werden. Eine Abschätzung über den Aggregationsgrad der Kohlenstoffpulver wurde durchgeführt. Eine Beimischung von Phenol verringert in diesem System zum einen die Partikelgröße und erzeugt zunehmend nicht-sphärische Strukturen. Die aus Gassorption, SAXS und dynamischer Lichtstreuung (DLS) ermittelten Partikelgrößen stimmen gut überein. Bei der Pyrolyse schrumpfen die Partikel auf 84% des Ausgangswerts (Partikeldurchmesser). Ein Fokus dieser Arbeit lag in der Herstellung poröser Kohlenstoffe mit Phenol und Formaldehyd (PF) als Eduktbasis und unterkritischer Trocknung (Kohlenstoffxerogele). Um die Bandbreite der Eigenschaften der resultierenden Kohlenstoffxerogele zu erweitern, wurden zahlreiche Modifikationen der Syntheseparameter und im Herstellungsprozeß durchgeführt. Die Ergebnisse zeigen, daß im Eduktsystem Phenol-Formaldehyd in wäßriger Lösung mit Na2CO3 als basischem Katalysator prinzipiell poröse Xerogele herstellbar sind; allerdings verhindert eine ungewöhnliche Gelierkinetik (Flockenbildung statt Sol-Gel-Übergang) eine umfassende Interpretation des Systems, da die Reproduzierbarkeit der Ergebnisse nicht gewährleistet ist. Bei Phenol-Formaldehyd in wäßriger Lösung und NaOH als Katalysator kommt es meist zu einem Kollabieren des Gelnetzwerks während der Trocknung. Lediglich bei hohem Formaldehydüberschuß zeigt sich ein enger Bereich, in dem Xerogele mit geringer Dichte (rhomin = 0,22 g/cm3) und relevantem Mesoporenvolumen von bis zu 0,59 cm3/g synthetisierbar sind. Die interessanteste Kombination im PF-System ergibt sich mit HCl als Katalysator und n-Propanol als Lösungsmittel. Hier sind hochporöse Kohlenstoffxerogele mit geringen Dichten (rhomin = 0,23 g/cm3) und für Xerogele sehr hoher Mesoporosität von bis zu Vmeso = 0,85 cm3/g möglich. Damit ist es im Rahmen dieser Arbeit erstmals gelungen über konvektive Trocknung homogene hochporöse Xerogel-Formkörper auf PF-Basis zu synthetisieren. Aus der Überwachung des Sol-Gel-Prozesses mit Detektion der Soltemperatur konnten wichtige Erkenntnisse über exo- und endotherme Vorgänge gewonnen werden. Zudem zeigt die Zeitabhängigkeit der Soltemperatur Gemeinsamkeiten für alle untersuchten Hydroxybenzol-Formaldehyd-Systeme. So kann der Gelpunkt der Ansätze zuverlässig und auch reproduzierbar anhand eines zweiten lokalen Temperaturmaximums ermittelt werden, welches mit einer Gelpunktsenthalpie korreliert wird. Damit ist auch eine Prozeßkontrolle, z.B. für die Kombination mit Partikeltechnologien, möglich. Die zugrundeliegenden Strukturbildungsmechanismen, Sol-Gel-Prozeß einerseits und Trocknung andererseits, wurden in-situ mittels SAXS beobachtet und anhand der gewonnenen Daten diskutiert und bewertet. Eine vollständige Adaption des etablierten und akzeptierten Bildungsmechanismus von RF basierten Aerogelen (Partikelbildung aus Kondensationskeimen und Partikelwachstum) für das PF-System wird ausgeschlossen. Vielmehr scheint bei den untersuchten PF-Systemen auch eine Mikrophasenseparation als konkurrierender Prozeß zur Partikelbildung von Relevanz zu sein. / Highly porous carbon aerogels derived via the sol-gel-process based on the precursors resorcinol and formaldehyde are materials with impressive physical properties. In principle, they are suited for many applications (e.g. thermal insulations, components in electrochemical devices). Unfortunately, up to now, there are only small amounts of carbon aerogels available. Due to cost efficiency, cheaper materials with less favourable properties compared to carbon aerogels are used. To compensate for this disadvantage, the motivation for this work was the development of new synthesis routes for carbon materials with nanostructured morphology, applying in particular cheap precursors and/or simple processing. As precursor systems, sugar as well as hydroxybenzene-formaldehyde-derivatives were chosen. The produced carbons were characterised in particular by electron microscopy, gas sorption and small-angle X-ray scattering (SAXS). To avoid misinterpretation of the experimental data of the new materials system, extensive knowledge concerning the characterization methods and their underlying physical principles are essential. Carbon powders based on spherical particles derived from suspensions and sediments of resorcinol-formaldehyde (RF) solutions establish a completely new possibility to generate carbon nanospheres. Within the framework of this thesis the range of the synthesis parameters of the RF-system towards the non-monolithic parameter sets was therefore systematically completed. These materials were characterized and interpreted extensively and in detail by using the derived experimental data. The particle size depends essentially on the catalyst concentration rather than on the amount of precursors in the initial solution. The lower limit particle size derived from stable colloidal suspensions is about 30 nm. Larger particles than 5 µm could not be synthesized, even when modifying the synthesis route. An estimate for the level of aggregation of the carbon powders was determined. Admixing of phenol decreases the particle size in this system and generates increasingly non-spherical structures. The evaluated particle sizes derived from gas sorption, SAXS and dynamic light scattering (DLS) are in good agreement with each other. During pyrolysis, the particles shrink to 84% of the initial value (particle size). One goal of this work was the synthesis of porous carbons with phenol and formaldehyde (PF) as precursors and subcritical drying (carbon xerogels). To extend the possible properties of the resulting carbon xerogels, several modifications of the synthesis parameters as well as in the production process were conducted. The results show, that with the precursors phenol-formaldehyde in aqueous solution using Na2CO3 as catalyst, porous xerogels can in principle be synthesized. However, the unusual gelation kinetics (flake forming instead of sol-gel-transition) prevents a detailed interpretation of this system, because the reproducibility of the results can not be ensured. With the system phenol and formaldehyde in aqueous solution using NaOH as catalyst, the gel network mostly collapses during drying. Only with excess formaldehyde a range in the synthesis parameters exists, where xerogels with low density (rhomin = 0,22 g/cm3) and relevant mesopore volume of up to 0,59 cm3/g can be synthesized. The most interesting combination of PF is with HCl as catalyst and n-propanol as solvent. With this system, highly porous carbon xerogels with low densities (rhomin = 0,23 g/cm3) and for xerogels high mesoporosity of up to Vmeso = 0,85 cm3/g can be synthesized. Hence, within the framework of this thesis highly porous monolithic xerogels based on PF as precursors in combination with subcritical drying have been successfully synthesiszed for the first time. Monitoring of the sol-gel-process by detection of the sol temperature provided important information about exo- and endothermal reactions. Moreover, the temperature dependence of the sol shows similarities for all investigated hydroxybenzene-formaldehyde combinations. The gelling point of the precursor systems can be reproduced reliably by determining a second local maximum of the sol temperature, which can be correlated with an enthalpy of gelation (second order process). By this way, a process control is possible, e.g. for the combination with particle technologies. The basic mechanisms of structure formation, i.e. the sol-gel-process on the one hand and the subcritical drying on the other hand were monitored in-situ by SAXS and discussed on the base of the obtained data. A complete adaptation of the established and accepted structure formation mechanism of RF based aerogels (forming and growing of particles by) can be ruled out for the PF-system. Moreover, microphase separation seems to be a relevant competing process for the particle forming in the PF-system.

In der vorliegenden Arbeit wurden durch den Sol-Gel-Prozeß hergestellte hybride Sole, Xerogele und Schichten mit Hilfe der Raman-Spektroskopie untersucht. Dazu wurden zunächst die schwingungsspektroskopischen Zuordnungen für verschiedene Alkoxysilanen ergänzt und zusammengefasst. Anschließend wurde die Hydrolyse vom Vinyltriethoxysilan (VTES) durch FT-Raman-Spektroskopie vom Sol bis zum Xerogel verfolgt. Weitere Untersuchungen an verschiedenen Xerogelen lieferten neue Erkenntnisse über charakteristische Raman-Banden des anorganischen Netzwerkes. Der zweite Teil dieser Arbeit richtete sich auf konfokale Raman-mikrospektroskopische Untersuchungen hybrider Schichten bezüglich der anorganischen und organischen Vernetzung. Zunächst wurden Polymersubstrate untersucht. Es wurde experimentell festgestellt, dass die axiale Auflösung eines konfokalen Raman-Mikrospektrometers tatsächlich niedriger ist als bisher in der Literatur angenommen wurde. Bei Mikro-Raman-Untersuchungen an verschiedenen Schichtsystemen hat sich herausgestellt, dass die Schwingungsmoden des anorganischen Netzwerks im niederfrequenten Raman-Bereich leicht detektierbar sind. Die Lage der charakteristischen sogenannten T3/Q3-Bande im Raman-Spektrum der UV-gehärteten Probe deutet allerdings auf einen niedrigeren Kondensationsgrad hin, als beim langsam luftgetrockneten Xerogel, was mit Hilfe von 29Si-Festkörper-NMR-Messungen bestätigt wurde. Darüber hinaus konnte festgestellt werden, dass die Schichten einen höheren Kondensationsgrad als die gleich behandelten Volumenproben aufweisen. Es wurde gezeigt, dass die gewonnenen Raman-spektroskopischen Erkenntnisse für die Erforschung und die Lösung von Vernetzungsproblemen hilfreich sein können. Nach einem kurzen Überblick der Mechanismen der organischen Vernetzung wurden zunächst thermisch-hartbaren Schichtsysteme auf Glycidyloxypropyltrimethoxysilan-Basis durch Raman-Mikrospektroskopie untersucht. Die quantitative Auswertung des Umsetzungsgrades erfolgte nach einer Bandenanalyse der Ringatmungsschwingung des Epoxidrings. Es stellte sich heraus, dass die Polyadditionsreaktion nur sehr begrenzt stattfindet. Dagegen ist die Anhydridhärtung unter den gleichen Bedingungen deutlich effizienter. Daneben wurde gezeigt, dass die an Volumenproben erhaltenen Ergebnisse, in Bezug auf die organische Vernetzung, nicht auf die entsprechenden Schichten übertragen werden können. Bei den untersuchten UV-härtbaren Schichtsystemen konnte der Umsetzungsgrad mittels einer Bandenanalyse der reaktiven Gruppen erfolgreich ermittelt werden. Die Reaktivität der ungesättigten Gruppen, wenn sie einer radikalischen Polymerisation ausgesetzt sind, folgt der Reihe: Allyl < Vinyl < Acrylat. Die Thiol-En-Addition bei den VTES / Mercaptopropyltrimethoxysilan-Schichtsystemen führt zu höheren Umsetzungsgraden der Vinylgruppen bei gleichen Bedingungen. Die Kinetik der Polymerisationsreaktion spielt also eine entscheidende Rolle bei der Vollständigkeit der organischen Vernetzung. Ein weiterer Teil dieser Arbeit richtete sich auf die Ermittlung der mechanischen Eigenschaften von hybriden Schichten und deren Korrelation mit spektroskopischen Daten. In allen untersuchten Schichtsysteme demonstrierte die chemische Variation der beteiligten Komponenten, dass die organische Vernetzung und das anorganische Netzwerk stark miteinander wechselwirken. Somit ensteht ein Synergieeffekt, welcher der hybridpolymeren Schicht ihre mechanische Beständigkeit verleiht. Schließlich stellte sich heraus, dass die Mikrohärte mit den spektroskopischen Daten verknüpft werden kann. Bei allen Schichtsystemen zeigte sich eine starke Abhängigkeit von Mikrohärte und Härtungsdauer. Alle thermisch gehärteten Schichten weisen eine sehr hohe Abriebfestigkeit sowie eine sehr gute Adhäsion auf Glas und Kunststoff auf, was ihren Einsatz als kratzfeste Schichten nahelegt. Die UV-härtbaren Schichtsysteme weisen zwar eine hohe Abriebfestigkeit auf, haften aber schlecht auf Polycarbonaten (PC). Die haftungs- / enthaftungsrelevanten Vorgänge spielen sich an der Grenzflächen oder einer Interphase geringer Ausdehnung statt und können daher Raman-miskrospektroskopisch nicht erfasst werden. TEM-Aufnahmen zeigten deutlich, dass die schlechte Haftung auf PC auf die unzureichende Benetzung der Schicht auf dem Substrat zurückzuführen ist. Weiterhin konnte festgestellt werden, dass der Zusatz von einem Acrylat als Additiv zur Bildung einer Interdiffusionsschicht führt, die die Haftung auf PC verbessert. Die Untersuchungen der Bewitterungsbeständigkeit beschränkten sich auf zwei UV-härtbare Schichtsysteme. Die Mikro-Raman-Spektren zeigten, dass zunächst die organischen Komponenten der hybriden Schicht angegriffen und geschädigt werden. Der Schutzeffekt von Lichtstabilisatoren und UV-Absorbern auf die organischen Komponenten des hybriden Netzwerks konnte ebenfalls spektroskopisch bestätigt werden. / The present work deals with the Raman spectroscopic study of hybrid coating formulations prepared by the sol-gel process. First vibrational spectroscopic assignments for several alkoxysilanes were completed and presented. The hydrolysis of vinyltriethoxysilane (VTES) was followed from the sol to the xerogel state by means of FT-Raman spectroscopy. New insights about characteristic Raman bands of the inorganic network were gained from further investigations. The second part of this work deals with the confocal Raman microscopic study of the inorganic condensation and organic cross-linking of hybrid coatings. For this purpose several polymeric substrates were studied. It was experimentally demonstrated that the axial resolution of the confocal Raman microspectrometer is actually lower than usually claimed in the literature. The confocal Raman microscopic study of different coating systems showed that the vibrational modes of the inorganic network may be easily detected in the low wavenumber region. The position of the characteristic so-called T3/Q3 band for the UV-cured samples indicates a lower inorganic condensation as compared to the air-dried xerogel. This was confirmed by means of the corresponding 29Si solid state NMR spectra. Besides, it was shown that the degree of condensation is higher in the coatings as in the bulk samples. The Raman microscopic measurements may help to investigate and solve the condensation problems during development of coating sols. After a reminder of the mechanisms involved in the organic cross-linking of epoxy-based systems, the thermally cured coating system containing Glycidyloxypropyltrimethoxysilane (GPTMS) was first studied. The analysis of the characteristic ring-breathing mode of the epoxy groups was used to calculate the conversion of the epoxy groups. The conversion of the epoxy groups through a thermal polyaddition was found to be very low. In contrast to that, the thermal curing in the presence of an anhydride was much more efficient under the same conditions. Furthermore it must be pointed out that the state of condensation and organic cross-linking in thin coatings must not be derived from the spectral results obtained for the corresponding bulk samples. The conversion of the unsaturated groups may be calculated for all UV-curable coating systems with the help of their corresponding Raman bands. The reactivity of the unsaturated groups towards radical polymerisation was found to follow the series: allyl < vinyl < acrylate. In comparison, the thiol / ene addition (VTES / Mercaptopropyltrimethoxysilane coatings) leads to a higher conversion degree of the vinyl groups under the same curing conditions. This result shows that the kinetics of the polymerisation reaction employed has a decisive influence on the completeness of the organic cross-linking. A further part of this work aimed at the investigation of the mechanical properties of the hybrid films. It was proceeded with some variation of the chemical formulation, which finally revealed a strong coupling effect existing between organic cross-linking and inorganic network. This synergic effect is undoubtedly responsible for the mechanical resistance of the hybrid coatings. Finally, it was found that the micro-hardness may be correlated with the Raman spectroscopic data, the quantitative estimation of the organic cross-linking degree beeing a function of the curing conditions and chemistry for any studied hybrid coating system. A strong dependence between the micro-hardness and the curing time was noted. All the thermally curable coatings were highly resistant against abrasion and generally possess very good adhesion properties on glass and plastic, so that they have a great potential for scratch-resistant coating applications. UV-curable coating systems, while having a good abrasion resistance as well, showed poor adhesion on polycarbonate (PC). Adhesion relevant processes occur at the interface or in a region of small dimension, thus are not accessible through Raman microspectroscopy. The TEM micrographs showed that the lack of adhesion on polycarbonate was essentially due to the poor wettability of the coating sol on the polycarbonate substrate. The TEM micrographs of coating systems containing an acrylated additive showed the presence of an interpenetrating layer that is considered to be responsible for the good adhesion on polycarbonate. The investigations on the weathering stability of the hybrid coatings were restricted to two UV-curable coating systems. The micro-Raman spectra showed that mainly the organic cross-links would be affected and damaged through the accelerated weathering. The addition of light stabilizers and UV-absorbers clearly lead to a protection of the organic cross-links of the hybrid coatings as shown spectroscopically.

Nach dem Sol-Gel-Verfahren wurden carbonsäuremodifizierte Mullitvorstufen hergestellt und charakterisiert. Dabei wurde die Kettenlänge der zur Synthese der Sole verwendeten Carbonsäuren variiert. Es zeigte sich, dass die säurekatalysierte Kondensation der Siliciumkomponente zu linearen, oligomeren Si-O-Si-Ketten in Propionsäuresolen bereits bei Raumtemperatur erfolgt. In Hexan- und Nonansäuresolen ist dagegen aufgrund der größeren sterischen Abschirmung der Siliciumspezies durch über Wasserstoffbrückenbindungen gebundene Carbonsäuren keine Kondensation der Monomere möglich. Beim Einengen der Sole zu einem Pulver resultietren amorphe oder teilkristalline Mullitvorstufen, die sich in ihrer Struktur und ihrem Kristallisations- und Verdichtungsverhalten unterschieden. / Mullite precursors, modified by carbonic acids, were synthesised by the Sol-Gel process and characterised. Therefore, carbonic acids of different lengths were used for the synthesis of the sols. It was shown that in propionic acid sols, acid catalysed condensation of linear, oligomeric Si-O-Si chains occurred at room temperature. In contrast, the hexanoic and nonanoic acid sols showed no condensation at room temperature, because the silica component is sterically shielded by the carbonic acid. The evaporation of the solvents in the sol resulted in amorphous or partly crystalline mullite powders with different structure and differences in the behaviour of crystallisation and densification.

A radioterapia externa pós-operatória em mulheres diagnosticadas com câncer de mama em estágio inicial é tido como um procedimento padrão, no entanto durante o planejamento para irradiação do volume alvo as possíveis incertezas dosimétricas introduzidas dado o movimento respiratório intrínseco da paciente são desconsideradas. Este estudo avalia não apenas a influência da respiração na distribuição tridimensional da dose, mas como essa distribuição se modifica dado a técnica radioterápica empregada para o tratamento. Três técnicas de planejamento foram analisadas: a radioterapia conformacional tridimensional (3D-RT) com filtros, a radioterapia com intensidade modulada (IMRT) usando planejamento direto e o IMRT inverso. A fim de simular o movimento de contração e expansão da caixa torácica, utilizou-se uma plataforma com amplitudes de oscilação pré-determinadas, sendo a frequência de oscilação provida por uma fonte de tensão variável. Para simular a mama usou-se objetos simuladores semiesféricos preenchidos com gel dosimétrico (MAGIC-f). Os planejamentos para cada técnica foram realizados sobre a mesma tomografia computadorizada (CT) do objeto simulador preenchido com água no modo estático. Foram produzidos três lotes de dosímetro gel para o projeto, cada lote foi irradiado com uma técnica radioterápica diferente, sendo que cada lote inclui cinco objetos simuladores e um conjunto de nove tubos de calibração preenchidos com gel MAGIC-f. O primeiro dos objetos simuladores é utilizado como referência, o segundo é irradiado no modo estático, os demais são irradiados em diferentes amplitudes, respectivamente: 0,34 cm, 0,88 cm e 1,22 cm. A informação volumétrica de dose foi obtida utilizando imagens por ressonância magnética nuclear (IRMN), para cada lote foram adquiridos IRMN com sequência multi spin echo e os mapas de relaxometria, que são associados à dose, foram extraídos em um software desenvolvido e aprimorado pelo nosso grupo de pesquisa. A comparação quantitativa dos mapas de relaxometria dos objetos simuladores em movimento em relação ao modo estático foi realizado pelo índice gamma tridimensional (3% / 3mm / 15% Threshold). Para o 3D-RT a porcentagem de pontos aprovados do objeto estático em relação ao oscilante na amplitude de 0,34 cm foi de 96,44%, para amplitude de 0,88 cm foi de 93,23% e para amplitude de 1,22 cm foi de 91,65%. Para o IMRT direto a porcentagem de pontos aprovados do objeto estático em relação ao oscilante na amplitude de 0,34 cm foi de 98,42%, para amplitude de 0,88 cm foi de 95,66% e para amplitude de 1,22 cm foi de 94,31%. Para o IMRT inverso a porcentagem de pontos aprovados do objeto estático em relação ao oscilante na amplitude de 0,34 cm foi de 94,49%, para amplitude de 0,88 cm foi de 93,51% e para amplitude de 1,22 cm foi de 86,62%. A partir dos resultados, infere-se que a movimentação respiratória de baixa amplitude, para tratamentos de câncer de mama, não é um fator preocupante para a rotina clínica, porém o aumento da amplitude da oscilação aumenta a inomogeneidade de dose e pode afetar os parâmetros dosimétricos da cobertura do volume alvo em relação ao planejamento do tratamento. Observou-se em conjunto que a distribuição de dose se modifica claramente com a técnica em uso e no caso do IMRT inverso para amplitude de oscilação de 1,22 cm a aprovação no índice gamma foi menor que 90% / External postoperative radiotherapy in women diagnosed with early stage breast cancer is considered as a standard procedure, however during planning for target volume irradiation as possible dosimetric uncertainties reabsorption of the patient\'s intrinsic respiratory movement are disregarded. This study evaluates not only the influence of respiration on the three-dimensional distribution of the dose but how this distribution is modified due to the radiotherapy technique used for treatment. Three planning techniques were analyzed: three-dimensional conformational radiotherapy (3D-RT) with filters, intensity-modulated radiotherapy (IMRT) using direct planning and inverse IMRT. In order to simulate the movement of contraction and expansion of the chest wall, a platform with predetermined oscillation amplitudes was used, the oscillation frequency was provided by a variable voltage source. To simulate the breast, semi-spherical simulator objects filled with dosimetric gel (MAGIC-f) were used. The plannnings for each technique were performed on the computerized tomography (CT) of the simulator object filled with water in static mode. Three batches of gel dosimeters were prepared for the project, each batch was irradiated with a different radiothermic technique and comprised five simulator objects and a set of nine calibration tubes filled with MAGIC-f gel. The first simulator objects is used as reference, the second is irradiated in the static mode, the others are irradiated using different amplitudes, respectively: 0,34 cm, 0,88 cm and 1,22 cm. Volumetric dose information was obtained using Nuclear Magnetic Resonance Imaging, each batch was scanned with a multi spin echo sequence and the dose-related relaxometry maps were extracted in a software developed and improved by our Group of research. The quantitative comparison of the relaxometry maps of the moving simulator objects with respect to the static mode was performed by the three-dimensional gamma index (3% / 3mm / 15% threshold). For the 3D-RT, the percentage of approved points of the static object with respect to the oscillator in the amplitude of 0.34 cm was 96.44%, for amplitude of 0.88 cm was 93.23% and for amplitude of 1.22 cm was 91.65%. For the direct IMRT the percentage of approved points of the static object in relation to the oscillator in the amplitude of 0.34 cm was 98.42%, for amplitude of 0.88 cm was 95.66% and for amplitude of 1.22 cm was 94.31%. For the inverse IMRT, the percentage of approved points of the static object in relation to the oscillator in the amplitude of 0.34 cm was 94.49%, for amplitude of 0.88 cm was 93.51% and for amplitude of 1.22 cm was 86.62%. From the results, it is inferred that a low-amplitude respiratory movement, for breast cancer treatments, is not a worrying factor for clinical routine, however, increasing the amplitude of the oscillation increases the inomogeneity of the dose and this affects the dosimetry parameters of the target volume coverage. It was observed that the dose distribution changes with the technique in use and in the case of the inverse IMRT for amplitude of oscillation of 1.22 cm, less than 90% of points were approved in the gamma index evaluation

Foram produzidos xerogéis e filmes finos de SnO2 dopados com Er e codopados com Yb pelo processo sol-gel, sendo usada a técnica de molhamento (“dip-coating") para a produção de filmes finos. Propriedades ópticas, estruturais e elétricas são analisadas neste material, destacando-se espectros de emissão e excitação em xerogéis de SnO2:Er e SnO2:Er,Yb, os quais revelam algumas peculiaridades a respeito da incorporação de Er na matriz SnO2. São detectadas duas famílias de Er em SnO2, na primeira Er3+ entra substituindo Sn4+ na estrutura cassiterita, e na segunda fica segregado na superfície das partículas. Processos de transferência de energia de Yb3+ para Er3+ são efetivos nestas amostras. Medidas de difração de raios X mostram um aumento do tamanho do cristalito à medida que se aumenta a temperatura de tratamento térmico. O oposto ocorre quando o dopante é introduzido, pois um aumento na concentração de Er proporciona uma diminuição no tamanho do cristalito. Usando experimentos de caracterização elétrica, é identificada a ação aceitadora de Er em SnO2 tipo-n, pois se observou um aumento de até 5 ordens de grandeza na resistividade de filmes dopados com Er comparados à amostras não-dopadas. Resultados de decaimento da condutividade fotoexcitada em filmes finos, também dão indícios deste cárater aceitador, já que a remoção da iluminação com a linha 266nm (4o harmônico de um laser Nd:YAG), induz a um decaimento da condutividade. Além destas técnicas, foram empregadas ainda absorção óptica, a qual mostrou transparência acima de 80% no visível; reflexão especular de raios X, indicando espessura de 6,3nm/camada, rugosidade de 1,55nm e 39% de porosidade. Usando medida de resistência e corrente-voltagem em função da temperatura, observou-se que os modelos de emissão Schottky e Poole-Frenkel são obedecidos para baixos e altos campos elétricos, respectivamente.

A presente dissertação estudou as potencialidades e limitações na elaboração de sensores híbridos através do encapsulamento do indicador de pH púrpura de bromocresol em matrizes à base de sílica, de polímero de acrilato e de suas combinações. Os sensores sólidos resultantes foram avaliados frente a vapores de gases alcalinos. Ao total foram realizadas seis rotas distintas, alternando o meio catalítico e combinando sucessivamente as diferentes matrizes de encapsulamento, totalizando 11 sensores sintetizados. As características e propriedades estruturais, morfológicas e texturais dos diferentes sensores foram correlacionados com sua performance diante de vapores alcalinos. Do conjunto de sensores que apresentaram melhor performance foram realizados testes de compatibilidade com poliolefinas e imagens de microtomografia de Raios X. Os sensores híbridos foram caracterizados por um conjunto de técnicas complementares compreendendo espectroscopia molecular de refletância difusa no ultravioleta-visível, espectroscopia no infravermelho, microscopia eletrônica de varredura, microscopia confocal de varredura a laser, espalhamento dinâmico de luz e espalhamento de Raios X a baixo ângulo. Complementarmente, foram avaliados o tempo de resposta ao vapor de amônia, quantificação da mudança cor e a reversibilidade dos sensores. Os resultados obtidos foram correlacionados estatisticamente e foi possível separar- em três grupos. A partir dos dados adquiridos foi possível determinar que o comportamento dos sensores é influenciado pelo tipo de síntese adotada. Os dados revelam que os sensores à base de sílica apresentaram resultados melhores que aqueles com matriz polimérica: tempo de resposta de 4:50 minutos (versus 11:50 para matriz polimérica) e menor taxa de reversibilidade, embora as alterações de tonalidade de cor sejam semelhantes (ΔE*ab, de 27,8 e 21,0, respectivamente, para matrizes de sílica e de polímero. A compatibilidade com poliolefina (polipropileno) mostrou dois comportamentos distintos: os sensores à base de sílica apresentaram grandes aglomerados centralizados e poucos dispersos, já os poliméricos apresentaram uma dispersão homogênea ao longo de toda matriz. Os silicatos apresentaram melhores resposta aos gases da deterioração de peixe, enquanto para amônia os poliméricos obtiveram uma performance melhor. / The present master dissertation investigated the potentialities and limitations in the preparation desing of hybrid sensors through the encapsulation of the pH indicator bromocresol purple within silica - based matrices, acrylate polymer and their combinations. The resulting solid sensors were evaluated against alkaline gases and vapors. In total, six different routes were carried, alternating the catalyst and successively combining the different encapsulating matrices, totalizing 11 synthesized sensors. The characteristics and structural, morphological and texture properties of the different sensors were correlated with their performance in the presence of alkaline vapors. Out of the set of sensors that presented the best performance, such systems were evaluated by compatibility tests with polyolefin and X-ray tomography. The hybrid sensors were characterized by a set of complementary techniques, namely ultraviolet-visible diffuse reflectance molecular spectroscopy, Fourier Transform infrared spectroscopy, scanning electron microscopy, laser scanning confocal microscopy, light dynamic scattering and small angle x-ray scattering. In addition, the response time to ammonia vapor, quantification of the color change and the reversibility of the sensors were evaluated. The results were statically correlated that allowed separating them into a set of three groups. From the acquired data it was possible to determine that the performance of the sensors is influenced by the type of adopted synthesis. Data show that silica-based sensors presented better results than those with polymer matrix: response time of 4:50 minutes (versus 11:50 for polymer matrix) and lower rate of reversibility, although changes in color tone are similar (ΔE * ab, 27.771 and 21.011, respectively for silica and polymer matrices.) The compatibility with polyolefin (polypropylene) showed two distinct performances, the silicate-based sensors presented large centralized agglomerates with few dispersed particles, while the polymers have showed a homogeneous dispersion along the whole matrix. The silicates exhibited better response to the gases of the fish under deterioration, while for ammonia the polymers achieved better performance.

O presente trabalho descreve o desenvolvimento de um método analítico baseado na pré-concentração em fase sólida em fluxo de íons cobalto com posterior determinação por espectrofotometria. Como adsorvente sólido empregou-se a sílica gel modificada com 2-aminoetil-3-aminobutilmetildimetoxisilano (AAMDMS) e impressa ionicamente com o íon Co+2 (SGI). O sistema de pré-concentração em fluxo é baseado na retenção catiônica dos íons cobalto em uma mini-coluna preenchida com SGI, com conseqüente eluição com HNO3 0,5 mol L-1. Os íons cobalto eluídos reagem posteriormente com o complexante 1-(2-piridilazo)-2-naftol (PAN), formando um complexo de cor verde detectado espectrofotometricamente em 575 nm. As condições otimizadas foram: pH da amostra (9,2); concentração do tampão (amoniacal) da amostra (0,01 mol L-1); concentração do surfactante (LSS) (3,0 mmol L-1); vazão de pré-concentração (9,0 mL min-1); concentração do tampão (amoniacal) da solução do PAN (0,75 mol L-1); concentração do PAN (100 mmol L-1); pH da solução do PAN (10,2); comprimento da bobina reacional (225 cm); vazão total de eluição (7,0 mL min-1). A seletividade da SGI frente os íons cobalto foi atestada por meio da constante de seletividade relativa K’(KSGI/Kbranco), rendendo valores de 10,9 e 10,2 para (KSGI/ K sílica funcionalizada) e (KSGI/ Ksílica gel), respectivamente no sistema Co2+/Ni2+. Para o sistema Co2+/Cu2+ os valores encontrados foram 6,4 e 11,4. Além disso, foi realizado teste de interferência por meio de soluções binárias contendo diferentes proporções cobalto:interferente [1:1, 1:10, 1:100 (m/m)]. Os íons avaliados foram Ni2+, Cu2+, Fe2+, Pb2+, Cd2+, Mn2+, Zn2+, Cr3+ e, com exceção do íon zinco, na proporção 1:1 nenhum interferência foi observada. A precisão (n=10, repetibilidade) para os padrões de 10,0 e 90,0 μg L-1 rendeu desvios padrão relativos de 2,63 e 1,5%, respectivamente. O método apresentou os respectivos limites de detecção e quantificação de 0,51 e 1,71 μg L-1 e um fator de pré-concentração de 7,21 vezes. O método proposto foi aplicado em amostras de água, urina e material certificado de referência. / The present work describes the development of analytical method based on solid phase flow preconcentration of cobalt ions with further determination by spectrophotometry. Modified silica gel with 2-aminoethyl-3- aminobutylmethyldimethoxysilane (AAMDMS) and ionically imprinted with Co2+ ions (ISG) was employed as solid adsorbent. The flow preconcentration system is based on cationic retention of cobalt in a mini-column filled with ISG, with further elution with 0.5 mol L-1 HNO3. The cobalt ions eluted react subsequently with the complexant 1- (2-pyridylazo)-2-naphthol (PAN), forming a green complex detected spectrophotometrically at 575 nm. The optimized conditions were: sample pH (9.2); buffer (amoniacal) concentration of the sample (0.01 mol L-1), surfactant (SLS) concentration (3.0 mmol L-1); flow rate preconcentration (9.0 mL min-1); buffer solution concentration of PAN (0.75 mol L-1); PAN concentration (100 mmol L-1), pH of PAN solution (10.2); length of reaction coil (225 cm), total elution flow rate (7.0 mL min-1). The selectivity of ISG towards cobalt ions was attested by the constant selectivity for K'(KSGI / Kblank), yielding values of 10.9 and 10.2 for (KSGI / K functionalized silica) and (KSGI / Ksilica gel), respectively in the Co2+/Ni2+ system. For the system Co2+/Cu2+ the values were 6.4 and 11.4. Moreover, interference testing was performed by binary solutions containing different cobalt:interferent proportions [1:1, 1:10, 1:100 (m/m)]. The evaluated ions were Ni+2, Cu +2, Fe2+, Pb+2, Cd+2, Mn +2, Zn +2, Cr+3, and except by zinc, in 1:1 proportion no interference was observed. The precision (n=10, repeatability) for the standards 10.0 and 90.0 μg L-1 yield relative standard deviation of 2.63 and 1.5%, respectively. The method showed the respective detection and quantification limits of 0.51 and 1.71 μg L-1 and a preconcentration factor of 7.21. The proposed method was applied in water samples, urine and certified reference material.

In this thesis, glucose responsive hydrogels based on cross-linked dextran molecules were studied to determine the diffusion rate of an insulin analogue. Investigations of the interaction between concanavalin A and dextran, both in free solution and in the form of glucose responsive hydrogels were conducted. The free solution results have shown that there is an increase of association constant between concanavalin A and dextran when the molecular mass of the dextran is increased. Free solution viscometric tests have shown that increasing the molecular mass or the concentration of the dextran increases the viscosity. The hydrogels have been shown to form for dextrans of molecular mass 43kD or greater. Experiments conducted with hydrogel membranes in a diffusion cell have shown that the batch to batch reproducibility of hydrogel transport properties is low. However, clear evidence of glucose enhanced transport was obtained and these results were compared with predictions obtained from a theoretical model of gel permeability that accounts for competitive displacement of affinity cross links. Oscillatory rheological tests of gelation mixtures which showed an increase in complex viscosity at the gel point with increasing molecular mass of dextran were in agreement with empirical observations that gels formed from the highest molecular mass dextrans were more physically robust and easier to handle. Swelling rate experiments have shown that the rate of hydration of a hydrogel in the presence of glucose is decreased due to the osmotic pressure of the glucose. This work has shown that the multivalent nature of concanavalin A may not be a necessary pre-requisite for this type of hydrogel due to spatial constraints decreasing the number of potential affinity bonds per tetramer. In-house production of more tightly defined dextrans might be expected to reduce heterogeneity and improve the reproducibility of this type of hydrogel membrane.

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