Introdução - A quantidade de flúor ingerida, proveniente de todas as fontes, durante o período crítico de formação dos dentes, é o principal fator de risco para a fluorose dentária. Dentre estas fontes estão a água fluoretada, o dentifrício fluoretado e os alimentos, bebidas, fórmulas e suplementos infantis. Considerando-se que a fluorose dentária tem aumentado em todas as regiões é importante avaliar, além da água e do dentifrício, também a contribuição diária do consumo alimentar das crianças e a concentração de flúor nesses itens alimentares para a ingestão de flúor. Objetivo - Descrever o consumo alimentar de crianças de 2 a 6 anos, com relação ao flúor. Métodos - Foram avaliadas 379 crianças, de 2 a 6 anos, faixa etária de risco para fluorose, residentes em Bauru - São Paulo, município com fluoretação artificial da água de abastecimento público. A amostragem foi estratificada por setor, baseando-se no Plano Diretor do Município. O consumo alimentar foi avaliado pelo Questionário de Freqüência Alimentar Semiquantitativo, aplicado aos pais ou responsáveis, e a concentração de flúor nos itens alimentares a partir de análises laboratoriais. As crianças foram classificadas quanto à ingestão diária de f1úor de acordo com a Dietary Reference Intakes. Resultados - Dentre os 70 itens alimentares, o arroz, a água de abastecimento público e o leite foram os mais consumidos; o chá preto, o leite em pó de soja diluído com água de abastecimento público e o biscoito Danyt\'s® apresentaram maior concentração de flúor; a água de abastecimento público, o refrigerante Coca-Cola® e a batata frita representaram maior contribuição diária para ingestão de flúor. Os itens alimentares mais consumidos apresentaram, em média (±DP), concentração de flúor (0,015 ± 0,028 mgF/porção) significantemente menor (p = 0,03) que os menos consumidos (0,107 ± 0,162 mgF/porção). Os itens alimentares com maior concentração de flúor contribuíram significantemente (p < 0,001) para a ingestão do halogênio (0,018 ± 0,037 mgF/dia). A média da ingestão de flúor por meio dos alimentos sólidos e líquidos, da água e da escovação foi de 0,017 ± 0,016; 0,011 ± 0,004 e 0,036 ± 0,028 mgF/kg peso/dia, respectivamente, totalizando 0,064 ± 0,035 mgF/kg peso/dia. Das 379 crianças, 31,2% apresentaram risco de fluorose. O dentifrício e os itens alimentares (sólidos, água e outros líquidos) contribuíram com 57% e 43%, respectivamente, para a ingestão de flúor. Conclusão - O dentifrício foi a principal fonte para a ingestão de f1úor pelas crianças, porém, a concentração desse halogênio nos itens alimentares contribuiu significantemente para a ingestão, representando risco para f1uorose dentária. / The quantity of fluoride ingested, deriving from all sources, during the critical period of formation of the teeth, is the main factor of risk for the dental fluorosis. Among this sources, we have the fluoridated water, the fluoridated dentifrice and the food, drinks, chemical formula and the infant supplements. Taking into consideration that the dental fluorosis has increased in all regions, it is important to evaluate it, besides the water and the dentifrice, the daily contribution of children\'s food consumption and the concentration of fluoride in these food items for the ingestion of fluoride. Objective - Describe the food consumption of children from 2 to 6 years old, relationg to fluoride. Methods - 379 children were evaluated at risking ages for fluorosis, residents in Bauru - São Paulo, district with artificial f1uoridation. The sampling was stratified by sector, based on the Director\'s Plan of the District. The food intake was evaluated by the Food Frequency Semiquantitative Questionnaire, applied on parents or responsable one, and the concentration of fluoride on the food items from analyses in laboraties. The children were classified based on theis daily ingestion of fluoride according to the Dietary Reference Intakes. Results - Among the 70 food items, rice, public water supply and the milk were the most consumed ones; the black tea, the soybean powdered milk diluted in public water and the biscuit Danyt\'s® presented the gratest daily contribution for the ingestion of fluoride. The most consumed food items present, in average (± DP), concentration of fluoride (0,015 ± 0,028 mg F / portion), significantly lower (p = 0,03) that the less consumed (0,107 ± 0,162 mgF/portion). The food items with the greatest concentration of fluoride contributed significantly (p < 0,001) for the ingestion of the mineral (0,018 ± 0,037 mgF/day). The average amount of fluoride ingestion taken from the solid food and the liquid ones (except water) coming from the water and the teeth brushing was 0,017 ± 0,016; 0,011 ± 0,004 and 0,036 ± 0,028 mgF/kg weight/day, respectively, totalizing 0,064 ± 0,035 mgF/kg weight/dia. 31,2% of the 379 children presented risk of fluorosis. The dentifrice and the food items (solid, water and other liquids) contributed with 57% and 43%, respectively, for the ingestion of fluoride. Conclusion - The dentifrice was the main source for the ingestion of fluoride, by the children, however, the concentration of this mineral in food items contributed significantly for the ingestion by the children, representing risk for dental fluorosis.

Ziel der vorliegenden Promotionsarbeit war die Entwicklung einer Methode zur Quantifizierung saurer Zentren auf Festkörperoberflächen mittels 15N-Festkörper-NMR-Spektroskopie von adsorbierten Pyridinmolekülen. Die 15N-Festkörper-NMR von adsorbiertem Pyridin ermöglicht die Unterscheidung verschiedener Arten von sauren Zentren, wie Lewis- und Brønsted-Zentren. Die Bestimmung der Art und der Konzentration auftretender saurer Zentren ist entscheidend, um die katalytische Aktivität fester Katalysatoren in einer Reaktion zu verstehen. Da 15N-NMR-Messungen zumeist zeitaufwendig sind, wurde in dieser Arbeit eine zeitoptimierte Messroutine entwickelt, die auf der Messung von 15N-Einzelpuls-Spektren mit kurzen Pulswiederholzeiten beruht. Um diese Spektren quantitativ auswerten zu können, müssen die detektierten NMR-Signale bezüglich ihrer T1-Relaxation korrigiert werden. Zudem treten in 15N-Einzelpuls-NMR-Spektren oft starke Störungen der Basislinie auf. Zur Unterdrückung dieser Störsignale wurde die EASY-Methode entwickelt, die auf der Messung von zwei schnell aufeinander folgenden Spektren basiert. Mittels dieser Methode können auftretende Störsignale in quantitativen 15N-NMR-Spektren unterdrückt werden. Die entwickelte zeitoptimierte Quantifizierungsmethode wurde an zwei Probenserien von festen Säuren getestet; zum einen an Aluminiumhydroxidfluoriden, als Vertreter von Verbindungen mit stark sauren Zentren, und zum anderen an hydroxylierten Magnesiumfluoriden, als Vertreter schwach saurer Verbindungen. Der Vergleich mit anderen quantitativen Methoden zeigte, dass die 15N-Festkörper-NMR-Spektroskopie von adsorbiertem Pyridin hervorragend für die Quantifizierung saurer Zentren geeignet ist und Einblicke in die katalytische Aktivität fester Katalysatoren ermöglicht. / The aim of the present dissertation was to develop a method for the quantification of acidic sites on solid surfaces by 15N solid-state NMR with pyridine as probe molecule. 15N NMR of adsorbed pyridine allows to distinguish different types of acidic sites like Lewis and Brønsted sites. The determination of the kind and concentrations of occurring acidic sites is crucial to understand the catalytic activity of a solid catalyst in a reaction.15N NMR measurements are often time-consuming. Hence, a time-optimized NMR quantification procedure was developed which uses 15N single pulse spectra with short pulse repetition delays. For quantitative analysis of these spectra, occurring signals were corrected according to their T1 relaxation. Furthermore, often strong baseline disturbances are observed in single pulse spectra. For the suppression of these disturbances, the EASY method was developed. The EASY method uses two successive scans to obtain quantitative NMR spectra, in which baseline disturbances are suppressed. The developed time-optimized method for the quantification of acidic sites was applied on two series of samples. One series of aluminum hydroxide fluorides as representatives of catalysts with strong acid sites and one series of hydroxylated magnesium fluorides as representatives of weak acidic catalysts. The comparison with other quantitative methods shows that 15N solid-state NMR of adsorbed pyridine is an excellent method for the quantification of acidic sites, because insights in the catalytic activity of a catalyst can be gained.

Die vorliegende Arbeit befasst sich mit mechanistischen Untersuchungen der fluorolytischen Sol-Gel-Synthese von nano-Magnesiumfluorid, sowie verschiedenen Abwandlungen der bekannten Synthese zur gezielten Veränderung der Eigenschaften der erhaltenen Materialien. Es werden die drei im folgenden beschriebenen Themenbereiche behandelt: Der Verlauf der Fluorolyse von Magnesiummethoxid mit methanolischer HFLösung wird mit der 19F-NMR-Spektroskopie über sechs Monate untersucht. Es wird gezeigt, dass MgF2-Nanopartikel, Agglomerate von gestörten MgF2-Partikeln und nicht umgesetzte, adsorbierte HF-Spezies in den Solen nachweisbar sind. Erstmalig werden MAS-NMR-Experimente an Solen beschrieben. Zusätzlich wird die schrittweise Fluorolyse von MgCl2 mittels NMR-Spektroskopie und XRD untersucht. Es werden drei verschiedene Synthesewege vorgestellt, mit denen eine Veränderung von Partikel- oder Kristallitgrößen erreicht wird. Eine sequentielle Synthese ermöglicht die Vergrößerung der Agglomerate im Sol. Das Erhitzen eines Sols zum Sieden unter Rückflusskühlung führt zu einem geringfügigen Anwachsen der Kristallitgröße. Durch Solvothermal-Synthesen wird eine signifikante Vergrößerung der Kristallite erzielt. Der Einfluss verschiedener Reaktionsparameter wird untersucht. Der Einfluss von MgF2 auf die Kristallisation von amorphem TiO2 wird untersucht. Es wird gezeigt, dass die Sol-Gel-Synthese von TiO2 in Gegenwart eines MgF2-Sols (min. 5 mol%) zur Kristallisation von Rutil-TiO2 bei vergleichsweise niedrigen Temperaturen führt. Verschiedene alternative Synthesen werden vorgestellt, durch die bei vergleichbaren Bedingungen nur Anatas-TiO2 erhalten werden kann. Ein möglicher Mechanismus der Strukturinduktion wird vorgeschlagen. / The present Ph.D. thesis deals with mechanistic investigations of the fluorolytic sol-gel synthesis of nano magnesium fluoride. Furthermore, variations of the well known synthesis are introduced. The aim of these variations is to tailor the properties of the synthesized materials. The thesis covers three main chapters briefly introduced below: The course of the fluorolysis of magnesium methoxide with methanolic HF-solution will be monitored for six months using 19F NMR spectroscopy. The existence of MgF2 nanoparticles and agglomerates of disturbed MgF2 particles will be proven. It is demonstrated that hydrogen fluoride does not react immediately after the addition of HF-solution. For the first time MAS-NMR experiments of sols will be conducted. Furthermore, stepwise fluorolysis of magnesium chloride will be followed by NMR spectroscopy and X-ray diffraction. In this case no intermediates will be detected. Three different synthetic approaches capable of tailoring the crystallite and particle sizes will be presented. Using a sequential synthesis leads to increased size of the agglomerates in the sols. It will be demonstrated that heating and refluxing of a sol increases the crystallite size slightly. Solvothermal synthesis will be the last method leading to significant increase in crystallite sizes. Several synthetic parameters will be varied to identify their influence on the received crystallites. The influence of nano MgF2 on the crystallisation of amorphous TiO2 is investigated. It will be shown, that the sol-gel synthesis of TiO2 in the presence of a MgF2 sol leads to the crystallisation of the rutile polymorph of TiO2. The temperature treatment for that is comparatively low and just 5 mol% MgF2 are necessary. Furthermore, a different alternative synthesis will be introduced, that gives the anatase polymorph at the same conditions. Eventually a possible mechanism for the structural induction is proposed.

Das Hauptaugenmerk dieser Arbeit liegt auf einer Pilotstudie zur Darstellung von Eisen(III)fluorid (FeF3) unter Verwendung von Sol-Gel-Syntheserouten. Eine modifizierte fluorolytische Sol-Gel-Synthese wurde entwickelt um bi-acide auf FeF3 basierende Materialien zu erhalten. Die Synthese erzeugt Hydroxygruppen, die potentiellen Brønsted-sauren Zentren, auf der Oberfläche der klassischen Lewissäure FeF3. Im Anschluss wurde Magnesiumfluorid (MgF2) als Matrix eingesetzt. Verglichen mit FeF3 zeigen ternäre FeF3-MgF2 bemerkenswert hohe Oberflächen und verbesserte Porosität. Das Wichtigste jedoch ist, das hauptsächlich starke Lewis- und mittelstarke Brønsted-saure Zentren auf der FeF3-MgF2 vorhanden sind. Des Weiteren wurden, unter Verwendung anderer Erdalkalimetallfluoride (CaF2 oder SrF2) und Zinkfluorid (ZnF2) als Matrix, Serien ternärer Fluoridmaterialien synthetisiert und systematisch untersucht. Durch Charakterisierung der FeF3-MF2-Oberflächen konnten systematische Veränderungen hinsichtlich Größe der Oberfläche, Porosität und Azidität festgestellt werden. Mit abnehmender Atomnummer (von Sr zu Mg) erhöht sich die Stärke der sauren Zentren, während die mittlere Porengröße dramatisch abnimmt. Darüber hinaus führt ein größeres M-zu-Fe-Verhältnis generell zu kleineren Porengrößen und höheren Oberflächen. Diese Ergebnisse implizieren, dass die Eigenschaften ternärer FeF3-MF2 durch Veränderung der MF2-Matrix oder des M-zu-Fe-Verhältnisses einstellbar sind. Schlussendlich konnte anhand einer Modellreaktion, der Isomerisierung von Citronellal zu Isopulegolen, die katalytische Aktivität der bi-aziden Zentren der auf FeF3 basierenden Materialien nachgewiesen werden. Zusätzlich wurde in dieser Arbeit diskutiert wie Oberfläche, Porosität und Azidität gemeinsam die katalytische Aktivität von FeF3-MgF2 bestimmen. Diese Arbeit beweist damit die Realisierbarkeit der Synthese neuer nanoskopischer Metallfluoride mit gewünschten Oberflächeneigenschaften. / This work serves as a pilot study on the development of iron(III) fluoride (FeF3) based materials with surface bi-acidity. A modified fluorolytic sol-gel route was established to prepare the bi-acidic FeF3-based materials. The synthesis procedure introduced hydroxyls, the potential Brønsted acid sites, on the surface of a classic Lewis acid, FeF3. Subsequently, magnesium fluoride (MgF2) was used as matrix. Comparing with FeF3, the ternary FeF3-MgF2 showed remarkable high surface area and enhanced porosity. Most importantly, strong Lewis and medium strong Brønsted acid sites were found predominant on the FeF3-MgF2 surface. Next a series of ternary fluoride materials were synthesised and studied systematically, using other alkaline earth metal fluorides (CaF2 or SrF2) as well as zinc fluoride (ZnF2) as matrices. Surface characterisation of FeF3-MF2 revealed systematic changes in their surface area, porosity, and surface acidity. With decreasing atom numbers (from Sr to Mg), strengths of surface acidic sites and surface area increased, while the average pore size decreased drastically. Moreover, higher M-to-Fe ratio generally resulted in smaller pore size and larger surface area. These findings imply that the properties of ternary FeF3-MF2 are tunable by changing the MF2 matrix or the M-to-Fe ratio or both. Last but not least, in the model reaction, isomerisation of citronellal to isopulegols, FeF3-based materials were highly active due to their bi-acidity. Finally this work discussed how surface area, porosity, and surface acidity jointly determined the catalytic activity of FeF3-MF2. In conclusion, this work demonstrates the feasibility to synthesise novel nanoscopic metal fluorides with desirable surface properties.

Introdução - A quantidade de flúor ingerida, proveniente de todas as fontes, durante o período crítico de formação dos dentes, é o principal fator de risco para a fluorose dentária. Dentre estas fontes estão a água fluoretada, o dentifrício fluoretado e os alimentos, bebidas, fórmulas e suplementos infantis. Considerando-se que a fluorose dentária tem aumentado em todas as regiões é importante avaliar, além da água e do dentifrício, também a contribuição diária do consumo alimentar das crianças e a concentração de flúor nesses itens alimentares para a ingestão de flúor. Objetivo - Descrever o consumo alimentar de crianças de 2 a 6 anos, com relação ao flúor. Métodos - Foram avaliadas 379 crianças, de 2 a 6 anos, faixa etária de risco para fluorose, residentes em Bauru - São Paulo, município com fluoretação artificial da água de abastecimento público. A amostragem foi estratificada por setor, baseando-se no Plano Diretor do Município. O consumo alimentar foi avaliado pelo Questionário de Freqüência Alimentar Semiquantitativo, aplicado aos pais ou responsáveis, e a concentração de flúor nos itens alimentares a partir de análises laboratoriais. As crianças foram classificadas quanto à ingestão diária de f1úor de acordo com a Dietary Reference Intakes. Resultados - Dentre os 70 itens alimentares, o arroz, a água de abastecimento público e o leite foram os mais consumidos; o chá preto, o leite em pó de soja diluído com água de abastecimento público e o biscoito Danyt\'s® apresentaram maior concentração de flúor; a água de abastecimento público, o refrigerante Coca-Cola® e a batata frita representaram maior contribuição diária para ingestão de flúor. Os itens alimentares mais consumidos apresentaram, em média (±DP), concentração de flúor (0,015 ± 0,028 mgF/porção) significantemente menor (p = 0,03) que os menos consumidos (0,107 ± 0,162 mgF/porção). Os itens alimentares com maior concentração de flúor contribuíram significantemente (p < 0,001) para a ingestão do halogênio (0,018 ± 0,037 mgF/dia). A média da ingestão de flúor por meio dos alimentos sólidos e líquidos, da água e da escovação foi de 0,017 ± 0,016; 0,011 ± 0,004 e 0,036 ± 0,028 mgF/kg peso/dia, respectivamente, totalizando 0,064 ± 0,035 mgF/kg peso/dia. Das 379 crianças, 31,2% apresentaram risco de fluorose. O dentifrício e os itens alimentares (sólidos, água e outros líquidos) contribuíram com 57% e 43%, respectivamente, para a ingestão de flúor. Conclusão - O dentifrício foi a principal fonte para a ingestão de f1úor pelas crianças, porém, a concentração desse halogênio nos itens alimentares contribuiu significantemente para a ingestão, representando risco para f1uorose dentária. / The quantity of fluoride ingested, deriving from all sources, during the critical period of formation of the teeth, is the main factor of risk for the dental fluorosis. Among this sources, we have the fluoridated water, the fluoridated dentifrice and the food, drinks, chemical formula and the infant supplements. Taking into consideration that the dental fluorosis has increased in all regions, it is important to evaluate it, besides the water and the dentifrice, the daily contribution of children\'s food consumption and the concentration of fluoride in these food items for the ingestion of fluoride. Objective - Describe the food consumption of children from 2 to 6 years old, relationg to fluoride. Methods - 379 children were evaluated at risking ages for fluorosis, residents in Bauru - São Paulo, district with artificial f1uoridation. The sampling was stratified by sector, based on the Director\'s Plan of the District. The food intake was evaluated by the Food Frequency Semiquantitative Questionnaire, applied on parents or responsable one, and the concentration of fluoride on the food items from analyses in laboraties. The children were classified based on theis daily ingestion of fluoride according to the Dietary Reference Intakes. Results - Among the 70 food items, rice, public water supply and the milk were the most consumed ones; the black tea, the soybean powdered milk diluted in public water and the biscuit Danyt\'s® presented the gratest daily contribution for the ingestion of fluoride. The most consumed food items present, in average (± DP), concentration of fluoride (0,015 ± 0,028 mg F / portion), significantly lower (p = 0,03) that the less consumed (0,107 ± 0,162 mgF/portion). The food items with the greatest concentration of fluoride contributed significantly (p < 0,001) for the ingestion of the mineral (0,018 ± 0,037 mgF/day). The average amount of fluoride ingestion taken from the solid food and the liquid ones (except water) coming from the water and the teeth brushing was 0,017 ± 0,016; 0,011 ± 0,004 and 0,036 ± 0,028 mgF/kg weight/day, respectively, totalizing 0,064 ± 0,035 mgF/kg weight/dia. 31,2% of the 379 children presented risk of fluorosis. The dentifrice and the food items (solid, water and other liquids) contributed with 57% and 43%, respectively, for the ingestion of fluoride. Conclusion - The dentifrice was the main source for the ingestion of fluoride, by the children, however, the concentration of this mineral in food items contributed significantly for the ingestion by the children, representing risk for dental fluorosis.

L’émergence des souches bactériennes résistantes aux antibiotiques est un phénomène inquiétant, qui se répand à travers le monde. Staphylococcus aureus et Pseudomonas aeruginosa sont des bactéries pathogènes opportunistes multi résistantes qui peuvent causer plusieurs maladies. Cependant, ces bactéries deviennent difficiles à traiter avec des antibiotiques sans occasionner de toxicité. Alors pour trouver des solutions, c’est nécessaire de développer de nouvelles molécules afin de combattre les agents pathogènes résistants. Grâce à leur action pharmacologique, les fluorures exercent un certain effet antibactérien au niveau de l'émail des dents; donc, leur association aux antibiotiques pourrait bien a méliorer l’activité antimicrobienne. De ce fait, nous nous sommes proposés d’étudier les activités in vitro de la vancomycine (VAN), l’oxacilline (OXA), la ceftazidime (CFT) et la méropenème (MER) libre ou associée au fluorure de sodium (NaF) et fluorure de lithium (LiF) qui ont été évaluées sur des souches S.aureus et P.aeruginosa sensibles et résistantes, par la méthode de la microdilution en bouillon, déterminant leur concentration minimale inhibitrice (CMI), leur concentration minimale bactéricide (CMB), leur courbe cinétique (Time-Kill). Leur cytotoxicité sur les globules rouges humains, et leur stabilité à la température de 4°C et 22°C ont été étudiées. Les associations des antimicrobiens aux dérivés des fluorures ont montré une amélioration de l’effet des antibiotiques par la réduction des leurs concentrations et toxicité pour traiter correctement ces pathogènes résistants. Par conséquent, des antibiotiques associés aux dérivés de fluorure pourraient devenir une option de traitement contre des souches résistantes afin de diminuer la toxicité causée par de fortes doses des antibiotiques conventionnels. / The emergence of bacterial strains resistant to antibiotics is a worrying phenomenon, which has spread worldwide. Staphylococcus aureus and Pseudomonas aeruginosa are multi-resistant opportunistic pathogenic bacteria that can cause many diseases. However, they have become difficult to treat with antibiotics without causing toxicity to humans. It is therefore necessary to develop new molecules against resistant pathogens to combat this problem. Due to their pharmacological action, fluorides have an antibacterial effect on tooth enamel which suggests that their combination with antibiotics could improve antimicrobial activity. Thus, we proposed to study in vitro activities of vancomycin (VAN), oxacillin (OXA), ceftazidime (CFT) and meropenem (MER) alone or combined with sodium fluoride (NaF) and lithium fluoride (LiF ) that were evaluated against resistant and susceptible strains of S. aureus and P. aeruginosa by antimicrobial susceptibility testing , in determining their minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and kinetics (Time-Kill). The evaluation of cytotoxicity on human red blood cells, and determination of stability at two different temperatures (4°C, 22°C) were also performed. Associations of antibiotics with fluoride derivatives showed an improvement by increasing the effect of antibiotics with minimal levels necessary to achieve the same result by reducing their toxicity and to properly kill these resistant pathogens. Therefore, antibiotics associated with fluoride derivatives could become a treatment option against resistant strains and at the same time reduce the toxicity caused by high doses of conventional antibiotics.

Fluoride in drinking water can lead to a crippling disease called fluorosis. As there is no cure for fluorosis, prevention is the only means of controlling the disease and research into fluoride remediation is critical. This work begins by providing a new approach to assessing fluoride remediation strategies using a combination of groundwater chemistry, saturation indices, and multivariate statistics based on the results of a large groundwater survey performed in a fluoride-contaminated region of India. From the Indian groundwater study, it was noted that one technique recommended for defluoridation involved using hydrous ferric oxide (HFO) as a solid phase sorbent for fluoride. This prompted investigation of bacteriogenic iron oxides (BIOS), a biogenic form of HFO, as a means of approaching bioremediation of fluoride. Batch sorption experiments at ionic strengths ranging from 0.001 to 0.1 M KNO3 and time course kinetic studies with BIOS and synthetic HFO were conducted to ascertain total sorption capacities (ST), sorption constants (Ks), and orders of reaction (n), as well as forward (kf) and reverse (kr) rate constants. Microcosm titration experiments were also conducted with BIOS and HFO in natural spring water from a groundwater discharge zone to evaluate fluoride sorption under field conditions. This thesis contributes significant, new information regarding the interaction between fluoride and BIOS, advancing knowledge of fluoride remediation and covering new ground in the uncharted field of fluoride bioremediation.

Η κρυστάλλωση και η διάλυση αλάτων αποτελούν σημαντικές διεργασίες οι οποίες συνεισφέρουν στην φθορά των μνημείων της πολιτιστικής μας κληρονομιάς, τα οποία έχουν κατά κύριο λόγο κατασκευασθεί από δομικά υλικά όπως ο ασβεστόλιθoς και το μάρμαρο. Η κρυστάλλωση ευδιάλυτων αλάτων (π.χ. θειϊκό νάτριο, θειϊκό μαγνήσιο, χλωριούχο νάτριο) σε πορώδη υλικά έχει καταστροφικές επιπτώσεις τόσο στις ιστορικές όσο και στις σύγχρονες κατασκευές από σκυρόδεμα. Το πιο κατεστρεπτικό άλας για την ακεραιότητα των κατασκευών έχει αποδειχθεί, ότι είναι το θειίκό νάτριο. Η κατανόηση του μηχανισμού κρυστάλλωσης του άλατος αυτού είναι απαραίτητη προϋπόθεση για τον περιορισμό ή τον έλεγχο του σχηματισμού του σε ατμοσφαιρικές συνθήκες. Για τον σκοπό αυτό, έγινε συστηματική μελέτη της κρυσταλλικής ανάπτυξης του δεκαένυδρου θειϊκού νατρίου (Μιραμπιλίτης) σε υπέρκορα διαλύματά του. Αναπτύχθηκε μεθοδολογία βασισμένη στον εξώθερμο χαρακτήρα της κρυσταλλικής ανάπτυξης του μιραμπιλίτη. Η πειραματική μελέτη περιορίσθηκε στην ετερογενή κρυσταλλική ανάπτυξη τόσο σε φύτρα Μιραμπιλίτη, όσο και σε ξένα υποστρώματα. Τα υποστρώματα τα οποία μελετήθηκαν περιλάμβαναν ασβεστόλιθο από την Γρανάδα (ασβεστιτικός κυρίως) καθώς και ψαμμόλιθο (Πράγα, Τσεχίας) πυριτικής κατά κύριο λόγο σύστασης. Η μελέτη της κινητικής της κρυσταλλικής ανάπτυξης του Μιραμπιλίτη, έδειξε ότι το καθορίζον την ταχύτητα στάδιο είναι η διάχυση των δομικών μονάδων στην επιφάνεια των κρυσταλλικών φύτρων του Μιραμπιλίτη. Το συμπέρασμα αυτό οδήγησε στην δοκιμή οργανοφωσφορικών ενώσεων, ως προς την επίδρασή τους στην κινητική της κρυσταλλικής ανάπτυξης του μιραμπιλίτη. Οι ενώσεις αυτές ιονίζονται και αλληλεπιδρούν αποτελεσματικά με την κρυσταλλική επιφάνεια δηλητηριάζοντας τα ενεργά κέντρα κρυστάλλωσης. Ο βαθμός ιονισμού βρέθηκε ότι είναι καθοριστικός για την ανασταλτική τους δράση. Πειράματα ταχείας καταβύθισης ευδιάλυτων αλάτων ηλεκτρολυτών σε ασβεστολιθικά και ψαμμιτικά δοκίμια τα οποία έγιναν τόσο με εμβάπτιση, όσο και με έκθεση σε θάλαμο αλατονέφωσης επιβεβαίωσαν τα αποτελέσματα της μελέτης της κινητικής της κρυστάλλωσης του Μιραμπιλίτη και της σχετικής αποτελεσματικότητος των αναστολέων που χρησιμοποιήθηκαν. Πλην της κρυσταλλικής ανάπτυξης ευδιάλυτων αλάτων, σημαντική συνεισφορά στην αποδόμηση των δομικών υλικών παίζει και η διάλυση του ανθρακικού ασβεστίου, το οποίο και αποτελεί τη βασική συστατική τους ένωση. Για τη μελέτη της διεργασίας της κρυσταλλικής ανάπτυξης και διάλυσης του ανθρακικού ασβεστίου τόσο απουσία όσο και παρουσία ανιόντων όπως τα θειϊκά και τα ανιόντα φθορίου χρησιμοποιήθηκε η μικροσκοπία ατομικής δύναμης,η οποία έδωσε την δυνατότητα in situ μέτρησης του ρυθμού κρυσταλλικής ανάπτυξης και διάλυσης σε συνθήκες σταθερού κορεσμού. Η παρουσία θειϊκών ανιόντων έδειξε ότι η κρυσταλλική ανάπτυξη του ανθρακικού ασβεστίου αναστέλλεται ενώ η παρουσία φθορίου επιταχύνει τη διάλυση. Τα αποτελέσματα των μετρήσεων της κινητικής των διεργασιών έδειξαν ότι οι επιμολύνσεις στα υπέρκορα διαλύματα δρούν στην κινητική λόγω προσρόφησης και δέσμευσης των ενεργών κέντρων κρυσταλλικής ανάπτυξης διάλυσης. / The research made in the present PhD Thesis entitled “Crystallization and dissolution study of electrolyte salts”. The objective of the dissertation concerned both crystallization and dissolution processes of soluble sodium sulfate and insoluble calcium carbonate electrolyte salts approached by different experimental aspects but directly connected to environmental and scientific issues. Salt crystallization is an important cause for the weathering and damage of historical and cultural heritage artifacts and ornamental stones. Soluble salts (i.e. sodium sulfate, magnesium sulfate, sodium chloride) have also a damaging and fateful impact on civil engineering structures of roads and building foundations. Most damaging salt for such built frameworks is proven to be sodium sulfate salt. Only when we have a better understanding of sodium sulfate crystallization in an unconstrained fluid medium can we progress to a study of sodium sulfate crystallization in porous building materials. At the beginning of this study batch crystallization experiments of sodium sulfate salt were conducted. Additionally potential organic inhibitors (i.e. organophosphonate, polyacrylates) were tested in the same batch experimental system. Popular and applicable limestone building material is of uniform composition consisting mainly calcium (calcitic material). Granada’s calcarenite has been selected as one of the target material to study. This natural stone is representative of the building material utilized in construction material monuments and susceptible to salt crystallization. In situ AFM experiments of both calcite crystal growth and dissolution were performed in the presence of different electrolyte solutions (i.e. sodium sulfate and sodium fluoride). Nanoscale phenomena during the growth of solid solutions on calcite surfaces were performed in the presence of sodium sulfate electrolyte solutions. Further molecular-scale surface processes during both growth and dissolution of calcite in the presence of sodium fluoride electrolyte solutions were carried out. In all cases significant kinetic data and reaction mechanisms were extracted. Accelerated degradation of Granada’s limestone and Czech sandstone experiments were executed. Tested materials were exposed and impregnated in concentrated solutions of soluble salts (i.e. sodium sulfate, magnesium sulfate and sodium chloride). Immersed limestone type material showed susceptibility to sodium sulfate and sandstone type material to sodium chloride salt solution. Different pre-treatments of limestone specimens with organophosphonate compounds resulted in limiting material damage from sodium sulfate influence. The use of such organic compounds may direct towards a potential implication of conserving building frameworks. Finally suspended limestone rods were subjected to sodium sulfate spray chamber. Pre-treatment of limestone rods with organophosphonate compounds were completed. Again applications of organophosphonate compounds to exposure of limestone material in salt spray chamber may work towards a case of preventing porous material from salt damage and protect building stones.

CNPq, Capes e FINEP / Este trabalho descreve a produção e caracterização de guias de onda óticos em cristal de fluoreto de lítio (LiF) produzidos expondo o cristal a um feixe focalizado de um laser de femtosegundo, com o deslocamento do cristal na direção perpendicular ao eixo de propagação do feixe. A medida da emissão, sob iluminação específica, demonstra a presença de centros de cor dos tipos F2 e F3+ nas regiões do cristal expostas ao feixe focalizado do laser. As estruturas produzidas possuem incremento do índice de refração em relação ao índice de refração do cristal. Tais estruturas são caracterizadas em termos da sua morfologia usando microscopia convencional e confocal. A capacidade de guiamento de luz é investigada acoplando fontes laser com diferentes comprimentos de ondas. Os modos suportados são também analisados, bem como as perdas na propagação. A produção de guias de ondas de Bragg é testada acoplando uma fonte de luz branca e comparando seu espectro com o espectro que passa somente pelo cristal. A capacidade de guiamento das estruturas produzidas é confirmada pela análise dos perfis de campo próximo. Os guias suportam poucos modos e os incrementos de índices obtidos são da ordem de 10^-4. / This work describes the production and characterization of optical waveguides in lithium fluoride crystal (LiF) produced by exposing the crystal to a focused femtosecond laser beam, with the crystal displacement perpendicular to the beam. The measured emissions, with specific illumination, demonstrate the presence of color centers of types F2 and F+3 at the crystal regions exposed to the focused laser beam. The produced structures have increased refractive index relative to the crystal refraction index. Such structures are characterized in terms of their morphology using conventional and confocal microscopy. Their ability to guide light is investigated through coupling different laser light. The propagation modes supported by the guides are also estimated, as well as the propagation losses. The production of a Bragg grating waveguide is locked for by coupling a white light in the guides and comparing its spectrum with that passing only through the crystal. The guiding capacity of the structural changes produced is confirmed by the near-field profile analysis. The guides support few propagation modes and the obtained changes in the refractive index are in the order of 10^-4.

Rare-earth ions co-doped lanthanum fluoride (LaF3) nanoparticles (NPs) were synthesized and the effect of different annealing temperatures investigated. We have also investigated the thermo-optical properties of Tm3+ and Eu3+ doped Y2O3 transparent ceramics. The LaF3:Yb3+/Ho3+ and LaF3:Yb3+/Tm3+ NPs were treated thermally by 3 hs at 300, 500, 700, and 900 °C and then characterized with respect to crystalline structures, sizes, shapes, presence of other crystalline phases and luminescent properties. From the experimental results, optimization of optical and structural properties were obtained for the thermal treatment at 500 °C while maintaining the LaF3 crystalline phase. However, it was observed the formation of lanthanum oxifluoride (LaOF) under thermal annealing at 900 °C, with higher luminescence in the near infrared, which makes this host to deserve further study. It was also synthesized LaF3 NPs varying the Tm3+ and Ho3+ ions concentrations with fixed Yb3+ one and these samples were thermally treated at 500 and 900 °C by 3 hs. The 1.2, 1.47, 1.8, and 2 μm emissions behaviors of Tm3+ and Ho3+ ions were investigated, in order to obtain the best concentrations for these emissions in these two hosts: LaF3 and LaOF. We also synthesized Yb3+/Tm3+ and Yb3+/Ho3+ co-doped LaF3 using nitrate and chloride precursors and these samples were annealed at 500 and 900° C to observe what occurs in the structural, morphological, and optical properties of the LaF3 and LaOF. As a result, no significant difference was observed in their structural and optical properties, thus facilitating the use of nitrate and chloride precursors for further researches using these hosts. Another very interesting and promising material is the yttrium oxide (Y2O3) transparent ceramics. In this case, we investigated using the thermal lens technique, conventional spectroscopy of luminescence and temporal dynamic, the thermal and optical properties of Y2O3:Tm3+ and Y2O3:Eu3+. The thermal properties obtained were: thermal diffusivity =26.06x10-3cm2/s, thermal conductivity =5.8 W/m.K, and the temperature coefficient of the optical path length change ⁄=2.978x10-6K-1. Small values for D and k were obtained in comparison to those of the literature, and this was attributed to the grain size of the investigated ceramics. The luminescence decays along with the thermal lens spectroscopy results were complementary to a complete characterization of the Y2O3:Tm3+ ceramics, enabling obtaining the fluorescence quantum efficiency of the Tm3+ 3F4 level emitting at 1.8 μm, which was estimated at η1=0.84. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nanopartículas (NPs) de fluoreto de lantânio (LaF3) codopadas com íons terras-rara foram sintetizadas e avaliado o efeito de tratamento térmico em diferentes temperaturas. Também investigamos as propriedades termo-ópticas de cerâmicas transparentes de Y2O3 dopadas com os íons Tm3+ e Eu3+. As NPs de LaF3:Yb3+/Ho3+ e LaF3:Yb3+/Tm3+ foram tratadas termicamente por 3 horas nas temperaturas de 300, 500, 700 e 900 °C para então caracterizá-las com relação as suas estruturas cristalinas, tamanhos, formas, presença de outras fases cristalinas e propriedades luminescentes. A partir de resultados experimentais, verificou-se a otimização das propriedades estrutural e óptica no tratamento térmico de 500 °C, mantendo a fase cristalina de LaF3. No entanto, foi observada à formação de óxifluoreto de lantânio (LaOF) no tratamento térmico a 900 °C, resultando em maior luminescência no infravermelho próximo, o que faz essa matriz merecer um estudo mais aprofundado. Também, foram sintetizadas NPs de LaF3, mudando a concentração dos dopantes Tm3+ e Ho3+, mantendo fixa a de Yb3+, e essas amostras foram tratadas termicamente a 500 e 900 °C por 3 horas. Foram investigados os comportamentos das emissões em 1,2; 1,47; 1,8 e 2 μm dos íons Tm3+ e Ho3+, com intuito de se obter as melhores concentrações para essas emissões nessas duas matrizes: LaF3 e LaOF. Sintetizamos também LaF3 codopadas com Yb3+/Tm3+ e Yb3+/Ho3+, usando precursores nitratos e cloretos e as tratamos termicamente a 500 e 900 °C para se observar o que ocorre nas propriedades estruturais, morfológicas e ópticas nas matrizes LaF3 e LaOF. Como resultado, não foram observadas diferenças significativas em suas propriedades estruturais e ópticas, facilitando assim o uso de precursores nitratos e cloretos para futuras pesquisas usando essas matrizes. Outra matriz promissora é a cerâmica transparente de óxido de ítrio (Y2O3). Neste caso, investigamos usando a técnica de lente térmica e espectroscopia convencional de luminescência e dinâmica temporal, as propriedades térmicas e ópticas de Y2O3:Tm3+ e Y2O3:Eu3+. As propriedades termo-ópticas obtidas foram: difusividade térmica =26,06×10-3 cm2/s, condutividade térmica =5,8 W/m.K e o coeficiente de variação do caminho óptico com a temperatura ⁄=2,978×10-6 K-1. Valores pequenos para D e foram obtidos, quando comparados com os da literatura. Tais valores foram atribuídos ao tamanho dos grãos das nossas cerâmicas. Os decaimentos das luminescências, juntamente com os resultados da espectroscopia de lente térmica, foram complementares para uma caracterização completa da cerâmica de Y2O3:Tm3+, possibilitando a obtenção da eficiência quântica de fluorescência do nível 34 do íon Tm3+ emitindo em 1,8 μm, a qual foi estimada em 1=0,84.