京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22452号 / 工博第4713号 / 新制||工||1736(附属図書館) / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 田中 勝久, 教授 三浦 清貴, 教授 藤田 晃司 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

L’uranium (U) et le fluor (F) sont des substances néphrotoxiques naturelles et anthropogéniques auxquelles la population peut être exposée quotidiennement. Cependant, leurs effets à faibles doses restent méconnus et des études précédentes suggèrent qu’une exposition chronique à de faibles doses pourrait induire une réponse adaptative (RA). Afin de mettre en évidence cette RA rénale in vivo, un protocole d’exposition prime à faibles doses suivie d’un traitement challenge néphrotoxique a été mis en place. Une première étude dose-réponse aiguë a permis de définir nos conditions challenge, avec des doses néphrotoxiques de 5 et 7.5 mg/kg d’U et de F, et un temps d’analyse de 72h post-injection. Pour l’étude de la RA, les souris ont été contaminées 6 mois via l’eau de boisson à des doses prime d’U (0, 10, 20 et 40 mg/L) ou de F (0, 15, 30 et 50 mg/L), puis traitées aux concentrations « challenge ». Une RA est observée aux doses respectives de 20 et 50 mg/L d’U et de F, avec un retour à la normale de l’expression et de la sécrétion de biomarqueurs de néphrotoxicité KIM-1 et CLU en comparaison aux animaux non pré-exposés. Une diminution de l’apoptose ou de l’expression in situ de VCAM est observée chez les animaux pré-exposés respectivement à 20 mg/L d’U ou à 50 mg/L de fluor, concentrations auxquelles la RA a été identifiée. L’autophagie, la réponse UPR et le recrutement de cellules inflammatoires sont des mécanismes induits par l’U alors que seule la réponse UPR est induite par le F. Cependant, nos résultats ne permettent pas de les identifier comme des mécanismes impliqués dans la RA, car ces derniers sont induits avec ou sans préexposition. En conclusion, cette étude montre l’existence d’une RA dans le cadre d’une exposition chronique à de faibles doses d’U ou de F chez la souris, avec l’induction de mécanismes adaptatifs tels que la régulation de l’apoptose et de l’inflammation. Ces résultats permettent de mieux appréhender les effets de faibles expositions chroniques chez l’Homme, et d’apporter de nouvelles connaissances pour la radioprotection de l’Homme. / Human population can be daily exposed to uranium (U) and fluoride (F) because of their natural and anthropogenic presence in the environment. Although U and F are known to be nephrotoxicant at high doses, their effects after low dose exposures are still unknown and previous studies suggested that chronic exposures to low doses of U or F could induce adaptive responses (AR). Therefore, a mouse in vivo study was designed and carried out to examine whether exposure to chronic low priming doses of U and F can induce AR in the kidney upon exposure to nephrotoxic challenge treatment. A pilot dose-response study allowed selecting the nephrotoxic challenge treatments (5 mg/kg U and 7.5 mg/kg F), with a time of analysis of 72h post treatment. To study the AR, mice were exposed through drinking water for 6 months to priming doses of U (10, 20 and 40 mg/L) or F (15, 30 and 50 mg/L), and subsequently challenged. An AR was observed at the doses of 20 mg/L U and 50 mg/L F, with a return to normal gene expression and urinary levels of nephrotoxicity biomarkers KIM 1 and CLU in comparison with the non-pre-exposed mice. Apoptosis was reduced in animals pre-exposed to 20 mg/L U and a decrease of VCAM in situ expression was observed in animals pre-exposed to 50 mg/L F. These concentrations correspond to the appearance of AR. The unfolded protein response (UPR), autophagy and inflammatory cell recruitment were the mechanisms induced by U whereas only UPR was induced by F. However, these mechanisms were induced in challenged animals irrespective of pre-exposure. Thus, our results do not allow us to identify these mechanisms as those involved in the AR. In summary, our data showed the existence of an AR to low doses of U and F delivered chronically to mice, with the induction of adaptive mechanisms such as apoptosis and inflammatory regulation. Results of this study allow for better understanding of the potential effects chronic low-dose exposures of U and F on human population, and provide new knowledge for informing the radioprotection system.

The most appropriate and widely used source of drinking water for the rural populations of South Africa is groundwater. Pilot studies and surveys conducted by the Department of Water Affairs and Forestry (DW AF) indicated that there are a number of boreholes across the country that contain apart from fluoride, levels of nitrate, some heavy metals, total dissolved solids, sulphates and faecal coliform (in isolated regions) that could pose a health risk if the water is used for drinking purposes. Very few boreholes have been tested for heavy metals or toxic organic substances. However considering the levels of fluoride, in general, groundwater is of acceptable quality except for some provinces in which elevated levels of natural groundwater fluoride occurs. Very high levels of fluoride, >4 mg/l occur in some groundwater sources in all nine provinces of South Africa, especially in the Limpopo, North-West, Eastern Cape, Northern Cape, Western Cape and KwaZulu Natal provinces. A superficial inspection reveals that most of the local people in those areas suffer from dental fluorosis at varying degrees. The main aim of this study is to determine the distribution of the fluoride ion concentration levels in South African groundwater and the impacts thereof on dental health. The available data is used to assess the distribution of the various fluoride ion concentration levels in some national groundwater sources. Areas of particularly high or low fluoride levels are identified. Results from an epidemiological survey carried out by the National Department of Health (NDOH) are used concurrently with the fluoride data to determine the percentage morbidity of dental fluorosis in each area The results are compared in order to determine if any relationship exists between the occurrence of fluoride in drinking water and the incidences of dental fluorosis. Vegter's lithostratigraphy and the simplified geology of South Africa are used to interpret the results and assess the role of surface geology in the release and distribution of fluorides in groundwater. The role of other factors such as climate and the interactions of the fluoride ion and other water quality parameters in aqueous media are also assessed. / Dissertation (MSc (Water Utilization))--University of Pretoria, 2006. / Chemical Engineering / unrestricted

Depuis les années 1970, le développement des sources lasers de puissance fonctionnant autour de 2 µm basées sur des cristaux dopés Thulium Tm3+ et/ou Holmium Ho3+est un domaine de recherche actif du fait de ses multiples applications. L’émission autour de 1.9 µm correspond à une transition du niveau excité 3F4 vers le niveau fondamental 3H6 dans un ion trivalent Tm3+, alors que l’émission à 2 µm et au-delà correspond à la transition entre le niveau 5I7 et le niveau fondamental 5I8 de l’ion Ho3+. Ces transitions laser font aujourd’hui l’objet de nombreuses applications dans domaines très variés. nous avons étudié les propriétés spectroscopiques de cristaux de fluorures dopés terres rares en vue d’une émission autour de 2 µm. À partir des spectres d’absorption obtenus, l’analyse de Judd-Ofelt a permis de calculer les durées de vie radiatives ainsi que les rapports de branchement dans les ions Tm3+ et Ho3+. En comparaison avec d’autres cristaux tels que les oxydes, les durées de vie des niveau 3F4(Tm3+) et 5I7(Ho3+) dans les cristaux de fluorures sont plus longues ce qui favorise un fonctionnement laser en régime impulsionnel. Une étude sur la dynamique de fluorescence a été réalisée afin de caractériser l’émission autour de 1.9µm de l’ion Tm3+ et celle autour de 2µm de l’ion Ho3+. Les spectres d’émission obtenus offrent de larges bandes, assez structurées dans la matrice LiYF4 et plus larges et moins structurées dans la matrice CaF2. Dans un second temps, en mesurant les durées de vie du niveau émetteur 3F4 pour différentes concentrations en ions Tm3+, nous avons calculé les paramètres de transferts. Les résultats obtenus ont montré que le processus de relaxation croisée est beaucoup plus efficace dans le cristal CaF2 que dans le LiYF4. Nous avons calculé également les coefficients de transfert et de transfert inverse entre les ions Tm3+ et Ho3+ suite à une excitation de l’ion Tm3+. Nous avons montré que la matrice LiYF4 offre une meilleure efficacité de transfert en vue d’une émission autour de 2µm. Le fonctionnement laser de couches minces en configuration « disque mince » a été étudié. Une première démonstration d’un laser en disque mince LiYF4 : Tm émettant à 1.9 µm réalisé à partir d’une couche épitaxiée par LPE a été faite. En simple passge, une puissance de sortie de 306 mW et une efficacité laser de 36% en puissance absorbée sont atteintes pour une couche de 240 μm d'épaisseur.nous avons étudié un oscillateur laser en guide d’onde LiYF4 :Tm en géométrie planaire et linéaire. Ces guides sont caractérisés par de faibles pertes de propagation grâce à la qualité du procédé de fabrication. Une puissance maximale de 470 mW et un rendement de 14% en puissance incidente ont été obtenus. Une modélisation numérique de l’amplification optique montre que le guidage des faisceaux pompe et sonde permet d’atteindre des gains importants. Le modèle est ensuite adapté pour le régime de saturation afin de calculer le rendement d’extraction et de déterminer le potentiel des guides LiYF4 :Tm3+ en tant comme amplificateur autour de 1.9 µm / Since the 1970s, the development of power laser sources operating around 2 μm based on Thulium Tm3 + and / or Holmium Ho3 + doped crystals is an active field of research because of its multiple applications. The emission around 1.9 μm corresponds to a transition from the excited level 3F4 to the fundamental level 3H6 in a trivalent ion Tm3 +, whereas the emission at 2 μm and beyond corresponds to the transition between the level 5I7 and the fundamental level 5I8 of the Ho3 + ion. These laser transitions are today the subject of many applications in a wide variety of fields. We have studied the spectroscopic properties of rare earth doped fluoride crystals for emission around 2 μm. From the absorption spectra obtained, the Judd-Ofelt analysis made it possible to calculate the radiative lifetimes as well as the branching ratios in the Tm3 + and Ho3 + ions. In comparison with other crystals such as oxides, the lifetimes of the 3F4 (Tm3 +) and 5I7 (Ho3 +) levels in the fluoride crystals are longer, which favors pulse-mode laser operation. A study on fluorescence dynamics was carried out in order to characterize the emission around 1.9 μm of the Tm3 + ion and that around 2 μm of the Ho3 + ion. The emission spectra obtained have broad bands, fairly structured in the LiYF4 matrix and wider and less structured in the CaF2 matrix. In a second step, by measuring the lifetimes of the 3F4 emitter level for different Tm3 + ion concentrations, we calculated the transfer parameters. The results obtained showed that the process of cross relaxation is much more efficient in the CaF2 crystal than in LiYF4. We also calculated the transfer and inverse transfer coefficients between Tm3 + and Ho3 + ions following excitation of the Tm3 + ion. We have shown that the LiYF4 matrix offers a better transfer efficiency with a view to emission around 2 μm. The laser operation of thin layers in "thin disc" configuration has been studied. A first demonstration of a thin-film LiYF4: Tm laser emitting at 1.9 μm made from an epitaxial layer with LPE was made. In single passge, an output power of 306 mW and a laser efficiency of 36% in absorbed power are reached for a 240 μm thick layer. We have studied a laser oscillator in LiYF4: Tm waveguide in planar geometry. and linear. These guides are characterized by low propagation losses thanks to the quality of the manufacturing process. A maximum power of 470 mW and a yield of 14% in incident power were obtained. A numerical modeling of the optical amplification shows that the guidance of the pump and probe beams makes it possible to achieve significant gains. The model is then adapted for the saturation regime in order to calculate the extraction efficiency and to determine the potential of the LiYF4: Tm3 + guides as an amplifier around 1.9 μm

Magister Theologiae - MTh / This study aimed to determine the association between dimensional change and surface roughness (Ra) of Vitremer, Activa and Cention N after immersing them into two different media: acidic and artificial saliva media for the period of a year. Measurements were made at 10 time intervals during the observation period.

Les travaux présentés dans ce manuscrit sont consacrés à l’étude de la spectroscopie FTIR à très haute résolution de la molécule de fluorure de sulfuryle SO2F2 qui est apparu récemment comme un polluant atmosphérique important. Une très bonne modélisation de son spectre d’absorption est donc essentielle pour les mesures de concentration atmosphérique.Ce manuscrit comporte cinq parties. La première partie de ce travail de thèse concerne les propriétés de la molécule du fluorure de sulfuryle. La deuxième partie décrit le modèle théorique (formalisme tensoriel, Hamiltonien et moment dipolaire effectifs) que nous avons utilisé pour effectuer les analyses. La troisième partie expose les conditions expérimentales des différents spectres que nous avons enregistré à la ligne AILES du synchrotron SOLEIL à Saint-Aubin (Paris). La quatrième partie décrit le logiciel C2vTDS et enfin dans la cinquième partie, nous présentons les résultats des différentes analyses.Cette thèse a été effectuée au sein du Groupe de Spectrométrie Moléculaire et Atmosphérique (GSMA) de l’Université de Reims Champagne-Ardenne et au Laboratoire Dynamique Moléculaire et Matériaux Photoniques (LDMMP) à l’Ecole Nationale Supérieure d’Ingénieurs de l’Université de Tunis. / The work presented in this manuscript is devoted to the study of very high resolution FTIR spectroscopy of the molecule of sulfuryl fluoride, SO2F2, which recently appeared as an important atmospheric pollutant. However, a very good modeling of its absorption spectrum is essential for atmospheric concentration measurements.This manuscript has five parts. The first part deals with the properties of the molecule of sulfuryl fluoride. The second part describes the theoretical model (tensor formalism and effective Hamiltonian and dipole moment) that we used to perform the analyzes. The third part presents the experimental conditions of the different spectra that we recorded at the AILES line of the SOLEIL synchrotron at Saint-Aubin (Paris). The fourth part describes the software C2vTDS and finally in the fifth part we present the results of the different analyzes.This thesis was performed in the Molecular and Atmospheric Spectrometry Group (GSMA) of the University of Reims Champagne-Ardenne and the Laboratory of Molecular Dynamics and Photonic Materials (LDMMP - ENSIT) of the University of Tunis.

No description available.

More than two million people in the Chaco-Pampean plain in central Argentina are affected by high As levels in groundwater. The concentrations of As are far exceeding the WHO standard limit for safe drinking water of 0.1 μg/L and the provisional Argentinean limit of 0.5 μg/L. The NE of La Pampa province is one of the areas affected with geogenic As in shallow aquifers within the Chaco-Pampean plain. These aquifers are in closed basins and they are only available water resource of the region for drinking and agriculture purposes. The Pampean aquifer is composed of a multi-layered system of Quaternary loess deposits covered by aeolian sands and also containing layers of rhyolitic volcanic ash, which is considered the primary source of As. Volcanic ash layers can be visible in the shallow sediments or intermixed in the loess. During the weathering of volcanic ash sediments As is dissolved to the aqueous phase and can be quickly adsorbed or co-precipitated on secondary Fe, Al and Mn oxy-hydroxides under favourable conditions. Also, previous more arid climatic conditions have led to the formation of carbonate "calcrete" layers in the top sequences of the loess and this has affected the geochemistry of the aquifer. Two sites were investigated in the NE of La Pampa province in order to assess (i) the quality of groundwater for drinking water use, (ii) the distribution of As and other trace elements in shallow aquifers and (iii) to understand better the factors controlling its mobility in groundwater. The results showed that groundwater was circum-neutral to alkaline and under moderate oxidizing conditions. The predominant groundwater composition was of Na-HCO3 for fresh water and Na-Cl-SO42- for brackish water types. High salinity levels are evidenced by the high Electrical Conductivity and might be explained by to the high evaporation rates. Groundwater sampled in both areas was enriched with As, F and other trace elements at different ranges of concentration. From the total As concentrations, arsenate As(V) predominated over arsenite As(III) species. Shallow groundwater is also enriched with fluoride exceeding the WHO standard limit of 1.5 mg/L and placed in the same As hotspots. One possible factor controlling the mobility of As is the high pH of groundwater, which is controlled by the carbonates equilibrium. Under this high pH conditions As is less strongly bind to Fe, Al and Mn oxy-hydroxides and can be easily mobilized to groundwater when other competing ions are getting adsorbed on the surface sites of binding minerals.

Poly (2-ethyl-2-oxazoline)-based amphiphilic diblock copolymer has the potential to form promising membrane materials for water purification due to the thermal stability and good solubility in aqueous solution and also for gas separation because of the presence of polar amide group along the polymer backbone. Moreover, their self-assembly into micelles renders them candidate materials as nanocarriers for drug delivery applications. In this study, a novel well-defined linear PEtOx-based amphiphilic diblock copolymer with a hydrophobic fluoropolymer, i.e., PVDF, have been successfully synthesized by implementing a synthesis methodology that involves the following four steps. In the first step, poly (2-ethyl-2-oxazoline) (PEtOx) was synthesized via living cationic ring-opening polymerization (LCROP) of 2-ethyl-2-oxazoline (EtOx) monomer. The “living” nature of LCROP allows the desirable termination to occur by using the proper termination agent, namely, water, to achieve the polymer with a terminal hydroxyl group, i.e., PEtOx-OH. The hydroxyl end group in PEtOx-OH was converted to PEtOx-Br using 2-bromopropionyl bromide via an esterification reaction. In the third step, the PEtOx-Br macro-CTA was subsequently reacted with potassium ethyl xanthate to insert the necessary RAFT agent via nucleophilic substitution reaction to obtain PEtOx-Xanthate. It s worth mentioning that this step is vital for the sequential addition of the second block via the RAFT polymerization reaction of fluorinated monomer, i.e., VDF, to finally obtain the well-defined amphiphilic diblock copolymer with variable controlled chain lengths. Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR) and Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the structure of the macroinitiator and final copolymer, respectively. Size Exclusion Chromatography (SEC) determined the number-average molecular weight (Mn) and the polydispersity index (PDI) of the obtained copolymer. Furthermore, the polymorphism of the diblock copolymer characterized by X-Ray Diffraction (XRD) indicated that the copolymer displays the electroactive α-phase. The resultant amphiphilic diblock copolymer exhibits spherical micelles morphology, as confirmed by Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM). Moreover, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) investigated the thermal decomposition behavior of the copolymer and determined the glass transition temperature (Tg ≈ 70 °C), melting temperature (Tm ≈ 160-170 °C), and crystallization temperature (Tc ≈ 135-143 °C) of the diblock copolymer, respectively.

During the past decade, lanthanide doped alkali metal rare earth fluorides have been intensively studied due to their unique properties. Also, nanoparticles of these materials have gained much importance because NaYF4, NaGdF4, NaLuF4 and LiYF4 nanocrystals doped with Yb/Er or Yb/Tm display efficient upconversion emission. The synthesis of NaREF4 nanocrystals (RE = rare earths) has therefore attracted many researchers worldwide. While a large number of procedures is already available for the synthesis of NaREF4 particles of the heavier rare earth ions and for NaYF4, only a very limited number of methods exists for nanocrystals of the lighter rare earth ions, RE = La, Ce, Pr and Nd. In this work, a synthesis method was therefore developed to produce monodisperse sub-10 nm sodium rare earth fluoride nanocrystals of the lighter rare earths, NaREF4 (RE = La, Ce, Pr and Nd) from single-source precursors. Based on this method, the Ostwald ripening, the size focusing and the stability of these nanocrystals were studied; also, the versatility of the method was demonstrated by developing doped nanocrystals of these particles. The procedures developed in this thesis not only allow to prepare the hexagonal β-phase of these materials but also the meta-stable cubic α-phase. The latter is found to be very sensitive to decomposition. This decomposition affects also the synthesis of NaREF4 particles of the hexagonal β-phase where particles of the cubic α-phase form an intermediate product. This thesis also shows that highly sodium deficient α-NaYF4 nanocrystals with a size of less than 10 nm can be prepared which contain much less sodium than the bulk material. These nanocrystals were used as precursor to produce monodisperse sub-10 nm lithium rare earth fluoride (LiREF4, RE = Y, Gd, Lu) nanocrystals. Using this new approach also LiYF4:Yb,Er/LiYF4 core/shell upconversion nanocrystals were prepared, displaying a 35 times enhancement in luminescence intensity compared to the corresponding core particles. Further, this approach provided new insights on intermediate phases formed during the synthesis. Our studies confirmed, for instance, that LiREF4 nanocrystals were formed through an ‘available intermediate phase’, that is, a phase having a composition which is determined by the available cations in the reaction mixture.