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Les actinides sont des radioéléments couramment manipulés par les travailleurs de l'industrie nucléaire et font partie de la menace NRBC (nucléaire, radiologique, biologique, chimique). La contamination cutanée représente une voie d'exposition majeure de ces agents radiologiques. La décontamination de la peau est donc cruciale pour empêcher une dispersion de la contamination et l'absorption systémique du contaminant par la peau. Ce travail s'est attaché à évaluer les profils de pénétration cutanée de deux actinides : l'américium et le plutonium, sous différentes formes, dans un modèle d'étude ex vivo, la peau d'oreille de porc. L'efficacité de décontamination de différents produits usuels a également été testée sur ce modèle, mais aussi sur un modèle in vitro de poudre de couche cornée bovine. Pour compléter l'étude de la décontamination, l'efficacité d'une formulation d'hydrogel de DTPA a également été testée. La détermination de la distribution de la contamination dans la peau a été réalisée à l'aide de différentes techniques d'imagerie : l'autoradiographie par émulsion, le TASTRAK ou encore l'iQID camera. Les résultats ont montré une grande différence dans les profils de pénétration et de rétention des actinides lorsqu'ils sont en solution aqueuse modérément soluble ou en solution organique dans un mélange de solvant. De plus, cette dernière forme modifie fortement la structure cutanée, menant à une forte augmentation de la pénétration cutanée. Les résultats des protocoles de décontamination montrent une efficacité égale du savon (Trait rouge®) comparé au DTPA, qui est le traitement décorporant utilisé également en décontamination. La formulation en hydrogel présente une efficacité supérieure pour le traitement de solutions organiques et met en évidence l'intérêt de développer d'autres formulations galéniques / Actinides are alpha-emitting radioactive elements handled by nuclear industry workers and are part of the NRBC threat (nuclear, radiological, biological, and chemical). Skin contamination represents a major exposure route for these radioelements. Skin decontamination is therefore essential to prevent any dispersion of contamination and systemic absorption through the skin. This work focused the evaluation of skin penetration behavior of two actinides: americium and plutonium, in different forms, in an ex vivo model, pig ear skin. The decontamination efficacy of various products was tested on this model as well as an in vitro model of bovine hide powder. The efficacy of a new DTPA hydrogel formulation was also tested. The localization of in different skin layers was carried out using various imaging techniques: emulsion autoradiography, solid track autoradiography, TASTRAK or iQID camera. Data showed differences in penetration, retention and localization profiles of the different actinides used in moderately soluble aqueous solution or in a solvent mixture. In addition, the latter modifies skin structure that is associated with an increase in skin penetration. Radioactivity activity measurements in skin layers agreed well with distribution as shown by the different autoradiography techniques. The results of decontamination protocols showed an equal efficacy of the soap (Trait rouge®) as compared to DTPA, that is used for decorporation therapy and also for decontamination. The hydrogel formulation showed a superior efficacy for the treatment of organic solutions and demonstrates the interest for development of other pharmaceutical formulations

L’augmentation des activités humaines dans le domaine nucléaire civil comme militaire est à l’origine d’une dissémination effective ou potentielle de radionucléides dans l’environnement. Leur mobilité dépend de plusieurs facteurs tels que le pH, la force ionique, le degré d’oxydation et la présence de ligands organiques. Afin de garantir la sûreté de sites d’entreposage ou de stockage, de développer des procédés de remédiation de sols contaminés, il est nécessaire de disposer de données fondamentales sur les interactions entre actinides et ligands organiques susceptibles d’être présents dans l’environnement, vecteurs de migration ou de piégeage de ces radioéléments. Dans ce contexte, l’étude s’est axée sur les interactions entre Th(IV), U(IV,VI), Cf(III) and Eu(III) et des dérivés hydroxamates, en particulier, la desferrioxamine B, un sidérophore bactérien comportant trois fonctions hydroxamiques. Les constantes de formation des complexes sont déterminées en fonction de l’acidité et de la concentration de ligand à force ionique et température fixées en mettant en jeu plusieurs techniques expérimentales et des concentrations en élément comprises entre 10⁻¹⁰ et 10⁻³ M (extraction liquide-liquide combinée à une détection par spectrométrie γ, électrophorèse capillaire avec détection UV, spectrophotométrie d’absorption UV-visible). L’approche thermodynamique de cette étude est complétée par une étude structurale à l’aide de techniques spectroscopiques telles que la spectroscopie infrarouge à transformée de Fourier et de la spectroscopie d’absorption des rayons X. Ces mesures expérimentales sont alors confrontées à des calculs théoriques (DFT), afin de déterminer l’arrangement structural du métal et les distances interatomiques. / Due to the increasing human activities in the civilian nuclear fields, the actual and potential release of radionuclides into the environment is a matter of concern. The mobility of radio-nuclides depends on several factors such as pH, ionic strength, oxidation state and the presence of organic ligands. In order to guarantee the safety of radioactive waste storage sites and to develop contaminated soil remediation processes, it is necessary to have fundamental data on actinides and natural organic ligands interactions. This study focuses on the interaction between Th(IV), U(IV,VI), Cf(III) and Eu(III) and hydroxamates derivatives, desferrioxamine B, a bacterial siderophore with three hydroxamic functions. The stability constants of complexes are determined as function of acidity and ligand concentration, at fixed ionic strength and temperature, using several techniques and metal concentrations ranging from 10⁻¹⁰ to 10⁻³ M (liquid-liquid extraction coupled with γ-spectrometry, capillary electrophoresis with UV detection, UV-Vis absorption spectrophotometry). The thermodynamic study is supplemented by a structural one using spectroscopic techniques such as Fourier transform infrared spectroscopy and X-ray absorption spectroscopy. Experimental measurements are compared with quantum chemistry calculations (DFT) in order to determine the coordination geometry of the metal ion and the interatomic distances.

<p>It is well-known that f-block elements can exhibit coordination modes which surpass those of the transition metals. With uranyl and uranium bis(imido) complexes a strong preference is shown for the oxo or imido ligands in the <i>trans-</i> position; a phenomenon which is known as the inverse trans- influence which is unique to high valent actinides. However, when a third imido is added to the complex, a decrease in bond order occurs and this preference is diminished. Through the synthesis of several novel coordination complexes of tris(2,6-diisopropylphenyl)imido uranium [U(NDipp)₃] with a variety of ligands, we were able to analyze the energy differentials between bonding modes in both the solution and solid state. Furthermore, density functional theory calculations were employed to model the energetic preferences between these geometries. The combination of analyses gives rise to the observation that the orientation of the imido substituents is fluxional depending on the rigidity of the supporting ligands, and oftentimes exhibits low energetic barriers for the formation of different conformers.</p> <p> Uranium tris(imido) species bearing <i>trans</i>-imidos are desirable synthons as they can be used to mimic reactivity of more complicated uranium oxide polymeric systems. Such systems are advantageous as they are easily soluble in organic solvents, making them amenable to standard characterization methods and ligand substitution strategies. Our group has previously shown that uranium tris(imidos), easily synthesized from [(^MesPDI^Me)U(THF)]₂ and various azides, feature axial imido substituents exhibiting differing bond characteristics than the adjacent equatorial imido substituent. The aim of this work is to show that multiple analogues of mixed imido products can be formed from either the aforementioned dimer or stable tris(imido) synthons by exploiting reactivity differences between the axial and equatorial positions. </p> Presented herein are novel copper-​catalyzed ring opening reactions of cyclopropanols and various electrophiles to synthesize a variety of beta-​functionalized ketones. The reactions feature mild conditions and tolerates a wide selection of functional groups leading to complex products which can be used in the synthesis of bioactive molecules.

This report is concerned with the question whether Accelerator mass spectrometry (AMS) is asuitable technique for measuring actinide inventory in spent nuclear fuel, and if it is better thanpresent techniques for these measurements. AMS is a kind of Mass spectrometry (MS) and has alot of applications where radio carbon dating is one of the most common. AMS has been used formaking measurements on actinides before but mostly from traces in bioassay that could have beenin contact with weapon plutonium, and in bioassay near enrichment plants and reprocessingplants. It is shown in this report that AMS is more sensitive in low level measurements than thecurrent technique for spent nuclear fuel. ICP-MS is the current technique in use for inventorymeasurements on nuclear fuel at Swedish Nuclear Fuel and Waste Management Company (SKB).ICP-MS is also a kind of MS technique which is well-tried for inventory measurements on spentnuclear fuel. The difference in sensitivity ranges in levels of magnitude depending on whichisotope that is interesting for measurements. The lower detection limits for AMS is about 105-107atoms which makes it possible to use samples from nuclear fuel that is in the order of 10-10-10-16gto achieve the lower detection limit. The recommendation from this report is to make studies ifAMS also is an economical and efficiently suitable technique for future use on the actinideinventory in spent nuclear fuel. / Denna rapport handlar om huruvida Accelerator masspektrometri (AMS) är en lämplig teknik förmätning av aktinidinventeriet i använt kärnbränsle. Rapporten går också igenom om AMS är bättreän nuvarande tekniker för dessa mätningar. AMS är en typ av masspektrometri (MS) och har enmängd användningsområden, kol-14 metoden är en av de vanligaste. AMS har också ofta använtsför att göra mätningar på aktinidinnehåll i biomassa som kan ha varit i kontakt medvapenplutonium, och i närheten av anrikningsanläggningar och upparbetningsanläggningar. Detvisas i rapporten att AMS är en mer känslig metod än de nuvarande teknikerna som används förmätningar på aktinidinventariet i använt kärnbränsle. ICP-MS är den aktuella teknik som användsför mätningar på aktinidinventariet i använt kärnbränsle vid Svenska Kärnbränslehantering AB(SKB). ICP-MS är också en typ av MS teknik. MS är väl beprövad för mätningar av inventariet påanvänt kärnbränsle. Skillnaden i känslighet varierar i flera storleksordningar beroende på vilkenisotop som är intressant för mätningarna. Den lägre detektionsgränsen för AMS är cirka 105-107atomer, vilket gör det möjligt att använda prover från kärnbränsle som är i storleksordningen 10-10-10-16g för att uppnå den lägre detektionsgränsen. Rekommendationen från denna rapport är attgöra undersökningar om AMS också är ekonomiskt lönsam och tillräckligt effektiv teknik förframtida bruk inom mätningar av aktinidinventariet i använt kärnbränsle.

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