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Le déploiement des futurs réacteurs à neutrons rapides, dits de Génération IV, est porteur d'améliorations prometteuses sur le plan de l'utilisation des matières premières et de la gestion des déchets. Elles s'accompagneront d'une transformation majeure du cycle et du développement de nouveaux procédés de recyclage, plus simples et plus efficaces. Une des conséquences de cette évolution est l’augmentation de la quantité de radionucléides à vie longue (RNVL) le carbone 14, l’iode 129 et le chlore 36 dans le combustible irradié, rejets du cycle nucléaire. La maîtrise et la réduction de ces rejets passe d’abord par une meilleure connaissance de la quantité de ces radionucléides dans le combustible, formés pendant son irradiation en réacteur. Ce travail de thèse s’inscrit dans l’objectif d’améliorer la mesure des radionucléides carbone 14, iode 129 et chlore 36 dans l’oxyde irradié, non seulement sur les performances analytiques mais aussi sur la minimisation des volumes de rejets liquides et solides engendrés. Une étude bibliographique a été menée afin d’établir le bilan des méthodes existantes pour la mesure de ces RNVL dans l’oxyde irradié. Les conclusions de cette étude ont orienté ce travail selon trois axes principaux : l’utilisation de l’ozone pour oxyder et désorber le carbone 14 de l’oxyde irradié après sa mise en solution ; la proposition d’une méthode d’extraction sélective du chlore 36 contenu dans l’oxyde irradié ; le développement d’une nouvelle méthode d’analyse alliant une séparation par chromatographie ionique couplée à une détection des émetteurs R par scintillation solide pour les trois RNVL / The deployment of future fast neutron reactors, called Generation IV, carries promising improvements in the use of raw materials and waste management. They will lead to a major transformation of the cycle and the development of new recycling processes which will be simplified and more effective. One consequence of this development is the increase of the amount of long-lived radionuclides in spent fuel nuclear waste: 14 carbon, 129 iodine and 36 chlorine. The control and reduction of these radionuclides begins with a better understanding of the amount of these radionuclides in the spent fuel, generated during irradiation in a reactor. The objective of this work consist in improving the measurement of 14 carbon , 129 iodine and 36 chlorine radionuclides in the irradiated oxide, all in reducing the liquid and solid waste generated. A bibliography study was conducted to evaluate the existing methods for measuring these radionuclides in irradiated oxide. The conclusions of this study have oriented the work in three main ways: the use of ozone to oxidize and desorb 14 carbon of the irradiated oxide after solution treatment; the proposal of a selective extraction method for 36 chlorine contained in the irradiated oxide; the development of a new analytical method combining a separation by ion chromatography coupled with detection of R solid scintillation for the three radionuclides

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Through underexpression and overexpression studies, CD23 has been shown to negatively regulate IgE production. To investigate CD23 destabilization and its effects on CD23 shedding and IgE synthesis in vivo, we utilized an anti-CD23 stalk monoclonal (19G5) which has previously been shown to enhance proteolysis of CD23 in vitro. Compared to isotype control-treated mice, mice injected with 19G5 displayed enhanced serum soluble CD23 and IgE. Because 19G5 injection substantially enhanced CD23 shedding, it was useful in investigating the identity of the CD23 sheddase. 19G5 enhanced CD23 shedding in ADAM8-/-, ADAM9-/-ADAM15-/-, and ADAM9-/-ADAM12-/-ADAM15-/- mice, ruling out these ADAMs as candidate CD23 sheddases. Through the use of an ADAM10 inhibitor, we blocked CD23 shedding from murine B cells while increasing CD23 surface levels, and thus we identified ADAM10 as the CD23 sheddase. During the course of the ADAM investigation, we discovered that the 129/SvJ inbred mouse strain carried five amino acid substitutions within its CD23 gene. The mutations resulted in reduced CD23 surface expression and hyper IgE levels in vivo. The hyper IgE phenotype was consistent with a more rapid clearance of Nippostrongylus brasiliensis from the gut of 129/SvJ mice. B cells from 129/SvJ spleens proliferated more rapidly than those from BALB/c after stimulation with IL-4 and CD40 ligand trimer in vitro. However, in vitro IgE levels in supernatants from 129/SvJ B cells were significantly reduced, suggesting that the B cells were no longer responsive to IL-4 in vitro. Although the affinity of the IgE-129/SvJ CD23 interaction was similar to that of the BALB/c, 129/SvJ B cells exhibited a reduced number of IgE binding sites, demonstrating that high levels of CD23 are essential for controlling IgE synthesis. This finding was further confirmed in another disease model, namely the mouse asthma model. Mice overexpressing CD23 displayed suppressed allergic lung inflammation and reduced levels of IgE and Th2 cytokines and chemokines. Overall, the data provide a direct demonstration for CD23's role in regulating IgE production in vivo and suggest that therapies aimed at stabilizing cell surface CD23 would inhibit proteolysis and increase surface expression, and thus would be beneficial in controlling allergic disease.

Dans les milieux liquides où la polarisation et la densité de spins nucléaires sont importantes, la dynamique de l'aimantation, analysée par RMN (résonance magnétique nucléaire), est perturbée par les couplages internes induits par les champs magnétiques dipolaires locaux. Le présent mémoire décrit certaines conséquences associées à la présence dans l'échantillon d'une forte concentration de 129Xe hyperpolarisé par pompage optique (polarisation jusqu'à 20%), notamment les modifications des spectres RMN du proton et du xénon en présence. Puis nous présentons les résultats de l'expérience SPIDER, ayant pour but de transférer de façon cohérente la polarisation du xénon aux protons d'aimantation thermique afin d'accroître leur signal RMN. Ensuite, nous décrivons l'apparition d'émissions maser chaotiques répétées, dues au couplage inductif entre l'aimantation du xénon dans un état instable et la bobine d'analyse accordée à sa fréquence de Larmor (ici 138 MHz). Enfin, nous présentons dans la dernière partie une nouvelle méthode d'accord d'une sonde RMN permettant dans certaines conditions de réception un gain important en sensibilité et en forme de signaux, avant de conclure sur les limites de la théorie classique de la relaxation dans le cas des fortes aimantations en phase liquide.

The purpose of this study was to investigate the views of elementary school teachers about their implementation of assessment techniques recommended in the new mathematics curriculum. The study was conducted with 306 elementary school teachers from 29 public schools in Kirikkale, Malatya and Ankara in the 2006-2007 academic year. &lsquo / Opinions about Assessment Questionnaire&rsquo / was used as the instrument for assessing the opinions of the teachers about assessment techniques offered in new mathematics curriculum. The results showed that, teachers did not have negative views towards the implementation of the new assessment techniques in mathematics lessons. However, they needed support from curriculum experts about more suitable implementation of the assessment process. To assess the effects of teaching experience, class size and grade level they teach on the views of the teachers about their implementation of assessment techniques recommended in new mathematics curriculum, the Univariate Analysis of Variance was used. The results revealed that the opinions of the teachers about their implementation of assessment techniques offered in new mathematics curriculum did not show any significant difference according to the experience of the teachers, class size and grade level teachers teach.

129I is of major concern because of its biophilic nature, excessive inventory, long half-life (~16 million yrs), and high mobility in the natural environment that depends on its chemical speciation. Iodide (I-) has the highest mobility than iodate (IO3-) and is the predominant species in the terrestrial environment due to prevailing pH and Eh conditions. In order to transform I- to less mobile organo-iodine (OI), strong oxidants are necessary to activate the first electron transfer step from I- to reactive intermediates. The aim of this study was to determine the influence of naturally occurring aerobic bacteria isolated from an 129I contaminated aquifer (F-area of the Savannah River Site, SC) on I- oxidation and OI formation. It was demonstrated that 3 of 136 strains accumulated I- (0.2~2%) in the presence of H2O2, when incubated in the presence of an environmentally relevant concentration of I- (0.1 microM). The accumulation was likely through electrophilic substitution resulting in the iodination of cellular constituents. The results indicated that culturable I--accumulating bacteria are not directly responsible for the high fraction of oxidized iodine species (IO3- and OI, >50% of total I) present in the SRS F-area. Several bacterial strains were found to be capable of stimulating I- oxidation through excretion of oxidants and enzymes. Organic acids in spent liquid medium from 27 of 84 aerobic bacterial cultures enhanced H2O2-dependent I- oxidation 2-10 fold. Organic acids enhanced I- oxidation by (1) lowering the pH of the spent medium and (2) reacting with H2O2 to form peroxy carboxylic acids, which are strong oxidizing agents. In the absence of H2O2, spent medium from 44 of 84 bacteria cultures showed I- oxidizing capacities. One I- oxidizing bacterium was studied to characterize its extracellular I- oxidizing component(s). The I- oxidizing capability from the spent medium was inactive by treatments with heat and H2O2 and absent under anaerobic conditions. Conversely, NADH, NADPH and FMN additions stimulated I- oxidation in the spend medium. These results indicate an oxidase(s) catalyzed I- oxidation. Understanding the bacterial activities involved with I- oxidation and OI formation is expected to help reduce 129I mobility in water-soil systems.

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Iodine-129 is a naturally and anthropogenically produced radioisotope (half-life: 15.7 million years) the majority of which is produced by nuclear fuel reprocessing. These releases have dispersed 129I throughout the environment making it possible to use 129I as a tracer. It is also of concern for the disposal of radioactive waste. This research develops a new laboratory method for 129I extraction and analysis, and explores the geochemical cycling and environmental fate of 129I in remote catchments following the Fukushima-Daiichi Nuclear Accident (FDNA). A new technique was developed to investigate 129I partitioning and quantitatively extract it from solid samples. Samples are combusted and volatilized iodine is trapped in solution. The efficiency is traced using the iodine isotope, 125I. This technique was proven using standard reference materials and is used in other chapters of this thesis. A baseline study of 129I in Yukon watersheds was undertaken to determine the impact of anthropogenic 129I emissions and identify possible sources. Using atmospheric back-trajectory modeling, sources of 129I from Fukushima, nuclear fuel reprocessing and marine volatilization were identified in remote watersheds. Peat moss samples showed significant retention of 129I in modern samples. Following the reconnaissance study, a catchment scale investigation of anthropogenic 129I cycling was undertaken through precipitation and runoff monitoring. 129I was found to be an excellent indicator of initial snowmelt contributions to discharge due to enrichment by dry deposition. Furthermore, water source transitions in discharge were recorded by 129I, 127I and the 129I/127I ratio showing iodine can be used as a tracer of hydrologic processes. A mass balance found that 77% of the 129I mass input accumulates annually, primarily in organic soils. Sampling of Vancouver, B.C. precipitation and groundwater was done following the FDNA to determine the fate of 129I and evaluate it as a tracer of groundwater recharge. Immediately following the FDNA the 129I concentration in precipitation increased 6 times above background. Groundwater samples also showed 129I increases consistent with expected recharge times indicating FDNA derived 129I was transported into groundwater with minimal retardation, likely via preferential flowpaths.

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