La connaissance du comportement sous irradiation γ et en présence d'eau des Résines Echangeuses d'Ions est nécessaire pour prévoir leur impact sur l'environnement pendant la phase d'entreposage et dans un éventuel stockage en profondeur géologique. Les REI étudiées sont la résine MB400 en lit mélangé ainsi que ses composants anionique et cationique « purs ». La stratégie expérimentale suivie a été basée sur l'utilisation d'outils chimiométriques qui ont permis d'étudier l'effet du milieu d'irradiation, du débit de dose, de la dose et de la température de lixiviation. Les produits de radiolyse gazeux et hydrosolubles ont été analysés par Spectrométrie de Masse gaz et Chromatographie Ionique. Les REI génèrent principalement du H2g, du CO2g et des amines dont les quantités dépendent de la nature de la résine et des conditions d'irradiation. L'analyse des résines solides irradiées a été effectuée par spectroscopie Infrarouge à Transformée de Fourrier et par Résonance Magnétique Nucléaire. Ces techniques révèlent des modifications structurales différentes suivant les conditions d'irradiation. Le comportement sous eau des REI a été étudié sur une période de 143 jours en caractérisant la matière organique relarguée après lixiviation post-irradiation. Les études cinétiques montrent qu'au premier contact avec l'eau, toutes les espèces hydrosolubles sont relarguées. La quantité de Carbone Organique Total dépend, selon la nature de la résine, soit de la dose, soit du milieu d'irradiation. Le débit de dose n'a pas d'effet sur la dégradation et la lixiviation de la résine MB400 qui, néanmoins se comporte d'une façon différente de ses composants pris séparément. / The knowledge of the behavior under irradiation and in presence of water of Ion Exchange Resins (IER) is very necessary to predict their impact on the environment during the storage phase and in a possible deep geological disposal. The IER studied are the MB400 mixed bed resin and its « pure » anionic and cationic components. The experimental strategy used in this work was based on the use of chemometric tools permitting to estimate the effect of the irradiation atmosphere, the dose rate, the absorbed dose and the leaching temperature. The gaseous and water-soluble radiolysis products were analyzed by gas Mass Spectrometry (MS) and Ion Chromatography (IC). The IER generated principally H2g, CO2g and amines for which quantities depended of the resin nature and the irradiation conditions. The analysis of solid irradiated resins was investigated by Fourier Transformed Infrared (FTIR) and Nuclear Magnetic Resonance (13C NMR) techniques. The last ones revealed structural modifications of the IER solid matrix in function of the experimental conditions. Their behavior in presence of water was studied during 143 days by characterization of the organic matter released after their post-irradiation leaching. The kinetics showed that all the water-soluble components were releasing at the first contact with water. The Total Organic Carbon (TOC) quantity released depends, according to the resin nature, either on the dose, either on the irradiation atmosphere. The dose rate has no effect on the degradation and the leaching of the MB400 resin, which behaved differently than its pure components.

Au cours de ce travail de thèse, nous nous sommes focalisés sur deux aspects de la RMN du solide: i) la RMN double-résonance de noyaux de fréquences de Larmor proches, ii) la quantitativité des spectres RMN sous polarisation croisée (CPMAS). L’emploi d’une sonde RMN solide prototype multicanaux (1H/19F/X/Y/Z) nous a permis de développer des outils RMN originaux pour la caractérisation de matériaux fluorés et ou hétérogènes (principes actifs, matériaux poreux, polymères), notamment le triple transfert de polarisation (1H, 19F) -13C, le double-transfert en cascade, les découplages multiples, et autres expériences de double-résonance 1H-19F ou 13C-27Al. La séquence multiCP a ensuite été évaluée pour l’obtention de spectre RMN 13C ou 29Si quantitatifs et la caractérisation de matériaux ayant des temps de relaxation contrastés. Nous avons montré que la condition pour obtenir des spectres RMN multiCP quantitatifs est la présence d’un bain de spins 1H dense. Des mesures quantitatives pour des composés purs (acides aminés, principes actifs, excipients, polymères inorganiques) ou en mélanges ont ainsi été obtenues. Le multiCP a ensuite été utilisé pour caractériser la structure locale de polymères siliciés et la nature fine du système de protons dans des membranes de Nafion. Dans la continuité, nous avons étudié une formulation pharmaceutique. Dans ce système hétérogène, nous avons profité des contrastes de temps de relaxation pour distinguer et quantifier les molécules de principe actif à l’intérieur ou en dehors du surfactant. Nous avons également caractérisé les interactions de la molécule avec le surfactant et suivi sa libération dans différents milieux mimant les milieux physiologiques. L’ensemble de ces travaux offre de nouveaux outils RMN pour la caractérisation de la structure locale de matériaux hétérogènes. / During this work, two aspects of solid-state NMR have been investigated: i) double-resonance NMR of nuclei with close Larmor frequencies, ii) quantitative cross-polarization (CPMAS) measurements. The use of a prototype multichannel solid NMR probe (1H/19F/X/Y/Z) has allowed the development of original NMR tools for the structural characterization of fluorinated or heterogeneous materials (active principles, porous solids, polymers), in particular the triple polarization transfer (1H, 19F) -13C, double-transfer ‘en cascade’, multiple decoupling, and other 1H-19F ou 13C-27Al double-resonance experiments. The multiCP experiment has then been evaluated to get quantitative 13C and 29Si NMR spectra and to characterize materials with contrasted relaxation times. We have shown that the presence of dense proton bath was key to get quantitative data. Quantitative measurements were then obtained for pure solids (aminoacids, active principles, excipients, inorganic polymers) and mixtures. The multiCP has then been used to characterize the local structure of siliceous polymers and the nature of the proton spin system in Nafion membranes. Finally, we have studied a pharmaceutical formulation. In this heterogenous system, we have taken benefit from the contrasted relaxation times to distinguish molecules present inside or outside the surfactant. We have also characterized the interactions between the active principle and the surfactant and followed the drug release in various physiological media. The ensemble of this work provides new NMR tools for the characterization of the local structure of heterogeneous materials.

This work addresses the distribution of N-methylolacrylamide (NMA) units in crosslinking poly(vinyl acetate) (PVAc) adhesives. In this case, distribution refers to the three potential locations of polymerized NMA units in a latex: the water-phase, the surface of polymer particles, and the core of the polymer particles. The objective is to identify the distribution of NMA in three latices and to determine whether NMA distribution correlates with durability related performance. NMA distribution was studied via a series of variable temperature solution NMR experiments, while the durability-related performance was studied via mode I fracture mechanics tests. Studying the distribution of NMA required the use of isotopically labeled NMA. Both 15N-NMA and 13C, 15N-NMA were synthesized. Three NMA/vinyl acetate (VAc) latices were prepared. The NMA feed strategy was varied during each of the three emulsion copolymerizations. Latex characterization methods including differential scanning calorimetry (DSC), rheometry, particle size analysis, and scanning electron microscopy (SEM) were used to study the three latices. The solution NMR method to identify NMA distribution was performed on untreated latices and on washed latices. Washing techniques included membrane dialysis and centrifugation. Results revealed that the three latices had different NMA distributions, and that the distributions were related to the expected differences in microstructure. Latex 3 had ~ 80% core-NMA, while Latex 2 had ~ 80% surface-NMA. Latex 1 had a high proportion of surface-NMA (~60%), but also had the highest proportion of water-phase NMA (~ 20%). This high proportion of water-phase NMA could be responsible for the unique morphology Latex 1 exhibited in SEM studies. Mode I opening fracture mechanics studies were used to study adhesive performance. Specimens were analyzed after exposure to accelerated aging treatments. Latex 2 and Latex 3 exhibited very similar results, despite having very different NMA distributions. All three latices showed good durability related performance. In Latex 2 and Latex 3, the critical strain energy release rates (Gc) after accelerated aging treatments were statistically the same as the Gc of the control specimens. The most interesting finding was that the Latex 1 Gc values were significantly higher after accelerated aging. Latex 1 also had the highest proportion of water-phase NMA. Bondline images and SEM micrographs both indicated that the integrity of Latex 1 was least affected by the accelerated aging treatments. / Ph. D.

No description available.

L'acide docosahexaénoïque (DHA) est un acide gras polyinsaturé oméga-3 (AGPI [oméga]3) concentré dans le poisson. Il est l'AGPI [oméga]3 présent en plus grande quantité dans le cerveau. Une étude épidémiologique a démontré que la consommation de deux portions de poisson par semaine peut ralentir le rythme du déclin cognitif qui survient avec le vieillissement. Étude SUPPLÉMENT. Objectif : Évaluer le changement plasmatique en AGPI [oméga]3 chez des sujets jeunes et âgés lors d'une supplémentation en acide eicosapentaénoïque (EPA)/DHA. Résultats : Chez les sujets jeunes et âgés, le DHA (73 « 47% et 117 « 68 %) et l'EPA (133 « 67% et 97 « 52%) plasmatiques ont augmenté significativement (p < 0,05) avec la supplémentation. Le pourcentage de DHA était supérieur chez les sujets âgés par rapport aux sujets jeunes avec la supplémentation. Conclusion : Les différences observées entre les sujets jeunes et âgés suggèrent qu'il existe un changement dans le métabolisme du DHA avec le vieillissement. Étude TRACEUR. Objectif : Évaluer l'incorporation du DHA marqué au carbone 13 (indice supérieur 13]C-DHA) dans les lipides totaux plasmatiques et sa [bêta]-oxydation chez des participants jeunes et âgés en bonne santé. Résultats : Initialement, la concentration de DHA dans les lipides totaux plasmatiques était similaire entre les groupes. Le [indice supérieur 13]C-DHA avait tendance (p = 0,055) à s'incorporer davantage chez les participants âgés (0,80 « 0,35 nmol/ml) comparativement aux jeunes (0,35 « 0,12 nmol/ml) quatre heures après la prise du traceur. Conclusions : Ces résultats suggèrent que l'incorporation du DHA dans les lipides plasmatiques et sa [bêta]-oxydation dans les heures suivant son ingestion sont influencés par l'âge. La faible [bêta]-oxydation du DHA sur un mois montre qu'il est davantage conservé pour des rôles structuraux plutôt qu'à des fins énergétiques. Conclusion générale :L'âge est associé à une augmentation de l'incorporation du DHA dans les lipides plasmatiques qui se reflète par la plus grande augmentation du DHA dans le plasma lors d'une supplémentation chez des personnes âgées. À cause de sa plus grande incorporation, davantage de DHA est disponible pour la [bêta]-oxydation, ce qui explique la plus grande quantité de DHA [bêta]-oxydé chez les personnes âgées. Cependant la [bêta]-oxydation du DHA est trop faible pour entrer en contradiction avec les résultats obtenus lors de la supplémentation.--Résumé abrégé par UMI.

Some endophytes in mutualistic associations with Festuca, Lolium and other grass species produce insecticidal loline alkaloids (1-aminopyrrolizidines; LA). These loline alkaloids have a saturated pyrrolizidine ring system (two-rings sharing a carbon and nitrogen atom), a 1-amine substituted with methyl, acetyl, or formyl groups, and an oxygen bridge between C-2 and C-7. The development of a reliable system of production of LA in cultures of the Lolium pratense (meadow fescue) endophyte, Neotyphodium uncinatum, facilitated work on the LA biosynthetic pathway. N. uncinatum produced norloline, loline, methylloline, N-acetylnorloline (NANL), N-formylloline (NFL), and N-acetylloline as detected in culture filtrates. The total production of the two most abundant alkaloids, NANL and NFL, approached 1000 g ml-1 of fungal filtrate. 1H and 13C chemical shifts were previously reported for this group of alkaloids. Extraction and synthesis of sufficient quantities of the alkaloids allowed determination of previously unknown 15N chemical shifts of some LA. Knowledge of 13C and 15N chemical shifts allowed identification of precursors by feeding stable-isotope-labeled compounds. Initially, due to structural similarity to other plant pyrrolizidines, this study examined putrescine and spermidine as possible precursors to LA. Feeding of 14C putrescine to the fungal cultures failed to demonstrate any enrichment in the LA, but enriched spermidine. In contrast, cultures fed with positionally labeled 2H, 13C and 15N amino acids namely, L-ornithine, L-proline, L-aspartate, L-homoserine, and L-methionine demonstrated specific isotopic enrichment in NFL. Determination of the enrichment from the labeled amino acids utilized 13C and 15 N NMR (nuclear magnetic resonance) and gas chromatography-mass spectroscopy (GC-MS). This study allowed the biosynthetic origins of all carbons and nitrogens of NFL to be determined. NFL incorporated L-proline into the B-ring and L-homoserine into the A-ring and 1-amine. The results strongly indicated that polyamines are not precursors of LA and implicated a novel biochemical pathway for the synthesis of LA.

A 13C-Análise de Fluxos Metabólicos (13C-MFA) tornou-se uma técnica de alta precisão para estimar fluxos metabólicos e obter informações importantes sobre o metabolismo. Este método consiste em procedimentos experimentais, técnicas de medição e em cálculos para análise de dados. Neste contexto, os grupos de pesquisa de engenharia metabólica necessitam de ferramentas computacionais precisas e adequadas aos seus objetos de estudo. No presente trabalho, foi construída uma ferramenta computacional na plataforma MATLAB que executa cálculos de 13C-MFA, com balanços de metabólitos e cumômeros. Além disso, um módulo para estimar os fluxos metabólicos e um módulo para quantificar as incertezas das estimativas também foram implementados. O programa foi validado com dados presentes na literatura e aplicado a estudos de caso. Na estimação de fluxos de Pseudomonas sp. LFM046, identificou-se que esse micro-organismo possivelmente utiliza a Via das Pentoses em conjunto com a Via Entner-Doudoroff para a biossíntese de Polihidroxialcanoato (PHA). No design ótimo de experimentos para uma rede genérica de Pseudomonas, identificou-se a glicose marcada no átomo cinco como um substrato que permitirá determinar o fluxo na Via das Pentoses com menor incerteza. / 13C-Metabolic Flux Analysis (13C-MFA) has become a high-precision technique to estimate metabolic fluxes and get insights into metabolism. This method consists of experimental procedures, measurement techniques and data analysis calculations. In this context, metabolic engineering research groups demand accurate and suitable computational tools to perform the calculations. A computational tool was implemented in MATLAB platform that performs 13C-MFA calculation, using metabolite and cumomer balances, as well as a module to estimate the fluxes and a module to quantify their uncertainty. The program was validated with some classical cases from literature. From the flux estimates of Pseudomonas sp. LFM046, it was identified that the microorganism possibly uses the Pentose Phosphate Pathway along with the Entner-Doudoroff Pathway for Polyhydroxyalkanoate (PHA) biosynthesis. From the optimal experimental design for a generic Pseudomonas network, it was possible to conclude that glucose labeled at atom five is the best option to determine the flux in the Pentose Phosphate Pathway with smaller uncertainty.

A unique characteristic of NMR is that, unlike other spectroscopic techniques, it separates the excitation of signals from their detection. By manipulating the type of signal excitation used, the chemical information content of a spectrum can be controlled. This versatility has made NMR a powerful and flexible weapon in the analytical arsenal of chemists, not only for the determination of structural, chemical, dynamic, and physical properties of molecules, but also for the analysis of mixtures, since NMR has the ability to study these intact without the need for physical separation. Chapter 1 contains an introduction to the theoretical NMR background necessary for this thesis. Chapter 2, 3 and 6 detail the development of new methods that suppress 13C satellites not only in conventional 1D 1H and 19F spectra, but also in 1H DOSY spectra, and can facilitate the analysis of minor components in high dynamic range mixtures (i.e. those with a wide range of concentrations). Chapter 4 introduces a new experiment which suppresses low-level artefacts in pure shift NMR, and gives clean pure shift spectra that can be used for the detection of minor components in the presence of strong signals. Chapter 5 and 7 illustrate how 19F NMR can be exploited for the acquisition of simplified proton spectra associated with a given 19F chemical shift, or for the virtual separation of mixture components using broadband 19F DOSY. Chapter 8 summarises the conclusions extracted from the research introduced in the main body of this thesis, and gives suggestions for future developments. Chapters 2, 3, 4, 5, and 7 contain published research articles and their Supporting Information and are presented without modification. Chapter 6 is presented as a manuscript intended for publication.

Le cycle de la matière organique à l'échelle continentale reste encore en partie méconnu. Ainsi, le COD a surtout été étudié sous un aspect chimique indifférencié. Des études isotopiques et l'utilisation de biomarqueurs ont permis d'élucider certains aspects de son cycle. La présente étude s'inscrit dans cette perspective. Deux types de milieux distincts, le fleuve Saint-Laurent et l'aquifère de l'Astien (France), ont été examinés. Dans le volet "Saint-Laurent", nous nous sommes intéressés au cycle du carbone organique terrigène (COT) à partir de mesures 13C et 14C du COD et d'une composante réfractaire du COD afin de comprendre l'origine et l'évolution du COT lors de son transit vers l'océan. Dans le second volet, les mêmes approches ont été retenues afin de déterminer la nature, les sources, l'état de dégradation et l'évolution temporelle du COD dans une nappe d'eau souterraine. Nous retenons une origine majoritairement terrigène pour le COD du Saint-Laurent, ainsi que son âge globalement très récent. Cependant, une fraction de ce COD est apparue beaucoup plus ancienne. La présente étude indique que le COD total du système hydrologique du fleuve Saint-Laurent est en majorité constitué de composés organiques facilement biominéralisables et donc potentiellement grands consommateurs d'oxygène dissous. Le COT pourrait donc jouer un rôle plus important qu'estimé aujourd'hui dans l'apparition de conditions hypoxiques dans les estuaires et zones côtières du globe. Dans le système de l'aquifère de l'Astien, les cinétiques relatives de dégradation des composés organiques issus de la macromolécule ligneuse pourraient donner lieu à des applications géochronométriques.

<p>This thesis presents the application of some of the NMR methods in studying host-guest complexes, mainly in solution. The general focus of the work is on investigating the reorientational dynamics of some small molecules that are bound inside cavities of larger moieties. In the current work, these moieties belong to two groups: cryptophanes and cyclodextrins. Depending on the structure of the cavities, properties of the guest molecules and the formed complexes vary. Chloroform and dichloromethane are in slow exchange between the cage-like cavity of the cryptophanes and the solvent, on the chemical shift time scale, whereas adamantanecarboxylic acid, quinuclidine and 1,7-heptanediol in complex with cyclodextrins are examples of fast exchange. Kinetics and thermodynamics of complexation are studied by measuring exchange rates and translational self-diffusion coefficients by means of 1-dimenssional exchange spectroscopy and pulsed-field gradient (PFG) NMR methods, respectively. The association constants, calculated using the above information give estimates of the thermodynamic stability of the complexes. Carbon-13 spin relaxation data were obtained using conventional relaxation experiments, such as inversion recovery and dynamic NOE, and in some cases HSQC-type (Hetereonuclear Single Quantum Correlation Spectroscopy) experiments. Motional parameters for the free and bound guest, and the host molecules were extracted using different motional models, such as Lipari-Szabo, axially symmetric rigid body, and Clore models. Comparing the overall correlation times and the order parameters of the free and bound guest with the overall correlation time of the host molecule one can estimate the degree of the motional restriction, brought by the complexation, and the coupling between the motion of the bound guest and the reorientation of the host molecule. In one case, the guest motions were also investigated inside the cavities of a solid host material.</p>