Les techniques d'acquisition des signaux médicaux sont en constante évolution et fournissent une quantité croissante de données hétérogènes qui doivent être analysées par le médecin. Dans ce contexte, des méthodes automatiques de traitement des signaux médicaux sont régulièrement proposées pour aider l'expert dans l'analyse qualitative et quantitative en facilitant leur interprétation. Ces méthodes doivent tenir compte de la physique de l'acquisition, de l'a priori que nous avons sur ces signaux et de la quantité de données à analyser pour une interprétation plus précise et plus fiable. Dans cette thèse, l'analyse des tissus biologique par spectroscopie RMN et la recherche des activités fonctionnelles cérébrales et leurs connectivités par IRMf sont explorées pour la recherche de nouveaux bio-marqueurs. Chaque information médicale sera caractérisée par un ensemble d'objets que nous cherchons à extraire, à aligner, et à coder. Le regroupement de ces objets par la mesure de leur similitude permettra leur classification et l'identification de bio-marqueurs. C'est ce schéma global d'indexation et de recherche par le contenu d'objets pour la détection des bio-marqueurs que nous proposons. Pour cela, nous nous sommes intéressés dans cette thèse à modéliser et intégrer les connaissances a priori que nous avons sur ces signaux biologiques permettant ainsi de proposer des méthodes appropriées à chaque étape d'indexation et à chaque type de signal.

Spruce Bark contains several fundamental main substances; lignin, non-cellulose polysaccharides, cellulose and extractives. This undergraduate study focuses on developing a process to extract each of these components from spruce bark using a biorefinery concept, with a main focus on extracting lignin without degradation. The purpose of the Bark biorefinery concept is to contribute to a circular bioeconomy, by making use of natural resources. With extended research on the area, it will be possible to produce polymers, green chemicals and biofuel from the components in bark.  This report covers the extraction of the bark components with soxhlet extraction, Hot-water extraction, organosolv extraction and peracetic acid delignification. The extraction was made on two samples, matchstick-sized bark (MS) and 20 mesh-sized bark with a diameter of 0.8 mm (20M). The purpose was to be able to compare the efficiency of the extraction between the two samples. Afterwards, the characterisation of extracts and residue was executed with carbohydrate analysis, 2D HSQC-NMR and FTIR-analysis.  The results showed that a smaller particle size led to more efficient extractions of all components as well as more pure extract solutions. Lignin concentration determinations of samples at each step showed that a significant amount of lignin was lost prior to the organosolv extraction. Future research should look into ways to reduce this loss in order to increase the lignin yield. The findings in the FTIR and NMR analyses correlates with what could be seen in other reports, discussing similar subjects. For upscaling of this process, future research should go toward optimization of all extraction methods in order to make an upscaling of the process economically viable.

Spin selective MQ-SQ correlation has been demonstrated by either selective pulses in homo-nuclear spin systems in isotropic and weakly orienting chiral media or by nonselective pulses in hetero-nuclear spin systems in strongly aligned media. As a consequence of the spin selective correlation, the coherence transfer pathway from MQ to SQ is spin state selective. This two dimensional approach enables the utilization of the passive couplings (remote couplings) to break a complex one dimensional spectrum into many sub spectra. Each sub spectrum contains fewer transitions and hence fewer couplings (active couplings). The role of the passive couplings is to displace the sub spectra and measurement of the displacements taking into account their relative tilt provides the magnitude of the passive couplings along with relative signs. Further possibility of a spin state selective MQ-SQ resolved experiment to determine very small remote couplings otherwise buried within linewidth in one dimensional spectrum has been demonstrated. The resolution of the multiple quantum spectrum in indirect dimension has also been exploited to separate the sub spectra. The technique renders the analysis of complex spectrum in isotropic system much simpler. The potentialities of the technique have also been demonstrated for discrimination of optical enantiomers and derivation of the residual dipolar couplings from very complicated spectrum. The second order spectrum in strongly aligned media restrict selective excitation, however in hetero-nuclear spin system the nonselective pulses on protons do not interact with the hetero-nuclear spins. Thus the weakly coupled part of a strongly coupled spectrum has been exploited for simplifying the second order spectrum and thereby its analysis. Thus several methodologies derived from spin selective correlation has been demonstrated. Enantiopure spectrum has been recorded from a mixture of R and S enantiomers by a novel pulse scheme called Double Quantum Selective Refocusing Experiment. The dipolar coupled methyl protons in weakly orienting media are utilized. The selective excitation of double quantum coherence reduces the three spin system into a two spin system and remote couplings are refocused which otherwise leads to broadening. The sum of passive couplings being different for the enantiomers resolution in the DQ dimension is enhanced and thereby their discrimination. Finally several decoupling schemes has been compared in the indirect dimension of HSQC experiment to resolve 13C satellite spectra otherwise buried within line width for increased confidence in determining hetero-nuclear framework information.