Die Aufgabenstellung dieser Arbeit bestand in der Entwicklung und Umsetzung von Verfahren, mit denen die Durchblutung des menschlichen Herzmuskels quantitativ bestimmt werden kann. Im Rahmen dieser Arbeit wurden dazu zwei Ansätze verfolgt, das kontrastmittelfreie Spin-Labeling Verfahren und die kontrastmittelgestützte First-Pass Messung / The goal of this dissertation was the developement and implementation of methods to quantify the microcirculation of the human heart. To this end, two approaches were investigated, a contrast agent free spin-labeling technique, and a contrast agent based First-Pass technique.

Neisseria meningitidis ist eine der führenden Ursachen von Morbidität und Mortalität sowohl bei Kindern als auch bei Erwachsenen. Die Typisierung ist die Grundlage für die epidemiologische Überwachung der Erkrankung durch Meningokokken. Die Endonuklease NmeDI ist spezifisch für die klonalen Linien des ST-8 und ST-11 Komplex Meninkokken, die mit Erkrankungen der Serogruppe C assoziiert sind. Deshalb wurde für die rasche Identifizierung von Stämmen dieser Linien ein monoklonaler Antikörper entwickelt. Der Antikörper erkennt spezifisch die ST-8 und ST-11 Komplex Meningokokken in Western-Blot und Dot-Blot. Er wird mitlerweile routinemäßig im Nationalen Referenzzentrum für Meningokokken zur Identifizierung der Linien ohne zusätzliche Anwendung der Multilokus Sequenz Typisierung (MLST) eingesetzt. / Neisseria meningitidis is a leading cause of morbidity and mortality in children and adolescents. Typing is essential for epidemiological surveillance of meningococcal disease. The endonuclease NmeDI is specific to the clonal lineages ST-8 and ST-11 complex associated with serogroup C disease. Therefore, a monoclonal antibody was developed for rapid identification of strains belonging to these lineages. The antibody specifically recognized ST-8 and ST-11 complex meningococci in Western blots and dot blots. It is now routinely used at the German National reference centre for meningococci for presumptive identification of the lineages without multilocus sequence typing.

Virtually all existing MRI applications require both a high spatial and high temporal resolution for optimum detection and classification of the state of disease. The main strategy to meet the increasing demands of advanced diagnostic imaging applications has been the steady improvement of gradient systems, which provide increased gradient strengths and faster switching times. Rapid imaging techniques and the advances in gradient performance have significantly reduced acquisition times from about an hour to several minutes or seconds. In order to further increase imaging speed, much higher gradient strengths and much faster switching times are required which are technically challenging to provide. In addition to significant hardware costs, peripheral neuro-stimulations and the surpassing of admissable acoustic noise levels may occur. Today’s whole body gradient systems already operate just below the allowed safety levels. For these reasons, alternative strategies are needed to bypass these limitations. The greatest progress in further increasing imaging speed has been the development of multi-coil arrays and the advent of partially parallel acquisition (PPA) techniques in the late 1990’s. Within the last years, parallel imaging methods have become commercially available,and are therefore ready for broad clinical use. The basic feature of parallel imaging is a scan time reduction, applicable to nearly any available MRI method, while maintaining the contrast behavior without requiring higher gradient system performance. PPA operates by allowing an array of receiver surface coils, positioned around the object under investigation, to partially replace time-consuming spatial encoding which normally is performed by switching magnetic field gradients. Using this strategy, spatial resolution can be improved given a specific imaging time, or scan times can be reduced at a given spatial resolution. Furthermore, in some cases, PPA can even be used to reduce image artifacts. Unfortunately, parallel imaging is associated with a loss in signal-to-noise ratio (SNR) and therefore is limited to applications which do not already operate at the SNR limit. An additional limitation is the fact that the coil array must provide sufficient sensitivity variations throughout the object under investigation in order to offer enough spatial encoding capacity. This doctoral thesis exhibits an overview of my research on the topic of efficient parallel imaging strategies. Based on existing parallel acquisition and reconstruction strategies, such as SENSE and GRAPPA, new concepts have been developed and transferred to potential clinical applications. / In den späten 80er Jahren entwickelte sich die Magnetresonanz-Tomographie (MRT), die bis dato lediglich in Forschungseinrichtungen etabliert war, zu einem der wichtigsten Verfahren in der klinischen Diagnostik. Allerdings erfordern nahezu alle bestehenden klinischen Anwendungsgebiete sowohl eine hohe räumliche als auch eine hohe zeitliche Auflösung für eine optimale Detektion und Klassifizierung von Krankheitsbildern. Der bisherige Ansatz, diesen zunehmenden Anforderungen an die klinische MRT gerecht zu werden, bestand vor allem in der stetigen Verbesserung von Gradientensystemen die mit immer höheren Gradientenstärken und schnelleren Schaltzeiten aufwarteten. Die technischen Fortschritte, sowie schnelle Bildgebungsmethoden erlaubten es, Messzeiten von etwa einer Stunde auf nur wenige Minuten oder sogar Sekunden zu reduzieren. Eine weitere Verkürzung der Experimentdauer mittels noch leistungsfähigeren Gradientensystemen ist jedoch technisch schwierig zu realisieren. Ausserdem gehen enorm hohe Entwicklungs und Materialkosten mit den erhöhten Anforderungen einher. Es kommt hinzu, dass noch stärkere Gradienten und noch schnellere Schaltzeiten zu peripheren Neurostimulationen und zur Überschreitung von zulässigen akustischen Grenzwerten führen können. Heutige Gradientensysteme arbeiten schon sehr nahe an den Grenzen der zulässigen Sicherheitsbestimmungen. Deshalb werden alternative Strategien benötigt, um weitere Messzeitverkürzungen realisieren zu können. Der bisher erfolgreichste Ansatz bestand in der Entwicklung von Mehr-Kanal-Spulen-Anordnungen und damit verknüpft der darauffolgenden Einführung der parallellen Bildgebung in den späten 90er Jahren. In den letzten 5 Jahren haben sich parallele Bildgebungsmethoden an den klinischen Tomographen etabliert und nahezu alle Herstellerfirmen stellen diese Technik kommerziell zur Verfügung. Die parallele Bildgebung ermöglicht eine Messzeitverkürzung, die prinzipiell auf jede bestehende Bildgebungsmethode angewendet werden kann, ohne dabei das Kontrastverhalten zu verändern und ohne höhere Gradientenleistung zu beanspruchen. In der parallellen Bildgebung übernimmt die Mehr-Kanal-Spulen-Anordnung teilwiese die Ortskodierung, die normalerweise durch zeitaufwendiges Schalten von Magnetfelgradienten erzeugt wird. Mit dieser Strategie kann bei gleicher Messzeit die örtliche Auflösung verbessert, oder bei gleicher Auflösung die Messzeit verkürzt werden. Ausserdem können mit hilfe der parallelen MRT in manchen Fällen Bildartefakte signifikant reduziert werden. Allerdings ist mit der parallelen Bildgebung immer ein Signal zu Rausch (SNR) Verlust verbunden, der diese Methode auf klinische Anwendungen begrenzt, die nicht bereits am SNR-Limit betrieben werden. Ausserdem muß die Spulenanordnung genug Sensitivitätsvariationen über das zu untersuchende Objekt bereitstellen, um ausreichende Kodierfunktion zu gewährleisten. Diese Dissertationsarbeit liefert einen Überblick über meine Forschungsarbeit zum Thema “Entwicklung und Anwendung von effizienten Strategien in der parallelen MRT”. Basierend auf bestehenden parallelen Akquisitions und Rekonstruktionstechniken, wie beispielsweise SENSE und GRAPPA, wurden neue Konzepte entwickelt und auf mögliche klinische Fragestellungen angewandt.

Die Arbeit befaßt sich mit Methoden der 23Na-NMR-Bildgebung zur Diagnose am ischämischen und infarzierten Herzmuskel. Der erste Teil beschreibt eine Methode zur lokalisierten Messung des intra- und extrazellulären Natriumgehaltes und T1. Die Methode kam in einer Studie zum Einsatz, in der intra- und extrazellulärer Natriumgehalt sowie die T1-Werte an den Tagen 1, 3 und 21 nach Infarkt gemessen wurden.Im zweiten Teil der Arbeit wird die Dynamik des 23Na bei freier Präzession im stationären Zustand (SSFP) sowohl in numerischen Simulationen als auch experimentell untersucht. / Purpose of this work was the study and development of 23Na-NMR imaging methods for the diagnosis of ischemia and myocardial infarction. In a first part, a method to measure on a local basis the intra- and extracellular sodium contents and T1 values is described. The method has been applied to measure the intra- and extracellular sodium contents and T1 values in myocardial infarction on day 1, 3 and 21 post-infarction. In a second part, the dynamics of 23Na during completely balanced steady-state free precession have been studied in numerical simulations and experiments.

Neste trabalho, apresentamos um estudo por Ressonância Magnética Nuclear (RMN), Análises Termogravimétricas (DSC e TG) e Espectroscopia Infravermelho em cornplexos poliméricos formados entre poli(óxido de etileno), POE, e sais de lítio. Estes complexos tem mostrado uma grande potencialidade em aplicações tecnológicas (baterias, sensores, etc). Desenvolvemos e caracterizamos sensores de umidade e, discutimos como a umidade afeta a conformação do complexo e a mobilidade das espécies iônicas e da cadeia polimérica. Nossos resultados indicam que a hidratação afeta a conformação dos complexos poliméricos através do efeito plasticizante da água, o qual induz uma expansão volumétrica na cadeia do POE. Entretanto, para os níveis de hidratação utilizados, o processo mostrou-se completamente reversível. Através do estudo de RMN, conseguimos diferenciar os movimentos da cadeia polimérica daqueles das espécies iônicas (cátion e ânion). A análise do segundo momento das formas de linha de ressonância e os estudos de relaxação nuclear nos permitiu estimar distâncias médias entre as espécies iônicas e os prótons da cadela nestes complexos. Observamos também, que o comportamento da relaxação spin rede do hidrogênio e do flúor no P(OE)-LiBF4, em função da temperatura e da freqüência, reflete a natureza desordenada do material e a complexidade do processo de condução iônica nestes sistemas / In this work we report on a study using Nuclear Magnetic Resonance (NMR), Thermogravimetry Analysis (TGA), Differential Scanning Calorimetric (DSC) and Infrared Spectroscopy in polymeric complexes formed between poly(ethylene oxide), PEO), and lithium salts. These complexes have shown a large potential in for technological applications in batteries, sensors, etc. We developed and characterized humidity sensors and we discussed how the humidity affects the conformation of the complexes, the mobility of ionic species, and the polymeric chains. The results indicate that the hydration effects the conformation of polymeric complexes by plasticizing the water, which induces a volumetric expansion in the PEO chain. The process was completely reversible for the level of hydration studied. NMR was used to distinguish the movement of polymeric chains from the movement of the ionic species. From the analysis of the second moment of resonance lines and from the study of the nuclear relaxation we were able to estimate the average distance between the ionic species and the proton In the complexes chains. The behavior of spin-lattice relaxation of hydrogen and flurine in the P(EO) LiBF4 as a function of temperature and frequency reflects the nature of the disorder and the complexity of the ionic conduction process In these materials

Aconitum and Delphinium genera are important rich sources of toxic C19-diterpenoid alkaloids. The alkaloidal content of A. napellus and D. elatum seeds have been investigated in detail. After maceration, crude alkaloidal extracts were obtained and then purified by repeated column chromatography (over silica and alumina gels) to sample homogeneity yielding five known C19-diterpenoid alkaloids from A. napellus, aconitine, neoline, 14-O-acetyltalatisamine, 14-O-benzoylaconine, and taurenine, and two others from D. elatum, delpheline (also including its X-ray single crystal analysis) and methyllycaconitine (MLA). These examples showed that mass spectrometry hyphenated with HPLC or other chromatography can be used as a tool for rapid alkaloid content screening of different extracts. NMR spectroscopic (using a variety of techniques and nuclei) data are presented in support of the first report of iminodelsemine A/B as an imino-alkaloid artefact from D. elatum. A detailed chromatographic study across different pH ranges, and over different solid supports, of aconitine and its main degradation product, 14-O-benzoyl-8-O-methylaconine, together with its semi-synthesis and that of its deuterated analogue are reported within studies to minimize artefact formation during the storage or extraction of A. napellus norditerpenoid alkaloids. Likewise, from D. elatum seeds, as a model source of Delphinium alkaloids, we compared the alkaloid yield using different extraction techniques and conventional chromatographic separations. The structures were confirmed by NMR spectroscopy and mass spectrometry. An NMR spectroscopic approach for the pKa determination of some C19-diterpenoid alkaloids has been developed. A modified calculation method for fatty acid composition quantification has also been developed using 1H-NMR spectroscopic methods.

No description available.

Microporous catalysts belong to a class of materials that exhibit pore networks in the molecular dimension, that is, channel diameters less than 2 nm. The industrially most important microporous catalysts are zeolites, which are crystalline aluminosilicates and consist of interlinked alumina (AlO4) and silica (SiO4) tetrahedra forming pores and cavities of molecular dimensions. Zeolites can act as very strong solid acids and function as heterogeneous catalysts in various industrial processes used to obtain polyethylene terephthalate (PET) or polyvinyl chloride (PVC). They are crucial for products with a significant market demand such as plastics used in bottles, packaging materials and household consumable goods as well as for coatings of pharmaceutical pills and detergents. Recently, zeolites have been found to have increased applications in aqueous and biphasic reactions that use reactants derived from biomass to arrive at petrochemical products. Thus, surface acidity in zeolites is crucial to understand to tune parameters such as activity and selectivity of zeolite catalysts to optimize product distributions. The objective of this dissertation was to validate the use of non-invasive nuclear magnetic resonance (NMR) techniques to characterise surface acidity in zeolites by benchmarking the NMR results to various more established zeolite characterisation techniques, such as Fourier transform infrared (FTIR) spectroscopy and temperature-programmed desorption (TPD). Furthermore, the use of the tapered element oscillating microbalance (TEOM) to characterise internal and external acidity in zeolites was explored. IR and TPD techniques were used to assess important acidity parameters such as type, number, location and strength of acid sites of ZSM-5 zeolites with varying silica-alumina ratio (SAR = SiO2/Al2O3). The use of NMR relaxation time analysis of pyridine adsorbed in ZSM-5 was then explored as a model system to study surface acidity in microporous materials. Correlation with pyridine TPD results suggested that NMR relaxation time analysis probes the effective strength of pyridine adsorption sites, which varies with SAR. NMR relaxation time analysis was then further shown to be applicable to characterise non-acidic surface properties such as the hydrophilic and hydrophobic surface character. Lastly, the NMR techniques developed at high magnetic field strength (300 MHz) were transferred to a portable, low-cost benchtop low-field (43 MHz) magnet and shown to be applicable for base probe molecules other than pyridine, that is, ammonia (NH3) as well as zeolite framework types other than ZSM-5, that is, chabazite (CHA).

The nitrogen-vacancy (NV) centre in diamond has proven to be an excellent tool to probe electro-magnetic fields and temperature. It has a number of unique features: High sensitivity and resolution, long coherence and lifetimes, the ability to operate from cryogenic temperatures to hundreds of Kelvin, chemical inertness and addressability via optics and microwaves. Recent progress includes the detection of NMR and spectroscopy of single proteins on a diamond surface and in-vivo temperature measurements. However, while the NV centre in bulk diamond has received a lot of attention, the nitrogen-vacancy in nanodiamond has not been investigated extensively due its widely seen inferior properties. It is only very recently that problems with the stability of photoluminescence and short coherence times have been overcome. The NV centre in nanodiamond is thus increasingly seen as an interesting tool for research requiring nanoscale sensors, e.g. in cells. The findings of this thesis facilitate applications of the NV centre in nanodiamond and demonstrate its high potential for future research. Most notably, the nuclear host spin, which is intrinsic to the point defect, can be used to enhance sensitivity and resolution of measurements. In addition, the sensitivity can be improved by time-tagging the emission from the NV centre. Furthermore, the graphite layer covering nanodiamonds can be removed by annealing. This does not have negative effects on the spin properties of the hosted NV centres but enables functionalisation of the surface and therefore advanced in-vivo measurements. Finally, the capabilities of the NV centre in nanodiamond in investigating the formation of magnetic domains are demonstrated at low temperatures. These results enable and motivate the use of the NV centre in nanodiamond for future research, most especially in biological systems.

Supercapacitors (or electric double-layer capacitors) are high power energy storage devices that store charge by the non-faradaic adsorption of ions at the interface between porous carbon electrodes and an electrolyte solution. The development of new electrode materials and electrolytes with improved performances is an active area of research today, yet there are relatively few studies of the molecular mechanisms of the charge storage process. In this work, nuclear magnetic resonance (NMR) spectroscopy is developed for the study of the charge storage mechanisms of supercapacitors. Importantly, NMR experiments show that electrolyte ions adsorbed inside the pores of the carbon electrodes can be resolved from those in bulk electrolyte for a range of supercapacitor electrode materials. Chemical shift calculations show that the adsorbed species are subject to ring current effects, whereby the delocalised electrons in the carbon shield the nearby nuclei. The calculated effects depend on the local carbon structure, helping to rationalise the variations observed when different porous carbons are studied experimentally, and allowing structural information to be extracted from the spectra. NMR experiments performed on electrodes extracted from ionic liquid-based supercapacitors with different applied voltages allow the numbers of adsorbed ions to be measured upon charging. It is shown that supercapacitor charging involves the migration of both anions and cations in and out of the carbon pores in each electrode, with the anions dominating the charge storage process. When combined with lineshape measurements, which offer information about the diffusion of adsorbed ions, the power performances of supercapacitor devices with different electrolytes are rationalised. In situ NMR methods are then developed to allow mechanistic studies of working supercapacitors as they are charged and discharged inside the NMR magnet. The experiments reveal that the charge storage mechanism depends on both the electrolyte and the electrode material studied. During charging, reversible chemical shift changes are also observed, arising from the introduction of paratropic ring currents. Finally, cross polarisation experiments allow the selective observation of the adsorbed electrolyte species, and show that their motion slows down during supercapacitor charging. Overall, the NMR approach offers unique insights into the molecular mechanisms of the supercapacitance phenomenon.