Nitrogenase is a metalloenzyme that plays a key role in biological nitrogen fixation by catalysing the reduction of dinitrogen to ammonia. Study of nitrogenase is particularly challenging because of its unique electron transfer and catalytic components. This Thesis describes the development of a mediated electron transfer system for the MoFe protein of nitrogenase, in order to overcome the complexity of electron transfer by the native reductant Fe protein coupled to hydrolysis of ATP. A series of redox mediators was employed including Eu^III/II-polyaminocarboxylate complexes, which have reduction potentials in a very negative range. In the presence of the redox mediators, the wild type MoFe protein exhibits a catalytic current due to protein-catalysed proton reduction. With this mediated electron transfer method, the potential of proton reduction by nitrogenase was determined for the first time. The redox mediator system was also applied in an infrared (IR) spectroelectrochemical study of CO binding to the wild type and β-98^His variant MoFe protein. The first IR evidence was provided for ATP-independent CO binding to the active site of the MoFe protein, in both the wild type and the variant. The peak wavenumbers and time-dependent changes in intensity found in this study are consistent with the result of previous CO coordination with nitrogenase obtained by electron transfer from the Fe protein driven by ATP. This strongly suggests that this mediated electron transfer approach can deliver low potential electrons into the MoFe protein and reduce the active site FeMoco to the substrate binding level. Moreover, this technique allows electrocatalytic activity of the protein to be monitored and the change in redox activity can be correlated directly to the potential. With the same technique, a study of cyanide binding was performed on different variant MoFe proteins of nitrogenase. The redox properties of the isolated cofactor of Mo- and V-dependent nitrogenase were investigated in parallel to the study of the protein-bound cofactors. It was found that FeVco, the active site from V-nitrogenase, exhibited different redox properties compared to that of Mo-nitrogenase. This might account for the unexpected activity in CO reduction that was reported previously for V-nitrogenase.

Realizamos medidas de transmissão no infravermelho (médio e distante) e espelhamos Raman de amostras de GdAlO3 puras e dopadas com Eu+3 para estudarmos as bandas de absorção de fonons K=0 e as transições eletrônicas nos íons Eu+3. Conhecendo-se a simetria do GdAlO3 (D162h) pudemos, utilizando o método da correlação, calcular o número e a simetria dos modos vibracionais, bem como sua classificação em internos e externos. Os resultados experimentais mostram boa concordância com os teóricos e revelam que o GdAlO3 apresenta três regiões distintas no infravermelho, compostas de várias bandas de absorção. Os modos internos estão em torno de 670cm-1 (estiramento) e 480cm-1 (flexão) enquanto que os modos externos localizam-se em torno de 200cm-1. A interação dos estados eletrônicos do Eu+3 com o campo cristalino do GdAlO3 foi estudada inicialmente supondo um campo de simetria Oh e depois introduzindo a distorção ortorrômbica (Cs) de uma maneira perturbativa. Pudemos verificar que a dita distorção levanta totalmente a degenerescência dos níveis 7FJ (J=0,1,...,6) e torna as transições 7F0 → 7FJ permitidas. / IR and Raman measurements were carried out in pure and Eu+3 - doped GdAlO3 with the purpose of understanding their K=O phonom modes and the Eu+3 electronic transitions. Starting from the GdAlO3 symmetry, (D162h) the correlation method allows the classification of the number and symmetries of the modes, as well their assignment as either internal or external. Experimental and theoretical results are in good agreement and show three well defined absorption bands in GdAlO3. The internal modes are found to be located around 670cm-1 (stretching) and 480cm-1 (bending), while the external modes are around 200cm-1. The interaction of Eu+3 electronic states with the GdAlO3 crystal fields were studied by taking into account small perturbative orthorrombic (Cs) distorcion on a crystal field with symmetry Oh. This small distortion lifts completely the degeneracy of the 7FJ (J=0,1,...,6) levels and allows the 7F0 → 7FJ transitions.

This report is the result of a master thesis made by two students at Linköping University. The aim was to find an image registration method for visual and infrared images and to find an error measure for grading the registration performance. In practice this could be used for position determination by registering the infrared image taken at the current position to a set of visual images with known positions and determining which visual image matches the best. Two methods were tried, using different image feature extractors and different ways to match the features. The first method used phase information in the images to generate soft features and then minimised the square error of the optical flow equation to estimate the transformation between the visual and infrared image. The second method used the Canny edge detector to extract hard features from the images and Chamfer distance as an error measure. Both methods were evaluated for registration as well as position determination and yielded promising results. However, the performance of both methods was image dependent. The soft edge method proved to be more robust and precise and worked better than the hard edge method for both registration and position determination.

This PhD thesis deals with research activity in organic electronics, an extremely exciting field offundamental science, which is complemented by relevant applications in every-day life: optoelectronics,solar energy conversion (photovoltaics), sensing and information technology, just to mentiona few. In this area, charge transfer/energy transfer processes, as well as light matter interaction,play a major role. Within this topic, this work focus on the theoretical study of the electronic structureand related charge transfer/spectroscopic properties of various molecular systems: Coronenecrystals, F4TCNQ/perylene co-crystals, polythiophenes, PCPDT/PCPDT-BT homo- and copolymerbased on thiophene, chemisorbed ferrocene on Si(111) substrate. Particular attention wasdevoted to the calculation of infrared (IR) and electronic spectra associated with the so-called “polaronsignature” in doped organic semiconductors. To assess the reliability and physical meaning of electronic quantities involved in the calculations(like the HOMO/LUMO gap, theoretical spectroscopic intensity and vibrational modes, pursuingthe comparison between neutral and charged systems) a number of different levels of the theoryhave been systematically varied from HF (Hartree-Fock) to “pure” DFT (Density Functional Theory),as well as hybrid B3LYP (Becke 3-Parameter (Exchange), Lee, Yang and Parr 1,2) and longrange corrected Coulomb-Attenuating Method (CAM-B3LYP) functionals. In the attempt to untanglethe physics underlying the polaron formation in charged molecular systems (as evidenced by theoccurrence of giant intensity bands found in IR spectra), the mapping of the vibrational mode betweenneutral and charged systems has been calculated. A major achievement in this work is thatthe vibrational (giant) mode associated with the “polaron” emerges as a new mode (peculiar of thecharged state) not related to any mode existing in the neutral system.

The purpose of this thesis is to compare five different ranking algorithms for query expansion. The algorithms compared are f4, f4mod, porter, wpq, and emim. This is done using a TREC collection, a selection of topics, and relevance judgements. Relative recall is measured before and after the expansion of the query. The study shows that all of the algorithms manage to increase the relative recall, f4 being the one most successful. / Uppsatsnivå: D

The purpose of this investigation was to expand the evaluation of Normal Weight Obesity (NWO) and its association with insulin resistance using a nationally representative sample of U.S. adults. A cross-sectional study including 5,983 subjects was conducted. Body fat percentage was assessed using dual energy X-ray absorptiometry (DXA). Expanded Normal Weight Obesity (eNWO) categories (pairings of BMI and body fat percentage classifications) were determined by standard cut-points for BMI and the gender specific median for body fat percentage. Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) levels were used to index insulin resistance. Mean ± SE values were as follows: BMI: 27.9 ± 0.2 (women) and 27.8 ± 0.1 (men); body fat percentage: 40.5 ± 0.2 (women) and 27.8 ± 0.2 (men); HOMA-IR: 2.04 ± 0.05 (women) 2.47 ± 0.09 (men). HOMA-IR differed systematically and in a dose-response fashion across all levels of the eNWO categories (F = 291.3, P < 0.0001). As BMI levels increased, HOMA-IR increased significantly and within each BMI category, higher levels of body fat were associated significantly with higher levels of HOMA-IR. Both high BMI and high body fat percentage are strongly related to insulin resistance. In this study, insulin resistance increased incrementally according to BMI levels primarily and body fat levels secondarily. Consequently, due to the costs associated with precisely measuring body fat, and the accuracy of using BMI independently, we recommend that BMI be used in its standard form to predict insulin resistance and not be supplemented with an estimate of body fat.

Two-dimensional infrared spectroscopy (2D IR) is a powerful tool to investigate molecular structures and dynamics on femtosecond to picosecond time scales and is applied to diverse systems. Current technologies allow for the acquisition of a single 2D IR spectrum in a few hundreds of milliseconds using a pulse shaper and an array detector, but demanding applications require spectra for many waiting times and involve considerable signal averaging, resulting in data acquisition times that can be many days of laboratory measurement time. Compressive sampling is an emerging signal processing technique to reduce data acquisition time in diverse fields by requiring only a fraction of the traditional number of measurements while yielding much of the same information as the fully-sampled data. Here we combine cutting-edge 2D IR methodology with a novel compressive sampling reconstruction algorithm to reduce the data acquisition time of 2D IR spectroscopy without distorting lineshapes. We introduce the Generic Iteratively Reweighted Annihilating Filter (GIRAF) algorithm re-engineered to the specific problem of 2D IR reconstruction and show its effectiveness applied to various systems, including those with low signal, with multiple peaks, and with differing amounts of frequency shifting. Additionally, we lay the groundwork for 2D IR microscopic imaging using compressive sampling in the spatial image domain. The first instance of a single-pixel camera in the infrared is introduced.

In this thesis a systematic analysis of the correlation effects between lattice dynamics and magnetism in the Multiferroic Manganites RMnO3 with Pnma structure was conducted. For this task, Raman and FT-IR Spectroscopy were employed for an investigation of all optically accessible lattice vibrations, i.e. phonons. To study the correlation effects as well as their specific connections to symmetry and compositional properties of the Multiferroic Manganites, the polarisation and temperature dependence of the phonons were considered explicitly. In combination with lattice dynamical calculations based on Density Functional Theory, two coupling effects - Spin-Phonon Coupling and Electromagnon-Phonon Coupling - were systematically analysed. / Grundlegendes Verständnis der physikalischen Zusammenhänge innerhalb multifunktionaler Materialien im Hinblick auf spätere potentielle Anwendungen ist eines der Hauptziele der heutigen Forschungsbemühungen in der Festkörperphysik. Im Wesentlichen geht es dabei um das Ausnutzen von intrinsischen Kopplungseffekten, um zusätzliche Funktionalität im Vergleich zur heutigen auf Miniaturisierung von halbleiterbasierten Bauelementen aufbauenden Informationstechnologie zu erreichen. Die vorgelegte Dissertation zielt in dies em Themengebiet auf die systematische Untersuchung der Kopplungseffekte zwischen Kristallgitterdynamik und Magnetismus in den multiferroischen Manganaten ab. Konkret geht es um das Modelsystem der multiferroischen Selten-Erd-Manganate RMnO3 mit orthorhombischer Pnma-Struktur. Die zu diesem Zweck verwendeten experimentellen Techniken waren Raman und Fourier-Transform Infrarot (FT-IR) Spektroskopie, mit deren Hilfe alle optisch aktiven Kristallgitterschwingungen dieser Systeme spektroskopiert werden konnten. Zur Untersuchung der Kopplungseffekte wurden die spektroskopischen Experimente polarisationssensitiv und unter Variation der Probentemperatur durchgeführt, um insbesondere Renormalisierungseffekte der Gitterschwingungen im Temperaturbereich magnetischer Phasenübergänge nachweisen zu können. In Verbindung mit gitterdynamischen Rechnungen, die auf der Dichtefunktionaltheorie (DFT) basieren, wurden zwei Kopplungseffekte systematisch untersucht: Spin-Phonon Kopplung (SPC) sowie Elektromagnon-Phonon Kopplung (EMPC).

acase@tulane.edu

Vibrational spectroscopic imaging techniques have emerged as powerful methods of obtaining sensitive spatially resolved molecular information from microscopic samples. The data obtained from such techniques reflect the intrinsic molecular chemistry of the sample and in particular yield a wealth of information regarding functional groups which comprise the majority of important molecules found in cells and tissue. These spectroscopic imaging techniques also have the advantage of acquisition of large numbers of spectral measurements which allow statistical analysis of spectral features which are characteristic of the normal histological state as well as different pathologic disease states. Databases of large numbers of samples can be acquired and used to build model systems that can be used to predict spatial properties of unknown samples. The successful construction and application of such a model system relies on the ability to compile high-quality spectral database information on a large number of samples with minimal sample-to-sample preparation artifact. Tissue microarrays provide a consistent sample preparation for high-throughput infrared spectroscopic profiling of histologic specimens. Tissue arrays consisting of representative normal healthy prostate tissue as well as pathologic entities including prostatitis, benign prostatic hypertrophy, and prostatic adenocarcinoma were constructed and used as sample populations for infrared spectroscopic imaging at high spatial and spectral resolutions. Histological and pathological features of the imaged tissue were correlated with consecutive tissue sections stained with standard histologic stains and visualized via traditional optical microscopy and reviewed with a trained pathologist. Spectral analysis of histologic class mean spectra and subsequent cross-sample statistical validation were used to classify reliable spectral metrics for class discrimination. Multivariate Gaussian maximum likelihood classification algorithms were used to reliably classify all pixels in an image scene to one of six different histologic subclasses: epithelium, smooth muscular stroma, fibrous stroma, corpora amylacea, lymphocytic infiltration, and blood. The developed database-dependent classification methods were used as a tool to investigate subsequent microarrays designed with both normal epithelial tissue as well as adenocarcinoma from a large population of patients. Such investigation led to the identification of spectral features that proved useful in the preliminary discrimination of benign and malignant prostatic epithelial tissue.