In this thesis, two aspects of research in soft X-ray absorption spectroscopy chemistry are explored. The first objective was to measure the natural circular dichroism of small chiral organic molecules at soft X-ray wavelengths. The second objective was to characterize the electronic structure and spectra of a series of organometallic polymers. <p>The goal of the first part of this thesis was to enhance the sensitivity of Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy to the intrinsic handedness of chiral organic molecules. The phenomenon of X-ray natural circular dichroism (XNCD) has been well described by theoreticians; however, there have been few successful measurements reported, mainly due to the weakness of the effect and the difficulty of preparing suitable samples. The fourth chapter of this thesis outlines the requirements for XNCD experiments and the efforts made to prepare appropriate samples. <p>The goal of the second part was to use NEXAFS spectroscopy as an analytical technique for the elemental and chemical characterization of innovative materials based on organoiron compounds. The interpretation of transition metal compounds by NEXAFS spectroscopy is difficult due to complex interactions between the metal and its surroundings. Two approaches are commonly used; an atomic multiplet model and a covalent bonding model, which lead to conflicting spectral assignments. Earlier NEXAFS studies of metallocene complexes were found to be lacking as these two models were not adequately rationalized. Owing in part to greatly improved instrumental sensitivity and to efficient theoretical calculations, the interpretation of NEXAFS spectra for a series of metallocene and metal arene complexes was refined. Enhanced understanding of the spectroscopy of these compounds eventually contributed to the characterization of a series of organometallic polymeric materials.<p>Underlining these studies is the remarkable complementarity of NEXAFS spectroscopy and chemistry. A comprehensive understanding of the chemistry of the samples examined in the measurement of XNCD is shown to be crucial for a successful advancement of this spectroscopy. In return, optimization of soft X-ray spectroscopy of metallocenes is demonstrated to remarkably benefit the understanding of the organometallic polymers.

Living organisms constantly respond to changing environmental conditions, and some changes can be far from optimal for many organisms. Insects represent the majority of species in many ecosystems and play an important role in bioaccumulation and biotransformation of environmental contaminants such as selenium and arsenic. Some insectivorous predators feeding on these insects are highly sensitive to such elements resulting in reduced growth, reproductive failures and low population numbers. The mechanisms of selenium and arsenic uptake through the food chain are poorly understood. The determination of chemical speciation is a prerequisite for a mechanistic understanding of a contaminants bioavailability and toxicity to an organism. Synchrotron-based X-ray absorption spectroscopy was used to identify the chemical form of selenium and arsenic in insects in both the field and laboratory conditions. Insects living in streams near Hinton, Alberta affected by coal mine activities were examined for selenium speciation. Results showed higher percentages of inorganic selenium in primary consumers, detritivores and filter feeders than in predatory insects. Selenides and diselenides constitute a major fraction of selenium in these insects. In another field setting, speciation of selenium was studied in insects attacking selenium hyperaccumulating plant <i>Astragalus bisulcatus</i>. The effect of selenate and arsenate alone and the combined effects of selenate and arsenate on insects and parasitoids were monitored using a laboratory-reared moth (<i>Mamestra configurata</i>). Hosts receiving selenium biotransformed selenate to organic selenides and diselenides, which were transferred to the parasitoids in the third trophic level. Arsenic fed larvae biotransformed dietary arsenate to yield predominantly trivalent arsenic coordinated with three aliphatic sulfurs. Larvae receiving arsenate used a novel six-coordinated arsenic form as an excretory molecule in fecal matter and cast skin. X-ray absorption spectroscopy imaging with micro X-ray fluorescence imaging on selenate and arsenate fed larvae revealed highly localized selenium and arsenic species, zinc and copper within the gut. The results provide insights into how the insects cope with their toxic cargo, including how selenium and arsenic are biotransformed into other chemical forms and how they can be eliminated from the insects. The implication of selenium and arsenic species in the diet of predators and detritivores is discussed.

Alginate is a popular biomaterial in tissue engineering. When crosslinked with calcium ions (Ca2+), alginate forms a hydrogel which provides necessary mechanical support as a scaffold. The material properties as well as the biological properties of alginate scaffold are of great importance. In this thesis, the aim is to use traditional methods, such as scanning electron microscopy (SEM) and light microscopy, and emerging X-ray imaging techniques, such as micro-computed tomography (micro-CT) and synchrotron radiation (SR) X-ray imaging, to characterize the alginate scaffolds. Firstly, the material properties of freeze-dried alginate scaffolds were evaluated using micro-CT, as it is a non-destructive and non-invasive imaging method, and can provide three-dimensional information. Alginate scaffolds made with different sodium alginate concentrations and frozen to different temperatures were scanned and analyzed in micro-CT. Results indicated that lower freezing temperature and higher sodium alginate concentration lead to smaller pore size and porosity. Secondly, cell culture experiments were carried out to study the biological properties and the interactions of alginate hydrogel with cells. A Schwann cell line was either blended with alginate solution before crosslinking with calcium chloride (CaCl2) or put around alginate gel in the culture dish. Light microscopy of sectioned slices showed that cells surrounding the alginate gel could not grow into the gel, while cells blended with alginate solution before crosslinking could proliferate inside the hydrogel. Cells grown inside a thin slice of alginate gels appeared to be in better condition and were larger in size and also grew in clusters. Thirdly, in order to image soft tissue buried inside alginate gels, such as brain slices, novel imaging methods based on synchrotron radiation (SR) were applied, such as absorption and phase contrast imaging, diffraction-enhanced imaging (DEI) and also combined with computed tomography (CT). Synchrotron-based monochromatic X-ray imaging proved to be good at distinguish objects of similar density, especially biological soft tissue samples, even without any staining material, such as osmium tetroxide (OsO4). These three pieces of research work show the potential in applying the emerging X-ray imaging in soft tissue engineering.

There are a significant number of microwave applications, where improvement of such qualities as manufacturing costs, size, weight, power consumption, etc. have attracted much research interest. In order to meet these requirements, new technologies can be actively involved in fabrication of microwave components with improved characteristics. One such fabrication technology is called LIGA (a German acronym with an English translation of lithography, electroforming, and moulding) that allows fabrication of high aspect ratio (tall) structures, and only recently is receiving growing attention in microwave component fabrication.<p> The characteristics of high aspect ratio microstrip and coplanar waveguide (CPW) transmission lines are investigated in this thesis. Very low impedance high aspect ratio CPW transmission lines can be realized. A high aspect ratio microstrip folded half wavelength open loop resonator is introduced. Effective configurations for external and bypass gap coupling with open loop resonators are given. Filters with transmission zeros in the stopband, consisting of high aspect ratio single mode open loop resonators are presented to demonstrate the advantages of high aspect ratio structures in realizing lower external quality factors or tight coupling. The transmission zeros are created by novel coupling routings. Some of the filters are fabricated and the filter responses are measured to validate high aspect ratio coupling structures. High aspect ratio diplexers with increased channel isolation are also designed by appropriately combining filters with transmission zeros.<p> A wideband bandpass filter design method, based on the electromagnetic bandgap (EBG) concept is introduced in this thesis. The wideband filters are miniaturized as a result of using the EBG concept in design. An EBG based wideband filter consisting of unit cells that are realized by using high aspect ratio CPW stepped impedance resonators is also presented. The main advantage of this approach is that the high aspect ratio CPW structures make short unit cells practically realizable, resulting in compact filter structure.

For high-resolution X-ray imaging scintillator applications, we have prepared and optically characterized divalent samarium doped fluorochlorozirconate (FCZ:Sm2+) glasses and glass-ceramics. Sm2+ doped FCZ glasses were obtained by adding a reducing agent, NaBH4 into the initial melt to convert some of the Sm3+ to Sm2+. However, the Sm2+ concentration at most was estimated to be only approximately 0.003 %. The as-prepared glass samples were further heat treated to obtain glass-ceramics; the nucleation and growth of BaCl2 nanocrystals were confirmed by powdered X-ray diffraction (XRD) experiments. Depending on the heat treatment conditions (temperature and time), the average nanocrystal size varies from 8 to 170 nm, and the sample contains BaCl2 nanocrystals with the orthorhombic and/or hexagonal structure. The optical absorption spectra for our glass-ceramic samples suggested the substitution of Sm2+ ions into the BaCl2 lattice site. The FCZ:Sm2+ glass-ceramics samples showed strong fluorescence in the red region of spectrum (approximately 8 times that of an as-prepared glass), and the transparency can be very high (transmittance > 80 % for samples with thickness about 0.5 mm) and can be equivalent to that of an as-prepared glass . These two results promise potential as a high-resolution X-ray scintillator due to the emission wavelength range and high transparency. Extensive studies of photoluminescence (PL) spectra at low temperatures (12 -- 200 K) for FCZ:Sm2+ glass-ceramics suggested useful indicators of the crystal structure and average size of embedded BaCl2 nanocrystals. A detailed analysis of the optical spectra has lead to the identification of the origin of the emission peaks and the location of Sm ions at specific crystallographic sites. X-ray induced luminescence (XL) studies have suggested a strong dependence of the fluorescence intensity on the concentration of Sm2+ ions. In addition, for more efficient fluorescence, a sample should be heat treated in a hydrogen containing atmosphere (e.g. H2 + Ar gas), and the heat treatment conditions should be such that the nanocrystals grow in the hexagonal structure.

This Bachelor paper deals with skeletal diseases like osteoporosis and osteoarthritis. 24 medieval individuals from the block Banken 1 in Visby, Gotland were chosen for an osteological analysis. Osteoporosis affects the bone with low bone mineral density and can lead to possible fractures and Osteoarthritis is a degenerative joint disease. A DEXA reading was done at Dr. Roland Alvarssons Doctorial practice in Visby and the results from the DEXA reading showed that none of the individuals suffered from osteoporosis, but one suffered from osteopenia. Some individuals were x-rayed at Visby hospital and the x-rays were interpreted by Dr. Staffan Jennerholm. The x-ray showed that two individuals suffered from osteoarthritis. You can get a glint into the past and daily life of medieval people with a little help of modern technology like x-ray and DEXA reading.

In this work, two innovations were demonstrated for in-situ 3D study of fatigue cracks and their closure as a function of applied load. The first related to improvements in how absorption microtomography is used to study fatigue cracks. The second is a new approach to 3D crack mapping relying on X-ray phase imaging and stereometric approaches. Absorption microtomography was used to determine crack surface positions. Crack opening was measured from absorption microtomography data both before and after crack extension and patterns of opening at several loads were analyzed for both cases. X-ray phase contrast imaging, an alternative approach to absorption microtomography, whose sensitivity to cracks is not strongly affected by the shape of the specimen, was also investigated. Increased sensitivity of phase imaging to cracks, compared to that of the absorption X-ray methods, allowed detecting crack positions up to the crack tip with no load applied to the sample. Stereometry reconstruction based on the phase microradiographs was carried out, and the results were compared with those of absorption microtomography on the same specimen. This study demonstrated that it is possible to reconstruct accurate 3D positions of features inside optically opaque sample by recording several X-ray phase microradiographs.

Monte Carlo (MC) methods are widely accepted as the most accurate technique for calculating dose distributions in radiation therapy physics. Simulating the particle transport through the treatment head of a linear accelerator utilizing a MC based code is both a widespread and practical approach to determining detailed clinical beam characteristics such as the energy, angular and spatial distribution of particles which are needed to properly quantify dose. One particular and versatile MC code, the Monte Carlo N-Particle (MCNP) radiation transport code, developed by Los Alamos National Laboratory, has been commonly used to model ionizing radiations for medical physics applications. In this thesis, a Varian 2100C linear accelerator (linac) is modeled and the electron and photon transport through the primary components of the treatment head are simulated using MCNP Version 5_1.3. The 6 MV photon spectra was characterized in a standard 10 x 10 cm2 field and subsequent dose calculations were made in a Virtual Water (VW) phantom. Energy fluence, percent depth dose and beam profile measurements were taken in a modeled VW phantom and the calculated data was compared to measured reference data. In addition, a human phantom was modeled for future dose calculations using the modeled linac. The linac model created can incorporate different beam energies for determining the dose distribution of multiple beam treatments in phantoms for standard 6 MV plans. The adaptability of this MCNP model allows for any number of geometries and sources encountered in medical physics to be computed and applied with relative ease. Future studies can involve adding complex multi-leaf collimator beam shaping and calculating the dose in human phantom models, which would serve as a basis for studies involving MCNP modeling for dose optimization in medical physics applications.

As technological advances occur, many conventional materials are incapable of providing the unique multi-functional characteristics demanded thus driving an accelerated focus to create new material systems such as carbon and graphite foams. The improvement of their mechanical stiffness and strength, and tailoring of thermal and electrical conductivities are two areas of multi-functionality with active interest and investment by researchers. The present research focuses on developing models to facilitate and assess multi-functional carbon foams in an effort to expand knowledge. The foundation of the models relies on a unique approach to finite element meshing which captures the morphology of carbon foams. The developed models also include ligament anisotropy and coatings to provide comprehensive information to guide processing researchers in their pursuit of tailorable performance. Several illustrations are undertaken at multiple scales to explore the response of multi-functional carbon foams under coupled field environments providing valuable insight for design engineers in emerging technologies. The illustrations highlight the importance of individual moduli in the anisotropic stiffness matrix as well as the impact of common processing defects when tailoring the bulk stiffness. Furthermore, complete coating coverage and quality interface conditions are critical when utilizing copper to improve thermal and electrical conductivity of carbon foams.

The quantification of plutonium (Pu) in spent nuclear fuel is an increasingly important safeguards issue. There exists an estimated worldwide 980 metric tons of Pu in the nuclear fuel cycle and the majority is in spent nuclear fuel waiting for long term storage or fuel reprocessing. This study investigates utilizing the measurement of x-ray fluorescence (XRF) from the spent fuel for the quantification of its uranium (U) to Pu ratio. Pu quantification measurements at the front end of the reprocessing plant, the fuel cycle area of interest, would improve input accountability and shipper/receiver differences. XRF measurements were made on individual PWR fuel rods with varying fuel ages and final burn-ups at Oak Ridge National Laboratory (ORNL) in July 2008 and January 2009. These measurements successfully showed that it is possible to measure the Pu x-ray peak at 103.7 keV in PWR spent fuel (~1 percent Pu) using a planar HPGe detector. Prior to these measurement campaigns, the Pu peak has only been measured for fast breeder reactor fuel (~40 percent Pu). To understand the physics of the measurements, several modern physics simulations were conducted to determine the fuel isotopics, the sources of XRF in the spent fuel, and the sources of Compton continuum. Fuel transformation and decay simulations demonstrated the Pu/U measured peak ratio is directly proportional to the Pu/U content and increases linearly as burn-up increases. Spent fuel source simulations showed for 4 to 13 year old PWR fuel with burn-up ranges from 50 to 67 GWd/MTU, initial photon sources and resulting Compton and XRF interactions adequately model the spent fuel measured spectrum and background. The detector simulations also showed the contributions to the Compton continuum from strongest to weakest are as follows: the fuel, the shipping tube, the cladding, the detector can, the detector crystal and the collimator end. The detector simulations showed the relationship between the Pu/U peak ratio and fuel burn-up over predict the measured Pu/U peak but the trend is the same. In conclusion, the spent fuel simulations using modern radiation transport physics codes can model the actual spent fuel measurements but need to be benchmarked.