In-Situ Combustion (ISC) is a very complex thermal recovery process that is strongly affected by the chemical composition and physical properties of reservoir rock and fluids. Stability of the process depends on the amount of heat continuously generated from the chemical reactions between fuel formed during ISC and injected oxygen. Heat generation depends on the amount of fuel formed, which, in turn, is affected by initial oil saturation (IOS). Thus, in this study, ISC process dynamics were investigated at various saturations on 7.5 °API Peace River bitumen, under 3.4 l/min air injection rate. Through one-dimensional combustion tube experiments higher combustion front temperatures were observed for increased IOS. The degree of bitumen upgrading was determined in terms of viscosity and API gravity changes. Correlations for hydrogen-carbon ratio, air requirement, consumed fuel, and combustion front velocity were obtained. Good burning characteristics of Peace River bitumen resulted in stable self-sustained combustion with 26.01% IOS. However, an experiment with 13.39% IOS failed because of insufficient fuel generation. Furthermore, X-Ray cross-sectional images were taken along the combustion tube after each run to support and enhance the interpretation of experimental results. Particularly, fluctuations in concentrations of produced gas composition were explained with computed tomography (CT) data.

The jarosite group of minerals is part of the alunite supergroup, which consists of more than 40 different mineral species that have the general formula AB3(TO4)2(OH, H2O)6. There is extensive solid-solution in the A, B and T sites within the alunite supergroup. Jarosite group minerals are common in acid mine waste and there is evidence of jarosite existing on Mars. Members of the jarosite - natrojarosite – hydronium jarosite (K,Na, H3O)Fe3(SO4)2(OH)6 solid-solution series were synthesized and investigated by Rietveld analysis of X-ray powder diffraction data. The synthesized samples have full iron occupancy, where in many previous studies there was significant vacancies in the B site. Well-defined trends can be seen in the unit cell parameters, bond lengths A – O and Fe - O across the solid-solution series in the synthetic samples. Based on unit cell parameters many natural samples appear to have full iron occupancy and correlate well with the synthetic samples from this study. In addition, the infrared spectra of the samples were analyzed. The atomic structure of ammoniojarosite, (NH4)Fe3(SO4)2(OH)6, has been solved using single-crystal X-ray diffraction to wR 3.64% and R 1.4%. The atomic coordinates of the hydrogen atoms of the NH4 group have been located and it was found that the ammonium group has two different orientations with equal probability. Samples in the ammoniojarosite – hydronium jarosite solid-solution series were synthesized and analyzed using powder X-ray diffraction and Rietveld refinement. It was found that an incomplete solid-solution series exists between jarosite and plumbojarosite, Pb[Fe3(SO4)2(OH)6]2, based on experimental and mineralogical data. At the studied synthesis conditions, lead solubility in jarosite is extremely limited with occupancy of 2% in the potassium site. Increased Pb in the iv starting solution resulted in no increased substitution of Pb into jarosite, but an increased substitution of H3O+. The stable isotope (H) geochemistry of hydronium jarosite, (H3O,K)Fe3(SO4)2(O,OH)6, and the effect that the presence of hydronium in the crystal structure has on exchange rates of stable isotope values of jarosite with hydronium substitution has been investigated in this study. / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2008-05-07 18:21:45.136

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No description available.

No description available.

The extracellular matrix (ECM) is a complex of proteins and carbohydrates that not only provides a structural support between tissues but also functions in a wide variety of cellular activities. ECM proteins are large, complex proteins with many repeating domains. Individual domains can be analyzed for the investigation of structure-function relationships. This thesis focuses on two ECM proteins of interest: N-terminal agrin (NtA) and the coiled-coil domain of cartilage oligomeric matrix protein (COMPcc). Agrin is an important ECM protein involved in postsynaptic differentiation at the neuromuscular junction, mediated by binding in the NtA domain. In agrin, the NtA domain is followed by nine follistatin-like (FS) domains. Structural studies showed a novel interdomain disulfide bridge between the NtA and first FS domain in agrin. This disulfide bridge compensates for a seven residue splice insert in the C-terminus of NtA, suggesting that the interdomain disulfide bond may be necessary for the proper folding of agrin. COMP is another important ECM protein that is found in cartilage, tendon, and ligament. It is a homopentamer held together by disulfide bonds in the central coiled-coil oligomerization domain. Previous structural studies demonstrated that COMPcc forms a pentameric α-helical coiled-coil structure containing a 73Å-long cavity with a diameter of 2–6Å that is capable of binding hydrophobic compounds. This binding capacity of COMPcc was investigated and the high-resolution crystal structures of COMPcc in complex with five naturally-occurring fatty acids were solved. Additionally, the binding properties of COMPcc in solution were investigated through the use of fluorescence spectroscopy. Both the x-ray crystallographic and solution data reveal that binding favourability of fatty acids to COMPcc is driven by length of the methylene tail and degree of unsaturation. These results suggest the possibility of COMPcc to be used in targeted drug delivery systems.

The study was conducted to develop a technique that measures the amount of gadolinium based contrast agent accumulated in a head tumour by x-ray fluorescence, while a patient is exposed to neutrons or during external beam radiotherapy planning. In this research, measurements of the gadolinium concentration in a vessel simulating a brain tumour located inside a head phantom, by the x-ray fluorescence method were taken, where the Magnevist contrast medium which has gadolinium atom, in the tumour vessel, was excited by a 36 GBq (0.97 Ci) 241Am source that emits gamma rays of 59.54 keV, in 35.7 % of it’s decays, resulting the emission of characteristic fluorescence of gadolinium at 42.98 keV that appeared in the X-ray fluorescence spectrum. A Cadmium Telluride (CdTe) detector was used to evaluate and make an analysis of the gadolinium concentration. Determinations of the gadolinium content were obtained directly from the detector measurements of XRF from gadolinium in the exposed tumour vessel. The intensity measured by the detector was proportional to the gadolinium concentration in the tumour vessel. These concentrations of gadolinium were evaluated for dose assessment. The positioning of the head phantom was selected to be in the lateral and vertex positions for different sizes of tumour vessels. Spherical tumour vessels of 1.0, 2.0, 3.0 cm and an oval tumour vessel of 2.0 cm diameter and 4.0 cm length, containing the gadolinium agent, contained concentration between 5.62 to 78.63 mg/ml. They were placed at different depths inside a head phantom at different positions in front of the detector and the source for the measurements. These depths ranged from 0.5 cm to 5.5 cm between the center of the tumour and interior wall of the head phantom surface. The total number of measurements in all four sizes of the tumour vessel was 478; 78 examinations of a 1.0 cm spherical tumour vessel, 110 examinations of a 2.0 cm spherical tumour vessel, 150 examinations of a 3.0 cm spherical tumour vessel and 140 examinations of a 2.0 x 4.0 cm ellipsoid tumour vessel. To measure the size and the shape of the tumour by the alternative radiographic method, a general x-ray machine with radiograph film was used. Based on that, the appropriate shape of concentration could be selected for therapy. The differences of optical density in the x-ray films showed that the noise was increased with low concentration of the Gd. Because radiographic film may be subjected to different chemical processes where the darkness will be affected, these measurements would be very hard to be quantitative. Accordingly it is difficult to use the film for Gd concentrations. The obtained data show that the method works very well for such measurements.

This thesis is about the development of the MARS camera: a standalone portable digital x-ray camera with spectral sensitivity. It is built for use in the MARS Spectral system from the Medipix2 and Medipix3 imaging chips. Photon counting detectors and Spectral CT are introduced, and Medipix is identified as a powerful new imaging device. The goals and strategy for the MARS camera are discussed. The Medipix chip physical, electronic and functional aspects, and experience gained, are described. The camera hardware, firmware and supporting PC software are presented. Reports of experimental work on the process of equalisation from noise, and of tests of charge summing mode, conclude the main body of the thesis. The camera has been actively used since late 2009 in pre-clinical research. A list of publications that derive from the use of the camera and the MARS Spectral scanner demonstrates the practical benefits already obtained from this work. Two of the publications are first-author, eight are co-authored, and a further four acknowledge use of the MARS camera as part of the MARS scanner. The work has been presented at three MARS group meetings, two departmental conferences, and at an internal Medipix3 collaboration meeting hosted by ESRF in Grenoble.

Small-animal x-ray imaging is an important tool for medical research. The penetration power of x-rays makes it possible to investigate the 3D structure of small animals and other thick biological samples by computed tomography (CT). However, small-animal x-ray imaging often requires high resolution due to the small structures involved, and short exposure times due to sample movement. This constitutes a challenge, since these two properties require compact x-ray sources with parameters that are not widely available. In this Thesis we present the first application of liquid-metal-jet sources for small-animal imaging. This source concept was invented at KTH just over ten years ago. The use of a high-speed metal jet as electron-beam target, instead of a solid anode, enables higher x-ray flux while maintaining a small x-ray spot for high-resolution imaging. In the present work, a liquid-metal jet source with a higher-energy spectrum has been developed. It has stronger 24 keV radiation compared to previous sources, which makes it more suitable for imaging of small animals and other few-cm-thick objects, which require the higher penetration of 20-35 keV x-rays. We have applied the liquid-metal-jet x-ray sources for whole-body imaging of sacrificed mice and zebrafish. With high-resolution absorption-contrast CT we have visualized fine bone details of mice. We have also used phase contrast, a new method that can considerably improve imaging of, e.g., soft tissue, for demarcation of mm-sized tumors inside a full mouse and for mouse cartilage imaging. In zebrafish imaging, we have exploited the greatly enhanced contrast of phase-imaging to resolve single muscle fibers (and possibly even myofibrils) in whole zebrafish in a laboratory setting for the first time. The muscle structures have diameters in the 5-7 μm range and extremely low contrast, which makes them difficult to observe. With phase contrast, we have demonstrated low-dose and high-resolution angiography of mouse and rat organs and tissues ex vivo. We show detection of blood vessels with diameters below 10 μm with radiation doses compatible with living small animals, which is not possible with absorption contrast and iodinated contrast agents. In addition, we have investigated the vascular network of tumors in mouse ears and visualized the chaotic arrangement of newly-formed blood vessels. Finally, we present the first results from a new high-power liquid-metal-jet x-ray source prototype, operating at 10× the power of our previous sources, with the same x-ray spot size. This source constitutes an important step towards future in-vivo small-animal laboratory imaging with high resolution. / Röntgenavbildning av små försöksdjur är en viktig metod inom medicinsk forskning. Röntgenstrålar penetrerar material, vilket gör det möjligt att undersöka 3D-strukturen hos försöksdjur och andra tjocka biologiska prov med hjälp av datortomografi (CT). Tyvärr kräver smådjursavbildning ofta dels hög upplösning, eftersom de relevanta strukturerna är små, dels korta exponeringstider, eftersom objektet tenderar att röra sig. Detta är en utmaning, då båda egenskaperna kräver kompakta röntgenkällor med speciella egenskaper som inte är brett tillgängliga. I denna avhandling visar vi den första användningen av metallstråleröntgenkällor för avbildning av hela smådjur. Den här typen av röntgenkälla uppfanns vid KTH för drygt tio år sedan. Genom att låta elektronerna träffa en stråle av flytande metall, istället för en solid metallanod, kan vi generera mer röntgenstrålning men samtidigt behålla en liten källpunkt, vilket behövs för avbildning med hög upplösning. En ny metallstrålekälla utvecklades som en del av denna avhandling. Den ger ett röntgenspektrum med högre energier, vilket gör källan mer lämpad än tidigare källor för avbildning av små försöksdjur och andra centimetertjocka biologiska objekt. Vi har använt metallstrålekällor för att avbilda intakta, avlivade möss och zebrafiskar. Med högupplöst absorptions-CT har vi detekterat små bendetaljer inuti möss. Vi har även använt faskontrastavbildning, en ny metod som avsevärt kan förbättra avbildning av mjukvävnad, till att demarkera millimeterstora tumörer inuti en hel mus, samt för avbildning av brosk i leder hos möss. Faskontrast ger en kraftig förstärkning av kontrasten i bilden, vilket även har använts för att för första gången detektera individuella muskelfibrer (och eventuellt även myofibriller) inuti zebrafiskar med en kompakt röntgenkälla. Muskelstrukturerna har diametrar på 5-7 μm och låg kontrast, vilket gör dem svåra att observera. Med hjälp av faskontrast har vi utvecklat en metod för att avbilda blodkärl med diametrar under 10 μm inuti organ och vävnader från möss och råttor ex vivo, med stråldoser som är kompatibla med studier av levande smådjur. Detta är inte möjligt med konventionell absorptionskontrast och jod-baserade kontrastmedel. Vi har dessutom avbildat nyformade blodkärl kring tumörer i musöron och observerat kärlens kaotiska struktur. Slutligen presenterar vi de första resultaten från en prototyp av en ny högeffektskälla. Källan har tio gånger högre effekt än tidigare metallstrålekällor, men bibehåller samma storlek på källpunkten. Den här högeffektskällan är ett viktigt steg mot framtida laboratoriebaserad avbildning av levande små försöksdjur med hög upplösning. / <p>QC 20150331</p>

A complete model of helium-like line and continuum emission in astrophysical plasmas has been incorporated into the plasma simulation code CLOUDY. All elements between He and Zn are treated, any number of levels can be considered, and a full treatment of radiative and collisional processes is included. This includes photoionization from all levels, line transfer including continuum pumping and destruction by background opacities, scattering, and collisional processes. The model is calculated self-consistently with the ionization and thermal structure of the surrounding nebula. The result is a complete line and continuum spectrum of the nebula. The model helium atom is described and compared to a second standalone helium atom in the low-density case. The effects of the mixing of singlet and triplet terms, the truncation of the physical system, and the convergence of the predicted line intensities as a function of the number of quantum levels explicitly included are considered. New Case-B emissivities are calculated for the helium atom at a range of electron temperatures and densities common in planetary nebulae. Observations of the Orion Nebula are analyzed and compared with predictions of the model helium atom. Observations of low-metallicity extragalactic objects by other authors are analyzed. The methods and details of the model helium-like ions are described. The standard X-ray diagnostics of these ions are revisited and augmented with semi-analytical and numerical calculations of ultraviolet line diagnostics. Finally, a new interface between CLOUDY and the X-ray spectral analysis tool XSPEC is discussed.