Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 279 for “"X-ray fluorescence"”.
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Characterization of soils via portable X-ray fluorescence spectrometer
… and require sample modification. Portable x-ray fluorescence (PXRF) spectrometry is a proximal sensing technique which provides elemental data in-situ, in seconds. This study examined the potential of using PXRF for soil pH and CEC prediction, using a diverse set of soil samples. The use of …
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X-ray fluorescence for quantification of lead and strontium in vivo
… serve as a biomarker of long-term exposure. X-ray fluorescence has been used to measure bone Pb and Sr. However, current systems have limitations with radioisotope sources, bulky equipment, and long measurement times. A portable XRF device capable of measurement of bone Pb and Sr, overcomes the …
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X-Ray Fluorescence Cross Sections for the Elements 55 <= Z <= 60
X-ray cross sections have been found for the elements Cs, Ba, La, Ce, Pr, and Nd. Two methods are used to calculate cross sections which are both compared to theoretical calculations. Comparisons are also made to theoretical relative transition ratios. Finally, cross sections of x-ray transitions …
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Measuring Trace Element Concentrations in Artiodactyl Cannonbones using Portable X-Ray Fluorescence
… faunal analysis technique using portable X-ray fluorescence (pXRF) to measure trace element concentrations in comparative collection and archaeological bone samples. Using cannonbones from five different artiodactyl species, I collected trace element data from 50 comparative collection …
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Single-Cell Measurements of Element Concentration In Phytoplankton Using Synchrotron X-Ray Fluorescence
… in natural particle assemblages. Synchrotron x-ray fluorescence (SXRF) is a microanalytical technique used for the localization and quantification of elemental distributions. This technique enables quantitative and qualitative analysis with high spatial resolution (< 1 µm) and high elemental …
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X-Ray Fluorescence Analysis of Tuscaloosa Marine Shale Cuttings from Horizontally Drilled Wells
… Cretaceous Tuscaloosa Marine Shale (TMS) is a gray to black fissile marine shale deposited at depth of between 10,000 and 20,000 ft near the ancient Gulf of Mexico. The TMS has been gradually developed as a hydrocarbon reservoir in the past several decades. But there are rare researches …
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Composition analysis of high-Tc superconducting thin films by quantitative x-ray fluorescence
… elements Bi, Sr, Br, Cu, and Ca. Quantitative x-ray fluorescence (XRF) consisting of radioactive sources (secondary foil excitor 241Am-Mo source and 55Pe source), a Si(Li) detector, and a multichannel analyzer were employed. The XRF system was calibrated by using sol gel thin films of known …
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Using Portable X-ray Fluorescence to Predict Physical and Chemical Properties of California Soils
… soil sensing technique known as portable X-ray fluorescence spectrometry (pXRF). pXRF analyzers use high energy Xrays that interact with a sample to cause characteristic reflorescence that can be distinguished by the analyzer for its energy and intensity to determine the chemical composition …
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Evaluation of X-ray Fluorescence Spectroscopy as a Tool for Element Analysis in Pea Seeds
X-ray fluorescence spectroscopy (XRF) is a powerful analytical tool for the determination of elemental composition of diverse materials. The principal aim of this study was to evaluate and characterize the utility and reliability of synchrotron-based XRF for use in element analysis of field pea …
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Trace Metal and Speciation Analysis using Ion-Exchange and Energy Dispersive X-ray Fluorescence Spectrometry
… obtained by scanning electron microscopy and x-ray microanalysis showing a homogeneous distribution of functional groups and retained ions on both sectioned and whole resins. Particle size experiments performed on Dowex 50W-X8 (38 - 840 µm) showed that this parameter has no effect on the …
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Characterization of Cu-rich aggregates in neurogenic niches of the rodent brain by X-ray fluorescence microscopy
… has historically been challenging. X-ray fluorescence microscopy (XRF) offers excellent spatial resolution (down to 30~nm) and detection limits (sub parts per million), making it an excellent tool for analyzing metal distributions in the brain. Using XRF, it is demonstrated that …
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Tetrasulphonated phthalocyanine thin films deposited on gold electrodes : a study using voltammetry and synchrotron micro X-ray fluorescence
Het doel van dit werk was de studie van de modificatie van goudelektroden met kobalt(II)tetrasulfoftalocyanine (CoTSPc) en 3,4’,4’’,4’’’ koper(II)-tetrasulfoftalocyanine in een pH 12 bufferoplossing. Een beter begrip van de karakteristieken van de ftalocyaninelagen op de elektrode maakt immers de …
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Development and validation of a theoretical model for optimizing signal-to-noise ratio in x-ray fluorescence imaging
There has been a growing interest in benchtop X-ray Fluorescence Computed Tomography (XFCT) due to its potential to non-invasively image non-radioactive targets at greater depths than optical techniques. However, this modality suffers from limited sensitivity due to the high scattering background …
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X-Ray Fluorescence Analysis Of The Bakken And Three Forks Formations Of The Williston Basin, North Dakota And Well Logging Applications
… of the Williston Basin in North Dakota using x-ray fluorescence. The Charlotte 1-22H core sequence from Continental Resources was also included to assess the elemental composition of the stratigraphic interval spanning the Lodgepole, Bakken, Pronghorn, and Three Forks Formations. Core samples …
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A feasibility evaluation of x-ray fluorescence emission tomography and x-ray luminescence tomography for real-time assessment of photodynamic therapy
… Therapy (PDT) has found use in a wide-array of clinical applications such as in cancer and acne treatment. Photodynamic therapy, uses a photosensitive compound activated by a specific wavelength photon to produce cytotoxic oxygen species (either in free radical form or in singlet form). …
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A tri-modality x-ray fluorescence, x-ray luminescence, x-ray transmission computed tomography imaging platform for monitoring and stimulating metal-containing nanoparticles
X-ray-activated photodynamic therapy (X-PDT) techniques have gained traction for its potential to impart therapeutic effects at greater depths than possible with traditional photodynamic therapy [1], [2]. Interestingly, the underlying X-PDT process could also generate X-ray fluorescence (XF) with …
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A low dilution fusion technique for the determination of major, minor and trace elements in Lamproite and Kimberlite samples by X-ray fluorescence spectrometry
… of major, minor and trace elements by x-ray fluorescence spectrometry (XRFS). This method has been used to analyze geological samples of widely varying and unusual composition such as lamproites and kimberlites. The results are shown to be of comparable if not better accuracy than other …
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