The intensity of light produced from synchrotrons enables X-ray imaging down to the micron and submicron scale. This high degree of resolution is necessary to study metals in hydrated biological samples, where trace (metal) elements are found in the lowest concentration. Water within these aqueous samples will undergo radiolysis and produce various reactive oxygen species, which degrades the quality of information gathered from the sample during X-ray imaging. Studies have shown that the best way to counter the effects of radiolysis and preserve samples in their metabolic state during X-ray imaging is to keep them cryogenically frozen. We have developed affordable cryostats and novel protocol to not only improve cryo-imaging at current third-generation synchrotrons, but also enable cryo-imaging at existing synchrotrons that have limited accessibility. This dissertation will provide a detailed description of the tasks that were accomplished to contribute to the development cryo-imaging. The first task was the fabrication of a portable cryostage. The cryostage's discreet profile and unique design successfully enabled it to be effortlessly adapted into three beamlines across two different DOE facilities and facilitate multiple imaging modalities, i.e., correlative imaging. With the next task, we explored adding an ice frame about the stage to help reduce the accumulation of frost on the surface of a frozen sample that was explored. The addition of the ice frame significantly improved the imaging of frozen samples, nearly doubling the overall image clarity in comparison to when it was absent. The final task saw the application of a cryostream, in place of a cryostage, to provide a cooled convective flux across the sample for 2D and 3D visualization for cryo X-ray imaging. / Doctor of Philosophy / Synchrotrons are light producing particle accelerators that enable X-ray imaging down to the micron and submicron scale. This high degree of resolution is necessary to study metals in hydrated biological samples, where trace elements are found in low concentrations. The X-ray beam from the synchrotron will force any water within these aqueous samples to undergo radiation induced water decomposition, i.e., radiolysis, and produce hydroxyl radicals that will degrade the quality of information gathered from the sample during X-ray imaging. Early studies have shown that the best counter to the effects of radiolysis, while also preserving samples in their metabolic state during X-ray imaging, is to keep them cryogenically frozen. We have developed affordable cryostats and novel protocols to not only improve cryo-imaging at current third-generation synchrotrons, but also enable cryo-imaging at existing synchrotrons that have limited accessibility. This dissertation will describe, in detail, three tasks that were accomplished. The first task was to the fabrication of a portable cryostage. The cryostage unique design successfully enabled it to be used within different beamlines and for multiple imaging perspectives. With the next task, an ice frame to help reduce the accumulation of frost on the surface of a frozen sample being explored. The ice frame was shown to significantly improve the imaging of frozen samples. The final task saw the application of a cryostream, a jet stream of cold nitrogen gas, to enable an alternative approach for 2D and 3D visualization for cryo X-ray imaging.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/111590 |
| Date | 22 August 2022 |
| Creators | Lowery, Adam Wallace |
| Contributors | Mechanical Engineering, Boreyko, Jonathan B., Miller, Lisa M., Ben-Tzvi, Pinhas, Paul, Mark R., Huxtable, Scott T. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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