Browsing by Author "Johnson, Alexander"

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    Comprehensive Multidimensional Separations of Biological Samples using Capillary Electrophoresis coupled with Micro Free Flow Electrophoresis
    (2017-12) Johnson, Alexander
    Micro free-flow electrophoresis (μFFE) is a continuous separation technique in which analytes are streamed through a perpendicularly applied electric field in a planar separation channel. Analyte streams are deflected laterally based on their electrophoretic mobilities as they flow through the separation channel. The continuous nature of µFFE separations makes it uniquely suitable as the second dimension for multidimensional separations. The focus of this work is the development of coupling capillary electrophoresis (CE) to µFFE as a high speed two-dimensional (2D) separation platform, followed by an investigation of orthogonality of the two techniques, and finally a novel label-free detection method for µFFE separations. A new µFFE device was fabricated and coupled to CE via capillary inserted directly into the µFFE separation channel. High peak capacity separations of trypsin digested BSA and small molecule bioamines demonstrated the power of CE × µFFE. Since both methods rely on electrophoretic mobility to separate, an investigation on the orthogonality of the two techniques was carried out. µFFE can operate in many different separation modes to increase the orthogonality CE × µFFE. Lastly, fluorescent labeling of the analytes can cause the sample to lose its dimensionality affecting 2D separation peak capacity and coverage. A novel absorption detector was studied to demonstrate the first ever label free absorption detection on a µFFE device. A separation was performed on visible dyes and their detection limits quantified.
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    Qualitative Assessment of Vulnerability to Climate Change
    (2020-05) Allen, Martha; Dixon, Nicola; Fleming, John; Johnson, Alexander; Melcher, TJ
    The Minnesota Department of Transportation (MnDOT) is completing an ongoing assessment to improve its understanding of the vulnerability of state-owned infrastructure to climate change and changing precipitation patterns. Modelling and data-related assessments are currently under development that will identify vulnerabilities and will allow MnDOT to improve future planning and maintenance strategies. To supplement these quantitative methods, MnDOT sought to collect insight and perspectives from field personnel. MnDOT’s Office of Sustainability and Public Health (OSPH) recruited a graduate team from the Hubert H. Humphrey School of Public Affairs at the University of Minnesota to complete this assessment in four steps: 1. Conduct background research on relevant case studies 2. Develop a replicable approach to collect field personnel perspectives 3. Pilot this outreach approach in a single district and analyze results 4. Provide recommendations for future iterations in other districts