Browsing by Subject "Separation"
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Item Between us an invisible column(2014-05) LaDeau, Philip Ross; Williams, Jeff, M.F.A.This report chronicles the processes and influences relevant to my work as it has developed over the past three years. I examine how our human separateness and new technologies have effected myself and the work I create, ultimately exploring how technology has aggravated this separation rather than mitigate it. I explain my appropriation of digital, repetitious, and machine-like processes in order to recreate this separation, primarily in the form of drawings, sculptures, and photographs.Item Daters' reactions to geographic separation : do biological sex and interderpence type predict missing and coping?(2007-05) Crockett, Erin Earle, 1983-; Loving, Timothy J.How daters react to being separated from their romantic partners was investigated. Specifically, biological sex and a correlate of biological sex, interdependence type, were tested as predictors of the extent to which individuals (a) miss their partners and (b) use specific strategies in an attempt to cope with the separation. Three online assessments of missing and coping were administered to students (N=124) over winter break while they were separated from their dating partners. Although biological sex was limited in its ability to predict missing and coping, interdependence type consistently predicted how individuals experienced and coped with geographic separation.Item Fundamental study of hydrophobic microporous membrane contactors for the recovery of insoluble oil from oil-water mixtures(2016-05) Mercelat, Aurore Yvonne Joelle; Katz, Lynn Ellen; Seibert, Frank; Kinney, Kerry A.; Lawler, Desmond F; Freeman, Benny DInsoluble oil and water mixtures occur in many industries such as food, metallurgical, or biofuel production. In particular, as we strive to meet global energy demands, the associated risks and waste management of the oil and gas industry must be addressed. Technologies capable of separating oil and water efficiently are needed for the treatment of highly variable oil and gas streams such as produced and flowback waters or oil spills. The goal of this doctoral work was to advance the understanding of a membrane contactor process for the recovery of insoluble oil from water. The hydrophobic hollow fiber membrane had been successfully tested in our laboratories for oil recovery from algae slurries. However, a thorough study to understand the fundamental mechanisms of the separation process was necessary for engineering design and process optimization. First, pure oil experiments were performed to define baseline performance attainable with the studied membrane contactors. Then, oil-water separation experiments were conducted to quantify the effect of key operating parameters. Two relevant ranges of oil feed concentration were identified. For high oil feed concentration, increases in transmembrane pressure and influent flow rate were confirmed to increase oil flux, while higher viscosity lowered oil permeation across the fiber walls. However, an important finding was that, for dilute mixtures, decreases in transmembrane pressure and higher viscosity increased oil permeation. The results of this research support the conclusion that oil separation within the particular geometry and design of the membrane contactor is due to both internal coalescence of oil droplets and selective permeation of oil over water. The stability of an oil film on the fibers was critical to enhance effective surface area of the membrane contactor. In addition, the technology showed great promise for long-term high oil removal with no signs of viscous fouling as often observed in hydrophilic membranes. Finally, a model describing the process was developed and can be used as a guideline for membrane sizing and process engineering design.Item Micro/nano-patterning of supported lipid bilayers: biophysical studies and membrane-associated species separation(2009-05-15) Shi, JinjunMicro/nano-patterning of supported lipid bilayers (SLBs) has shown considerable potential for addressing fundamental biophysical questions about cell membrane behavior and the creation of a new generation of biosensors. Herein are presented several novel lithographic methods for the size-controlled patterning of SLBs from the microscale to the nanoscale. Using these methods, chemically distinct types of phospholipid bilayers and/or Escherichia Coli (E. Coli) membranes can be spatially addressed on a single microchip. These arrays can, in turn, be employed in the studies of multivalent ligand-receptor interactions, enzyme kinetics, SLBs size limitation, and membrane-associated species separation. The investigations performed in the Laboratory for Biological Surface Science include the following projects. Chapters II and III describe the creation of lab-on-a-chip based platforms by patterning SLBs in microfluidic devices, which were employed in high throughput binding assays for multivalent ligand-receptor interactions between cholera toxin B subunits (CTB) and ganglioside GM1. The studies on the effect of ligand density for multivalent CTB-GM1 interactions revealed that the CTB-GM1 binding weakened with increasing GM1 density. Such a result can be explained by the clustering of GM1 on the supported phospholipid membranes, which in turn inhibits the binding of CTB. Chapter IV characterizes the enzymatic activity of phosphatase tethered to SLBs in a microfluidic device. Higher turnover rate and catalytic efficiency were observed at low enzyme surface densities, ascribing to the low steric crowding hindrance and high enzyme fluidity, as well as the resulting improvement of substrate accessibility and affinity of enzyme catalytic sites. Chapter V presents sub-100 nm patterning of supported biomembranes by atomic force microscopy (AFM) based nanoshaving lithography. Stable SLBs formed by this method have a lower size limit of ~ 55 nm in width. This size limit stems from a balance between a favorable bilayer adhesion energy and an unfavorable bilayer edge energy. Finally, chapter VI demonstrates the electrophoretic separation of membrane-associated fluorophores in polymer-cushioned lipid bilayers. This electrophoretic method was applied to the separation of membrane proteins in E. Coli ghost membranes.Item Novel devices for analytical-scale isoelectric trapping separations(2009-05-15) Lim, Peniel JasonIsoelectric trapping (IET), has proven to be one of the most successful electrophoretic techniques used for separations of ampholytic compounds. IET is carried out in multicompartment electrolyzers (MCEs) in which adjacent compartments are joined through buffering membranes whose pH values bracket the pI of the ampholytic component to be trapped in the compartment. The present small-scale instruments use plastics as their structural materials, which causes poor Joule heat dissipation. The separation compartments have cylindrical or pear-shaped interiors with large internal diameters, which create long heat transfer paths. The long electrode distances yield low field strengths that lead to low electrophoretic velocities for the analytes. These factors interrelatedly limit the electric power that can be applied to the system, contributing to long separation times. Furthermore, these devices do not offer a realistic solution to the problems associated with the detection of low abundance proteins. To address these problems, two novel IET devices have been developed for small-scale IET separations. The first device, named MSWIFT, was constructed using thermally conductive, high-purity alumina as the structural material of the separation compartments. By creating narrow, 0.1- or 0.2-mL channels in thin alumina blocks, the heat transfer path from the center of the compartment to the wall was significantly decreased; and the distance between electrodes was greatly shortened. MSWIFT achieved 6 to 50 times faster IET separations compared to other MCEs. The second device, named ConFrac, was developed to simultaneously fractionate and concentrate ampholytic components from a complex sample into 0.1-mL collection compartments. By designing a system with a 2-dimensional pH gradient and allowing recirculation of the sample feed, the ConFrac demonstrated enrichment of analytes by a factor of 100 and greater.