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  • 1
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Proteins ; Peptides ; Derivatized polystyrene nanoparticles ; Coated capillary ; Hydrophilic surface ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: High-resolution capillary electrophoretic separation of proteins and peptides was achieved by coating the inner wall of 75 μm ID fused-silica capillaries with 40-140 nm polystyrene particles which have been derivatized with α-ω-diamines such as ethylenediamine or 1, 10-diaminodecane. A stable and irreversibly adsorbed coating was obtained upon deprotonation of the capillary surface with aqueous sodium hydroxide and subsequent flushing with a suspension of the positively charged particles. At pH 3.1, the detrimental adsorption of proteins to the capillary inner wall was suppressed efficiently because of electrostatic repulsion of the positively charged proteins from the positively charged coating which enabled protein separations with maximum efficiencies of 400 000 plates per meter. A substantial improvement of separation efficiency in particle-coated capillaries was observed after in-column derivatization of amino functionalities with 2,3-epoxy-1-propanol, resulting in a more hydrophilic coating. Five basic and four acidic proteins could be separated in less than 7 min with efficiencies up to 1 900 000 theoretical plates per meter. Finally, coated capillaries were applied to the high-resolution analysis of protein glycoforms and bioactive peptides.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-07-13
    Description: A fan tone noise prediction code has been developed at NASA Glenn Research Center that is capable of estimating duct mode sound power levels for a fan ingesting distorted inflow. This code was used to predict the circumferential and radial mode sound power levels in the inlet and exhaust duct of an axial spacecraft cabin ventilation fan. Noise predictions at fan design rotational speed were generated. Three fan inflow conditions were studied: an undistorted inflow, a circumferentially symmetric inflow distortion pattern (cylindrical rods inserted radially into the flowpath at 15deg, 135deg, and 255deg), and a circumferentially asymmetric inflow distortion pattern (rods located at 15deg, 52deg and 173deg). Noise predictions indicate that tones are produced for the distorted inflow cases that are not present when the fan operates with an undistorted inflow. Experimental data are needed to validate these acoustic predictions, as well as the aerodynamic performance predictions. Given the aerodynamic design of the spacecraft cabin ventilation fan, a mechanical and electrical conceptual design study was conducted. Design features of a fan suitable for obtaining detailed acoustic and aerodynamic measurements needed to validate predictions are discussed.
    Keywords: Aerodynamics
    Type: NASA/TM-2012-217681 , E-18071-2 , Noise-Con 2011; Jul 25, 2011 - Jul 27, 2011; Portland, OR; United States
    Format: application/pdf
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