Atmospheric Chemistry Program Seminar
Update on OFR185 Characterization of the Aerodyne Potential Aerosol Mass Chamber by Jake Rowe,
"One disadvantage of conventional Oxidation Flow Reactors (OFRs) is the difficulty in achieving controlled, shorter (<1 day) oxidative aging processes that are also relevant to atmospheric SOA formation processes. To investigate this issue, this study characterizes two alternative mercury lamp configurations designed to attenuate 185 and/or 254 nm irradiance relative to standard low-pressure UVC mercury lamps used in the Aerodyne Potential Aerosol Mass (PAM) OFR. In the first configuration, the irradiance at 185 and 254 nm was attenuated by applying segments of Viton heat shrink tubing along standard UVC lamps. In another configuration, the 185 nm lamp output was attenuated relative to the 254 nm output by splicing segments of lamp glass that transmit either 185 and 254 nm or only 254 nm radiation. OH exposures attained by photolysis of O2/O3/H2O with these lamps were calculated from the reactive loss of CO and SO2 input to the reactor and measured under steady-state conditions as a function of photon flux and [H2O]. At a midrange relative humidity ~ 50% and τ ~ 2 min, the attainable lower-range photochemical age decreased from ~4-5 to ~0.3-0.4 days of equivalent atmospheric exposure. Thus, the combined usage of attenuated and standard UVC mercury lamps -- as demonstrated here with the PAM OFR -- significantly extends the range of attainable photochemical aging timescales in OFRs with no additional modification of OFR conditions."
Identification and Characterization of a Red Blood Cell Stabilizer by Anna Ziola,
"When creating controls for hematology instruments, the volume of red blood cells (RBCs) must be held constant. Each component in control samples must retain its respective volume throughout the shelf life since the size of the cells is one method of blood component characterization in hematology instruments. The plant extract mixture currently used to stabilize the volume of RBCs is losing its effectiveness, requiring hospitals to purchase and replace these controls more often to ensure accurate patient hematology reports. To identify the active ingredient responsible for RBC stabilization in the plant extract, we used high performance liquid chromatography, mass spectrometry, SDS-PAGE gel electrophoresis, the Sysmex XN-20 and Sysmex XE-5000 to identify and characterize the active ingredient originally responsible for stabilizing the volume of RBCs."