Browsing by Author "Klein, David M. (TTU)"
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Item Bioaccessibility of antimony and other trace elements from lead shot pellets in a simulated avian gizzard environment(2020) French, Amanda D. (TTU); Shaw, Katherine (TTU); Barnes, Melanie (TTU); Cañas-Carrell, Jaclyn E. (TTU); Conway, Warren C. (TTU); Klein, David M. (TTU)Many studies have used grit (in the form of lead (Pb) pellets) presence in avian gizzards as an indicator of Pb shot exposure. However, due to nearly complete pellet absorption in gizzards or rapid passage of pellets, the absence of Pb shot presence in a gizzard does not confirm lack of Pb shot exposure. This study provides the basis for an additional technique to identify if elevated tissue Pb concentration is due to Pb shot exposure. Bioaccessibility of Pb and trace elements (Sb, As, and Sn) present in Pb shot were quantified to determine if any of these elements would be useful as a secondary marker of Pb shot exposure. An avian physiologically based extraction test (PBET) was used to determine pellet dissolution rate and bioaccessible concentrations of Pb, Sb, As, and Sn in a simulated gizzard environment. Of the three trace elements, only Sb concentrations (44–302 μg/mL) extracted into the gizzard solution were greater than environmental background levels (US soil average 0.48 μg/g); thus, no natural source likely provides this amount of Sb. Therefore, there is evidence that Sb can be extracted from Pb shot in bird gizzards at detectable concentrations (above natural background). While further studies are needed to delineate the mechanisms of absorption and distribution, this study lends credence to the hypothesis that Sb may be a useful marker of Pb shot exposure in biological tissues, particularly when Pb pellets are not present nor observed in avian tissues.Item Kinetic molecular theory of sound exposure in personal listening devices(2017) Oates, R. P. (TTU); Ambrose, Stephen; Klein, David M. (TTU)Noise-induced hearing loss associated with earbud use is an increasing trend in modern society. All smartphones are coupled with earbuds that expose the human auditory system to unsafe sound pressures. Acoustic waves enclosed in the ear canal force the tympanic membrane to move 100-1000 times greater than acoustic waves of equal amplitude in open air. Classical acoustics has not fully explained this biophysical phenomenon. Maxwell's kinetic molecular theory was used, in conjunction with Special relativity, to quantify sound pressure exposures in personal listening devices more accurately. A non-linear dependence of sound intensity on speaker excursion is predicted, demonstrating that earbuds sealed in the ear canal can exceed the National Institute for Occupational Safety and Health's ceiling limit of 140 dB. Sound intensities predicted from molecular mass and velocity produce similar results to Beranek's model of acoustic waves in a closed, rigid cylinder and support previous observations of trapped volume insertion gain in personal listening devices.