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Inverse Problems in Radiative Transfer
Published in John R. Howell, M. Pinar Mengüç, Kyle Daun, Robert Siegel, Thermal Radiation Heat Transfer, 2020
John R. Howell, M. Pinar Mengüç, Kyle Daun, Robert Siegel
Light-scattering is frequently used to measure the size distribution of droplets and aerosolized particles. A typical scenario is shown in Example 18.1. In most experiments a beam of light (e.g., a laser or sunlight) shines through a suspension of droplets or particles, and the scattered light is measured over a given set of angles. For a dispersion of uniform particles, the angular intensity can be calculated from the differential scattering cross-section of the particles (Van de Hülst 1957, Bohren and Huffman 1983), but in the case of a polydisperse distribution, the scattered light is due to the superposition of all types of particles. Consequently, the measured data is related to the unknown size distribution by a Fredholm IFK, and the ill-posedness depends on the blending action of the light-scattering kernel.
Rodent Inhalation Studies in Nanomaterial Risk Assessment
Published in Bertrand Henri Rihn, Biomedical Application of Nanoparticles, 2017
Laurent Gaté, Frédéric Cosnier, Flemming R. Cassee
Aerosol is produced from a nanostructured powder which is aerosolized by a combination of mechanical forces and air carriers (Table 7.1 and Figure 7.1). Available dispersion techniques include rotating brush generator, Wright dust feeder, small-scale powder disperser, jet mill, fluidized bed aerosol generator, and acoustical-based computer controlled system (Figure 7.2b). These devices, which are often easy-to-use and inexpensive, allow the dispersion of (nano) materials without prior treatment and the generation of high concentrations of nanostructured aerosols if necessary.
Laboratory determination of gravimetric correction factors for real-time area measurements of electronic cigarette aerosols
Published in Aerosol Science and Technology, 2022
Sinan Sousan, Jack Pender, Dillon Streuber, Meaghan Haley, Will Shingleton, Eric Soule
TSI provides the Multi-Instrument Manager (MIM) software (version 3.0) to perform the SMPS and OPS data curve fitting using a lognormal distribution function. The default automated curve fitting options were used for these calculations. The mass median diameter (MMD) and geometric standard deviation (GSD) were tabulated for the MiniWRAS, SMPS, OPS, and the curve fitted data. The aerosol size distribution for MiniWRAS and the SMPS + OPS fitted data were plotted for each ECIG generation method. Particle size was converted to volumetric particle diameter for all monitors. PG and VG, once aerosolized, generate liquid particles, and those aerosol particles are spherical in shape. Therefore, this study assumed the shape factor as 1 for all aerosol generated from different ECIG types (Hinds 1999). The density was assumed as 1.16 g/ml, based on a one-to-one ratio of P.G. (1.04 g/ml) and V.G. (1.27 g/ml) (Sleiman et al. 2016).
Estimated dermal exposure to nebulized pharmaceuticals for a simulated home healthcare worker scenario
Published in Journal of Occupational and Environmental Hygiene, 2020
Simileoluwa Ishau, John F. Reichard, Andrew Maier, Mamadou Niang, Michael Yermakov, Sergey A. Grinshpun
Our results suggest some practical steps for exposure reduction. Exposure reduction based on engineering and nebulizer product design is consistent with the preferred hierarchy of controls. Research on design of nebulizer drug delivery devices to improve delivery efficiency could also reduce the concentration of aerosolized drug particles in the air. From the engineering control perspective, while it might appear beneficial to open the windows or use directional fans to reduce the amount of the medication in the room air, exposure reduction is highly dependent on the direction of the air movement relative to the patient and worker. Additionally, administrative controls are likely to be effective in reducing exposures. Home healthcare agencies and hospitals can provide training to their staff on how to protect themselves from dermal over-exposure when administering medications. The training should include instructions on choosing an appropriate operational distance (where risk of over-exposure is lowest and hands-on care is not impacted) and maintaining adequate positioning techniques based on the direction of the air supply to the room or treatment area. The provision of personal protective equipment (PPE) could also help mitigate dermal deposition. Even a simple pair of gloves, would protect an additional 5% of the exposed body surface area, which based on our study would reduce the deposited dermal dose by about 20%. Together this combination of actions provides a potential exposure reduction program relevant to HHCW scenarios.
Development of a Portable Aerosol Collector and Spectrometer (PACS)
Published in Aerosol Science and Technology, 2018
Changjie Cai, Geb W. Thomas, Tianbao Yang, Jae Hong Park, Sivaram P. Gogineni, Thomas M. Peters
We measured the response time to achieve a stable number concentration after a valve switch (n = 6 stages ×3 replications =18 tests). A knowledge of response time is needed to set an appropriate delay before detector concentrations are used in calculations. We measured the response time for each stage using a mixed aerosol of fresh fume, aged metal fume, and Arizona road dust. Fresh fume was produced with a spark discharge system to represent an ultrafine mode. Aged metal fume produced with a second spark discharge system was passed through two coagulation chambers in series (2 coagulation chamber ×200 L = 400 L) to allow the fume to age into a fine mode. Arizona road dust was aerosolized using a fluidized bed aerosol generator to represent the coarse mode. This mixed aerosol was injected into the mixing/dilution chamber (Figure 3). The valves of the size selector were opened sequentially for 30 s one at a time. For each stage, the response time was measured as the time to reach 95% of the steady-state number concentration by the WCPC after the valve for that stage was opened.