Brain accumulation of inhaled uranium in the rat depends on aerosol concentration, exposure repetitions, particle size and solubility

Abstract. The presence of bioaerosols in swine production facilities affects the respiratory health of swine workers and pigs. Air ionization (AI) is an affordable technology for removing bioaerosols in the air. The purpose of this study was to assess the effect of AI on aerosols in a ventilated space in terms of reduction in aerosol concentration, changes in particle size distribution, and reduction of airborne Porcine Reproductive and Respiratory Syndrome virus (PRRSV). Experiments were performed in a two-chamber system in which aerosols containing PRRSV were introduced. Tests were conducted for two ventilation rates of 34 and 136 m3 h-1 and two aerosol generation rates of 14.8 and 33.0 mL h-1. The aerosol concentration and size distribution were measured with an aerosol particle size spectrometer. The average reduction in geometric mean diameter of aerosols by AI treatment ranged from 8% to 53%, and reduction in aerosol concentration ranged from 68% to 96%. Ventilation rate was found to affect the efficiency of AI in reducing aerosol concentration; the removal efficiency decreased with increased ventilation rate. The removal efficiency of AI varied with particle size. Specifically, at the low airflow rate, the removal efficiency of AI increased sharply with particle size from 70% at 0.25 µm to 95% at 0.6 µm and reached 100% for particles larger than 6 µm. At the high airflow rate, the removal efficiency varied between 50% to 80% before reaching 100% removal for particles sizes of 7 to 9 µm. The average reduction in PRRSV concentration ranged from 68% to 96%, and the residual PRRSV remaining in the air after treatment ranged from 154 to 4593 viral genome copy number (VGCN) m-3. Ozone generation by the AI system was not measured in this study, and it may be a concern due to the health risk to pigs and workers when using AI systems for removing bioaerosols. Keywords: Air ionization, Air quality, Bioaerosols, Porcine Reproductive and Respiratory Syndrome Virus, Swine.

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Application of Multistep Inversion Method for Online Monitoring Aerosol Particle Size Distribution and Aerosol Concentration

Mathematical Problems in Engineering ◽

10.1155/2020/1983460 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Zhenzong He ◽

Liang Xu ◽

Junkui Mao ◽

Xingsi Han ◽

Biao Zhang

Keyword(s):

Particle Size ◽

Standard Deviation ◽

Particle Size Distribution ◽

Size Distribution ◽

Sampling Time ◽

Aerosol Concentration ◽

Inversion Method ◽

Time Interval ◽

Aerosol Particle Size ◽

Sampling Time Interval

Aerosol concentration in the flow is usually time varying, and aerosol particle size distribution (PSD) is considered to be unchanged, which increases the difficulty of the measurement of aerosol PSD and concentration online. To solve these problems, a kind of multistep inversion method based on the angular light-scattering (ALS) signals is proposed. First, the aerosol PSD is estimated using shuffled frog-leaping algorithms (SFLAs) from relative ALS signals. Then, with aerosol PSD as priori information, the aerosol concentration is obtained by the Kalman filter (KF) algorithm, widely used in the real-time control system of industrial facilities for its ability of fast predictions. The result reveals that the performance of the improved SFLA is better than that of the original SFLA in solving the aerosol PSD. Moreover, in studying the aerosol concentration, more accurate results can be obtained with larger standard deviation of process noise or smaller standard deviation of measurement noise, while decreasing sampling time interval can improve the accuracy of retrieval results and reduce time delay to a certain degree. So, to improve retrieval accuracy, the noise should be controlled, and appropriate sampling time interval should be selected. All the numerical simulations confirm that the methodology provides effective and reliable results in real-time estimating.

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The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph182111523 ◽

2021 ◽

Vol 18 (21) ◽

pp. 11523

Author(s):

Finn F. Duill ◽

Florian Schulz ◽

Aman Jain ◽

Leve Krieger ◽

Berend van Wachem ◽

...

Keyword(s):

Particle Size ◽

Particle Concentration ◽

Substantial Reduction ◽

Aerosol Concentration ◽

Optimal Placement ◽

Cfd Modeling ◽

Risk Of Infection ◽

Duration Of Stay ◽

Increased Risk ◽

The Impact

In the wake of the COVID-19 pandemic, an increased risk of infection by virus-containing aerosols indoors is assumed. Especially in schools, the duration of stay is long and the number of people in the rooms is large, increasing the risk of infection. This problem particularly affects schools without pre-installed ventilation systems that are equipped with filters and/or operate with fresh air. Here, the aerosol concentration is reduced by natural ventilation. In this context, we are investigating the effect of large mobile air purifiers (AP) with HEPA filters on particle concentration and their suitability for classroom use in a primary school in Germany. The three tested APs differ significantly in their air outlet characteristics. Measurements of the number of particles, the particle size distribution, and the CO2 concentration were carried out in the classroom with students (April/May 2021) and with an aerosol generator without students. In this regard, the use of APs leads to a substantial reduction of aerosol particles in the considered particle size range of 0.178–17.78 µm. At the same time, the three APs are found to have differences in their particle decay rate, noise level, and flow velocity. In addition to the measurements, the effect of various influencing parameters on the potential inhaled particle dose was investigated using a calculation model. The parameters considered include the duration of stay, particle concentration in exhaled air, respiratory flow rate, virus lifetime, ventilation interval, ventilation efficiency, AP volumetric flow, as well as room size. Based on the resulting effect diagrams, significant recommendations can be derived for reducing the risk of infection from virus-laden aerosols. Finally, the measurements were compared to computational fluid dynamics (CFD) modeling, as such tools can aid the optimal placement and configuration of APs and can be used to study the effect of the spread of aerosols from a source in the classroom.

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Theoretical and experimental analysis of turbidity fluctuations in the simultaneous measurement of particle size and aerosol concentration

Journal of Aerosol Science ◽

10.1016/s0021-8502(98)00593-x ◽

1998 ◽

Vol 29 ◽

pp. S425-S426

Author(s):

E. Ge´hin ◽

M. Attoui ◽

G. Gre´han

Keyword(s):

Particle Size ◽

Experimental Analysis ◽

Simultaneous Measurement ◽

Aerosol Concentration

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Aerosol concentration and particle size distributions in underground excavations of a hard coal mine

International Journal of Occupational Safety and Ergonomics ◽

10.1080/10803548.2016.1198553 ◽

2016 ◽

Vol 23 (3) ◽

pp. 318-327 ◽

Cited By ~ 3

Author(s):

Krystian Skubacz ◽

Łukasz Wojtecki ◽

Paweł Urban

Keyword(s):

Particle Size ◽

Coal Mine ◽

Aerosol Concentration ◽

Hard Coal ◽

Size Distributions ◽

Particle Size Distributions ◽

Underground Excavations

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Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104972 ◽

1988 ◽

Vol 46 ◽

pp. 582-583

Author(s):

C. J. Chan ◽

K. R. Venkatachari ◽

W. M. Kriven ◽

J. F. Young

Keyword(s):

Particle Size ◽

Raw Materials ◽

Shape Change ◽

Microstructural Characterization ◽

Particle Size Effect ◽

Dicalcium Silicate ◽

Laser Melting ◽

Uniform Size ◽

Cell Shape Change ◽

Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

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Analytical Electron Microscopy study of two vehicle-aged automotive exhaust catalysts having dissimilar activities

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153336 ◽

1989 ◽

Vol 47 ◽

pp. 272-273

Author(s):

Sooho Kim ◽

M. J. D’Aniello

Keyword(s):

Electron Microscopy ◽

Particle Size ◽

Noble Metal ◽

Catalyst Deactivation ◽

Analytical Electron Microscopy ◽

Microscopy Study ◽

Metal Particles ◽

Automotive Exhaust ◽

Exhaust Catalysts ◽

Analytical Electron

Automotive catalysts generally lose-agtivity during vehicle operation due to several well-known deactivation mechanisms. To gain a more fundamental understanding of catalyst deactivation, the microscopic details of fresh and vehicle-aged commercial pelleted automotive exhaust catalysts containing Pt, Pd and Rh were studied by employing Analytical Electron Microscopy (AEM). Two different vehicle-aged samples containing similar poison levels but having different catalytic activities (denoted better and poorer) were selected for this study.The general microstructure of the supports and the noble metal particles of the two catalysts looks similar; the noble metal particles were generally found to be spherical and often faceted. However, the average noble metal particle size on the poorer catalyst (21 nm) was larger than that on the better catalyst (16 nm). These sizes represent a significant increase over that found on the fresh catalyst (8 nm). The activity of these catalysts decreases as the observed particle size increases.

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