Monte Carlo simulations and integral equation techniques allow for the flexible and efficient computation of drag and diffusion coefficients for virus mimetic particles. We highlight a Monte Carlo method that is useful for computing the drag on biomimetic particles in the free-molecular regime and a numerical technique to compute a (boundary integral solution) of the Stokes equation in the hydrodynamic

During the spray process, many factors control the disintegration of the liquid sheet at the exit of a nozzle operating in an ambient atmosphere. Understanding the role of these parameters has significant implications on the spray quality. In particular, in agricultural applications, the formation of finer spray droplets during breakup increases the risk of potential off-target movement of the spray

Simulating an evolving aerosol population in a reactor containment is essential for estimating the radioactivity that is possible to leak to the environment. In this study, a sectional model is developed to simulate multi-component aerosol dynamics in the containment during severe accidents of a pressurized water reactor by improving the widely used MAEROS (Multicomponent AEROSol) model. An important

Indoor respirable suspended particles may accumulate on textured surfaces such as sofa surfaces and office partitions via particle deposition. Previous studies mainly focus on particle deposition on non-patterned rough surfaces or patterned surfaces with texture scale larger than millimeters, and it is generally concluded that deposition rate increases due to the roughness. However, many indoor surfaces

In collaboration with 16 musicians from the Minnesota Orchestra, we assess the airflow and particle concentration emitted from ten wind instruments under realistic performance conditions. Anemometer and schlieren measurement techniques are used to quantify the air flow, and aerodynamic particle sizer, laser sheet, and digital inline holography techniques are used to measure the particle concentration

In China particulate matter (PM) is the leading environmental risk factor to morbidity and mortality, with transport being the main source of PM pollution in cities. China VI emission limit standards, which are one of the most stringent worldwide, have only recently been introduced and there is lack of studies assessing the PM emissions of new engines. In Europe, there are discussions ongoing to permit

The detachment of particle structures from a stiff single fiber exposed to an airflow has been investigated by (Jankowska et al., 2000; Larsen, 1958; Löffler, 1972; Przekop et al., 2004; Qian et al., 1997; Zoller et al., 2020). In order to detach particle piles from a stiff single fiber, airflow velocities above 1.2 m/s are required. While these values are well above typical operational parameter for

Aerosol deposition from laminar flow in a horizontal circular tube is studied analytically considering the combined mechanisms of Brownian diffusion and gravitational settling, and the mean concentration and deposition velocity are calculated and analyzed by using the theoretical solution. The results show that when both diffusional and gravitational effects are considered, the deposition velocity

This paper, one of several in a special issue of the Journal of Aerosol Science on “Inhaled Aerosol Dosimetry”, covers selected methods for defining the respiratory tract anatomy required as input to inhaled aerosol deposition models, along with some applications and challenges. “Anatomy” refers to the study of biological structures and to the structures themselves. Quantitative anatomical data obtained

The potential of using atmospheric-pressure spark ablation for production of atomic clusters has been shown in the recent past. In this study we used this method to produce atomic clusters in Argon and investigated their chemical composition with an atmospheric pressure interface time-of-flight mass spectrometer (APi-TOF-MS). Both anionic and cationic silver and gold clusters were generated and characterised

The diesel particulate matter (PM) is typically agglomerates of soot coated with condensed organic compounds. Three-dimensional (3D) measurement of PM particle structures is currently not undertaken as established techniques usually damage the structure of PM particles by dissociating or evaporating the condensed organic compounds absorbed on the soot. In this work, PM particles emitted from a diesel

Compared to petroleum diesel, renewable diesel fuels and exhaust aftertreatment systems can reduce primary exhaust emissions that are hazardous to human health and the environment. Secondary aerosol emissions which form upon atmospheric processing have, however, been less studied. This study aimed to quantify the impacts of replacing petroleum diesel with renewable fuels (hydrotreated vegetable oil

Micrometer-sized graphite particles are widely found in nature and industry. Particularly, the graphite dust is an important problem for the pebble-bed high temperature gas-cooled reactor (HTGR), regarding the coupling with the fission products (FPs). Due to the highly irregular disk-like shape, a great gap still exists for understanding the transport-related behaviors of real graphite particles, including

Studies on the combustion of isolated droplets are crucial for gaining insights into the mechanisms of soot formation and destruction in practical combustion devices involving liquid fuels. The light extinction (LE) method is arguably the most popular technique for quantifying soot in laboratory flames and has been used frequently for investigating droplet flames. Fluctuation in the intensity of the

Particle deposition exists widely in life and industrial production. The particle-particle or particle-wall impact is the fundamental problem to exact description of particle deposition process. In this paper, the processes of SiO2 micro-particles impacting onto a flat SUS316 stainless steel with different incident angles under different incident velocities were experimentally studied under normal

As encouraged by Toxicity Testing in the 21st Century, researchers increasingly apply high-throughput in vitro approaches to identify and characterize nanoparticle hazards, including conventional aqueous cell culture systems to assess respiratory hazards. Translating nanoparticle dose from conventional toxicity testing systems to relevant human exposures remains a major challenge for assessing occupational

A butanol-based fast condensation particle counter (Fast CPC, Model 3650, Kanomax Inc., Japan) was characterized in this study with three different types of monodisperse particles, including positively and negatively charged nickel-chromium (Ni/Cr) particles, positively charged tetraheptyl ammonium bromide (THABr) and tetrabutyl ammonium bromide (TBABr) particles, and positively charged polyethylene

Accurate and realistic predictions of the fate of nasally inhaled drugs help to understand the complex fluid-particle dynamics in the nasal cavity. Key elements of such a comprehensive numerical analysis include: (i) inhaled drug-aerosol transport and deposition with air-particle-mucus interactions; and (ii) mucociliary clearance (MCC) dynamics, including drug transport, dissolution and absorption

This study aims to analyze the deposition characteristics of particles of major tree species in urban areas of Korea by conducting experiments. To simulate black carbon (BC) particles emitted by automobiles among particulate matter floating in the roadside air, soot particles are generated using a diffusion flame burner, whereas tire wear particles are generated by the mechanical friction between tires

We have performed highly accurate numerical simulations to investigate prolonged dispersion of novel coronavirus-laden droplets in classroom air. Approximately 10,900 virus-laden droplets were released into the air by a teacher coughing and tracked for 90 min by numerical simulations. The teacher was standing in front of multiple students in a classroom. To estimate viral transmission to the students

The Langevin Dynamics (LD) method (also known in the literature as Brownian Dynamics) is routinely used to simulate aerosol particle trajectories for transport rate constant calculations as well as to understand aerosol particle transport in internal and external fluid flows. This tutorial intends to explain the methodological details of setting up a LD simulation of a population of aerosol particles

Inhaled aerosols whether beneficial or harmful express their effects depending on the amount initially deposited in the body (i.e. the deposition dose), with clearance mechanisms including dissolution, mucociliary transport and translocation then determining retained dose in the respiratory tract. The many regions of the respiratory tract differ in their shapes, cellular makeups, defenses, and pathologies

The 2020 coronavirus pandemic and the following quarantine measures have led to significant changes in daily life worldwide. Preliminary research indicates that air quality has improved in many urban areas as a result of these measures. This study takes a neighborhood-scale approach to quantifying this change in pollution. Using data from a network of citizen-hosted, low-cost particulate matter (PM)

We present a comprehensive update on the studies of atmospheric aging processes for airborne bioaerosols under various laboratory-controlled conditions. We reviewed changes in physical, chemical, and biological properties of aerosolized biological organisms suspended in air under different simulated environmental parameters or open air factors (OAFs). These changes were scrutinized by measuring viability

How dust grains aggregate into planetesimals is still an open question. It is experimentally observed that binary collisions between micron-sized dust grains result in adhesion for collisions up to ∼1 ms−1. However, aggregates at scales ∼1 mm and above have been shown to exhibit fragmentation or bouncing at relevant collision velocities, resulting in a barrier preventing the formation of larger aggregates

Spark discharge nanoparticle generators (SDGs) employ the method of spark ablation to generate nanoparticles (NPs) in the gas phase. The material plume ablated from two bulk electrodes is quenched and carried away by a controlled gas flow. The electrical circuit needed to maintain sparking and the gas/aerosol handling are usually rather simple to implement, therefore many different SDG designs exist

Desktop fused deposition modeling (FDM®) three-dimensional (3D) printers are becoming increasingly popular in schools, libraries, and among home hobbyists. FDM® 3D printers have been shown to release ultrafine airborne particles in large amounts, indicating the potential for inhalation exposure and consequent health risks among FDM® 3D printer users and other room occupants including children. These

Scanning mobility particle sizer (SMPS) is widely used for particle number size distribution measurements of submicron particles. In this work, two TSI® SMPSs equipped with a soft X-ray neutralizer and a Kr-85 neutralizer, respectively, were operated in parallel to measure particle number size distributions of ambient air. An independent TSI® ultrafine condensation particle counter (CPC) was used as

To speculate on human responses from animal studies, scale-up factors (body weight, lung volume, or lung surface area ratios) are currently used to extrapolate aerosol lung deposition from animal to human. However, those existing scale-up methods between animals and humans neglected two important inter-subject variability factors: (1) the effect of anatomical differences in respiratory systems from

This article presents a novel approach towards tackling the balance between filter efficiency and pressure drop by layering micro and nano fibres using melt and solution electrospinning. Polyamide fibre mats were fabricated by a prototype fibre printing apparatus, based on a combination of melt and solution electrospinning. Fibrous mats with favorable filtration performance characteristics were developed

Understanding the transmission phenomena of SARS-CoV-2 by virus-laden droplets and aerosols is of paramount importance for controlling the current COVID-19 pandemic. Detailed information about the lifetime and kinematics of airborne droplets of different size is relevant in order to evaluate hygiene measures like wearing masks but also social distancing and ventilation concepts for indoor environments

Thin films deposited by conventional electrospray of volatile solutions often give rise to rough morphology consisting of “coffee rings” formed by individual sessile droplets. This is due to the long average inter-droplet distance and low merging probability of deposited droplets within the sprayed circular area. We present a quadrupole configuration to form a squeezing electric field that compresses

In this report, a flame spray pyrolysis setup has been examined with various in situ extraction methods of particle samples along the flame axis. First, two precursor formulations leading to the formation of iron oxide nanoparticles were used in a standardized SpraySyn burner system, and the final particle outcome was characterized by a broad range of established powder characterization techniques

Inhaled viral droplets may immediately be expelled and cause an escalating re-transmission. Differences in the deposition location of inhaled viral droplets may have a direct impact on the probability of virus expelling. This study develops a numerical model to estimate the region-specific deposition fractions for inhalable droplets (1–50 μm) in respiratory airways. The results identified a higher

The SAE International has published Aerospace Information Report (AIR) 6241 which outlined the design and operation of a standardized measurement system for measuring non-volatile particulate matter (nvPM) mass and number emissions from commercial aircraft engines. Prior to this research, evaluation of this system by various investigators revealed differences in nvPM mass emissions measurement on the

Differential Mobility Analyzers (DMA) have been studied for decades to classify a wide range of particle sizes. Its correct behavior is determined by the resolution, influenced by Brownian diffusion losses, distortions in the electric and flow field. The design configuration, especially inlets and outlets, can be a reason of these effects, affecting the DMA reliability. One of these configurations

Poly-dispersed particle resuspension by turbulent airflow was experimentally studied in a wind tunnel called BISE. The set-up was carefully validated to produce reference airflows with three absolute pressures and friction velocities values. Monolayer deposits of poly-dispersed tungsten particles on tungsten surfaces were used for the experiments. The fraction of detached particles by size bin from

Calibration of optical counters, condensation particle counters, electrical impactors, filtration efficiency measurement, heterogeneous condensation (and many other laboratory applications in aerosol science and technology) are widely used with singly charged particles classified by a differential mobility analyzer with particles smaller than 1 μm. Nevertheless the method presents an ambiguity because

Aerosol nanoclusters (AN), defined here as molecular aggregates suspended in a gas with dimensions between 2 and 10 nm, are the link between substances that we think of as molecules, or the “gas phase,” and those that we consider as particles, or the “condensed phase.” The ability to measure and model the physical and chemical properties of size-resolved AN, which at present is rudimentary at best

The Aerodynamic Aerosol Classifier (AAC) and Differential Mobility Analyzer (DMA) are aerosol classifiers commonly used to generate a monodispersed aerosol by selecting particles within a narrow range of relaxation times or electrical mobilities, respectively. However, generating an aerosol of homogeneous particles, which has narrow ranges of particle mass, mobility and relaxation time simultaneously

This pilot study evaluated the ability of a lung deposition sampler (LDS) to estimate body burden by comparing lung-deposited and inhalable nickel and chromium exposures to biomarkers of internal dose. A cohort of stainless steel welders (N = 18) wore side-by-side inhalable and lung deposition samplers for two Monday shifts and urine samples were collected pre- and post-shift. Samplers were analyzed

Accurate predictions of aerosol transport, evolution, and deposition in the human airways are crucial for inhalation dosimetry investigations. Inhaled aerosol transported through the airways undergoes thermodynamic changes due to changes in temperature and humidity. Aerosol evolution processes are particularly important for liquid multispecies aerosols. These aerosols are sensitive to condensation

Low-cost particle sensors are rapidly gaining popularity for indoor air quality monitoring, but their accuracy has been shown to vary among products and among environments in which they operate. Previous research has explored the effect of environmental conditions including temperature and humidity on sensor accuracy and found appreciable effects of these variables in many cases. We extend this work

The use of low-cost air pollution sensors mounted on drones is an exciting new approach to conduct affordable and highly resolved air quality measurements. However, the air flow around a drone consists of complex, unsteady turbulent structures which interact directly with ambient particulate matter and gases. These interactions influence the transport of fine particulate matter (e.g. PM2.5) and, subsequently

Inhalation exposure to environmental and occupational aerosol contaminants is associated with many respiratory health problems. To realistically mimic long-term inhalation exposure for toxicity testing, lung epithelial cells need to maintained and exposed under air-liquid interface (ALI) conditions for a prolonged period of time. In addition, to study cellular responses to aerosol particles, lung epithelial