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

Studies on the flow-induced particle resuspension have great significance for engineering applications of many areas, and several established resuspension models have been developed for the analysis of particle resuspension in an atmospheric environment. However, for flow with a non-negligible particle Knudsen number (the ratio between the mean free path of gas and the particle radius), which is commonly

Particle shape strongly influences the diffusion charging of aerosol particles exposed to bipolar/unipolar ions and accurate modeling is needed to predict the charge distribution of non-spherical particles. A prior particle-ion collision kernel βi model including Coulombic and image potential interactions for spherical particles is generalized for arbitrary shapes following a scaling approach that

In 2017, Assembly Bill 617 was approved in state of California, which mandated the allocation of resources for addressing air pollutant exposure disparities in underserved communities across the state. The bill stipulated the implementation of community scale monitoring and the development of local emissions reductions plans. We aimed to develop a streamlined, robust, and accessible PM2.5 exposure

Correlating data from in vitro dissolution testing of inhaled particulate pharmaceuticals or air pollutants with the dissolution and distribution to the blood circulation of the same aerosols following inhalation in vivo is a major challenge. Better methods could benefit both inhaled drug development and the risk assessment of air pollutants. Five properties known to influence the results produced

The resolidified fuel debris from the damaged Fukushima Daiichi reactors must be cut into small pieces prior to removing it from reactor buildings. Submicron radioactive aerosol particles are likely to be generated and dispersed into the primary containment vessel (PCV) atmosphere during this cutting process. However, traditional sprays cannot effectively scavenge aerosol particles with diameters in

Activities such as the suppression of coal dust would benefit from an improved understanding about how the presence of surfactant alters the charge distribution of spray drops. However, there is no standard method to measure charge and size distributions of nozzle-generated spray drops. To fill this gap, a new spray drop charge measurement system was developed to measure a broad range of sizes and

Particulate matter (PM) sensors are popular for distributed monitoring due to their portability, low-cost and networking capabilities. To provide reliable data, these sensors have to be calibrated periodically in the laboratory. This is often done in chambers with several of them co-located, alongside several research grade instruments. It is important to confirm that the aerosol is well distributed

Dynamic modeling of how particulate matter (PM) transport, deposit, and translocate from human respiratory systems to systemic regions subject to indoor and outdoor exposures are essential for case-specific lung dosimetry predictions and occupational health risk assessments. Because of the invasive nature and imaging resolution limitations of existing in vitro and in vivo methods, Computational Fluid-Particle

Electrical Mobility is arguably the property upon which some of the most successful classification criteria are based for aerosol particles and ions in the gas phase. Once the value of mobility is empirically obtained, it can be related to a geometrical descriptor of the charged entity through a size-mobility relationship. Given the multiscale range of sizes in the aerosol field, approaches that can

Structural properties in nonwoven materials, such as porosity and layer thickness, are typically spatially distributed on a micro- and mesoscale. The mesoscale inhomogeneity is visually perceived, inter alia, as the cloudiness of the nonwoven fabric or as inclusions in the bulk material. Differential box counting, which is a fractal based image analysis method, was used to assess the inhomogeneity