Particle and vapor measurements typically include sampling tubing causing sampling losses therein. Correcting measured concentrations from the sampling losses using the calculated penetration efficiencies of straight tubes is a satisfactory approximation if sub-micrometer particles are of interest. However, in addition to inertial impaction of larger particles, bends in the tubing can cause a significant

Transmissivity and absorptivity measurements were carried out simultaneously in the visible (wavelength of 532 nm) at laboratory conditions using particle-laden filters obtained from a three-wavelength particle/soot absorption photometer (PSAP). The particles were collected on filters from wildland fires over the Pacific Northwest during the Department of Energy Biomass Burning Observation Project

Molecular clusters are ubiquitous constituents of the ambient atmosphere, that can grow into larger sizes forming new aerosol particles. The formation and growth of small clusters into aerosol particles remain one of the largest uncertainties in global climate predictions. This has made the modelling of atmospheric molecular clustering into an active field of research, yielding direct molecular level

This technical note documents the fabrication and performance of multiplexed electrospray emitters by rapid laser micromachining. A low cost 1064-nm fiber laser marker system is used to precisely, rapidly and selectively remove materials from a sheet of conductive silicone rubber, which is chemically inert. The laser pulse energy, scanning speed and machining path are judicially chosen to create clean

Many governments have instructed the population to wear simple mouth-and-nose covers or surgical face masks to protect themselves from droplet infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in public. However, the basic protection mechanisms and benefits of these masks remain controversial. Therefore, the aim of this work is to show from a fluid physics point of view

This study aims to evaluate the filtration performance of three commercially available (3M 8210 respirator, Halyard 48207 surgical mask, and 3M 1820 procedure mask) and two alternative face mask and respirator materials (Halyard H600 sterilization wrap and Cummins EX101) after selected decontamination treatments, including isopropanol (IPA) treatments (soaking or spraying), ultraviolet germicidal irradiation

The discrete-sectional method to solve the general dynamic equations is a useful tool for the simulation of an evolving aerosol population. This tutorial is intended to equip the reader with the necessary knowledge to implement this method for a single component system. To this end, we provide step-by-step instructions on the construction of a discrete-sectional model, including details on simulation

Bipolar charging and neutralization of aerosol particles below 100 nm in a laminar flow tube with a uniform generation rate of mass- and mobility-distributed heterogeneous ions has been studied theoretically, and compared to the case of homogeneous, monodisperse ions. Two types of homogeneous ions have been examined: type-I, having the arithmetic mean mass and mobility of the heterogeneous ions; and

3D printers have been widely used as a tool for prototype manufacturing in industries, schools, and homes. During operation, 3D printers emit ultrafine particles that could be inhaled by the user and induce adverse health effects. Thus, exposure to ultrafine 3D-printing generated particles has drawn the attention of occupational and environmental health researchers. In this study, a recently developed

New Particle Formation (NPF) is regularly observed to occur in heavily polluted Chinese megacities. However, in these NPF events, the survival probability of small clusters into larger aerosol particles is higher than theoretically predicted. One explanation for this could be that the loss rate of clusters due to scavenging by pre-existing particles, which is described by condensation sink, is lower

Black carbon, as a series of light-absorbing carbonaceous material, contributes significantly to current global warming. Black carbon has always been considered a product of incomplete combustion of fossil fuels and vegetation. In the road transport sector, combustion exhaust is thought to be the primary source of black carbon. This study uses a pin-on-disc tribometer to simulate automotive disc brake

Particle size distributions (PSDs) of engine blow-by aerosol are commonly obtained with an optical particle counter (OPC), but representative measurements are challenging due to high number concentrations, elevated temperatures, presence of saturated vapor, as well as unsteady flow conditions. A comprehensive study of blow-by aerosol sampling/conditioning and OPC performance in such an environment

Several decades of developing laser induced incandescence (LII) as a combustion diagnostic have led to great advances in understanding soot formation. The bulk of diagnostic development has focused on time-resolved LII (TiRe-LII) where heating of soot particles using a laser, and the subsequent particle cooling, can be measured and matched to a model to determine soot primary particle size. These models

Interest in understanding gas-to-particle phase transformation in several disciplines such as atmospheric sciences, material synthesis, and combustion has led to the development of several distinct instruments that can measure the particle size distributions down to the sizes of large molecules and molecular clusters, at which the initial particle formation and growth takes place. These instruments

Aerosols were produced from a MOX (Mixed Oxide of uranium and plutonium) sample by laser heating up to 4000 K under atmospheric conditions. They were collected with a cascade impactor as function of their aerodynamic size, and studied by SEM, EDS, TEM, EELS, SAED and ICPMS. The uranium and plutonium concentrations were related to the aerosol morphology, size and formation temperature. A clear decrease

Ultrafine particle behavior in electro-hydrodynamic (EHD) flow induced by corona discharge is studied experimentally and numerically. The EHD flow serves as a primary particle aspiration/sampling mechanism, the collector does not require any additional flow generation. Multiphysics numerical model couples the ion transport equation and the Navier-Stokes equations (NSE) to solve for the spatiotemporal

Electrical mobility and mass of atmospheric ions are of great importance, since both properties jointly determine their charging states. In this work, different carrier gases of bottle N2, bottle air, and particle-free lab air were passed through a TSI® soft X-ray aerosol neutralizer to produce both positive and negative ions. The electrical mobilities and mass-to-charge ratios of these ions were measured

Quantification of airway deposition of aerosol particles is essential for the assessment of health risks of detrimental particles. Knowledge of deposition distribution is important also in the case of treatment with aerosolised drugs. It is also worth considering that deposition of inhaled particles in severe asthmatics can be different from the deposition in healthy subjects due to the modified breathing

It has been confirmed that the coronavirus disease 2019 (COVID-19) can transmit through droplets created when an infected human coughs or sneezes. Accordingly, 1.83-m (6-feet) social distancing is advised to reduce the spread of the disease among humans. This is based on the assumption that no air circulation exists around people. However, it is not well investigated whether the ambient wind and relative

An analysis is presented of the evolution of a narrow ion beam, produced for instance by an electrospray source, in ambient pressure air. To minimize beam broadening, an intense axial electric field E is externally imposed. Still, radial beam broadening due to the ionic diffusivity D and space charge must be accounted for. Ignoring axial contributions of diffusion and space charge, a simple second

Electrical Mobility is a transport property that describes a particle behavior in the gas phase. When dealing with the free molecular regime, ascertaining the shape of a nanoparticle or an ion directly from measurements of mobility becomes quite difficult as the particle no longer can be assumed to have spherical shape. Here we propose an efficient parallelized tool, IMoS, that makes use of all-atom

Moving towards two-dimensional distributions of particle properties is important to the study of aerosol formation, aerosol climate impacts, and aerosols in material science. This paper builds on existing work to examine Bayesian or statistical approaches to inverting tandem particle mass analyzer (PMA) and differential mobility analyzer (DMA) data to retrieve the two-dimensional mass-mobility distribution

This study numerically investigates the effect of hygroscopicity on transport and deposition of particles in severe asthmatic lungs with distinct airway structures. The study human subjects were selected from two imaging-based severe asthmatic clusters with one characterized by non-constricted airways and the other by constricted airways in the lower left lobe (LLL). We compared the deposition fractions

A low cost, easy-to-manufacture particle classification device for coarse mode, supermicrometer particles and droplets remains important for a variety of industries and environmental measurements, including agricultural sprays, pharmaceutical powders, spray drying processes, precipitation, and dust storms. While optical techniques can typically be used to analyze particle sizes in this range (20 μm–100 μm)

Oxide nanoparticle growth from vapor phase precursors occurs in high temperature aerosol reactors first via the formation of nanoclusters, which are nanometer-scale condensed-phase species composed of 101-102 atoms. The binding rate for nanoclusters, defined as the rate at which two nanoclusters collide with and stick to one another, is hence of interest in predicting nanoparticle size distribution

The resistive particulate matter sensor is a simple device that transduces the presence of soot through impedance change across inter-digital electrodes (IDEs). We investigate the information provided by impedance spectroscopy over the frequency range from 100 Hz to 10 kHz for two purposes. The first is to investigate the opportunities for an improved sensor response to particulate matter (PM), based

The International Civil Aviation Organization has established new regulatory standards for emissions certification of non-volatile particulate matter (nvPM) from aircraft turbine engines. The adoption of the nvPM emissions regulatory standards required development of a standardized sampling and measurement methodology, and rigorous testing. Three reference systems for aircraft engine nvPM emissions

This study was conducted to investigate PM emissions and performance of SI engines fueled with butanol-methanol-gasoline during air dilution operation. Iso-butanol and methanol were blended with gasoline at volume concentrations of up to 40% (10, 20 vol% iso-butanol and methanol, respectively). The effects of lean mixture on engine performance and PM emissions with blends were investigated to find

A numerical analysis is presented of the neutralization of a dilute electrospray by a corona discharge of polarity opposite to that of the spray droplets in the gap between two parallel disks charged to different electric potentials. An Eulerian description of the spray is combined with a transport equation for the corona ions and mass and momentum conservation equations for the gas. Two configurations

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The article noted above presents and discusses results which have been already presented in a previously published article by the same authors: https://doi.org/10.3390/ecas2017-04131 and additionally contains identical passages to the same previously published article

The Differential Mobility Analyzer (DMA) is currently the most effective instrument for sizing sub-micrometer aerosol particles. An important requirement to ensure good performance in terms of sizing accuracy and resolution is that the flow field remains laminar and undisturbed along its classification zone. To achieve that, a flow straightener (or flow laminarizer) is employed at the sheath flow inlet

Analysis of the stable carbon isotope 13C in organic carbon (OC) can give insight into sources and atmospheric processing of carbonaceous aerosols, provided the 13C source signatures are known. However, only few data on 13C signatures of OC emitted by common sources of carbonaceous aerosol are available in Europe. We present and evaluate an improved version of a measurement method (1) to obtain δ13C

The activity size distributions of cosmogenic 7Be and the longer living radon progenies 210Pb and 210Po in urban aerosols were measured for summers and winters from, 2014 to the end of 2017.The average seasonal activity median aerosol diameters (AMADs) and mass median aerosol diameters (MMADs) calculated for summer ranged from 0.329 μm to 0.733 μm and were ordered AMADBe-7,

In silico methods can be used to estimate regional deposition of inhaled aerosols in regions of the lung that are inaccessible by direct measurements. Knowledge of deposited dose is important for assessing the efficacy of inhaled pharmaceutical aerosols or the impact from exposure to environmental pollutants. Although patient-specific geometries of the upper airways are widely used nowadays, insufficient

The application of standard online instrumentation, such as scanning mobility particle sizer (SMPS), centrifugal particle mass analyzer or aerosol particle mass analyzer (CPMA/APM), and electrical low-pressure impactor (ELPI+) to low-pressure processes is only possible with extensive modification of the devices and extensive calibrations. A low-pressure ejector is a suitable device to transfer aerosol

The role of the interaction of gas molecules with a surface on the diffusiophoretic force and velocity of a spherical aerosol particle is studied under the conditions of a free molecular regime. Expressions of these physical quantities are obtained for the arbitrary scattering kernels of different species of molecules. Calculations of the force and velocity of diffusiophoresis are carried out with

Spark discharge generators enable a fast, reliable, continuous, and highly reproducible production of nanoparticle aerosols along with a widely tunable size distribution. Graphite spark discharge generators have been particularly applied for studies of instrument calibration, filter testing, soot reactivity studies, and in toxicological risk evaluation of soot. Until now, it has been consensus that

A review of methodologies to measure the bipolar charge distribution of nanoparticles is completed, including their advantages/disadvantages and sequential development. This summary also provides context for a new development, which uses an Aerodynamic Aerosol Classifier (AAC) and Differential Mobility Analyzer (DMA) in tandem for a similar purpose. It is demonstrated that the tandem AAC-DMA system

The paper proposes a methodology to fill a gap in the context of mechanistic particle resuspension models related to the adhesion and lift force lever arms (a): to date, only one experimental observation exists from a centrifuge experiment with a specific particle/surface pair which found rP/a = 100 and assumed that the contact points were symmetric with respect to the particle center (Reeks, M.W.

Recent studies have shown that small expired droplets that contain pathogens may play a significant role in the transmission of respiratory diseases. However, there is little data on the generation of droplets from the bronchioles and their deposition in the lower airways during exhalation. We apply a computational fluid dynamics method to study expiratory air flow in a truncated model of the adult

The behavior of salt particles on a surface filter exposed to a high humidity gas flow and water droplets was studied to gain a better understanding of the influence of water content in its different states on the operational performance of such filters. Two sets of experiments were carried out: in both, polydisperse sodium chloride particles were filtered from a dry air stream onto hydrophobic filter

Aerosol filtration in fibrous filters is one of the principal methods of accurate removal of particulate matter from gas stream. The classical theory of depth filtration in fibrous structures is based on the assumption of existence of single fiber efficiency, which may be used for calculation of overall efficiency of the filter. There are several reasons for inappropriate estimation of the single fiber

Monopolar electrosurgical pencils are used extensively in surgical operations. With such pencils, electric current passes to the tissue, and as such, electrosurgical pencil operation generates a significant amount of thermal energy, which in turn leads to the generation of electrosurgical smoke (ES). The health risks of ES are dependent on the size distributions as well as the morphologies of the produced

Solid or liquid particles within a carrier gas may be deposited on solid surfaces exposed to the gas stream and, in some practical applications, these aerosol deposits have deleterious effects. In order to mitigate these effects, particle repulsive fields may be applied near the surface to reduce the deposition rate. A current blowing through the exposed surface may play this repulsion role with such

Electrostatic charging and deposition of a liquid nano-aerosol was studied in dry air and in technical (3.6 % O2) nitrogen. The experiments have shown that electronic charging of aerosols can be important in technical scale electrostatic precipitators (ESPs). Already at operation voltages just slightly above the corona onset voltage, the contribution of the free electrons to the overall current is

Drift tubes (DT) are prominent tools to classify small ions in the gas phase. This is in contrast with its limited use in the aerosol field at atmospheric pressures where the differential mobility analyzer (DMA) has been the tool of choice. While the DMA has been successful, it does not normally achieve the resolution of a common DT. On the other hand, the size range of the DT is limited as well as

In this study, the unsteady airflow field in a realistic model of human upper airways during the breathing cycle and the fibrous particle transport and deposition were investigated using the CFD method. An anatomically realistic model of airway passage including vestibule to the end of the trachea was constructed from the CT images of a 24-year-old healthy woman. Several user-defined functions (UDFs)

Based on the prior work of Chahl and Gopalakrishnan (2019) to infer particle-ion collision time distributions using a Langevin Dynamics (LD) approach, we develop a model for the non-dimensional particle-ion diffusion charging collision kernel βi or H that is applicable for 0≤ΨE≤60,0≤ΨIΨE≤1,KnD≤2000 (defined in the main text). The developed model for βi for attractive Coulomb and image potential interactions

The generation of a secondary aerosol after impact, consisting of smaller droplets at a given velocity and mass flow, is relevant for various applications. Thus far, the investigations and modelling approaches on spray impact are based on extrapolation of the single-droplet impingement or empirical correlations. The validity of the models presented is limited to the given experimental setup and conditions

Bipolar charging and neutralization of aerosol particles with diameter below 10 nm in a circular tube with uniform ion-pair generation have been studied theoretically to determine the conditions required to reach the stationary charge distribution. In order to reach the stationary distribution the initial ion-to-aerosol number concentration ratio, Nin/nin, and the Ninτ product (τ is the mean aerosol

We studied the effect of gravitational sedimentation on the dispersion of 0.5 and 1 micrometer-diameter particle boluses within a two-dimensional symmetric six-generation model of the human acinus. Boluses were introduced at the beginning of a 2-s inspiration immediately followed by a 4-s expiration, in normal gravity (1 G) and in the absence of gravity (0 G). The flow corresponded to a flow rate at