scholarly journals The Giant Nucleus Impactor (GNI)—A System for the Impaction and Automated Optical Sizing of Giant Aerosol Particles with Emphasis on Sea Salt. Part I: Basic Instrument and Algorithms

2020 ◽  
Vol 37 (9) ◽  
pp. 1551-1569
Author(s):  
Jørgen B. Jensen ◽  
Stuart P. Beaton ◽  
Jeffrey L. Stith ◽  
Karl Schwenz ◽  
Marilé Colón-Robles ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
High Volume ◽  
Optical Microscope ◽  
Sample Volume ◽  
Measurement Range ◽  
Polystyrene Latex ◽  
Sea Salt ◽  
Spherical Cap ◽  
Activity Measurements ◽  
Giant Nucleus

AbstractSize distributions of giant aerosol particles (dry radius larger than 0.5 μm, sometimes referred to as coarse-mode aerosol particles) are not well characterized in the atmosphere. Measurements are problematic for these particles because they (i) occur in low concentrations, (ii) have difficulty in passing through air inlets, (iii) may be dry or deliquesced particles, and (iv) if sampled by impaction, typically require labor-intensive methods. In this study, a simple, high-volume impaction system called the Giant Nucleus Impactor (GNI), based on free-stream exposure of polycarbonate slides from aircraft, is described along with an automated optical microscope–based system for analysis of the impacted particles. The impaction slides are analyzed in a humidity-controlled chamber (typically 90% relative humidity) that ensures deliquescence of soluble (typically sea salt) particles. A computer-controlled optical microscope with two digital cameras is used to acquire and analyze images of the aerosol particles. At relative humidities above deliquescence (74% RH for sea salt), such particles will form near-spherical cap solution drops on the polycarbonate slides. The sea-salt mass in each giant aerosol particle is then calculated using simple geometry and published water activity measurements. The system has a sample volume of about 10 L s−1 at aircraft speeds of 105 m s−1. For salt particles, the measurement range is from about 0.7 μm dry radius to at least 16 μm dry radius, with a size-bin resolution of 0.2 μm dry radius. The sizing accuracy was tested using polystyrene latex (PSL) beads of known size.

A New Instrument for Determining the Coarse-Mode Sea Salt Aerosol Size Distribution

2021 ◽  
Author(s):  
Chung Taing ◽  
Katherine L. Ackerman ◽  
Alison D. Nugent ◽  
Jorgen B. Jensen
Keyword(s):  
Size Distribution ◽  
Atmospheric Chemistry ◽  
Optical Microscope ◽  
Sea Salt ◽  
Aerosol Size Distribution ◽  
Sample Collection ◽  
Sea Salt Aerosol ◽  
Coarse Mode ◽  
New Instrument ◽  
Giant Nucleus

AbstractSea salt aerosol(s) (SSA) play a significant role in the atmosphere through aerosol direct and indirect effects, and in atmospheric chemistry as a source of tropospheric bromine. In-situ measurements of coarse-mode SSA particles are limited because of their low concentration and relatively large sizes (dry radius, rd > 0.5 μm). With this in mind, a new, low-cost, easily usable method for sampling coarse-mode SSA particles in the marine boundary layer was developed. A SSA particle sampler that uses an impaction method was designed and built using 3D printing and Arduino microcontrollers and sensors. It exposes polycarbonate slides to ambient airflow remotely on a kite-based platform to capture coarse-mode SSA particles. Because it is a smaller version of the Giant Nucleus Impactor (GNI), designed for use on aircraft, it is named the miniature-Giant Nucleus Impactor, or “mini-GNI”. After sample collection, the same optical microscope methodology utilized by the GNI was used to analyze the wetted salt particles that impacted onto the slides. In this proof-of-concept study, multiple mini-GNIs were attached serially to a kite string, allowing for sampling at multiple altitudes simultaneously. The robustness of the results from this new instrument and methodology for sampling at ambient RH (~ 75 %) the SSA particle size distribution with rd > 3.3 μ m are compared with a similar study. We find that the SSA particle number concentration decreases weakly with altitude and shows no correlation to instantaneous U10 wind speed along the windward coastline of O‘ ahu in the Hawaiian Islands.

scholarly journals Laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF): performance, reference spectra and classification of atmospheric samples

2018 ◽  
Vol 11 (4) ◽  
pp. 2325-2343 ◽  
Author(s):  
Xiaoli Shen ◽  
Ramakrishna Ramisetty ◽  
Claudia Mohr ◽  
Wei Huang ◽  
Thomas Leisner ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Aerosol Particle ◽  
Mass Spectrometer ◽  
Size Range ◽  
Aerosol Particles ◽  
Time Of Flight ◽  
Polystyrene Latex ◽  
Dust Particles ◽  
Data Set ◽  
Flight Mass Spectrometer

Abstract. The laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF, AeroMegt GmbH) is able to identify the chemical composition and mixing state of individual aerosol particles, and thus is a tool for elucidating their impacts on human health, visibility, ecosystem, and climate. The overall detection efficiency (ODE) of the instrument we use was determined to range from  ∼  (0.01 ± 0.01) to  ∼  (4.23 ± 2.36) % for polystyrene latex (PSL) in the size range of 200 to 2000 nm,  ∼  (0.44 ± 0.19) to  ∼  (6.57 ± 2.38) % for ammonium nitrate (NH4NO3), and  ∼  (0.14 ± 0.02) to  ∼  (1.46 ± 0.08) % for sodium chloride (NaCl) particles in the size range of 300 to 1000 nm. Reference mass spectra of 32 different particle types relevant for atmospheric aerosol (e.g. pure compounds NH4NO3, K2SO4, NaCl, oxalic acid, pinic acid, and pinonic acid; internal mixtures of e.g. salts, secondary organic aerosol, and metallic core–organic shell particles; more complex particles such as soot and dust particles) were determined. Our results show that internally mixed aerosol particles can result in spectra with new clusters of ions, rather than simply a combination of the spectra from the single components. An exemplary 1-day ambient data set was analysed by both classical fuzzy clustering and a reference-spectra-based classification method. Resulting identified particle types were generally well correlated. We show how a combination of both methods can greatly improve the interpretation of single-particle data in field measurements.

scholarly journals Polarization properties of aerosol particles over western Japan: classification, seasonal variation, and implications for air quality

2016 ◽  
Author(s):  
X. L. Pan ◽  
I. Uno ◽  
Y. Hara ◽  
K. Osada ◽  
S. Yamamoto ◽  
...  
Keyword(s):  
Air Quality ◽  
Aerosol Particles ◽  
Threshold Value ◽  
Sea Salt ◽  
Spherical Particles ◽  
Aerosol Composition ◽  
Anthropogenic Pollutants ◽  
Online Measurements ◽  
Dependent Polarization ◽  
Western Japan

Abstract. Ground-based observations of the polarization properties of aerosol particles using a polarization optical particle counter (POPC) were performed from October 2013 to January 2015 at a suburban site in the Kyushu area of Japan. By conducting an analysis of online measurements of aerosol composition, we investigated size-dependent polarization characteristics for three typical aerosol types (anthrop ogenic pollutants, dust, and sea salt). We found that, for supermicron particles, its depolarization ratio (DR, the fraction of s-polarized signal in the total back ward light scattering signal) generally increased with the particle size, and a threshold value of 0.1 could be used to identify the irsphericity. In summer, air pollution was less serious, and the DR of aerosol particles was relatively small due to the influence of spherical sea salt particles in high humidity conditions. This study indicated that air masses were transported across the Asian continent and contained not only anthropogenic pollutants, but also large amounts of non-spherical particles (i.e., dust), which could impact on the air quality in western Japan, especially in winter and spring. The variation of number fraction of spherical particles did not correlate with relative humidity averaged along the trajectories of air parcels, indicating the coexistence of hydrophobic substances (e.g., mineral dust and organics), although the sulfate and nitrate mass concentrations were high.

scholarly journals Rubber Dam Isolation and High-Volume Suction Reduce Ultrafine Dental Aerosol Particles: An Experiment in a Simulated Patient

2020 ◽  
Vol 10 (18) ◽  
pp. 6345
Author(s):  
Julián Balanta-Melo ◽  
Albio Gutiérrez ◽  
Gustavo Sinisterra ◽  
María del Mar Díaz-Posso ◽  
David Gallego ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Aerosol Particles ◽  
High Volume ◽  
Simulated Patient ◽  
Volume Distribution ◽  
Risk Of Infection ◽  
Dental Services ◽  
Total Particulate Matter ◽  
Rubber Dam ◽  
Average Size

The ongoing Coronavirus Disease 2019 (COVID-19) pandemic has triggered the paralysis of dental services ascribed to the potential spread of severe acute respiratory syndrome (SARS)-CoV-2. Aerosol-generating procedures (AGPs) are common in dentistry, which in turn increase the risk of infection of the dental personnel due to the salivary presence of SARS-CoV-2 in COVID-19 patients. The use of rubber dam isolation (RDI) and high-volume evacuators (HVE) during AGPs is recommended to control dental aerosols, but the evidence about their effectiveness is scarce. This first study aimed to compare, in a simulated patient, the effectiveness of the following strategies: standard suction (SS), RDI and RDI + HVE. Using the laser diffraction technique, the effect of each condition on the volume distribution, average size and concentration of coarse (PM10), fine (PM2.5) and ultrafine (PM0.1) particles were evaluated. During the teeth drilling, the highest volume fraction of dental aerosol particles with SS was below 1 μm of aerodynamic diameter. Additionally, the RDI + HVE significantly reduced both the ultrafine dental aerosol particles and the concentration of total particulate matter. AGPs represent a potential risk for airborne infections in dentistry. Taken together, these preliminary results suggest that isolation and high-volume suction are effective to reduce ultrafine dental aerosol particles.

scholarly journals Mixing states of Amazon-basin aerosol particles transported over long distances using transmission electron microscopy

2020 ◽  
Author(s):  
Kouji Adachi ◽  
Naga Oshima ◽  
Zhaoheng Gong ◽  
Suzane de Sá ◽  
Adam P. Bateman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amazon Basin ◽  
Mineral Dust ◽  
Aerosol Particles ◽  
Sea Salt ◽  
Anthropogenic Sources ◽  
Natural Sources ◽  
Transmission Electron ◽  
Mixing States

Abstract. The Amazon basin is important for understanding the global climate both because of its carbon cycle and as a laboratory for obtaining basic knowledge of the continental background atmosphere. Aerosol particles play an important role in the climate and weather, and knowledge of their compositions and mixing states is necessary to understand their influence on the climate. For this study, we collected aerosol particles from the Amazon basin during the Green Ocean Amazon (GoAmazon2014/5) campaign (February to March 2014) at the T3 site, which locates about 70 km from Manaus, and analyzed using transmission electron microscopy (TEM). TEM has better spatial resolution than other instruments, which enables us to analyse the occurrences of components that attach to or are embedded within other particles. Based on the TEM results of more than 10,000 particles from several transport events, this study shows the occurrences of individual particles including compositions, size distributions, number fractions, and possible sources of materials that mix with other particles. Aerosol particles during the wet season were from both natural sources such as the Amazon forest, Saharan desert, Atlantic Ocean, and African biomass burning and anthropogenic sources such as Manaus and local emissions. These particles mix together at an individual particle scale. The number fractions of mineral dust and sea-salt particles increased almost three-fold when long-range transport (LRT) from the African continent occurred. Nearly 20 % of mineral dust and primary biological aerosol particles attached sea salts on their surfaces. Sulfates were also internally mixed with sea-salt and mineral dust particles. The TEM element mapping images showed that several components with sizes of hundreds of nanometres from different sources commonly occur within individual LRT aerosol particles. We conclude that many aerosol particles from natural sources change their compositions by mixing during transport. The compositions and mixing states of these particles after emission result in changes in their hygroscopic and optical properties and should be considered when assessing their effects on climate.

Sizing and Positioning Algorithm for 1 µm to 10 µm Particles Using Shadowgraphy

2013 ◽  
Author(s):  
Michael J. Robinson ◽  
Zakaria Mahmud ◽  
Orven F. Swenson ◽  
Justin Hoey
Keyword(s):  
Relative Position ◽  
Scientific Community ◽  
Aerosol Particles ◽  
Measurement Range ◽  
Object Plane ◽  
The Past ◽  
Current State ◽  
Imaging Camera ◽  
Positioning Algorithm ◽  
State Of Art

Measuring flows of aerosol particles of less than 10 μm diameter has proven a challenge in the past. Previously, our work included a brief review of the current state-of-art for aerosol measurements where accurate sizing was limited to particles greater than 5 μm. We developed a sizing and positioning algorithm (SPA) to accurately calculate both the diameter of a spherical particle, and the relative position of that particle to the object plane of the imaging camera for particles down to 3 μm in diameter. Our current work further extends the measurement range down to 1 μm particles. This algorithm has great benefit for the scientific community interested in small-particle aerosol flows.

Lipase activity measured in serum by a continuous-monitoring pH-Stat technique--an update.

1989 ◽  
Vol 35 (8) ◽  
pp. 1688-1693 ◽  
Author(s):  
N W Tietz ◽  
J R Astles ◽  
D F Shuey
Keyword(s):  
Olive Oil ◽  
Continuous Monitoring ◽  
Hydroxypropyl Methylcellulose ◽  
Reference Interval ◽  
Sample Volume ◽  
Standard Curve ◽  
Activity Measurements ◽  
Ph Stat ◽  
Stat Method ◽  
Assay Conditions

Abstract Using recent knowledge regarding the roles of colipase, bile acids, Ca2+, and emulsifiers, we optimized a previously published pH-Stat method for lipase (EC 3.1.1.3) activity measurements. The recommended assay conditions are: olive oil/triolein, 100 mL/L; sodium glycocholate, 35 mmol/L; Ca2+, 8.5 mmol/L; and colipase, 6.0 mg/L. The sample volume is 0.10 mL, the reaction pH 9.0, the temperature 30 degrees C, and the concentration of titrant 15 mmol/L. Hydroxypropyl methylcellulose, 20 g/L, replaces acacia as emulsifier to avoid inhibition by excess Ca2+. The standard curve is linear to greater than 4566 U/L. The reference interval with olive oil as substrate is 30-235 U/L. Lipase activities with triolein substrate are 9.9% greater than with olive oil. Interference by pancreatic carboxylesterase (EC 3.1.1.1) activity is inhibited by incubating the sample with diisopropylfluorophosphate. Results correlate well with those by the optimized SingleVial method of Boehringer Mannheim Diagnostics (r = 0.997) and the immunochemical assay of Beckman Instruments, Inc. (r = 0.995). Correlation with the aca method (E.I. DuPont de Nemours & Company) is less satisfactory (r = 0.892), probably owing to lack of colipase in the latter method.

A Precise Position Measurement System of Roll-to-Roll Printing Using Burst Alignment Patterns

2018 ◽  
Author(s):  
Taehyeong Kim ◽  
Dongho Oh ◽  
Youngjin Kim ◽  
Jihyeon Kim ◽  
Byeongcheol Lee
Keyword(s):  
Measurement System ◽  
High Speed ◽  
Printed Electronics ◽  
High Volume ◽  
Measurement Range ◽  
Generation Process ◽  
Position Measurement ◽  
Process Technology ◽  
Precise Position ◽  
Roll To Roll

Printed electronics is a next-generation process technology that is suitable for high speed and high volume production and can make electronic devices and circuits on flexible materials. To commercialize printed electronics, it is necessary to improve the alignment precision of printing. In order to improve the alignment precision of the roll-to-roll process, accurate measurement of the web position is required. Therefore, in the previous research of this paper, we proposed a measurement system of the moving direction and the lateral movement using an encoder. However, in the previous study, the direction of error control had to be set according to the measurement position of the encoder, and the measurement range was so narrow. In this paper, we propose a measurement system that can detect the direction of error and increase the effective measurement range using the burst alignment pattern that generates the burst signal. Applying it to roll-to-roll printing position measurement systems, measurements can be performed with greatly improved efficiency and measurement range.

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