scholarly journals Nanoparticle Measurement Through Visualisation

2008 ◽  
Vol 16 (2) ◽  
pp. 22-25
Author(s):  
Bob Carr ◽  
Andrew Malloy
Keyword(s):  
Particle Size ◽  
Particle Number ◽  
Number Concentration ◽  
Sample Type ◽  
Particle Number Concentration ◽  
Particle Interactions ◽  
Nanoparticle Tracking Analysis ◽  
Nanoscale Particles ◽  
Video Images ◽  
Solvent Type

In this article, we will describe how nanoscale particles may be individually visualised (but not imaged) in liquids and from which higher resolution particle size distribution profiles can be obtained compared to other light scattering techniques. The method is called Nanoparticle Tracking Analysis (NTA)Sample preparation is minimal, requiring only dilution with a suitable solvent to an acceptable concentration range (between 10 and 1010 particles per ml depending on sample type). Accurate and reproducible analyses can be obtained from video images of only a few seconds duration and the results allow particle number concentration to be recovered. Given the close to real-time nature of the technique, particle-particle interactions are accessible as is information about sample aggregation and dissemination. All particle types can be measured and in any solvent type providing that the particles scatter sufficient light to be visible (i.e. are not indexed matched).

scholarly journals A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

2013 ◽  
Vol 6 (6) ◽  
pp. 10551-10570
Author(s):  
A. Schladitz ◽  
M. Merkel ◽  
S. Bastian ◽  
W. Birmili ◽  
K. Weinhold ◽  
...  
Keyword(s):  
Particle Size ◽  
Air Quality ◽  
Particle Number ◽  
Zero Point ◽  
Number Concentration ◽  
Quality Monitoring ◽  
Particle Number Concentration ◽  
Air Quality Monitoring ◽  
Total Particle Number ◽  
Total Particle

Abstract. An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The aim of the new feature is to conduct unattended quality control experiments under field conditions at remote air quality monitoring or research stations. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter removing the diffusive particles approximately smaller than 25 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. The other feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. An exemplary one-year data set is presented for the measurement site Annaberg-Buchholz as part of the Saxon air quality monitoring network. The total particle number concentration derived from the mobility particle size spectrometer overestimates the particle number concentration by only 2% (grand average offset). Furthermore, tolerance criteria are presented to judge the performance of the mobility particle size spectrometer with respect to the particle number concentration. An upgrade of a mobility particle size spectrometer with an automated function control enhances the quality of long-term particle number size distribution measurements. Quality assured measurements are a precondition for intercomparison studies of different sites. Comparable measurements will improve cohort health and also climate-relevant research studies.

scholarly journals Evolution of Aerosol Particles in the Rainfall Process via Method of Moments

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Fangyang Yuan ◽  
Fujun Gan
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Method Of Moments ◽  
Particle Number ◽  
Aerosol Particles ◽  
Geometric Mean ◽  
Number Concentration ◽  
Brownian Diffusion ◽  
Particle Number Concentration

The method of moments is employed to predict the evolution of aerosol particles in the rainfall process. To describe the dynamic properties of particle size distribution, the population balance equation is converted to moment equations by the method of moments and the converted equations are solved numerically. The variations of particle number concentration, geometric mean diameter, and geometric standard deviation are given in the cases that the Brownian diffusion and inertial impaction of particles dominate, respectively. The effects of raindrop size distribution on particle size distribution are analyzed in nine cases. The results show that the particle number concentration decreases as time goes by, and particles dominated by Brownian diffusion are removed more significantly. The particle number concentration decreases much more rapidly when particle geometric mean diameter is smaller, and the particle size distribution tends to be monodisperse. For the same water content, the raindrops with small geometric mean diameters can remove particles with much higher efficiency than those with large geometric mean diameters. Particles in the “Greenfield gap” are relatively difficult to scavenge, and a new method is needed to remove it from the air.

scholarly journals Comparison of Three Particle Number Concentration Calibration Standards Through Calibration of a Single CPC in a Wide Particle Size Range

2012 ◽  
Vol 46 (11) ◽  
pp. 1163-1173 ◽  
Author(s):  
Jaakko Yli-Ojanperä ◽  
Hiromu Sakurai ◽  
Kenjiro Iida ◽  
Jyrki M. Mäkelä ◽  
Kensei Ehara ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Number ◽  
Size Range ◽  
Number Concentration ◽  
Particle Number Concentration ◽  
Particle Size Range ◽  
Calibration Standards

scholarly journals Real-World Vehicle Emission Rate of Particle Size Distributions Based on Measurement of Tunnel Flow Coefficient

2021 ◽  
Vol 11 (2) ◽  
pp. 794
Author(s):  
Chaehyeong Park ◽  
Myoungki Song ◽  
Gyutae Park ◽  
Kyunghoon Kim ◽  
Taehyoung Lee ◽  
...  
Keyword(s):  
Particle Size ◽  
Real World ◽  
Particle Number ◽  
Emission Rate ◽  
Traffic Volume ◽  
Number Concentration ◽  
Flow Coefficient ◽  
Vehicle Emission ◽  
Physical Parameters ◽  
Particle Number Concentration

This study aims to analyze the seasonal number concentrations corresponding to each particle size derived from the measurements of exhausts from approximately seven million vehicles on real-world using a pair of the scanning mobility particle sizer to determine the vehicle emission rate. The actual tunnel flow coefficient was investigated for car emission rate based on the measurements of individual physical parameters (i.e., cross section area and length of the tunnel, tunnel wind speed and traffic volume). The mode of particle diameter according to temperatures in respective seasons exhibited a high correlation together with rapid changes at temperature above the breakthrough point. The temperature acted as major cause of determination of final condensation diameter, which is also dependent on diverse environmental effects comprising particle number concentration. The traffic volume of ordinary cars increased by more than twice as much in the period of Asian New Year, the traffic volume of buses/RVs/trucks decreased by more than 25% during weekdays. As a result, the particle number concentration discharged from a unit vehicle was 6.96 × 1012 N/veh·km during weekdays, and the values of weekends appeared as 6.08 × 1012 N/veh·km. The overall averaged particle number concentration based on the actual seasonal road measurements shows 5.82 × 1012 N/veh·km.

scholarly journals Intra-community spatial variability of particulate matter size distributions in southern California/Los Angeles

2008 ◽  
Vol 8 (3) ◽  
pp. 9641-9672 ◽  
Author(s):  
M. Krudysz ◽  
K. Moore ◽  
M. Geller ◽  
C. Sioutas ◽  
J. Froines
Keyword(s):  
Particle Size ◽  
Los Angeles ◽  
Spatial Variability ◽  
Size Distribution ◽  
Particle Number ◽  
Number Concentration ◽  
Particle Number Concentration ◽  
Size Distributions ◽  
Sampling Locations ◽  
Concentration Measurements

Abstract. Ultrafine particle (UFP) number concentrations vary significantly on small spatial and temporal scales due to their short atmospheric lifetimes and multiplicity of sources. To determine UFP exposure gradients within a community, simultaneous particle number concentration measurements at a network of sites are necessary. Concurrent particle size distribution measurements aid in identifying UFP sources, while providing data to investigate local scale effects of both photochemical and physical processes on UFP. From April to December 2007, we monitored particle size distributions at 13 sites within 350 m to 11 km of each other in the vicinity of the Ports of Los Angeles and Long Beach using Scanning Mobility Particle Sizers (SMPS). Typically, three SMPS units were simultaneously deployed and rotated among sites at 1–2 week intervals. Total particle number concentration measurements were conducted continuously at all sites. Seasonal and diurnal size distribution patterns are complex, highly dependent on local meteorology, nearby PM sources, and times of day, and cannot be generalized over the study area nor inferred from one or two sampling locations. Spatial variation in particle number size distributions was assessed by calculating the coefficient of divergence (COD) and correlation coefficients (r) between site pairs. Results show an overall inverse relationship between particle size and CODs, implying that number concentrations of smaller particles (<40 nm) differ from site to site, whereas larger particles tend to have similar concentrations at various sampling locations. In addition, variations in r values as a function of particle size are not necessarily consistent with corresponding COD values, indicating that using results from correlation analysis alone may not accurately assess spatial variability.

scholarly journals Intra-community spatial variability of particulate matter size distributions in Southern California/Los Angeles

2009 ◽  
Vol 9 (3) ◽  
pp. 1061-1075 ◽  
Author(s):  
M. Krudysz ◽  
K. Moore ◽  
M. Geller ◽  
C. Sioutas ◽  
J. Froines
Keyword(s):  
Particle Size ◽  
Los Angeles ◽  
Spatial Variability ◽  
Size Distribution ◽  
Particle Number ◽  
Number Concentration ◽  
Particle Number Concentration ◽  
Size Distributions ◽  
Number Size Distribution ◽  
Sampling Locations

Abstract. Ultrafine particle (UFP) number concentrations vary significantly on small spatial and temporal scales due to their short atmospheric lifetimes and multiplicity of sources. To determine UFP exposure gradients within a community, simultaneous particle number concentration measurements at a network of sites are necessary. Concurrent particle number size distribution measurements aid in identifying UFP sources, while providing data to investigate local scale effects of both photochemical and physical processes on UFP. From April to December 2007, we monitored particle number size distributions at 13 sites within 350 m–11 km of each other in the vicinity of the Ports of Los Angeles and Long Beach using Scanning Mobility Particle Sizers (SMPS). Typically, three SMPS units were simultaneously deployed and rotated among sites at 1–2 week intervals. Total particle number concentration measurements were conducted continuously at all sites. Seasonal and diurnal number size distribution patterns are complex, highly dependent on local meteorology, nearby PM sources, and times of day, and cannot be generalized over the study area nor inferred from one or two sampling locations. Spatial variation in particle number size distributions was assessed by calculating the coefficient of divergence (COD) and correlation coefficients (r) between site pairs. Results show an overall inverse relationship between particle size and CODs, implying that number concentrations of smaller particles (<40 nm) differ from site to site, whereas larger particles tend to have similar concentrations at various sampling locations. In addition, variations in r values as a function of particle size are not necessarily consistent with corresponding COD values, indicating that using results from correlation analysis alone may not accurately assess spatial variability.

scholarly journals A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

2014 ◽  
Vol 7 (4) ◽  
pp. 1065-1073 ◽  
Author(s):  
A. Schladitz ◽  
M. Merkel ◽  
S. Bastian ◽  
W. Birmili ◽  
K. Weinhold ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Number ◽  
Zero Point ◽  
Number Concentration ◽  
Quality Monitoring ◽  
Particle Number Concentration ◽  
Air Quality Monitoring ◽  
Condensation Particle Counter ◽  
Total Particle Number ◽  
Total Particle

Abstract. An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The function control allows unattended quality assurance experiments at remote air quality monitoring or research stations under field conditions. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter while removing diffusive particles smaller than 20 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. Another feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. The performance of the function control is illustrated with the aid of a 1-year data set recorded at Annaberg-Buchholz, a station in the Saxon air quality monitoring network. During the period of concern, the total particle number concentration derived from the mobility particle size spectrometer slightly overestimated the particle number concentration recorded by the condensation particle counter by 2 % (grand average). Based on our first year of experience with the function control, we developed tolerance criteria that allow a performance evaluation of a tested mobility particle size spectrometer with respect to the total particle number concentration. We conclude that the automated function control enhances the quality and reliability of unattended long-term particle number size distribution measurements. This will have beneficial effects for intercomparison studies involving different measurement sites, and help provide a higher data accuracy for cohort health and climate research studies.

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