Aerodynamic Particle Sizer Spectrometer Research Articles

Polarized light illuminated scattering characteristics of single airborne particle

We demonstrate a method of classifying aerosol particles with different shapes based on the two separated vertical and horizontal polarized beams spaced by 90-100 µm. Model 3321 Aerodynamic Particle Sizer Spectrometer (APS3321) was used to set up an experimental apparatus to test aerosol samples of different shapes, such as spherical oleic acid droplets and elongated crystallized riboflavin. The receiver operating characteristic (ROC) curve was applied to analyze the discrimination ability of the difference in light-scattering intensity to samples with different shapes in the different particle size ranges. The results show that under our experimental conditions, for spherical particles and elongated particles, the distribution trend of the Pf parameter defined by ourselves are different in each particle size range, and the difference between the two particles in the smaller particle size range (about less than 1 µm) seems to be greater than that in the larger one. The relationship between the difference in light-scattering intensity and the elements of the Muller matrix was deduced theoretically. On this basis, the difference in light-scattering intensity of particles with different shapes was calculated by T-matrix. The calculation results show that the method can distinguish spherical and elongated particles well in a certain range of particle sizes (it's approximately 0.3-1.0 µm in diameter). The good agreement between the experimental results and the theoretical calculations indicate the feasibility of the polarized light illuminated scattering characteristics of single airborne particle combined with aerodynamic size information as a new method for aerosol particle shape rapid discrimination.

A method of determining multi-wavelength lidar ratios combining aerodynamic particle sizer spectrometer and sun-photometer

The lidar equation solution for atmosphere requires knowledge of the lidar ratio along the lidar line of sight. The lidar ratio is depended on the wavelength of lidar, so it is difficult to determine the lidar ratios in multi-wavelength lidar. A method that determines the multi-wavelength lidar ratios combining sun-photometer and aerodynamic particle sizer spectrometer (APS) is proposed. The optimal lidar ratios at three wavelengths (355 nm, 532 nm and 1064 nm) are deduced from comparing the aerosol optical depth (AOD) derived from sun-photometer and the multi-wavelength lidar. The feasibility and practicability of this method is tested by the actual experiment. The uncertainty of determining lidar ratios in multi-wavelength lidar is reduced. The aerosol extinction coefficient retrieved using this method is improved with accuracy of 12.8%, 26.3% and 8.2% at 355 nm, 532 nm and 1064 nm respectively.

The Generation Rate of Respirable Dust from Cutting Fiber Cement Siding Using Different Tools.

This article describes the evaluation of the generation rate of respirable dust (GAPS, defined as the mass of respirable dust generated per unit linear length cut) from cutting fiber cement siding using different tools in a laboratory testing system. We used an aerodynamic particle sizer spectrometer (APS) to continuously monitor the real-time size distributions of the dust throughout cutting tests when using a variety of tools, and calculated the generation rate of respirable dust for each testing condition using the size distribution data. The test result verifies that power shears provided an almost dust-free operation with a GAPS of 0.006 g m-1 at the testing condition. For the same power saws, the cuts using saw blades with more teeth generated more respirable dusts. Using the same blade for all four miter saws tested in this study, a positive linear correlation was found between the saws' blade rotating speed and its dust generation rate. In addition, a circular saw running at the highest blade rotating speed of 9068 rpm generated the greatest amount of dust. All the miter saws generated less dust in the 'chopping mode' than in the 'chopping and sliding' mode. For the tested saws, GAPS consistently decreased with the increases of the saw cutting feed rate and the number of board in the stack. All the test results point out that fewer cutting interactions between the saw blade's teeth and the siding board for a unit linear length of cut tend to result in a lower generation rate of respirable dust. These results may help guide optimal operation in practice and future tool development aimed at minimizing dust generation while producing a satisfactory cut.

Investigate the relationship between multiwavelength lidar ratios and aerosol size distributions using aerodynamic particle sizer spectrometer

The real aerosol size distributions were obtained by aerodynamic particle sizer spectrometer (APS) in China YinChuan. The lidar ratios at wavelengths of 355nm, 532nm and 1064nm were calculated using Mie theory. The effective radius of aerosol particles reff and volume C/F ratio (coarse/fine) Vc/f were retrieved from the real aerosol size distributions. The relationship between multiwavelength lidar ratios and particle reff and Vc/f were investigated. The results indicate that the lidar ratio is positive correlated to the particle reff and Vc/f. The lidar ratio is more sensitive to the coarse particles. The short wavelength lidar ratio is more sensitive to the particle Vc/f and the long wavelength lidar ratio is more sensitive to the particle reff. The wavelength dependency indicated that the lidar ratios decrease with increasing the wavelength. The lidar ratios are almost irrelevant to the shape and total particles of aerosol size distributions.

Size distribution characteristics of particulate matter in the top areas of coke oven

To systematically evaluate the environmental exposure information of coke oven workers, we investigated the concentration and size distribution characteristics of the particle matter (PM) in the top working area of coke oven. The aerodynamic particle sizer spectrometer was employed to collect the concentration and size distribution information of PM at a top working area. The PM was divided into PM ≤ 1.0 µm, 1.0 µm < PM ≤ 2.5 µm, 2.5 µm < PM ≤ 5.0 µm, 5.0 µm < PM ≤ 10.0 µm and PM>10.0 µm based on their aerodynamic diameters. The number concentration, surface area concentration, and mass concentration were analyzed between different groups. We also conducted the correlation analysis on these parameters among groups. We found the number and surface area concentration of top area particulate was negatively correlated with particle size, but mass concentration curve showed bimodal type with higher point at PM = 1.0 µm and PM = 5.0 µm. The average number concentration of total particulate matter in the top working area was 661.27 number/cm³, surface area concentration was 523.92 µm²/cm³, and mass concentration was 0.12 mg/m³. The most number of particulate matter is not more than 1 µm (PM(1.0)), and its number concentration and surface area concentration accounted for 96.85% and 67.01% of the total particles respectively. In the correlation analysis, different particle size correlated with the total particulate matter differently. And the characteristic parameters of PM2.5 cannot fully reflect the total information of particles. The main particulate matter pollutants in the top working area of coke oven is PM1.0, and it with PM(5.0) can account for a large proportion in the mass concentration of PM. It suggest that PM1.0 and PM(5.0) should be considered for occupational health surveillance on the particulate matter in the top area of coke oven.

황사 시 제주지역 에어로졸의 수농도 특성

The aerosol number concentration have measured with an aerodynamic particle sizer spectrometer(APS) at Gosan in Jeju Island, which is known as background area in Korea, from March 2010 to February 2011. The obtained results of asian dust events and non-asian dust period have been compared. The results show that the entire averaged aerosol number concentration from APS measurement during asian dust events and non-asian dust period are about 341 particles/ 3 and 240 particles/ 3 , respectively. During asian dust events, the number concentration in small size ranges( 0.4 ) are similar to non-asian dust period, however, those in large size ranges( 0.7 ) are very higher than non-asian dust period. The contributions of the size resolved number concentration(23 channel in 0.25 10.0 ) to total number concentration in that range are dramatically decreased with increased particle size. The contributions of smaller size ranges( 0.4 ) during asian dust events are very low compared with non-asian dust period, on the other hand, those of larger size ranges( 0.4 ) are higher than non-asian dust period. The number concentration in each size range are strongly correlated with the concentration in adjacent size range. And the total aerosol number concentration are depended on the number concentration in range of smaller than 0.58 during non-asian dust period and asian dust events. On the other hand, PM10 mass concentration has mainly affected with the number concentration in range of smaller than 1.0 during non-asian dust period, however, during asian dust events, the mass concentration has mainly affected with the number concentration in range of 0.65 3.0 .

Size distribution and chemical composition of secondary organic aerosol formed from Cl-initiated oxidation of toluene

Secondary organic aerosol (SOA) formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS), respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e., PM2.5), and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed.

대기배경지역 에어로졸의 입경별 수농도 연속 측정

The aerosol number concentration have measured with an aerodynamic particle sizer spectrometer(APS) at Gosan site, which is known as background area in Korea, from January to September 2011. The temporal variation and the size distribution of aerosol number concentration have been investigated. The entire averaged aerosol number concentration in the size range 0.25~32.0 <TEX>${\mu}m$</TEX> is about 252 particles/<TEX>$cm^3$</TEX>. The number concentration in small size ranges(<TEX>${\leq}0.5{\mu}m$</TEX>) are very higher than those in large size ranges, such as, the number concentration in range of larger than 6.5 <TEX>${\mu}m$</TEX> are almost zero particles/<TEX>$cm^3$</TEX>. The contributions of the number concentration to PM10 and/or PM2.5 are about 34%, 20.1% and 20.4% in the size range 0.25~0.28 <TEX>${\mu}m$</TEX>, 0.28~0.30 <TEX>${\mu}m$</TEX> and 0.30~0.35 <TEX>${\mu}m$</TEX>, respectively, however, the contributions are below 1% in range of larger than 0.58 <TEX>${\mu}m$</TEX>. The monthly variations in the number concentration in smaller size range(<1.0 <TEX>${\mu}m$</TEX>) are evidently different from the variations in range of larger than 1.0 <TEX>${\mu}m$</TEX>, but the variations are appeared similar patterns in smaller size range(<1.0 <TEX>${\mu}m$</TEX>), also the variations in range of larger than 1.0 <TEX>${\mu}m$</TEX> are similar too. The diurnal variations in the number concentration for smaller particle(<1.0 <TEX>${\mu}m$</TEX>) are not much, but the variations for larger particle are very evident. Size-fractioned aerosol number concentrations are dramatically decreased with increased particle size. The monthly differences in the size-fractioned number concentrations for smaller size range(<0.7 <TEX>${\mu}m$</TEX>) are not observed, however, the remarkable monthly differences are observed for larger size than 0.7 <TEX>${\mu}m$</TEX>.

Infrared Extinction Properties of Nanostructured and Conventional Particles

Brass flakes and carbon-based particulates are effective obscurants in the infrared (IR) region of the electromagnetic spectrum; however, they are toxic and can cause respiratory problems and environmental concerns. There is a need to develop or identify nontoxic IR obscurants. This research was conducted to determine the potential of nanostructured particles as IR obscurants. Three commercial nanostructured particles were compared with two conventional particles and common obscurants. Experiments involved dispersing a known mass of particles into a particle chamber and measuring the IR transmission through the chamber with a Fourier transform infrared analyzer and the mass concentration with filter samplers. The size distribution of the aerosolized particles was also measured with an aerodynamic particle sizer spectrometer. From the measured data, the mean values of the mass extinction coefficient, σm, and volume extinction coefficient, σv, for the spectral bands of interest (i.e., 3–5 μm and 8–12 μm) were calculated. Results showed that ISO fine test dust, NaHCO3 and NanoActive TiO2 (for 3–5 μm) appeared to be the most promising alternatives to brass or graphite flakes. By manipulating the size and/or morphology of these particles, it might be possible to enhance their IR extinction performance.

Investigation of Aerosol Number Concentration at Gosan Site in Jeju, Korea

The aerosol number concentration have measured with an aerodynamic particle sizer spectrometer(APS) at Gosan site in Jeju, Korea, from March 2010 to March 2011. And then the atmospheric aerosol number concentration, the temporal variation and the size distribution of aerosol number concentration have been investigated. The aerosol number concentration varies significantly from 748 particles/㎝ 3 to zero particles/㎝ 3 . The average number concentration in small size ranges are very higher than those in large size ranges. The number concentrations in the size range 0.25∼0.28 ㎛, 0.40∼0.45 ㎛ and 2.0∼2.5 ㎛ are about 84 particles/㎝ 3 , 2 particles/㎝ 3 and 0.4 particles/㎝ 3 , respectively. The number concentrations in range of larger than 7.5 ㎛ are below 0.001 particles/㎝ 3 . The seasonal variations in the number concentration for smaller particle(<1.0 ㎛) are not much, but the variations for larger particle are very evident. And strong amplitudes of diurnal variations of entire averaged aerosol number concentration are not observed. Size-fractioned aerosol number concentrations are dramatically decreased with increased particle size. The size-fractioned aerosol number concentrations in size range 0.8∼4.0 ㎛ during nighttime are evidently higher than during daytime, but similar levels are appeared in other size range. The seasonal differences in the size-fractioned number concentrations for smaller size range(<0.7 ㎛) are not observed, however, the remarkable seasonal differences are observed for larger size than 0.7 ㎛.

Analysis of Dust Aerosol by Using Dual-wavelength Lidar

Simulation of dust aerosol optical property is rather difficult, due to its extremely irregular shape, which often brings about difficulties in transforming its physical properties (such as size distribution) into optical properties (such as scattering phase function) in remote sensing retrieval and atmospheric radiation model. Some recent researches reveal that homogeneous spheroids seem to be an applicable optical model when dust particles are not much bigger than the wavelength, spheroids with reasonable shape distribution can simulate the scattering phase function of dust particles quite well. Based on the existed dual-wavelength lidar inversion algorithms, a modified method is proposed in the paper. Assuming the size distributions of dust aerosol can be modeled by bimodal lognormal distributions dominated by particles ranged in coarse mode, the size distributions and lidar ratios of dust aerosol at two wavelengths can be derived from dual-wavelength lidar measurement. By applying this algorithm to the data of dual-wavelength lidar at Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), preliminary results show that for the case of pure dust the retrieved size distribution agree with that observed by Aerodynamic Particle Sizer Spectrometer, and the derived mean lidar ratios are 45.7 ± 5.3 sr at 532 nm and 33.9 ± 1.5 sr at 1064 nm.

In vitro Evaluation of Dry Powder Inhaler Devices of Corticosteroid Preparations

Although investigations of the drug aerosols generated from inhaled corticosteroid (ICS) preparations and combined drug preparations provide basic information about inhalation therapy, many clinicians have one-sided data about the precision of drug aerosols from the manufacturer. The present study was conducted to analyze and compare the performances of dry powder inhaler (DPI) devices of ICS and combined drug preparations. The particle size of individual aerosols was measured according to the time-of-flight principle in terms of their aerodynamic diameter by using the aerodynamic particle sizer spectrometer Model 3321. Percent aerosolization was measured using only stage #0 and backup filters of the Andersen non-viable sampler model AN-200. The particle size distribution of aerosols generated from a Turbuhaler™ and Twisthaler™ showed a mono-modal distribution of less than 5 μm. In contrast, Diskus™ showed a polydisperse distribution, ranging from 0.5 to 20 μm. The percentages of DPI preparations converted into aerosols with a particle size less than 11 μm at a suction flow rate of 28.3 L/min were 5.7-6.2% for Diskus, 37.5-47.0% for Turbuhaler, and 19.8% for Twisthaler. At a suction flow rate of 60 L/min, the conversion percentages for DPI preparations into aerosols with a particle size less than 7.6 μm were 5.9-7.5%, 78.2-86.7%, and 43.5%, respectively. Because in vitro differences in the aerosolization among different DPI devices containing ICS and combined drug preparations were observed, prescribers of these preparations should consider whether the patients will benefit more from the treatment of the central airways versus the peripheral airways.

Improving the discrimination capability of bioaerosols using a dual-channel ultraviolet aerodynamic particle sizer spectrometer

We report on the results of laboratory evaluation of a dual-channel ultraviolet aerodynamic particle sizer spectrometer for real-time, continues monitoring of bio-aerosols. The detected fluorescence light was divided into two channels, simultaneously measuring the blue (400–500 nm) and green (500–600 nm) signal, which were corresponding to the fluorescence spectra of NAD(P)H and riboflavin, respectively. Primary results show the different fluorescence properties of the bacteria aerosols (Escherichia coli, Staphylococci and Bacillus subtilis var. niger spore) and the substrate (TSA eluate solutions, TSB and Nutrient broth). We demonstrated a promising method to improve the discrimination capability of bioaerosols from non-bioaerosol background components and to distinguish different types of bioaerosol particles.

Influence Factors on Particle Growth for On-line Aerosol Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

An evaporation/condensation flow cell was developed and interfaced with the matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometer for on-line bioaerosol detection and characterization, which allows matrix addition by condensation onto the laboratory-generated bioaerosol particles. The final coated particle exiting from the condenser is then introduced into the aerodynamic particle sizer spectrometer or home-built aerosol laser time-of-flight mass spectrometer, and its aerodynamic size directly effects on the matrix-to-analyte molar ratio, which is very important for MALDI technique. In order to observe the protonated analyte molecular ion, and then determine the classification of biological aerosols, the matrix-to-analyte molar ratio must be appropriate. Four experimental parameters, including the temperature of the heated reservoir, the initial particle size, its number concentration, and the matrix material, were tested experimentally to analyze their influences on the final particle size. This technique represents an on-line system of detection that has the potential to provide rapid and reliable identification of airborne biological aerosols.

Application of UVAPS to real-time detection of inactivation of fungal bioaerosols due to thermal energy

In this study, we investigate the capability of the ultraviolet aerodynamic particle sizer spectrometer (UVAPS) with respect to real-time detection of the inactivation (death) of fungal bioaerosols due to thermal energy. Developed to detect viable bioaerosols, the UVAPS was not expected to produce any signal for dead bioaerosols. However, the experimental results show that the UVAPS produces fluorescence signals from fungal bioaerosols inactivated by sub-seconds exposure to thermal energy. The UVAPS measurement was taken a few seconds after fungal bioaerosols were inactivated by a thermal stimulus. The application of the UVAPS to real-time detection of the death of fungal bioaerosols may be limited under the present experimental conditions.

A New Aerosol Flow System for Photochemical and Thermal Studies of Tropospheric Aerosols

For studying the formation and photochemical/thermal reactions of aerosols relevant to the troposphere, a unique, high-volume, slow-flow, stainless steel aerosol flow system equipped with UV lamps has been constructed and characterized experimentally. The total flow system length is 8.5 m and includes a 1.2 m section used for mixing, a 6.1 m reaction section and a 1.2 m transition cone at the end. The 45.7 cm diameter results in a smaller surface to volume ratio than is found in many other flow systems and thus reduces the potential contribution from wall reactions. The latter are also reduced by frequent cleaning of the flow tube walls which is made feasible by the ease of disassembly. The flow tube is equipped with ultraviolet lamps for photolysis. This flow system allows continuous sampling under stable conditions, thus increasing the amount of sample available for analysis and permitting a wide variety of analytical techniques to be applied simultaneously. The residence time is of the order of an hour, and sampling ports located along the length of the flow tube allow for time-resolved measurements of aerosol and gas-phase products. The system was characterized using both an “inert” gas (CO 2 ) and particles (atomized NaNO 3 ). Instruments interfaced directly to this flow system include a NO x analyzer, an ozone analyzer, relative humidity and temperature probes, a scanning mobility particle sizer spectrometer, an aerodynamic particle sizer spectrometer, a gas chromatograph-mass spectrometer, an integrating nephelometer, and a Fourier transform infrared spectrophotometer equipped with a long path (64 m) cell. Particles collected with impactors and filters at the various sampling ports can be analyzed subsequently by a variety of techniques. Formation of secondary organic aerosol from α-pinene reactions (NO x photooxidation and ozonolysis) are used to demonstrate the capabilities of this new system.

Electrospray-Assisted Ultraviolet Aerodynamic Particle Sizer Spectrometer for Real-time Characterization of Bacterial Particles

The ultraviolet aerodynamic particle sizer (UVAPS) spectrometer is a novel, commercially available aerosol counter for real-time, continuous monitoring of viable bioaerosols based on the fluorescence induced from living microorganisms. For aerosolization of liquid-based microorganisms, general aerosolization methods such as atomization or nebulization may not be adequate for an accurate and quantitative characterization of the microorganisms because of the formation of agglomerated particles. In such cases, biological electrospray techniques have an advantage because they generate nonagglomerated particles, attributable to the repulsive electrical forces among particles with unipolar charges. Biological electrosprays are quickly gaining potential for the detection and control of living organisms in applications ranging from mass spectrometry to developmental microbiology. In this study, we investigated the size distribution, total concentration, and fluorescence percentage of bacterial particles in a real-time manner by electrospray-assisted UVAPS. A suspension containing Escherichia coli as a test microorganism was sprayed in a steady cone-jet mode using a specially designed electrospray system with a point-to-orifice-plate configuration based on charge-reduced electrospray size spectrometry. With the electrospray process, 98% of the total E. coli particle number concentration had a size of <1 mum and the geometric mean diameter was 0.779 mum, as compared with the respective values of 78% and 0.907 mum after nebulization. The fractions of fluorescence responsive particles and of particles that contained viable organisms in culture were 12% and 7%, respectively, from the electrospray process and 34% and 24% from nebulization. These results demonstrate that (1) the presence of agglomerated particles can lead to markedly overestimated fluorescence and culturability percentages compared with the values obtained from nonagglomerated particles, and (2) electrospray-assisted UVAPS can provide more accurate and quantitative real-time characterization of liquid-based microorganisms, owing to the generation of nonagglomerated particles.

Effect of illumination intensity and light application time on secondary organic aerosol formation from the photooxidation of α-pinene

Secondary organic aerosol (SOA) formation from hydroxyl radical (OH*) initiated photooxidation of alpha-pinene was investigated in a home-made smog chamber. The size distribution of SOA particles was measured using aerodynamic particle sizer spectrometer. The effects of illumination intensity and light application time on SOA formation for alpha-pinene were evaluated. Experimental results show that the concentration of SOA particles increased significantly with an increasing of illumination intensity, and the light application time, the concentration, and the size of SOA particles were also increased. In addition, the factors influencing the formation of SOA were discussed. In addition, this article compared the effect of alpha-pinene with that of toluene, and discussed the contribution of alpha-pinene to SOA formation.

Fine and Ultrafine Particle Characterization and Modeling in High-Speed Milling of 6061-T6 Aluminum Alloy

In this study, an experimental investigation was carried out on fine and ultrafine metallic dust emission during high-speed milling of 6061-T6 aluminum alloy in wet and dry conditions. Measurements of dust emission were conducted using a scanning mobility particle sizer spectrometer and an aerodynamic particle sizer spectrometer. These instruments were used to characterize particles in the micrometer and the nanometer size ranges. It was confirmed that the machining process produces nanoparticles as small as 10 nm and that the characteristics of the generated nanoparticles are not significantly influenced by the cutting conditions. The cutting forces and chip compression ratio were measured to validate the proposed dust generation model based on an energy approach. Good agreement was observed between the model and the experimental measurements for the investigated conditions. It was demonstrated that the majority of generated dust is caused by deformations in the primary shear zone. In addition, the percentage of generated dust is significantly influenced by deformation conditions in the chip formation zone. It was found that high cutting speeds could reduce the percentage of the generated particles during the milling process.

P.451 VEGF in the TMJ related to the clinical outcome

Secondary organic aerosol (SOA) formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS), respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e., PM2.5), and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed.