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Kulkarni P.,Centers for Disease Control and Prevention | Qi C.,Centers for Disease Control and Prevention | Fukushima N.,Kanomax Japan Inc.
Aerosol Science and Technology | Year: 2016

We describe development of a portable aerosol mobility spectrometer (PAMS) for size distribution measurement of submicrometer aerosol. The spectrometer is designed for use in personal or mobile aerosol characterization studies and measures approximately 22.5×22.5×15 cm and weighs about 4.5 kg including the battery. PAMS uses electrical mobility technique to measure number-weighted particle size distribution of aerosol in the 10–855 nm range. Aerosol particles are electrically charged using a dual-corona bipolar corona charger, followed by classification in a cylindrical miniature differential mobility analyzer. A condensation particle counter is used to detect and count particles. The mobility classifier was operated at an aerosol flow rate of 0.05 L/min, and at two different user-selectable sheath flows of 0.2 L/min (for wider size range 15–855 nm) and 0.4 L/min (for higher size resolution over the size range of 10.6–436 nm). The instrument was operated in voltage stepping mode to retrieve the size distribution in approximately 1–2 min. Sizing accuracy and resolution were probed and found to be within the 25% limit of NIOSH criterion for direct-reading instruments. Comparison of size distribution measurements from PAMS and other commercial mobility spectrometers showed good agreement. The instrument offers unique measurement capability for on-person or mobile size distribution measurement of ultrafine and nanoparticle aerosol. © 2016, Taylor & Francis. All rights reserved.

Ogi T.,Hiroshima University | Balgis R.,Hiroshima University | Okuyama K.,Hiroshima University | Tajima N.,Kanomax Japan Inc. | Setyawan H.,Sepuluh Nopember Institute of Technology
AIChE Journal | Year: 2013

Platinum-deposited titanium nitride (Pt/TiN) nanoparticle aggregates with high porosities were successfully prepared via a self-assembly-assisted spray pyrolysis method. The addition of formic acid (HCOOH) had a significant influence on the process, promoting the simultaneous formation of metallic Pt and reduction on the surface of the TiN support material. Complete reduction of the Pt/TiN nanoparticle aggregates improved the catalytic activity. The electrochemical surface area (ECSA) of Pt/TiN with HCOOH (Pt/TiNw/HCOOH) was 87.15 m2/g-Pt, which was higher than that of Pt/TiN without HCOOH (Pt/TiNw/o-HCOOH). The catalytic durability of Pt/TiNw/HCOOH was twice that of Pt/TiNw/o-HCOOH. An effective strategy for obtaining carbon-free catalysts with high activities and durabilities was identified. © 2013 American Institute of Chemical Engineers.

Rawat V.K.,University of Minnesota | Buckley D.T.,University of Minnesota | Kimoto S.,University of Minnesota | Lee M.-H.,Korea Institute of Industrial Technology | And 2 more authors.
Journal of Aerosol Science | Year: 2016

We developed and applied a data inversion routine to determine the number based size-mass distribution function (the two dimensional distribution function) from tandem differential mobility analyzer-aerosol particle mass analyzer (DMA-APM) measurements. The two dimensional distribution function is expressed in units of particle number concentration per unit mobility diameter per unit particle mass. It can be used to directly calculate the number based size distribution (commonly determined using DMA measurements) or the mass based size distribution (commonly inferred from impactor measurements). The inversion routine utilizes the Twomey-Markowski algorithm and is applied in this study to DMA-APM measurements of sodium chloride, cesium iodide, and ammonium sulfate particles in the 30-200. nm mobility diameter range, as well as acetylene flame generated soot aggregates in the 40-350. nm range. To utilize the inversion routine, the APM transfer function must be known a priori. Here it is computed using a modified version of the Ehara (uniform flow) model, with a transmission correction factor inferred from measurements. For the three examined salt particle types, visual representation of the two dimensional distribution function reveals that at a given mobility diameter, particles have very narrow mass distributions, with the peak masses in good agreement with predictions based on bulk salt densities. However, for soot particles, extremely broad distributions are observed. Soot measurements are compared to predictions for quasifractal aggregates in the transition regime; this comparison suggests that aggregates with fractal dimensions ranging from 1.4 to 2.5 are all generated in the same system. Finally, we determine the two-dimensional distribution function for a mixture of ammonium sulfate and soot particles, demonstrating that these two particle populations are separable from one another via mobility-mass analysis. © 2015 Elsevier Ltd.

Akiguchi S.,National Institute of Technology, Toyama College | Ishida H.,National Institute of Technology, Toyama College | Andoh T.,University of Toyama | Hachiga T.,National Institute of Technology, Toyama College | And 4 more authors.
Measurement Science and Technology | Year: 2012

Our research goal is to carry out two-dimensional (2D) and three-dimensional (3D) measurements of the velocity distribution within a single vessel. We modified a non-invasive beam laser Doppler velocimeter using near-infrared light, and linearized the laser to carry out simultaneous multipoint measurements. We also scanned the measurement line in the direction of depth to allow 3D imaging of vascular blood flow in opaque areas in vivo. We used micro multipoint laser Doppler velocimetry (LDV) and a device with improved spatial resolution from 250 to 125 μm. We compared actual and calculated values using a rotating disk with an attached microwire. To demonstrate the effectiveness of the proposed system, blood flowing at a constant rate through a glass capillary and the velocity distribution of flow in the capillary were measured and mapped. The average flow velocity was calculated from the cross-sectional area and flow rate in the glass capillary, and we compared the calculated and measured values. To obtain an image of blood flow velocity in vivo, we measured both 2D and 3D flow velocity distributions in mouse mesenteric vessels. © 2012 IOP Publishing Ltd.

Eryu K.,Kanazawa University | Seto T.,Kanazawa University | Furuuchi M.,Kanazawa University | Otani Y.,Kanazawa University | And 2 more authors.
Journal of Chemical Engineering of Japan | Year: 2011

Sampling of particles smaller than 100 nm is of great concern for assessing the adverse health effects of airborne nanoparticles in both atmosphere and workplaces. Inertial filter (IF) is a new application of air filter, which is recently developed by the present authors to classify nanoparticles by passing aerosol through an air filter at a high filtration velocity. In the present work, we investigated the effects of fiber packing density and particle deposit on classification performance of IF to achieve 50% cut-off diameter of 100 nm for sampling nanoparticles. Unwoven stainless steel (SUS) fiber mat with diameter of 8 μm is used as a filter medium. It was found that, in inertial regime, the collection efficiency changes markedly with the packing density due to the interactions of neighboring fibers. As a result, by adjusting the filtration velocity to achieve 50% cut-off diameter of 100 nm, IF with various packing densities had almost the same classification performance, and a compressed filter is advantageous because it had a lower pressure drop. The influence of loaded particles on the classification performance was also investigated. It was found that, up to the collected particle mass of 1 mg, the effect of dust load is not significant. Therefore IF with a higher packing density is superior in achieving 50% cut-off diameter of 100 nm from the viewpoints of both initial and dust-loaded classification performance. © 2011 The Society of Chemical Engineers, Japan.

Furuuchi M.,Kanazawa University | Eryu K.,Kanazawa University | Nagura M.,Kanazawa University | Hata M.,Kanazawa University | And 6 more authors.
Aerosol and Air Quality Research | Year: 2010

This paper describes the design and evaluation of an ambient air sampler consisting of a four-stage impactor and an inertial filter, for collecting various size fractions, including nano-particles, in a short sampling period. Impactor stages of PM10/PM2.5/PM1/PM 0.5 were successfully devised with a reasonable accuracy in terms of cutoff size and slope of the collection efficiency curves. The designed inertial filter had an aerodynamic cutoff size of dp50 ~65 nm with a satisfactory sharpness in classification. The total pressure drop of the sampler (hereinafter referred to as a "Nanosampler") was ~30 kPa at a flow rate of 40 L/min. The developed Nanosampler has advantages over currently available samplers such as LPI and nano-MOUDI, in terms of portability and loss of semi-volatile components in ultrafine particles by evaporation at a reduced pressure. Furthermore, the size distributions of the ambient particles measured with the Nanosampler compared favorably with those measured by the conventional instruments that are currently available on the market. © Taiwan Association for Aerosol Research.

Tajima N.,Kanomax Japan Inc. | Sakurai H.,Japan National Institute of Advanced Industrial Science and Technology | Fukushima N.,Kanomax Japan Inc. | Ehara K.,Japan National Institute of Advanced Industrial Science and Technology
Aerosol Science and Technology | Year: 2013

A compact aerosol particle mass analyzer (APM) of which the size of the classifier was significantly reduced than that of the first commercial model (Kanomax Model 3600) was developed. Firstly, requirements for desired performance in classifying particle mass were set forth. Secondly, a theoretical framework for the design parameters of anAPMthat satisfies the requirements was formulated. Thirdly, the design parameters were determined that satisfies the requirementswhile reducing the instrument size. The requirements include the condition that the classification range covers from 0.001 to 1000 fg (approximately 12 to 1200 nm in size for spherical particles having the density of 1 g/cm3), and the condition that both the classification resolution and particle penetration in this mass range are higher than certain specified values. A prototype having the design parameters determined according to this theoretical framework was constructed, and its performance was evaluated experimentally. The external dimensions of the electrodes of the compact APM are approximately 140 mm in length and 60 mm in diameter. It was confirmed that the performance of the compact APM operated at the aerosol flow rate of 0.3 L/min was comparable to that of the Model 3600 APM operated at 1 L/min. Because of the reduced size and of the resultant improved portability, it is expected that the compact APM is readily applicable to field measurements. Copyright © American Association for Aerosol Research.

Kim K.H.,Saitama University | Sekiguchi K.,Saitama University | Kudo S.,Saitama University | Sakamoto K.,Saitama University | And 4 more authors.
Aerosol and Air Quality Research | Year: 2010

A sampler using inertial fibrous filters (INF) has been recently developed for ultrafine particle collection by impaction and filtration. This new sampler has a low pressure drop (20-30 kPa) and can separate particles smaller than 0.1 μm with a high sampling flow rate (40 L/min). In this study, sampling performance of the INF sampler was evaluated in comparison with a reference sampler in the field as well as in the laboratory and the possible sulfate ion loss when using aluminum substrates for ion extraction in ultrasonic bath was discovered and investigated. When sampling ultrafine particles (Dp ≤ 0.1 μm) such as carbonaceous and ionic species both in the field and in the laboratory, the performance of the INF sampler was similar to that of a reference sampler despite differences of sampling mechanism, cut-point diameter, and substrate proving that the INF sampler can be an alternative for ultrafine particle collection. Underestimation of sulfate concentration appeared to be unavoidable in ultrasonic extractions from aluminum substrates regardless of whether the extraction time was 30 or 90 min. The average sulfate loss during aluminum filter extraction was 45% (± 12%; min: 12%; max: 94%). Therefore, ultrasonic extraction from aluminum filters should be avoided to obtain unbiased measurements of sulfate concentration in ambient air or other ion extraction methods should be considered to minimize sulfate loss (dissolution of aluminum ions) from aluminum filters with sufficient extraction efficiency of ionic species. The results of this study indicate that the performance of the INF sampler is almost similar to that of the nano-MOUDI sampler for ultrafine particle collection, while advantageous in terms of convenience, and analysis. Furthermore, the INF sampler can collect amounts of ultrafine particles that are sufficient for chemical analysis in a relatively short time, and the particles can be uniformly collected with a quartz fiber filter. © Taiwan Association for Aerosol Research.

Tajima N.,Kanomax Japan Inc. | Fukushima N.,Kanomax Japan Inc. | Ehara K.,Japan National Institute of Advanced Industrial Science and Technology | Sakurai H.,Japan National Institute of Advanced Industrial Science and Technology
Aerosol Science and Technology | Year: 2011

We investigated, theoretically, the mass range in which an aerosol particle mass analyzer (APM) can be used for classification, and how the APM classification performance can be optimized. We listed factors that set limits to the APM, which were constraints of the rotation speed and the voltage, as well as requirements on the APM classification performance parameter, λ, that guarantee at least minimal performance in both resolution and penetration. We introduced the APM operation diagram, which is a tool to visualize the limits and mass range. We proposed to operate the APM that was considered in this study with the λ value set within the range from 0.25 to 0.5 for optimum classification performance by balancing both resolution and penetration. The mass range for the APM, with the λ value maintained between 0.25 and 0.5, was calculated to be from 0.003 to 2000 fg, which corresponds to the diameter range from 20 to 1600 nm for the density of 1 g/cm 3. To verify the validity of the mass range and the idea of the optimized operation, we carried out experiments on an APM with polystyrene and sodium-chloride particles that were classified by electrical mobility. We found that the APM was able to provide bell-shaped spectra down to 12 nm, and was able to perform mass classification with an accuracy better than 5% down to 50 nm. Underestimation of mass and reduction of resolution and penetration were observed at sizes smaller than about 30 nm. © American Association for Aerosol Research.

Kitagawa K.,Aichi Institute of Technology | Ishiguro F.,Aichi Institute of Technology | Abe A.,ITOCHU Techno Solutions Corporation | Tanaka Y.,Kanomax Japan Inc.
Science and Technology of Energetic Materials | Year: 2012

Underwater shock wave passing through water and silicone oils is investigated in experimentally and numerically. The present work was conducted to study overpressure history, oscillation cycle and visualization of the collapsing gas bubble in visco-elastic fluids. The gas bubble size and repeated cycle strongly depend on the fluid kinetic viscosity, charge depth and sonic speed in medium. ΔP max in silicone oils decrease to about 41-47% of water value. Numerical results simulate well the experimental ones in bubble motion and jet in a downward flow.

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