Time filter

Source Type

Osaka, Japan

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. Source

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. Source

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. Source

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. Source

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. Source

Discover hidden collaborations