Shuichi Hasegawa

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The radiocarbon ((14)C) of total carbon (TC) in atmospheric fine particles was measured at 6 h or 12 h intervals at two sites, 50 and 100 km downwind from Tokyo, Japan (Kisai and Maebashi) in summer 2007. The percent modern carbon (pMC) showed clear diurnal variations with minimums in the daytime. The mean pMC values at Maebashi were 28 ± 7 in the daytime(More)
The number concentration and number size distributions of ultrafine particles were measured with a Scanning Mobility Particle Sizer (SMPS) at a roadside in early autumn and winter, and the results are discussed with regard to the contribution of traffic activity and meteorological conditions. The number concentration of the <50 nm fraction increased in the(More)
Diurnal variations of fossil secondary organic carbon (SOC) and nonfossil SOC were determined for the first time using a combination of several carbonaceous aerosol measurement techniques, including radiocarbon (¹⁴C) determinations by accelerator mass spectrometry, and a receptor model (chemical mass balance, CMB) at a site downwind of Tokyo during the(More)
A method is described for characterization of size-resolved particles including the nanoparticles fraction with a diameter of 29-58 nm in roadside atmosphere. The method is based on thermal desorption (TD) of a sample followed by comprehensive two-dimensional gas chromatography (GC x GC) with novel detection capabilities, including high resolution(More)
Aerosol samples in the urban atmosphere of Kumamoto (32 degrees 48'N, 134 degrees 45'E) in southwestern Japan were collected onto aluminum foil strips. Parts of the samples were heated to 550 degrees C in pure helium gas, and oxygen (2%)-helium (98%) mixture gas. Particles in unheated and heated parts were characterized individually by their morphology and(More)
We developed an exposure estimation model for an epidemiological study on the effect of traffic-related air pollutants on respiratory diseases. The model estimates annual average outdoor concentration of nitrogen oxides (NOx) and elemental carbon (EC). The model is composed of three nested plume dispersion type submodels treating different spatial scales(More)
We report a case of simultaneous right and left coronary occlusion during percutaneous coronary intervention in the right coronary artery. An aortocoronary dissection induced by the forceful manipulation extended from the right to left sinus of Valsalva and occluded the ostia of both coronary arteries. The patient suffered cardiogenic shock and ventricular(More)
Atmospheric nanoparticles (<0.050 microm) have caused great concern recently due to their potential to affect human health. However, little is known about the chemical composition, sources, and atmospheric behavior of atmospheric nanoparticles. Although gas chromatography/mass spectrometry (GC/MS) after solvent extraction is a commonly used and powerful(More)