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Hayakawa, Kazuichi,Tang, Ning,Kameda, Takayuki,Toriba, Akira Korean Society for Atmospheric Environment 2007 Asian Journal of Atmospheric Environment (AJAE) Vol.1 No.1
Hazardous polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) are mainly originated from imperfect combustion of fossil fuels such as petroleum and coal. The consumptions of not only petroleum but also coal have been increasing in the East Asian countries. This review describes the result of international collaboration research concerning characteristics and major contributors of atmospheric PAHs and NPAHs in cities in Japan, Korea, China and Russia. We collected airborne particulates in ten cities in the above countries and six PAHs and eleven NPAHs were determined by HPLC methods using fluorescence and chemiluminescence detections. The total PAH concentrations were much higher in Chinese cities (Fushun, Tieling, Shenyang and Beijing) than those in other cities (Vladivostok, Busan, Kanazawa, Kitakyushu, Sapporo and Tokyo). The total NPAH concentrations were also higher in Chinese cities than those in the other cities. The [NPAH]/[corresponding PAH] ratios are much larger in diesel-engine exhaust particulates than those in coal-burning particulates. The [1-nitropyrene]/[pyrene] ratio of airborne particulates was much smaller in the four Chinese cities, suggesting that coal combustion systems such as coal heaters were the main contributors. On the other hand, the ratios were larger in Korean and Japanese cities, suggesting the large contribution of diesel-engine vehicles.
Atmospheric Polycyclic and Nitropolycyclic Aromatic Hydrocarbons in an Iron-manufacturing City
Hayakawa, Kazuichi,Tang, Ning,Morisaki, Hiroshi,Toriba, Akira,Akutagawa, Tomoko,Sakai, Shigekatsu Korean Society for Atmospheric Environment 2016 Asian Journal of Atmospheric Environment (AJAE) Vol.10 No.2
Total suspended particulates (TSP) in the atmosphere were collected for 2 weeks during winter in Muroran, Hokkaido, Japan, a typical iron-manufacturing city. The concentrations of polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) in TSP were determined by high-performance liquid chromatography (HPLC) using fluorescence and chemiluminescence detectors, respectively. No relationship was observed between the atmospheric PAH and NPAH concentration, or the atmospheric PAH and TSP concentration. However, there was a tendency that the atmospheric PAH concentration was higher when the wind blew from the coke-oven plant. Furthermore, the concentration ratios of 1-nitropyrene to pyrene, which is a suitable indicator of the contribution made by automobiles and coal combustion systems to urban air particulates, were smaller in Muroran and the values were close to those observed in particulates from coal combustion systems. Therefore, these results show that the PAH and NPAH compositions for Muroran are characteristic of an iron-manufacturing city.
Anti-Cancer Effects of Green Tea by Either Anti- or Pro-Oxidative Mechanisms
Hayakawa, Sumio,Saito, Kieko,Miyoshi, Noriyuki,Ohishi, Tomokazu,Oishi, Yumiko,Miyoshi, Mamoru,Nakamura, Yoriyuki Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.4
Tea derived from the leaves and buds of Camellia sinensis (Theaceae) is consumed worldwide. Green tea contains various components with specific health-promoting effects, and is believed to exert protective effects against diseases including cancer, diabetes and hepatitis, as well as obesity. Of the various tea components, the polyphenol catechins have been the subject of extensive investigation and among the catechins, (-)-epigallocatechin gallate has the strongest bioactivity in most cases. Our research group has postulated that hepatocyte nuclear factor-$4{\alpha}$, sterol regulatory element-binding proteins, and tumor necrosis factor-${\alpha}$ are targets of green tea constituents including (-)-epigallocatechin gallate for their anti-diabetes, anti-obesity, and anti-hepatitis effects, respectively. Published papers were reviewed to determine whether the observed changes in these factors can be correlated with anti-cancer effects of green tea. Two major action mechanisms of (-)-epigallocatechin gallate have been proposed; one associated with its anti-oxidative properties and the other with its pro-oxidative activity. When reactive oxygen species are assumed to be involved, our findings that (-)-epigallocatechin gallate downregulated hepatocyte nuclear factor-$4{\alpha}$, sterol regulatory element-binding proteins, and tumor necrosis factor-${\alpha}$ may explain the anti-cancer effect of green tea as well. However, further studies are required to elucidate which determinant directs (-)-epigallocatechin gallate action as an anti-oxidant or a pro-oxidant for favorable activity.
Short-Lived Radioisotope Tc98 Synthesized by the Supernova Neutrino Process
Hayakawa, Takehito,Ko, Heamin,Cheoun, Myung-Ki,Kusakabe, Motohiko,Kajino, Toshitaka,Usang, Mark D.,Chiba, Satoshi,Nakamura, Ko,Tolstov, Alexey,Nomoto, Ken’ichi,Hashimoto, Masa-aki,Ono, Masaomi,Kawano, American Physical Society 2018 Physical Review Letters Vol.121 No.10
Hayakawa, Kazuhide,Pham, Loc-Duyen D,Seo, Ji Hae,Miyamoto, Nobukazu,Maki, Takakuni,Terasaki, Yasukazu,Sakadž,ić,, Sava,Boas, David,van Leyen, Klaus,Waeber, Christian,Kim, Kyu-Won,Arai, Ken,L SAGE Publications 2016 Journal of cerebral blood flow and metabolism Vol.36 No.4
<P> There are numerous barriers to white matter repair after central nervous system injury and the underlying mechanisms remain to be fully understood. In this study, we propose the hypothesis that inflammatory macrophages in damaged white matter attack oligodendrocyte precursor cells via toll-like receptor 4 signaling thus interfering with this endogenous progenitor recovery mechanism. Primary cell culture experiments demonstrate that peritoneal macrophages can attack and digest oligodendrocyte precursor cells via toll-like receptor 4 signaling, and this phagocytosis of oligodendrocyte precursor cells can be inhibited by using CD200-Fc to downregulate toll-like receptor 4. In an in vivo model of white matter ischemia induced by endothelin-1, treatment with CD200-Fc suppressed toll-like receptor 4 expression in peripherally circulating macrophages, thus restraining macrophage phagocytosis of oligodendrocyte precursor cells and leading to improved myelination. Taken together, these findings suggest that deleterious macrophage effects may occur after white matter ischemia, whereby macrophages attack oligodendrocyte precursor cells and interfere with endogenous recovery responses. Targeting this pathway with CD200 may offer a novel therapeutic approach to amplify endogenous oligodendrocyte precursor cell-mediated repair of white matter damage in mammalian brain. </P>
Hayakawa Teruaki,Kouketsu Takayuki,Kakimoto Masa-alki,Yokoyama Hideaki,Horiuchi Shin The Polymer Society of Korea 2006 Macromolecular Research Vol.14 No.1
A novel fabrication of the patterned surfaces in the polymer films was demonstrated by using the self-organizing character of the block copolymers of polystyrene-b-oligothiophenes and polystyrene-b-aromatic amide dendron. Hexagonally arranged open pores with a micrometer-size were spontaneously formed by casting the polymer solutions under a moist air flow. The amphiphilic character of the block copolymers played the crucial role as a surfactant to stabilize the inverse emulsion of water in the organic solvent, and subsequently the aggregated structure of the hydrophilic oligothiophene or aromatic amide dendron segments remained on the interiors of the micropores. The chemical composition on the top of the surface of the microporous films was characterized by energy-filtering transmission electron microscopy (EFTEM) or a time-of-flight secondary ion mass spectrometer (ToF-SIMS). The characterizations clearly indicated that the patterned surfaces in the self-organized block copolymer films with the hexagonally ordered microporous structures were fabricated in a single step.
The Trade Effect of Non-tariff Measures in a Comprehensive Trade Agreement
Hayakawa Kazunobu,Jongwanich Juthathip,Kohpaiboon Archanun 한국국제경제학회 2024 International Economic Journal Vol.38 No.1
The aim of this study is to quantify the trade effects of the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), which is considered to be a comprehensive trade agreement. To this end, we estimate the gravity equation for worldwide trade and introduce applied tariffs into this equation to differentiate between the trade effects of tariff reduction and non-tariff measure (NTM) changes. Our gravity equation results indicate that the trade effect of NTM changes under the CPTPP is insignificant on average and negative for most products. We also estimate the gravity equation for foreign direct investment (FDI) and find some evidence that the CPTPP increased FDI by a statistically significant amount. Thus, the NTM changes in the CPTPP may increase FDI, rather than trade, among member countries.