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Maki, Teruya,Ishikawa, Akira,Kobayashi, Fumihisa,Kakikawa, Makiko,Aoki, Kazuma,Mastunaga, Tomoki,Hasegawa, Hiroshi,Iwasaka, Yasunobu Korean Society for Atmospheric Environment 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.3
Atmospheric aerosol deposition caused by Asian dust (KOSA) events provide nutrients, trace metals, and organic compounds over the Pacific Ocean that enhance ocean productivity and carbon sequestration and, thus, influence the atmospheric carbon dioxide concentrations and climate. Using dust particles obtained from the snow layers on Mt. Tateyama and the surface sand of Loess Plateau in incubation experiments with natural seawater samples on a shipboard, we demonstrate that dust-particle additions enhanced the bacterial growth on the first day of incubation. Gram-positive bacterial group and alpha-proteobacteria were specifically detected form seawater samples including the mineral particles. Although the remarkable dynamics of trace elements and nutrients depend on dust-particle additions, it is possible that organic compounds present in the mineral particles or transported microbial cells could also contribute to an increase in the quantities of bacteria. The chlorophyll concentrations at fractions of every size indicated a similar pattern of change between the seawater samples with and without the dust-particle additions. In contrast, the chlorophyll measurement using submersible fluorometer revealed that the dynamics of phytoplankton composition were influenced by the dust-particles treatments. We conclude that the phytoplankton that uses the bacterial products would increase their biomass. We show that KOSA deposition can potentially alter the structures of bacterial communities and indirectly influence the patterns of marine primary production in the Pacific Ocean.
Teruya Maki,Akira Ishikawa,Fumihisa Kobayashi,Makiko Kakikawa,Kazuma Aoki,Tomoki Mastunaga,Hiroshi Hasegawa,Yasunobu Iwasaka 한국대기환경학회 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.3
Atmospheric aerosol deposition caused by Asian dust (KOSA) events provide nutrients, trace metals, and organic compounds over the Pacific Ocean that enhance ocean productivity and carbon sequestration and, thus, influence the atmospheric carbon dioxide concentrations and climate. Using dust particles obtained from the snow layers on Mt. Tateyama and the surface sand of Loess Plateau in incubation experiments with natural seawater samples on a shipboard,we demonstrate that dust-particle additions enhanced the bacterial growth on the first day of incubation. Gram-positive bacterial group and alpha-proteobacteria were specifically detected form seawater samples including the mineral particles. Although the remarkable dynamics of trace elements and nutrients depend on dust-particle additions, it is possible that organic compounds present in the mineral particles or transported microbial cells could also contribute to an increase in the quantities of bacteria. The chlorophyll concentrations at fractions of every size indicated a similar pattern of change between the seawater samples with and without the dust-particle additions. In contrast, the chlorophyll measurement using submersible fluorometer revealed that the dynamics of phytoplankton composition were influenced by the dust-particles treatments. We conclude that the phytoplankton that uses the bacterial products would increase their biomass. We show that KOSA deposition can potentially alter the structures of bacterial communities and indirectly influence the patterns of marine primary production in the Pacific Ocean.
Controlled Cationic Polymerization of Sulfide-Containing Vinyl Ethers
Takeshi Namikoshi,Yuhei Watanabe,Ayaka Kaneda,Kazuma Ishikawa,Shinji Watanabe,Miki Murata 한국고분자학회 2022 Macromolecular Research Vol.30 No.1
The living cationic polymerizations of sulfide-containing vinyl ethers, namely, alkyl-sulfide-containing 2-(ethylthio)ethyl vinyl ether (ESEVE) and arylsulfide- containing 2-(phenylthio)ethyl and 2-[4-(methylthio)phenoxy]ethyl vinyl ethers (PSEVE and MSPEVE, respectively), were examined using HCl/ZnCl2, 1-(isobutoxy)ethyl acetate (IBEA)/Et1.5AlCl1.5, and IBEA /Et1.5AlCl1.5/SnCl4 as initiators. The polymerization of ESEVE terminated at a 35% monomer conversion, and a high-molecular-weight polymer was not obtained; instead, the nucleophilicity of the sulfur moiety in ESEVE led to cyclization, forming five-membered ring sulfonium species. In contrast, the side reactions were suppressed when PSEVE was used, which has a less-nucleophilic sulfur moiety on its benzene ring, and polymerization proceeded to an 88% conversion, affording a high-molecular-weight polymer with a narrow molecular weight distribution (Mw= 12,500, Mw/Mn = 1.18). Furthermore, cyclic sulfonium was not produced during the polymerization of MSPEVE, in which the sulfur atom was farther from the generated carbocation; the polymerization proceeded quantitatively producing a high-molecular-weight polymer with a narrow molecular weight distribution, despite the short lifetime of the growing species. In particular, a high-molecular-weight polymer with the narrowest distribution (Mw= 13,500, Mw/Mn = 1.08) was obtained when SnCl4 was used as the Lewis acid.