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-poly (AAc) membrane for selective separation of metal ionsHasegawa, Shin; Ohashi, Hitoshi; Maekawa, Yasunari; Katakai, Ryoichi*; Yoshida, Masaru
Polymer Journal, 41(7), p.533 - 540, 2009/07
Times Cited Count：3 Percentile：11.53(Polymer Science)We investigated the permeation behavior of Li over Co and Ni ions through thermo- and pH-responsive gel membranes. The gel membranes were synthesized by 
-ray grafting of pH-responsive poly (acrylic acid) (AAc) onto a thermo-responsive polymer gel of acryloyl-L-proline methyl ester (A-ProOMe). The permeation constant of Li ions is 3.5 and 2.8 times higher than those of Co and Ni ions at 30 
C in a pH 6.0. The most appropriate temperature and pH through the 15% grafted membrane were 30 C and pH 6.0. The adjacencies of the carboxyl groups of poly (AAc) surrounded by thermo-responsive poly (A-ProOMe) matrix must be decisive for the selective Li ion permeability. From the microscopic structures using SEM and the distributions of Co and Ni ions by EDS analysis, we confirmed that the structures formed by the flexible grafted chains of the carboxyl groups onto the thermo-response gel membrane are significant for the selective permeation of Li ion.
enolaseOku, Hiroyuki*; Yamada, Keiichi*; Kobayashi, Kyoko*; Katakai, Ryoichi*; Ashfaq, M.*; Hanaoka, Hirofumi*; Iida, Yasuhiko*; Endo, Keigo*; Hasegawa, Shin; Maekawa, Yasunari; et al.
Peptide Science 2008, p.439 - 442, 2009/03
Malaria is the major cause of mortality and morbidity in the tropical and subtropical regions in the world. Our previous studies have shown that a series of partial peptides of a Plasmodium falciparum enolase have antigenic reactivity against patients' sera. In this paper, we wish to report nano-encapsulation of a synthetic antigen into bioabsorbable polymer particles and their releasing studies in vitro and in vivo.
-ray preirradiation methodKimura, Yosuke; Asano, Masaharu; Chen, J.; Maekawa, Yasunari; Katakai, Ryoichi*; Yoshida, Masaru
Radiation Physics and Chemistry, 77(7), p.864 - 870, 2008/07
Times Cited Count：32 Percentile：87.37(Chemistry, Physical)We prepared polymer electrolyte membranes (PEMs) by post-polymerization of styrene (St) with divinylbenzene (DVB) into poly(ethylene-co-tetrafluoroethylene) (ETFE) films in the presence of toluene, isopropyl alcohol (iPrOH), tetrahydrofuran (THF), and tetrachloroethane (TCE) after pre--irradiation followed by a sulfonation. In the case of iPrOH, the grafting yield showed a marked increase compared with those of other solvents. On the other hand, it was found that the durability time of a PEM prepared in the presence of tetrachloroethane was 2 times higher than that in the presence of toluene.
Kimura, Yosuke*; Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Katakai, Ryoichi*; Yoshida, Masaru
Nuclear Instruments and Methods in Physics Research B, 263(2), p.463 - 467, 2007/10
Times Cited Count：18 Percentile：75.3(Instruments & Instrumentation)Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams, followed by pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent were examined to determine their effect on the proton conductivity of the resultant membranes. It was found that the polymer electrolyte membrane prepared by grafting the styrene monomer in a mixture of isopropanol and water to the ETFE film with a ion-beam irradiation fluence was a highly anisotropic proton-conducting material, as the proton conductivity was 3 or more times higher in the thickness direction than in the surface direction of the membrane.
Yamaki, Tetsuya; Tsukada, Junichi; Asano, Masaharu; Katakai, Ryoichi*; Yoshida, Masaru
Journal of Fuel Cell Science and Technology, 4(1), p.56 - 64, 2007/02
Times Cited Count：21 Percentile：45.69(Electrochemistry)PEFC applications will require that the ion exchange membranes have a high ion exchange capacity and reasonable chemical stability. We prepared novel ion exchange membranes by the radiation-induced graft copolymerization of styrene and bis(vinyl phenyl)ethane (BVPE) into crosslinked polytetrafluoroethylene (cPTFE) films and subsequent sulfonation and then investigated their stability in an oxidizing environment and water uptake. In contrast to divinylbenzene (DVB), the degree of grafting of styrene/BVPE increased in spite of high crosslinker concentrations in the reacting solution (up to 70 mol%). Complete sulfonation of the crosslinked graft chains resulted in the preparation of the membranes with a large ion exchange capacity reaching 2.5 meq/g, which exceeded the performance of Nafion. The BVPE-crosslinked membranes exhibited higher durability in a 3% aqueous solution of H
O at 60 C and decreased water uptake compared to the non-crosslinked one. These undoubtedly mean a profound effect of BVPE on PEFC performances of the membranes.
Hiroki, Akihiro; Maekawa, Yasunari; Katakai, Ryoichi*; Yamashita, Takashi*; Muroya, Yusa*; Katsumura, Yosuke*; Yoshida, Masaru
Macromolecules, 39(12), p.4132 - 4137, 2006/06
Times Cited Count：5 Percentile：16.83(Polymer Science)Hydrogels, which were synthesized by radiation-induced polymerization and cross-linked reactions of acryloyl-L-proline methyl ester at 0C in aqueous alcohol solutions, exhibit ultraslow volume change in response to variations in external temperature. The shrinking speed of the hydrogels prepared in aqueous alcohol is 1000 times slower than that of the hydrogel prepared in pure water; e.g., the hydrogel prepared in aqueous 1-propanol at 0C shrank in 6 months. It is revealed that the ultraslow thermo-response consists of quick-shrinking and slow-shrinking periods; the ratio between the duration of the two periods depends on the alcohol molecules in the solution. The generation of hydroxyl group at the side chain of the polymer by the coupling reaction between 
-hydroxyalkyl radicals of alcohols and -radical of proline moiety was confirmed by GC/MS analysis of the radiation products. The hydrogen bonding domain containing the hydroxyl groups is proposed to be responsible for the ultraslow response.
-proline methyl ester)--poly(acrylic acid) for selective permeation of metal ionsHasegawa, Shin; Ohashi, Hitoshi; Maekawa, Yasunari; Katakai, Ryoichi*; Yoshida, Masaru
Radiation Physics and Chemistry, 72(5), p.595 - 600, 2005/04
Times Cited Count：16 Percentile：71.86(Chemistry, Physical)Thermo- and pH-responsive gel membranes were synthesized by -ray grafting of pH-responsive poly (acrylic acid) (AAc) onto thermo-responsive polymer gel of acryloyl--proline methyl ester (A-ProOMe). The gel membranes of poly (A-ProOMe) with 15 mol% graft chains of AAc exhibited both thermo- and pH-responses. Under the condition (pH 6.0, 30C) in which the thermo-sensitive unit shrinks and the pH-sensitive unit swells, the selective permeation of Li ion over Co and Ni ions can be achieved.
Chen, J.; Hasegawa, Shin; Ohashi, Hitoshi; Maekawa, Yasunari; Yoshida, Masaru; Katakai, Ryoichi; Tsubokawa, Norio*
Macromolecular Rapid Communications, 23(2), p.141 - 144, 2002/01
Times Cited Count：9 Percentile：33.27(Polymer Science)no abstracts in English
Hiroki, Akihiro*; Maekawa, Yasunari; Yoshida, Masaru; Katakai, Ryoichi*
Polymer, 42(15), p.6403 - 6408, 2001/07
Times Cited Count：9 Percentile：38.25(Polymer Science)no abstracts in English
Hendri, J.*; Hiroki, Akihiro*; Maekawa, Yasunari; Yoshida, Masaru; Katakai, Ryoichi*
Radiation Physics and Chemistry, 61(2), p.155 - 161, 2001/05
Times Cited Count：2 Percentile：19.66(Chemistry, Physical)no abstracts in English
Hendri, J.*; Hiroki, Akihiro*; Maekawa, Yasunari; Yoshida, Masaru; Katakai, Ryoichi*
Radiation Physics and Chemistry, 60(6), p.617 - 624, 2001/03
Times Cited Count：33 Percentile：89.5(Chemistry, Physical)no abstracts in English
Hiroki, Akihiro*; Maekawa, Yasunari; Yoshida, Masaru; Kubota, Kenji*; Katakai, Ryoichi*
Polymer, 42(5), p.1863 - 1867, 2000/12
Times Cited Count：41 Percentile：79.55(Polymer Science)no abstracts in English
-irradiationYoshida, Masaru; Hendri, J.*; Maekawa, Yasunari; Kume, Tamikazu; Katakai, Ryoichi*; Said, A. E. A.; Hegazy, E. A.
Chitin and Chitosan; Chitin and Chitosan in Life Science, p.43 - 46, 2000/00
no abstracts in English
Hiroki, Akihiro*; *; Yoshida, Masaru; Suwa, Takeshi; Asano, Masaharu; Katakai, Ryoichi*
Designed Monomers and Polymers, 3(3), p.381 - 387, 2000/00
Times Cited Count：3 Percentile：15.53(Polymer Science)no abstracts in English
-point temperatureHiroki, Akihiro*; Yoshida, Masaru; *; Asano, Masaharu; N.Reber*; R.Spohr*; Kubota, Hitoshi*; Katakai, Ryoichi*
Radiat. Eff. Defects Solids, 147, p.165 - 175, 1999/00
no abstracts in English
Yoshida, Masaru; Asano, Masaharu; Suwa, Takeshi; Katakai, Ryoichi*
Radiation Physics and Chemistry, 55(5-6), p.677 - 680, 1999/00
Times Cited Count：24 Percentile：84.01(Chemistry, Physical)no abstracts in English
Hiroki, Akihiro*; Yoshida, Masaru; *; Asano, Masaharu; N.Reber*; R.Spohr*; Kumakura, Minoru*; Katakai, Ryoichi*
J. Polym. Sci., Part A, 36(10), p.1495 - 1500, 1998/00
no abstracts in English
Yoshida, Masaru; Asano, Masaharu; Suwa, Takeshi; N.Reber*; R.Spohr*; Katakai, Ryoichi*
Advanced Materials, (9), p.757 - 758, 1997/09
Times Cited Count：28 Percentile：98.06(Chemistry, Multidisciplinary)no abstracts in English
Yoshida, Masaru; Asano, Masaharu; Omichi, Hideki; Kamimura, Wataru*; Kumakura, Minoru*; Katakai, Ryoichi*
Macromolecules, 30(9), p.2795 - 2796, 1997/05
Times Cited Count：16 Percentile：58.03(Polymer Science)no abstracts in English
Yoshida, Masaru; *; Asano, Masaharu; Suwa, Takeshi; Kubota, Hitoshi*; Katakai, Ryoichi*
J. Polym. Sci., Part A, 35, p.3075 - 3077, 1997/00
no abstracts in English
