研究者詳細 - 大久保　貴広

FT-IR and NMR Study on Concentration-Dependent Vesicle-Micelle Transition in CTAB/SOS/D2O Ternary System 査読

H. Nakanishi, K. Tsuchiya, T. Ohkubo, H. Sakai, M. Abe

材料技術 24 ( 1 ) 20 - 26 2006年

Pore-size control of carbon nanospace with ultrasonic irradiation

T. Ohkubo, R. Hori, K. Tsuchiya, H. Sakai, M. Abe

2006 NSTI Nanotechnology Conference and Trade Show - NSTI Nanotech 2006 Technical Proceedings 1 162 - 165 2006年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In this study, we examined the micropore-size control on activated carbons by ultrasonic irradiation with various conditions. Pitch-based activated carbon fiber (ACF) was used for the sample having relatively uniform micropores whose micropore size was determined as 1.15 nm from the measurement of nitrogen adsorption isotherm at 77 K and high-resolution αs-plot analysis. Also, the ultrasonic irradiations to ACF were carried out in the water bath with various irradiation times and at three irradiation frequencies (40 kHz, 200 kHz, and 1 MHz). The results indicate that we can decrease the pore volume and average pore widths of ACFs with longer irradiation time. Also, we examined the dependence of ultrasonic frequencies on micropore-size control. The average pore width of ACF irradiated by 40 kHz was decreased over 10% from the original one. This result suggests that the nanospaces of ACF are collapsed as a result of sonication. Besides, larger pores, are more easily collapsed selectively.

Preparation of mesoporous titania particles with photocatalytic activity under visible-light irradiation 査読

H Shibata, T Mukai, T Akita, T Ohkubo, H Sakai, M Abe

CHEMISTRY LETTERS 34 ( 12 ) 1696 - 1697 2005年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CHEMICAL SOC JAPAN

Novel visible light-responsive photocatalytic mesoporous titania particles were prepared using the sol-gel reaction of titanium oxysulfate sulfuric acid hydrate TiOSO(4)(.)xH(2)SO(4)(.) xH(2)O in aqueous solution in the presence of lyotropic cetyltrimethylammonium bromide (CTAB) liquid crystal as template. The absorption threshold of the calcined particles shifted toward the longer wavelength side and they showed a photocatalytic activity in the oxidation of gaseous 2-propanol under visible light (> 440 nm) irradiation.

DOI： 10.1246/cl.2005.1696

Direct synthesis of mesoporous titania particles having a crystalline wall 査読

その他リンク： http://orcid.org/0000-0001-5907-3683

H Shibata, T Ogura, T Mukai, T Ohkubo, H Sakai, M Abe

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 127 ( 47 ) 16396 - 16397 2005年11月

Photoinduced reversible change of fluid viscosity 査読

H Sakai, Y Orihara, H Kodashima, A Matsumura, T Ohkubo, K Tsuchiya, M Abe

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 127 ( 39 ) 13454 - 13455 2005年10月

Membrane properties of cationic liposomes composed of dipalmitoylphosphatidylcholine and dipalmityldimethylammonium bromide 査読

S Yokoyama, A Inagaki, T Imura, T Ohkubo, N Tsubaki, H Sakai, M Abe

COLLOIDS AND SURFACES B-BIOINTERFACES 44 ( 4 ) 204 - 210 2005年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Cationic liposomes composed of dipalmitoylphosphatidylcholine (DPPC) and dipalmityldimethylammmonium bromide (DPAB) were prepared by the Bangham method and the effect of DPAB on the membrane properties was examined in terms of liposomal shape, particle size, trapping efficiency, surface potential and dispersibility. The dispersibility of the mixed DPPC/DPAB liposomes (the mole fraction of DPAB (X-DPAB) >= 0.05) was excellent and the dispersibility was maintained for 6 months, since the zeta-potential of the mixed liposomes was approximately +40 mV. The trapping efficiency of the mixed DPPC/DPAB liposomes (X-DPAB = 0.05) was 10 times greater than that of the DPPC liposomes, and the value was largest among the mixed liposomes (X-DPAB = 0-1.0). Freeze-fracture electron micrographs indicated that the shape of the mixed DPPC/DPAB liposomes (XDPAB = 0.05) was that of large unilamellar vesicles (LUVs) with a diameter of approximately 2 mu m, while the shape of the DPPC liposomes was that of multilamellar vesicles (MLVs). The mixed liposomes had, therefore, a high trapping efficiency. Furthermore, the shape of the mixed DPPC/DPAB liposomes (X-DPAB = 0.75) was also that of LUVs with a diameter of approximately mu m and these had a high trapping efficiency. Whereas, the particle size (500 nm) of the mixed DPPC/DPAB liposomes (X-DPAB = 0.25) was smaller than that of the former and had the minimum trapping efficiency. The phase transition temperature of the liposomal bilayer membranes indicated a maximum value at 0.25-0.30 mole fractions of DPAB. These facts were considered to be due to the fact that DPPC and DPAB, whose molar ratio was 7.5:2.5, were tightly packed in the liposomal bilayer membranes and that the curvature of the liposomal particle was resultantly large. Nevertheless, LUVs having a high trapping efficiency were easily obtained by mixing a small amount of DPAB with the DPPC. (c) 2005 Published by Elsevier B.V.

DOI： 10.1016/j.colsurfb.2005.01.005

Preparation of ZrB 2 and HfB 2 by metallothermic reduction of ZrO 2, ZrSiO 4, and HfO 2 査読

その他リンク： http://orcid.org/0000-0001-5907-3683

Takahiro Ohkubo, Tetsuo Ono, Katsuhiro Nishiyama, Susumu Niwa, Hideki Sakai, Masumi Koishi, Masahiko Abe

Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 52 ( 9 ) 664 - 669 2005年9月

担当区分：筆頭著者記述言語：日本語掲載種別：研究論文（学術雑誌）

ZrB 2 and HfB 2 were prepared by metallothermic reduction (MTR) of ZrO 2, ZrSiO 4, and HfO 2 with Mg or Mg and MgO mixtures. We understood that the theory of function-building fine particle preparation was able to be applied to synthesize nano-atomized fine particles of ZrB 2. ZrB 2 can also be obtained directly from mixture of ZrSiO 4, B 2O 3, and Mg by MTR method. This sample has no borides such as silicon boride except for ZrB 2. Therefore, this result shows the possibility to obtain ZrB 2 easily from natural source. In addition, HfB 2 can also be synthesized by MTR method using HfO 2 which was calcined over 750°C.

DOI： 10.2497/jjspm.52.664

Bドープによる可視光応答型TiO2の調製とその光物性査読

その他リンク： http://orcid.org/0000-0001-5907-3683

大久保貴広, 秋田隆仁, 柴田裕史, 丹羽進, 西山勝廣, 酒井秀樹, 阿部正彦

粉体および粉末冶金 52 ( 7 ) 495 - 499 2005年7月

金属熱還元法を用いた窒素ドープ型酸化チタンの調製とその光物性査読

大久保貴広, 秋田隆仁, 柴田裕史, 丹羽進, 西山勝廣, 酒井秀樹, 阿部正彦

粉体および粉末冶金 52 ( 7 ) 489 - 494 2005年7月

Synthesis of Microtubes with a Surface of “House of Cards” Structure via Needlelike Particles and Control of Their Pore Size 査読

K. Mitsuhashi, N. Tagami, K. Tanabe, T. Ohkubo, H. Sakai, M. Koishi, M. Abe

Langmuir 21 ( 8 ) 3659 - 3663 2005年4月

Novel approach for the preparation of metal containing mesoporous silica using solubilization of fatty acid salt 査読

A Yamaguchi, M Yokoyama, T Ogura, K Oyaizu, M Yuasa, T Ohkubo, H Sakai, M Abe

CHEMISTRY LETTERS 34 ( 3 ) 346 - 347 2005年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CHEMICAL SOC JAPAN

We have prepared copper-containing mesoporous silica (Cu/MS) using solubilization of copper oleate in nonionic surfactant aggregates. The amount of copper loading in calcined Cu/MS corresponded to the amount of copper oleate solubilized in surfactant aggregates of the mixed solution.

DOI： 10.1246/cl.2005.346

Nanospace molecular science and adsorption 査読

K Kaneko, T Ohba, T Ohkubo, S Utsumi, H Kanoh, M Yudasaka, S Iijima

ADSORPTION-JOURNAL OF THE INTERNATIONAL ADSORPTION SOCIETY 11 21 - 28 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

The relationships between the enhanced interaction potential and intensive confinement effect of slit-shaped and cylindrical nanospaces are shown. The structures of water molecules and aqueous ions confined in nanospaces of activated carbon fiber (ACF) and single wall carbon nanohorn (SWNH)s were studied by adsorption, in situ small angle X-ray scattering(SAXS), GCMC simulation, and EXAFS spectroscopy. Water molecules are associated with each other to form the clusters, being stabilized in the carbon nanospaces. This stabilization mechanism of water in carbon nanospaces were evidenced by the interaction potential calculation, GCMC simulation, and the density fluctuation analysis of in situ SAXS. The Ornstein-Zernike analysis of in situ SAXS profiles lead to the conclusion that the critical size of water clusters for predominant water adsorption in hydrophobic carbon nanospaces is about 0.5 nm corresponding to the octomer to decamer. The adsorption hysteresis of water adsorption isotherm of nanoporous carbon was interpreted by the cluster growth, which is confirmed by the density fluctuation analysis. The Rb and Br ions confined in the carbon nanospaces were examined by EXAFS spectroscopy. The remarkable decreases in the hydration number and the water-Rb ion distance of the solution confined in the nanospaces were observed. In particular, the hydration number of the Rb ion in the nanospaces of SWNH is less than 3, being much smaller than the hydration number (6) of the bulk solution. The electrical double layer structure in the nanospaces should be quite different from that in the bulk solution.

DOI： 10.1007/s10450-005-5893-8

ミセル電解法による無機薄膜の作成査読

今村仁, 吉岡浩也, 土屋好司, 中野智, 大久保貴広, 岡部慎也, 酒井秀樹, 二瓶好正, 阿部正彦

材料技術 23 27 - 35 2005年

Stearylamine Changes the Liposomal Shape from MLVs to LUVs 査読

Shoko Yokoyama, Akiko Inagaki, Koji Tsuchiya, Hideki Sakai, Tomohiro Imura, Takahiro Ohkubo, Nobuyuki Tsubaki, Masahiko Abe

Journal of Oleo Science 54 ( 4 ) 251 - 254 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）

The shape of mixed dipalmitoylphosphatidylcholine (DPPC)/stearylamine (SA) liposomes prepared by the Bangham method was examined using freeze-fracture electron microscopy. The shape of the mixed DPPC/SA liposomes (XSA = 0.05) was not that of multilamellar vesicles (MLVs) but large unilamellar vesicles (LUVs) with a diameter of approximately 1.0 μm. These facts overthrow the preconceived idea that the shape of the DPPC/SA liposomes prepared by the Bangham method is that of MLVs. The trapping efficiency of the mixed DPPC/SA liposomes (XSA = 0.05) was ten times greater than that of the DPPC liposomes, since the DPPC liposomes were MLVs. The data of the DSC peak for the DPPC/SA liposomes also indicated that the shape of the DPPC/SA liposomes is that of LUVs. We emphasize that the shape of the DPPC liposomes changes from that of MLVs to LUVs by the mixing of a small amount of SA into the DPPC liposomes. © 2005, Japan Oil Chemists' Society. All rights reserved.

DOI： 10.5650/jos.54.251

Mechanism of Concentration-Dependent Vesicle-Micelle Transition in Aqueous Mixture of Cationic and Anionic Surfactants 査読

その他リンク： http://orcid.org/0000-0001-5907-3683

Hisanori Nakanishi, Koji Tsuchiya, Takahiro Ohkubo, Hideki Sakai, Masahiko Abe

Journal of Oleo Science 54 ( 8 ) 443 - 451 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）

The phase behavior of aqueous mixed solution of cationic cetyltrimethyl-ammonium bromide (CTAB) and anionic sodium octylsulfate was studied focusing on the concentration-dependent vesicle-micelle transition. Dynamic light scattering measurements and freeze fracture TEM observations showed that the phase transition occurs in two steps depending on the total surfactant concentration. Equilibrium vesicles (V) formed in dilute solution was shown to transform to micelles (M) through a micelle/ small unilamellar vesicle (M + V) coexisting state. The concentration at which the transition from V to M + V occurs on the SOS-rich side lies around the CMC of pure SOS (120 mM). Moreover, electroconductivity and FT-IR measurements revealed that the phase transition is accompanied by a decrease in the degree of counter ion dissociation from surfactant molecules. Based on these experimental findings, the cause of the phase transition was discussed. © 2005, Japan Oil Chemists' Society. All rights reserved.

DOI： 10.5650/jos.54.443

Phase Behavior of Mixed Solutions of a Cationic Surfactant with a Ferrocenyl Group and an Anionic Surfactant: Surface Chemical and Electrochemical Approaches 査読

その他リンク： http://orcid.org/0000-0001-5907-3683

Effect of Alkyl Chain Length of Phosphatidylcholine on the Membrane Properties of Cationic Liposomes 査読

A. Inagaki, K. Tsuchiya, H. Sakai, T. Imura, T. Ohkubo, N. Tsubaki, S. Yokoyama, M. Abe

材料技術 23 107 - 110 2005年

H. Imamura, K. Tsuchiya, Y. Kondo, N. Yoshino, T. Ohkubo, H. Sakai, M. Abe

J. Oleo Sci. 54 ( 3 ) 125 - 134 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japan Oil Chemists' Society

The phase behavior of mixed solutions of (11-ferrocenyl)undecyltrimethyl-ammonium bromide (FTMA⁺), a redox-active cationic surfactant, and sodium dodecylbenzenesulfonate (SDBS), an anionic surfactant, was investigated in detail, and the mechanisms of spontaneous vesicle formation and the control of reversible formation of vesicles through the redox reaction of FTMA⁺ in the mixed system were also examined. Differential interference optical microscopic observations, particle size measurements, and trapping efficiency measurements revealed that various types of aggregates including mixed micelles, vesicles, and liquid crystals are formed in the system depending on the mixing ratio of FTMA⁺ and SDBS. Ultracentrifugal measurements showed that the composition of bimolecular membranes composed of FTMA⁺ and SDBS differs from the initial surfactant mixing ratio and changes depending on the initial mixing ratio. Surface tension measurements indicated an important contribution of the formation of a pseudo-double chain-type complex through the electrostatic interaction between FTMA⁺ and SDBS to spontaneous vesicle formation. In addition, the existence of a benzyl group in the anionic surfactant was suggested to be important for the pseudo-double chain-type surfactant to take the orientation favorable to vesicle formation.<br>

DOI： 10.5650/jos.54.125

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