Faculty Profiles - HAYAKAWA Satoshi

Molecular dynamic simulation of heterogeneity and chemical states of fluorine in amorphous alkaline earth silicate systems Reviewed

Satoshi Hayakawa, Chikara Ohtsuki, Syuji Matsumoto, Akiyoshi Osaka, Yoshinari Miura

Computational Materials Science 9 ( 3-4 ) 337 - 342 1998.1

Bioactive gel coatings derived from vinyltrimethoxysilane Reviewed

K Tsuru, S Hayakawa, C Ohtsuki, A Osaka

JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY 13 ( 1-3 ) 237 - 240 1998

Language：English Publishing type：Research paper (scientific journal) Publisher：KLUWER ACADEMIC PUBL

An ethanol (EtOH) solution of polymerized vinyltrimethoxysilane (VTMS), about 20-mers, was mixed with an aqueous solution of calcium acetate (Ca(OAc)(2)) and refluxed in N-2 for 1 h to give sols of a typical composition VTMS:H2O:EtOH: Ca(OAc)(2) = 1 :9:8:0.05 (mol). Homogeneous films could be produced, by dip-coating, on Nylon(R) and soda-lime glass, but not on polypropylene or polytetrafluoroethylene. The gel films did not deposit apatite within 14 days of soaking in a simulated body fluid whereas films abraded with emery paper as well as bulk gels deposited apatite on the surfaces within 7 days, indicating the present gel was suitable for bioactive coatings on Nylon(R).

Apatite formation on the surface of silicone elastomer covered with bioactive glass particles Reviewed

Kanji Tsuru, Satoshi Hayakawa, Chikara Ohtsuki, Akiyoshi Osaka

Zairyo/Journal of the Society of Materials Science, Japan 47 ( 6 ) 565 - 570 1998

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Soc Mater Sci, Japan

Surface modification was applied to silicone elastomers via ultrasonic implantation of bioactive 50CaO · 50SiO2 (mol%) glass particles (&lt
45μm in diameter). Silicone elastomers with different hardness, which were sampled from an appropriate stage of their hardening process, were immersed in the bioactive glass-ethanol suspension and subjected to irradiation of ultrasonic energy. The glass particles wholly covered and well adhered to the surface of silicone elastomers when the glass was implanted in the silicone elastomer at the stage of hard gel. Thus the resulting composite formed apatite, which is essential for bone-bonding, in Kokubo solution within 7 days. The cross-sectional analysis of the composite soaked in Kokubo solution indicates that the composite is covered with a complexed layer consisting of the bioactive glass and the in situ formed apatite.

DOI： 10.2472/jsms.47.565

BIOMIMETIC COATING OF BONE-LIKE APATITE ON GLASS BEADS Reviewed

Akiyoshi OSAKA, Shinji TAKEMOTO, Satoshi HAYAKAWA, Chikara OHTSUKI

Journal of the Society of Materials Science, Japan 47 ( 3Appendix ) 60 - 63 1998

Language：English Publishing type：Research paper (scientific journal) Publisher：Society of Materials Science, Japan

Soda lime glass beads were chemically treated by either an aqueous solution of NaOH(3mol/l) or a hydrogen peroxide solution(30vol%)containing TaCl_5 in 5×10^3 mol/l or by both of them. The treated samples ware soaked up to 14 days in a simulated body fluid(SBF):Na^+142.0, K^+5.0, Ca^<2+> 2.5, Mg^<2+>1.5, Cl^-147.8, HCO_3^-4.2, HPO_4^<2->1.0, SO_4^<2->0.5(in 10^<-3>mol/l), or in another solution 1.5 times as concentrated as SBF(1.5SBF). The SBFs were kept at 36.5°C and at 7.25 in pH. Apatite was deposited on the samples treated with the NaOH solution, the H_2O_2/Ta solution, and both of them before soaking in 1.5SBF. Ta(V)ions were present on not only the samples treated with the H_2O_2/Ta solution but those treated with both NaOH and the H_2O_2/Ta solutions. It was concluded that Ta(V)ions on the surface layer had ability of inducing apatite deposition, and the ability was enhanced by the coexitence with silanol groups.

DOI： 10.2472/jsms.47.3appendix_60

Properties of Alumina-Zirconia Powder Prepared from Aluminium Chelate Compound and Zirconium Alkoxide Reviewed

Other Link： https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=243528

KAWABATA Koji, YOSHIMATSU Hideyuki, YABUKI Tatsumi, KUBOTSU Akira, HAYAKAWA Satoshi, OSAKA Akiyoshi, MIURA Yoshinari

Journal of the Ceramic Society of Japan 106 ( 1230 ) 155 - 159 1998

Publisher：The Ceramic Society of Japan

Alumina-zirconia powder (AZ) was prepared by thermal decomposition of organic precursors synthesized from ethyl acetoacetate aluminium diisopropoxide and zirconium tetra-n-butoxide. The specific surface area of AZ was higher than that of alumina-zirconia powder (ALK) prepared from aluminium tri-sec-butoxide and zirconium tetra-n-butoxide in the range of 0-40mol% ZrO₂. The pore radius for AZ containing 0-40mol% ZrO₂ distributed from 1 to 3nm. The true density of AZ was lower than that of ALK in the range of 0-40mol% ZrO₂. Four- and 6-coordinated Al atoms existed in ZrO₂-free AZ, while 5-coordinated Al atoms in addition to 4- and 6-coordinated Al atoms existed in AZ containing 20-80mol% ZrO₂. These results indicate that alumina component and zirconia component in AZ were mixed homogeneously at the atomic level.

DOI： 10.2109/jcersj.106.155

DOI： 10.2472/jsms.56.526_references_DOI_WispPXNoq7EoLH9a3Rg9zT2nh5D

Bioactivity of titanium treated with hydrogen peroxide solutions containing metal chlorides Reviewed

Other Link： http://id.ndl.go.jp/bib/4392630

C Ohtsuki, H Iida, S Hayakawa, A Osaka

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 35 ( 1 ) 39 - 47 1997.4

Language：English Publishing type：Research paper (scientific journal) Publisher：JOHN WILEY & SONS INC

Commercially available pure metallic titanium was chemically treated at 60 degrees C for 24 h with H2O2 solutions containing various metal chlorides to provide titanium with bioactivity, that is, to give it the ability to form a biologically active bone-like apatite layer on the surface. After the chemical treatment the titanium specimens were soaked in a simulated body fluid (the Kokubo solution). Apatite was found to deposit on the specimens treated with the H2O2/TaCl5 and H2O2/SnCl2 solutions. X-ray photoelectron spectroscopic (XPS) study of the specimens treated with those H2O2 solutions indicated that basic Ti-OH groups in titania hydrogel layers on their surfaces were responsible for apatite nucleation and growth. (C) 1997 John Wiley & Sons, Inc.

DOI： 10.1002/(SICI)1097-4636(199704)35:1<39::AID-JBM5>3.0.CO;2-N

MAS-NMR studies of apatite formation on 50CaO・50SiO₂glass in a simulated body fluid(共著) Reviewed

Physics and Chemistry of Glasses 37 ( 5 ) 188 1996.12

³¹P MAS-NMR Studies of Phosphate Salts Formation on Calcium-Containing Oxide Glasses in a Simulated Body Fluid Reviewed

HAYAKAWA Satoshi, TSURU Kanji, IIDA Hirohisa, OHTSUKI Chikara, OSAKA Akiyoshi

Journal of the Ceramic Society of Japan 104 ( 1215 ) 1000 - 1003 1996.11

Authorship：Lead author,　Corresponding author Language：Japanese Publisher：The Ceramic Society of Japan

^<31>P MAS-NMR spectra were measured for pulverized binary and ternary glasses containing Ca^<2+> ions after soaking in a simulated body fluid (Kokubo solution; pH=7.25) for 1 d, and the chemical state of adsorbed phosphate ions were examined. The ^<31>P chemical shift indicated that orthophosphate ions, H_xPO_4^<-(3-x)>(0<x<3), were adsorbed on all the glasses but 60CaO・40Al_2O_3; pyrophosphate ions, H_zP_2O_7^<-(4-z)<(0<z<4), were detected on the aluminate glass, indicating that orthophosphate ions in the Kokubo solution were dimerized on the glass surface. For the glasses such as 60CaO・40Al_2O_3, 40CaO・60B_2O_3, 40aO・30B_2O_3・30Al_2O_3 and 40CaO・30B_2O_3・30SiO_2, those phosphate ions gave broad ^<31>P MAS-NMR spectra, hence have a broad distribution by coordinating to the various surface sites of the glasses. On the other hand, sharp ^<31>P MAS-NMR spectra as for a cortical bone (rabbit) were obtained for the rest of the glasses, 50CaO・50SiO_2 and 40CaO・30B_2O_3・30TiO_2, on which apatite formed in shorter soaking period in the Kokubo solution. It was thus concluded that presence of orthophosphate ions on the glass surfaces favored the deposition of apatite.

DOI： 10.2109/jcersj.104.1000

Other Link： https://jlc.jst.go.jp/DN/JALC/00370917762?from=CiNii

P-31 MAS-NMR studies of phosphate salts formation on calcium-containing oxide glasses in a simulated body fluid Reviewed

S Hayakawa, K Tsuru, H Iida, C Ohtsuki, A Osaka

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 104 ( 11 ) 1000 - 1003 1996.11

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

P-31 MAS-NMR spectra were measured for pulverized binary and ternary glasses containing Ca2+ ions after soaking in a simulated body fluid (Kokubo solution; pH=7.25) for 1 d, and the chemical state of adsorbed phosphate ions were examined. The P-31 chemical shift indicated that orthophosphate ions, H2PO4-(3-x) (0<x<3), were adsorbed on all the glasses but 60CaO . 40Al(2)O(3); pyrophosphate ions, H2P2O7-(4-x) (0<z<4), were detected on the aluminate glass, indicating that orthophosphate ions in the Kokubo solution were dimerized on the glass surface. For the glasses such as 60CaO . 40Al(2)O(3), 40CaO . 60B(2)O(3), 40CaO . 30B(2)O(3) . 30Al(2)O(3) and 40CaO . 30B(2)O(3) . 30SiO(2), those phosphate ions gave broad P-31 MAS-NMR spectra, hence have a broad distribution by coordinating to the various surface sites of the glasses. On the other hand, sharp P-31 MAS-NMR spectra as for a cortical bone (rabbit) were obtained for the rest of the glasses, (CaO)-Ca-50 . 50SiO(2) and 40CaO . 30B(2)O(3) . 30TiO(2), on which apatite formed in shorter soaking period in the Kokubo solution. It was thus concluded that presence of orthophosphate ions on the glass surfaces favored the deposition of apatite.

DOI： 10.2109/jcersj.104.1000

IR AND NMR STRUCTURAL STUDIES ON LEAD VANADATE GLASSES Reviewed

S HAYAKAWA, T YOKO, S SAKKA

JOURNAL OF NON-CRYSTALLINE SOLIDS 183 ( 1-2 ) 73 - 84 1995.4

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The structure of lead vanadate glasses, xPbO . (100 - x)V2O5, (x = 55, 50, 40, 30) has been investigated by means of infrared and V-51 static and magic angle spinning nuclear magnetic resonance (MAS-NMR) and Pb-207 MAS-NMR spectroscopies. The V-51 NMR spectral parameters of various constituent vanadate groups in lead vanadate glasses were determined by spectrum simulation on the basis of our previous results on alkaline earth vanadate glasses. The structure of 55PbO . 45V(2)O(5) glass mainly consists of VO4 tetrahedra, which are composed of V2O74- and (VO3)(n) single chains. The structure of xPbO . (100 - x)V2O5 glasses (x = 30, 40, 50) consists of both VO4 tetrahedra and VO5 trigonal bipyramids. These VOn polyhedra (n = 4, 5) compose at least four types of vanadate group, i.e., V2O74-, (VO3)(n) single chains, branched VO4 group and (V2O8)(n) zigzag chains depending on the PbO content.

DOI： 10.1016/0022-3093(94)00652-0

Structural studies on alkaline earth vanadate glasses (part 1) - IR spectroscopic study - Reviewed

Satoshi Hayakawa, Toshinobu Yoko, Sumio Sakka

Journal of the Ceramic Society of Japan. International ed. 102 ( 6 ) 522 - 528 1994.6

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Fuji Marketing Research Co Ltd

The structure of alkaline earth vanadate glasses of the compositions, xMO·(100-x)V2O5 (M = Mg, Ca, Sr, Ba, x = 30, 40, 45, 50, 55), has been investigated by means of IR spectroscopy with reference to various crystalline alkaline earth vanadates structurally known. It is found that the structure of alkaline earth vanadate glasses is very similar to each other and mainly consists of VO4-tetrahedra which form either (VO3)n-single chains as found in Sr(VO3)2 and Ba(VO3)2 crystals or the three dimensional arrangement of the corner-sharing branched VO4-tetrahedral groups as found in molten and amorphous V2O5. It is stressed that the glass network of the V2O5-rich glasses, 30MO·70V2O5, also mainly consists of VO4-tetrahedra.

Structural studies on alkaline earth vanadate glasses (part 2) - 51V NMR spectroscopic study - Reviewed

Satoshi Hayakawa, Toshinobu Yoko, Sumio Sakka

Journal of the Ceramic Society of Japan. International ed. 102 ( 6 ) 529 - 535 1994.6

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Fuji Marketing Research Co Ltd

The structure of alkaline earth vanadate glasses, xMO · (100-x)V2O5 (M = Ca, Sr, Ba, x = 30, 40, 45, 50, 55), has been investigated by means of 51V static and magic angle spinning (MAS) NMR spectroscopies. The 51V NMR spectral parameters of various constituent vanadate groups contained in the vanadate glasses were determined by the spectrum simulation with reference to those of various crystalline vanadates obtained previously. It was found that the structure of alkaline earth vanadate glasses consists mainly of VO4-tetrahedra in accordance with authors' previous results based on the IR study. It was deduced that for x = 50 the glass network is mainly constituted of one dimensional (VO3)n-single chains, and for x ≤ 45 the decrease of the MO content yields a mixture of the V2O5-rich phase constituted of three dimensionally branched VO4-groups and the MO-rich phase constituted of the VO5-trigonal bipyramids, followed by the decrease of (VO3)n-single chains.

51V NMR studies of crystalline monovalent and divalent metal metavanadates Reviewed

Satoshi Hayakawa, Toshinobu Yoko, Sumio Sakka

Journal of Solid State Chemistry 112 ( 2 ) 329 - 339 1994

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

51V static and magic-angle spinning (MAS) NMR spectra of crystalline monovalent metal metavanadates LiVO3, α- and βNaVO3, KVO3, CsVO3, β-AgVO3, and NH4VO3 and divalent metal metavanadates M(VO3)2 (M = Mg, Ca, Sr, Ba, Zn, Pb) have been measured in order to establish the relationships between the various NMR parameters, such as isotropic chemical shift, δiso, chemical shift anisotropy, |Δ
δ|, the asymmetry parameter, η, and the crystallographic parameters. When the structural units are the same, in this case VO4 tetrahedra or VO5 trigonal bipyramids, the δiso decrease almost linearly with decreasing average V-O bond length, independent of the polymerization degree and linkage mode of the VOn polyhedra. |Δ
δ|, increases with the polymerization degree and the degree of the structural distortion of the VOn polyhedron. It is found possible to predict the structural unit and the polymerization degree on the basis of the relation between |Δ
δ| and η. © 1994 Academic Press, Inc.

DOI： 10.1006/jssc.1994.1313

Structural Studies on Alkaline Earth Vanadate Glasses (Part 1) Reviewed

Satoshi HAYAKAWA, Toshinobu YOKO, Sumio SAKKA

Journal of the Ceramic Society of Japan 102 ( 1186 ) 522 - 529 1994

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Ceramic Society of Japan

The structure of alkaline earth vanadate glasses of the compositions, _xMO・(100-x)V_2O_5 (M=Mg, Ca, Sr, Ba, x=30, 40, 45, 50, 55) , has been investigated by me ans of IR spectroscopy with reference to various crys talline alkaline earth vanadates structurally known. It is found that the structure of alkaline earth vanadate glasses is very similar to each other and mainly con sists of V0_4 tetrahedra which form either (VO_3) single chains as found in Sr (VO_3)_2 and Ba (VO_3)_2 crystals or the three dimensional arrangement of the corner sharing branched VO_4 tetrahedral groups as found in molten and amorphous V_2O_5. It is stressed that the glass network of the V_2O_5-rich glasses, 30MO・70V_2O_5, also mainly consists of VO_4 tetrahedra.

DOI： 10.2109/jcersj.102.522

⁵¹V NMR Studies of Crystalline Divalent Metal Vanadates and Divanadates Reviewed

Satoshi Hayakawa, Toshinobu Yoko, Sumio Sakka

Bulletin of the Chemical Society of Japan 66 ( 11 ) 3393 - 3400 1993.11

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：The Chemical Society of Japan

⁵¹V static and magic-angle spinning (MAS) NMR spectra of crystalline divalent metal vanadates, M₃(VO₄)₂ (M = Mg, Sr, Ba, Zn, Pb) and Mg₂M′(VO₄)₂ (M′ = Sr, Ba, Pb) and divanadates, M₂V₂O₇ (M = Mg, Ca, Sr, Ba, Zn, Pb) have been measured. In vanadates and dichromate-type divanadates, the ⁵¹V isotropic chemical shifts decrease linearly with decreasing electronegativity of divalent metal atom adjacent to the VO₄-tetrahedron. This was interpreted by considering that the electron density and the symmetry of VO₄-tetrahedron increases with decreasing electronegativity of divalent metal atom. This effect was more significant in vanadates than in divanadates. In divanadates the isotropic chemical shifts of the thortveitite-type configuration appeared at lower frequencies than that of the dichromate-type configuration. This was explained by assuming that the degree of s-hybridization of the oxygen orbitals in the V–O–V bonds is higher in the thortveitite-type than in the dichromate-type.

DOI： 10.1246/bcsj.66.3393