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  • 1
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It has been shown that polydimethylsiloxane (PDMS)–CaO–SiO2–TiO2 and poly(tetramethylene oxide) (PTMO)–CaO–TiO2 hybrids form apatite on their surfaces in a simulated body fluid (SBF) and show mechanical properties similar to those of human cancellous bones. In the present study, changes, caused by soaking in SBF, were measured in the mechanical properties of PDMS–CaO–SiO2–TiO2 hybrids with different CaO and TiO2 contents and PTMO–CaO–TiO2 hybrids with different CaO contents. Significant decreases in the strength and strain at failure of the hybrids were observed for the PDMS–CaO–SiO2–TiO2 hybrids with high CaO or TiO2 contents and PTMO–CaO–TiO2 hybrids with a high CaO content after soaking in SBF for 4 w. This indicates that incorporation of a large amount of CaO component into the hybrids should result in the deterioration of the hybrids in the body environment.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 86 (2003), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Hydrolysis and polycondensation of poly(dimethylsiloxane) (PDMS), tetraethoxysilane (TEOS), and calcium nitrate, added with tetraisopropyltitanate (TiPT) at a TiPT/(TiPT + TEOS) molar ratio of 0.15, gave a pore- and crack-free transparent monolithic organic-inorganic hybrid material. It was speculated to be composed of a Si–O–Ti–O− network modified with methyl groups, and a Ca2+ ion ionically bonded to the network. The hybrid obtained showed a high apatite-forming ability on its surface in a simulated body fluid that is indicative of high bioactivity, as well as mechanical properties such as bending strength, Young's modulus, and strain at failure, analogous to those of the human cancellous bone. This hybrid material is expected to be useful as a new type of bioactive bone-repairing material.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 84 (2001), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Formation of bonelike apatite on zirconia gel in a simulated body fluid (SBF) with ion concentrations almost equal to those in human blood plasma, in modified SBF solutions to have increased pH values, and modified SBF solutions to have increased concentrations of calcium and phosphate ions has been investigated. The zirconia gel forms apatite on its surface in SBF, indicating that Zr-OH groups, abundant on the gel, act as effective apatite nucleation centers. Apatite formation is accelerated by increases in pH and in the concentration of calcium and phosphate ions, which is explained by an increase in the ionic activity product of the apatite in the SBF. These results suggest that zirconia ceramics may exhibit a bone-bonding ability by forming an apatite layer on their surfaces in the living body when they are modified to have many Zr-OH groups on their surfaces.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A chemically durable glass that contains a large amount of phosphorus is useful for in situ irradiation of cancers. It can be activated to be a β-emitter with a half-life of 14·3 d by using neutron bombardment. Microspheres of the activated glass that are injected to tumors can irradiate the tumors directly with β-rays without irradiating neighboring normal tissues. In the present study, P+ ions in various doses have been implanted into a pure silica glass in a plate form at 200 keV. Almost all the implanted phosphorus is present in the inner region of the glass rather than in the surface region, taking the form of phosphorus colloids for all the doses in the range of 5 × 1016-1 × 1018 cm-2. A large number of amorphous phosphorus colloid particles with diameters of 10-150 nm are formed in the silica glass that has been implanted with a dose of 1 × 1018 cm-2; these colloid particles are distributed widely in a layer that is centered at a depth of 200-250 nm. All the investigated glasses hardly release any phosphorus and silicon into water at a temperature of 95°C, even after 7 d. A silica glass that has been implanted with P+ ions at 200 keV with a dose of 1 × 1018 cm-2 is believed to be useful as a radiotherapy glass with sufficient phosphorus content and high chemical durability.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The process of apatite formation on the surface of Na2O–SiO2 glass in a body environment was investigated, mainly by X-ray photoelectron spectroscopy, as a function of soaking time in a simulated body fluid (SBF). The glass was found to release Na+ ions via exchange with H3O+ ions in the SBF to form Si—OH groups on its surface. These Si—OH groups induced apatite formation indirectly, by forming calcium silicate and amorphous calcium phosphate. The formation of the calcium silicate and amorphous calcium phosphate is attributed to electrostatic interactions between the Si—OH groups on the glass surface and the calcium and phosphate ions in the SBF.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 84 (2001), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An essential condition for an artificial material to bond to living bone is the formation of bonelike apatite on its surface in the living body. The bonelike apatite can be reproduced on the bone-bonding material even in an acellular simulated body fluid (SBF) with ion concentrations almost equal to those of human blood plasma. In the present study, the dependence of the apatite-forming abilities of sodium-containing titania gels in a SBF on composition and structure is examined. The sodium-containing titania gels are model substances produced on the surface layer of bioactive titanium metal prepared by sodium hydroxide solution and heat treatments. When sodium-containing titania gels are immersed in the SBF, Na+ ions incorporated in the gels are exchanged with the H3O+ ions in the SBF. This ion exchange causes an accompanying increase in the pH of the SBF and increases its ionic activity product, thus providing favorable conditions for apatite nucleation on the surfaces of the gels. Nevertheless, sodium-containing titania gels that do not contain anatase do not form apatite on their surfaces. Independent of the composition, the gels form apatite on their surfaces in the SBF, specifically when they contain anatase. These results imply that the Ti-OH groups on titania, which have been proposed to be responsible for the apatite formation, are effective for apatite nucleation when they are arranged in a specific structural unit based on the anatase structure.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 293 (Aug. 1998), p. 65-82 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 284-286 (Apr. 2005), p. 381-386 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this study, we examined in vivo performance of newly developed hydroxyapatite (HA)ceramics, which is obtained by sintering the HA powder mixed with CaO·MgO·SiO2-based glass at 1000°C (liquid phase sintering). Bioactivity of this glass-containing HA was evaluated compared with the control HA by mechanical test and histological examination. The glass-containing HA showed higher bone-bonding strength than the control HA throughout the experimental period. Lightmicroscope and backscattered scanning electron microscope (SEM) showed that the both kinds of implants bonded directly to the bone. High bioactivity in vivo, especially in the early period after implantation, of this newly developed HA was confirmed, which is one of the essential requirement for optimal bone substitutes
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 284-286 (Apr. 2005), p. 775-778 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Ethylene-vinyl alcohol copolymer (EVOH), poly(ethylene terephthalate) (PET) and polyethylene (PE) were modified with calcium silicate on their surfaces by a sol-gel method, before or after glow discharge treatment in O2 gas, soaked in a simulated body fluid (SBF) and implanted into knee bone of a rabbit. EVOH and PET formed nano-sized bonelike apatite uniformly on theirsurfaces in SBF, without being subjected to the glow discharge, and bonded to the living bone of the rabbit, whereas PE formed the apatite only sparsely even when being subjected to the glow discharge. Three dimensional fabrics with open spaces in various sizes of the former fibers modified with the calcium silicate might be useful as bone substitutes
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 284-286 (Apr. 2005), p. 97-100 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Two types of new bioactive polymethylmethacrylate (PMMA)-based bone cements containing nano−sized titania (TiO2) particles were prepared and evaluated to assess the effect of TiO2 content on their mechanical properties and osteoconductivity. We prepared two types of bioactive bone cement, ST50c and ST60c, which contained 50 wt% silanized TiO2 and 60 wt% silanized TiO2, respectively. Commercially available PMMA cement (PMMAc) was used as acontrol. The cements were inserted into rat tibiae and solidified in situ. After 6 and 12 weeks, they were taken out for evaluation of osteoconductivity by scanning electron microscopy (SEM), contact microradiography (CMR) and Giemsa surface staining. SEM revealed that ST60c and ST50c apposed to bone directly while PMMAc did not. The affinity index of ST60c was significantly higher than forthe other cements at each time interval. The results showed that ST60c was a promising material, but its mechanical strength should be improved before application in prosthesis fixation
    Type of Medium: Electronic Resource
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