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  • 1
    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: We have developed a novel method to construct porous hydroxyapatite (HA) by dual-phase mixing—in other words, generating a porous ceramic body and pore-forming template simultaneously. The technique is based on mixing two immiscible phases: HA slurry and polymethylmethacrylate (PMMA) resin. Naphthalene particles are necessary when greater porosity (〉50%) is wanted. After shaping in a mold, the mixture is subjected to polymerization, drying, pyrolysis, and sintering. The porous HA has been thoroughly characterized with Fourier transformation infrared spectrometry, X-ray diffractometry, environmental scanning electron microscopy coupled with energy-dispersive X-ray analysis, and image analysis. The demanding specifications for bone ingrowth are met: (i) the size of pores and their fenestrations are adjustable, ∼80% within 300–800 μm; (ii) uniform and isotropic porous structure is observed in three directions; (iii) pores are fully interconnected throughout; (iv) the porosity is adjustable up to 60%; and (v) sufficient mechanical strength is present for cell culture and implantation handling. The porous HA can be applied as either implant material or scaffold for bone-tissue engineering.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 8 (1997), S. 543-549 
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Natural self-reinforced composite, bamboo, was surface modified by phosphorylation with urea–H3PO4 and NaOH–H3PO4 methods; then precalcification was performed by immersing samples in saturated Ca(OH)2 solution. After that, calcium phosphate can be formed on the surface of bamboo samples in calcification media: simulated body fluid (1.5 SBF) and accelerated calcification solution (ACS). Experimental results reveal that pre-calcification is an inevitable step for the formation of calcium phosphate. The calcium phosphate formed in 1.5 SBF was identified by thin-film X-ray diffraction as apatite which was not well crystallized. Compared with the urea–H3PO4 method, the NaOH–H3PO4 method has the advantages of quicker and continuous apatite formation and stronger adhesive between apatite and bamboo.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 15 (1996), S. 1882-1885 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 40 (1998), S. 520-529 
    ISSN: 0021-9304
    Keywords: 3D carbon/carbon composite ; collagen/apatite composite ; coating ; grafting ; phosphorylation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A three-dimensional carbon/carbon composite (3D C/C) was studied as potential bone-repairing material; its major mechanical properties were found to be closer to those of human bone than other common bone-repairing materials available. In vitro calcification tests revealed that as-received 3D C/C is almost bioinert in simulated body fluid (SBF) over an immersion period of 4 weeks. To improve the bioactivity of 3D C/C, surface modification was accomplished through two practical routes: (1) grafting with polyethylene glycol (PEG) and (2) phosphorylation and precalcification. After grafting with α, ω di(aminopropyl) polyethylene glycol 800 (NH2-PEG-NH2), a continuous layer of calcium phosphate was formed on the surface of 3D C/C in SBF after 4 weeks. Phosphorylated 3D C/C samples have the ability to induce apatite precipitation after precalcification in a saturated Ca(OH)2 solution for 1 week. To speed up the coating process, a calcification solution with collagen was developed in which a collagen/apatite coating layer can be formed on 3D C/C in 9 h in ambient conditions. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 520-529, 1998.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 40 (1998), S. 490-497 
    ISSN: 0021-9304
    Keywords: hydroxyapatite ; Polyactive™ ; composites ; interface ; mechanical properties ; surface grafting ; coupling agent ; diisocyanate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In an effort to make composites from hydroxyapatite and a PEG/PBT copolymer (Polyactive™ 70/30), chemical linkages were introduced between the filler particles and polymer matrix using hexamethylene diisocyanate as a coupling agent. Infrared spectra (IR) and thermal gravimetric analysis (TGA) confirmed the presence of Polyactive™ 70/30 on the surface of HA filler particles. The amount of chemically bound polymer was 4.7 wt.%, as determined by TGA. The mechanical properties of the composites, that is, tensile strength and Young's modulus, were improved significantly by the introduction of a chemical linkage between the filler particles and polymer matrix compared to control composites. This method provides an effective way to introduce chemical linkage between HA filler particles and a polymer matrix. By optimizing the grafting process, a further improvement of the mechanical properties in the composites can be expected. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 490-497, 1998.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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