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  • 1
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In the preparation of fibrous hydroxyapatite (HAp), using the gel system consisting of agar gel containing calcium nitrate and over-layered (NH4)2HPO4 solution, the pH of the solution was found to greatly influence the growth rate and morphology of the resultant products. In particular, a pH value of about 9–10 produced straight fibrous HAp in the shortest time. Also, the Ca/P molar ratio of the product increased with the pH value of the starting solution. The growth rate and morphology of the product were correlated to the ion species present in the solution at different pHs.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A dense, uniform and highly biologically active bone-like apatite layer can be formed in arbitrary thickness on any kind and shape of solid substrate surface by the following biomimetic method at ordinary temperature and pressure. First, a substrate is set in contact with particles of bioactive CaO SiO2 based glass soaked in a simulated body fluid (SBF) with inorganic ion concentrations nearly equal to those of human blood plasma. Second, the substrate is soaked in another solution with ion concentrations 1.5 times those of SBF (1.5 SBF). In the present study, organic polymer substrates treated with 5 M NaOH solution were subjected to the above mentioned biomimetic process. The induction periods for the apatite nucleation on polyethyl-eneterephthalate (PET), polymethylmethacrylate (PMMA), polyamide 6 (PA6), and polyethersulfone (PESF) substrates were reduced from 24 to 12 h with the NaOH treatment. The adhesive strength of the formed apatite layer were increased from 3.5 to 8.6 MPa, from 1.1 to 3.4 MPa, and from 0.6 to 5.3 MPa with the NaOH treatment, for PET, PMMA, and PA 6, respectively. It was assumed that highly polar groups, such as carboxyl and sulfinyl ones formed by the hydrolysis of an ester group on PET and PMMA and of an amide group on PA 6, or of a sulfonyl group on PESF with the NaOH treatment, attached a large number of hydrated silica dissolved from the glass particles, to accelerate the apatite nucleation, and also to form a strong bond with the apatite. The apatite-organic polymer composites thus obtained are expected to be useful as bone-repairing as well as soft tissue-repairing materials. © 1994 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A 20-μm thick apatite layer was coated onto polyethersulfone (PES) rectangular plates by soaking them in simulated body fluid containing CaO-SiO2 based glass powder. Coated and uncoated PES plates (10 × 15 × 1.5 mm) were implanted in the tibiae of rabbits, which were sacrificed 8, 16, and 30 weeks thereafter, and the samples were examined histologically using contact microradiography (CMR), Giemsa surface staining, and a scanning electron microscope connected to an electron probe microanalyzer (SEM-EPMA). The tensile failure loads at the bone/implant interfaces were determined using the detaching test. The histological examinations showed excellent bone apposition on coated PES and the sign of degradation of the apatite layer at remodeling lacunae. The apatite layer underwent complete resorption and was replaced by bone in most areas of the bone/implant interface after 30 weeks. Bone did not bond directly to uncoated PES after each follow-up period. The failure loads between bone and coated PES at 8, 16, and 30 weeks after implantation were 1.17 ± 0.35, 2.36 ± 0.53, and 1.45 ± 0.48 kg, respectively. Those between bone and uncoated PES were nearly 0 kg at each postimplantation period. Failure during the detaching test occurred at the bone/apatite interface or near it after 8 weeks. After 16 weeks, it usually occurred at the apatite/PES interface or near it, and occasionally in the middle of the apatite layer. The apatite layer was hardly detected at the failured interface after 30 weeks. In this study, an apatite-coated PES produced using a biomimetic method was demonstrated to bond directly to bone without any intervening soft tissue, which indicates that this material possesses excellent bioactivity. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 34 (1997), S. 305-315 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Self-assembled monolayers (SAMs) of alkanethiols having CH3, PO4H2, COOH, CONH2, OH, and NH2 terminal groups formed on a gold surface via sulfur attachment were soaked in a simulated body fluid (SBF), whose ion concentrations were nearly equal to those of human blood plasma, at 37°C for up to 40 days. The effect of their terminal functional groups on apatite formation was assessed using X-ray photo-electron spectroscopic (XPS) measurement and a quartz crystal microbalance (QCM) technique. The Ca and P atoms were detected, of which element intensities increased with time, on SAMs except for the alkanethiol having the methyl terminal group. The Ca/P atomic ratios of the apatites formed on the SAMs ranged from around 1.0 to around 1.3. The most potent inducer for apatite formation, judged from the growth rate (micrometers per day) calculated from the weight change during QCM measurement, was the SAM of the alkanethiol with the PO4H2 group, followed by that of the alkanethiol with the COOH group. The SAMs of the alkanethiols with the CONH2, OH, and NH2 groups possessed much weaker inducing powers than the former two SAMs. Little weight change was observed for the methyl-group-terminated alkanethiol SAM. The growth rates increased with time, irrespective of the terminal group species among apatite formation-inducing groups. During the experimental observation period, the following relationship held. The growth rate decreased in the order PO4H2 〉 COOH ≫ CONH2 ≃ OH 〉 NH2 ≫ CH3 ≃ 0. Since negatively charged groups strongly induced apatite formation but the positively charged group did not, it can be said that the apatite formation initiated via calcium ion-adsorption upon complexation with a negative surface-charged group may be dominant in biomaterial calcification where ionic species directly contact the biomaterial surface in body fluids. © 1997 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 5
    Publication Date: 1994-11-01
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Wiley on behalf of American Ceramic Society.
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  • 6
    Publication Date: 1996-09-01
    Print ISSN: 0142-9612
    Electronic ISSN: 1878-5905
    Topics: Biology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Medicine
    Published by Elsevier
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