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  • Articles  (2,275)
  • Engineering  (1,639)
  • Polymer and Materials Science  (636)
  • 1985-1989  (2,275)
  • Technology  (2,275)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. iii 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 241-250 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This is a review of the surface chemistry of bone mineral and its synthetic counterpart hydroxypapatite. Small-angle x-ray scattering and low-temperature nitrogen adsorption measurements show bone mineral surfaces range from 100 to 200 m2/g. The heats of adsorption of small molecules on bone and apatite surfaces show that these materials have polarizing surfaces which form strong bonds with polar and polarizable molecules. Water is hydrogen bonded to these surfaces with energies ranging from 23 Kcal/mol, for low coverage, to 11 Kcal/mol after two full layers; the latter value shows that after two monolayers the water is bonded as strongly to the solution as it is to the apatite surface. Stearic acid in cyclohexane adsorbs on bone and apatite surfaces in a closed-packed manner with the straight-chain molecules in parallel array with the end carboxyl groups hydrogen bonded to surface electronegative ions. Synthetic hydroxyapatite has long been used in chromatography because of the bonding capacity apatite surface has for certain proteins and polynucleotides. The metabolic interplay between bone mineral and the body results from the high magnitude and high reactivity of the mineral surface.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 303-312 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new biomaterial for bone substitution, a “machinable bioactive glass-ceramic” has been developed. The material contains two main crystal phases, mica and apatite, and is therefore machinable and bioactive. It has the advantage to be workable by the surgeon, if necessary, during operation. The preparation method of this glass-ceramic is described. Different types of the material can be produced in dependence of the composition, nucleation, and crystallization of the basic glass. In vivo and in vitro investigations showed a characteristic solubility of the material. A Caphosphate-rich interface layer with apatite crystals (from the basic glass-ceramic) and a thickness of about 5-10 μm grows as solid-state reaction between glass-ceramic and bone. This interface reaction is interpreted as a chemical process which includes a slight solubility of the glass-ceramic and a solid state reaction between the stable apatite crystals in the glass-ceramic and the bone.
    Additional Material: 10 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 179-193 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: As a series of studies on the mechanical properties of materials used in cardiac prostheses, static and dynamic characteristics and stability of five kinds of elastomeric polymers have been studied by uniaxial tensile and fatigue tests in air at room temperature and in saline solution at 37°C. Of all materials tested in this study, Texin MD85A, a segmented polyether polyurethane, has the lowest flexibility under static and dynamic conditions, with relatively high strength. Hexsyn, a polyolefin rubber, is highly flexible with little stress relaxation. However, this material has very low tensile strength and short elongation, and shows unstable change in the elastic modulus during cyclic deformation. Avcothane 51, a copolymer of polyurethane and silicon, has unstable mechanical properties and gradually stiffens upon cyclic deformation. On the other hand, Biomer, a segmented polyether polyurethane, has high flexibility and shows the most stable behavior during cyclic deformation regardless of test environment. Toyobo TM5, a similar segmented polyurethane to Biomer, has higher strength and ductility than Biomer, although its static and dynamic flexibility are slightly worse and less stable than those of Biomer. These results indicate that Biomer and Toyobo TM5 are more suitable for flexible components of cardiac prostheses.
    Additional Material: 9 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 233-239 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The sequential cellular reactions in the interface of collagenous bone matrix implants are described. The multistep cascade in response to bone matrix implantation include: binding of fibrin and fibronectin to the implanted matrix, chemotaxis of cells, proliferation of fibroblasts, differentiation into chondroblasts, cartilage formation, vascular invasion, bone formation, remodeling, and bone marrow differentiation. The mechanism of action is not known. However, several properties governing the implantcell interface are described. It is possible that bone matrix is a suitable biomaterial with potential applications in periodontal and orthopedic practice.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 293-301 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Square-shaped implants of various sodium silicate glasses were weighed and implanted intraperitoneally in rats for periods ranging from 8 to about 60 days. The implants were then removed and their aspect was compared to their aspect before exposure to physiological environment. The corrosion products were studied by x-ray diffraction and electron microprobe analysis. Weight changes were also measured to calculate a biodegradation rate. The glass 66 S O (66.6 SiO2-33.3 Na2O) was strongly corroded, as early as after the first week. The nonsoluble degradation products formed a cocoon encapsulating the now smaller specimen. The analysis of the cocoon showed that it was made of a silica-rich layer containing also calcium and phosphorus. In this layer the ratio Ca/P could correspond to that of an apatite. The biodegradation rate reached 71 × 10-4 g · cm-2 · day-1. The glass 75 SO (75 SiO2-25 Na2O) was not so quickly corroded: Cracks appeared at the surface and progressively reached the center of the implants. There was no removable shell but a white deposit, adherent to the surface. This deposit contained silica and also calcium and phosphorus at the periphery. The biodegradation rate was only 2.6 × 10-4 g · cm-2 · day-1.
    Additional Material: 7 Ill.
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  • 7
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interaction of 111Indium-labeled platelets, and other blood components with the luminal surface of polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) was determined using an ex vivo arteriovenous shunt in the baboon. Both PDMS and LDPE showed little platelet accumulation at either high (200 cc/min) or low (25 cc/min) flow rates. PDMS accumulated more platelets at low than at high flow. When the surfaces of PDMS and LDPE were examined under scanning electron microscopy after 2.5 h of flow in the shunt circuit, red and white blood cells were attached. Platelets appeared to be confined to patchy areas covered by a fibrinlike network. The low platelet reactivity of LDPE and PDMS suggests their potential use as coatings for conventional, more platelet reactive, vascular graft materials.
    Additional Material: 10 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 601-605 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 631-642 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Pastes were made by spatulating a hydroxyapatite powder into triethylene glycol dimethacrylate (TEGDMA) that contained benzoyl peroxide. For comparison, similar pastes included 5 wt-% 4-methacryloxyethyl trimellitic anhydride (4-META) in the TEGDMA. Composites were made by heating at 120°C under pressure. Inclusion of 4-META reduced the rate of diffusion of water by about one-third, at 27°C. Also after thermal cycling in water, inclusion of 4-META decreased the fractional drop in compressive strength by about one-half. Examination of fracture surfaces indicated that inclusion of 4-META improved the wetting of filler particles and gave more coherent composites. All these findings are consistent with the view that 4-META acts as a coupling agent.
    Additional Material: 8 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 727-746 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Low-copper amalgams aged at 37°C, 50°C, 60°C, 70°C, and 80°C for periods of 7 and 30 days were examined using a scanning electron microscope and an x-ray diffractometer. Gamma-one Ag-Hg grain size and γ2 Sn-Hg volume fraction, and surface area were determined by quantitative metallography. At 60°C and below, γ1 was the predominant matrix phase. Little β1 Ag-Hg was found. In this temperature range, both γ1 grain size and ADA creep were found to obey an Arrhenius law. A linear relationship was found between the log of the mean ADA creep and the mean γ1 grain size. Above 60°C, the γ1 phases and the majority of the γ Ag-Sn particles disappeared. In their place, β1 appeared. Gamma-two volume fraction increased during aging at temperatures over 60°C, but a coarsening of γ2, reflected in a decrease in γ2 surface area per unit volume, also took place. Aging for 30 days or less resulted in decreases in ADA creep. At 60°C and below, the decrease was caused by increases in γ1 grain size. Above 60°C, the decrease in ADA creep was caused by several factors, one of which was the appearance of large β1 grains.
    Additional Material: 16 Ill.
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