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  • 1
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fine spherical particles with various diameters (70, 160 and 40 nm, and 35, 65 and 125μm) were mixed with isotactic polypropylene (PP). For the oriented composites having hexagonal symmetry produced by drawing, the elastic properties were determined by five compliances,S, or stiffness constants,C. Four of these, namely,S 33,S 11,S 13 andS 44 (orC 33,C 11,C 13 andC 44) were determined for the oriented composites filled with particles whose average diameters were 7 nm and 65μm. For the composites filled with the smaller particles (7 nm), all the stiffness constants (C 33,C 11,C 13 andC 44) increased with the filler content, whereas for those with larger particles (65μm), this relation was reversed. The Young's moduli of the oriented composites filled with relatively small particles (7, 16 and 40 nm) in each re-stretching direction increased with increasing filler content and with decreasing filler size, whereas those of the composites filled with larger filler (35, 65 and 125μm) decreased with increasing filler content and size. It was concluded that the modulus of the oriented composite is determined by three factors, namely: (1) molecular orientation of matrix polymer; (2) the volume-fraction and size of filler; and (3) the fraction of void introduced by drawing. The moduli observed for the oriented composites are well explained by an equation derived on an assumption of the independence of the three effects. It was also concluded that extremely small fillers with particle sizes comparable to that of the crystalline region in PP matrix have a prominent reinforcing effect in the oriented polymer matrix.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: The determination of the calcium to phosphate ratio (Ca/P) in Ca-deficient hydroxyapatite [d-HAP; Ca10−x (HPO4) x (PO4)6−x (OH)2−x ] using X-ray diffraction analysis (XRD) is reported. At temperatures above 700°C HPO4 2- groups are transformed to PO4 3- groups, thereby producing β-tricalcium phosphate [β-TCP; Ca3(PO4)2]. Thus, the deviation from stoichiometry, x, can be calculated from the mass fraction of β-TCP, which in turn can be determined from quantitative XRD analyses. In this study d-HAP powders with various Ca/P ratios were prepared following several procedures. It is shown that the Ca/P ratio determined by quantitative XRD correlates well with that measured by chemical analyses.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 9 (1990), S. 400-402 
    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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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 9 (1974), S. 737-743 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The stress wave energy released from notched specimens of structural steel was measured in order to compare it with the recently proposedJ-integral which takes account of the effect of large plastic deformation around the crack tip in ductile materials. Very close agreement was observed between theJ-integral and the differential stress wave energy released. This suggests that the increment of the stress wave energy released is proportional to the decrement of the work done on the specimen during tensile testing under the plane stress condition. This result, combined with information obtained from linear elastic fracture mechanics, leads to a relationship between the differential stress wave energy released and the stress intensity factorK, [Δ(SWER)/Δa] ∝K 2. It was also found that in the region before general yielding, the stress wave energy release was proportional to the development of plastic zone size. A larger portion of the accumulated stress wave energy released was generated after general yielding due to void formation and coalescence. The accumulated stress wave energy released at the catastrophic crack growth point reached virtually the same value for each specimen, independent of the initial crack length. This implies that void formation and coalescence are not influenced by the initial crack length, but by the geometry of the crack tip.
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  • 6
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Abstracts are not published in this journal
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  • 7
    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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  • 8
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A non-decay type fast-setting calcium phosphate cement (nd-FSCPC) has been described, which did not decay but set within approximately 5–6 min even when the paste was immersed in serum immediately after mixing, and which forms hydroxyapatite as its end product. nd-FSCPC was produced by adding sodium alginate to the liquid phase of the base cement FSCPC. Sodium alginate forms a water-insoluble gel, and reduces the process of fluid penetration into the paste which is the cause of decay. The aim of this investigation was to confirm the mechanism of the non-decaying behaviour of nd-FSCPC proposed in a previous paper, using another chemical with properties similar to those of sodium alginate. Also, it was intended to further improve both the mechanical properties and tissue response of nd-FSCPC. Chitosan, which also forms a water-insoluble gel in the presence of calcium ions and has been reported to have pharmacologically beneficial effects on osteoconductivity, was added to the liquid phase of the base cement FSCPC. The cement thus prepared showed behaviour similar to that of nd-FSCPC using sodium alginate. The cement paste did not decay but set within approximately 5–6 min even when immersed in serum immediately after mixing. DTS value of the set mass was approximately 3–4 MPa, slightly lower than that of nd-FSCPC using sodium alginate, and no inhibitory effect was observed for the transformation of cement component to apatite within the range used in this investigation (up to 1.5%). Therefore, it was concluded that the mechanism of non-decaying behaviour was, at least in part, reduction of fluid penetration into the cement paste. nd-FSCPC using chitosan showed slightly poorer mechanical properties than that using sodium alginate. However, pharmacological effects such as osteoconductivity could be expected in nd-FSCPC using chitosan. Thus, this cement may be useful as a more sophisticated bioactive cement than nd-FSCPC using sodium alginate.
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  • 9
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dynamics of two dimensional electrons under the strong perpendicular magnetic field is shown to be described by a multi-component fermion theory. The electric conductance has a remarkable property known as the quantum Hall effect. The Hall conductance is quantized in units ofe 2/h in the gap region and in the localized state region. The proof of exactness is presented in general cases using quantum field theory.
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 98 (1976), S. 5697-5699 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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