ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    In:  Tectonophys., Edmonton, Conseil de l'Europe, vol. 94, no. 2, pp. 327-348, pp. B10410, (ISSN: 1340-4202)
    Publication Date: 1983
    Keywords: Velocity depth profile ; CRUST ; Tectonics ; Deep seismic sounding (espec. cont. crust)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    facet.materialart.
    Unknown
    In:  J. Geophys. Res., Luxembourg, EGS-Gauthier-Villars, vol. 90, no. 23, pp. 10223-10236, pp. L23303
    Publication Date: 1985
    Keywords: Earthquake precursor: prediction research ; JGR
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 31 (1996), S. 3349-3359 
    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 It has been found that well-defined fluorescence R1 and R2 lines can be obtained from PRD-166 alumina-zirconia fibres and that the fluorescence R lines shift with applied stress. They are found to shift to higher wavenumber when subjected to tensile deformation and to lower wavenumber in compression. The stress-sensitive fluorescence R2 line has been used to map the distribution of stress along PRD-166 fibres embedded in an epoxy resin matrix cured under different conditions. It has been shown that the distributions of stress along the PRD-166 fibres at different levels of matrix strain are consistent with those predicted by conventional shear-lag analysis. The interfacial shear stress has been derived from the point-to-point variation of stress along the fibre. The fluorescence technique has also been used to map the stress distribution along a PRD-166 fragment in an epoxy matrix during a single-fibre fragmentation test where it is found that debonded regions propagate along the fibre fragments during loading, after initial fragmentation has occurred.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 31 (1996), S. 3893-3913 
    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 Many attempts have been made to measure, evaluate and improve the level of interfacial adhesion in aramid/epoxy composites. Different surface treatments have been developed in order to promote chemical bonding between the fibre and the matrix but it is found that most of the surface treatments developed have shown little or no improvement in the level of interfacial adhesion. The interfacial properties of a model composite are often determined by measuring the interfacial shear strength using micromechanical test methods that employ different loading configurations. However, the values of interfacial shear strength determined using different test methods are found to be dependent upon the variation of localized stress in the samples due to the different loading configurations and often give different results. Using Raman spectroscopy it is shown that the strain-dependent shift of the 1610 cm−1 aramid Raman band can be used to determine the point-to-point variation of axial fibre strain along aramid fibres embedded in epoxy resin matrices from which the interfacial properties can be derived. The interfacial properties of aramid/epoxy model composites have been determined using Raman spectroscopy where the properties of the fibre, including different surface treatments, and the matrix have been changed systematically. The results are reviewed here and compared to those obtained using conventional micromechanical test methods. It is also demonstrated that the Raman technique can be used to characterize the interfacial properties of aramid/epoxy model composites deformed using different micromechanical test methods. In this way the interfacial properties can be determined at different loading levels enabling the progressive failure of the fibre/matrix interface to be monitored and defined accurately.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 30 (1995), S. 5607-5616 
    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 Raman spectroscopy has been used to monitor the state of axial stress along fragmented, high-modulus Kevlar 149 aramid fibres in an epoxy resin matrix by monitoring the peak position of the strain-sensitive 1610 cm−1 aramid Raman band along individual fragments. It is shown that the interfacial shear stress along each fragment, derived from the strain distribution profiles, is not constant as assumed by conventional fragmentation analysis. The fragmentation process of as-received Kevlar 149 fibres is compared to that of irradiated Kevlar 149 fibres exposed to ultraviolet light where the tensile strength and modulus of the fibres have been reduced. It is found that the derived interfacial shear stress and interfacial shear strength values are higher for those fibres exposed to ultraviolet light compared with the as-received fibres. It is also clearly demonstrated that the values of interfacial shear strength calculated at high matrix strains from conventional fragmentation analysis are considerably lower than the maximum value of interfacial shear stress prior to fibre fracture that was found to be close to the shear yield stress of the resin matrix. Hence the determination of the interfacial shear strength following the saturation of the fragmentation process may give rise to misleading results.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 11 (1992), S. 1344-1346 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 24 (1993), S. 539-544 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is demonstrated that Raman spectroscopy can be used to study both the deformation micromechanics of high-performance aramid polymer fibres and of these fibres in model, single-fibre epoxy resin matrix composites. It is shown that the peak position of the 1610 cm-1 aramid Raman band shifts to lower frequency under the action of tensile stress or strain due to the macroscopic deformation leading to direct stretching of the polymer molecules. These strain-induced band shifts can be used to map the distribution of stress or strain along a discontinuous, aramid fibre inside an epoxy resin matrix from which the interfacial shear stress can be calculated. It is shown that the behaviour is consistent with that predicted by the classical shear-lag analysis. The technique was also used to study the fragmentation process for an aramid fibre in an epoxy resin matrix in which the matrix strain exceeds the failure strain of the fibre. It is further demonstrated that the technique can be used to compare the interfacial properties of aramid fibres where the interfacial shear stress is found to be higher for sized fibres than for those which have been de-sized.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
  • 9
    Publication Date: 1996-08-01
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2019
    Description: 〈p〉Macrocycles, compounds containing a ring of 12 or more atoms, find use in human medicine, fragrances, and biological ion sensing. The efficient preparation of macrocycles is a fundamental challenge in synthetic organic chemistry because the high entropic cost of large-ring closure allows undesired intermolecular reactions to compete. Here, we present a bioinspired strategy for macrocycle formation through carbon–carbon bond formation. The process relies on a catalytic oligomer containing α- and β-amino acid residues to template the ring-closing process. The α/β-peptide foldamer adopts a helical conformation that displays a catalytic primary amine–secondary amine diad in a specific three-dimensional arrangement. This catalyst promotes aldol reactions that form rings containing 14 to 22 atoms. Utility is demonstrated in the synthesis of the natural product robustol.〈/p〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...