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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Materials research innovations 3 (2000), S. 250-262 
    ISSN: 1433-075X
    Keywords: Key words Small-specimen testing ; Controlled-flaw method ; Fracture toughness ; Brittle materials ; Finite element analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: ∞ is the crack resistance at ”infinite” crack length. It is convincingly shown that this so-called R-curve equation correctly predicts K∞, which is comparable to the conventionally measured Mode I plain-strain fracture toughness, KIc, of the same material. The fundamental constants in the fracture-mechanics-based equations are discussed, emphasizing the aspects pertinent to the small specimens used in the MDBT. Results are presented on 8 materials: ZnS, glass-ceramic, Si3N4, Ti5Si3, SiC, Ni3Ge, NiAl and Ti-46.5A1-2.1Cr-3.0Nb-0.2W. All are brittle except for the latter two, which undergo slight plastic deformation before fracturing. The resulting values of K∞ are in excellent agreement with published values derived from conventional measurements, providing considerable confidence in the method. where Q is a constant and K∞ is the crack resistance at ”infinite” crack length. It is convincingly shown that this so-called R-curve equation correctly predicts K∞, which is comparable to the conventionally measured Mode I plain-strain fracture toughness, KIc, of the same material. The fundamental constants in the fracture-mechanics-based equations are discussed, emphasizing the aspects pertinent to the small specimens used in the MDBT. Results are presented on 8 materials: ZnS, glass-ceramic, Si3N4, Ti5Si3, SiC, Ni3Ge, NiAl and Ti-46.5A1-2.1Cr-3.0Nb-0.2W. All are brittle except for the latter two, which undergo slight plastic deformation before fracturing. The resulting values of K∞ are in excellent agreement with published values derived from conventional measurements, providing considerable confidence in the method.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Protein Incorporation ; Amino Acids ; p-Bromophenylacetylurea ; Neuropathy ; Neurotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The incorporationin vivo of14C-glycine into proteins has been studied during the period before and after the onset of neurotoxicity caused by an organic mercury compound and byp-bromophenylacetylurea in rats. The observations of Yoshinoet al. (1966) on the former intoxication have been confirmed in that an impairment of glycine incorporation into proteins was present in spinal ganglion cells, and may also be taking place in other tissues, before nerve fibre degeneration takes place. A similar reduction in amino acid incorporation into proteins during the period before the onset of paralysis due top-bromophenylacetylurea is found in spinal ganglia; this finding is confirmed by anin vitro method using14C-leucine as protein precursor.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 19 (1971), S. 208-215 
    ISSN: 1432-0533
    Keywords: Organic Mercury ; Neuropathy ; Toxicology ; Neuronal ; Degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rats have been poisoned with methyl-mercury-dicyandiamide at two different dose levels, 5 mg/kg body weight or 7.5 mg/kg daily for 8 consecutive days. The morphological changes in peripheral nerves and the central nervous system are largely restricted to primary sensory cells of spinal ganglia, and to a lesser extent to the granular cells of the cerebellum. There were clearly two grades of cell damage, either whole cell death or whole fibre death; there is no evidence to suggest that partial fibre death could occur, at least not at the two dose levels used. No definite indications were found for this neuropathy being a ‘dying back’ process, for the nerve fibres appeared to degenerate contemporaneously along their whole extent.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 15 (1969), S. 680-685 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mechanism of solid state polycondensation has been subjected to a fundamental analysis. Equations were formulated for combined diffusion and chemical reaction for two separate situations. One was for solid state polycondensation in polymer flakes or chips. The other dealt with polymer powders. The resultant solutions related molecular weight changes to rate functions. A technique for deriving the rate functions from experimental data is described.Solid state polycondensations were then studied for nylon 66, nylon 6-10, and polyethylene terephthalate. These data which ranged from 120 to 200°C. were tested with various mechanisms. The most appropriate one was found to be that developed in the present work. Chemical reaction was found to be the rate controlling step in solid state polycondensation in nylon 66, polyethylene terephthalate, powders of nylon 6-10 and larger particles of nylon 6-10 at and above 160°C. Diffusion of byproduct through the solid was the rate controlling step for larger particles of nylon 6-10 at temperatures below 160°C. Thermograms of nylon 6-10 indicated morphological changes which possibly influenced the behavior of the larger nylon 6-10 particles. The Arrhenius relation was fitted to the situations where chemical reaction controlled.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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