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  • 1
    ISSN: 1572-8935
    Keywords: Epoxy ; Blend ; Polycarbonate ; Transesterification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract PC-DER331 blends are transparent and homogeneous due to the transesterification taking place during hot melting process. This transesterification reaction does not occur or occurs insignificantly during the preparation of PC-DER332 blends. PC is separated from the PC-DER332 melt mixture by slow cooling to room temperature but the mixture remains a single phase by quenching with an ice bath. Two systems of PC-epoxy blends, PC-DER331 blends and PC-DER332 blends are cured by the m-phenylene diamine (MPDA) in a stoichiometric ratio. Curing kinetics have been carried out by differential scanning calorimeter (DSC). The presence of PC accelerates the curing reaction. Infrared spectroscopy (IR) indicates the occurrence of transesterification in the PC-DER331/MPDA blends during curing. The flexural modulus increases with the increase of the PC content while the notched Izod impact strength decreases with the increase of the PC content for all the blending systems. The fracture surfaces of the PC-DER331/MPDA blends are smooth, an indication of a homogeneous morphology. The fracture surfaces of the PC-DER332/MPDA blends are rough, an indication of a heterogeneous morphology.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 29 (1978), S. 161-169 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that the original Marton-type electron interferometer is based on the Fresnel diffraction of two coherent beams by a crystal. The modified Marton-type electron interferometer presented here is based on the Fraunhofer diffraction. The advantages of the proposed interferometer are given in the text along with a simplified sketch of the major components.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Integral equations and operator theory 28 (1997), S. 87-96 
    ISSN: 1420-8989
    Keywords: 47B35 ; 30C40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Calculus of variations and partial differential equations 3 (1995), S. 513-529 
    ISSN: 1432-0835
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, we study energy minimizing harmonic maps into a complete Riemannian manifold. We prove that the singular set of such a map has Hausdorff dimension at mostn−2, wheren is the dimension of the domain. We will also give an example of an energy minimizing map from surface to surface that has a singular point. Thus then−2 dimension estimate is optimal, in contrast to then−3 dimension estimate of Schoen-Uhlenbeck [SU] for compact targets.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Calculus of variations and partial differential equations 3 (1995), S. 513-529 
    ISSN: 1432-0835
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. In this paper, we study energy minimizing harmonic maps into a complete Riemannian manifold. We prove that the singular set of such a map has Hausdorff dimension at most $n-2$ , where $n$ is the dimension of the domain. We will also give an example of an energy minimizing map from surface to surface that has a singular point. Thus the $n - 2$ dimension estimate is optimal, in contrast to the $n - 3$ dimension estimate of Schoen-Uhlenbeck [SU] for compact targets.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 19 (1982), S. 1-8 
    ISSN: 1432-1432
    Keywords: Pre-biotic ; Schiff base ; Amide bond ; Genetic code ; Origin of life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary One hypothesis of the origin of pre-modern forms of life is that the original replicating molecules were specific polypeptides which acted as templates for the assembly of poly-Schiff bases complementary to the template, and that these polymers were then oxidized to peptide linkages, probably by photo-produced oxidants. A double cycle of such anti-parallel complementary replication would yield the original peptide polymer. If this model were valid, the Schiff base between an N-acyl alpha amino aldehyde and an amino acid should yield a dipeptide in aqueous solution in the presence of an appropriate oxidant. In the present study it is shown that the substituted dipeptide, N-acetyl-tyrosyl-tyrosine, is produced in high yield in aqueous solution at pH 9 through the action of H2O2 on the Schiff-base complex between N-acetyl-tyrosinal and tyrosine and that a great variety of N-acyl amino acids are formed from amino acids and aliphatic aldehydes under similar conditions.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theory of computing systems 29 (1996), S. 387-405 
    ISSN: 1433-0490
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In laboratories the majority of large-scale DNA sequencing is done following theshotgun strategy, which is to sequence large amount of relatively short fragments randomly and then heuristically find a shortest common superstring of the fragments [26]. We study mathematical frameworks, under plausible assumptions, suitable for massive automated DNA sequencing and for analyzing DNA sequencing algorithms. We model the DNA sequencing problem as learning a string from its randomly drawn substrings. Under certain restrictions, this may be viewed as string learning in Valiant's distribution-free learning model and in this case we give an efficient learning algorithm and a quantitative bound on how many examples suffice. One major obstacle to our approach turns out to be a quite well-known open question on how to approximate a shortest common superstring of a set of strings, raised by a number of authors in the last 10 years [9], [29], [30]. We give the firstprovably good algorithm which approximates a shortest superstring of lengthn by a superstring of lengthO(n logn). The algorithm works equally well even in the presence of negative examples, i.e., when merging of some strings is prohibited.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theory of computing systems 27 (1994), S. 365-376 
    ISSN: 1433-0490
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We investigate to what extent finite binary sequences with high Kolmogorov complexity are normal (all blocks of equal length occur equally frequently), and the maximal length of all-zero or all-one runs which occur with certainty.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-0832
    Keywords: Aflatoxin-producing ; Aspergillus flavus ; Pectinase-producing ; Sclerotium-producing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Pectinase and sclerotium production by strains ofAspergillus flavus were determined with a pectinase culture plate assay and a Cz 3% NaNO3 medium plate assay. In theA. flavus population, 51% of isolates produced sclerotia, the toxigenic strains showing a tendency to have smaller sclerotia. Strains producing both abundant small sclerotia and a large quantity of aflatoxin were not found. There was no linear correlation between the amount of aflatoxin produced and the number of sclerotia. Levels of pectinase produced by the toxigenic strains were higher than that of the non-toxigenic strains, and this character was more obvious in the sclerotium-producing strains than in the non-sclerotium-prodcing strains. In theA. flavus population from Zhejiang in which the toxigenic strain rate was low, toxigenic strains may require higher levels of pectinase to compete with the non-toxigenic strains when infecting foodstuffs.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Distributed computing 6 (1993), S. 205-209 
    ISSN: 1432-0452
    Keywords: Time-stamps ; Bounded protocols ; Precedence relation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Summary Time-stamps are labels which a system adds to its data items. These labels enable the system to keep track of the temporal precedence relations among its data elements. Many distributed protocols and some applications use the natural numbers as time-stamps. The natural numbers however are not useful for bounded protocols. In this paper we develop a theory ofbounded time-stamps. Time-stamp schemes are defined and the complexity of their implementation is analyzed. This indicates a direction for developing a general tool for converting time-stamp based protocols to bounded protocols.
    Type of Medium: Electronic Resource
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