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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 263 (1985), S. 799-803 
    ISSN: 1435-1536
    Keywords: Biopolymers ; thermoplastics ; dynamic modulus ; X-ray scattering ; mechanical anisotropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Dynamic tensile modulus and X-ray scattering measurements were made for a series of bacterially produced poly-Β-hydroxybutyrate/Β-hydroxyvalerate (PHB/HV) random copolymers. The position of the primary relaxation is shifted to lower temperatures by increasing HV content and the material becomes generally softer. Drawn PHB/ 17% HV copolymer shows conventional mechanical anisotropy. Results are presented comparing the dynamic mechanical behaviour of isotropic PHB/HV with that of conventional thermoplastics such as polyethylene terephthalate, isotactic polypropylene and polyethylene.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 263 (1985), S. 116-119 
    ISSN: 1435-1536
    Keywords: Electron microscopy ; staining ; morphology ; nylon-12 ; orientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The morphology of drawn and annealed sheets of nylon-12 was investigated by transmission electron microscopy of stained sections, and the results compared with equivalent small-angle X-ray scattering (SAXS) patterns. A three-component structure was observed, consisting of crystalline (C) and amorphous (A) regions in the microfibrils and an interfibrillar component whose density was deduced to be intermediate between that of the C and A regions. The crystallite width was given satisfactorily by a Guinier analysis of the SAXS profile.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 263 (1985), S. 991-996 
    ISSN: 1435-1536
    Keywords: Segmented polyurethane elastomers ; platelet domains ; infrared dichroism ; dynamical mechanical measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract As a result of infrared dichroism and dynamic mechanical measurements on segmented polyurethane elastomers during orientation, a model is suggested for the orientation behaviour based on shear of the soft segment matrix. The hard segment domains are assumed to behave as indeformable platelets which determine the matrix shear plane in their vicinity. On extension of the elastomer, the platelets rotate into the stretch direction by shear of the matrix. The behaviour of the dynamic compliance on stretching is determined at each stage of the deformation by the platelet orientation corresponding to the superimposed static strain. This model provides a better description of the orientation behaviour than given by a pseudo-affine transformation of domains.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 263 (1985), S. 435-442 
    ISSN: 1435-1536
    Keywords: Cooperative relaxation ; elementary softening ; thermally stimulated schrinkage ; thermo-mechanical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thermally stimulated recovery behaviour of amorphous polymers is described in terms of a continuous distribution of sharply defined elementary softening processes in the polymer. It is proposed that each of these elementary processes is the result of a co-operative site-change mechanism. On exceeding the activation temperature for the process, the viscoelastic time constants fall abruptly by many orders of magnitude, as opposed to following an Arrhenius-type law. The implications of this type of behaviour are discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 19 (1990), S. 143-147 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Leachate from municipal landfills represents a potential health risk to both surrounding ecosystems and human populations. Landfill leachate collected from a site in New Jersey was evaluated for its anaerobic biodegradability and toxicity to methanogenesis using two anaerobic bioassays. Chemical characterization of the leachate yielded the following results (mg/L): chemical oxygen demand (COD)=6478; dissolved oxygen (DO)=1.8–2.0; oil and grease=4.8; suspended solids=5.6; total Kjeldahl nitrogen (TKN)=215; total phosphorus=1.53; biochemical oxygen demand (BOD)=73 and pH=7.0–7.4. Anaerobic biodegradation of leachate as the sole source of carbon yielded methane production values greater than background over extended incubation periods with increasing concentration. However, increased concentrations of leachate produced a decrease in recovery of methane per kg COD amended. In a second assay, leachate toxicity was assessed by monitoring the suppression of methanogenesis in acetate and propionate amended cultures. Results of these assays indicate that concentrations of leachate greater than 10% produced a significant irreversible suppression of methanogenesis, while concentrations less than 10% showed enhanced methane production above background and active control. These results suggest that the leachate from this site contains a biodegradable fraction which can be partially mineralized under methanogenic conditions over extended periods of incubation. However, high concentrations in excess of 10% may be inhibitory to anaerobic methanogenic processes.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 25 (1993), S. 285-291 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Monosubstituted nitro- and aminophenol isomers exhibited limited biodegradability under methanogenic conditions when supplied as the sole source of carbon and energy. This was examined by supplying to the same sediment samples, each isomer of nitro- and aminophenol as a sole source of added carbon under either N-supplemented or N-deprived methanogenic conditions. The results demonstrated that under N-supplemented conditions, only 2-NP (NP=nitrophenol), 4-NP and 4-AP (AP=aminophenol) were stoichiometrically mineralized, 2-AP, 3-AP, and the 3-AP metabolite formed from 3-NP reduction were persistent over the 51-week incubation period. In addition, NP isomers inhibited initial rates of methanogenesis, while all AP amended cultures exhibited no significant inhibition in the rate of methanogenesis. Under N-deprived conditions, 2-NP, 2-AP and 4-AP were mineralized, while 3-NP, 4-NP and 3-AP were persistent over the 51-week incubation period. Although all NP isomers were still metabolized through the corresponding AP isomer, the deprivation of nitrogen significantly depressed both the rate and extent of methanogenesis. In general, nitrogen supplemented cultures produced 25% more methane than the nitrogen limited cultures, and the initial rates of methanogenesis were four times greater. While these data showed that under N-deprived conditions methanogenesis was inhibited to a greater extent by these compounds, it also suggests that N-deprived conditions may have facilitated the establishment of a 2-AP metabolizing consortium.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 16 (1981), S. 2324-2326 
    ISSN: 1573-4803
    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
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 22 (1987), S. 3602-3606 
    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 d.c. conductivity measurements have been made in a wide range of temperature on a basalt glass heat-treated at different temperatures to form magnetite particles. Small polaron hopping mechanism is operative in the as-annealed glass between Fe2+ and Fe3+ ions in the isolated state. This mechanism is operative in the heat-treated samples between these ions in the magnetite grains. The d.c. conductivity at 473 K and the activation energy show significant changes around 700° C, when magnetite forms in the basalt glass, which has been correlated with the magnetic data on these samples. TSPC and TSDC data are interesting, but the data analysis is complicated by the possible occurrence of Verwey transition in the small particles of magnetite. Preliminary a.c. conductivity data support the small polaron hopping mechanism.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 6 (1971), S. 485-489 
    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 anisotropy of the elastic modulus of specially prepared sheets of drawn, rolled and annealed low-density polyethylene has been analysed quantitatively. These materials were regarded as two-phase composites of crystalline and amorphous regions, in which the interlamellar regions of the polymer were assumed to deform under load by both pure shear and simple shear mechanisms. The anisotropy of the a–b and parallel lamellae structures agrees well with the predictions of this simple theory.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Bioscience reports 6 (1986), S. 759-766 
    ISSN: 1573-4935
    Keywords: Carica papaya ; Caricaceae ; proteinase ; monoclonal antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The proteinases fromCarica papaya include papain, isoenzymes of chymopapain and two proteinases A and B distinguished by their unusually high pI. The identity of one of the most basic proteinases has been questioned. The present report describes the preparation and characterisation of two monoclonal antibodies that react specifically with papaya proteinases A and B respectively and a third that identifies a common structural feature found in papain and proteinase A.
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