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  • Polymer and Materials Science  (3)
  • anaerobic  (2)
  • 1995-1999  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Biological degradation of Ascophyllum nodosum (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 347-357 
    Details
    ISSN: 1573-5176
    Keywords: brown seaweed ; aerobic ; anaerobic ; alginate ; lyase ; polyphenols ; formaldehyde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The alginate forms the major structural component of the cell wall and the intercellular matrix of the brown alga Ascophyllum nodosum. Successful biological degradation of A. nodosum would largely depend on the dissolution of the alginate, but reactive compounds in the alga such as polyphenols may also have toxic effects on the microbial population involved. Aerobic and anaerobic batch reactors, operated at 35°C and pH 7, were fed milled A. nodosum, nutrients and inocula adapted to seaweed degradation. The dominant factor for conversion of organic matter during anaerobic digestion was the inhibitory effect of the polyphenols on alginate lyases and methane production. Probably, the relative large fraction of high molecular weight polyphenols (〉10 kDa) in this alga gave efficient binding of proteins during digestion. The anaerobic degradation was greatly stimulated when the polyphenols were fixed with low amounts of formaldehyde. An accumulated content of guluronate in the remaining alginate indicated that Ca-crosslinking also limited the guluronate lyase access to the polymer. In contrast, the aerobic digestion of alga gave no increase in the guluronate content of the residual alginate. Compared to anaerobic conditions, the phenols had a much lower influence on the hydrolytic rate of organic matter during aerobic conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007988712929
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  • 2
    Electronic Resource
    Electronic Resource
    Alginate degradation during anaerobic digestion of Laminaria hyperborea stipes (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 157-166 
    Details
    ISSN: 1573-5176
    Keywords: seaweed ; anaerobic ; degradation ; Laminaria hyperborea ; alginate ; lyase ; polyphenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polyphenols and divalent metal ions present in the tissue may seriously affect the degradation of alginate during anaerobic digestion of brown seaweeds. Laminaria hyperborea stipes, harvested at 59 °N off the Norwegian coast in the autumn, were degraded at different concentrations of polyphenols in anaerobic batch reactors at 35 °C and pH 7. This was done by removing or adding the mechanically peeled outer phenolic layer of the algae, and using methanogenic and alginate degrading inocula already adapted to L. hyperborea degradation. Initial alginate released from the algal particles was affected by NaOH titrations because the Ca/Na-ratio was reduced. After a rapid consumption of the mannitol, alginate lyases were induced, and guluronate lyases showed the highest extracellular activity. Then the microbes digested 0.12–0.23 g Na-alginate L−1 h−1. Later the degradation rate of alginates declined almost to zero, and 13–50% of the alginate remained insoluble. The total solubilisation of alginates was apparently limited by both Ca-crosslinked guluronate residues and complexation with compounds such as polyphenols. The methane production had a lag phase that increased at higher amounts of soluble polyphenols, and the total fermentation probably also became product inhibited if soluble compounds such as acetate, ethanol and butyrate were accumulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007966126570
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical imaging by scanning force microscopyWe thank R. Kranwctvogcl for support during the preparation of tip and sample. (1995)
    Weinheim : Wiley-Blackwell
    Advanced Materials 7 (1995), S. 549-551 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19950070607
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  • 4
    Electronic Resource
    Electronic Resource
    Zur Korrosion von Reinaluminium in strömender Salpetersäure (1996)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 47 (1996), S. 323-332 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Corrosion of pure aluminium in flowing nitric acidAfter 10 to 15 years in use under operating conditions, piping systems made of Al-99.5 in which highly concentrated nitric acid was flowing at a flow rate of 1 m/s exhibited flow-induced corrosion patterns.In corrosion tests involving single phase flow, no relationship could be found between flow and corrosion of Al-99.5 in nitric acid of various concentrations. The following testing methods were used: rotating disks of various configurations, rotating cylinders, and flow inside a tube.The influence of two-phase flow generated by a special mixing turbine resulted in weight losses of Al-99.5 with respect to nitric acids having concentrations of 90 to approximately 100%. In the Arrhenius diagram, the temperature dependence of the data with practically represent anhydrous nitric acid is shown as a scatter band. Lower nitric acid concentrations are shifting the scatter band in the direction of higher corrosion rates.
    Notes: In der Praxis wurden nach mehrjähriger Betriebsdauer  -  nach 10 bis 15 Jahren  -  strömungsinduzierte Korrosionsmerkmale an hochkonzentrierte Salpetersäure führenden Rohrleitungen aus Reinaluminium Al 99,5 beobachtet; die Fließgeschwindigkeiten lagen bei 1 m/s.Bei Korrosionsprüfungen war in einphasigen Strömungen keine Strömungsabhängigkeit der Korrosion von Al 99,5 in Salpetersäure unterschiedlicher Konzentration nachweisbar, wobei folgende Prüfmethoden herangezogen wurden: rotierende Scheiben unterschiedlicher Form,rotierende Zylinder unddurchströmtes Rohr.Nur in zweiphasigen Strömungen, die mit Hilfe einer speziellen Mischturbine erzeugt wurden, ergaben sich  -  bezogen auf ruhende Werkstoffproben  -  erhöhte Massenverluste für Al 99,5 in 90 bis rd. 100% iger Salpetersäure. Die Temperaturabhängigkeit der für praktisch wasserfreie Salpetersäure geltenden Meßwerte zeigt sich im Arrhenius-Diagramm in Form eines Streubandes. Geringere Salpetersäure-Konzentrationen bewirken eine Parallelverschiebung des Streubandes in Richtung höherer Abtragungsgeschwindigkeiten.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19960470605
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  • 5
    Electronic Resource
    Electronic Resource
    Poly[n]acene precursors via repetitive Diels-Alder reactions with dehydrobenzenes (1995)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 196 (1995), S. 2463-2474 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Due to their instability, higher [n]acenes are even poly[n]acenes are still elusive in solution. In the present paper the synthesis of new poly[n]acene precursors (7, 9) is described from which the fully aromatic structures should be available by pyrolysis in the solid state via cycloreversion. Polymer syntheses were carried out via repetitive Diels-Alder reaction of a bicyclic bis-diene precursor with dehydrobenzenes. Repetitive [4 + 2]cycloaddition was employed because of its potential for constructing defect-free ladder-type polymers. Arynes have only been used once before in the actual polymerization step of a polymer synthesis, but this case involved an AA-type diazotated anthranilic acid. The present approach deals with AB-type monomers containing dehydrobenzenes as active dienophilic species prepared from dibromobenzenes with butyllithium at low temperatures (-40°C). Aromatization of the precursor polymers 6 and 8 with tetrachloro-p-benzoquinone provides the aromatized polymers 7 and 9 interrupted only by the bicyclo[2.2.2]octadiene resp. -triene units.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1995.021960804
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