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  • 1995-1999  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 32 (1998), S. 297-308 
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Birch wood meal was phenolated in the presence of sulfuric acid used as a catalyst by changing several reaction conditions, such as, phenol-to-wood ratio, temperature, time, and catalyst concentration to make novolak-type resin. A phenol-to-wood ratio of 2–5, reaction temperature of 60–150 °C, time of 60–120 min, and acid concentration of 1–3% were found to be usable values for obtaining good enough amounts of combined phenol and less amounts of unreacted wood residue. The flow properties (flow temperature and apparent melt-viscosity) of the phenolated wood obtained increased with the increase in the amount of combined phenol, however, decreased with the increase in the moisture content and free phenol in the phenolated wood. Furthermore, it was found that the solubility of the phenolated wood in the organic solvents depended, greatly, on the hydrogen bonding strength of the solvents.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 30 (1995), S. 39-47 
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Birch (Betula maximowicziana Regel) wood meal was liquefied in the presence of phenol using hydrochloric acid (HCl) as a catalyst at a temperature of 150 °C for 2 h in an autoclave. It was found out that HCl acid could be used as an effective catalyst for the hydroxy phenylation of wood under the experimental conditions. In this study the effect of the concentration of the acid catalyst and the phenol-to-wood ratio on the liquefaction were investigated. The results showed that the phenol-to-wood ratio and the concentration should be increased to a certain degree in order to achieve a less residual rate and sufficient amount of combined phenol. The phenolated woods had apparent flow temperatures in the range of 134.4 to 199.8 °C, being higher than that of a commercial novolak resin. Furthermore, increases in the HCl concentration during liquefaction reaction led to increase in the apparent flow temperature of the resulting phenolated woods. However, the changes in the liquid ratio did not bring about evident changes. The relationship between shear stress (τ) and shear rate $$\dot \gamma $$ showed that the phenolated wood resin melts were shear thinning fluids. The dependences of the apparent melt-viscosities (η) of the phenolated woods and a commercial novolak resin on the shear rates ( $$\dot \gamma $$ ) have the similar tendencies, however, it was found the viscosities of the phenolated woods are about one order higher than that of commercial novolak resin.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Rhizomucor pusillus 1116R3 has a defect in alg2 encoding a mannosyltransferase in the asparagine (N)-linked oligosaccharide biosynthetic pathway and produces proteins in less-glycosylated forms. For development of a genetic transformation system for this zygomycete, an uracil auxotroph (mutant 1116U17) as the host strain was derived by ultraviolet (UV) mutagenesis as 5-fluoroorotic acid-resistant colonies and the orotidine-5′-monophosphate (OMP) decarboxylase (pyr4) gene as a selection marker was cloned from the wild-type strain R. pusillus F27 by the polymerase chain reaction with primers designed on the basis of the pyr4 sequences from other fungi. The amino acid sequence of R. pusillus Pyr4 deduced from the nucleotide sequence showed high homology with the OMP decarboxylases from various fungi. The pyr4 gene on pUC19 (plasmid pRPPyr4) was introduced into protoplasts of R. pusillus 1116U17 by polyethylene glycol-assisted transformation. Transformation under optimized conditions yielded 5 Ura+ transformants with 1 μg pRPPyr4 DNA and 1 × 107 viable protoplasts. Southern blot analysis of the genomic DNA from the transformants showed that multiple copies of the pRPPyr4 sequence were integrated into the genome by homologous recombination at the pyr4 locus. For the purpose of production of a milk-clotting aspartic proteinase (MPP) in a less-glycosylated form, mpp from the wild-type strain was cloned in pRPPyr4 and introduced into protoplasts of R. pusillus 1116U17. Transformants obtained in this way contained multiple copies of mpp at the chromosomal mpp locus and produced MPP as a mixture of molecules having no sugar chains and Man0∼1GlcNAc2 at the two N-linked glycosylation sites in an amount about 12 times larger than the parent strain. The transformation system for R. pusillus 1116U17 would be useful for production of proteins with truncated N-linked oligosaccharide chains.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 32 (1998), S. 297-308 
    ISSN: 0043-7719
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Birch wood meal was phenolated in the presence of sulfuric acid used as a catalyst by changing several reaction conditions, such as, phenol-to-wood ratio, temperature, time, and catalyst concentration to make novolak-type resin. A phenol-to-wood ratio of 2–5, reaction temperature of 60–150 °C, time of 60–120 min, and acid concentration of 1–3% were found to be usable values for obtaining good enough amounts of combined phenol and less amounts of unreacted wood residue. The flow properties (flow temperature and apparent melt-viscosity) of the phenolated wood obtained increased with the increase in the amount of combined phenol, however, decreased with the increase in the moisture content and free phenol in the phenolated wood. Furthermore, it was found that the solubility of the phenolated wood in the organic solvents depended, greatly, on the hydrogen bonding strength of the solvents.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Holz als Roh- und Werkstoff 56 (1998), S. 245-246 
    ISSN: 1436-736X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 675-683 
    ISSN: 0021-8995
    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
    Notes: Birch wood meal has been phenolated in the presence of oxalic acid alone or its mixture with hydrochloric acid (HCl) at various temperatures ranging from 150 to 250°C under high pressure. The effects of high temperature, high pressure, and the addition of HCl in conjunction with oxalic acid on the amounts of wood residue and combined phenol have been investigated. In the case of the oxalic acid-catalyzed process, by increasing reaction temperature from 180 to 250°C, the amounts of wood residue could be considerably reduced, but the amount of combined phenol decreased. In comparison to a noncatalyzed process in the absence of water, the catalyzed one offered a relatively lower amount of wood residue and a higher amount of combined phenol. However, compared to a noncatalyzed process with water, particularly at a high temperature of 250°C, the catalyzed process gave significantly larger amounts of wood residue. In addition, with a small addition of HCl to an oxalic acid catalyzed system, the amount of wood residue was remarkably reduced compared to that of oxalic acid alone, and the amount of combined phenol could be increased significantly. Furthermore, the mechanical properties of the moldings prepared from the phenolated wood were sufficiently improved by the addition of a small amount of HCl to the oxalic acid-catalyzed system. © 1996 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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