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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 28 (1993), S. 9-22 
    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 Finely ground spruce wood (Picea abies (L.) Karst.) was incubated with various commercial enzyme preparations; the incubation liquid was analysed for the presence and volume of uronic acids and neutral sugars. The tested enzyme preparations dissolved neutral and acid sugar from the woodpowder. The most effective enzyme preparations were cellulolytic enzymes with some hemicellulolytic activites. This applied to the decomposition of neutral polysaccharide as well as to polyuronide. The polysaccharides in the cell wall were almost completely broken down to low molecular weight sugars by these preparations. Pectinase preparations, on the other hand, had lower efficacy in decomposing neutral and acid polysaccharides. A difference in efficacy of the enzyme preparations in decomposing heart- or sapwood could not be ascertained.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 32 (1998), S. 347-365 
    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 The penetration characteristics of five modern wood coatings (three waterborne, one high solid and one solvent borne) into pine sapwood, spruce and dark red meranti have been systematically compared. The degree of coating penetration is mainly determined by the ability of the coating to flow into wood capillaries. Binder type, pigmentation, solid matter content and drying speed appeared to influence this ability. In softwoods the following different coating penetration routes are observed: the flow into open ends of longitudinal early-and latewood tracheids, the flow into ray cells and the transport from rays through the cross-field into longitudinal tracheids adjacent to rays. The possibility for the coating to follow the latter route is strongly influenced by the existing type of cross field pitting and to a lesser degree by the pigmentation of the paint. Clear differences between pine and spruce have been found with respect to the flow into ray parenchym and ray tracheids. The flow into open ends of longitudinal tracheids is strongly influenced by the grain angle of tracheids. Penetration into dark red meranti is mainly limited to vessels and rays. Tylose membranes can prevent the complete filling of vessels. The impact on penetration of the removal of extractives and of sanding of the surface has also been studied but appears to be of only minor importance.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 27 (1993), S. 347-355 
    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 European Beech (Fagus silvatica L.) was impregnated with a dimethylol resin to improve its dimensional stability and durability. Different catalysts were evaluated in combination with the resin. Depending on the range of relative humidity, the resin improved the shrinkage and swelling by approximately 50%. The use of an acid (citric or tartaric) catalyst lead to improved resin curing. A curing temperature of 100 °C is necessary.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Holz als Roh- und Werkstoff 56 (1998), S. 306-306 
    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
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 32 (1998), S. 347-365 
    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 The penetration characteristics of five modern wood coatings (three waterborne, one high solid and one solvent borne) into pine sapwood, spruce and dark red meranti have been systematically compared. The degree of coating penetration is mainly determined by the ability of the coating to flow into wood capillaries. Binder type, pigmentation, solid matter content and drying speed appeared to influence this ability. In softwoods the following different coating penetration routes are observed: the flow into open ends of longitudinal early- and latewood tracheids, the flow into ray cells and the transport from rays through the cross-field into longitudinal tracheids adjacent to rays. The possibility for the coating to follow the latter route is strongly influenced by the existing type of cross field pitting and to a lesser degree by the pigmentation of the paint. Clear differences between pine and spruce have been found with respect to the flow into ray parenchym and ray tracheids. The flow into open ends of longitudinal tracheids is strongly influenced by the grain angle of tracheids. Penetration into dark red meranti is mainly limited to vessels and rays. Tylose membranes can prevent the complete filling of vessels. The impact on penetration of the removal of extractives and of sanding of the surface has also been studied but appears to be of only minor importance.
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  • 6
    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
    Description / Table of Contents: Alle diese Reaktionen laufen innerhalb der ersten Stufe ab. Auch eine weitere Kondensation des Lignins über abgespaltene, positiv geladene Benzyl-Bruchstücke (Cα) und Methylenbrücken findet wahrscheinlich innerhalb der ersten Phase statt. Ebenso der Anstieg von reaktiven Seitengruppen der aromatischen Ringe einiger Lignineinheiten beginnt in dieser ersten Stufen und setzt sich in der nächsten fort. In der zweiten Behandlungsstufe setzt sich, wie die Autoren annehmen, die Autokondensation des Lignins über Methylenbrücken fort, wobei Seitengruppen der Benzolkerne durch Demethoxylierung abgespalten werden und positiv geladene Benzyleinheiten (Cα) entstehen. Einige der in der ersten Phase freihesetzten Aldehyde vernetzen die aromatischen Ringe des Lignins weiter über Methylenbrücken. Das Ausmaß dieser Reaktionen ist gering, führt aber dennoch zu einer Zunahme der Quervernetzung und infolge davon zu verbesserter Dimensionsstabilität und verringerter hygroskopischer Eigenschaft des Holzes.
    Notes: In the second treatment step completion of the autocondensation of lignin is believed to occur through the formation of methylene bridges connecting aromatic rings. The aromatic nuclei sites are released by demethoxylation and through the cleaved, positively charged benzylic Cα. Reactions of some of the aldehyde groups formed in the first step phase occur with lignin aromatic nuclei sites to connect aromatic rings through methylene bridges. The extent of these reactions is mild, but nonetheless they lead to an increase in cross-linking with consequent improvement in dimensional stability and decreased hygroscopicity of wood.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Holz als Roh- und Werkstoff 57 (1999), S. 215-221 
    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
    Description / Table of Contents: Metasequoia glyptostroboides , die zunächst als fossiles Holz bekannt war, wurde 1940 in Südost-China als lebender Baum entdeckt. Die ersten Samen wurden 1948 in die Niederlande gebracht, erste Anpflanzungen erfolgten 1957. Die Untersuchung dieser Species begann um 1960 mit dem Ziel, sie also Alternative für die forstliche Nutzung zu verwenden. Eine Übersicht über die ersten Ergebnisse erschien 1967. Untersuchungen über Wachstum and Habitus wurden 1992 durchgefüht. In der vorliegenden Arbeit wurden anatomische und physikalisch-mechanische Eigenschaften und die Dauerhaftigkeit des Holzes untersucht. Insgesamt wurden 23 Bäume von zwei verschiedenen Standorten ausgewählt. Die Ergebnisse wurden mit Daten von Metasequoia aus anderen Ländern und mit Eigenschaften anderer Nadelhölzer verglichen. Die mittlere Faserlänge war größer als bei britischen, aber kürzer als bei chinesischen Bäumen. Festigkeitseigenschaften und Dichte lagen niedriger im Vergleich zu Messungen an Metasequoia aus anderen Ländern und an anderen Nadelhölzern. Tangentiale Quellen und Schwinden war relativ hoch. Bei den chemischen Komponenten ist der Unterschied im Extraktgehalt besonders auffällig. Die Dauerhaftigkeit war größer also die von Kiefer und Douglasie. Zur Zeit findet das Schnittholz aus der jungen Metasequoia-Plantage in den Niederlanden kaum kommerzielles Interesse. In Anbetracht des Wachstums sowie unter guter waldbaulicher Bedingung könnte dieses Holz künftig eine Rolle bei Nadelholzplantagen spielen.
    Notes: Metasequoia glyptostroboides previously known from fossil material was discovered as a living tree in the early 1940s in southeast China. The first seeds were received in 1948 in the Netherlands and the first plants were planted in 1957. The research on this species started in the beginning of the 1960s. The aim of the research was to investigate its possible use in forestry as a good alternative for other species. In 1967 an overview of the first experiences on Metasequoia glyptostroboides in the Netherlands was given. Research on the growth and habitus of the different clonals was done in 1992. In this study, the wood was examined regarding anatomical characteristics, physical-mechanical and chemical properties as well as durability. A total of 23 trees from two different stands was selected for this purpose. The data of the different properties were compared with those of Metasequoia glyptostroboides grown in other countries and other commercial softwood species. The average fibre length proved to be longer than the British data but shorter than the fibres measured on a specimen of Metasequoia from China. Strength properties and density gave lower values compared to data of Metasequoia from other countries and commercial species. The tangential swelling and shrinkage was relatively high. With respect to the chemical composition, the difference in the extractive substances of heartwood and sapwood was remarkable. The durability tests showed higher durability for Metasequoia heartwood than for Scots pine and Douglas fir. Presently, timber of the young plantation-grown Metasequoia is not of high commercial interest in the Netherlands. However, considering its production and good silvicultural treatment, the species might be of interest as a source of plantation grown softwood.
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  • 8
    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
    Description / Table of Contents: −11  m s−2, abhängig von der Oberflächenbehandlung. Diese Diffusionsmaße waren allerdings nicht geeignet, um das Holzfeuchte-Profil zu bestimmen, das einen starken Anstieg der Feuchte nahe der Oberfläche zeigte. Die genaueste Bestimmung des Holzfeuchte-Profils ergab sich durch Einbeziehung der wechselnden Oberflächenkonzentration und des Diffusionskoeffizienten von Sorptionsdaten unbehandelten Holzes. Allgemein scheint Diffusion der wichtigste Faktor für den Transport von flüssigem Wasser zu sein. Kapillarer Transport von Wasser beeinflußt die Sorption nur nahe der Oberfläche. Dieser Aspekt ist bedeutsamer für unbeschichtetes Holz.
    Notes: −11  m s−2 depending on the surface treatment. These diffusivities were however, not suitable to predict the moisture content profiles in the coated wood, which showed a strong increase close to the surface. The most accurate prediction of the moisture content profile was based on the changing surface concentration and the diffusion coefficient from sorption data of uncoated wood. In general, diffusion seemed to be the most important factor in the transport of water. Capillary flow of water only influenced the sorption very close to the surface of the wood. This aspect became more important for uncoated wood.
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  • 9
    Publication Date: 1993-09-01
    Print ISSN: 0018-3768
    Electronic ISSN: 1436-736X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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  • 10
    Publication Date: 2002-12-01
    Print ISSN: 0018-3768
    Electronic ISSN: 1436-736X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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