Sekundäre Veränderungen im Holz akut belasteter Fichten (Picea abies [L.] Karst.) in Hochlagen des Osterzgebirges

Koch, Gerald; Bauch, J.; Dünisch, Oliver; Seehann, G.; Schmitt, Uwe

doi:10.1007/s001070050175

Cited by 15 publications

(2 citation statements)

References 16 publications

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“…Such a predisposition has been discu ssed as the likely cause of 'brash' fractures of wood under impact stress, e.g . in living spruce trees (Delorme 1974;Delorme & Verhoff 1975;Koch et al 1996). Conclusive evidence for such slip planes was found only near the fracture lines (tension zone) of the 'brash' specimens at TEM level (Fig.…”

Section: Resultsmentioning

confidence: 98%

Fracture Morphology of Hickory (Carya Spp., Juglandaceae) Under Single-Blow Impact Loading

Schmitt¹,

Richter²,

Wittke³

1996

IAWA J

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Wood specimens of the true hickory group were tested for their shock resistance with the single blow impact method. From this test series 10 pieces with a uniform fracture mode, 'brash' and 'tough' , were selected for electron microscopy to examine the fracture mode of individual fibres in the tensile zone. 'Brash' specimens are characterized by well defined transverse or slightly oblique fracture lines across the entire cell wall, or a stepped-up course preferably within the secondary wall. Stepping-up mainly occurs along the interface between S1 and S2 layer or between primary wall and S1 layer. The smooth fracture of fibres in 'brash' specimens appears to be caused by compression-induced pre-slip planes which do not occur in 'tough' specimens. Individual fibres of 'tough' specimens mostly display a conspicuous and irregular zigzag course of the fracture line due to the tearing apart of fibrillar bundles . In addition, 'tough' specimens are characterised by the regular development of microcracks at a distance of up to several millimeters from the fracture plane. Such microcracks were not observed in 'brash' specimens. The described micro morphological differences between both fracture modes help to explain the considerable variation in shock resistance between specimens of similar density and gross wood structure.

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Section: Resultsmentioning

confidence: 98%

Fracture Morphology of Hickory (Carya Spp., Juglandaceae) Under Single-Blow Impact Loading

Schmitt¹,

Richter²,

Wittke³

1996

IAWA J

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“…The respective absorbance curves 1 and 2 exhibited a maximum at about 280 nm wavelength and a decrease to 260 nm, features frequently taken as an indicator for lignin in the cell wall (Fergus et al 1969). This type of spectra can also be used for qualitative and quantitative lignin characterization (Bauch et al 1976;Koch et al 1996).…”

Section: Uv-microspectrophotometrymentioning

confidence: 97%

Wood Decay by the White-Rotting Basidiomycete Physisporinus vitreus from a Cooling Tower

Schmidt¹,

Schmitt²,

Moreth³

et al. 1997

HFSG

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KeywordsBasidiomycetes in cooling towers Physisporinus vitreus Decay of water-saturated specimens Micromorphology Manganese deposits Lignin degradation SummaryTimbers in cooling towers are mainly attacked by soft rot causing fungi which belong to Ascomycetes and Deuteromycetes. The basidiomycete Physisporinus vitreus degraded water-saturated timber as fibrous white-pocket rot in a cooling tower in which water treatment had been changed from chlorine to ozone. In the laboratory, the fungus revealed a remarkable wood decay pattern. In crosswise piled, water-saturated pine specimens it attacked only those parts not surrounded by air. The decay occurred as small longish delignified white pockets, preferentially in the earlywood. Transmission electron microscopy of unstained sections showed some electron density in the hyphal extracellular layer and in the wood cell wall beneath a hypha. Contrasted with KMnO 4 staining, these regions became more pronounced which may indicate presence of lignin degradation products. UV-microspectrophotometry of these areas exhibited an increased absorbance. Many decay pockets were black due to manganese (Mn) deposits. Mn determination by inductively coupled plasma emission (ICP) revealed up to 518ppm Mn. TEM/EDXA showed Mn deposits in the hyphal extracellular layer, on the cell wall surface and in the inner S 2 layer beneath a hypha. The Mn may be related to the lignin attacking peroxidases.

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What Are Natural Fibres?

Akin¹,

Eder²,

Burgert

et al. 2010

Industrial Applications of Natural Fibres

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Sekundäre Veränderungen im Holz akut belasteter Fichten (Picea abies [L.] Karst.) in Hochlagen des Osterzgebirges

Cited by 15 publications

References 16 publications

Fracture Morphology of Hickory (Carya Spp., Juglandaceae) Under Single-Blow Impact Loading

Fracture Morphology of Hickory (Carya Spp., Juglandaceae) Under Single-Blow Impact Loading

Wood Decay by the White-Rotting Basidiomycete Physisporinus vitreus from a Cooling Tower

What Are Natural Fibres?

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