D. Fengel’s research while affiliated with University Hospital München and other places

... Wood material darkens upon heat treatment, where the degree of color change depends on the duration and the temperature of the thermal modification. During the thermal modification of wood material, enzyme-mediated reactions occur between sugars, phenolic compounds, and amino acids (Fengel and Wegener 1983;Saka 1993;Montero et al. 2012). This enzyme-mediated reaction of wood material can cause hydrolysis and oxidation of components, thus changing the color of the wood (Bekhta and Niemz 2003;Lamason and Gong 2007;Chen et al. 2020;Ulker et al. 2012;Mitani et al. 2013). ...

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Properties of Thermally Modified Scots Pine (Pinus sylvestris L.), Kazdağı Fir (Abies equi-trojani Asch. et Sint.), and Eastern Beech (Fagus orientalis Lipsky)

... However, larch wood and pine heartwood are less durable than oak and sweet chestnut, and neither of the former retained their hydrophobic nature after various types of aging (Tables 5 and 6). This result might explain the lower durability of these two materials, despite their fairly high extractive contents (Fengel and Wegener 1989). ...

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Influence of Artificial and Natural Weathering on the Hydrophobicity and Surface Properties of Wood

... The recovered lignin was collected by centrifugation, washed several times with distilled water to remove residual sulfuric acid, and freeze-dried. The yields of the recovered lignin fractions (%) were determined with respect to the initial lignin content in beech wood (24.4%) 37 and in spruce (28.5%). 38 Compositional cellulose-rich pulp analysis to determine cellulose, xylan, and lignin was performed using methods described in NREL TP:510-42618. ...

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Design of Organosolv Lignin Fractionation: Influence of Temperature, Antisolvent, and Source on Molecular Weight, Structure, and Functionality of Lignin Fragments

... Highly toxic synthetic wood preservatives, such as chromated copper arsenate (CCA) or creosote, can be partially replaced with nontoxic extractives. 5 The overall content of extractives varies greatly between tree species and tissues, ranging from 21% for Picea abies L. Karst., 6 of which roughly 5% is extracted by nonpolar solvents as dichloromethane (DCM) or petroleum ether, 7,8 to 40% for Schinopsis lorentzii Engl. based on the dry mass of wood or bark. ...

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Tools for Bark Biorefineries: Studies toward Improved Characterization of Lipophilic Lignocellulosic Extractives by Combining Supercritical Fluid and Gas Chromatography

... These bonds confer significant resistance against degradation (Carlile et al., 2015). On the other hand, the biological degradation susceptibility of conifer wood fiber can be especially attributed to the high decomposing vulnerability of cellulose and hemicellulose (Fengel and Wegener, 1989). In the present study, the observed change in hemicellulose (and to lesser extent lignin) percentage in wood fiber (Figure 1) is likely related to the proportional decrease in percentage of cellulose which led to an overall increase of percentage share of other constituents. ...

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Reuse of coir, peat, and wood fiber in strawberry production

... In contrast to cellulose, they are branched polymers of lower molecular weight and consist of various sugar units apart from -glucose. These units can be divided into pentoses, such as -D-xylose and ↵-L-arabinose, hexoses, including -D-mannose and ↵-D-galactose, as well as hexuronic acids and deoxy-hexoses [69]. The main chain (backbone) of hemicelluloses consists of either one unit, for instance xylose in xylan, or of two or more units as mannose and glucose in glucomannans, which are linked -(1!4). ...

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Impact of type and pretreatment of lignocellulosics on lignin and pulp properties

... In hemicelluloses, the main polymer chain is usually composed of L-arabinose (about 10 %), D-xylose (nearly 90 %) (Mussatto and Dragone, 2016). The principal component of hemicelluloses in hardwood and herbaceous plants such as grasses and straw are xylans while in softwood it is glucomannan (Fengel and Wegener, 1983). A report suggests that hemicelluloses are linked to other hemicelluloses through covalent and hydrogen bonds, to lignin via cinnamate acid ester linkages or covalent linkages, and cellulose microfibril through intermolecular hydrogen bonding and Van der Waals forces (Sjostrom, 1993;Xu, 2010) ...

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Enzyme mediated multi-product process: A concept of bio-based refinery

... In addition, the lowest level of hot-water-soluble extractives was observed near the heartwood. This pattern is in agreement that substances soluble in water such as starch and pectin are more abundant in the sapwood near the bark than in the heartwood (Fengel and Wegener 1984). The highest average value of total phenolic content was found near the pith (152.19 ...

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Chemical components of boiling-treated sengon (Paraserianthes falcataria (L.) I. C. Nielsen) wood

... In subsequent observations of the infested pupae, any influence of the vital staining on the vitality of the pupa has to be considered. Furthermore, trypan blue as a toxic compound (Falbe and Regitz, 1995) could affect the survival of the bee. Since integumental perforations normally scar towards the end of the pupal phase (Kanbar and Engels, 2003), we also wanted to know whether this healing process is influenced by a preceding staining procedure. ...

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Survival of honey bee (Apis mellifera) pupae after trypan blue staining of wounds caused by Varroa destructor mites or artificial perforation

... In accordance with this, most of the references report an increase in proportional lignin content [14,28,33,48]. However, degradation of the lignin, caused by oxidation processes [5,14,15], was also observed [16,43]. Cellulose is the most resistant constituent of wood, found to be almost intact even in samples aged up to 4,000 years [6,13,14]. ...

Reference:

Determination of Dynamic Elastic Moduli and Shear Moduli of Aged Wood by Means of Ultrasonic Devices