1,721,007 research outputs found
Univariate and Multivariate Analysis of Tannin-Impregnated Wood Species Using Vibrational Spectroscopy
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Calorific Value and Ash Content of Extracted Birch Bark
Full text linkWood bark is one of the main residues in the forest industry worldwide. Currently, the
bark is used to produce process heat and energy. A major amount of this is mainly used in power and
heating plants. Due to the fact that the demand for heating energy is seasonal, the storage of bark is
necessary. The storage process of bark and therefore related problems (like biomass loss, increase of
ash content etc.) were discussed in previous studies. Different approaches to increase the economic
and ecologic value of wood bark through gaining extractives from the bark were investigated in order
to revalue this by-product as well. This study shows the change in calorific value and ash content of
birch bark based on results of ultrasound-assisted extraction (UAE). Regarding the energy content
(gross calorific value), a comparison was made that showed that due to the extraction process, the
energy content of the birch bark is decreased. The extraction yield of the methanol extracts results as
17.74%. The total phenolic content (TPC) of this extract was 447.75 mg GAE/g of oven-dried bark
extracts. The amount of ash increased by 23.74% after the extraction. The gross calorific value of the
birch bark decreased by 6.98%. The calculated energy content decreased from 2.48 MWh/m3 before
extraction to 1.61 MWh/m3 after extraction, which is a loss of 35.08%. The obtained results show
that through the extraction of birch bark via ultrasound-assisted extraction, valuable substances can
be produced. At the same time, the ash content of extracted birch bark increased whereas the energy
content decreased
Surface properties of tannin-treated wood during Natural and Artificial Weathering
No full textTannins are the natural substances that plants use to protect wood. Novel tannin based formulations were tested to evaluate their efficacy in preventing weathering degradation of the surfaces. Scots pine and European beech specimens were treated with flavonoid based wood preservatives and exposed to artificial and natural weathering. The surface properties of the samples before and after weathering were evaluated using contact angle and colour measurements. Tannin treated samples showed a moderate resistance against discoloration and greater wettability than untreated samples. ATR-FT-MIR and FT-NIR spectroscopies combined with principal component analysis (PCA) revealed that weathering mainly degrades the aromatic component of wood. Because the protective tannin network is nothing more than an aromatic polymer, it suffers a similar degradation of lignin. Although the higher amount of aromatics leads to higher degradations, it is still possible to observe via vibrational spectroscopies ..
Reduction of the surface colour variability of thermally modified Eucalyptus globulus wood by colour pre-grading and homogeneity thermal treatment
No full textA new method that consists of combining wood pre-grading by surface colour followed by the application of homogeneity
thermal treatments is proposed to reduce the surface colour variability of the thermally modified blue gum wood. To identify
the conditions of the homogeneity thermal treatment for two pre-graded groups with different initial surface colours (pinkish
and yellowish), the effects of applying 25 different thermal treatment intensities to such groups were analysed. The effects
of this method on mass loss and volumetric swelling were also analysed. Results show that an optical pre-grading of the
wood samples and treatments under different conditions can reduce the colour variability of the blue gum wood samples, as
well as the volumetric swelling. Mass loss was not homogenised after the treatment, but the difference of masses between
the two groups was similar to their untreated state. The application of this new methodology may be of interest for the sawn
timber industry to bring more uniform boards on the markets and to promote Eucalyptus globulus as a price-competitive
and sustainable alternative timber
Starch-sugar synergy in wood adhesion science: basic studies and particleboard production
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