Published by De Gruyter

Volume 74 Issue 1

Issue of Holzforschung

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Contents
Journal Overview

Original Articles

July 26, 2019

Genotypic variation in the basic density, dynamic modulus of elasticity and tracheid traits of Pinus elliottii in three progeny trials in southern China

Meng Lai, Leiming Dong, Chunhui Leng, Lu Zhang, Min Yi

Page range: 1-9

Abstract

A firm understanding of the genetic relationships among wood properties is a prerequisite for breeding for higher wood quality in Pinus elliottii families. To examine and deal with such relationships, increment cores were sampled at breast height from 1260 trees in 42 open-pollinated families in three 27-year-old Slash pine progeny trials in southern China, and genetic variation, genotype-by-environment (G × E) interaction, genetic correlation and correlated response were investigated. The basic density (BD), dynamic modulus of elasticity (MOE D ) and tracheid traits were found to be under moderate to strong genetic control for the three locations combined, with individual narrow-sense and family mean heritability ranging from 0.28 to 0.44 and 0.52 to 0.69, respectively. Type B genetic correlation estimates indicated that the G × E interaction had a small-level influence on wood properties. Strong genetic correlations (r g ) were found between BD and MOE D at the three sites (r g = 0.46–0.85), and BD or MOE D showed moderate to strong correlations with most tracheid traits at specific localities. In tree breeding programs, one possible strategy would be to improve pulpwood quality and the strength of structural wood through selection for different wood quality traits.

August 14, 2019

Moisture-dependent orthotropic viscoelastic properties of Chinese fir wood during quenching in the temperature range of 20 to −120°C

Zhu Li, Jiali Jiang, Jianxiong Lyu

Page range: 10-19

Abstract

An understanding of wood’s moisture-dependent viscoelastic properties under various temperature conditions is important for assessing its utilization and product quality. In this study, we investigated the influence of moisture content (MC) on the orthotropic viscoelasticity of Chinese fir wood ( Cunninghamia lanceolata [Lamb.] Hook.) during quenching ranging from 20 to −120°C. The storage modulus ( E ′) and loss factor (tan δ ) of the longitudinal (L), radial (R) and tangential (T) specimens were determined for nine MC levels ranging from 0.6 to 60.0%. The results showed that E ′ generally decreased with increasing amount of bound water in all orthotropic directions, regardless of the temperature. In contrast, a sharp increase in E ′ was observed at temperatures below 0°C when free water was present, due to the formation of ice within the cell lumens. The γ-relaxation and β-relaxation were observed in the temperature spectrum. A comparison demonstrates that the β-relaxation showed evident grain orientation. When only bound water was present in the wood cell wall, one clear γ-relaxation was found for all orthotropic directions. In contrast, only the high-temperature side of the γ-relaxation was observed in the three anatomic directions in specimens with free water, which might be related to the amorphous wood cell wall coupling with the frozen free water during the quenching process. In addition, the differences in peak temperatures of the γ-relaxation among the three main directions diminished with increasing bound water.

Publicly Available August 15, 2019

Comparison of whole-tree wood property maps based on near-infrared spectroscopic calibrations utilizing data at different spatial resolutions

Laurence R. Schimleck, Finto Antony, Christian Mora, Joseph Dahlen

Page range: 20-32

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Abstract

Near-infrared (NIR) spectra or NIR-hyperspectral images obtained from radial strips or wood discs provide a cost-effective methodology for examining wood property variation within trees. The calibration used for wood property prediction is critical and can be obtained using two fundamentally different approaches. One involves using a spatial-specific model where wood property data and corresponding spectral data are measured at the same resolution for calibration and prediction, e.g. 10-mm radial increments. The other provides a spatial-interpolated model and involves measuring a property on a broad-scale, e.g. whole-tree, calibrating this data against NIR spectra representing the equivalent scale and then using the calibration to predict the property at higher resolution. To understand the impact of these approaches on subsequent patterns of within-tree variation, whole-tree air-dry density (ADD) and coarseness maps, based on data obtained using the two different approaches, were compared. Patterns of ADD and coarseness variation were comparable indicating that both approaches can be utilized to examine within-tree variation. Spatial-interpolated models have a distinct advantage; being based on whole-tree (or disc) samples, they greatly reduce the cost of wood property analysis and allow the development of maps for properties that are costly and difficult to measure, for example, pulp yield.

Open Access September 10, 2019

Variation and serial correlation of modulus of elasticity between and within European oak boards (Quercus robur and Q. petraea)

Cristóbal Tapia, Simon Aicher

Page range: 33-46

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Abstract

This research aimed at describing the tensile modulus of elasticity (MOE), density and knot variability between and within oak ( Quercus robur , Q. petraea ) boards, which is essential for the stochastic modeling of wooden composites, such as glulam. Longitudinal deformations for 100-mm long cells were measured. The local density variation along boards revealed a very low mean coefficient of variation (COV) of 3%. The global MOE was precisely predicted from local (cell) MOEs, which span from 2.6 to 22 GPa. The mean COV of local MOE along board length was 12%, with extremes of 3% and 28%. The cell-related relationships of MOE with either density or knot area ratio showed low R -values of 0.4 and 0.3, respectively. A multivariate linear regression with both variables increased the MOE prediction to R = 0.6, which is below the literature results for beech and spruce wood. A serial correlation analysis of the local MOE was performed for board segments quasi-free of knots and for all cells, investigating different normalization approaches. Applying no MOE normalization delivered too high correlations due to pronounced inter-board MOE variations. A normalization based on an averaged maximum MOE per board delivered reasonable serial correlation results for the first four lags of the MOE knot-free variation (0.61; 0.38; 0.19 and 0.08). Considering also the knot-affected cells reduced the serial correlation roughly by a factor of 2.

Open Access August 14, 2019

Natural durability of subfossil oak: wood chemical composition changes through the ages

Jan Baar, Zuzana Paschová, Tamás Hofmann, Tomáš Kolář, Gerald Koch, Bodo Saake, Peter Rademacher

Page range: 47-59

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Abstract

In recent years, subfossil oak has become increasingly popular, particularly in the manufacture of small wooden products. Due to the long period of its underground preservation, detailed knowledge of its properties is essential to properly use this material. In this study, subfossil oak samples dated to approximately 1000, 2000 and 3000 years BP and recent oak samples were chemically analyzed to determine the contents of extractives, the main wood components, and inorganic elements. The results were then evaluated in light of their natural durability. The mass loss of subfossil oak was 2–3 times lower than that of the recent sample, but the age of the subfossil oak itself had no influence on its durability. The long-term leaching process of water-soluble ellagitannins, together with their hydrolysis and bonding in ferric tannate complexes, were responsible for the decreased durability. The oldest subfossil oak had the lowest amount of phenolic compounds and the highest content of inorganic elements. Optical emission spectrometry proved an increase in inorganic elements 5–7 times higher than recent oak content, with the highest increase found for calcium and iron. Compared to recent oaks, subfossil oaks manifested decreased content of carbohydrates and correspondingly increased lignin content. Our results revealed that subfossil oak cannot be considered a suitable material for exterior use under aerobic conditions.

July 31, 2019

Thermo-vacuum treatment of poplar (Populus spp.) plywood

Roberto Zanuttini, Gaetano Castro, Corrado Cremonini, Francesco Negro, Sabrina Palanti

Page range: 60-67

Abstract

Poplar cultivation is enduring a long-lasting crisis in Italy, but it is still playing a relevant role in the Italian and European wood sectors. To improve its prospects, the manufacturers of poplar plywood have recently activated various strategies to make it a distinguished panel with specific performances. In this frame, thermo-treatment could open new applications and markets. The present study investigates the physico-mechanical properties of thermo-treated poplar plywood. For this purpose, panels were manufactured with urea-melamine-formaldehyde adhesive, both in a standard mixture and added with resorcinol. They were then treated by the Termovuoto ® process at 170, 190 and 210°C for 2 h. Changes in density, bonding quality, bending strength, modulus of elasticity, color and durability related to the aforementioned temperatures were investigated. Overall, the bonding quality of treated panels complied with the requirements of EN 314-1 and 2; bending strength and modulus of elasticity decreased, color darkened and durability increased. The latter is particularly important, because poplar wood is not durable and this process makes it suitable for use in humid conditions, offering new prospects for poplar plywood applications.

July 25, 2019

Dynamic moisture sorption and dimensional stability of furfurylated wood with low lignin content

Tiantian Yang, Erni Ma, Jinzhen Cao

Page range: 68-76

Abstract

Degradation of lignin occurs naturally in wood due to the influence of microorganisms or photic radiation. To improve the properties of wood with low lignin content, furfuryl alcohol (FA) at the concentration of 25% was used to modify poplar wood ( Populus euramericana Cv.) after partial delignification. Moisture sorption and dimensional stability of the samples were investigated under dynamic conditions where the relative humidity (RH) was changed sinusoidally between 45% and 75% at 25°C. Both the moisture content (MC) and the tangential dimensional change varied with a sinusoidal shape similar to the RH. Hygroscopicity and hygroexpansion increased after delignification, while furfurylation led to an inverse impact by reducing MC, dimensional changes, amplitudes of MC and dimensional changes, moisture sorption coefficient (MSC), and humidity expansion coefficient (HEC). After delignification and further furfurylation, the MC and the dimensional changes were reduced by about 20%, and the maximum drop in amplitudes of MC and dimensional changes was about 30%, while the MSC and the HEC decreased by over 15%. In addition, the furfurylated wood with low lignin content exhibited lower sorption hysteresis and swelling hysteresis.

August 17, 2019

From hollow lignin microsphere preparation to simultaneous preparation of urea encapsulation for controlled release using industrial kraft lignin via slow and exhaustive acetone-water evaporation

Miao Wang, Yadong Zhao, Jiebing Li

Page range: 77-87

Abstract

Lignin nano/microparticles have recently attracted growing interest for various value-additive applications of lignin, especially encapsulation. In this study, in order to establish a highly efficient and highly productive preparation process to effectively utilize technical lignin, a brand-new, slow and exhaustive solution evaporation process following a simple, self-assembly principle was developed using industrial softwood kraft lignin (SKL) from a starting acetone-water (80/20, v/v) solution to recover 100% of the lignin as homogeneous and well-shaped microspheres. The prepared microspheres had a typical average diameter of 0.81 ± 0.15 μm and were hollow with very thin shells (of nanoscale thickness). Based on this developed technique, encapsulation of urea by these lignin microspheres was directly achieved using the same process as hollow lignin microspheres with urea attached to the outside and entrapped inside of the wall. Two distinct urea release rates were observed for the urea-encapsulated microspheres: a fast release of the urea outside the shell wall and a slow (controlled) release of the urea inside the shell wall. The encapsulation efficiency was as high as 46% of the trapped urea as encapsulated inside the lignin microspheres. The slow and exhaustive solution evaporation procedure reported here is a simple and straightforward method for the valorization of industrial kraft lignin as hollow microspheres with controllable, homogeneous and desired morphologies, and especially for the direct preparation of lignin-based encapsulating fertilizers for controlled release.

Short Note

August 21, 2019

Lignan glycosides from the stems of Viburnum melanocarpum and their α-glucosidase inhibitory activity

Chunchao Zhao, Jia Chen, Jianhua Shao, Jie Shen, Wenyan Gu, Xiaohui Zhang, Yusi Sha

Page range: 88-93

Abstract

Two new lignan glycosides ( 1 , 2 ) and four known lignan glycosides ( 3 – 6 ) have been isolated from the ethanolic extract of the stems of Viburnum melanocarpum through repeated column chromatography. Their structures including absolute configurations were confirmed by spectroscopic data [one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass spectra (HRESIMS), optical rotatory dispersion (ORD) and circular dichroism (CD)] and chemical methods. Additionally, the α -glucosidase inhibitory activity of these compounds was tested in vitro . Compound 1 exhibited the strongest inhibitory activity against α -glucosidase with a half-maximal inhibitory concentration (IC 50 ) value of 10.3 μM.

About this journal

Objective
Holzforschung (HF) is an international scholarly journal that publishes cutting-edge research on the biology, chemistry, physics and technology of wood and wood components. High quality papers about biotechnology and tree genetics are also welcome. Rated year after year as one of the top scientific journals in the category of Pulp and Paper (ISI Journal Citation Index), Holzforschung represents innovative, high quality basic and applied research. The German title reflects the journal's origins in a long scientific tradition, but all articles are published in English to stimulate and promote cooperation between experts all over the world. Ahead-of-print publishing ensures fastest possible knowledge transfer.

Topics

Biology, chemistry, physics and technology of wood and wood components
Biotechnology and tree genetics

Article formats
Original articles, Reviews, Short notes

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