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3区 农林科学 Q2 FORESTRY Pub Date : 2023-05-01 DOI: 10.1515/hf-2023-frontmatter5
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引用次数: 0
Role of α-Fe2O3 nano-particles in protecting wood from ultraviolet light degradation α-Fe2O3纳米颗粒对木材抗紫外线降解的保护作用
IF 2.4 3区 农林科学 Q2 FORESTRY Pub Date : 2023-04-27 DOI: 10.1515/hf-2023-0001
Tengfei Yi, J. Morrell
Abstract The incorporation of nano-particles into coatings to protect wood against UV light has tremendous potential for improving coating performance. However, the understanding of the mechanisms by which these particles function on wood surfaces remains limited. The distribution and potential chemical interactions between alpha Fe2O3 and wood were studied. The ability of different sizes of Fe2O3 particles to intercept various wavelengths of light was assessed using ultraviolet/visible (UV–vis) spectroscopy using TiO2 and ZnO particles for comparison. All particles intercepted UV light, but α-Fe2O3 also intercepted a portion of the visible spectrum which might help explain its better performance. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS) analysis of α-Fe2O3 nano-particle distribution on different wood orientations of radiata pine (Pinus radiata D. Don) and shining gum (Eucalyptus nitens) showed that iron particles were uniformly distributed on both pine and shining gum, but provided better UV protection to the more permeable radiata pine surfaces. Characterization of chemical interactions between α-Fe2O3 and isolated lignin and cellulose by Fourier Transform Infrared Spectroscopy (FTIR) suggested substantial interactions between these particles and lignin components, but little interaction with cellulose. The results suggest that the role of nano-particles in the UV protection of wood surface is to intercept and disperse the light energy while interacting with the wood.
摘要将纳米粒子掺入涂层中以保护木材免受紫外线照射,对提高涂层性能具有巨大潜力。然而,对这些颗粒在木材表面发挥作用的机制的理解仍然有限。研究了α-Fe2O3与木材之间的分布和潜在的化学相互作用。使用紫外线/可见光(UV–vis)光谱评估不同尺寸的Fe2O3颗粒拦截不同波长光的能力,并使用TiO2和ZnO颗粒进行比较。所有粒子都拦截了紫外线,但α-Fe2O3也拦截了一部分可见光谱,这可能有助于解释其更好的性能。扫描电子显微镜/能量色散X射线光谱(SEM-EDS)分析了α-Fe2O3纳米粒子在辐射松(Pinus radiata D.Don)和闪胶(Eucalyptus nitens)不同木材取向上的分布,结果表明,铁粒子均匀分布在松和闪胶上,但对渗透性更强的辐射松表面提供了更好的紫外线防护。通过傅立叶变换红外光谱(FTIR)表征α-Fe2O3与分离的木质素和纤维素之间的化学相互作用,表明这些颗粒与木质素组分之间存在大量相互作用,但与纤维素的相互作用很少。结果表明,纳米粒子在木材表面紫外线防护中的作用是在与木材相互作用时拦截和分散光能。
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引用次数: 0
Synergistic improvement to dimensional stability of Populus cathay ana via hemicellulose removal/alkali lignin impregnation 半纤维素去除/碱木质素浸渍协同提高杨的尺寸稳定性
IF 2.4 3区 农林科学 Q2 FORESTRY Pub Date : 2023-04-24 DOI: 10.1515/hf-2022-0147
Meng Yang, Runhua Zhang, E. Ma
Abstract Poor dimensional stability restricts the commercial utilization of fast-growing wood. In this study, fast-growing poplar (Populus cathayana) was treated by removing hemicellulose with hydrothermal treatment and impregnating alkali lignin via full-cell process, synergistically, for enhanced dimensional stability. After modification, hydroxyl groups were reduced in hemicellulose removed wood (DHC), alkali lignin was observed to fill in the cell lumens of vessels and wood fibers in the impregnated wood (AL) and in the wood modified by hemicellulose removal with alkali lignin impregnation (DHCAL). Compared with untreated wood, the volumetric swelling ratio of DHC and AL decreased by 11 % and 21 % under relative humidity (RH) of 89 %, respectively. The volumetric swelling ratio of DHCAL decreased by over 50 %, indicating a positive synergistic effect. The combination of hemicellulose removal and alkali lignin impregnation treatment improved the dimensional stability of wood significantly by reconstructing wood chemical components with various levels of hygroscopicity. This work could meaningfully contribute to the efficient utilization of fast-growing wood and promote the added value of industrial alkali lignin.
尺寸稳定性差限制了速生木材的商业利用。本研究以速生杨(Populus cathayana)为材料,采用水热处理去除半纤维素和全细胞浸渍碱木质素的方法进行处理,协同提高杨的尺寸稳定性。改性后,半纤维素去除木材(DHC)中的羟基减少,在浸渍木材(AL)和用碱木质素浸渍半纤维素去除改性的木材(DHCAL)中,观察到碱木质素填充在容器和木材纤维的细胞腔中。与未处理的木材相比,DHC和AL的体积膨胀比降低了11 % 和21 % 相对湿度(RH)为89 %, 分别地DHCAL的体积膨胀率降低了50以上 %, 表明了积极的协同作用。半纤维素去除和碱木质素浸渍处理相结合,通过重建具有不同吸湿性水平的木材化学成分,显著提高了木材的尺寸稳定性。这项工作有助于速生木材的有效利用,提高工业碱木质素的附加值。
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引用次数: 0
Structural comparison of different isolated eucalyptus lignins and analysis of their interaction mechanism with bovine serum albumin solution under QCM-D 不同分离桉树木质素的结构比较及其与牛血清白蛋白溶液相互作用机制的QCM-D分析
IF 2.4 3区 农林科学 Q2 FORESTRY Pub Date : 2023-04-17 DOI: 10.1515/hf-2022-0170
Haonan Zhang, Qi Liu, Yanchen Zhu, Zhang Feng, Hao Ren, H. Zhai
Abstract In this study, representative lignin samples differing in hydroxyl content, molecular weight, linkage composition and lignin units ratio were prepared from eucalyptus wood by different isolation means and modification means: milled wood lignin (MWL), kraft lignin classified at different pH (KL), lignocresol (LC), lignoresorcinol (LR), lignopyrogallol (LP) as well as lignocresol secondary functional switched samples (LC 2ndderiv). The structure of various lignins was characterized in detail by Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR). In order to eliminate the interference of other factors, bovine serum albumin (BSA) with relatively simple protein structure and different kinds of lignin and their derivatives were selected as the research objects. The adsorption/desorption behavior and mechanism between lignin samples and BSA were studied by quartz crystal microbalance with dissipation monitoring (QCM-D). The results showed that the content of phenolic hydroxyl was the main factor affecting the interaction of lignin and BSA, but in addition, the molecular size, linkages composition and the types of lignin units also had important effects on its adsorption behavior. The research will provide theoretical guidance and all-round reliable basic data for the interaction of lignin on lignocellulose hydrolysis enzymes in industrial application.
摘要本研究以桉树为原料,采用不同的分离和改性方法制备了羟基含量、分子量、连接组成和木质素单元比不同的代表性木质素样品:磨木木质素(MWL)、不同pH下分类的硫酸盐木质素(KL)、木质甲酚(LC)、木质间苯二酚(LR),木质邻苯三酚(LP)以及木质甲酚二级功能切换样品(LC 2ndderiv)。通过傅立叶变换红外光谱、凝胶渗透色谱和核磁共振对各种木质素的结构进行了详细表征。为了消除其他因素的干扰,选择蛋白质结构相对简单的牛血清白蛋白(BSA)和不同种类的木质素及其衍生物作为研究对象。采用耗散监测石英晶体微天平(QCM-D)研究了木质素样品与BSA的吸附/解吸行为及其机理。结果表明,酚羟基含量是影响木质素与BSA相互作用的主要因素,但分子大小、键组成和木质素单元类型对其吸附行为也有重要影响。该研究将为木质素与木质纤维素水解酶的相互作用在工业应用中提供理论指导和全方位可靠的基础数据。
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引用次数: 0
Adding gaseous ammonia with heat treatment to improve the mechanical properties of spruce wood 热处理添加氨水改善云杉木材力学性能
IF 2.4 3区 农林科学 Q2 FORESTRY Pub Date : 2023-04-17 DOI: 10.1515/hf-2022-0179
Yiqin Gao, Li Li, Yao Chen
Abstract Degradation of the mechanical properties of heat-treated wood is a significant problem that needs to be addressed. This study aimed to stabilize the mechanical strength of heat-treated spruce wood by adding gaseous ammonia during the heat treatment. Gaseous ammonia penetrates rapidly into wood and is expected to form ammonium hydroxide when combined with water in the wood. This modification strategy neutralizes the acids produced by the degradation of hemicelluloses and reduces the degradation of the wood polymer composition and cell-wall structure. The preservation of wood polymer composition and cell-wall structure increases the indentation modulus of the wood cell walls. This increases the strength of the wood cell walls, resulting in an improvement in the mechanical properties of the heat-treated wood. The heat-treated wood’s dimensional stability and equilibrium moisture content are only slightly affected by the weak alkalinity modification.
摘要热处理木材力学性能的退化是一个需要解决的重大问题。本研究旨在通过在热处理过程中添加气态氨来稳定热处理云杉木材的机械强度。气态氨迅速渗透到木材中,当与木材中的水结合时,预计会形成氢氧化铵。这种改性策略中和了半纤维素降解产生的酸,并减少了木材聚合物组合物和细胞壁结构的降解。木材聚合物成分和细胞壁结构的保存增加了木材细胞壁的压痕模量。这增加了木材细胞壁的强度,从而改善了热处理木材的机械性能。弱碱性改性对热处理木材的尺寸稳定性和平衡含水量影响不大。
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引用次数: 0
Effects of seismic strain rates on the perpendicular-to-grain compression behaviour of Dahurian larch, Mongolian pine and Chinese poplar: tests and stress-strain model 地震应变速率对落叶松、蒙古松和白杨垂直颗粒压缩行为的影响:试验和应力-应变模型
IF 2.4 3区 农林科学 Q2 FORESTRY Pub Date : 2023-04-14 DOI: 10.1515/hf-2022-0135
Lipeng Zhang, Qifang Xie, Yajie Wu, Baozhuang Zhang, Ningfen Su
Abstract Wood is mainly subjected to transverse compression in many critical parts of Chinese traditional timber structures, e.g. the mortise-tenon and Dou-Gong joints. Seismic is one of the dynamic actions faced by these structures and will cause wood to suffer higher loading speeds than quasi-static loads. The investigation of the seismic strain rates (SSRs) effects of wood under perpendicular-to-grain compression (PTGc) is important. One hundred and forty-four radial small clear wood specimens were prepared using Dahurian larch, Mongolian pine and Chinese poplar. Monotonic and cyclic compression tests were conducted under three SSRs (10−3 s−1, 10−2 s−1, and 10−1 s−1) and the quasi-static strain rate (10−4 s−1). Failure modes, stress-strain curves, yield strengths, elastic moduli and the unloading/reloading moduli were analyzed. Results indicated that the PTGc properties were highly sensitive to SSRs under both the monotonic and cyclic compression. Strengths showed higher sensitivity to SSRs than elastic moduli. The SSRs effects of wood under cyclic compression have greater variability than the monotonic counterparts. The unloading/reloading moduli shows little SSR effects statistically. Comparisons were made between the existing PTG and the parallel-to-grain test results and a fitted general expression was obtained. Furthermore, an SSR-dependent stress-strain model was proposed and verified by tests.
摘要在中国传统木结构的许多关键部位,如榫卯和斗拱节点,木材主要承受横向压缩。地震是这些结构所面临的动力作用之一,它将使木材承受比准静态载荷更高的加载速度。研究木材在垂直压粒作用下的地震应变率(SSRs)效应非常重要。以大湖落叶松、油松和白杨为原料,制备了144个径向小清木标本。在3种SSRs(10−3 s−1、10−2 s−1和10−1 s−1)和准静态应变率(10−4 s−1)下进行单调和循环压缩试验。分析了试件的破坏模式、应力-应变曲线、屈服强度、弹性模量和卸载/再加载模量。结果表明,无论是单调压缩还是循环压缩,PTGc的性能都对SSRs高度敏感。强度对ssr的敏感性高于弹性模量。木材在循环压缩下的SSRs效应比单调压缩下的SSRs效应具有更大的变异性。卸载/重新加载模量在统计上没有明显的SSR效应。将现有的PTG与平行晶粒试验结果进行了比较,得到了拟合的一般表达式。在此基础上,提出了基于ssr的应力-应变模型,并进行了试验验证。
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引用次数: 0
The effect of the growth ring orientation on spring-back and set-recovery in surface-densified wood 生长环取向对表面致密木材回弹和凝固恢复的影响
IF 2.4 3区 农林科学 Q2 FORESTRY Pub Date : 2023-04-10 DOI: 10.1515/hf-2023-0004
A. Scharf, A. Lemoine, Benedikt Neyses, D. Sandberg
Abstract Wood under thermo-mechanical densification behaves differently depending on the cross-sectional growth ring orientation (GRO) relative to the direction of compression. This influences the degree of cell damage, but also the shape-memory effects occurring when the compression load is released (spring-back) and when the timber is re-moistened (set-recovery). To study how the GRO influences the shape-memory effects, Scots pine specimens were separated into three distinct groups of GRO (Flat, Inclined, Hybrid) and then thermo-mechanically surface-densified. Spring-back and set-recovery were determined by thickness measurements and by digital image correlation. A GRO parallel to the densified surface, resulted in a low spring-back and a high set-recovery which were uniform over the width of the specimen. Specimens with a GRO between 15 and 45° to the densified surface showed high spring-back and low set-recovery, indicating cell-wall damage. Spring-back mainly occurred in the non-plasticised region immediately below the heated surface region and elasto-plastic rolling-shear deformation along individual growth rings occurred. The GRO of softwood subjected to thermo-mechanical densification determines if an applied load results in rolling shear-deformation or radial compression. This in turn determines where in the cross-section and when in the process the cells deform and if this deformation occurs below or above the glass-transition temperature.
摘要木材在热机械致密化下的表现不同,这取决于相对于压缩方向的横截面生长环取向(GRO)。这会影响细胞损伤的程度,但也会影响压缩载荷释放(回弹)和木材重新润湿(恢复原状)时产生的形状记忆效应。为了研究GRO如何影响形状记忆效应,将苏格兰松标本分为三组不同的GRO(扁平、倾斜、混合),然后进行热机械表面致密化。回弹和凝固恢复通过厚度测量和数字图像相关来确定。平行于致密表面的GRO导致较低的回弹和较高的凝固恢复,这在试样的宽度上是均匀的。GRO与致密表面之间为15°至45°的样品显示出高回弹性和低凝固恢复性,表明细胞壁损伤。回弹主要发生在加热表面区域正下方的非塑化区域,沿单个生长环发生弹塑性滚动剪切变形。经过热机械致密化处理的软木的GRO决定了施加的载荷是否会导致滚动剪切变形或径向压缩。这反过来决定了细胞在横截面中的何处以及在该过程中何时变形,以及这种变形是否发生在玻璃化转变温度以下或以上。
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引用次数: 2
Wood as a hydrothermally stimulated shape-memory material: mechanisms of shape-memory effect and molecular assembly structure networks 木材作为一种水热刺激的形状记忆材料:形状记忆效应机制和分子组装结构网络
IF 2.4 3区 农林科学 Q2 FORESTRY Pub Date : 2023-04-10 DOI: 10.1515/hf-2022-0181
Y. Shao, Jian-fang Yu, Hui Liu, Yuhong An, Li-li Li, Zhang-jing Chen, Ximing Wang, Xiao-tao Zhang
Abstract This study aimed to evaluate the shape-memory effect (SME) of wood (Populus x beijingensis W. Y. Hsu) and identify the net-points and switches in its molecular and morphological structures. During several cycles of deformation and subsequent recovery, a high shape recovery rate and ratio were maintained. The transverse compression tests of wet and dry wood reveal that the hydrothermal coupling stimulation can considerably reduce the strength of wood. The X-ray diffraction characterization of wood under hydrothermal stimulation shows that the role of network nodes in the SME of wood is influenced by temperature. The wavenumber shifting and changes in the intensity ratio of the characteristic Fourier transform infrared peaks showed that hydrogen bonds acted as switches for the water-stimulated shape-memory behavior. By taking into account viscoelastic relaxation, a kinetic model derived from nonequilibrium thermodynamic fluctuation theory was used to describe the shape recovery process. The effects of hydration on recovery kinetics, activation, and dynamic mechanical behaviors were also studied. To explain the shape-memory mechanism of wood under hydrothermal stimulation, a hybrid-structure network model based on a single three-dimensional switch network was proposed in this study.
摘要本研究旨在评价北京杨树(Populus x beijingensis W. Y. Hsu)的形状记忆效应,并确定其分子和形态结构的网点和开关。在几次变形和随后的恢复循环中,保持了较高的形状恢复速率和比率。湿木材和干木材的横向压缩试验表明,水热耦合刺激会显著降低木材的强度。热液刺激下木材的x射线衍射表征表明,网络节点在木材SME中的作用受温度的影响。傅里叶变换红外特征峰的波数移位和强度比的变化表明,氢键对水激发的形状记忆行为起着开关作用。考虑粘弹性松弛,采用非平衡热力学涨落理论导出的动力学模型来描述形状恢复过程。研究了水化对回收动力学、活化和动态力学行为的影响。为了解释热液刺激下木材的形状记忆机制,本文提出了一种基于单一三维开关网络的混合结构网络模型。
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引用次数: 0
Frontmatter 头版头条
3区 农林科学 Q2 FORESTRY Pub Date : 2023-03-31 DOI: 10.1515/hf-2023-frontmatter4
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引用次数: 0
Building machine learning models to identify wood species based on near-infrared spectroscopy 建立基于近红外光谱的机器学习模型来识别木材种类
IF 2.4 3区 农林科学 Q2 FORESTRY Pub Date : 2023-03-30 DOI: 10.1515/hf-2022-0122
Li Luo, Z. Xu, B. Na
Abstract Efficient and nondestructive technology for identifying wood species facilitates the transition from digital forestry to smart forestry. While near-infrared spectroscopy applied to wood identification is well documented, the detailed mechanisms for chemometrics remain unclear. In this study, twelve wood species were identified by using near-infrared spectroscopy combined with six machine learning algorithms (support vector machine, logistic regression, naïve Bayes, k-nearest neighbors, random forest, and artificial neural network). Above all, isolated forest and local outlier factor were used to detect and exclude outliers. Then feature engineering strategies were developed from three perspectives to process feature matrices: feature selection, feature extraction, and feature selection combined with feature extraction. Next, the learning curve, grid search method, and K-fold cross-validation were used to optimize the model parameters. Finally, the accuracy, operation time, and confusion matrix were used to evaluate the model performance. When the local outlier factor was used to remove outliers and principal component analysis was used to extract features, the support-vector-machine-based wood-species identification model produced the most accurate results, with 98.24% accuracy. These results offer new avenues for constructing automatic wood-identification systems.
高效、无损的树种识别技术促进了数字林业向智能林业的过渡。虽然近红外光谱法用于木材鉴定有很好的文献记载,但化学计量学的详细机制仍不清楚。本文采用近红外光谱技术,结合6种机器学习算法(支持向量机、逻辑回归、naïve贝叶斯、k近邻、随机森林和人工神经网络)对12种木材进行了识别。最重要的是,使用孤立森林和局部异常因子来检测和排除异常值。然后从特征选择、特征提取和特征选择与特征提取相结合三个方面提出了特征工程策略来处理特征矩阵。其次,采用学习曲线法、网格搜索法和K-fold交叉验证对模型参数进行优化。最后用准确率、运行时间和混淆矩阵来评价模型的性能。当采用局部离群因子去除离群值,采用主成分分析提取特征时,基于支持向量机的树种识别模型准确率最高,达到98.24%。这些结果为构建木材自动识别系统提供了新的途径。
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引用次数: 0
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