快速检测木材微纤丝角的近红外光谱分析技术

介绍了一种新的测量木材微纤丝角的无损检测技术--近红外光谱分析,并详细阐述了测量时木材样品的选择及制备,测量工作包括X射线衍射和近红外光谱采集、多变量数据分析与模型建立的方法及步骤.证明了近红外光谱分析技术可以用于快速准确地预测木材的微纤丝角.     

开启木材细胞通道的途径

木材细胞通道畅通与否,直接关系到难干材的干燥、难浸渍防腐剂、阻燃剂木材的处理。开启木材细胞液体流动通道主要从纹孔膜入手,作者在前人研究基础上探讨了木材细胞液体移动形式及细胞通道开启的途径,归纳了3种开启木材细胞通道方式,一是采用化学处理,二是生物处理,三是借助外力(机械力、蒸汽力、冰冻力)等方式迫使木材细胞壁纹孔膜破裂,从而疏通或扩大细胞液体流动通道。阐述了每一细胞通道开启方式的适用范围以及实际操作中面临的问题,以便于能更好的运用到木材干燥、防腐、阻燃、染色等木材加工领域。     

中国主要人工林树种幼龄材与成熟材及人工林与天然林木材性质比较研究

本文对中国１０种人工林和４种天然林的幼龄材与成熟材及４个树种的人工林木材与天然林木材的构造特征、化学性质、物理性质、力学性质的３３项材性指标差异进行了比较研究。结果表明,在幼龄材与成熟材之间,在统计上表现出差异显著性的为幼龄材比成熟材生长轮宽,管胞列数多,管胞短,直径小,微纤丝角大,密度小,径向干缩小,差异干缩大,流体扩散性高,抗弯强度、抗弯弹性模量、顺纹抗压强度、径面顺纹抗剪强度、径面抗劈力和冲击韧性低等１５项,即４６％的测试项目差异显著;表明在木材加工和用作结构材时应将幼龄材和成熟材视作两个性质不同的总体来考虑,在培育结构材时应研究如何缩短幼年期或改善幼年期材性。在人工林与天然林木材之间,采取人工林幼龄材性质与天然林幼龄材性质相比,人工林成熟材性质与天然林成熟材性质相比,结果表明,多数性质在统计上差异不显著,只有人工林木材比天然林木材胞壁率小、顺纹抗压强度低、差异干缩大、流体扩散性高等４项,即只有１２％的很少数测试项目差异显著;表明有可能通过人工培育的方法培育出与天然林木材性质相近的木材。     

Decontamination of synthetic solutions containing heavy metals using chemically modified sawdusts bearing polyacrylic acid chains

New materials containing carboxylate groups have been synthesized by grafting polyacrylic acid onto sawdust. These new adsorbents were subjected to continuous extraction of different metal ions using packed columns to determine their maximum binding capacities. They exhibit binding capacities 15–40 times higher than unmodified sawdusts for removal of Cu²⁺, Ni²⁺, and Cd²⁺ chosen as representative heavy metal ions. Cation desorption and adsorbent regeneration could be effected by elution with a diluted HCl solution; water as an eluent has no effect on metal desorption.     

桉木抽出物中多酚化合物的特性研究

采用化学分析和光谱分析相结合的方法，从制浆造纸的角度，重点对雷林一号桉木的多酚化合物的特性进行了研究。结果表明：幼龄材的抽出物含量较少，适宜于制浆的采伐期为５～７年。１５年生雷林一号桉木心材中的多酚类化合物以水解单宁为主（占原料的５．９８％），其次为缩合单宁（１．９１％）。稀碱预处理桉木，可除去大部分多酚类化合物。存放过久的桉木中多酚化合物大部分变成‘黄粉’，既不溶于水也不溶于丙酮，只溶于稀碱或亚硫酸钠。桉木制浆前采用碱预处理可减轻多酚化合物对制浆产生的不良影响。     

数字图像处理技术用于木材微观分析的研究概况

随着现代计算机技术的飞速发展,计算机数字图像处理技术已经在很多行业和科研领域中得到了广泛的应用,而木材微观分析是木材科研领域中重要的基础研究,与以往木材微观科研利用光学显微仪器加上人眼进行观察测量的研究手段相比较,利用计算机数字图像处理技术对木材进行微观结构分析具有客观、准确、高效等诸多优点,成为木材微观科研领域中一项崭新的课题和本领域未来科研的发展方向。本文概括国内外计算机数字图像处理技术在木材微观分析中的研究进展、应用现状并对现有处理方法和已经进行的研究的优缺点进行阐述和分析。针对现有图像处理方法和现有的科研程度对计算机数字图像处理技术用于木材微观科研领域的前景和主要发展方向做了展望。     

Forest management and carbon sequestration in wood products

Wood products are considered to contribute to the mitigation of carbon dioxide emissions. A critical gap in the life cycle of wood products is to transfer the raw timber from the forest to the processing wood industry and, thus, the primary wood products. Therefore, often rough estimates are used for this step to obtain total forestry carbon balances. The objectives of this study were (1) to examine the fate of timber harvested in Thuringian state forests (central Germany), representing a large, intensively managed forested region, and (2) to quantify carbon stocks and the lifetime of primary wood products made from this timber. The analyses were based on the amount and assortments of actually sold timber, and production parameters of the companies that bought and processed this timber. In addition, for coniferous stands of a selected Thuringian forest district, we calculated potential effects of management, as expressed by different thinning regimes on wood products and their lifetimes. Total annual timber sale of soft- and hardwoods from Thuringian state forests (195,000 ha) increased from about 136,893 t C (~0.7 t C ha⁻¹ year⁻¹) in 1996 to 280,194 t C (~1.4 t C ha⁻¹ year⁻¹) in 2005. About 47% of annual total timber harvest went into short-lived wood products with a mean residence time (MRT) < 25 years. Thirty-one per cent of the total harvest went into wood products with an MRT of 25–43 years, and only 22% was used as construction wood and glued wood, products with the longest MRT (50 years). The average MRT of carbon in harvested wood products was 20 years. Thinning from above throughout the rotation of spruce forests would lead to an average MRT in harvested wood products of about 23 years, thinning from below of about 18 years. A comparison of our calculations with estimates that resulted from the products module of the CO2FIX model (Nabuurs et al. 2001) demonstrates the influence of regional differences in forest management and wood processing industry on the lifetime of harvested wood products. To our knowledge, the present study provides for the first time real carbon inputs of a defined forest management unit to the wood product sector by linking data on raw timber production, timber sales and wood processing. With this new approach and using this data, it should be possible to substantially improve the net-carbon balance of the entire forestry sector.     

速生杨木改性材力学及胶合性能的研究

采用氨溶季胺铜防腐剂(ACQ-D)和自制低分子酚醛树脂预聚体(PF),通过满细胞真空浸渍的方法对速生杨木进行了防腐和增强化学改性处理.对改性前后材料的基本力学强度性能,以及素材、增强改性材、防腐改性材和防腐增强改性材任两种材料的胶合强度进行了测试和分析.结果表明,试验范围内,防腐处理对材料的力学性能影响不大;PF增强改性材的抗弯弹性模量、抗弯强度、顺纹抗压强度、顺纹抗拉强度分别提高了97.11、83.36、125.53%、37.01%,防腐后增强改性材对应指标值分别提高了101.34、75.05、111.83%、32.60%,符合日本JAS标准中E类指标结构用材要求.PF增强改性材与其它材料进行胶合,压缩剪切胶合强度均大于11 MPa,木破率大于90%,能够满足日本集成材JAS标准的规定.     

Comparison of field sampling methods for assessing coarse woody debris and use of airborne laser scanning as auxiliary information

Coarse woody debris (CWD) has been recognized as one of the strongest indicators of forest biodiversity and its assessment has been emphasized in the development of new inventory methods. In this study, the most commonly referenced probability sampling methods were tested in a field area of 305.8 ha to gain comparative information on their performance and efficiency. Simple random sampling (SRS), systematic sampling and cluster sampling with fixed sized circular sample plots were tested, as well as strip sampling, transect relascope sampling and adaptive cluster sampling (ACS). Point relascope sampling and line intersect sampling were also tested for inventories of downed dead wood volumes. In addition, the amount of standing dead wood was assessed by means of traditional small angle relascope sampling. In general, the use of additional information in the inventory process has shown promising results. A new method for using data derived from airborne laser scanning (ALS) as a source of auxiliary information in the assessment of CWD volumes is presented, using probability proportional to size (PPS) sampling for the selection of the first-stage sample units in ACS (ACS_PPS) and for the placement of fixed sized plots (PLOT_PPS). The sampling methods were compared in terms of the cost-effectiveness. Point relascope sampling proved the most efficient sampling method for inventorying CWD volumes. PLOT_PPS and ACS_PPS were more efficient than the inventory of fixed sized plots (PLOT_SRS) and ACS (ACS_SRS) where sample units were selected with SRS. However, these methods could not achieve the same efficiency as relascope samplings. Nevertheless, the use of probability layers derived from ALS data gave promising results and offers new possibilities for inventorying CWD volumes more efficiently.     

微波处理中木材内温度分布的数学模拟

从热传导的物理规律出发,建立微波加热过程中木材内部热传导模型,并通过理论模拟揭示不同微波加热方式对预处理中木材内部温度分布的影响规律。结果表明:微波处理过程中,木材内部的温度分布规律及均匀性与微波加热方式直接相关;当采用单向微波辐射的方式进行加热时,沿着微波入射方向,木材温度逐渐降低,木材内部温差较大,且温度分布均匀性较差;当使用双向微波辐射的方式进行加热时,木材内能形成内高外低的温度梯度,且温度分布均匀性较好。