Effect of growing site,sampling date,wood location in trunk and drying method on concentration of soluble proanthocyanidins in Betula pendula wood,with special reference to wood colour

Proanthocyanidins (PAs), which are common phenolic compounds in plants, are considered to be mainly defensive compounds against different kinds of stress, e.g. herbivory. In addition to increasing after stress, they may condense and/or oxidize to form coloured compounds when cells die, which may affect both the resistance of xylem to rot and its colour. This is important in the mechanical wood industry. The effects of some biological factors (growing site, sampling date, wood location in the trunk) on the concentration of soluble PAs (sPAs) were studied in fresh and dried birch wood. Those factors that affected sPA concentration most were sampling date and radial location. Drying method also had a great effect on the sPA concentration, which in turn correlated with the colour of the wood.     

Restoration of dead wood in Basque stream channels: effects on brown trout population

Abstract – Streams in the Aiako Harria Natural Park (Basque Country, Spain) have excellent water quality, but are physically impoverished after centuries of snagging. In an attempt to restore channel complexity and ecosystem functioning, especially in‐channel retention of sediments and organic matter, large woody debris (LWD) was introduced into four mountain streams (channel width 3–13 m) following a before/after, control/impact (BACI) design. Logs were introduced by means of hand‐held machinery and located uncabled, mimicking the natural amount and disposition of LWD in streams. Floods disrupted most of the structures at the large stream, but caused little damage to those in the small ones. Only minnow and brown trout inhabit in the area. Before wood addition, trout densities were fairly high in the small streams, low in the large one, where recruitment seemed very poor. In the small tributaries, trout populations showed a strong imbalance towards young fish, adults being only found in the spawning season. Wood addition produced some interesting trends in trout, although statistical significance was low as a result of large environmental variability. Fish densities showed small changes, but biomass increased, especially in the spawning season. Also, there was a trend towards more aged 2⁺ or larger, thus suggesting wood addition improved adult habitat. Although restoring LWD is extremely unusual in Spain, the changes in physical habitat and the trends in fish populations detected in the present project suggest it is worth making more experiments, at least in safe settings where there is no risk of flooding or damaging properties.     

铜-季铵盐复配木材防腐剂的防腐性能

在实验室内采用常规的真空－加压法浸注试件，土壤木块法进行防腐试验，检验了铜－季铵盐类防腐剂（FFJ－1、FFJ－2和FFJ－3）对白腐采绒革盖菌[Coriolus versicolor(L.ex Fr.)Quel.]和褐腐绵腐卧孔菌[Poria placenta(Fr.)Cooke.]的防腐性能，结果表明：在较低的保持量下，都有较好的防腐效果。与百菌清（可湿性粉剂）、五氯酚钠、三唑酮相比较，它们对白腐菌的防腐性能与百菌清相近，批五氯酚钠和三唑酮好。     

Defense mechanisms in the sapwood of living trees against microbial infection

When pathogenic microorganisms invade living sapwood of woody plants, a series of defense responses occurs at the lesion margin. Putative active defense mechanisms include constitutive and induced inhibitory compounds, cell wall alterations, and occlusion of xylem elements. Active defenses play an important role in the sapwood, while constitutive and induced microenvironmental conditions in the wood might also constrain pathogen development. It is necessary to develop a unified understanding, in which these factors could act synergistically and provide effective defense barriers.     

Study on Drying Characteristic of Chinese Fir and Poplar Plantation Wood

The drying characteristic was studied for plantation wood of Chinese fir and poplar, which are typical plantation wood of southern and northern part of China, respectively. Through 100-degree-method the drying characteristic and basic drying condition were gotten, then drying schedule was developed for practical drying, the results showed that the drying schedule is suitable for Chinese fir and poplar plantation lumber, but shrinkage is large. The recommendation was made that enough dead weight is needed to decrease shrinkage in drying process. The drying quality of the two species of lumber is good in conventional drying method.     

改性胶粘剂对稻壳-木材复合材料性能影响的研究

稻壳的外表面覆盖有二氧化硅膜,使用传统的脲醛树脂(UF)和酚醛树脂胶(PF)生产的100％的稻壳板难以达到木质刨花板的质量指标。本研究采用以异氰酸酯(ISO)改性的脲醛树脂和酚醛树脂胶制造稻壳-木材复合材料。稻壳与木片的混合比例为1:1,施胶量为7％,设计密度0.8g/cm3。试验结果表明,3:4的ISO/UF、2:5的ISO/PF、改性胶粘剂制备的板材的物理力学性能达到国标刨花板二等品的要求;用3:4的ISO/PF改性胶粘剂制备的板材达到优等品的要求。     

Water Sorption Behaviors of Five Woods above Fiber Saturation Point

Woods from Korean Larch, Chinese Fir, Aspens, Manchumian, and Fortunes Paulownia were chosen for investigation. Specimens cut from the air-dried woods had a cubic shape with nominal air-dried size of 17.0 mm and 8.5 mm. Oven-died specimens were put in containers filled with water and water sorption was implemented at atmospheric pressure and room temperature. Results from the experiment could not described exactly by the model of steady state flow from Darcy' law. An empirical equation is put forward for the relationship between the water uptake and immersion time. Meanwhile the immersion time for the maximum water uptake (MWU) was predicted from the water sorption rate. The water sorption behaviors above the fiber saturation point (FSP) differed among five tested woods. Size of specimens had an influence on the water sorption. Small specimens reached their MWU more quickly than large specimens, while large specimens have a higher water sorption rate than those of small ones. MWU was estimated, and the     

STUDY ON THE EFFECT OF WOOD MOISTURE CONTENT ON PERMEABILITY IN THE HYGROSCOPIC RANGE

Woodpermeabilityhascloserrelationshipwiththemanyfiledsofwoodworkingandusing,woodfluidpermeabi1-ityisrelatedtoinprocessingsuchaswooddrying;fireretartenttreatmen;pup1ingandpaper;woodpreservation.Theflowoffluidinwoodincludestwokindsoftransportprocess.Oneispenetrationfromwoodoutsidetoinside,suchas'woodpreservationandfireretartenttreatment,anotherisdiffusionfromwoodinsidetooutside'suchaswooddrying,Infact,woodpermeabilityinfulenceddirectlythequalityofwoodwaterheattreatment,Forthisreasontheresearchin…     

Improvement of wood properties by urea-formaldehyde resin and nano-SiO2

In order to improve wood properties of triploid clones of Populus tomentosa, urea-formaldehyde (UF) resin was compounded with nano-SiO₂, coupling agents and flame retardants in different ways to prepare five kinds of modifiers. The poplar wood samples were impregnated with the modifiers and heated to prepare UF-SiO₂-wood composites. The antiswelling efficiency, resistance of water absorption, oxygen index and hardness of the composites were measured. Results show that all of the modifiers reduced water absorption of poplar wood and enhanced flame resistance and hardness. Nano-SiO₂ showed a marked effect in improving the hardness of wood. In addition, all of the modifiers, except UF-C-SiO₂-polymer, improved the dimensional stability of poplar wood. The UF resin and nano-SiO₂ compound improved general properties of poplar wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(2): 123–128 [译自: 北京林业大学学报]     

γ射线辐射杉木压缩木材的固定和蠕变(英文)

为了探讨木材压缩变定固定的机理 ,该研究对杉木压缩木材进行γ射线辐射处理 ,射线辐射剂量分别为 0 (作为对照试材 ) ,10 3 ,5× 10 3 ,10 4 ,5× 10 4 ,10 5,5× 10 5,10 6,5× 10 6Gy ,然后测定和讨论了γ射线辐射杉木压缩木材的重量损失率、平衡吸湿含水率 (EMC)、吸湿回复率 (RSA)和吸水回复率(RSW )、绝干状态下和吸湿解吸过程中的蠕变。该研究表明 :γ射线的辐射剂量对杉木压缩木材的重量损失率、EMC、RSA、RSW有重要的影响 ,当辐射剂量超过 10 6Gy后 ,试材的重量损失率和EMC显著增大 ,RSA和RSW显著下降 ;另外 ,随着γ射线辐射剂量的增大 ,绝干状态和吸湿解吸过程中杉木压缩木材的瞬时柔量和蠕变柔量均呈增大趋势 .从该研究结果可以推测 ,当γ射线辐射剂量较大时 ,特别当辐射剂量在 5× 10 6Gy左右时 ,杉木压缩木材的细胞壁中发生了降解反应或非结晶化反应 .而且 ,该研究证明了压缩木材细胞壁主成分发生的降解反应能够使木材压缩变定得到一定程度的固定