Liquid penetration of precompressed wood VII: combined treatment of precompression and extraction in hot water on the liquid penetration of wood

The object of this study was to determine the cause of differences in the improvement in liquid penetration of precompressed wood species. The maximum amount of water uptake by the capillary rise method and changes in the aspirated pits seen with scanning electron microscopy before and after of preextraction and precompression were investigated using heartwood samples of four softwoods. The height of penetration and the weight by the capillary rise method for preextractive wood powders are discussed. Three wood species andLarix leptolepis showed marked increases in the amount of solution uptake after precompressed treatment only.Larix leptolepis wood required compression after extraction by boiling in water. These differences among wood species were caused by the accumulation of extractive material. It was also recognized that the accumulative material inLarix wood has plasticity and that inPseudotsuga is brittle. Based on these results it was found that it is difficult to destroy aspirated pits in the former and easy in the latter. On the other hand, the difference in penetration of each wood species was caused by the quantity and quality of the extraction material in addition to the extent of the wettability of the surface of the cell cavity as well as aspirated pit.Part of this report was presented at the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 1996     

Magnetic resonance imaging used for the evaluation of water presence in wood plastic composite boards exposed to exterior conditions

Abstract

Two wood plastic composite (WPC) boards, one experimental and one commercial, were exposed to exterior conditions and evaluated non-destructively using a clinical magnetic resonance imaging (MRI) unit for moisture content (MC) and distribution. The experimental board was exposed in Vancouver, British Columbia, for more than 8 years, and the commercial board was exposed near Hilo, Hawaii, for 2 years. Both boards were characterized in terms of wood content, density, water uptake properties and voids content. The experimental board was additionally destructively analysed for water absorption of the WPC and MC calculated based on the wood content for verification of MRI results. MRI detected the presence of free water and its distribution in both of the WPC boards. Fibre saturation in the experimental board was found to be about 22–24%, in comparison to 25–30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Magnetic resonance images showed various major points of water entry in the WPC boards such as the support area, the cut ends, the dripping edge and the sides of the boards. For the experimental board, significant water entry also occurred at the upper exposed surface.     

Volatile organic compounds from wood and their influences on museum artifact materials I. Differences in wood species and analyses of causal substances of deterioration

Wood is generally used as the interior material in museum storage rooms. Recently, however, the effects of volatile organic compounds (VOCs) from wood on artifacts has become a topic of great concern. The VOCs from four species of wood (western red cedar, spruce, kiri, and sugi) and their effects on artifact materials (two types of metal, seven types of pigment) were investigated using a deterioration-accelerating test, gas chromatography-mass spectrometry, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The results suggested that the influences on artifact materials varied greatly with wood species, and depended on specific components such as hinokitiol or acetic acid rather than the amount of total volatile organic compounds (TVOCs). It is a very serious problem that of the four species of wood, western red cedar (rich in hinokitiol), which has been recommended as an interior material for museum storage rooms, showed the heaviest deterioration on metal samples, and only this type of wood discolored enpaku (white lead) and rokushou (malachite, verdigris). In such storage rooms, museum artifacts should be carefully monitored. When selecting an interior material for a storage room or studying methods of preventing deterioration, it is very important to consider fully the characteristics of wood VOCs, not only the amount of TVOC.Part of this paper was presented at the 24th (Tokyo, June 2002) and 25th (Kyoto, June 2003) Annual Meeting of the Japan Society for the Conservation of Cultural Property     

超声波木材缺陷检测固体耦合剂(橡胶)的试验

采用不同密度和配比的软橡胶(橡皮),通过测得其厚度的改变对超声波接收信号强弱的影响,证明软橡胶这种固体材料作为耦合剂的替代品是适合的.橡胶耦合材料的使用避免了常规半固态耦合剂在使用中存在的问题.     

Study of the release in water of chemicals used for wood preservation. Effect of wood dimensions

Summary Various chemicals are used for protecting wood samples against fungi, and some of them are released in water, leading to pollution of the water. The kinetics of pentachlorophenol release in water has here been studied by considering the diffusion through the wood along the three principal axes of diffusion. The experiments and the modelling of the process is successfully coupled. The numerical model takes into account the three principal diffusivities, the partition factor, the volumes of wood and water. The effect of wood sample length along the longitudinal axis of diffusion is studied especially, as longitudinal diffusivity is much higher than the other two principal diffusivities. The effects of the relative volumes of wood and water are also of considerable interest not only for the concentration of the chemical in water but also for the rate of release.Symbols C concentration of liquid (g/cm³)_ - C _c ,C _eq concentration of liquid on the surface, at equilibrium with the surrounding, respectively - C _i,j,k concentration of liquid in the wood at positioni, j, k - D diffusivity (cm²/s) - h coefficient of mass transfer on the surface (cm/s) - K partition factor - i, j, k integers characterizing the position in the wood - M _L ,M _R ,M _T dimensionless numbers - M _t ,M amount of chemical released after time t, after infinite time, respectively - t increment of time - L, R, T thickness of the slices taken in the wood for calculation - N _L ,N _R ,N _T number of slices taken in the wood - x, y, z coordinates - V _water volume of the surrounding water     

Evaluation of the distribution of water in wood by use of three dimensional proton NMR volume imaging

Summary This work confirms that there is sufficient water in wet wood to provide an adequate signal level for detection by NMR-imaging; furthermore, its natural line-width is sufficiently small that these experiments can be performed with modest levels of the imaging gradients. Second, it is clear that this water is sufficiently accessible to chemical reagents introduced from the outer surface of the wood, that the location of such reagents can be established by the perturbations they induce in the properties of the wood-water itself. In this regard, the water is acting effectively as a molecular amplifier for the reagent; as a result, the effect of low concentrations of, for example, fungicides, bacteriostatic reagents and other preservatives can easily be followed.It is a pleasure to thank the Natural Science and Engineering Research Council of Canada for their support of this work via an equipment grant in the New Research Ideas Category, and more recently by a Strategic Grant (Number G 1508). V.R. wishes to thank UBC for a University Graduate Fellowship     

Study of the release in water of a chemical used for preservation of wood. Effect of the dimensions of the wood

Summary Various chemicals are used for protecting wood samples against fungi, and some of them are released in water, leading to pollution of the water. The kinetics of release of pentachlorophenol in water has here been studied, by considering the diffusion through the wood along the three principal axes of diffusion. The experiments and the modelling of the process is successfully coupled. The numerical model takes the three principal diffusivities, the partition factor, the volumes of wood and water into account. The effect of the length of the wood sample taken along the longitudinal axis of diffusion is especially studied, as the longitudinal diffusivity is much higher than the other two principal diffusivities. The effect of the relative volumes of wood and water is also of considerable interest not only for the concentration of the chemical in water but also for the rate of release.Symbols C concentration of liquid (g/cm³) - C_s, C_eq,t concentration of liquid on the surface, at equilibrium with the surrounding, respectively - C_i,j,k concentration of liquid in the wood at position (i, j, k) - D diffusivity (cm²/s) - h coefficient of mass transfer on the surface (cm/s) - i, j, k integers characterizing the position in the wood - K partition factor - L, R, T dimensions of the parallelepipedic wood sample - Mini amount of chemical contained in the wood at the beginning of the desorption - M_L, M_R, M_T dimensionless numbers - M_t, M amount of chemical released up to time t, up to infinite time, respectively - N half-number of slices taken in the wood parallelepiped along each dimension - V_water volume of the surrounding water - x, y, z coordinates - L, R, T thickness of the slices taken in the wood for calculation - t increment of time     

Heating and temperature distribution under cyclic deflection in the non-linear region for wood

Summary Temperature distribution during a fatigue process was examined under cyclic deflection in the non-linear region. The cyclic deflection caused a remarkable and local rise in temperature by the heating due to viscosity of air-dried wood. The appearance of the peak in temperature versus the logarithmic cyclic number was explained on the basis of viscosity change due to moisture movement and vaporization by heating during the fatigue process. The change of the temperature distribution was related to the heat transfer and the heat capacity of wood.     

Composition, distribution and supposed origin of mineral inclusions in sessile oak wood — consequences for microdensitometrical analysis

SEM and light-microscopical observations, supported by chemical microanalysis with an EDXA system, revealed that light-saturated pixels observed in X-ray negatives of sessile oak (Quercus petraea Liebl.) wood were caused by inorganic deposits present inside multiseriate ray and axial parenchyma cells. Calcium oxalate crystals, silica grains and amorphous granules with varied mineral compositions have been identified. The wood strips of three out of six sampled trees contained measurable amounts of mineral inclusions which were quantified using image analysis. Based on the variations of mineral content observed between trees and within and between annual rings of the same tree, some hypotheses were formulated concerning the factors involved in the formation of inorganic deposits in oak wood. Their occurrence varies depending on the mineral concerned and seems to be controlled largely by a tree effect. The time of formation appears to coincide with a shifting of the oak wood’s functions as a result of heartwood formation processes (inter-annual scale) or changes in leaf phenology and climate (intra-annual scale). In addition, the technical consequences of their presence as well as their effects on wood density measurements through microdensitometry are discussed.     

Volatile composition analysis by solid-phase microextraction applied to oak wood used in cooperage (Quercus pyrenaica and Quercus petraea): effect of botanical species and toasting process

The purpose of this study was to investigate the sorption of selected volatile substances from oak wood-chip samples (Quercus pyrenaica Willd. and Quercus petraea L.) subjected to different toasting levels, namely, without toasting, with medium toasting, and with strong toasting, through the use of solid-phase microextraction (SPME). The main volatile compounds identified as a function of the toasting level and botanical species were furfural, hexanal, α-pinene, d-limonene, decanal, vitispirane, ethyl hexanoate, cis-3-methyl-γ-octalactone (“oak lactone” or “whisky lactone”), α-terpineol, p-xylene, and nonanal. Considering the data obtained from the toasted woods (medium and strong intensity) in comparison with those of nontoasted woods, it can be pointed out that the average peak area and the number of compounds identified in the gas chromatogram decreased during the toasting process. In general, regarding the compounds analyzed, quantitative differences were found between the two oak wood species under study. High values of volatile compounds were found in Quercus pyrenaica oak wood chips. In addition, for the number of compounds identified in oak wood extracts and directly extracted from solid oak wood chips by SPME, it is concluded that the best extraction process for volatile compounds from oak wood is the use of oak wood-chip liquid extracts.     

Kinetic analysis of color changes in keyaki (Zelkova serrata) and sugi (Cryptomeria japonica) wood during heat treatment

The kinetics of color changes in keyaki (Zelkova serrata Makino) and sugi (Cryptomeria japonica D. Don) wood during heat treatment were examined. The color of wood specimens treated at 90, 120, 150, and 180 °C was measured by an imaging spectrophotometer and expressed using CIELAB color parameters. At any treatment temperature, values for L* and $ \Updelta E_{ab}^{*} $ decreased and increased in both wood species, respectively, with increased treatment time. Changes in a* and b* varied depending on wood species and treatment temperature. The color changes were successfully analyzed using the kinetic approach applying time–temperature superposition method. This approach elucidated and accurately predicted color changes during heat treatment.     

Thioacidolytic analysis of residual lignins isolated from the chemical pulps of spruce (Picea abies) and beech (Fagus sylvatica) wood

Eight different residual lignins isolated from unbleached chemical pulps [sulfite, kraft, alkaline sulfite-anthraquinone-methanol (ASAM), soda/AQ/MeOH] of spruce and beech were characterized using gel permeation chromatography (GPC), thioacidolysis, and desulfurization to determine average molecular weight, amounts of uncondensed β-O-4 linkages, and dimeric linkage patterns, respectively. The total amounts of G-CHSEt-CHSEt-CH₂SEt and S-CHSEt-CHSEt-CH₂SEt were markedly reduced in residual lignins to 40% to 80% of the values for the corresponding milled wood lignins (MWLs). The number of dimeric units determined by thioacidolysis and desulfurization of the residual lignins was decreased by onehalf to one-fifth compared to the MWLs. Among the diverse types of dimeric units, reduction of β-1 and β-5 units was significant in most of the residual lignins, with the exception of beech ASAM residual lignin. Compared to beech MWL, 40% more C6–C3 main monomers were detected, whereas the relative composition of the dimeric units in the beech residual lignin was very similar to that in the beech MWL. The average molecular weights of residual lignins were less than those of the MWLs. However, the average molecular weights of the spruce kraft and soda residual lignins were determined to be higher than those of the corresponding MWLs.     

The analysis of life data for wood in the bending mode

Summary The applicability of a proposed procedure based on accepted, reliable, statistics was evaluated for characterizing the duration of load properties of wood in bending. By subjecting small, clear, wood specimens to several constant stress levels, it was experimentally demonstrated that the proposed procedure is capable of estimating, at an acceptable level of confidence the maximum service life beyond which a specified proportion of the nominal population will survive. The extension of this procedure to structural sized members seems plausible, since an estimate of the short term ultimate strength for each specimen is not required. Another attribute of the procedure is that parametric estimates can be computed without failing all of the specimens; thus this should significantly reduce the duration of load test time.The work reported here was completed while the author was a graduate research assistant in the Materials and Science and Engineering Department, Wahington State University. The author gratefully acknowledges the many fine comments he received from the referees. Particular thanks go to Dr. James A. Lechner, Center for Applied Mathematics, National Bureau of Standards and Professor Sam C. Saunders, Department of Mathematics, Washington State University     

Utilization of polar metabolite profiling in the comparison of juvenile wood and compression wood in loblolly pine (Pinus taeda)

Juvenile wood (JW) of conifers is often associated with compression wood (CW), with which it is sometimes believed to be identical. To determine whether JW and CW can be distinguished metabolically, we compared gas chromatographic profiles of 25 polar metabolites from rooted cuttings of a single loblolly pine (Pinus taeda L.) clone raised in controlled environment chambers and subject to three treatments: (1) grown erect with minimal wind sway (control); (2) swayed by wind from oscillating fans; and (3) with 30-cm growth increments successively bent at an angle of 45 degrees to the vertical. Profiles were compared by principal component analysis. Substantial increases in abundances of coniferin and p-glucocoumaryl alcohol separated immature JW-forming xylem tissues of the control trees from the CW-forming xylem of the bent and swayed trees.     

加工活性炭处理松材线虫病死木技术的研究

经３ａ的试验和实践结果表明，加工活性炭处理松材线虫病死木中松褐天牛成、幼虫等媒介昆虫是一项简单易行、灭害彻底、效益较高的处理松材线虫病死木的新技术，值得在疫区推广应用。     

Method for evaluating the influence of wood machining conditions on the objective characterization and subjective perception of a finished surface

A method for evaluating the influence of the operating parameters of wood machining (planing, sanding) on the quality of a finished surface was established. The influence of each of the operations involved was studied using different strategies. For the planing operation, three levels were established (Level 1, 2 and 3) by determining different values for each of the major process parameters (tool rotation speed, feed speed, depth of cut). For both, surface preparation and polishing, two levels were established with a fixed setup. Finally, as finishing products, two different transparent coatings were selected (water-borne and solvent-borne). The quantitative evaluation of the state of the surface was assessed by means of an artificial vision system for the determination of the pseudo-roughness of wood surfaces. A filtering method based on fast Fourier transforms was applied and it was possible to derive three criteria for evaluating the resulting profile.     

Chemical treatment of wood for musical instruments. Part I: acoustically important properties of wood for the Ranad (Thai traditional xylophone)

The purpose of this study is to determine the important acoustic properties of wood for making Ranad bars and the resonator box. The woods used in this study were separated into two groups. The first group is the type of wood that has been used to make Ranad for centuries: Ching-Chan (Dalbergia oliveri Gamble) and Ma-Had (Artocarpus lakoocha Roxb.) for making the bars, and Ka-Nun (Artocarpus neterophylla Lamk.) out of which the resonator box is made. The second group comprises woods that are abundant in Thailand and are genetically related to the first group. The physical and mechanical properties of the woods in both groups were measured including the specific dynamic Youngs modulus (E/), density (), hardness (H), acoustic conversion efficiency (ACE), and sound refraction coefficients (||). The results revealed that high and consistent || were crucial factors of the Ranad bar properties in addition to E/, , and H. The results from measurements made on the resonator box wood revealed that high E/, ACE, and high and consistent || were its crucial properties.     

Application of the fractometer for crushing strength: juvenile-mature wood demarcation in Taiwania (Taiwania cryptomerioids)

The fractometer is a device that breaks a radial increment core along the fiber for the measurement of crushing strength, which is a direct wood quality indicator for structural lumber. In this study, the crushing strength of Taiwania (Taiwania cryptomerioides Hay) trees using the fractometer was investigated and the data were used to determine the position of demarcation between juvenile and mature wood. Segmented regression and variance component analysis were used to estimate the demarcation position. With increasing cambium age, the core wood improves the crushing strength in the outer wood area. Within-tree variations in wood properties were greater than between-tree variations. In this experiment, the position of demarcation between juvenile and mature wood occurred at an approximate distance of 10.8cm to 13.2cm from the pith at about 18–20 years of cambium age.     

松材线虫对湖南林业和生态环境影响的风险性分析

遵循国际植物保护公约（IPPC）制定的有害生物分析准则，结合森林植物检疫对象的特点，从地理和管理标准、传入、定殖、定殖后扩散的可能性、潜在的经济和环境重要性在对松材线虫传入湖南进行了风险分析。证明松材线虫完全符合检疫性有害生物地理和管理标准，随松类植物及产品的调运从国内外疫区传入的可能性极大，在湖南完全能够定殖，定殖后能迅速扩散并暴发成灾，不仅对全省林业生产影响极大，而且严重威胁世界自然遗产武陵源风景区的安全,提出了3种降低风险的管理措施。