生物弹性轻软微米木纤维材料应用前景

介绍了生物弹性轻软微米木纤维材料(简称BEWM).BEWM属于生物医用材料的一个分支,它是一种在医学和其它与人直接接触的行业得到广泛应用的新型木质材料,在未来医学、汽车、飞机等与人有密切联系的行业具有巨大的推广应用空间.BEWM具有可塑性、韧性、弹性、易透性、吸附性及通透性,质地轻且表感松软.现阶段,木材是最便宜、实用的生物弹性轻质材料,它将是BEWM的天然基材,具有吸附性及通透性,人的皮肤在和BEWM接触时不会患上皮炎和毛囊炎.BEWM的易透性极好,完全能被X射线穿透,其本身没有任何辐射和污染,是纯天然可再生的材料.目前,生物材料学是生命科学学科中最具发展潜力的分支学科,BEWM是这个分支学科的一个研究方向.     

小波分析在中密度纤维板无损检测中的应用

以中密度纤维板为试件,通过纵向共振和弯曲振动试验讨论小波分析方法用于无损检测的可行性.结果表明:小波分析得到的中密度纤维板试件动弹性模量与常规弯曲静弹性模量在0.01水平下相关性非常显著,可以用小波分析方法测得的动弹性模量来表征常规弯曲静弹性模量;可以用小波分析的方法判断出试件是否有缺陷,小波分析在试件缺陷无损检测方面具有优越性.     

基于横向振动法对樟子松木材进行应力分等的研究

以樟子松木材为试验对象,分别运用横向振动法和静态弯曲法得出其动态弹性模量和静态抗弯弹性模量,重点对二者的关系以及尺寸、节子等因素对动态弹性模量的影响进行了研究.其结论是：动态弹性模量与静态抗弯弹性模量以及抗弯强度都有很好的相关关系;尺寸对动态弹性模量没有显著性的影响;节子的个数对木材动态弹性模量有显著性影响.     

两次铺装玻璃纤维布对刨花板性能的影响

在普通的玻璃纤维布增强刨花板中，玻璃纤维受刨花挤压呈弯曲的波浪状态，降低了玻璃纤维布的增强作用，本研究采用二次成型法可较好地发挥玻璃纤维的增强作用，静曲强度和弹性模量比普通增强刨花板提高１０％左右，施加偶联剂也可以提高玻璃纤维布增强刨花板的强度。     

Finite element study of growth stress formation in wood and related distortion of sawn timber

Lack of straightness in timber is the most frequent complaint regarding solid (and laminated) timber products worldwide. Nowadays, customers demand higher quality in the shape stability of wood products than they did earlier. The final distortion of timber boards is mostly caused by moisture-related stresses in wood (drying distortions) and growth-related stresses (distortions appearing when logs are split up to timber boards by sawing). To get more knowledge on how these distortions can be reduced in wooden products, there is a need for improved understanding of this material behaviour through good numerical tools developed from empirical data. A three-dimensional finite element board distortion model developed by Ormarsson (Doctoral thesis, Publ. 99:7, 1999) has been extended to include the influence of growth stresses by incorporating a one-dimensional finite element growth stress model developed here. The growth stress model is formulated as an axisymmetric general plane strain model where material for all new annual rings is progressively added to the tree during the analysis. The simulation results presented include how stresses are progressively generated during the tree growth, distortions related to the redistribution of growth stresses during log sawing, and distortions and stresses in drying reflecting the effects of growth stresses. The results show that growth stresses clearly vary during tree growth and also form a large stress gradient from pith to bark. This in itself can result in significant bow and crook deformations when logs are sawn into timber boards. The distortion results from the simulations match well with the results observed in reality. The parametric study also showed that the radial growth stress distribution is highly influenced by parameters such as modulus of elasticity, micro fibril angle and maturation strain.     

Development and evaluation of a support system for forest education

Field education programs have been conducted throughout the world because learning through experience is an important process in environmental and forest education. We developed a support system for forest education that consists mainly of a Global Positioning System (GPS) and personal digital assistant (PDA). Moreover, field experiments were conducted to evaluate educational efficacy as well as usability of the developed system. Through a post-questionnaire the developed system was highly evaluated in terms of educational efficacy and enjoyment. On the other hand, the questionnaire revealed the need for technical improvements. For example, the drawing function, which involves the use of a stylus pen, was the most poorly evaluated because a drawing could not be partially erased as with an eraser and representation was not sufficiently accurate. In addition, positions where information on nature appeared were sometimes inaccurate due to positional errors caused by using the autonomous GPS. Some participants answered that walking with the developed system was also troublesome due to its shape and size. In fact, they did not feel comfortable about the cables connecting the GPS to the PDA and GPS to its antenna. Although there were some problems with the system, we believe that the field education program was successful because 95% of the participants answered that they would join a similar program again.     

树皮未被发现的力学功能

本文从生物的功能适应性原理出发,选取杉木和落叶松为研究对象,验证其力学的功能适应性原理.试验结果表明,树干的密度及抗拉、抗压强度都呈现出沿陉向递增的趋势,树皮的强度明显降低,且不符合该原理.但研究发现,树皮显著提高了树木抗冲击的能力,使带皮木材的冲韧性提高了约1/3.     

Ring-level models for predicting wood and fibre properties of Abies balsamea

Wood and fibre properties such as wood density, microfibril angle, and modulus of elasticity are industrially relevant factors in determining the mechanical properties of wood. Radial ring-level predictive models of these properties were developed using balsam fir data from a long-term trial in New Brunswick (Canada), where precommercial thinning was applied 8 years after the site was harvested. The mixed effects models developed accounted for most of the variability in wood density (68 %), microfibril angle (94 %), and modulus of elasticity (77 %) with low RMSE. This study shows that balsam fir wood and fibre properties are strongly related to distance from the pith, particularly in the first 20 mm, and much less to annual ring width. Disk height and selected weather variables related to air temperature during the growing season significantly improved the models, whereas the effect of precommercial thinning was not significant. These equations can be incorporated into computer models, such as Optitek, that simulate mill recovery and wood properties to obtain accurate information on wood products. The unexplained variation in these models is likely related in part to between-tree genetic variation, which is unknown in this study.     

Developing and evaluating a multisite and multispecies NIR calibration for the prediction of Kraft pulp yield in eucalypts

Over recent years the application of near infra-red (NIR) spectroscopy to the prediction of wood properties has been demonstrated in many proof-of-concept studies. Previous work has demonstrated that NIR measurements can be used to predict basic density from woodmeal, chainsaw dust and solid wood, as well as microfibril angle and modulus of elasticity in solid samples. For over a decade, the prediction of Kraft pulp yield (KPY) has been a constant research focus, and numerous small studies have demonstrated this potential. However, because of the cost of obtaining calibration samples with known KPY, sample numbers are typically less than 100. While the potential for NIR prediction of KPY is well recognised, the shift to routine commercial use has not occurred. There still remains considerable scepticism in the research and industry communities about the use of NIR. Concern is typically expressed in two areas: (1) the consistency, accuracy and precision of predictions and (2) the need to prepare a separate calibration for each site and/or species group. To elevate NIR from proof-of-concept to a pilot scale, a large multisite, multispecies calibration was developed over iterative cycles to: (1) determine whether KPY in eucalypts can be predicted from a single calibration independent of site and species, and (2) identify the potential limits of accuracy and precision. This paper reports the results of the first seven testing cycles. The NIR calibration was expanded from an initial sample set of 104 mixed eucalypt samples to over 720 samples covering more than 40 species from predominantly temperate sites across Australia. The performance of the final calibration using two independent and contrasting data sets showed that a multisite and multispecies calibration is feasible. The expected potential accuracy and precision that can be expected from NIR predictions is discussed.     

Modeling the dynamics of pressure propagation and diameter variation in tree sapwood

A non-steady-state model of water tension propagation in tree stems was developed. The model is based on the cohesion theory and the assumption that fluctuating water tension driven by transpiration together with the elasticity of wood cause variations in the diameter of a tree stem. The change in xylem diameter can be linked to water tension in accordance with Hooke's law. The model was tested against field measurements of the diurnal change in xylem diameter at different heights in a 180-year-old Scots pine tree at Hyyti?l?, southern Finland. Model predictions agreed well with measurements. The effect of tree dimensions on pressure propagation was examined with the model. The model outcomes were also consistent with results of several field measurements presented in the literature.     

漆树酶的固定化——Ⅳ.固定化漆树酶催化陈漆复活制备“超级生漆膜”

研究了两种固定化漆树酶(聚丙烯酰胺包埋漆树酶和ABSE-交联琼脂共价偶联漆树酶)催化陈漆漆酚氧化聚合,实现了“陈漆复活”。首次制备了室温自干的“超级生漆膜”。它的8项物理性能指标:流平性、干燥不受湿度的影响性、实干速度、色泽、光泽值、冲击强度、柔韧性(弹性)和附着力在不同程度上均超过了一般生漆膜。这种固定化漆树酶催化漆酚氧化聚合的技术路线使本来纠缠在一起的复杂的生漆成膜过程分解为比较单一的漆酚氧化、聚合过程和线性聚合物交联过程,因而有利于彻底弄清生漆成膜的反应机理,也有利于阐明天然生漆各组分如胶质(树胶质)等对生漆成膜的贡献。     

Optical properties of bud scales and protochlorophyll(ide) forms in leaf primordia of closed and opened buds

The transmission spectra of bud scales of 14 woody species and the 77 K fluorescence emission spectra of the innermost leaf primordia of closed and opened buds of 37 woody species were studied. Pigment concentrations were determined in some species. Bud scales had low transmittance between 400 and 680 nm with a local minimum around 680 nm. Transmittance increased steeply above 680 nm and was > 80% in the 700-800 nm spectral region. Significant protochlorophyllide (Pchlide) accumulation was observed in leaf primordia of tightly packed, closed buds with relatively thick, dark bud scales. In common ash (Fraxinus excelsior L.) and Hungarian ash (Fraxinus angustifolia Vahl.), the innermost leaf primordia of the closed buds contained protochlorophyll (Pchl) and Pchlide (abbreviated as Pchl(ide)), but no chlorophyll. We observed Pchl(ide) forms with emission maxima at 633, 643 and 655 nm in these leaves. Complete transformation of Pchlide(655) (protochlorophyllide form with maximum emission at 655 nm) into Chlide(692) (chlorophyllide form with maximum emission at 692 nm) occurred after irradiation for 10 s. The innermost leaf primordia of the buds of four species (flowering ash (Fraxinus ornus L.), horse chestnut (Aesculus hippocastanum L.), tree of heaven (Ailanthus altissima P. Mill.) and common walnut (Juglans regia L.)) contained Pchl(ide)(633), Pchl(ide)(643) and Pchlide(655) as well as an emission band at 688 nm corresponding to a chlorophyll form. The Pchlide(655) was fully photoactive in these species. The outermost leaf primordia of these four species and the innermost leaf primordia of 28 other species contained all of the above described Pchl(ide) forms in various ratios but in small amounts. In addition, Chl forms were present and the main bands in the fluorescence emission spectra were at 690 or 740 nm, or both. The results indicate that Pchl(ide) accumulation occurs in leaf primordia in near darkness inside the tightly closed buds, where the bud scales and the external leaf primordia function as optical filters.     

丹东野生香百合的组织培养和快繁技术研究

对丹东地区野生香百合的组织培养进行了研究。结果表明：以球根鳞片做外植体培养在MS＋BA 1．0 mg/L ＋ NAA 0．4 mg/L培养基上可诱导出小鳞茎,在MS＋BA 1 mg/L ＋ NAA 0．1 mg/L培养基上继代可增殖,增殖系数5倍以上;壮苗培养以MS＋BA 0．5 mg/L ＋ NAA 0．1 mg/L 为好;最适生根培养为1/2M S＋IBA 0．5 mg/L ,生根率达90％,;移栽基质以纯沙为最好,成活率达95％以上。     

An alternative modelling approach to predict emissions of N<Subscript>2</Subscript>O and NO from forest soils

Emissions of N₂O from forest soils in Europe are an important source of global greenhouse gas emissions. However, influencing the emission rates by forest management is difficult because the relations and feedbacks between forest and soils are complex. Process-based models covering both vegetation and soil biogeochemical processes are frequently used to analyse emission patterns. Particularly, the simulation of soil C and N turnover processes driving N₂O production, consumption and emission from forest soils requires highly specific input data which renders their regional application difficult since at this scale, soil conditions are often not well understood. Therefore, a soil C and N model (DecoNit) has been developed which describes biogeochemical processes with a simplified structure compared to existing carbon/nitrogen models that nevertheless follows the basic physical and chemical laws involved and which allows to simulate N trace gas emissions. The DecoNit model was previously calibrated using an extensive dataset on decomposition rates of incubated plant materials, microbial dynamics and nitrification. The DecoNit model has now been embedded in a modular simulation environment (MoBiLE) where it is combined with soil water balance and forest process sub-modules. Here, we present the evaluation of MoBiLE-DecoNit with emission data of N₂O and NO from forest soils of 15 European sites and compare simulation results with a previous study in which a more complex model (PnET-N-DNDC) was used. Evaluation criteria were as follows: (1) precision of modelled annual average emission rates; (2) coherence of modelled and measured annual average and daily emissions; (3) a dynamic representation of emission rates that correspond with the observed variance of fluxes. The results show that MoBiLE-DecoNit captures average annual emission rates more precisely than the more complex model PnET-N-DNDC. Also the structural underestimation of N trace gas fluxes from forest soils was resolved. Moreover, we present evidence that the new modelling approach is also somewhat more adequate for describing inter-daily emission dynamics. The combined MoBiLE-DecoNit is therefore thought to be a promising approach to simulate forest development and greenhouse gas balances on site and regional scales.     

Evaluation of quality indexes of bending performance and hardness for hardwoods

The mechanical properties of 613 small clear specimens of 35 species (11 ring-porous hardwoods, 19 diffuse-porous hardwoods, and 5 softwoods) were evaluated. The aim of the study was to examine indexes of wood quality that are easy to measure and that exhibit a high correlation with bending performance and hardness that are essential properties of hardwood products. The modulus of rigidity, dynamic modulus of elasticity, bending properties (modulus of elasticity, modulus of rupture, stress at the proportional limit, absorbed energy, Tetmajer’s modulus), dynamic energy absorption by an impact bending test, compressive strength parallel to the grain, shear strength, partial bearing strength, and Brinell’s hardness were measured. A high correlation was found between dynamic modulus of elasticity and static modulus of elasticity. Bending stress at the proportional limit was found to be approximately equivalent to the compressive strength parallel to the grain. Static energy absorption correlated with dynamic energy absorption. Tetmajer’s modulus was found to be closely related to the ratio of the initial stiffness within the elastic range to the secant modulus at the maximum load. A high correlation was observed between Brinell’s hardness and partial bearing strength. The difference in the regression coefficients obtained for these correlations between the species groups was small. Part of this study was presented at the All Division 5 Conference of IUFRO, Taipei, October 2007     

Applications of wavelet transformation in the nondestructive test of medium density fiberboard

Taking medium density fiberboards (MDF) as samples, the feasibility of the applications of wavelet analysis in a nondestructive test is discussed in this paper. The main results are as follows: the modulus of elasticity of longitudinal resonance, measured by wavelet analysis, can replace the conventional static modulus of elasticity. Their correlation coefficient is significant (p < 0.01). The defect of samples can be judged by wavelet analysis, which is superior because it is a nondestructive test. __________ Translated from Scientia Silvae Sinicae, 2006, 42(10): 91–94 [译自: 林业科学]     

Derivation of tensile strength ratio by second-order theory

Summary Tension members with edge knots or edge knotholes deflect laterally when they are loaded by a tensile force. In order to consider this behavior for determination of tensile strength ratio (TSR), second-order theory is applied. A matrix displacement method of structural analysis developed from the slope deflection method is used to implement the second-order theory. The method reveals that in a member with a single edge knot the lowest TSR is obtained when the lateral deflection is negligible, and when the ends are hinged. For a stiffness value (EI/L) that is small, both end conditions (hinged and fixed) yield the same TSR; for large stiffness value, fixed end condition always gives a higher TSR than a hinged end condition because the moment is reduced at the defect as a result of the fixed ends. The method further reveals that the maximum moment for two edge knots on the same edge is lower than when they are on opposite edges.The findings are important because they can provide guidance in planning tensile testing methods for lumber, in interpretation of results of tests, and in design considerations. These findings help to develop better relationships between TSR, which is an index of tensile strength (T), and apparent modulus of elasticity, E_a, which are so important for the determination of the best predictor of T.Maintained at Madison, Wis., in cooperation with the University of Wisconsin.     

纤维板的静曲弹性模量及静曲强度的动态检测

利用振动无损检测法测得纤维板的动态静曲弹性模量,并用一元和二元回归分析了纤维板的密度、静态静曲弹性模量、动态静曲弹性模量、静曲强度之间的相关性。结果表明:纤维板的静态静曲弹性模量与动态静曲弹性模量之间,或动态静曲弹性模量与静曲强度之间均密切线性相关;以纤维板的动态静曲弹性模量和密度为自变量与静曲强度建立的二元回归方程,其相关程度较一元回归更为密切。密度及长度与横截面面积比值较大的纤维板,其动态静曲弹性模量与静态值较为接近。     

Comparison of fractal characteristics of species richness patterns among different plant taxonomic groups along an altitudinal gradient

This study was done using the non brown fractal model to quantify and compare the variations in the species richness of trees, shrubs, herbs and all plants along an altitudinal gradient and to characterize the dominating ecological processes that determine the variations. Two transects were sampled far away from any anthropogenic disturbances along the shady slopes of the Dongling mountains in Beijing, China. Both transects were continuous and 2 m wide, and every individual tree and shrub was recorded in each of them. Discrete quadrats of 1 m × 1 m were located along the transects A and B for estimation of the herb species richness along the altitudinal gradients. The level interval between the quadrats was 10 m and 25 m respectively. In this study, transects A and B were combined into one transect AB, and 40 m was selected as the optimal quadrat length along the altitudinal gradients for measuring the plant species richness patterns. Species richness in each quadrat was calculated using a program written in Matlab 6.0. Direct gradient analysis was used to describe the overall trends in the species richness of trees, shrubs, herbs and other plants with change in altitude, while the non-brown fractal model was used to detect more accurately their variations at various scales along the gradient. The model assumed that each class of ecological processes affecting the distribution of a variable could be represented by an independent spatial random function. Generally, ecological phenomena are determined not by a single ecological process but by multiple ones. These processes act on ecological patterns within their own spatial scales. In the non-brown fractal model, the spatial random functions are nested within a larger range of spatial scales. The relative contribution of the spatial random functions to the spatial variation of a variable is indicated by a weighting parameter that has to be greater than or equal to zero. In this paper, we reached the following results and conclusions. Firstly, the direct gradient method describes the general trends of trees, shrubs, herbs and all plants along the altitudinal gradient but is unable to provide further details on the altitudinal variations in the species richness. The non-brown fractal model brought out the altitudinal variations in the species richness of trees, shrubs and herbs at various scales and related them to the ecological processes. The sharp changes in the double-log variograms suggest that the non-brown fractal model is suitable for characterizing the altitudinal patterns in the species richness of trees, shrubs and herbs at various scales but is not appropriate for explaining the variations in the plant species richness, since no significant changes were found in the double-log variograms in this case. Secondly, for the trees, the double-log variogram was divided into two scale ranges (0–245 m and 245–570 m), with a fractal dimension of 1.83 and 1.10, respectively, implying that changes in the tree species richness were random at small scales (0–245 m) and almost linear at large scales (245–570 m) along the altitudinal gradients. This suggests that altitudinal variations in the tree species richness are dominated by short-range processes at small scales and by long-range processes at large scales. Thirdly, for shrubs and herbs, the double-log variograms exhibited three ranges (0–101 m, 125–298 m and 325–570 m), and the fractal dimensions were 1.78 and 1.97, 1.56 and 1.43, and 1.08 and 1.25, respectively. The results indicate that, as in the case of trees, species richness of shrubs and herbs are distributed randomly at small scales and change in a linear manner at large scales although variations in the herb species richness is less heterogeneous than shrub species richness at large scales. These results also indicate that species richness of shrubs and herbs change approximately like brown movement at middle scales. The results also suggest that altitudinal variations in the specie richness of shrubs and herbs are dominated by three ecological processes, short-range ecological processes at small scales, long-range ecological processes at large scales, and brown fractal processes at middle scales. Interestingly, comparisons of the variations in the species richness of shrubs and herbs reveal that shrubs and herbs present the same scale range in spatial variation in species richness but display different trends in species richness along the altitudinal gradient, i.e. the shrub species richness decreased with increasing elevation whereas the herb species richness peaked at the mid-high elevation. These patterns suggest that although the scales at which the main processes affect patterns in species richness are the same, the processes are completely different, or the processes are similar but the responses of the shrubs and herbs to the ecological processes are different. Finally, the plant species richness did not show any obvious pattern along the altitude gradient and maintained a constant fractal dimension across all scales, this is perhaps because the processes defining the patterns of plant species richness had similar weights and acted over closely related scales. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(6): 901–909 [译自: 植物生态学报]     

毛竹种群空间格局及分株间关联性——重复空间点格局分析

随着空间调查数据的增多和有重复的空间格局试验设计的需要,重复空间点格局分析方法不断得到研究和应用。采用有重复的空间点格局分析方法研究了不同营林模式下毛竹种群的空间分布格局及其分株间的空间关联性。结果表明：I类经营模式下形成的毛竹种群空间格局呈现随机分布,II类和III类经营模式分别在1.6-2.2 m和0.4-2.6 m尺度上达到了均匀分布的显著水平,表现为随着经营干扰强度的增大,毛竹种群在小尺度（〈3 m）上趋向于均匀分布;在较大尺度（〉4 m）上,3种营林模式毛竹种群空间格局均表现为随机分布;母株与新分株的空间关联性在3种营林模式下较为一致的表现出小尺度上的正关联,并在III类经营模式下,0.6 m、0.8 m和2.2 m尺度上达到了正关联的显著水平,而在较大尺度上,3种营林模式母株与新分株空间格局均表现为无明显的关联性。