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1.
《Southern Forests》2013,75(2):107-111
Near-infrared spectroscopy has been used to develop calibration models for the rapid determination of kraft pulp yield (KPY) and lignin in Eucalyptus camaldulensis and Leucaena leucocephala. The correlation coefficient for cross-validation is 0.90 for KPY and 0.95 for lignin prediction, while the root mean square error for cross-validation for KPY and lignin prediction are 1.46 and 0.77, respectively. The method has been validated with 37 samples of E. camaldulensis and 18 samples of L. leucocephala. The root mean square error of prediction for KPY (1.53) is higher than for lignin (0.77). The method is rapid and can be used for screening a large number of samples.  相似文献   

2.
《Southern Forests》2013,75(3-4):181-189
Near-infrared (NIR) scanning technology is regarded as a potential tool for rapid determination of wood properties, which can substitute time-consuming and costly traditional methods. Pinus patula is the most important softwood species in South Africa, and this study is aimed at developing NIR calibration models for quick prediction of its pulp yield and chemical composition. A total of 85 trees from 17 plots, covering the range of site conditions in the Mpumalanga escarpment area, were sampled. Two samples were taken from each tree: a 1 m billet above breast height and a 20 mm disc at breast height. The billet was pulped using the kraft pulping process to determine pulp yield. The disc was ground into sawdust and the chemical composition was determined using conventional wet chemistry. Sawdust was scanned on a NIR spectrophotometer to produce NIR spectra. Calibration models to predict pulp yield, cellulose and lignin content were developed by applying chemometrics and partial least squares regression. Validation and determination of prediction accuracy of the models were performed using independent data. The prediction of cellulose and lignin were acceptable with correlations of determinations (r 2) of 0.71 and 0.70 respectively. Standard errors of prediction were generally low (less that 0.86) for all the models. The prediction r 2 for both total and screened pulp yield were only 0.62. Although the cellulose and lignin models can be used with confidence, the expansion of the sample size for follow-up research must be considered in order to increase the variability of tested wood properties and improve the prediction strength of the models. The NIR calibration provided in this study can contribute to the efficient examination of forest site-to-wood quality relationships that would enhance precision forest management and wood processing efficiency.  相似文献   

3.
Feasibility of near-infrared (NIR) spectroscopy for developing multi-species model for plantation timber was explored for estimation of holocellulose in un-extracted milled wood samples. Six commonly planted species of Eucalyptus tereticornis, E. camaldulensis, E. grandis, Leucaena leucocephala, Dalbergia sissoo and Populus deltoides from a wide range of locations and varying age groups were taken for the present study. Few samples of E. hybrid between E. tereticornis and E. camaldulensis were also included in the study to make the model useful for practical application. NIR models were evaluated using partial least squares regression (PLSR-1—full cross-validation, PLSR-2—cross-validation which leaves more than one out) and by dividing the samples into calibration and prediction (test) sets and interchanging them from calibration to prediction sets. The predictive ability of the model was assessed by calculating four ratios of multivariate statistics for individual species model and combined species models. A final combined model for all the species having component range of 76.14–63.03 % and standard deviation of 2.586 % was developed in the spectral range of 7502–4246 cm?1 wave number using 1st derivative plus multiplicative scatter correction using factor of nine by removing samples with outliers found in all the PLSR-2 evaluation steps and in most of the models. The model remained stable even when 30 % of the samples were left out with no outlier detected.  相似文献   

4.
Five Populus x euramericana wood samples representing three different sites were selected and nearinfrared （NIR） spectra were obtained. For these sections, basis weight, brightness and three mechanical properties （tensile index, tearing index and bursting index） were determined by standard analytical methods. Calibrations were developed for each paper property using the NIR spectra, data on paper properties, using partial least squares （PLS） regression. The results show that the coefficients of correlation of calibration and validation for basis weight were 0.8824 and 0.8299, respectively; the standard error of calibration （SEC） and prediction （SEP） were 1.150 and 1.170, respectively. In testing for brightness, the correlation coefficient of calibration was 0.9621 and for validation 0.9612, while the SEC and SEP were 0.997 and 1.300, respectively; paper brightness and NIR spectroscopy were highly correlated. NIR spectroscopy can be used to predict tensile, tearing and bursting indices of paper samples rapidly. We found that the paper properties fitted by NIR and GB methods were highly correlated. The coefficients of correlation of calibration and validation for basis weight exceeded 0.8000, while the SEC and SEP were very small. These results reveal that the five paper properties of Populus x euramericana and those predicted by the NIR model were highly correlated. We conclude that the NIR models can be used for the prediction of paper properties.  相似文献   

5.
The lignin biosynthetic pathway in Eucalyptus camaldulensis was investigated by feeding stems with deuterium-labeled precursor. Pentadeutero[,-D2 OCD3] coniferyl alcohol was synthesized and supplied to shoots of E. camaldulensis, and incorporation of the labeled precursor into lignin was traced by gas chromatography-mass spectrometry. In addition to the direct incorporation of labeled precursor into the guaiacyl unit, a pentadeuterium-labeled syringyl unit was detected. This finding indicates that the -deuterium atoms in the hydroxymethyl group of labeled coniferyl alcohol remain intact during modification of the aromatic ring. The relative level of trideuterium-labeled syringyl monomer (the result of conversion via the cinnamic acid pathway) was negligible, suggesting that the pathway at the monolignol stage is used for conversion of exogenously supplied precursor. Our results provide conclusive evidence of a novel alternative pathway for generation of lignin subunits at the monolignol stage even in plants that do not accumulate coniferin in lignifying tissues.  相似文献   

6.
Within-tree variations of derived wood properties of Runkel ratio, Luces shape factor, slenderness ratio, and solids factor were examined for Eucalyptus camaldulensis and Eucalyptus globulus trees and the tendency difference in the within-tree variations between individuals and between species, in both radial and axial directions by statistical data analysis. These properties are important for quality breeding of pulpwood. In both species, within-tree variations were generally observed as higher values in the upper and outer parts compared with other parts of the trunk for Runkel ratio and Luces shape factor. In E. camaldulensis, within-tree variations were observed as higher values in the upper and outer parts compared with other parts of the trunk for slenderness ratio and solids factor. In E. globulus, within-tree variations were observed as higher values in the outer parts compared with other parts for slenderness ratio and solids factor. However, significant difference of tendency was observed in radial variation between individuals of E. globulus for Runkel ratio and in both radial and axial variations between species for solids factor. Furthermore, within-tree variations of derived wood properties were analyzed to determine a sampling height in the trunk which can be used to represent whole-tree values. Representative heights of derived wood properties from two trees were found to be 2.8m in E. camaldulensis (except for Runkel ratio and Luces shape factor) and 1.8m in E. globules (except for Runkel ratio), regardless of differences in tree height (growth rate) and in tendency of within-tree variation of derived wood properties.  相似文献   

7.
The use of calibrated near infrared (NIR) spectroscopy for predicting the chemical composition of Pinus taeda L. (loblolly pine) wood samples is investigated. Seventeen P. taeda radial strips, representing seven different sites were selected and NIR spectra were obtained from the radial longitudinal face of each strip. The spectra were obtained in 12.5 mm sections from pre-determined positions that represented juvenile wood (close to pith), transition wood (zone between juvenile and mature wood), and mature wood (close to bark). For these sections, cellulose, hemicellulose, lignin (acid soluble and insoluble), arabinan, galactan, glucan, mannan, and xylan contents were determined by standard analytical chemistry methods. Calibrations were developed for each chemical constituent using the NIR spectra, wood chemistry data and partial least squares (PLS) regression. Relationships were variable with the best results being obtained for cellulose, glucan, xylan, mannan, and lignin. Prediction errors were high and may be a consequence of the diverse origins of the samples in the test set. Further research with a larger number of samples is required to determine if prediction errors can be reduced.  相似文献   

8.
The aim of the present work was to estimate the basic wood density of Mimosa tenuiflora by using near-infrared spectroscopy (NIRS). Fifty-eight wood samples representing sapwood, heartwood and pith were evaluated by gravimetric method and NIRS together with wavelength selection methods. A comparison was made among several multivariate calibration techniques and algorithms for preprocessing and variable selection of data, including full-spectrum partial least squares (PLS), interval PLS, backward interval PLS, synergy interval PLS, genetic algorithm-PLS and successive projections algorithm for interval partial least squares (iSPA–PLS). Finally, the results obtained using iSPA–PLS model for the root mean square error of calibration and prediction were 0.0383 and 0.0166 g/cm3, respectively. A t-test was performed to compare the results of the models with each other and with a reference method. NIRS and iSPA–PLS can be used to predict basic density of Mimosa tenuiflora [Willd.] Poiret wood samples rapidly. In addition, the basic density could also be predicted with only 17 wavelengths in the range from 2,090 to 2,208 nm that should allow for measurement of this parameter using handheld NIR spectrometer.  相似文献   

9.
A trial set-up with methods for sampling, treatment and analysis of small wood chips are presented in this paper, to determine important wood and fibre properties, like basic density, dry density, volume swelling of wood, Kraft pulp yield, fibre length, fibre coarseness, fibre width, lumen width and fibre wall thickness. The required time for one sample is about 1.5 man-hour, but this requires relatively larger series and trained personnel. Acceptable measurement accuracy is achieved when the volume of the wood sample is at least 1.5 ml, except that of wood volume swelling. To gain acceptable measurement accuracy for volume swelling, the wood volume should be increased to at least 3 ml, and preferably more than 5–6 ml per sample. The level of pulp yield and wood density do not show a significant effect on the measurement accuracy for fibre cross-section dimensions. Fibre coarseness, on the other hand, has a significant influence on these accuracies. A double measurement of fibre coarseness will improve the accuracy to an acceptable level. The method presented here may, together with information about trees and growth locations, form the basis for greater insight into the mechanisms involved in development of wood and fibre properties in trees, which in turn may provide better control and utilisation of wood for pulp and paper production.Abbreviations CWD cell wall density in dry wood=1500 kg/m3 - Ww dry weight of wood (kg) - Vmax green (wet) volume of wood (m3) - Vmin dry volume of wood (m3) - BD basic wood density (kg/m3) - DD dry wood density (kg/m3) - VS maximum volume swelling of wood (%) - Wp dry weight of pulp (kg) - PY pulp yield (%) - C fibre coarseness, the average weight of a unit length of fibre (g/m) - CL average chip length (mm) - CWT average cell wall thickness (m) - FW average fibre width (m) - l average native fibre length in solid wood - L chip length - lc average fibre length in wood chip (mm) - Lc length-weighted fibre length in wood chip (mm) - lw native average fibre length in wood (mm) - Lw native length-weighted fibre length in wood (mm) - LW average lumen width (m) - llw average native fibre length, length weighted, in wood - X average fibre length in chip - Xlw average fibre length, length weighted, in chip  相似文献   

10.
 Relationships between cell and pulp properties were investigated by examining the within-tree property variations in Eucalyptus camaldulensis and Eucalyptus globulus. Properties investigated included proportions of ray and axial parenchyma, thickness of cell walls and cell wall percentages. The characteristics of the ray and axial parenchyma (their proportions and wall thickness) were found to have a significant influence on all measured pulp properties, including paper strength properties. Multiple regression of pulp properties in relation to cell properties revealed that nearly all measured pulp properties were explained by cell properties at the 1% significance level. It was concluded, therefore, that all cell types are important for predicting pulp properties, and it is strongly recommended that tree breeding programs for Eucalyptus include the measurement of all cell types. Received 6 July 1999  相似文献   

11.
  • ? Methods based on near infrared spectroscopy used to assess wood properties are susceptible to variations in physical parameters (temperature, grain size, etc.). As wood is a hygroscopically sensitive material, we studied the effects of moisture on near infrared absorbance and calibration to accurately determine the application potential of this technique under routine.
  • ? A collection of Eucalyptus urophylla × E. grandis hybrid wood pieces were analysed to obtain reference calibration of polyphenol contents in wood extracts via NIR spectra acquired under constant moisture conditions. Other specimens from the same source were assessed to obtain spectra for eight moisture contents spanning a broad variation range. The effects of moisture on absorption and on estimates based on a reference model were analysed.
  • ? An increase in moisture content prompted a rise in near infrared absorption over the entire spectrum and for water O-H absorption bands. The polyphenol content estimates obtained by assessing specimens against the reference calibration at variable moisture contents revealed prediction bias. Five correction methods were then tested to enhance the robustness relative to moisture.
  • ? In-depth calibration and external parameter orthogonalization (EPO) were found to be the most efficient methods for offsetting this factor.
    •   相似文献   

    12.
    Crystallinity is an important property of woody materials; it responds to tree growth traits, structure, and chemical composition, and has a significant effect on Young’s modulus, dimensional stability, density, and hardness, etc. The ability of near-infrared (NIR) spectroscopy coupled with multivariate analysis to rapidly predict the crystallinity of slash pine (Pinus elliotii) plantation wood was investigated. The results showed that the NIR data could be correlated with the X-ray diffraction (XRD)-determined crystallinity of slash pine wood by use of partial least squares (PLS) regression, producing excellent coefficients of determination, r 2, and root mean square error of calibration, RMSEC. The use of either reduced spectral ranges or the selection of certain wavelengths consistent with known chemical absorptions did not have any detrimental effect on the quality of PLS models allowing the use of inexpensive, small, and portable spectrometers. These studies show that NIR spectroscopy can be used to rapidly predict the crystallinity of slash pine wood.  相似文献   

    13.
    Summary The kinetics of HCl-catalysed delignification of Eucalyptus globulus wood by 70% (w/w) acetic acid solution were satisfactorily explained by a model in which 5% of the lignin fraction could not be eliminated and the remaining 95% was eliminated by a single process which, in view of the activation energy calculated from the data was attributed to the hydrolysis of -aryl ether bonds. The selectivity of the process was effectively independent of HCl concentration and operating temperature for pulp yields >50%. At high temperature (160 °C) and catalyst concentration (0.027 MHCl), lignin condensation and precipitation became significant and the data were better fitted by a model comprising two consecutive processes: lignin solubilization followed by lignin condensation.The authors are grateful to the CICYT for financial support of this work (Project AGF93-0605) and also to the DGICYT for a research grant awarded to J. González  相似文献   

    14.
    Determination of quality parameters such as lignin and extractive content of wood samples by wet chemistry analyses takes a long time. Near-infrared (NIR) spectroscopy coupled with multivariate calibration offers a fast and nondestructive alternative to obtain reliable results. However, due to the complexity of the NIR spectra, some wavelength selection is generally required to improve the predictive ability of multivariate calibration methods. Pinus brutia Ten. is the most growing pine species in Turkey. Its rotation period is around 80 years; the forest products industry has widely accepted the use of Pinus brutia Ten. because of its ability to grow on a wide range of sites and its suitability to produce desirable products. Pinus brutia Ten. is widely used in construction, window door panel, floor covering, etc. Determination of lignin and extractive content of wood provides information to tree breeders on when to cut and how much chemicals are needed for the pulping and bleaching process. In this study, 58 samples of Pinus brutia Ten. trees were collected in Isparta region of Turkey, and their lignin and extractive content were determined with standard reference (TAPPI) methods. Then, the same samples were scanned with near-infrared spectrometer between 1,000 and 2,500 nm in diffuse reflectance mode, and multivariate calibration models were built with genetic inverse least squares method for both lignin and extractive content using the concentration information obtained from wet standard reference method. Overall, standard error of calibration (SEC) and standard error of prediction (SEP) ranged between 0.35% (w/w) and 2.40% (w/w).  相似文献   

    15.
    We propose a non-destructive method to predict the oven-dry density of Sugi (Cryptomeria japonica D. Don) using near infrared (NIR) spectroscopy so as to calibrate a commercial moisture meter. A prediction model for oven-dry density was developed using NIR spectra obtained from Sugi samples with a known density. The density of air-dried Sugi boards was predicted with the developed model. Then, the moisture content (MC) of the boards was measured by a hand-held capacitance-type and an in-line microwave moisture meters. For each board, the moisture meters were calibrated by the predicted density. The predicted density was correlated with the measured one with an R 2 of 0.81 and a standard error of prediction (SEP) of 15.3 kg/m3 within the measured density of 279.2–436.4 kg/m3, indicating that the developed model was applicable for predicting oven-dry density of Sugi. The MC readings of both moisture meters showed a good correlation with the oven-dry MC that ranged from 12.1 to 28.9 %. For both moisture meters, the density calibration with the NIR-predicted density gave a higher R 2 and a lower SEP than with the conventional calibration with the mean density. These results demonstrate that the present density calibration using NIR spectroscopy could improve the performance of the moisture meters for the air-dried Sugi boards with varying densities.  相似文献   

    16.
    《Southern Forests》2013,75(2):155-164
    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.  相似文献   

    17.
    To determine the independent decomposition rates of lignin and cellulose of decayed woody debris, a technique for the rapid analysis of lignin and cellulose is required. We applied a near-infrared spectroscopy (NIRS) technique to measure the lignin and holocellulose content in decayed wood. We succeeded in creating partial least-squares (PLS) models to estimate the lignin and holocellulose content in the decayed wood of five species using NIR spectra. Although the accuracy was acceptable for the estimation of a five-species mixed model (R 2 = 0.970 for lignin and R 2 = 0.962 for holocellulose), it was further improved when the model was applied to each species independently. This combination of NIRS and a PLS model is a valuable tool for the determination of the lignin and holocellulose content in decayed wood. The technique is time efficient (3 min per sample) and non-hazardous (no acid treatment is required).  相似文献   

    18.
    Tropical provenances of Eucalyptus camaldulensis Dehnh. and E. tereticornis Smith were studied, in their natural habitat in Australia and in a 3.75-year-old progeny trial in Zimbabwe, for their potential to produce medicinal-grade essential oils. Substantial interand intra-specific variation in the contents of five prominent monoterpenes, 1,8-cineole, -pinene, -pinene, limonene and p-cymene was found. Plantations of E. camaldulensis established in the wet/dry tropics using seed from Petford in northern Queensland offer immediate potential for oil production. Other widely-planted Queensland provenances with oil potential are Gilbert River Bridge E. camaldulensis and, after some genetic improvement, E. tereticonis from Morehead and Kennedy Rivers. Select individual trees at Petford provide oil of enhanced quality, at about double the yield of average trees.  相似文献   

    19.
    用常规方法测定了104个速生桉木样品的综纤维素、聚戊糖、酸不溶木素及苯醇抽出物含量并采集了样品的近红外光谱。对原始光谱进行多元散射校正后,运用偏最小二乘法和交互验证的方法,确定最佳主成分数并建立样品相关化学成分含量的校正模型。独立验证中综纤维素、聚戊糖、酸不溶木素和苯醇抽出物模型的决定系数 Rval2分别为0.9067、0.9033、0.9504、0.9570;预测均方根误差(RMSEP)分别为0.33%、0.50%、0.31%、0.17%;相对分析误差(RPD)值分别为3.22、3.20、4.43、4.73;绝对偏差(AD)分别为?0.53%~0.60%、?0.95%~0.77%、?0.55%~0.52%、?0.22%~0.29%,4个校正模型较好地预测了验证集样品的化学成分含量,基本满足制浆造纸工业中快速测定速生桉木原料的需求。  相似文献   

    20.
    Summary The purpose of this study was to determine the progressive changes in physical and chemical properties of Eucalyptus globulus wood under the action of a representative white rot fungus, Coriolus versicolor. Observations concerning the nature and relative effects on weight loss, hot water solubility, 1% sodium hydroxide solubility, Klason lignin, holocellulose, intrinsic viscosity and degree of polymerisation of holocellulose, pentosans, methoxyl value, neutral sugar composition and nitrobenzene oxidation products are discussed.The authors thank Dr. P. S. Rehill, the then Officer-in-Charge, Forest Pathology Branch, for valuable suggestions and providing facilities for decay experiments  相似文献   

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