[The influence of reference data noise on the NIR prediction results].

This article used hemicelluloses content in acacia spp. wood as a case study to demonstrate the influence of noise in the reference data on the results of NIR calibration model. The results indicated that the accuracy of NIR calibration model was affected by the reference data noise. The less noisy data was used in calibration model, the better result could be obtained. But when the noise was larger, NIR calibration model which was built by using regression mathematics methods can perform better than using primary reference data.

[Preparation and properties of wood/modified UF prepolymer composite materials].

In the present research, the urea-formaldehyde prepolymer and multilayer hot-press drying were used to modify poplar plantation. The prepolymer was impregnated into cell lumen space by pulse-dipping machine. Then the timbers were compressed and dried by the multilayer hot-press drying kiln. The results showed that the physical and chemical properties of poplar were changed in this investigation. The basic density of modified wood increased 1.06 times compared with the natural wood, and the bending strength increased 33% for modified wood, compressive strength parallel to grain increased 74%, the water absorption decreased to 97% from 104%. The crystallinity decreased slightly from 39.65 to 36.89 because of the modifier impregnated. TGA analysis showed that the heat resistance of modified wood increased, the three exothermic peaks in DTA curve of modified wood were 280, 360 and 485 degrees C which were higher than natural wood in the corresponding position FTIR analysis showed that the hydroxyl modified material has a good association phenomenon, and carbonyl content decreased. The SEM spectrum showed the distribution of the prepolymer in the modified timber.

[Preparation and characterization of wood/methylolurea composite with in-situ polymerization].

Wood/methylolurea composite was prepared with the in-situ polymerization. The green timber with high moisture content was impregnated by a pulse-dipping machine and then was dried in a hot-press drying kiln. The cross-linking reaction was taken under the heat treatment between the wood modifier and the wood composition, including cellulose, hemicelluloses, and lignin. The chemical composition was analyzed according to the Chinese standard, including X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) and energy dispersive analysis of X-rays (EDXA). The changes in chemical composition of modified wood and carbon and nitrogen element were disused in the research The results showed that the content of water extraction and benzene alcohol extraction increased 187.43% and 230.87% respectively compared with the natural wood, while the lignin and holocellulose decreased 26.55% and 26.39% respectively. XPS showed that the concentrations of O and C atoms increased 9.4% and N element content increased 137.2%. 13C-NMR analysis showed that chemical reaction of the hydroxyl methyl urea with the hydroxyl in timber structure took place, with the reduction of hydroxyl content and increase in ether bond content. EDXA showed that the processing method can get impregnated modification wood and nitrogen element is evenly distributed in wood cell walls and intercellular space.

[Extending hemicelluloses content calibration of Acacia spp using NIR to new sites].

In this research, hemicellulose contents of 78 wood meal samples of Acacia spp trees grown in Guangxi and another 33 wood meal samples of Acacia spp trees grown in Fujian were measured by wet chemistry. NIR spectra were also collected by a Bruker MPA spectrometer within 4 000-12 500 cm(-1) of wavenumbers using a standard sample cup. Equations were developed using partial least squares (PLS) regression and cross validation for multivariate calibration in this study. High coefficients of determination (R2) and low root mean square errors of cross-validation (RMSECV) were obtained for hemicellulose content (R2 = 0.947, RMSECV = 0.464) of Guangxi woodmeal samples. Prediction produced high correlation coefficients between laboratory and predicted values, with R2 and RMSEP values being 0.925 and 0.455, respectively. A variable numbers of Fujian samples ranging from one to thirteen were used to enhance the Guangxi calibration so as to be widely used for routine assessment of wood chemistry. It was demonstrated that the addition of a single Fujian sample to the Guangxi calibration set was sufficient to greatly reduce predictive errors and that the inclusion of 3 Fujian samples in the Guangxi set was sufficient to give relatively stable predictive errors. The R2 is 0.904 and RMSEP is 0.759. The addition of different sets of 3 Fujian samples to the Guangxi calibration, however, caused predictive errors to vary between sets.

[Application of near infrared spectroscopy in analysis of wood properties].

There is substantial interest in the improvement of wood properties through genetic selection or a change in silviculture prescription. Tree breeding purpose requires measurement of a large number of samples. However, traditional methods of assessing wood properties are both time consuming and destructive, limiting the numbers of samples that can be processed, so new method would be needed to find. Near infrared spectroscopy (NIR) is an advanced spectroscopic tool for nondestructive evaluation of wood and it can quickly, accurately estimate the properties of increment core, solid wood or wood meal. The present paper reviews the advances in the research on the wood chemistry properties and anatomical properties using NIR.