Commercial Wood Research Articles

Heat Transfer Efficiency and pMDI Curing Behavior during Hot-Pressing Process of Tea Oil Camellia (Camellia Oleifera Abel.) Shell Particleboard.

The use of agricultural biomass composites as new construction and building materials has grown rapidly in recent decades. Considering that energy consumption is one of the most important factors in production, the aim of this work is to examine how heat transfer is affected at various ratios and combinations of three-layer tea oil camellia shell (TOCS) based particleboard with the purpose of creating a mat-forming structure, which has the best physical and mechanical properties for furniture and construction use in a dry environment and consumes the least amount of energy. Additionally, it investigated how raw materials type affects the curing process of polymeric methylene diisocyanate (pMDI) using differential scanning calorimetry (DSC). According to the obtained data, the centerline temperature could reach a maximum of 125 °C after 3 min regardless of the materials or combinations, while the pMDI curing time was 100-110 °C. The results demonstrated that efficient heat transfer could help resin polymerization and improve panel properties. The effect of raw materials on the curing behavior of resin indicated that TOCS particles somehow caused more heat reactions at the curing point. It appeared that particleboard with a ratio of 40% commercial wood particles in the surface layers and 50% TOCS particles (mesh size: -3 + 14) in the core layer with a modulus of rupture (MOR) of 11.29 N/mm2 and internal bonding (IB) of 0.78 N/mm2 has the best properties and met EN 312: 2010 standard requirements for particleboard P2.

The flexural properties of oil palm trunk (OPT) impregnated with epoxy (OPTE) composite manufactured by vacuum-assisted resin transfer moulding (VARTM) technique

Nowadays, the utilization of oil palm trunk (OPT) biomass has gained more interest in composite applications. This research presents the flexural properties of unimpregnated OPT and OPT impregnated with epoxy (OPTE) composites. The OPTE composites were fabricated using the vacuum-assisted resin transfer moulding (VARTM) technique. The unimpregnated OPT and OPTE composite specimens were selected from three different zones of longitudinal zone OPT namely Zone I (outer), Zone II (middle) and Zone III (inner), respectively. The flexural test was conducted according to ASTM D790. The results showed promising increases in flexural strength and flexural modulus of the OPTE composite in Zones I, II, and III compared to unimpregnated specimens, with increases of 254.09 % (49.79 MPa) and 158.78 % (4.14 GPa) in Zone I, 297.43 % (37.28 MPa) and 309.51 % (3.58 GPa) in Zone II, and 242.67 % (29.34 MPa) and 305.84 % (2.94 GPa) in Zone III, respectively. There was positive trend linear regression significantly observed in the relationship between flexural strength and modulus of elasticity (MOE) of OPTE composites and unimpregnated OPT of all three zones, respectively. The fractured flexural specimens of three different zones were analysed by using scanning electron microscopy (SEM). The improvement of OPTE composites is a possible as an alternative to replace the existence of commercial wood.

Textile handicraft for equipment-free fabrication of wearable low-cost diagnostic sensors for body-fluid based pathology

We report a low-cost, rapid and single-step method for fabricating microfluidic cloth-based analytical devices (μCADs) without involving any sophisticated instruments, simply by painting hydrophobic zones on cotton cloth using a liquid mixture primarily composed of polyurethane-based commercial wood finish. The mixture needs to be applied on cloth using a paint brush and subsequently dried in open air for only around 5 min to complete the process of hydrophobic barrier deposition. The painted regions show extreme hydrophobicity and demonstrate excellent barrier integrity and chemical inertness with a wide range of liquids, reagents, solvents and biological fluids. Channels of different designs are fabricated with sufficient dimensional reproducibility, despite adhering to manual painting step. Using this simple fabrication method, a colorimetric glucose detection assay is demonstrated on cloth-based devices, which has been found to be highly accurate as benchmarked with a laboratory-referenced biochemistry analyzer. The inherent simplicity and cost-effectiveness of this method is likely to foster sustainable growth of rural handicrafts specialized in manufacturing low-cost wearable sensors for rapid point-of-care diagnostics.

Investigation of NIR spectroscopy and electrical resistance-based approaches for moisture determination of logging residues and sweet sorghum

Techniques based on electrical resistance and near-infrared (NIR) spectroscopy were used to determine the moisture content (MC) of logging residues and sweet sorghum. The MC of biomass is a factor to be controlled that can affect the quality of final products. To accurately measure the moisture in fragmented materials, it is essential to increase the bulk density of the materials by compression. The low bulk density increased the error from the oven-drying MC and the variation between repeated measurements. The calculated correction factor made it possible to use a commercial wood moisture meter for biomass materials. Ordinary least squares regression models built with the electrical resistance data achieved coefficients of determination (R2) of 0.933 and 0.833 with root mean square errors (RMSE) of 0.505 and 0.891, respectively, for the MC predictions of logging residue and sweet sorghum. Partial least squares regression models combined with NIR spectroscopy achieved R2 of 0.942 and 0.958 with RMSE of 1.318 and 3.681 for logging residue and sweet sorghum, respectively. In contrast to the electrical resistance-based models, the NIR-based models could predict the MC regardless of the bulk density of the materials. Data transformation by the second derivative and removal of outliers contributed to the improvement of the prediction of the NIR-based models.

Comparison of DNA extraction methods on CITES-listed timber species and application in species authentication of commercial products using DNA barcoding

Quality and quantity of DNA extracted from wood is important for molecular identification of wood species, which can serve for conservation of wood species and law enforcement to combat illegal wood trading. Rosewood (Dalbergia and Pterocarpus) and agarwood (Aquilaria) are the most commonly found hardwood in timber seizure incidents. To monitor international trade of timber and commercial wood products and to protect these endangered wood species from further population decline, in this study, we have compared three extraction protocols for DNA extraction from 12 samples of rosewood and agarwood timber logs, and later applied the best DNA extraction protocol on 10 commercial wood products claimed to be rosewood and agarwood. We also demonstrated the applicability of DNA mini-barcoding with multi-loci combination with reference library for identifying the species of timber and commercial wood products. We found that a silica column-based method with guanidine thiocyanate-containing binding buffer served the best in DNA extraction from different parts of wood in all three genera with good quality and quantity. Single barcode region ITS2 or multi-loci combinations including ITS2 barcode region generally provide better discriminatory power for species identification for both rosewood and agarwood. All 10 products were identified to species-level using multi-loci combination. In terms of accuracy in labelling, 80% of them were labelled correctly. Our work has shown the feasibility of extracting good quality of DNA from authentic wood samples and processed wood products and identifying them to species level based on DNA barcoding technology.

Effect of isocyanate index on shear strength plywood properties using Acacia mangium polyurethane-based adhesive

Polyurethane adhesive for wood bonding were prepared from the mixture of Acacia mangium (AM) polyol and 4,4’-methylene diphenyl diisocynate (pMDI). In this study, Acacia mangium polyurethane (AMPU) adhesives were prepared by polymerization between pMDI and AM polyol. Various NCO/OH ratios of AMPU adhesives were used to fabricate 3-ply plywood from Eucalyptus wyrai veneers. The effect of different NCO/OH ratios: 1:4, 1:6, 1:8, 2:0, 2:2, 2:4 and 2:6 on lap shear strength and chemical resistance in cold water, hot water, sulfuric acid solution (pH2) and sodium hydroxide solution (pH12) were studied. The commercial PU adhesives were used for comparison purposes. The results show that PU adhesives prepared from pMDI with AM polyol with NCO/OH ratio at 2.4 have higher lap shear strength and chemical resistance by only showing slight degradation (2-8%) compared to commercial PU wood bonding adhesive.

Small wood pellet boiler 3-D CFD study for improved flue gas emissions employing flue gas recirculation and air staging

Wood biomass fuels have become increasingly important in terms of achieving future sustainability targets regarding RES, especially to reduce GHG and the use of domestic energy sources, on other hand with these fuels the pulutant air emissions have to be addressed with great attention. Nowadays, air staging and flue gas recirculation are often used as a primary emission reduction measure in large scale biomass fuel fired boilers, but their combined application in small scale commercial wood pellet boilers is not so common. The implementation of this approach to the small scale burning devices can enable further development of small boilers, in order to achieve a more complete combustion and reduction of pollutant emissions, especially CO, NOx, and PM. In the presented work a comprehensive numerical and experimental study on the combustion parameters is performed, in order to determine the overall combustion properties. A commercial 32 kW small-scale hot water wood pellet boiler was modified numerically from the operating point of view. The findings of this study, like different combinations of recirculated flue gases and secondary air amount, can serve as useful guidelines for the new innovative design and optimisation of the air and recirculated flue gas injection process parameters. The scenarios of this study, where recirculated flue gas was added to the secondary air, were beneficial. Optimally, a CO reduction of 63% was achieved by adding 30% of recirculated flue gas to the secondary air stream, and a 22% reduction was achieved for the NO emissions.

Effects of Nanosilver and Heat Treatment on the Pull-Off Strength of Sealer-Clear Finish in Solid Wood Species.

Pull-off strength is an important property of solid wood, influencing the quality of paints and finishes in the modern furniture industry, as well as in historical furniture and for preservation and restoration of heritage objects. The thermal modification and heat treatment of solid wood have been the most used commercial wood modification techniques over the past decades globally. The effects of heat treatment at two mild temperatures (145 and 185 °C) on the pull-off strength of three common solid wood species, i.e., common beech (Fagus sylvatica L.), black poplar (Populus nigra L.), and silver fir (Abies alba Mill.), were studied in the present research work. The specimens were coated with an unpigmented sealer-clear finish based on an organic solvent. The results demonstrated a positive correlation between the density and pull-off strength in the solid wood species. Heat treatment at 145 °C resulted in an increase in the pull-off strength in all three species, due to the formation of new bonds in the cell-wall polymers. Thermal degradation of the polymers at 185 °C weakened the positive effect of the formation of new bonds, resulting in a largely unchanged pull-off strength in comparison with the control specimens. Impregnation with a silver nano-suspension decreased the pull-off strength in beech specimens. It was concluded that density is the decisive factor in determining the pull-off strength, having a significant positive correlation (R-squared value of 0.89). Heat treatment at lower temperatures is recommended, to increase pull-off strength. Higher temperatures can have a decreasing effect on pull-off strength, due to the thermal degradation of cell-wall polymers.

Comparing the Building Code Sawn Lumber’s Wet Service Factors (CM) with Four Commercial Wood Species Laboratory Tests

Indonesian Wooden Building Code (SNI 7973-2013) has adopted the National Design Specification (NDS) for Wood Construction since 2013. A periodic harmonization of the building-code-designated values (i.e., reference design values and adjustment factors) with the experimental data of commercial wood species is necessary. This study aimed to compare the building code’s wet service factors (CM) with the laboratory test of some commercial wood species. Since wood is weaker when its moisture content is high, the wet service factor (CM) must adjust the sawn lumber reference design values if the building serves in wet or aquatic environments. Four commercial wood species, namely pine (Pinus merkusii), agathis (Agathis dammara), red meranti (Shorea leprosula), and mahogany (Swietenia mahagoni), were subjected to mechanical property tests. To calculate the empirical CM values, the mechanical properties tests were conducted on air-dry and wet wood. Instead of testing the full-sized timber, which contains the growth characteristics and defects, this study chose clear-wood specimens to resemble the boundary condition of the ceteris paribus (other things being equal). The wet (water-saturated) specimens were immersed in water for 65 days, and the test was carried out when the specimen was still immersed. The test arrangement imitated the submerged wood as the worst-case scenario of the wet environment where the construction serves, rather than green or partially immersed timber. As many as 40 specimens were tested to compare each mechanical property’s wet service factor; thus, this study reported 200 specimens’ laboratory test results. The empirical CM values to adjust the modulus of elasticity, modulus of rupture, shear strength parallel-to-grain, tensile strength parallel-to-grain, and maximum crushing strength (CM = 0.59, 0.76, 0.65, 0.73, and 0.67, respectively) were significantly lower than SNI 7973-2013 designated values (CM = 0.9, 0.85, 0.97, 1, and 0.8, respectively). The empirical CM for the compression stress perpendicular-to-grain at the proportional limit and that at the 0.04″ deformation (CM = 0.66) were slightly lower than the designated values (CM = 0.67), although they were not significantly different. This study resulted in lower empirical CM values than the designated ones, which found that the building code lacked conservativeness. The lacked conservativeness is mainly attributed to the building code’s recent choices, e.g., (1) the wet service environment basis is the green timber rather than the fully water-saturated one, and (2) the ratio of near minimum (5% lower) distribution value is chosen as the CM value rather than the average of wet timber’s mechanical property divided by the air-dry one. This study proposes changing both recent choices to alternative ones to develop more safe and reliable designated CM values.

Pemanfaatan Limbah Penggergajian Kayu Meranti Merah Sebagai Bahan Baku Papan Partikel Kerapatan Sedang Dengan Perekat Alami Asam Sitrat

Red Meranti was a commercial wood that is widely used as a raw material for the timber industry (plywood and sawmill industry), and generated a lot of waste. Currently, the utilization of red meranti waste has not been utilized optimally. One of the optimizing utilization of that waste was for developing a Particleboard with the citric acid natural binder. The objective of this study was to determine the bonding properties of Sawmill Waste Red Meranti Particleboard bonded with a Citric Acid Natural Adhesive. Citric acid was dissolved in water with the concentration of the solution adjusted to 60 wt%. This adhesive solution was sprayed onto the 40 mesh (coarse) and 40 mesh (fine) particles at 10% and 20% resin content based on the weight of oven-dried particles. Each mixture was then hot pressed at 110°C for 15 min under 50 kg/cm² pressure. Density and dimension targets were 0.7 kg/cm³; 30 × 30 × 1 cm. Each experiment was performed in triplicate, and the average value and standard deviation were calculated. The results showed that the interaction of particle size and adhesive content had a very significant effect on density, internal bonding, and screw-holding strength and had no significant effect on moisture content, thickness swelling, and modulus of rupture (MOR). Based on the SNI 03-2105-2006, the physical properties that meet the standard were moisture content and. Meanwhile, the mechanical properties of sawmill waste red meranti particleboard have not met the SNI 03-2105-2006.
 Kata kunci (Keywords): Sawmill waste, red meranti waste, citric acid, natural binder.

Improvement effects of treating with calcined oyster shell and carbonized cow dung compost on clay with high water content

Effective waste treatment as a new binder apply to improve soft clay is an economical and environmental solution for stabilizing soft clay. In this context, this study proposes a high-water content clay improvement case using calcined waste oyster shells (COS) and carbonized cow dung compost (CC) as substitutes for cement to stabilize clay with high-water content. In this study, the solidifying agent/water ratio, C/(w/100), was introduced as an important parameter to evaluate the improvement effect of COS stabilized clay. Compared with ordinary Portland cement (OPC), the mixed amount of COS required for effective improvement is significantly reduced (≈43–46 %). In addition, the incorporation of more environmentally friendly carbonation materials improves the improvement effect of COS stabilized clay. A comparison with commercial wood charcoal proved that CC with better adsorption capacity significantly improved high-water-content clay. The test results of energy-dispersive X-ray spectrometry (EDS) and scanning electron microscope (SEM) show that with an increase in COS content, the reaction product hydrated calcium silicate is formed, and the improvement effect of stabilized clay is enhanced. In addition, the incorporation of water-absorbent materials reduced the void space in the clay structure, which is conducive to stabilizing the internal cementation of clay. SEM evidenced the change of microstructure of the stabilized clay owing to the gel materials.

Leaf-transcriptome profiles of phoebe bournei provide insights into temporal drought stress responses.

Phoebe bournei (Hemsl.) Yang is used as a commercial wood in China and is enlisted as a near-threatened species. Prolonged droughts pose a serious threat to young seedlings (1-2 years old). A transcriptome sequencing approach, together with the measurement of growth parameters and biochemical analyses were used to understand P. bournei's drought responses on 15d, 30d, and 45d of drought stress treatment. The stem and root dry weights decreased significantly with drought stress duration. Activities of antioxidative enzymes i.e., peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) increased significantly with the increase in drought stress duration. A total of 13,274, 15,648, and 9,949 genes were differentially expressed in CKvs15d, CKvs30d, and CKvs45d, respectively. The differential expression analyses showed that photosystem I and II underwent structural changes, chlorophyll biosynthesis, and photosynthesis were reduced. The genes annotated as POD, SOD, and CAT were upregulated in drought-treated leaves as compared to control. Additionally, plant-hormone signal transduction, MAPK signaling-plant, phenylpropanoid biosynthesis, flavonoid biosynthesis, and starch and sucrose metabolism pathways showed large-scale expression changes in major genes. We also found that members of 25 transcription factor families were differentially expressed. Our study presents and discusses these transcriptome signatures. Overall, our findings represent key data for breeding towards drought stress tolerance in P. bournei.

Моделирование критических локальных деформаций коры растущего дерева при ветровой нагрузке

The interaction between wind loads and forest plantations has been fairly well understood. A large amount of valuable scientific and practical information has been obtained and published so far in this field. There are some known data on wind load damage to plantations, its effect on their growth, and the ability of forest plantations to reduce wind speed and force. Nevertheless, the issues of wind impact on both individual trees and forested areas remain relevant. Analysis of the literature and Internet resources showed that the research has left out the issue of the wind load impact on the grown wood quality. Multi-year observations and a wind rose created using these observations enable the determination of the prevailing wind strength and direction for each area. Knowing the features of the wind load impact on the quality of timber after logging, it is possible to predict the percentage of the yield of commercial and low-quality wood, and to purposefully influence this parameter in plantation forest growing by setting out the planting material in accordance with these data. The article shows the developed method for theoretical estimation of the probability of occurrence of critical bark deformations in the compressed zone, which appears when bending a growing tree due to wind load. Classical studies of the critical state of compressed rods on an elastic base were used as the theoretical basis of the method. A part of growing tree bark plays the role of a rod, while cambium and other living cells between the bark and the trunk wood play the role of the elastic base. A correlation simple enough for practical application is proposed in order to obtain quantitative estimates. Adequacy of the modeling results is confirmed by their consistency with the experimental data. The application of the developed methodology is shown on the examples.

Variation in Growth, Wood Basic Density and Fiber Characters in Selected Clones of Acacia auriculiformis A. Cunn. Ex benth

The study aimed to screen and shortlist superior Acacia auriculiformis clones for desirable growth and wood properties. Twenty clones stem volume, wood basic density and fibre characters were studied at age of four. Significant variations were recorded in tree volume and wood properties among the clones, the stem volume of the clones was ranging from 0.022 to 0.073 m3 and the maximum tree volume was noticed in clones IFGTBAA 7 and followed by IFGTBAA 27 and 18, the studied clones average stem volume was 0.039 m3. The average wood basic density of the clones was 469 kg/m3 and this trait was ranging from 406 to 509 kg/m3. The screened A. auriculiormis clones average fibre length was ranging from 785.4 µm to 1140.6 µm and a maximum fibre length above 1000 µm was recorded in clones IFGTBAA 18, 23, 26 and 62. The average Runkel Ratio of all the clones was 0.91 and it was ranging from 0.7 to 1.1. There was no significant positive correlation noticed between growth, wood basic density and fibre properties except stem volume and fibre lumen diameter. Hence, it was decided to select superior clones, IFGTB 7,18,20,23 and 27 based on combined traits of Stem Volume, Wood Basic Density and Fibre Length to establish large scale commercial pulp wood plantations and clones which were having higher density and fibre properties had scope to utilize as parents in A. auriculiformis improvement programme to enhance tree volume and wood quality.

Indonesian Commercial Woods Classification Based on GLCM and K-Nearest Neighbor

Currently, the presence of wood is becoming increasingly scarce. In addition, the recognition of wood is still using wood experts, who basing their judgments on the characteristics that can be seen by eye directly such as color, texture and so on. However, wood experts are still few and have a disadvantage that the results obtained are still not sufficiently accurate and time consuming. The purpose of this research is to develop Indonesian commercial woods classification system based on GLCM and k-Nearest Neighbor. Procedures of the wood classification system includes image acquisition using a digital camera, then a preprocessing steps by converting the original image to grayscale image and sharpening the image, after that do texture feature extraction using Gray Level Cooccurrence Matrix (GLCM) with the parameters used are Contrast, Correlation , Energy, Entropy, and Homogeneity, at each direction that are 0°, 45°, 90°, 135°,and the last step is the classification using the k-Nearest Neighbor (k-NN). The testing results show that the testing data can be classified accurately 100% is a testing data derived from the training database with k = 1. In general, the greater the value of k then the classification success rate decreases.

Accelerated swelling of wood for rapid dimensional stability

Dimensional stability of wood can be determined by measuring the total swelling percentage between 0% and FSP moisture content according to the ABNT NBR 7190 (Associação Brasileira de Normas Técnicas [ABNT], 1997). Wood dimensional variation by the moisture content modifications must influence both structural elements and connections into timber structures. The wood swelling procedure according to the Brazilian code for saturation of wood samples can take more than a month, but the use of autoclave devices may accelerate this activity, making easier the dimensional stability determination. This paper aims to investigate the possibility of accelerating the wood swelling activity using an autoclave device, considering the Brazilian code for thirteen Brazilian commercial wood species. Contrast test for comparison between accelerated process (Stage 4 – 225 min. at 0.49 MPa pressure) and the conventional procedure for wood swelling resulted in p-value equal to 0.0730 and the average difference between groups about 1.1307% (varying between -0.0541 and 2.3156 with 95% confidence level). According to results, 225 min. at 0.49 MPa pressure provides an equivalent wood swelling compared to the conventional procedure, which can make faster the wood dimensional stability evaluation according to the ABNT NBR 7190 (ABNT, 1997).

Environment-friendly cornstarch and tannin-based wood adhesives for interior particleboard production as an alternative to formaldehyde-based wood adhesives

PurposeIn industrial applications, formaldehyde-based wood adhesives have been used extensively because of their low costs and high reactivity. However, their real-world applications are hindered by some main bottlenecks, especially the formaldehyde emission and usage of nonrenewable raw materials. The purpose of this study is the development of sustainable and formaldehyde-free wood adhesive formulation.Design/methodology/approachIn this study, starch and tannin-based wood adhesive were synthesized. Chemical structures and thermal properties of the prepared bio-based resin formulations were elucidated by using Fourier transform infrared and differential scanning calorimetry analysis, respectively. Laboratory scale particleboard production was carried out to determine the performance of the developed resin formulations. Obtained results were evaluated in dry medium (P2) according to European norms EN 312 (2010). Furthermore, the board formaldehyde content was determined by using the perforator method according to the European Norm EN 12460-5.FindingsThe results show that the improved starch and tannin-based wood adhesives were successful in their adhesive capacity, and the formaldehyde content of the final product was obtained as low as 0.75 mg/100 g. This paper highlights that the presented adhesive formulations could be a potential eco-friendly and cost-effective alternative to the formaldehyde-based wood adhesives for interior particleboard production.Research limitations/implicationsStarch-based resins in the liquid form needed to be continuously mixed throughout their shelf life to prevent the starch from settling because it was not possible to dissolve the precipitated starch again after a while. For this reason, starch was given to the chips in powder form while preparing the particleboard.Practical implicationsIn conclusion, this study shows that the developed bio-based resin formulations have a high potential to be used for producing interior-grade particleboards instead of commercial formaldehyde-based wood adhesives because the obtained results generally satisfied the interior grade particleboard requirements according to European norms EN 312, P2 class (2010). In addition, it was determined that the produced boards had significantly low formaldehyde content. The low formaldehyde content of the final boards was not because of the resin but because of the natural structure of the wood raw material, press parameters and environmental factors.Social implicationsThe developed bio-based resin system made it possible to obtain boards with significantly low formaldehyde content compared to commercial resins.Originality/valueThe developed bio-based resin formulation made it possible to produce laboratory-scale board prototypes at lower press factors and board densities compared to their counterparts.

Acoustic and Thermal Properties of Particleboards Made from Mulberry Wood (Morus alba L.) Pruning Residues

The aim of this study was to determine the acoustic and thermal properties of particleboards made from mulberry wood pruning waste using urea formaldehyde resin (UF) as a binder. The investigation focused on the evaluation of the thermal conductivity and the acoustic absorption of the boards and the assessment of their feasibility for use in the construction sector. The mean thermal conductivity values of the particleboards (0.065–0.068 W/mK) were lower than those obtained in wood and similar to those in cork panels. The samples were tested with frequencies from 50 to 6300 Hz. In all cases, the results allowed us to conclude that they were better sound absorbers than commercial wood and plywood panels of the same average density for low frequencies, and with similar values for medium and high frequencies. The mechanical results reached the minimum requirement to be considered as boards for general use and, specifically with particles from 0.25 to 1.00 mm, for furniture according to European standards. The particle size of the particleboards was the variable that influenced all the acoustic properties, but did not affect the thermal conductivity. The experimental results indicated that the thermal and acoustic properties of these particleboards were promising for their application in commercial uses.

Interaction between particle size and mixing ratio on porosity and properties of tea oil camellia (Camellia oleifera Abel.) shells-based particleboard

This study investigated the interaction between particle size and mixing ratio on the porosity of particleboard and in consequence its effect on the physical and mechanical properties of panels. Tea Oil Camellia Shell (TOCS), which could provide 1.8 million tons of lignocellulose raw material annually, can be a useful resource for particleboard production. In that regard, particleboards with different particle sizes (coarse and fine) and mixing ratios (wood and TOCS) bonded with Polymethylene polyphenyl polyisocyanate (pMDI) were investigated. The results showed that particleboard made with TOCS particles had higher densities than those of commercial wood particles. Furthermore, particleboards made with fine particles had lower porosity. The average values for physical and mechanical properties have shown that except for thickness swelling (TS), most properties were better with coarse particles. In terms of all properties, results showed that adding 50% of commercial wood in conjunction with TOCS particles regardless of particle size can offer acceptable results, which qualified all requirements of EN 312:2010 standard for P2-type particleboard (boards for interior fitments (including furniture) for use in dry conditions). In addition, due to the porous structure of the shells, TOCS-based particleboards have better thermal conductivity compared to wood-based particleboards.

Genome-Wide Identification of Eucalyptus Heat Shock Transcription Factor Family and Their Transcriptional Analysis under Salt and Temperature Stresses.

Heat shock transcription factors (HSFs) activate heat shock protein gene expression by binding their promoters in response to heat stress and are considered to be pivotal transcription factors in plants. Eucalyptus is a superior source of fuel and commercial wood. During its growth, high temperature or other abiotic stresses could impact its defense capability and growth. Hsf genes have been cloned and sequenced in many plants, but rarely in Eucalyptus. In this study, we used bioinformatics methods to analyze and identify Eucalyptus Hsf genes, their chromosomal localization and structure. The phylogenetic relationship and conserved domains of their encoded proteins were further analyzed. A total of 36 Hsf genes were identified and authenticated from Eucalyptus, which were scattered across 11 chromosomes. They could be classified into three classes (A, B and C). Additionally, a large number of stress-related cis-regulatory elements were identified in the upstream promoter sequence of HSF, and cis-acting element analysis indicated that the expression of EgHsf may be regulated by plant growth and development, metabolism, hormones and stress responses. The expression profiles of five representative Hsf genes, EgHsf4, EgHsf9, EgHsf13, EgHsf24 and EgHsf32, under salt and temperature stresses were examined by qRT-PCR. The results show that the expression pattern of class B genes (EgHsf4, EgHsf24 and EgHsf32) was more tolerant to abiotic stresses than that of class A genes (EgHsf9 and EgHsf13). However, the expressions of all tested Hsf genes in six tissues were at different levels. Finally, we investigated the network of interplay between genes, and the results suggest that there may be synergistic effects between different Hsf genes in response to abiotic stresses. We conclude that the Hsf gene family played an important role in the growth and developmental processes of Eucalyptus and could be vital for maintaining cell homeostasis against external stresses. This study provides basic information on the members of the Hsf gene family in Eucalyptus and lays the foundation for the functional identification of related genes and the further investigation of their biological functions in plant stress regulation.