Search Results (30)

During the natural growth of trees, a large number of branches are formed, with a negative impact on timber quality. Therefore, pruning is an essential measure in forest cultivation. In this work, the effect of pruning on poplar timber quality was evaluated. This study used an artificial forest of Populus deltoides “Nanlin 3804”, established in 2014, as the research object. Pruning was carried out in March 2018 and March 2020 with a pruning intensity of one-third, and a control group was also set up. In December 2023, the growth of 11-year-old poplars under different treatments was investigated and analyzed, and sample trees were cut down for a wood property analysis. The results showed that pruning did not have a significant effect on the growth of the diameter at breast height, the tree height, or the volume. However, pruning could significantly facilitate the forming of higher-quality timber with smaller knots. Compared to unpruned wood, the ring width decreased 1–2 years after pruning, while it turned out to be greater than that of the control 3 years after pruning. Moreover, pruning can reduce the degree of trunk tapering. The fiber aspect ratio two years after pruning was greater than that of the control. The distribution frequency of fiber lengths of between 1500 μm and 1900 μm and that of fiber widths of between 32 μm and 38 μm were higher than that of the control. However, pruning had little effect on their density and oven-dried shrinkage. In addition, compared to the control, the bending strength and the modulus of elasticity increased by approximately 11%–14%, the impact toughness decreased by approximately 5%, and the compressive strength increased by approximately 6%. Pruning proved to be a successful method to improve the timber quality. Full article

With growing worldwide interest in constructing larger and taller wooden buildings, wood properties, such as the dynamic modulus of elasticity (${MOE}_{dyn}$), have become increasingly important. However, the ${MOE}_{dyn}$ of trees and logs has rarely been considered in forest management because a method for estimating the ${MOE}_{dyn}$ of logs based on standing tree characteristics has been lacking. Herein, we explored the multiple relationships between the ${MOE}_{dyn}$ of logs and standing tree characteristics of Japanese cedar (Cryptomeria japonica) such as tree height, diameter at breast height (DBH), and tree age, including the stress-wave velocity of the tree, which is known to be correlated with the ${MOE}_{dyn}$ of logs. The relationship between the ${MOE}_{dyn}$ of logs and standing tree characteristics was investigated by considering the bucking position. Different trends between the bottom logs and upper logs were found for all characteristics, showing a multiple trend of tree characteristics with the ${MOE}_{dyn}$ of logs based on the bucking position. The top three generalised linear mixed models for the prediction of the ${MOE}_{dyn}$ of logs showed relatively high accuracies when the bucking position was considered as a random effect. Although the contribution of the stress-wave velocity of the tree was relatively high, adding tree age improved the accuracy of the model, and this model was selected as the top model. The model for the bottom log, utilising the stress-wave velocity and age of the tree as explanatory variables, was highly explanatory (R² = 0.70); however, the best model for upper logs was only moderately explanatory (R² = 0.44). In addition, tree height and DBH were selected as explanatory variables along with tree age in the second and third models, which suggested the importance of growth rate rather than tree size. Therefore, adding correlates associated to characteristics related to height growth, such as site index, and DBH growth, such as stand density, is expected to improve model accuracy. Full article

Fraxinus griffithii C. B. Clarke is introduced from Taiwan to Thailand by the Royal Project Foundation beginning of the 1980s for highland rehabilitation. To improve the growth traits and tree form characteristics, a tree breeding program for this species has been initiated. In the present study, we evaluated the among seed sources variations in growth traits (diameter at 1.3 m above the ground [DBH] and tree height) and wood traits (basic density [BD], modulus of elasticity [MOE], modulus of rupture [MOR], and compressive strength parallel to the grain [CS]) of 10-year-old F. griffithii trees originated from 15 seed sources planted in highland areas of Thailand. The mean values of measured trees were 7.25 cm in DBH, 11.59 m in tree height, 0.76 g/cm³ in basic density, 9.74 GPa in MOE, 100.78 MPa in MOR, and 38.46 MPa in CS, respectively. Broad-sense heritability ranged from 0.13 to 0.16 in growth traits and 0.02 to 0.85 in wood traits. As a result of principle component analysis and cluster analysis, 15 seed sources were classified into three groups. Of the three groups, one showed good performance in both growth and wood traits. Significant phenotypic and genetic correlations were found between growth traits and between wood traits. However, no significant correlations were found between growth and wood traits. Based on the results, it is concluded that progeny with good performance of both growth and wood traits can be produced from the combinations of superior seed sources tested in the present study. Full article

In linear elastic fracture mechanics, the stress intensity factor describes the magnitude of the stress singularity near a crack tip caused by remote stress and is related to the rate of fatigue crack growth. The literature lacks SIF solutions for cracks emanating from a three-dimensional semi-ellipsoidal pit. This study undertakes a comprehensive parametric investigation of the Mode I stress intensity factor ${(K}_I)$ concerning cracks originating from a semi-ellipsoidal pit in a plate. This work utilizes finite element analysis, controlled by Python scripts, to conduct an extensive study on the effect of various pit dimensions and crack lengths on $K_I$. Two cracks in the shape of a circular arc are introduced at the pit mouth perpendicular to the loading direction. The $K_I$ values are calculated using the displacement extrapolation method. The effect of normalized geometric parameters pit-depth-to-pit-width $(a/2c$), pit-depth-to-plate-thickness $(a/t)$, and crack-radius-to-pit-depth $(R/a)$ are investigated. The crack-radius-to-pit-depth $(R/a)$ is found to be the dominating parameter based on correlation analysis. The data obtained from 216 FEA simulations are incorporated into a predictive model using a k-dimensional (k-d) tree and k-Nearest Neighbour (k-NN) algorithm. Full article

Mytilaria laosensis, a common fast-growing tree species in southern China, boasts excellent growth speed and attractive color and texture. However, due to its short growth cycle and high proportion of juvenile wood, it typically exhibits poor dimensional stability and low strength, which significantly limits its practical applications. This study uses vacuum impregnation to modify M. laosensis wood with polyethylene glycol (PEG), focusing on the effects and mechanisms of PEG with different molecular weights on wood properties. The results indicate that PEG enters the wood cell walls through capillary action and diffusion, forming hydrogen bonds with the free hydroxyl groups on cellulose and hemicellulose, which keeps the cell walls swollen and enhances dimensional stability. Post modification, the dimensional stability of M. laosensis wood improved, with an anti-swelling efficiency ranging from 61.43% to 71.22%, showing an initial increase followed by a decrease with increasing PEG molecular weight. The optimal PEG molecular weight for anti-swelling efficiency was 1500 Da, achieving 71.22%. The flexural modulus of elasticity and flexural strength of the treated wood also first decreased and then increased with increasing PEG molecular weight. Among them, the PEG1000-treated material showed the best performance, with the flexural modulus of elasticity increased by about 29% and the flexural strength increased by about 5% compared to untreated wood. Additionally, PEG, having a higher pyrolysis temperature than wood, raised the initial pyrolysis temperature and maximum pyrolysis rate temperature of M. laosensis wood, thus improving its thermal stability. These findings provide scientific evidence and technical support for the efficient utilization and industrialization of M. laosensis wood, promoting its widespread application and industrial development. Full article

To explore the radial variation in wood properties of slash pine (Pinus elliottii Engelm.) during its growth process and to achieve the early prediction of these properties, our study was carried out in three slash pine harvest-age plantations in Ganzhou, Jian, and Jingdezhen, Jiangxi province of South China. Wood core samples were collected from 360 sample trees from the three plantations. SilviScan technology was utilized to acquire wood property parameters, such as tangential fiber widths (TFWs), radial fiber widths (RFWs), fiber wall thickness (FWT), fiber coarseness (FC), microfibril angle (MFA), modulus of elasticity (MOE), wood density (WD) and ring width (RD). Subsequent systematic analysis focused on the phenotypic and radial variation patterns of wood properties, aiming to establish a clear boundary between juvenile and mature wood. Based on determining the boundary between juvenile and mature wood, a regression equation was used to establish the relationship between the properties of juvenile wood and the ring ages. This relationship was then extended to the mature wood section to predict the properties of mature wood. Our results indicated significant differences in wood properties across different locations. The coefficients of variation for RD and MOE were higher than other properties, suggesting a significant potential for selective breeding. Distinct radial variation patterns in wood properties from the pith to the bark were observed. The boundary between juvenile and mature wood was reached at the age of 22. The prediction models developed for each wood property showed high accuracy, with determination coefficients exceeding 0.87. Additionally, the relative and standard errors between the measured and predicted values were kept below 10.15%, indicating robust predictability. Mature wood exhibited greater strength compared to juvenile wood. The approach of using juvenile wood properties to predict those of mature wood is validated. This method provides a feasible avenue for the early prediction of wood properties in slash pine. Full article

The need, or even the obligation, to take care of the natural environment compels a search for new technological solutions, or for known solutions to be adapted to new applications. The maxim is ‘don’t harm, but improve the world for future generations’. In the wood industry in particular, given that it is based on a natural raw material, we must look for ecological solutions. Trees grow, but the demand for wood exceeds the volume of tree growth. In industrial manufacturing, one of the ways to make full use of wood is through chipless processing, which occurs during rotary cutting (peeling). In addition, wood is a natural material, each fragment of which has a range of properties. In addition, wood defects in quality manipulation generate a lot of waste. The aim of this study was to analyse the quality effect of the tested layered composites for flooring materials on production application. The practical purpose was to exchange actual sawing-based production for chipless production. The composite base layers were made of pine wood (Pinus L.) veneers with differing quality classes. The samples were subjected to three-point bending tests to calculate the moduli of elasticity and stiffness, which are the most important parameters. Because both analysed parameters describe product quality, the analyses were based on the creation of Shewhart control charts for each parameter. In theory, these control charts are tools for analysing whether the production process is stable and yields predictable results. To have full control over the process, five elements have to be applied: central line (target), two types of control lines (upper and lower) and two types of specification lines (upper and lower). New types of layered composites for flooring may be applied to production once verified using Shewhart control charts. It turns out that it is possible to produce the base layer of the flooring materials using the rotary cutting (peeling) method without having to analyse the quality of the raw material. This is a way to significantly increase the efficiency of production in every element of manufacturing. Full article

The South Korean residential real estate market is influenced by both the traditional dynamics of demand and supply and external factors such as housing policies and macroeconomic conditions. Considering the proportion of housing assets in individual wealth, market fluctuations can have significant implications. While previous studies have utilized variables such as GDP growth rate, patent issuance, and birth rate, and employed models such as LSTM and ARIMA for housing price predictions, many have overlooked the influence of local factors. In particular, there has been insufficient investigation into the impact of subway stations and living social overhead capital facilities on housing prices, especially in metropolitan areas. This study seeks to bridge this gap by analyzing the usage trends of subway stations, evaluating the impact of living social overhead capital facilities on housing values, and deriving the optimal machine learning model for price predictions near subway stations. We compared and analyzed a total of eight machine learning regression models, including Linear Regression, Decision Tree, Random Forest, LightGBM, Ridge, Lasso, Elastic Net, and XGBoost, all of which are popular regression models, especially in the context of machine learning and data science. Through comparative analysis of these machine learning techniques, we aim to provide insights for more rational housing price determinations, thereby promoting stability in the real estate market. Full article

Poplar plantations can acclimate to drought stress in semi-arid areas, where the variation of stand age may result in varied water adaptation strategies presented as hydrodynamic performance. In this study, nine mature Populus simonii Carr. individuals were targeted as sampling objects in plantations characterized to three stand ages: young (9 yr), middle-aged (17 yr), and near-mature (29 yr) stages in a semi-arid area of western Liaoning, Northeast China. Hydraulic traits were investigated as parameters of leaf pressure-volume curves, xylem embolism vulnerability curves, hydraulic structure, and wood density (WD). Results showed that osmotic potential (Ψ_tlp) and relative water content at the turgor loss point and cell-wall bulk elastic modulus were lowest in middle-aged stands (−2.19 MPa; 86.71%; 13.75 MPa). Stem and leaf-specific hydraulic conductivity (K_s and LSC) were all the highest in middle-aged stands. Xylem embolism vulnerability (P₅₀) and lethal water potential of trees (P₈₈) increased with the growth of stand age. Young stands faced minimal risk of hydraulic failure according to the stomatal safety margin (SSM_tlp, Ψ_tlp minus P₅₀), which was consistent with the comprehensive evaluation results of the principal component analysis. WD was related to P₈₈ (R²= 0.51; p < 0.05). P₅₀ was related to drought avoidance traits Ψ_tlp (r = 0.76; p < 0.05) but not to xylem efficiency (K_s). Overall, WD can be an excellent proxy for hydraulic safety monitoring. Young and middle-aged Populus simonii populations are more adaptable to drought conditions than near-mature populations, and near-mature stands should receive intermediate cuttings to avoid exposure to drought stress. Full article

Leaf chlorophyll content (LCC) is a crucial indicator of nutrition in apple trees and can be applied to assess their growth status. Hyperspectral data can provide an important means for detecting the LCC in apple trees. In this study, hyperspectral data and the measured LCC were obtained. The original spectrum (OR) was pretreated using some spectral transformations. Feature bands were selected based on the competitive adaptive reweighted sampling (CARS) algorithm, random frog (RF) algorithm, elastic net (EN) algorithm, and the EN-RF and EN-CARS algorithms. Partial least squares regression (PLSR), random forest regression (RFR), and the CatBoost algorithm were used before and after grid search parameter optimization to estimate the LCC. The results revealed the following: (1) The spectrum after second derivative (SD) transformation had the highest correlation with LCC (–0.929); moreover, the SD-based model produced the highest accuracy, making SD an effective spectrum pretreatment method for apple tree LCC estimation. (2) Compared with the single band selection algorithm, the EN-RF algorithm had a better dimension reduction effect, and the modeling accuracy was generally higher. (3) CatBoost after grid search optimization had the best estimation effect, and the validation set of the SD-EN-CARS-CatBoost model after parameter optimization had the highest estimation accuracy, with the determination coefficient (R²), root mean square error (RMSE), and relative prediction deviation (RPD) reaching 0.923, 2.472, and 3.64, respectively. As such, the optimized SD-EN-CARS-CatBoost model, with its high accuracy and reliability, can be used to monitor the growth of apple trees, support the intelligent management of apple orchards, and facilitate the economic development of the fruit industry. Full article

The aim of this study is to analyze the properties of Paulownia tomentosa x elongata plantation wood from Serbia, considering the influence of the stem height (0 to 1 m and 4.5 to 6 m above soil level—height spot) and radial position from the pith to bark (in the core, near the bark, and in between these zones—cross-section spot). The results show that most properties are improved when the samples were taken from upper parts of the tree (height spot) and from the near bark spot (cross-section spot). The mean density measured 275 kg/m³ at the stem height between 4.5–6 m and 245 kg/m³ for the samples collected from 0–1 m trunk height. The density had the highest value on the spot near bark (290 kg/m³), for the mature wood at a height of 4.5–6 m, and near pith had a mean density of 230 kg/m³. The Brinell hardness exhibited highest values in the axial direction (23 N/mm²) and near bark (28 N/mm²). The bending strength was 41 N/mm² for the trunk’s height range of 4.5–6 m and 45 N/mm² in the cross-section, close to cambium. The three-point modulus of elasticity (MOR) of the samples taken at a stem height of 4.5 to 6 m was up to 5000 N/mm², and on the spot near bark, the MOR measured 5250 N/mm². Regarding compressive strength, in the cross-section, near the pith, the mean value was the highest with 23 N/mm² (4.5–6 m), whilst it was 19 N/mm² near bark. The tensile strength was, on average, 40 N/mm² for both 0–1 m and 4.5–6 m trunk height levels and 49 N/mm² between bark and pith. The screw withdrawal resistance measured 58 N/mm for the samples extracted at a stem height of 4.5 to 6 m and 92 N/mm for the specimens collected near pith. This study stresses the influence, in short-rotation Paulownia timber, of indicators, such as juvenile and mature wood (difference emphasized after the fifth year of growth) and height variation, on the physical and mechanical properties of sawn wood. This study will help utilize more efficient sustainable resources, such as Paulownia plantation wood. This fast-growing hardwood species from Europe is adequate as a core material in sandwich applications for furniture, transport, sport articles, and lightweight composites, being considered the European Balsa. Full article

Paulownia wood has raised high attention due to its rapid growth and fire resistance. The number of plantations in Portugal has been growing, and new exploitation methods are needed. This study intends to determine the properties of particleboards made with very young Paulownia trees from Portuguese plantations. Single layer particleboards were produced with 3-year-old Paulownia trees using different processing parameters and different board composition in order to determine the best properties for use in dry environments. The standard particleboard was produced at 180 °C and a 36.3 kg/cm² pressure for 6 min using 40 g of raw material with 10% urea-formaldehyde resin. Higher particle size lead to lower-density particleboards, while higher resin contents lead to higher density of the boards. Density has a major effect on board properties with higher densities improving mechanical properties such as bending strength, modulus of elasticity (MOE) and internal bond, lower water absorption but higher thickness swelling and thermal conductivity. Particleboards meeting the requirements for dry environment according to NP EN 312 standard, could be produced with young Paulownia wood with acceptable mechanical and thermal conductivity properties with density around 0.65 g/cm³ and a thermal conductivity of 0.115 W/mK. Full article

The growth in the volume of modern construction and the manufacture of reinforced concrete structures (RCSs) presents the goal of reducing the cost of building materials without compromising structures and opens questions about the use of environmentally friendly natural raw materials as a local or full replacement of traditional mineral components. This can also solve the actual problem of disposal of unclaimed agricultural waste, the features of which may be of interest to the construction industry. This research aimed to analyze the influence of preparation factors on concrete features with partial substitution of coarse aggregate (CA) with rubber tree (RT) seed shells and to determine the optimal composition that can make it possible to attain concrete with improved strength features. CA was replaced by volume with RT seed shells in an amount from 2% to 16% in 2% increments. Scanning electronic microscopy was employed to investigate the structure of the obtained concrete examples. The maximum increase in strength features was observed when replacing coarse filler with 4% RT seed shell by volume and amounted to, for compressive and axial compressive strength (CS) and tensile and axial tensile strength (TS) in twisting, 6% and 8%, respectively. The decrease in strain features under axial compression and under axial tension was 6% and 5%, respectively. The modulus of elasticity increased to 7%. The microstructure of hardened concrete samples with partial replacement of CA with RT seed shells in the amount of 2%, 4% and 6% was the densest with the least amount of pores and microcracks in comparison with the structure of the sample of the control composition, as well as samples with the replacement of CA with RT seed shells in an amount of more than 6%. The expedient effective replacement of CA with RT shells led to a reduction in battered stone of up to 8%. Full article

To select excellent clones characterized by fast growth and high-quality wood of Catalpa fargesii Bur., growth traits, including height and diameter at breast height (DBH) at 1, 9, 11 and 13 years old, were collected and wood properties, including the Pilodyn value and elastic modulus at age 13 of 200 clones of C. fargesii from different ecological areas (four provinces), were measured. Genetic variation analysis and repeatability estimation were carried out. The correlation between the characteristics and the correlation between the characteristics and the geographical and climatic factors were analyzed. Excellent clones were selected by a comprehensive evaluation method combined with breeding values. The traits of C. fargesii were significantly different among the clones. The coefficient of variation (CV) ranged from 12.12% to 26.17%, and the repeatability (R) ranged from 0.79 to 0.97. The growth traits among ages of 9, 11 and 13 were significantly correlated, and the growth traits at ages of 9, 11 and 13 and Pilodyn values at the age of 13 were positively correlated with altitude and negatively correlated with longitude. Tree growth at ages of 11 and 13 showed a high negative correlation with wood properties. The suitable tree age for the early selection of clones with excellent growth and wood properties is 11 years old. Nine clones with excellent growth, six clones with high-quality wood and three clones with great growth and wood properties were selected, which laid a foundation for further optimization of C. fargesii clones. Additionally, C. fargesii clones in the western and high-altitude areas featured fast growth, while those in the eastern and low-altitude areas had better wood properties. This study serves as a reference for the selection of C. fargesii clones in different ecological areas. Full article

Liver Kinase B1 (LKB1) is a serine/threonine kinase that can regulate energy metabolism and skeletal muscle growth. In the present study, LKB1 cDNA of triploid crucian carp (Carassius auratus) was cloned. The cDNA contains a complete open reading frame (ORF), with a length of 1326 bp, encoding 442 amino acids. Phylogenetic tree analysis showed that the LKB1 amino acid sequence of the triploid crucian carp had a high sequence similarity and identity with carp (Cyprinus carpio). Tissue expression analysis revealed that LKB1 was widely expressed in various tissues. LKB1 expressions in the brain were highest, followed by kidney and muscle. In the short-term LKB1 activator and inhibitor injection experiment, when LKB1 was activated for 72 h, expressions of myogenic differentiation (MyoD), muscle regulatory factor (MRF4), myogenic factor (MyoG) and myostatin 1 (MSTN1) were markedly elevated and the content of inosine monophosphate (IMP) in muscle was significantly increased. When LKB1 was inhibited for 72 h, expressions of MyoD, MyoG, MRF4 and MSTN1 were markedly decreased. The long-term injection experiment of the LKB1 activator revealed that, when LKB1 was activated for 15 days, its muscle fibers were significantly larger and tighter than the control group. In texture profile analysis, it showed smaller hardness and adhesion, greater elasticity and chewiness. Contrastingly, when LKB1 was inhibited for 9 days, its muscle fibers were significantly smaller, while the gap between muscle fibers was significantly larger. Texture profile analysis showed that adhesion was significantly higher than the control group. A feeding trial on triploid crucian carp showed that with dietary lysine-glutamate dipeptide concentration increasing, the expression of the LKB1 gene gradually increased and was highest when dipeptide concentration was 1.6%. These findings may provide new insights into the effects of LKB1 on fish skeletal muscle growth and muscle quality, and will provide a potential application value in improvement of aquaculture feed formula. Full article