Research Articles

This research investigated the influence of the layered structure of paper on its selected strength properties. Two types of cellulose pulp were used: unbleached kraft pine pulp (UBSK) and unrefined bleached birch kraft pulp (BHK). Multi-ply papers were obtained from layers of appropriate grammage formed separately and bonded in a wet state. Paper layers were formed from primary pulps (UBSK and BHK) or their mixtures (three-ply UBSK-BHK paper and three-ply UBSK-BHK-UBSK paper), from which various variants of laboratory paper samples were made. This work focused on three-layer papers. The obtained laboratory sheets were analysed for changes in tear resistance, tensile strength, bursting strength, short span compression strength (SCT), and corrugating medium test (CMT). In most cases, three-layer structures were characterised by higher strength parameters than single-layer papers. The tear strength and SCT of papers consisting of three layers formed from both mixed pulps were slightly lower than those of solid papers. The results demonstrate the feasibility of producing three-ply paper with significantly reduced variability in parameters such as elongation and bursting strength, which are inherently subject to high variability.

Some physical and mechanical properties of laminated timbers used in wooden construction and furniture industry were examined. Polyurethane (PU) glue was used in the production of laminates with 5 layers. The surface layers in each laminated timber (Glulam) were from the same wood type, and the core layers were from willow wood. The laminated timbers whose outer layers were made of willow (Salix alba L.), yellow pine (Pinus sylvestris L.), and ash (Fraxinus L.) wood had an air-dry density value of 0.60 g/cm³ in laminated timber with the highest ash wood surface. The pressure resistance parallel to the fibers was determined in the surface layer ash wood with 48.6 N/mm². It was found that the static bending resistance was 91.1 N/mm² in laminated timber with a surface layer of ash wood, and the modulus of elasticity value in bending was 10040 N/mm² in laminated timber with the highest ash wood surface. Thus, it has been seen in the study that improvements in physical and mechanical properties were achieved, especially as a result of combining willow wood (having fast growth potential and low density) with high-density wood types. According to the results of the study, it is recommended to carry out the necessary studies to increase the physical and mechanical properties of low-density wood types by laminating them with high-density wood types.

One of the biggest problems that threaten the production of strawberry in the world is the rapid damage and high rate of deterioration after harvest or during cold storage. Therefore, the current study was conducted to investigate the possibility of decreasing the post-harvest damage percentages and increasing the fruit quality of Fragaria x ananassa cv. ‘Estavana’ after harvest immediately or during the cold storage period. The strawberry plants were dipped for 3 to 5 minutes at 25 °C in a solution of 10 L made from distilled water and containing salicylic acid (SA) at 0, 250, 500, and 1000 mg/L or chitosan (CHIT) at 0, 2.5, 5, and 10 mg/L during the period of 0, 3, 6, 9, 12, and 16 days after harvesting. The results showed that the fruit firmness was notably decreased, and the loss and decay percentages were increased by increasing the period of storage, but it could be decreased by using SA or CHIT. Fruit content from soluble solids, total sugars and anthocyanin was significantly increased in the 16 days stored fruits treated with 500 mg/L SA or 50mg/L CHIT. Treating the fresh harvested without or with SA or CHIT increased the fruit content from vitamin C. The highest fruit content from titratable acidity was in the fresh harvested fruits compared with treated fruits with SA or CHIT.

To cope with low fertility rate and an aging population, China introduced and implemented a two-child policy to make an overall population adjustment. Because of this, there are now problems, such as the uncoordinated sleep space for the two children, competition between older children, insufficient care for older children, and additional family affairs. In view of this, this study focused on the two-child family and parents as the main users of wooden infant beds. The method of constructing I-Kano model was used to determine the needs of users and their importance. Based on the QFD theory, the user needs and engineering measures were analyzed and explored. Based on the TRIZ theory, the analysis of engineering conflict resolution was performed. Based on the results, the wooden infant bed design strategy was developed for the background of two-child policy. The purpose of this work is to meet the parenting needs of two-child families in various periods with the developed design strategy, avoid the parenting problems of two-child families, improve the parenting quality of two-child families, adjust the sleeping space of two-child families, and fill the vacancy in the design theory of wooden baby beds for two-child families.

Understanding the trajectory of changes in soil respiration (R_s) and soil organic carbon (SOC) with stand ages of the black pine (Pinus nigra Arnold) forest is essential for forest management and carbon budget estimates. In this research, changes of R_s and SOC were studied with respect to stand age in a chronosequence of three age classes of P. nigra plantations consisting of young (0 to 10-year-olds), middle-aged (11- to 20-year-olds), and pre-mature (35- to 45-year-olds) forest stands. R_s rates, soil temperature, and soil moisture were measured using an automated dynamic survey chamber (Li-8100A) for a year, encompassing summer, fall, winter, and spring seasons. Mean R_s significantly increased from young- to middle-aged and then stabilized, with effluxes ranging from 2.46 to 2.94 µmol CO₂ m^-2 s^-1. Forest litter significantly increased with stand age, but not the SOC in the mineral soil layers. The R_s showed a positive correlation with soil temperature (0.77) and air temperature (0.75) but not with soil moisture (-0.43). The present results highlight the importance of stand age in assessing carbon budget and provide essential information for forest managers and stakeholders in evaluating the potential of P. nigra forests as tools for carbon sequestration and mitigating global warming impacts.

The reliability was evaluated for frame construction with mortise and tenon (MT), dowel, and non-glued and glued staple joints made of beech wood. The moment capacities of the T-shaped joints were determined under static vertical loads. The MT joint had an average moment capacity of 204 Nm, followed by dowel joints (154 Nm). In staple joints, joint strength increased after gluing. A three-seat sofa frame was defined and theoretically subjected to loads on arm rails, side rails, and back posts. Moment levels on the joint of the frame were obtained by using the stiffness method. To measure the reliability, these moment levels were assumed to be normally distributed with a coefficient of variation of 10%; accordingly, the normal distribution of the data sets was transformed into a normal standard distribution, and then, the reliability of each joint on the frame was obtained by using probabilistic approaches. MT joints were found to have the highest moment capacity and, correspondingly, the highest reliability (99.99%). Gluing the staple joints increased the strength, so their reliabilities were increased. In designing frame construction, the critical joints should be determined, and then, the joinery system with the higher reliability should be used.

Wood fiber insulation (WFI) was studied as an eco-friendly alternative for fossil-based building insulation, focusing on its use in new wood fiber-insulated panels (WIPs). Rigid WFI boards with densities of 110, 140, and 180 kg/m³, including a 140 kg/m³ variant without paraffin wax, were evaluated. Key properties investigated included porosity, water vapor transmission, liquid water adsorption, and thermal conductivity. The porosity ranged between 85 and 92%, primarily influenced by density. Water vapor permeability ranged from 65 to 90 ng·s^-1m^-1Pa^-1, while liquid water absorption was between 2.5 and 20% by volume, influenced by both wax and density. The thermal conductivity coefficient ranged from 0.038 to 0.055 W/(m·K). Bond strength tests with WFI (140 kg/m³ with wax) laminated to various materials using structural adhesives showed tensile perpendicular-to-grain strengths of 10 to 16 kPa and shear strengths of 60 to 90 kPa, with failure only occurring within the WFI. It was concluded that WFI is a promising material for novel WIPs, offering competitive hygrothermal properties and compatibility with structural adhesives. However, its bio-based nature suggests variability and complexity, necessitating further rigorous testing in various climates and in more complex assemblies.

To reduce energy consumption, a new pulping process called A-D-E-RC (acidification/desalination/electrolysis/recycle-cooking) was developed by a research group in Guangxi University of China. The present work focuses on the step of recycle cooking (RC) to further investigate the technical feasibility of A-D-E-RC methods. Golden bamboo grass was considered as fiber source material for pulp, and it was cooked with the acidic treating of wastewater from black liquor. Then, the pulp obtained from each cooking was made into paper to test the changes in its physical properties.  As a result, the pulp yield increased from 43.9% to 50.2%, after re-using acidified black liquor, and the paper’s tear index and tensile index were improved. Therefore, this study demonstrated the feasibility of recycle cooking (RC) fiber materials for pulp applied the acidic treating wastewater from black liquor, and thereby, it further identifies the technical feasibility of A-D-E-RC pulping methods.

Free formaldehyde is released due to the addition of aldehyde-based adhesives during the production of fiberboard. This is harmful to human health and pollutes the environment, and for that reason binderless fiberboard has become a research hotspot. There have been reports about pretreatments with white-rot fungi or lignocellulase to produce binderless fiberboard, but there have been no such reports about optimizing the bio-pretreatment conditions. In this study, poplar wood shavings were used for fiberboard production, and the bio-pretreatment conditions with Coriolus versicolor were studied using response surface methodology. After single-factor optimization, the central levels of bran, molasses, and magnesium sulfate were obtained. Further optimization was carried out using Box-Behnken design to study the influence of the factors. A second-order polynomial equation was obtained, and the low p-value (0.001) implied that the model was highly significant. The optimized bio-pretreatment conditions for modulus of rupture (MOR) of the fiberboard were obtained by ridge analysis as 3.021 g of bran, 8.907 g of molasses, and 0.27 g of magnesium sulfate. Under the optimized conditions, MOR of fiberboard reached 27.21±0.64 MPa, which was 2.2 times that of the control fiberboard. Bio-pretreatment with C. versicolor should be a good choice to produce a high-strength binderless fiberboard.

Global climate change poses significant threats to ecosystems worldwide, particularly impacting long-lived forest tree species such as Pinus nigra. This study assessed the potential shifts in distribution areas for Pinus nigra, an important tree species, one highly vulnerable to global climate change, given its prevalence in continental climates, in Türkiye under different climate scenarios (SSPs 585 and 245). In this study, suitable distribution regions of Pinus nigra were evaluated based on SSPs 585 and SSPs 245 using nine different models. Results indicated potential losses in Pinus nigra distribution areas ranging from 15.0% to 43.5% (SSPs 245) and 19.7% to 48.9% (SSPs 585) by 2100. However, in 2100, new suitable distribution areas are expected to be formed at rates ranging from 13.8% to 32.1% and 15.1% to 34.4% according to the above scenarios. Because most of the newly formed suitable distribution regions are quite far from the areas where the species currently spreads, it seems necessary to provide the migration mechanism needed by the species by humans to prevent population losses in this process.