Research Articles

Dependence curves for the kappa number of digester pulp (KN_DP), total pulp yield (TY), screened pulp yield (SY), and reject content in digester pulp (R_DP) as a function of the kappa number of screened pulp (KN_SP) were determined based on the results of several dozen kraft pulping tests of pine wood chips (Pinus sylvestris). These curves were then analyzed to assess whether their course could be used to distinguish qualitative types of pine kraft pulps and to determine the boundary values of the KN_DP, TY, SY, and R_DP indices for these types. Relationships of the form R_DP = f(KN_SP) were found to be particularly useful for this purpose. The identified types of pine kraft pulps and the limiting values of the parameters used to assess pulping process efficiency are presented in a table at the end of the paper.

Physical, mechanical, and quality characteristics of Uludağ fir (Abies nordmanniana subsp. bornmuelleriana) wood, which occurs naturally in Turkey, were determined. The effect of site classes (SCs) on these characteristics was investigated. Uludağ fir trees growing naturally in the Şerif Yüksel Forest Management District and belonging to different site classes (I, II, and III) were considered. The physical and mechanical properties of the test samples were determined in accordance with relevant standards, and differences between SCs were evaluated using statistical methods. SCs were found to have a statistically significant effect on the physical and mechanical properties of Uludağ fir wood (p<0.05). The highest performance in terms of physical and mechanical properties was generally observed in samples from Class II. Static quality (SQ) values ranged from 9.52 to 10.9, while dynamic quality (DQ) values ranged from 1.77 to 1.98. Based on DQ values, samples from all quality classes fell into the group of wood exhibiting high elastic properties; based on SQ values, they were classified as high-quality wood. The findings highlight the impact of SCs on the quality characteristics of Uludağ fir wood, providing important scientific data for quality-focused raw material selection, sustainable forest management, and the planning of wood usage areas.

The impact of internal uniformity was studied relative to the insulation performance and properties of mycelium-based insulation boards (MBI) made from Lentinus sajor-caju and corn husk. The study examined how variations of mass per unit area and board thickness affected density, thermal conductivity, thermal resistance, and heat capacity. Density gradients were observed in the boards, ranging from 157 to 181 kg/m³, highest at the centerline and lowest at the edges. Thermal conductivity increased with density (0.049 to 0.063 W·m⁻¹·K⁻¹), while thermal resistance increased from center to edge, peaking at 0.471 m²·K·W⁻¹ at the 24 mm edge. Heat capacity was stable across samples (0.132 to 0.143 kJ/kg·K), indicating consistent thermal energy retention. Microscopic analysis confirmed these trends, showing structural compaction at the center and greater porosity at the edges, correlating with insulation performance. Pearson correlation analysis confirmed strong relationships between density, position, and thermal properties, notably a significant negative correlation between density and distance from the edge (r = -0.858, p = 0.003 at 16 mm thickness) and a strong positive correlation between thickness and thermal resistance (r = 0.999, p < 0.001). These findings support MBI boards as eco-friendly, high-potential alternatives to traditional insulation materials, allowing for further performance enhancement through optimized growth and mold design.

To achieve high-value utilization of lignin and develop high bio-based content materials, flexible films were prepared via Schiff base reaction of levulinic acid-esterified lignin with castor oil amine and varying amounts of polyether amine (0 to 50 wt.%). The incorporation of polyether amine as a flexible plasticizing component effectively addressed the inherent brittleness of high-lignin-content films, resulting in tunable mechanical properties. Tensile testing showed that V-3 (15% polyether amine) exhibited the highest tensile strength (12.0 MPa) and Young’s modulus (7.19 GPa), representing increases of 51% and 318% compared to V-1 (the 0% polyether amine), while maintaining an elongation at break of 75.9%. All films exhibited good thermal stability with T_d 5% above 272 °C. Swelling ratio measurements increased from 109% (V-1) to 209% (V-5), indicating decreasing crosslinking density with higher polyether amine content. Notably, V-3 exhibited a T_g of 35.8 °C. This study demonstrates a simple strategy for tuning the mechanical properties of lignin-based films for potential biomedical and soft robotics applications.

Hepatocellular carcinoma (HCC) is a major global health burden, and there is an urgent need to develop novel therapeutic agents with more efficacious safety profiles. In the current studies, methanolic leaf extract of Passiflora edulis was characterized for its phytochemical composition and biological activities in an integrated in vitro and in silico approach. Qualitative phytochemical screening indicated that bioactive secondary metabolites such as flavonoids, saponins and steroids were present. The extract showed concentration-dependent antioxidant activity, with 81% DPPH radical scavenging at a maximum, suggesting potent free radical neutralization capability. The MTT assay was used to assess cytotoxicity in HepG2 human liver cancer cells, finding a moderate antiproliferative effect with an IC₅₀ value of 251 µg/mL. GC–MS analysis revealed different phytoconstituents and 13-docosenamide (Z) was predominant, however included some compounds as hexadecane and N-isopropyl-3-phenylpropanamide. The molecular docking studies showed moderate binding affinities (−6.5 to −7.8 kcal/mol) of selected compounds against the target protein (PDB ID: 3GCW), which represented PCSK9–LDLR complex. Significantly, N-isopropyl-3-phenylpropanamide demonstrated the most favourable binding interactions by engaging in both hydrogen bonding and hydrophobic interactions with key amino acid residues, indicating potential modulation of protein function. Since the PCSK9–LDLR axis plays a crucial role in lipid metabolism and has also become increasingly implicated in HCC progression, these results suggest that the biological activity of P. edulis extract may be mediated through multi-target interactions with cancer-associated metabolic pathways. Nonetheless, moderate cytotoxic potency and basic extract evaluation justify further studies. Bioactivity-guided fractionation will be necessary to identify active P. edulis–derived compounds, the mechanism of action needs further validation, and in vivo evaluation should be performed toward demonstrating their therapeutic potential.

In order to solve the problem of spoilage of mulberry after harvest, this study discusses the effect of various concentrations of composite preservatives on the preservation effect of mulberry, so as to achieve the purpose of prolonging its shelf life. Taking mulberry as raw material, three preservatives of bamboo vinegar, polyvinyl alcohol, and citric acid were selected, and the physical and chemical indexes used were sensory evaluation, firmness, weight loss rate, decay percentage, soluble solid content, vitamin C content, and POD activity, and the optimal concentration of each preservative was determined to be 1.0% bamboo vinegar, 3.0% polyvinyl alcohol (PVOH), and 1.0 % citric acid by single factor test at room temperature. The orthogonal test screened 1.0% bamboo vinegar, 3.5% PVOH, and 0.8% citric acid as the optimal compound combination, which could effectively extend the shelf life of mulberry for at least 48 h compared to the blank control and commercial groups. This study provided a safe and efficient compound preservative solution for mulberry preservation.

The nutrient profile and pharmaceutical activities were analyzed for seaweeds (Ascophyllum nodosum, Sargassum polycystum, Sargassum cristaefolium, Hormophysa cuneiformis, and Hormophysa triquetra) in the fish diet. The total protein content was greatest (8.4±0.2%) in S. polycystum, and the highest lipid content was detected in S. cristaefolium (3.7±0.1%). The crude fiber content was greatest (13.8±0.7%) in S. polycystum, and the carbohydrate content was high (35.2±0.5%) in S. polycystum. The phenol (73.1±1.1 mg GAE/g DW) and flavonoid (85.2±1.1 mg CE/g DW) contents were high in S. polycystum, whereas the tannin content was high in S. cristaefolium (15.5±0.8 mg GAE/g DW). Sargassum polycystum presented the maximum DPPH activity (64.4±2.2%) and H₂O₂ activity (45.8±1.3%). Equal amounts of seaweed (A. nodosum, S. polycystum, S. cristaefolium, H. cuneiformis, and H. triquetra) were mixed and used for feed formulation. The experimental diet was prepared by mixing 5% to 10% seaweed with other feed ingredients. The experimental diet was prepared with soybean oil, fish oil, and water. Compared with the control diet, the seaweed-supplemented diet improved fish growth (p<0.05). Overall, the results revealed the beneficial effects of seaweed on the feed of goldfish.

Individual and combined effects of thermal treatment and zinc borate (ZB) addition were studied relative to the mechanical properties and water resistance of oriental beech (Fagus orientalis Lipsky) wood-plastic composites (WPCs). Wood flour was thermally treated at 150 °C for 120 min under saturated steam before composite manufacturing. Flexural, tensile, impact, and water resistance properties were evaluated, and the data were analyzed using two-way ANOVA (p < 0.05). Thermal treatment increased the flexural strength from 57.2 MPa to 75.0 MPa, while the combined treatment produced the highest impact strength (7.56 J/m). Zinc borate-containing composites exhibited lower maximum water absorption (2.8 to 3.0%) than the control (8.6%), despite showing higher moisture diffusion coefficients. This indicated that the diffusion rate and equilibrium moisture uptake were driven by different mechanisms. SEM observations revealed that the combined treatment produced a more cohesive fracture morphology, although these changes were not accompanied by improved flexural or tensile strength. Overall, thermal treatment and zinc borate affected the performance characteristics through distinct mechanisms, providing an effective approach for improving the moisture resistance and durability of wood-plastic composites.

The modification of melamine-urea-formaldehyde (MUF) resin was studied using plant tannins, focusing on the effects of tannin addition stage and dosage on resin properties. Second-stage addition failed due to system gelation caused by the acidic polycondensation environment. Although third-stage addition further reduced free formaldehyde content, the resulting viscosity surge led to difficulties in glue spreading, accompanied by significant deterioration in bond strength and water resistance. First-stage addition of bayberry tannin yielded optimal results, with 6% identified as the critical optimal dosage. At this level, the resin exhibited a viscosity of 206 mPa·s, free formaldehyde content of 0.09%, dry and wet shear strengths of 7.2 and 5.8 MPa, and impact toughness of 6.8 kJ/m². Beyond 6% addition, viscosity increased exponentially, free formaldehyde rebounded, and water resistance deteriorated sharply. Differential scanning calorimetry (DSC) analysis revealed that tannin modification reduced the curing peak temperature (by 2.7°C for bayberry tannin) and accelerated crosslinking reactions. The first-stage addition of 6% bayberry tannin was determined as the optimal technical solution, achieving a balanced compromise among impact toughness, shear strength, formaldehyde reduction efficacy, and process feasibility.

This study investigated the optimization of phenolic compound recovery from Fraxinus mandshurica leaves residues generated by supercritical fluid extraction (SFE) to promote the sustainable use of resources. Using Box–Behnken design under response surface methodology, the optimal extraction conditions were determined to be an extraction temperature of 64.3 °C, an extraction time of 12.6 h, and an ethanol concentration of 76.3%. Under these conditions, the experimental yields of total polyphenol content and total flavonoid content were 63.41 ± 3.05 mg GAE/g and 5.12 ± 0.12 mg QE/g, respectively. These results showed high reliability, with relative errors below 10%. Biological analysis using RAW 264.7 cells revealed that the optimized extract exhibited non-toxicity up to a concentration of 125 µg/mL. At a treatment concentration of 62.5 µg/mL, it inhibited the production of nitric oxide and tumor necrosis factor-alpha (TNF-α) 38.0% and 15.8%, respectively, under inflammatory conditions induced by lipopolysaccharide (LPS). These results demonstrate that SFE residues from F. mandshurica leaves, which were previously considered waste, can be effectively upcycled into high-value functional materials for use in the pharmaceutical and food industries.