Research Articles

This study aimed to enhance the structural performance of a drift joint with a slotted-in steel plate using laminated timber made from small- to medium-diameter timbers. An analysis was conducted to compare and evaluate the structural performance and seismic behavior of laminated timber portal frames reinforced with fiber-reinforced plastic (FRP) laminates, such as glass fiber cloth (GFC), glass fiber reinforced plastic sheet (GS), and carbon-reinforced plastic sheet (CS), under low amplitude cyclic lateral loads, in comparison to unreinforced portal frames (UR). The reinforced portal frame, strengthened by FRP laminates, exhibited higher resistance to strength and stiffness strength degradation due to cyclic loading-induced degradation at low drift angles compared to the unreinforced frame affected by heterogeneous timber. The reinforced portal frame, particularly the GFC and GS, exhibited energy dissipation rates 32% and 17% higher than UR, respectively, making them the most effective in vibration damping. FRP laminates mitigated fiber direction cleavage from drift pin holes. The average maximum moment and average yield moment of the reinforced portal frame increased by 18% and 21%, respectively, due to the alleviation of joint failure. Finally, CS significantly affected the maximum moment, while GFC significantly influenced the yield moment.

Scots pine and spruce wood samples were vacuum impregnated with 3, 5, and 9% sodium bicarbonate solution. Contact angle measurements were made by dropping 0.05 mL of pure water and 3% saltwater solution onto the material’s surface. The surface roughness of each sample was measured, and that of Scots pine control samples was higher than that of spruce samples, but the surface roughness values of spruce wood were higher in the samples impregnated with sodium bicarbonate. When pure water or saltwater solution was dropped onto the samples, it was observed that as the waiting times increased, the contact angle value decreased, the droplet height decreased, and the droplet width increased. It was found that the contact angles were higher in the control samples of both tree species than in the samples of 5% and 7%. The contact angles of 9% impregnation solution, pure water, and salt water were higher than the control samples. As the solution ratio increased on the surfaces impregnated with sodium bicarbonate, the contact angle also increased, and the wettability behavior decreased accordingly. Sodium bicarbonate solution is effectively used in the impregnation process for pine and fir woods, making the materials more resistant to water under outdoor conditions. This solution significantly reduces the risk of deformation of wood by increasing the contact angle and reducing its water absorption properties.

Mechanical characteristics were studied for biodegradable plastics derived from avocado seed starch, emphasizing the influence of chitosan and glycerol. The extraction of starch from avocado seeds began with filtration. Different amounts of glycerol and chitosan were added to the extracted starch of up to 3% by weight. Because this method just uses distilled water instead of chemical chemicals, it was highly environmentally friendly. Tensile testing was done on the generated samples to assess the mechanical properties of this bioplastic; the results indicated that the samples’ elongation rates ranged from 21.9% to 134.7%. In spite of this, the bioplastic showed a comparatively low tensile strength, peaking at 3,381 MPa when chitosan-starch ratio was 2:1 and 1.5% glycerol was added.

The residue from pruning Cudrania tricuspidata trees is considered a rich source of energy and bioactive compounds. Recovering these compounds from C. tricuspidata tree pruning could help mitigate potential economic and environmental concerns. The primary aim of this study was to investigate the impact of extraction temperature, duration, and liquid-to-residue ratio on the antioxidant activity, total phenolic content, and total flavonoid content of C. tricuspidata tree pruning, using the response surface methodology. The results indicated that the microwave-assisted extraction temperature or microwave-assisted extraction time was the most crucial variable in the extraction process (Significance at p-value < 0.001 – 0.05 for antioxidant activity and chemical profile). It is worth mentioning that the optimal extraction conditions for achieving maximum 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation induction activity, total polyphenol content, and total flavonoid content were distinct from one another, necessitating specific optimization for each targeted characteristic. The optimized extraction conditions yielded 85.8% DPPH radical scavenging activity, 95.4% ABTS radical cation induction activity, 2.72 mg/g total polyphenol content, and 2.53 mg/g total flavonoid content. These results highlight the potential of C. tricuspidata as a valuable dietary source of phenolic antioxidants for human health.

The chemical compositions, antioxidant activities, and antimicrobial activities of the essential oils acquired from the separated parts of air-dried flowers, leaves, and stems of Alyssoides utriculata L. plant growing in Turkiye were determined. Three volatile oil components were acquired via hydrodistillation using a Clevenger apparatus and analyzed by the Gas Chromatography-Mass spectrometry/Flame Ionization Detection (GC-MS/FID) analysis. A total of 75, 67, and 76 compounds in the volatile oils of flower, leaves, and stem of A. utriculata were identified, respectively. The highest percentage of chemical compounds in the essential oils of A. utriculata were determined to be monoterpenes in flowers and leaves, (72.4% and 66.5%) and hydrocarbons (29.2%) in stems. While α-pinene (62.5% and 46.7%) was defined as the major compound in the flowers and leaves, nonane (21.2%) was determined to be so in the stem essential oil. The antioxidant activity of the obtained essential oils was determined according to free radical scavenging and total phenolic content (TPC), and antimicrobial activity against 12 bacteria and 5 fungi, using the agar dilution method. The amount of TPC and scavenging activity of the flower oil were found to be 440.61 ± 6.26 mg GAE/L and 46.00 ± 1.28%, respectively. Based on the antimicrobial activity results, all the essential oils of A. utriculata were determined to have antimicrobial activity against Escherichia coli and Bacillus subtilis.

The antibacterial performance of biocomposite films prepared from lignocellulosic waste (hazelnut husk or hazelnut leafy green cover) modified with silver nanoparticles and polylactic acid (PLA) was determined. The amount of hazelnut husk in the PLA matrix ranged from 10 to 40% by weight in 10% increments. The composite pellets were produced using a twin-screw extruder. Biocomposite films of 0.6 mm x 40 mm x 200 mm were produced from the pellets in a laboratory hydraulic hot press. The surfaces of the modified hazelnut husk and biocomposite specimens were analyzed by scanning electron microscopy (SEM) and inductively coupled plasma optical emission spectrometry (ICP-OES). The antibacterial activity of the biocomposite films against Staphylococcus aureus bacteria was determined using the ASTM E 2149 (2020) method. The antibacterial activity of the biocomposite films increased noticeably with the addition of hazelnut husk modified with the silver nanoparticles. Compared to the pure PLA film, the biocomposite films with 10 wt% modified husk flour showed the lowest antibacterial activity (31.3%) against S. aureus over 24-h while the films with 40 wt% showed the highest antibacterial activity (99.9%). The biocomposite films made of hazelnut husk flour with silver nanoparticles and PLA matrix could be considered for food packaging applications.

Mixtures of vegetable waste and leaves were used to prepare compost in piles. The carbon/nitrogen ratios of the biomass varied among the selected agricultural waste. Co-composting was carried out for six weeks with a starter culture. The organic matter of the leaves declined after four weeks of composting, and a stable compost was obtained after 42 days of composting. The compost temperature reached its maximum after 12 days and moisture content declined continuously up to 42 days. The pH value of the compost increased slowly during composting and reached a maximum after six weeks. The electrical conductivity of the compost was suitable for plant nutrition. The organic matter, as organic carbon, declined, and organic nitrogen was increased. The carbon/nitrogen ratio of the mature compost was decreased. The decreased levels of carbon/nitrogen ratio reflected the maturity of the compost. The organic matter (%) was maximum (>50%) before composting process and it decreased gradually. The seed germination index was higher after 42 days of composting. The compost-treated plant improved yield and green gram seeds showed the presence of antioxidant enzymes.

Oranges and eucalyptus trees are abundant sources of waste and pruning, generating secondary streams that can be converted into valuable products. Both species are broadly cultivated in Mexico. Essential oils from orange peels and eucalyptus leaves possess antimicrobial and antioxidant properties, making them useful in various applications. In this study, the essential oils antioxidant potential was determined through radical scavenging activity and ferric reducing capacity, and the total phenolic content was measured. These essential oils also demonstrated inhibition capacity against Escherichia coli and Staphylococcus aureus. GC-MS analysis of the oils revealed the composition of representative compounds, with D-limonene constituting almost 75% of the orange essential oil and 1,8-cineol comprising 15.2% of the eucalyptus oil. The antioxidant test results between essential oils showed that they are similar, except for the FRAP test, where eucalyptus essential oil obtained a value three times higher than orange essential oil. The findings suggest that these essential oils can serve as natural and sustainable alternatives to synthetic antimicrobial and antioxidant agents.

Rubber seed shell (Hevea brasiliensis) was used as a low-cost substrate to produce lactic acid via Lactobacillus plantarum LB2. The medium components were initially screened by two-level full factorial design. Three variables (pH, moisture, and polyoxyethylene sorbitan monooleate (PSM)) were used in the central composite design and response surface methodology. The amount of PSM was found to be a significant variable in lactic acid production. Lactic acid was purified and used for the chemical fabrication of a polylactic acid-chitosan composite film. Compared with the polylactic acid, the composite film improved the tensile strength, elongation strength, and tearing strength. The film prepared with 1% chitosan-polylactic acid exhibited the maximum antibacterial activity against Bacillus cereus (21 ± 1 mm) and the lowest activity against Escherichia coli (10 ± 1 mm). The polylactic acid-chitosan film prepared with 1% chitosan was used as a packing material to store the fish fillets and presented reduced mesophilic (4.3 ± 0.1 Log CFU/g) and psychrotropic (3.2 ± 0.2 Log CFU/g) bacterial populations compared with those of the control (4.9 ± 0.2 Log CFU/g and 3.7 Log CFU/g). Rubber seed shells can be used as an alternative culture medium for lactic acid production, to reduce the production cost of polylactic acid.

The production of lignocellulytic enzymes by microwave-radiated Pleurotus sajor-caju was assayed. Wheat straw was employed as substrate to P. sajor-caju for production of laccase, manganese peroxidase (MnPase), filter-paperase (FPase), carboxmethyl cellulase (CMCase), and cellulase (as evaluated using microcrystalline cellulose). P. sajor-caju exposed to 10 s of microwave radiation (MR) showed maximum growth with colony radius of 7.17 ± 0.45 cm, while with increasing the exposure time up to 50 s the growth decreased up to 2.67 ± 0.22 cm. Moreover, it failed to grow at 80 s of exposure time. Cellulase, MnPase, FPase, CMCase, and laccase activities were induced to 37 ± .0.54, 49 ± 2.36, 189 ± 2.12, 0.37 ± 0.06, and 1.58 ± 0.03 U/mL compared to that at control 31 ± 0.25, 46 ± 1.25, 177 ± 1.65, 0.28 ± 0.03, and 1.37 ± 0.12 U/mL, respectively as a result of P. sajor-caju exposure to 10 s of MR. As the exposure time increased, these enzymes activity decreased. Different levels of moisture with surfactant (polysorbate 80) were applied to optimize the enzymes activities at 10 s of exposure time. The optimum activities 3.15 ± 0.23, 0.62 ± 0.06, 269 ± 5.36, 65 ± 1.63, and 48 ± 0.98 U/mL were recorded for cellulase, MnPase, FPase, CMCase, and laccase, respectively at 70% of moisture and 0.15 mL/L of polysorbate 80.