Research Articles

Pre-extraction of hemicellulose from eucalyptus heartwood and sapwood was conducted using the method of KOH extraction. Activated carbons (ACs) with high toluene adsorption capacity were prepared by using KOH as activator and hemicellulose-pre-extracted residue (HPR) as AC precursor. The findings indicated that the pore structure of the ACs could be regulated by adjusting the carbonization temperature. Using the HPR of eucalyptus heartwood as raw material, the activated carbon carbonized at 400 °C exhibited the highest BET surface area (3699 m²·g^-1) and pore volume (1.90 cm³·g^-1). The adsorption capacity of AC for toluene reached 816 mg·g^-1. The results showed that the adsorption capacity of toluene was associated with the micropores (< 2 nm) in the AC. Optimizing the carbonization temperature could enhance the proportion of micropores, thereby significantly enhancing the activated carbon’s adsorption capacity for toluene.

This study focuses on the wooden columns of a historic residential structure to assess their integrity. Employing non-invasive computed tomography (CT) scanning, the internal integrity of these ancient wooden supports was examined. Stress wave analysis, pilot nail testing, and assessments of static bending and compressive mechanical performance were performed to validate and compare the data. The findings revealed substantial variability in the material quality across the columns’ cross-sections, suggesting a loss of mechanical integrity that renders them unsafe for habitation or public access. A comparison between the CT scan outcomes for the Masson’s pine columns and the stress wave data from the dismantled counterparts confirmed a marked degradation in their mechanical characteristics, rendering them unfit for use. The CT scan findings align with the pilot nail test results, both accurately pinpointing the condition and precise locations of defects within the columns. The static mechanical performance tests substantiated the precision and dependability of the CT scanning, pilot nail testing, and stress wave analysis in evaluating the wooden columns’ quality. This research aims to establish a scientific foundation for employing diverse non-destructive testing methods in the preservation and strengthening of traditional wooden structures, thereby safeguarding our cultural heritage.

Fiber-reinforced polymer (FRP) is an external reinforcement solution for wooden structures, where several studies have shown its efficiency in maintenance and design. This solution is not yet among the main topics of literature, although its importance justifies new research on this relevant topic for construction. This systematic literature review involves the FRP as reinforcement in wood-based columns, using Engineering Village and Web of Science databases and PRISMA protocol to follow the procedures and ensure the quality of sampling. Reinforcement dispositions and types of assessments were identified so that the literature synthesis can contribute to identifying behavior models. Different methods of reinforcement sizing studied by the literature were synthesized and detailed as to their respective uses. A positive correlation between the reinforcement index and the increasing the load capacity of timber columns were discussed and statistically analyzed.

Tannin-based biomass foam was prepared through a self-foaming process at room temperature. The material’s density, porosity, microstructure, mechanical properties, thermal stability, limiting oxygen index (LOI), brittleness, as well as water absorption and retention properties, were studied. Adding 2% bamboo fibers in varying forms did not affect the uniformity of the foam cells. The density, porosity, thermal stability, and LOI of the foam material remained largely unchanged. The compressive strength of the unmodified tannin foam was 0.043 MPa, while the addition of 2% bamboo fibers increased the compressive strength by 72%. Even when the effect of density was excluded, the specific compressive strength was enhanced by 60%. Additionally, brittleness, measured as the slagging percentage, was significantly reduced from 16.12% to 4.78%. The modified foam could absorb up to 26.5% of its weight in water, with excellent water retention capabilities of 78.1% after 120 h while retaining its structural integrity under intermittent wetting conditions, making it suitable for vertical greening applications. This demonstrates its suitability for vertical greening applications, where moisture exposure is frequent. In conclusion, the bamboo fiber-reinforced tannin-based foam exhibits excellent mechanical properties and superior water absorption and retention performance.

Molded pulp products (MPP) products can accommodate a variety of fiber types and additives, including agricultural residues. This work showed the industrial scale production of molded pulp food trays made of double lined kraft clipping fibers with the addition of pistachio shell (PS) powder at levels from 5 to 30 wt% and evaluated the mechanical and barrier properties of the trays. The PS powder used to make the trays was ground using an impact mill and a cryo mill to a D50 of approximately 50 microns. Tray compression strength was tested to simulate the wrapping of food trays with plastic wrap. Additionally, the tray material’s basis weight, thickness, density, tensile strength, short span compressive strength, and absorptiveness were determined. The results showed that compared to the control tray sample, the trays containing the cryo-milled pistachio powder had essentially the same engineering properties as the control trays without PS. For the trays made with the impact-milled powder, the tensile strength, bending resistance, and compressive strength increased relative to the control 11.3%, 6.2%, and 13.5%, respectively. The study demonstrates a method to evaluate the incorporation of alternative materials into pulp molded products.

This experiment aimed to test the effectiveness of four antifungal chemicals in controlling mold contamination in edible mushroom production. The antifungal chemicals were terbinafine hydrochloride, prochloraz, azoxystrobin, and sodium dichloroisocyanurate. The inhibitory effects of the chemicals were evaluated for inhibition on Cladosporium sp., Aspergillus niger, and Neurospora sp. The mycelia of the three molds and Morchella sextelata were cultured individually and co-cultured on plates with different concentrations of these chemicals, and then the mycelial growth was observed. By comparing the growth areas under the same conditions, the appropriate concentrations of each chemical were determined. The results indicated that terbinafine hydrochloride and prochloraz significantly inhibited the mycelial growth of all three mold species at certain concentrations, whereas their impact on the mycelial growth of M. sextelata was not significant. These results suggest that these two chemicals are effective in controlling the mycelial growth of the three molds, potentially increasing the yield and quality of M. sextelata and reducing mold contamination during storage and transportation.

The catalytic role of desulfurization fly ash (DFA) was explored as a means to upgrade biomass-derived pyrolysis gas, with a focus on integrating waste valorization and renewable energy production. Soybean straw (SS) was pyrolyzed with DFA to assess the influence on pyrolytic product distribution. The results indicate that DFA notably influenced the yield and quality of pyrolysis gas, with optimal yields achieved at specific DFA concentrations. The study also demonstrated that DFA enhanced the production of methane (CH₄) and hydrogen (H₂) while reducing carbon monoxide (CO), thereby improving the lower heating value of pyrolysis gas. Fourier-transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were employed to characterize the char, showing increased surface area and pore volume due to DFA addition. The study concluded that DFA is an effective catalyst in biomass gasification, providing valuable insights into its catalytic mechanisms and potential for industrial application.

Wood panel surface defect detection is critical to product quality. Traditional detection methods are time-consuming and subjective, and they can lead to economic waste, while deep learning image recognition techniques offer a new approach. However, the accuracy and convergence speed of existing defect detection techniques still require improvement. In this paper, an improved algorithm based on YOLOv8n was designed for accurate detection of wood panel defects. The C-ADown method was designed to replace traditional downsampling, while preserving high-frequency features. The combination of the Dilation-wise Residual Module and multi-scale dilation attention was employed to enhance the multiscale robustness of defect detection. A hybrid encoder was added to improve localization accuracy. The loss function was optimized to improve detection accuracy and convergence speed. Compared to the base YOLOv8 version, the improved model achieved a 6.1% increase in mAP, an 8% increase in recall, and a 3.6% increase in precision, significantly enhancing the model’s detection capabilities. The GitHub link to the improved algorithm files is as follows: (https://github.com/humblefactos1/YOLOV8-CDC/tree/main.)

The production of biomethane (Bio-CH₄) from dairy wastewater was evaluated using two types of reactors: an upflow anaerobic sludge blanket (UASB) reactor and a batch reactor, using dairy wastewater, anaerobic sludge (as inoculum), and Opuntia imbricata (as biomass substrate). The latter is a cactus known as coyonoxtle and is considered an invasive plant in northern Mexico. The wastewater was characterized in accordance with NOM-001-SEMARNAT-2021. The UASB reactor having a capacity of 4.5 L, was charged with 350 mL of sludge, 24 g of Opuntia imbricata, and 3.5 L of dairy wastewater (20.1 g/L of O₂) at pH 7.0. Batch reactors with a volume of 120 mL, were charged with 72 mL of dairy wastewater (20.1 g/L of O₂), 8 mL of sludge, and 3 pieces of O. imbricata. The results of the UASB reactor: Total specific production was 21.2 mmol of Bio-CH₄ and an efficiency in the degradation of organic matter of 70.7%, with a hydraulic retention time of 4.8 h and a total duration of 720 h. For the batch reactors: Total specific production was 11.6 mmol of Bio-CH₄ and 97.95% efficiency in the removal of organic matter, with a total duration of 192 h. The results showed an economic, efficient and sustainable way of producing Bio-CH₄.

Peels from Citrus sinensis and C. limon were used for the preparation of essential oils. The hydrodistilled citrus peels presented various compounds, including cyclohexene, 1-methyl-4-(1-methylethenyl)-, (S)- (91.8%) and 7-methyl-3-methylene-1,6-octadiene(3.40%). Compared with the essential oils isolated from C. limon, the C. sinensis essential oil showed maximum radical scavenging activity, with an IC₅₀ value of 4.31 µg/mL. Bacillus subtilis growth was generally inhibited by essential oils, and the zone of inhibition was 21 ± 1 mm, while the zone of inhibition was 20 ± 2 mm against Escherichia coli. The minimum inhibitory concentration ranged from 12 ± 1 to 128 ± 2.6 µg/mL. Similarly, essential oils presented lower minimum bactericidal concentrations against Bacillus subtilis, followed by Escherichia coli. The antimicrobial activity was tested using packed samples of fresh-cut guava fruit stored under refrigeration. The essential oil-treated guava fruit presented a decreased viable cell count. After 2 days of C. sinensis and C. limon essential oil treatment, the reduction in B. subtilis was approximately 1.7 log CFU/g compared with that of the control. In cut fruits treated with L. monocytogenes, the essential oils significantly reduced the bacterial population, and a 7 log CFU/g reduction was achieved after 8 days of treatment (p<0.05).