Volume 20 Issue 1

In recent years, lignin analysis utilizing quantitative nuclear magnetic resonance (qNMR) has attracted considerable interest and has been the subject of numerous studies. However, evaluating the measurement uncertainty of qNMR results of lignin remains a challenge. Specifically, uncertainty originating from lignin sampling or subsampling has been overlooked in a large majority of articles. Although lignin is a reasonably homogeneous substance, it is nevertheless a solid, and individual samples collected from the same bulk may have somewhat different compositions depending on mixing and the amount of sample taken. The objective of this study was to evaluate the influence of sampling uncertainty on qNMR analysis of lignin-based analysis as a case study, with an exclusive focus on the relative quantification method. The results from this study demonstrate that sample-to-sample variations can contribute to approximately half of the variability in actual qNMR measurements. The relative standard deviation (RSD) of sample-to-sample variability was 2.4%. In contrast, the other sources of variability related to qNMR, including measurement, baseline irregularities, and partial peak overlap, caused an RSD of 4.4%. The total variability RSD was 5.0%. In this article, two calculation approaches were presented for evaluating the uncertainty due to sampling from replicate measurement data of different samples, which may be helpful for practitioners in the field.

The effect of alkali lignin on laccase activity and mycelial biomass of Flammulina velutipes was investigated under different fermentation temperature. The secretion of laccase by F. velutipes has certain specificity. Specifically, laccase activity could not be detected by F. velutipes CCMSSC 00103 under most fermentation medium, but could be detected by F. velutipes FL 19 under more fermentation medium. Among the three strains of F. velutipes, the laccase secretion capacity of F. velutipes FL 19 was obviously better than that of F. velutipes CCMSSC 05331 and F. velutipes CCMSSC 00103. Maximum laccase activity with the value of 73.42 ± 4.74 U/L was secreted by F. velutipes FL 19 in fermentation medium 2 appeared at 2th day. The presence of alkali lignin was useful for improving laccase activity secreted by F. velutipes and the effect of alkali lignin on improving laccase activity exceeded that of Populus beijingensis. F. velutipes were more suitable for secreting laccase at 26 ℃ due to the maximum laccase activity measured at 26 ℃ (73.42 ± 4.74 U/L) higher than that measured at 33 ℃ (70.71 ± 6.89 U/L). The results were useful for selecting suitable medium and temperature of F. velutipes strains to produce low-cost laccase.

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.

Bamboo is a sustainable material that supports carbon sequestration and helps address the imbalance of timber supply vs. demand. Drying is a crucial step in bamboo processing, in the course of which shrinkage and stress accumulation can lead to defects such as cracking and deformation. Understanding stress and strain development during drying is critical for improving bamboo processing. This review paper explores bamboo’s gradient structure and moisture migration characteristics, focusing on the mechanisms behind shrinkage strain formation and the sources of stress. It reviews literature on bamboo drying and cellular structural changes, evaluating the evolution of stress and strain testing methods, from traditional sectioning techniques to advanced methods such as digital imaging and acoustic emission. The paper also summarizes progress in stress-strain research at both macroscopic and cellular scales. Current challenges include species-specific shrinkage variations, limitations in measurement techniques, and insufficient research on shrinkage above the fiber saturation point. To address these issues, the study recommends developing universal theoretical models, employing advanced detection technologies, comparing shrinkage patterns between bamboo culms and nodes, exploring drying stress composition, and adopting multi-scale research approaches. These strategies aim to enhance the quality of bamboo processing and promote higher-value applications within the industry.

In recent years, the process of optimizing the design of natural fiber reinforcement in natural fiber composites (NFCs) with distinct properties has been redefined through the application of machine learning (ML). This work elucidates the functions of the types and applications of the ML algorithms and evolutionary computing techniques, with a particular focus on their applicability within the domain of NFCs. Moreover, the solution methodologies and associated databases were employed throughout various stages of the product development journey, from the raw material selection through the final end-use application for the NFCs. The strengths and limitations of the ML in the NFCs industry, together with relevant challenges, such as interpretability of ML models, in materials science was detailed. Finally, future directions and emerging trends in the ML are discussed.

Pinus trees are widely distributed worldwide, and pine needles, pine bark, pinecones, etc., have potential medicinal value. This paper reviews the medicinal potential of extracts from different organs of three trees of the genus Pinus in East Asia. Studies have shown that pine trees are rich in bioactive compounds, and these compounds have a variety of pharmacological activities, including antioxidation, anti-inflammatory, antibacterial, antitumor, and hypolipidemic effects. The wide range of pharmacological activities of these bioactive components is helpful for the treatment of cardiovascular diseases, inflammatory diseases, tumors, and other diseases. These findings can help promote research on the medicinal potential of Pinus and its organs to realize the efficient utilization of byproducts of pine resources.

Timber-concrete composite (TCC) beams are formed by integrating timber beams and concrete slabs into a cohesive structural unit using shear connectors. This integration capitalizes on the tensile strength of timber and the compressive strength of concrete, resulting in excellent load-bearing capacity, bending stiffness, vibration comfort, sound insulation, and fire resistance. The long-term behavior of TCC beams must be emphasized, considering the significant time-dependent behaviors of timber, concrete, and the connection system. This work analyzed the long-term mechanical behavior of TCC beams and systematically reviewed the current research on the long-term performance. The primary focus was on the experimental studies of the shear performance of the shear connectors and the mechanical performance of TCC beams under long-term loads. Furthermore, theoretical methods and numerical simulation analyses for evaluating the long-term performance of TCC beams were analyzed. Strengths and weaknesses of existing theoretical methods are identified, and further research and development in the calculation method of TCC beams under long-term loads is proposed.