Volume 14 Issue 2

Field retting is an industrial process for extracting valuable bast fibres from hemp. In this study, molecular, chemical, and scanning electron microscopy studies were employed to understand the field retting mechanisms involving microbiota, including microbial community dynamics, hemp colonization, functions/interactions, and hemp biodegradation. This study for the first time revealed the coexistence of bacterial-fungal interactions during retting and showed progressive microbial breakdown of the stems. Using scanning electron microscopy, evidence for microbial activities/interactions within the stems was obtained, which helped to understand hemp retting mechanisms. The collective findings showed that: a) initially, easily accessible food within the hemp stems attracted and supported microbial invasion and decay, with activities influenced by the stem anatomy, chemistry, and morphology; b) filamentous fungi as key players in the early stages remarkably contributed to efficient fibre defibration; c) extended retting enhanced the bacterial activities, including bacterial-fungal interactions and their dominant role within the community; d) bacterial attraction and activities were promoted by bacterial mycophagy with a set of different phenotypic behaviours for nutrients and fungal highways for transport within the stems; and e) bast fibre degradation leading to inferior quality during prolonged retting was caused by ultrastructural modifications to all of the major fibre cell wall layers.

Close inspection of black cherry (Prunus serotina), sugar maple (Acer saccharum), and northern red oak (Quercus rubra) lumber, before and after kiln drying, revealed the factors that can affect the quality of kiln-dried lumber from small-diameter logs. Species-specific kiln drying schedules, with temperature and humidity modifications formulated by a kiln drying expert, were employed in this study to determine whether alternate drying protocols could improve the drying outcomes. Comparing lumber grades of individual boards before and after drying indicated that overall grade loss in the kiln was common but was affected by both species and the applied drying schedule. Most lumber defects were attributed to stresses that occurred during the drying process and were more prevalent in the post-drying inspection, with bow defects being the exception. The modified kiln schedules improved the drying defect outcomes for the black cherry and red oak compared with the conventional schedules for these species. For the sugar maple, the schedule-based improvement was less consistent. For the black cherry and red oak, the percentage of boards whose grade decreased using conventional kiln protocols was approximately 10% lower than that of the lumber that was dried using the modified kiln protocols. Sugar maple had a smaller change of 7%.

Sendan (Melia azedarach), a domestic fast-growing species in Japan, was used as a material of particle board (PB). Sendan lumber was crushed into chips using a hammer mill, and PB was made of these chips with p-MDI adhesive. For a reference, recycled chips including softwood were also used for a fabrication of PB. The mechanical properties of PB and the biological performance of solid wood and PB were investigated. Bending strength, internal bonding strength, and thickness swelling were evaluated for mechanical properties of PB, meeting the Japanese industrial standard (JAS). For the biological performance tests, solid woods of sendan and sugi were used. Termite resistance and decay resistance of both the solid woods and the PBs were evaluated. The mechanical properties of sendan and recycled PBs met the criteria of JAS. A white-rot jungus, Trametes versicolor decayed sendan heartwood and sendan PB more easily than sugi heartwood and recycled (softwood) PB, respectively. The termite resistance of sendan heartwood and sendan PB was superior to that of sugi heartwood and recycled PB, respectively. The higher density and the solvent removal of extractives in sendan heartwood were likely to be responsible for their high termite resistance.

Chuzu Temple is one of the buildings in the historical architectural complex in “The Center of Heaven and Earth” in Dengfeng County. It is more than 800 years old. Currently, various kinds of damage can be found in the Chuzu Temple main hall. For more applicable conservation and renovation of the building, the status of the dougong (斗拱) under the external eaves of the Chuzu Temple main hall was investigated. Additionally, the existing types of damage and their causes were statistically analyzed to provide a practical reference for structural performance evaluations and protection reinforcement of the extant structure. According to the investigation results, 50.8% of the dougong members under the external eaves of the main hall had different types of damage. The main types of damage included detachment, plucking, holes, cracking, crushing, separation, and missing parts. The main causes were mechanical damage, bioerosion, and material degradation. Additionally, the study revealed that Larix sp., Ulmus sp., Quercus sp., and Populus sp. were the wood species used in the restoration to replace the antiquated wood.

Lignocellulose biomass plays an important role in reducing the dependency on fossil fuels and ameliorating the dire consequences of climate change. It is therefore important that all the components of lignocellulose biomass are exploited. These components include hemicelluloses and extractives that are liberated and sterically stabilized during the thermomechanical pulping and that form the dissolved and colloidal substance (DCS) in the process water. Biorefining of this process water can extract these substances, which have a number of promising applications and can contribute to the full exploitation of lignocellulose biomass. This paper presents a simple treatment of unbleached Norway spruce (Picea abies) process water from TMP (thermomechanical pulping) production using induced air flotation (IAF) and cationic surfactant, dodecyl trimethylammonium chloride (DoTAC) to refine the extractives and prepare the waters so that hemicellulose could be easily harvested at a later stage. By applying 80 ppm of DoTAC at a pH of 3.5 and 50 °C before induced air flotation, 94% of the lipophilic extractives were recovered from process water. Dissolved hemicellulose polysaccharides were cleansed and left in the treated process water. The process enabled efficient biorefining of lipophilic extractives and purification of the process water to enable more selective harvesting of hemicelluloses in subsequent steps.

Deformation behavior is an important fundamental characteristic of lignocellulosic fibers; it affects the application range of fiber materials and the properties of fiber-based products. For instance, the density of a paper sheet depends on the degree to which the wet fibers are able to conform to the shapes of adjacent fibers during pressing and drying. In this study, a model for revealing the contribution of inherent characteristics of lignocellulosic fiber to its deformation behavior was developed and compared with other general models. The response sensitivities of cross-sectional parameters, fiber cell wall composition, and structure to the deformation behavior were determined as 3.26, 0.26, and 0.06, respectively. The results showed that the cross-sectional geometry was the main contributor to the deformation behavior of lignocellulosic fibers, followed by the ratio of different fiber cell wall components, and the fiber cell wall structure. To develop a comprehensive understanding of fiber separation in industrial production, the inherent fiber properties contributing to deformation behavior were investigated. This data could guide manufacturers to manage the treatment of different fiber separation processes to obtain fibers with required deformability, and thereby meet the requirements of fiber-based products.

The antioxidant activity and the tocopherol and polyphenol contents of organic grapevines residue were analyzed after Soxhlet extraction of grape seeds and skin with ethanol and petroleum ether. The highest antioxidant activity was determined for the ethanol extract of the seeds and was 58.65 μM Trolox/mg, which was four times higher than for the ethanol extract of the skin at 14.24 μM Trolox/mg. It was comparable to that of the alpha-tocopherol (62.28 μM Trolox/mg) and butylated hydroxyanizol (69.55 μM Trolox/mg). A concentration of 29.5 μg/mL ethanol seed extract was needed to decrease the initial DPPH radical concentration by 50%. The high antioxidant activity was because of the high tocopherol (402.28 mg/kg) and total phenols contents (113.7 gallic acid equivalent (g/kg)) in the seeds. The dominant polyphenol in the ethanol seed extract was coumaric acid (10.97 g/kg). The dominant polyphenols in the ethanol skin extracts were rutin (6.79 g/kg), quercetin (3.75 g/kg), and catechin (3.99 g/kg), which can be used in functional foods to reduce risk factors for several human diseases.

The increase in fatal road accidents, natural disasters, and even terrorist attacks around the world have contributed to the improvement of public security. Windows can be particularly hazardous because of cutting fragments expelled during breakage or an explosion, which may induce injury. It is becoming essential to develop a resistant daily security glazing for houses to prevent damage in earthquakes and tornado areas, for utility cars, etc. Nanocellulose was used, which has a low ecological footprint, to improve safety glazing properties and was based on poly (vinyl butyral) (PVB). Following the processing of many different recipes for layers based on both PVB and nanocellulose polymers, intercalary films were assembled with glass using hot pressing. The results of the three-point bending experiments were promising. Breaking loads were approximately 8000 N for the two nanocellulose samples, which were close to the results of the sample with PVB only. Furthermore, the obtained composites possessed a transparency near that of PVB only. Finally, nanocellulose overtop PVB had a surface mass as low as one eighth of that of the PVB.

This study focused on the effect of an extractive treatment and the application of citric acid on the properties of particleboard made from Salacca frond. In general, extractives have a negative effect on the bondability of synthetic resin. However, the effect of extractives on the bonding mechanism of citric acid as the biobased adhesive is unclear. Unextracted and extracted Salacca frond were used as the raw materials. A hot water extractive treatment was conducted by boiling the particles for 2 h. The boards were manufactured under the following conditions: citric acid content of 0%; 10%; 20% weight percent (wt%), pressing temperature of 180 °C, and pressing time of 10 min. The target density was set at 0.8 g cm-3. The results showed that the addition of citric acid resulted in an increase in the physical and mechanical properties of the particleboard. Interestingly, when a 20% citric acid content was applied, there were no siginificant differences in the physical or mechanical properties of the particleboards made from unextracted and extracted particles. Based on these results, it was concluded that when citric acid is used as adhesive, the hot-water extractive treatment of Salacca frond is not needed.

In the competitive market, many furniture manufacturers are improving their process efficiency, eliminating unnecessary costs, and improving quality by using wood-based composite panels in frames. Currently, upholstery furniture frames are made by using over 70% wood-based composite panels, which causes material utilization to be the most important area of improvement. Many furniture manufacturers have realized that increased design and production efficiencies using wood-based panel products as their frame stocks combined with computer numerical control (CNC) technology is beneficial for the manufacturing process. However, manufacturers are continuously looking for alternatives to improve the bottom line of the manufacturing process, which includes optimization of the assumed panel width to maximize the cutting yield. In this case study, the effects of increasing the width of full-size wood-based composite panel products (1219-mm-wide × 2438-mm-long) on the cutting yield of parts for two upholstered frame models were investigated using computer simulation software with an optimization capacity. The results of the simulation indicated that increasing the width of the full-size wood-based composite panel products to 1371 mm and 1524 mm could yield better material cutting yields compared with the 1219-mm-wide panel products.