Volume 16 Issue 1

This work verified the direct measuring method of the contact force and its relaxation behavior between mortise and tenon joints through withdrawal load resistance testing of T-shaped mortise-and-tenon joint specimens. Further, it also studied the influence of wood species, beech (Fagus orientalis Lipsky) and Mongolian Scots pine (Pinus sylvestris var. mongolica), interference fitness (0.1, 0.2, 0.3, and 0.4 mm; 0.2, 0.4, 0.6, and 0.8 mm), and wood grain orientation (radial, diagonal, and tangential) on the contact force and its relaxation. The results showed that the direct measuring method had good feasibility for measuring the contact force and its relaxation of the beech and it showed good feasibility on measuring initial contact force of pine. However, it showed low feasibility for measuring the relaxed contact force when the interference was 0.2 mm, but showed good feasibility on measuring the relaxed contact force with larger interference of pine. Interference fitness, wood grain orientation, and wood species had a significant effect on initial contact force and contact force after 5 h relaxation. This study showed feasibility and application scope of the method for direct measuring contact force and provided additional fundamental data to contribute to further study of the internal mechanical mechanism of mortise and tenon joints.

A new type of polydimethylsiloxane-based paper transparentizing agent was prepared via a combined method. The performance of the transparentizing agent was investigated systematically by adding and dipping, with use of the surface sizing device of a paper machine. Optimum performance was found at 30% concentration of the transparentizing agent and 30 to 45 °C of dipping temperature. Under the optimal conditions, the transparentizing t agent achieved a rapid penetration in the base paper and filled in the pores of the paper, to be further effectively adsorbed and retained on the fiber surface. The transparency of test paper reached as high as 76±0.97 %, which was 37±1.4% higher than that of the control. However, the addition of transparentizing agent reduced the mechanical strength of paper slightly. The as-prepared transparentizing agent was found to exhibit excellent application stability and biodegradability when applied in the paper machine，When used as plastic film, the transparent paper would lose its strength completely after eight weeks. The resulting transparent paper can be used to develop paper-based film and other related plant based transparent/ translucent paper, which has great potential in replacing plastic products and eliminating white pollution.

Aspergillus flavus was used to produce alkaline protease. Solid state fermentation (SSF) strategy was adopted to explore the most favorable physical and nutritional conditions for enzyme production. Maximum production was achieved at pH 6.0 and a temperature of 30 °C after 84 h of growth period. For the optimization of the chemical parameters, different carbon and nitrogen sources were used including glucose, fructose, sucrose, ammonium sulphate, and urea. Maximum production was observed with 0.3% concentration of all the compounds. Ammonium sulphate salting out and gel chromatography was used to purify the enzyme. The enzyme was completely precipitated out at 80% saturation. The value of Vmax was 3.9 U/mL, while the value of Km was 1.9 mg/mL. The enzyme was tested for its compatibility with a few famous detergents available on the market. With the alkaline protease under study, the enzyme displayed a maximum retention of its activity i.e. 80.8% in the presence of commercial detergent Surf excel. The activity dropped down to 61.5% when the enzyme was allowed to work in the presence of another locally used detergent, i.e., Bonus. Protease production from A. flavus was carried out on rice bran and wheat bran and the wheat bran gave better results.

Darwin stringybark (Eucalyptus tetrodonta) is one of Northern Australia’s most important commercial forest resources. The wood exhibits desirable wood properties including high strength, natural durability, and visual appeal. The production of engineered wood products (EWPs) such as glulam from this resource represents a significant commercial opportunity for the timber industry in northern Australia. However, a major challenge to overcome is the achievement of satisfactory glue bond performance. This study evaluated the effects of different surface machining preparations, adhesive types, and curing temperatures on the bonding characteristics of Darwin stringybark. The pre-gluing surface machining method significantly influenced the timber wettability, roughness, permeability and tensile shear strength of adhesive bonds. Planing resulted in the lowest wettability, roughness, and permeability, while bonded planed samples produced the poorest tensile shear strength. Alternative surface machining methods including face milling and sanding post-planing were shown to significantly improve the timber wettability, roughness, and permeability, and also to increase the tensile shear strength of bonded samples. The resorcinol formaldehyde adhesive resulted in slightly improved tensile shear strength in most cases compared to the polyurethane adhesive. There was no significant improvement in tensile shear strength with the use of elevated temperature curing.

Acicular mesoporous char sulfonic acid was prepared through a one-step method of removing the template at the same time of sulfonation using ethylene tar (ET) as the carbon source and acicular nanometer magnesium hydroxide as the hard template. This method was judged as better than the two-step method of removing the template before sulfonation because it protected the mesoporous structure from damage to a certain extent. When the mass ratio of ET to Mg(OH)2 was 1:3 and carbonization temperature was 550 °C, the catalyst prepared using the one-step method had the highest activity. The obtained catalyst had an amorphous structure with a specific surface area of 446.5 m2/g, an acid density of 4.68 mmol/g, and an average pore diameter of 3.5 nm. When the catalyst was applied in the dehydration of fructose to synthesize 5-hydroxymethylfurfural (5-HMF), 97.5% fructose conversion and 80.1% 5-HMF yield can be obtained. The activity of the catalyst did not decrease after 5 cycles, which indicated that the catalyst had good stability. This research provides a promising strategy for preparation of mesoporous char sulfonic acid and comprehensive utilization of ET.

The furniture sector has a strategic importance in Turkey. That sector contributes greatly to the national economy, provides high levels of employment, is rapidly growing, and does not have a foreign trade deficit. In this paper, a hybrid multi-criteria decision-making method was used to determine the contribution of some furniture products to Turkey’s economy. First, the entropy method was used to determine the weight values of the criteria, and then the ELimination Et Choix Traduisant la REalité (ELimination Et Choice Translating REality) (ELECTRE) method was used to compare and rank the alternatives. As a result of this analysis, the furniture products that contributed the most to the national economy were “seating furniture and parts thereof, other wooden furniture”, “wooden bedroom furniture”, “other metal furniture”, and “parts of furniture other than metal and wood”. The least contributing products were “furniture used in medicine, surgical, dental, veterinary, and barber chairs etc.”, “plastic furniture”, and “furniture other than metal, wood, and plastic”.

This study examined the racking performance of poplar laminated veneer lumber (LVL) frames using bolted steel filling plates to connect beam-column joints, poplar LVL frames using the embedment bars to connect beam-column joints, and frame-shear hybrid walls made of poplar LVL studs and oriented strand board (OSB) sheathing panels. A new design load spreader beam was used on the side of the top of a specimen to apply monotonic and cyclic loadings. It was found that the lateral force resistance, stiffness, and ultimate loads of poplar LVL pure frames with bolted steel filling plate connections and closed rod connections were much lower than those of the poplar LVL frame-shear wall hybrid structure. The highest initial stiffness of the poplar LVL hybrid frame-shear wall was 1.77 kN/mm, which was 24% and 22% lower than that of the conventional shear wall made with spruce-pine-fir studs and OSB or plywood sheathing panels, respectively. The poplar LVL frame-shear wall hybrid structure showed lower degradation in stiffness than the conventional shear wall. The hybrid frame-shear wall structures made of poplar LVL could meet the requirements of Chinese standard; however, diagonal braces were required in use of poplar LVL pure frames.

Construction of eco-friendly high-rise buildings using cross-laminated timber (CLT)-concrete composite (CCC) slabs is increasing. CLT and concrete, which are major component materials of the CCC slab, are significantly affected by moisture. In particular, the moisture content of concrete in the production process affects the quality of both materials. In this study, the effects of the wet construction method on CLT and concrete component materials are examined by monitoring the behavior of the CCC slab during curing time (28 d) and by evaluating the quality of the concrete and CLT after curing. When manufacturing the CCC using the wet construction method, moisture penetration from the concrete into the CLT during the curing time is suppressed by the shear bonding between the concrete and the CLT when an adhesive is used. This minimizes the effect of the moisture on both component materials, consequently yielding uniform compressive strength to the concrete after curing and preventing the deterioration of the CLT’s delamination performance. Therefore, the shear bonding method using an adhesive is expected to minimize the quality deterioration observed in concrete and CLT after curing.

Despite bamboo’s noteworthy durability, the incidental effects of smoke treatment on the mechanical properties of bamboo culms, including its underlying mechanisms, have not been fully investigated. This study investigated the effects of smoke treatment on the flexural strength of Madake bamboo’s (Phyllostachys bambusoides) hierarchical structure. Results in small clear specimens displayed an asymmetrical flexural behaviour regardless of the applied treatment, and the parameters of flexural strain and specific energy absorption, demonstrated by modulus of elasticity and modulus of rupture, were found to differ. Concerning compression, parenchyma cells had good ability to absorb large deformation, indicated by their large increase in specific energy absorption. In addition, a distinct difference was found between smoke-treated bamboo and untreated bamboo as the capacity of its outermost fibres to withstand greater tensile load was impaired, indicated by the reduction in flexural strain. Thermal degradation caused an increase in the hydrophobicity of bamboo’s outermost layers, thereby engendering higher brittleness in the smoked bamboo. This work highlights critical changes in the mechanical properties of smoked bamboo, which can be addressed in future studies to improve its strength as a sustainable construction material.

Wood Science and Technology (WST) courses have been traditionally taught face-to-face in most of the universities worldwide, but the global COVID-19 pandemic has disrupted classroom lessons, replacing them with online teaching and learning methods. To assess the effectiveness of these online methods, a survey of students and academics were carried out in several Malaysian universities offering the WST programs. The survey revealed that students were mostly challenged by the problems related to access to internet, computer hardware, and lack of communication. Further, the student-centered learning method was preferred, while non-technical courses were the most suited for online teaching and learning. In contrast, academics appear to prefer pre-recorded lectures and recorded videos as the most common method for teaching online, while continuous assessment of the student’s progress found limited application. The results found that to enhance the effectiveness of teaching and learning online of WST courses, factors such as connectivity, student’s preparedness, content design, pedagogical approach, peer communication, and the teacher’s presence, must be taken into consideration and improved.