Volume 17 Issue 2

Azolla filiculoides is an aquatic fern with the potential to become a source of raw materials in a biorefinery system, e.g., a source of soluble and insoluble carbohydrates, proteins, carotenoids, and polyphenols. The fiber chemical content was determined as cellulose (19.2% dry basis) and hemicellulose (7.6% dry basis) content. Azolla has no lignin as a cell wall structure material. Cellulase treatment showed no effect in ethanolic extraction, but polyphenols were found in the enzyme solution at the end of the reaction. The phenolic acids and flavonoids contents of those with health promoting activity were determined, with gallic, syringic, rosmarinic, and p-coumaric the most abundant acids; kaempferol, apigenin, and quercetin were the most abundant flavonoids. The results show that A. filiculoides is a valuable source of bioactive components and cellulosic materials.

Radial and between-clone variations in stress-wave velocity, air-dry density (AD), and mechanical properties in six clones of 5-year-old Acacia auriculiformis trees planted in Vietnam were investigated. The potential to predict modulus of elasticity (MOE) and modulus of rupture (MOR) using stress-wave velocity of standing trees (SWVT) or small specimens (SWVS) was also examined. The examined SWVT, SWVS, and wood properties differed significantly among clones, particularly with two (clones 1 and 6) well suited for A. auriculiformis tree breeding programs focusing on lumber production, as they had the highest static bending values and no significant difference in AD between positions near pith and bark. At the specimen level, the best prediction of static bending properties could be achieved when both SWVS and AD were used in a model for calculation of dynamic modulus of elasticity (MOEd) in air-dry conditions. Significant correlations between SWVT and average MOE (r = 0.83) and MOR (r = 0.61) of test specimens indicated that the use of stress-wave technique for assessing MOE and MOR for selecting the best A. auriculiformis clones in terms of lumber performance was possible.

Despite contributing almost RM 20 billion (USD 4.9 billion) in exports earnings annually, the public perception of the wood products industry in Malaysia remains unknown. Therefore, this study attempted to assess public perceptions about the industry in Malaysia among the public, including teenagers, based on 3,010 reliably answered questionnaire-surveys. Generally, the public perceived the wood products industry to be a low-wage economy, labor-intensive, predominated by foreign contract workers, and unsustainable in the long-term. In essence, the public appear to have stronger negative images of the industry compared to the positive images. The main drivers for such negative perceptions, identified through the factor analysis, were the prevailing business environment in the industry and its workforce characteristics. Consequently, teenagers and school-leavers tend to be less interested in pursuing a career in the industry, let alone pursuing further studies in the wood-related fields. The main reasons cited for this were the limited career growth opportunity due to the predomination of family-controlled small and medium-sized enterprises (SMEs) in the industry and the discouragements from family members and friends. The provision of reliable, timely, and transparent information is important to boost the public’s awareness and build positive beliefs and perception of the wood industry.

The mobility and the bioavailability of heavy metals in waste activated sludge were determined according to their total content and chemical speciation. A modified three-step sequential extraction procedure was used to determine the total content and metal speciation distribution pattern of various heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) pretreated at a temperature of 100 °C to 200 °C. It was found that the organics solubilization was enhanced at higher temperature, increased by 1.75, 183 and 3.03 folds over the soluble chemical oxygen demand (SCOD) at 100 °C. The total contents of Cd, Pb and Zn exceeded the threshold value established in GB/T standard 23486 (2009), as a function of pH, due to the pollution from the local nonferrous metals industry. For most cases, the impacts of thermal pretreatment on the species distribution were limited and obscure. Cr was the only element showing a potential risk of metal mobilization, such that its residual fraction shifted towards oxidizable fraction at higher treatment temperature. The speciation distribution pattern of Ni, Cr, Cu, and Zn showed potential risks of contamination due to their bioavailability, mobility, or toxicity.

The chemical and physical properties of steam-exploded pine chips were analyzed by varying the temperature (190 °C to 230 °C) and time (1.5 min to 20.0 min) of steam explosion at the same severity factor (Ro), i.e., 4.0. Then, their potential as a dietary fiber source was evaluated. Overall, the chemical properties, e.g., solid recovery, cellulose, hemicellulose, and total dietary fiber content, showed a tendency to decrease as the temperature increased as well as an increasing lignin content. The physical properties, e.g., water-holding capacity, oil-holding capacity, and swelling capacity, showed decreased values in pine chips subjected to steam explosion at a temperature of 210 °C or greater. The chemical and physical properties of the steam-exploded pine chips, which were subjected to steam explosion at different temperatures and times at the selected Ro) considerably changed, starting at a temperature of 200 °C for 11.5 min. Even with the same severity factor, the steam-exploded pine chips at a temperature of 200 °C for 11.5 min showed the greatest improvement in the physical properties, i.e., water holding capacity (8.3 g/g), oil holding capacity (6.8 g/g), and swelling capacity (4.9 mL/g).

This study aimed to design and evaluate the detachable corner joints used in wooden furniture frames, including a commonly used detachable joint (control) form using mortise and tenon with plug reinforcement and three novel proposed joints, i.e., novel joint I ~ III, which adopted in-line double-hole nuts, metal sheet connector, and embedded nuts and screws respectively, via numerical and experimental methods. The numerical analysis results indicated that the optimal proposed joint (novel joint І) had good mechanical performance when subjected to bending load with proper stress distributions and relatively low maximum stress compared with the other two proposed joints. The experimental results showed that the bending load resistance of the control and the optimal proposed joints were 1920 N (0.14) and 4390 N (0.05), respectively. The bending moment capacity and bending stiffness of the optimal joints were remarkably higher than the bending moment capacity and bending stiffness of the control joint. In addition, the combination of the numerical and experimental methods could effectively simplify the steps of furniture connection design and development and save costs in terms of time and materials.

The current study was conducted to identify the most important variables in the activation phase of cellulose acetate production. Dry alpha cellulose pulp as raw material was supplied by a local company with the intrinsic properties of viscosity equal to 926 mL/g and a water content of 96%. In this regard, the activation phase variables, including reaction time (T30, T60, and T90 min), the addition level of acetic acid (C25, C35, and C45 units per 100 units of dry cellulose), and sulfuric acid catalyst (H0, H0.1, H0.5, and H1%), were experimented followed by characterization of the activated pulp properties through water retention value (WRV), carboxyl groups, viscosity, reactivity, and Fourier transform infrared (FTIR) spectroscopy analysis of fibers. The results indicated that cellulose activation is a complex process with an inverse or contributing effect of the variables. The data were extensively discussed considering the swelling effects governed by diffusion and chemical reactions in both crystalline and amorphous regions of fibers. Eventually, those findings conveyed that the activation process with the above-mentioned conditions was able to improve the properties of cellulose for acetylation phase particularly by increasing reaction time in acid acetic and H2SO4 catalyst consumption.

Bio-oils obtained from southern yellow pine biomass from two thermochemical conversion processes, fast pyrolysis (FP) and hydrothermal liquefaction (HTL), were investigated. The effects of FP and HTL on the physical and chemical properties of the bio-oils were characterized. The HTL and FP bio-oil yields were 67 and 36 wt%, respectively. The results indicated that the physical properties of the HTL bio-oil and FP bio-oil were similar; however, there were variations in the composition of the bio-oils from the same biomass. The pH values of the FP and HTL bio-oils were 2.3 and 2.8, respectively. From the GC-MS (gas chromatography–mass spectrometry) analysis, esterified chemical compounds were prevalent in the HTL bio-oil, while phenols and phenolic derivatives were found in both bio-oils. The 31P-NMR (phosphorous nuclear magnetic resonance) analysis of the bio-oils further revealed that both FP and HTL bio-oils are rich in phenolic OH and aliphatic OH functionalities, which could serve as a potential bio-polyol.

To reveal the mechanistic role of vibration in the compression of alfalfa stalk, the stress transfer of alfalfa compression process under the action of vibration force field was evaluated with a self-developed vibration compression test system. The internal stress in the upper layer of the compressed material was gradually transmitted to the lower layer. The stress transfer rate between the upper and lower material varied with the vibration frequency. Within the experimental vibration frequency range, when the frequency was 15 Hz, the stress transfer rate was the smallest. Compared with ordinary compression, the stress transfer rate and maximum pressure during vibration compression were small, but the relaxation density was high, indicating that vibration is beneficial to alfalfa compression. Comprehensive analysis of stress transfer, maximum pressure and relaxation density, when the vibration with vibration amplitude of 0.5 mm and frequency of 15 Hz was introduced, a denser alfalfa block was obtained with less pressure.

Because of their lower environmental impact, biodegradable polymers such as polyhydroxyalkanoates (PHAs) produced within cultured bacteria represent promising alternatives to petroleum-based plastics. PHA production in flasks yielded optimal results with a carbon-to-nitrogen ratio of 22. The 5-L scale experimental results revealed that when glucose was used as the carbon source, Cupriavidus necator could produce 4.74 g/L PHA with 77.6% of PHA content in the microorganism 72 h after the initiation of the experiment. When the hydrolysis liquid from inedible rice was used as the carbon source, the highest concentration of PHA and ratio of PHA content in the microorganism were 4.82 g/L and 68.6%, respectively, after 72 h. Using the hydrolysis liquid from inedible rice as the carbon source reduced the culture cost and shortened the culture time, without affecting the structure of the PHA during production. Using the hydrolysis liquid from rice as the carbon source in PHA production (by C. necator) yielded optimal results, and the results may serve as a reference for applications involving other PHA-producing bacteria. Employing alternative carbon sources to culture bacteria might become a means of increasing the productivity and ensuring the quality of PHA products in the future.