Volume 14 Issue 1

This study focused on the physical and chemical characterization of Chinese maize stalk leaf ash (MSLA) calcined at 500, 700, and 850 °C and MSLA residual leaching in aqueous solutions. The grain size distribution, chemical composition, and microstructure of MSLA were investigated using a laser Mastersizer, X-ray fluorescence, and scanning electron microscopy. The ash samples obtained before and after dissolving were analyzed using X-ray powder diffraction and X-ray photoelectron spectroscopy to identify the present minerals and observe the 2p atomic orbit of surface silicon and aluminum (Si 2p and Al 2p) transformation behaviors. The zeta potential and pH values of hybrid solutions were tested for various dissolving times. Silica was the predominant component observed in the MSLA. As dissolving time increased, the pH value gradually decreased, and the zeta potentials first slightly decreased and then remarkably increased. Quartz was identified in the MSLA. Another polymorphous crystalline form of silica, cristobalite, only appeared in the 850 °C sample. The binding energies of Si 2p and Al 2p shifted, which transformed the XPS peaks after the thermal and aqueous solution treatment of MSLA. These findings can be utilized to study the application potential of MSLA in cementing systems.

This work, for the first time, identified the phytochemical constituents of leaves, fruits, stem barks, and wood branches extracted from the tree pruning wastes of Leucaena leucocephala (Lam.) de Wit. grown in Egypt, showing 49, 29, 34, and 27 phytocomponents, respectively, as assayed by gas chromatograph-mass spectroscopy (GC-MS) analysis. The major components of leaves were 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester (17.7%), betulin (15.7%), lupeol (14.7%), androstan-17-one,3-ethyl-3-hydroxy-, (5à)- (12.3%), 9,12,15-octadecatrienoic acid, methyl ester, (Z,Z,Z)- (11.6%), betamethasone (9.7%), and β-sitosterol (9.1%). The major phytocomponents of fruits were β-sitosterol (55.7%), 3beta-hydroxy-5-cholen-24-oic acid (48.7%), 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester (42.9%), lupeol (29.3%), betulin (15.8%), stigmasterol (12.8%), and campesterol (7.6%). The major phytocomponents of stem barks were 1,2-benzenedicarboxylic acid, diisooctyl ester (65.7%), β-sitosterol (27.2%), betulin (22.1%), lupeol (21.1%), and 9,12-octadecadienoic acid (Z,Z)-, methyl ester (8.8%). Wood branches contained β-sitosterol (60.1%), 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester (47.2%), lupeol (22.5%), campesterol (15.6%), and stigmasterol (14.1%). Most of the identified compounds have been reported to possess important biological activities, such as antimicrobial, anti-inflammatory, anticancer, anti-arthritic, antioxidant, and antidiabetic activities. The four constituents of L. leucocephala were statistically independent in these phytocomponents. The phytocomponents in five solvents were mixed in describing the four constituents. These constituents of L. leucocephala are potential bioresources for phytopharmaceutics.

The objective was to identify yeast NG17, a newly isolated oleaginous yeast obtained from soil in Thailand and to characterize its oil yield and composition in sugarcane leaves hydrolysate (SLH), a sustainable resource. Biochemical and phylogenetic approaches were used to characterize yeast NG17, and its lipid content was determined by gas chromatography. Yeast NG17 was placed in the genus Candida, but not identified to species. It had an oil content of 27.9% (w/w, dry weight) with a major fatty acid composition of oleic (57.6%) and palmitic (25.4%) acids when grown in a high carbon/nitrogen (C/N) ratio medium for 6 d. The oil yield of Candida sp. NG17 was 2.3 g/L when grown in SLH, which contained 18.7 and 19.1 g/L glucose and xylose, respectively, without any supplementation. Meanwhile, the oleic and palmitic acid composition of the oil was reduced to 48.5% and 22.1%, respectively. The oil yield obtained in SLH was higher than that in the detoxified SLH (2.1 g/L). Increasing the SLH pH to 6.5 resulted in an increased oil yield to 5.07 g/L. Supplementation of SLH (pH 6.5) with 0.1% (w/v) KH₂PO₄ further increased the oil yield of Candida sp. NG17 to 6.67 g/L. Overall, Candida sp. NG17 is a good source of oil for renewable oleochemicals and biodiesel production.

A new method for wood identification using terahertz (THz) time-domain spectroscopy (TDS) is presented. THz-TDS technology is an emerging method of spectral analysis method that shows great advantages in wood non-destructive testing. Wood is opaque in the optical and near infrared spectrum, and relatively transparent in the THz band. In this experiment, four wood species (Pinus densiflora, Pinus sylvestris, Pseudotsuga menziesii, and Cunninghamia lanceolata) were selected as samples. Optical parameters such as absorption coefficient and refractive index of the measured samples can be extracted from THz time-domain spectra. Principal component analysis was introduced to reduce the dimensionality of the THz spectral data of the wood. The principal component score matrix of the wood was obtained and used as a characteristic matrix. A wood classification model was established using a support vector machine. The experimental results showed that THz-TDS had excellent performance in wood recognition. This research lays a theoretical and application foundation for the application of THz technology in the field of wood detection and recognition. It also provides a new direction and technical scheme in the wood identification field.

A strain of Bacillus bacteria, which was able to increase the molecular weight (M) of black liquor (BL) lignin through polymerization, enabling the subsequent industrial use of lignin, was isolated and characterized. This study is believed to be the first time that actual bacteria cells, rather than pure laccase, have been used to polymerize BL lignin. Black liquor is a toxic waste product from the pulp and paper industry that contains lignin. However, the M of lignin is too low for commercial use. The bacteria performed two processes. First, the bacteria produced laccase, which degraded lignin into low M aromatic compounds (LMWACs). Second, the laccase transformed the LMWACs into quinone intermediates, which polymerized and became high M lignin. Five bacterial strains were isolated from a pulp mill, and the best strain was selected. The optimum growing conditions and BL concentration were determined. The optimum growth conditions when using pure lignin were 1 g/L lignin, 5 g/L urea, and 35 °C. When using BL instead of pure lignin, the optimum concentration was 2% BL (v/v). This information could help develop effective industrial utilization of BL lignin.

The influence of acid hydrolysis conditions on cellulose nanowhiskers (CNW) made from moso bamboo (Phyllostachys edulis) was investigated in this study. Procedures with or without an alcohol–toluene extraction were tested using different acid concentrations and hydrolysis durations. The alcohol–toluene extract had no significant effect on the properties of bamboo cellulose nanowhiskers (BCNW). According to the results, a sulfuric acid concentration of 46% with 2 h of hydrolysis and a concentration of 55% with 1 h of hydrolysis were ideal for preparing BCNW because the product had a relatively high crystallinity index. In addition, the surface functional groups of the products obtained from different sulfuric acid hydrolysis conditions were similar. However, groups treated with lower acid concentrations exhibited slightly stronger thermal stability than those treated with higher acid concentrations.

Carbon microparticles were produced from different technical lignins, i.e., kraft lignin, soda lignin, lignosulfonate, and organosolv lignin, at different carbonisation temperatures (800 °C, 1200 °C, 1600 °C, and 2000 °C). Before carbonisation, oxidative thermostabilization was performed. The combination of thermostabilization and carbonisation led to a high mass loss and shrinkage, but no major effect on the particle morphology was apparent. The carbon particles obtained from all four lignin variants developed disordered graphitic structures at high carbonisation temperatures, and good electrical conductivities in the carbon powders were observed for all lignin variants, with the exception of lignosulfonate. The polycaprolactone composite films filled with 30% lignin-derived carbon exhibited various conductivities, with the best results achieved using the kraft lignin-derived carbon.

Injection molding is a widely used manufacturing process operation that generates polymer products. The selection of optimal injection molding process settings is essential due to the distinct influences of process parameters on polymeric material behavior and quality, particularly during the injection process. Therefore, it is vital to determine the optimized process parameters to enhance the mechanical properties of the products and ensure the most favorable performance. This paper examined the integration of Taguchi’s method with grey relational analysis (GRA) to determine the effects of varied injection molding parameters on the mechanical properties such as tensile strength and hardness values. The experiments were designed using Taguchi’s L9 orthogonal array after weighing in control factors, such as melting temperature, injection pressure, injection speed, and cooling time. The GRA revealed that the multiple responses correlation was successfully established. Finally, an analysis of variance was performed to validate the test outputs. The results revealed that the most influential factor was injection pressure, sequentially followed by melting temperature, cooling time, and injection speed.

Joints are used to join furniture parts, and they represent a critical part of the structure of furniture. The quality of joints is greatly affected by the accuracy of their execution. When designing furniture, it is important to carefully consider the type of joint used so that it can hold all the joined elements together. Under loading of the joined structures, internal forces develop, which can lead to failure of the joints. This study investigated the elastic stiffness of spruce (Picea abies L.) dowel joints. The effects of selected factors such as the type of loading (compressive versus tensile), the size of the dowels (one-half versus one-third of the thickness of the joined elements), the type of adhesive used (polyvinyl acetate versus polyurethane), and annual ring deflection were examined. Spruce dowel joints exhibited the highest elastic stiffness values with a higher-diameter dowel glued with PUR adhesives and subjected to compressive loading. The impact of annual rings was not a significant factor. Finally, the reference type joints were compared with other commonly used types, such as three types of mortise and tenon joints (simple, haunched, and dovetail).

The effect of ethylenediamine (EDA) treatment on cellulose nanofibers (CNFs) remains unclear. To study the effect of EDA treatment on the gelation of the fibrillated CNFs, hydrogels that received 1, 2, and 3 EDA-treatment/washing cycles were prepared and analyzed. Different concentrations of the EDA treatment were also used to prepare hydrogels. Both X-ray diffraction and Fourier transform infrared studies showed that cellulose I/II hybrid hydrogels were fabricated from CNFs via 2 or 3 cycles of 99 wt% EDA treatment and then were washed with water. Field emission scanning electron microscopy observations indicated that the obtained CNF-based hydrogels presented some aggregations via the coalescence of adjacent individual CNFs. Moreover, the hydrogel film with a cellulose I/II crystal structure showed a higher tensile strength of 2.4 MPa and a fracture strain of 23.5%. This was because it had an entangled continuous nanonetwork structure formed after repeated EDA treatment. The authors hope that this work can further stimulate interest in the development of CNF-based hydrogels with multiple structures, properties, and functions for a variety of applications.