Research Articles

Waste tires represent an important source of polymer waste. The ground tire rubber derived from waste tires is a recycled product that can be combined with polystyrene (PS) to produce high-performance PS and waste rubber composites. To improve composite material performance, surface grafting modification of waste tire rubber with styrene to enhance properties of PS composites as a novel approach was investigated. The surface morphology and structure of polystyrene grafted waste tire rubber powder via a conventional free radical polymerization were confirmed successfully using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy analyses in addition to the Fourier-transform infrared spectroscopy (FTIR). The comparative mechanical and thermal property analysis of PS sustainable composites with recycling waste tire rubber powder with and without surface grafting modifications indicated an approximate 4-fold increase in the impact strength of polystyrene grafted waste tire rubber reinforced PS sustainable composites in addition to enhanced interfacial miscibility. The development of sustainable composite materials from recycled waste tire provides a novel avenue to achieve close-loop polymer recycling, which is of significance in the development of the circular economy and an environmentally friendly society.

Glycol lignin (GL) produced via acidic solvolysis of cedar wood meal with polyethylene glycol (PEG) is a highly functional material. In this study, the effects of wood meal particle size and amount of PEG added on the properties of PEG400-modified GLs (GL400s) were examined. For this purpose, cedar wood meal with four different particle sizes ranging between 0.18 and 2.00 mm and PEG400 at liquid ratios of 5 and 3 with respect to the wood meal were used. Acidic solvolysis at 140 °C successfully decreased the amount of solid residue with increasing GL400 yield and reaction time at both liquid ratios of 5 and 3. Overall, wood meal size remarkably affected the physical properties of GL400s at low PEG400 content (liquid ratio 3). In addition, the glass transition temperature T_g and thermal flow temperature T_f increased with decreasing wood meal size. Consequently, GL400s with varying thermal properties (T_g = 63 to 97 °C, T_f = 109 to 149 °C) were successfully prepared by adjusting the PEG400 liquid ratios and wood meal size. The data will support the development of a stable manufacturing process for the mass production of GL.

Rice straw lignin (LRS) tends to be dark in color, which makes it less appealing for material applications. Therefore, a bleaching process involving lignin oxidation is of interest. This study aimed to investigate the mechanical and chemical properties of bleached LRS and explore its potential application in PU-based paper coatings. LRS and commercial lignin (LC) were subjected to bleaching using 29% H₂O₂ through oxidation treatment. The bleached lignin was then used to prepare PU-based paper coatings. The effects of bleaching treatment on the functional groups, structural, and thermal properties of lignin, as well as the water resistance of the PU composites were assessed. The oxidation treatment resulted in a reduction in the phenolic hydroxyl content, methoxy content, antioxidant activity, and equivalent weight of lignin. However, LRS exhibited greater thermal resistance than did LC. The bleached LRS was successfully integrated with toluene di-isocyanate (TDI) to produce transparent polyurethane. This polyurethane was then applied as a coating for paper containers, which successfully held cold water for over 4 h without leaking, indicating its outstanding water repellency.

The ‘Malay’ rebab is a vertical, strung chordophone played similarly to a cello. The rebab strings sit on a bridge. The bridge is placed on a buffalo intestine on the front face. The buffalo intestine surface is pressed by the bridge in such a way that the string tension is not in a fully stable position. A ball of beeswax attached near the bridge mutes the sound reverberations. This investigation was undertaken by analyzing the rebab sound utilizing Fast Fourier Transform (FFT) for spectrum analysis via a PicoScope. The highest note is Bb (Bb3 = 0.231 kHz), played on the 1^st string. The intermediate note is F (F3 = 0.172 kHz) played on the 2^nd string. The lowest note is C (C3 = 0.135 kHz), played on the 3^rd string. For string 1, the fundamental pitches (f0) were 0.222 kHz, 0.237 kHz and 0.224 kHz for rebab A, B, and C, respectively. For string 2, the f0 were 0.174 kHz, 0.177 kHz and 0.168 kHz for rebab A, B and C respectively. For string 3, the f0 were 0.125 kHz, 0.149 kHz and 0.126 kHz for rebab A, B and C respectively. All the strings show non-harmonicity.

To address the issue of excessive soil content in straw feed after harvesting by a straw feed harvester, this study designed a dust removal apparatus. Its optimal operating parameters were determined through a combination of numerical simulations and field experiments. Using dust removal efficiency as the evaluation criterion, the Box-Behnken experiment and variance analysis revealed that the factors influencing the dust removal efficiency of the apparatus, in order of significance, were the number of dust removal drums, the aperture of the dust sieve, and the rotational speed of the dust removal drums. The optimal parameter combination consisted of 5 dust removal drums, a dust sieve aperture of 5 mm, and a drum rotational speed of 370 r/min. The dust removal efficiency obtained from numerical simulation using these optimal parameters was 94.1%, while the field verification test yielded an efficiency of 93.5%, with a relative error of 0.64% between the two results, confirming the accuracy of the numerical simulation parameters. The optimized dust removal apparatus significantly improves the quality of straw fodder by reducing dust content, which not only enhances the efficiency of straw recycling but also supports sustainable agricultural practices, promoting both mechanization and green development in the industry.

ZnO nanoparticles were synthesized using the raw juice of Kaffir lime (Citrus hystrix) fruit bya simple and cost-effective green route and its effects on earthworms, Eudrilus eugeniae, were studied. The kaffir-lime powered ZnO nanoparticles (ZnO:KL) were characterized by X-ray diffraction (XRD), UV-Vis-NIR spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The filter paper method was adopted to test the toxicity of ZnO:KL. Earthworms (species Eudrilus eugeniae) were exposed to 100 to 1000 mg/L of ZnO:KL in one-step order. During the study period (up to 48 h), no mortality was found in any treatment group. In histological observation, no damage was found in the epidermal layer of earthworm’s skin treated up to 800 mg/L, whereas slight epidermal damage was observed only in 900 and 1000 mg/L treated earthworms. The GC-MS spectrum of the juice of kaffir lime fruit revealed 22 bioactive compounds. The predominantly identified bioactive compounds vitamin C and citric acid were subjected to molecular docking to reveal their binding affinity with collagen – a structural protein providing strength and flexibility of the earthworm’s body. Vitamin C and citric acid bind to the collagen in a favorable orientation with the binding affinity of -4.44 kcal/mol and -4.97 kcal/mol, respectively. Since vitamin C and citric acid are capable of influencing the biosynthesis of collagen, they could prevent skin damage. In sum, the kaffir lime-powered ZnO nanomaterial is less toxic to the earthworm when compared with bare ZnO.

This study examined the volatile organic compounds (VOCs) in Stropharia rugosoannulata Farlow that were cultivated on four substrates formulated with agricultural and forestry wastes. The VOCs were analyzed by an electronic nose (E-nose), gas chromatography-ion mobility spectroscopy (GC-IMS), principal component analysis (PCA), and an orthogonal partial least squares discriminant analysis (OPLS-DA). A4(40% sawdust, 30% camellia shells, 20% rice husk, 8% bran, and 2% lime) was the most effective overall at determining the quality of flavor. The E-nose showed that there were similar profiles of aromas for A2(100% Eleusine coracana (L.) Gaertn straw) and A3(70% bamboo chips, 20% rice husk, 8% bran, and 2% lime). A total of 91 VOCs, including 82 known compounds, such as formaldehyde, alcohols, esters, and ketones, and 9 unknown compounds, were detected in each sample by GC-IMS. The relative contents of formaldehyde, ketones, alcohols, and esters in the samples was more than 80%. Among the 29 VOCs with variable importance in projection (VIP) values > 1 and P < 0.05, formaldehyde, heptagonal(dimer), 2-methyl-E-2-butenal-M”, 3-methyl-2-butenal-M(dimer), 1-octen-3-ol, butyl acetate(dimer), ethyl 3-methylbutanoate, and 2-pentylfuran were the markers that distinguished the volatiles in S. rugosoannulata cultivated with different groups of raw substrate materials.

Compared to ordinary white wheat, colored wheat has an enhanced nutritional profile, with nutrients primarily distributed in the bran layers. In this study, debranning technology was utilized to regulate debranning times and selectively debranned outer layer, middle layer, and aleurone layer of colored wheat bran to analyze the distribution of nutrients within these layers. Iron, selenium, zinc, and calcium in the bran of black wheat were more than five times higher than in the flour. Iron and calcium were concentrated in the outer layer of the bran, while selenium and zinc were mainly found in the aleurone layer. Pigment compounds and total phenolics were distributed in the middle layer of the wheat bran, with the anthocyanin content in this layer being over 20 times higher than that in the flour. The majority of dietary fiber was found in the endosperm layer. The outer layer of the bran was dominant in iron, selenium, and dietary fiber. The middle layer had higher levels of lutein, alkylresorcinols, and anthocyanins, while the aleurone layer featured a more even distribution of nutritional components. This article provides theoretical support for incorporating nutrient-rich bran layers into flour in future applications.

Deep drawing of paperboard has shown promising results for the packaging industry due to its high productivity, economical process routes, and geometrical freedom. Paper, as a material, offers a combination of compostability and recyclability while consisting of renewable resources. However, formed paper can exhibit wrinkles due to the excess material during the deep drawing process. Wrinkles form differently depending on the anisotropic behavior caused by fiber orientations. To control material deformation while forming asymmetric components the sheet metal industry uses draw beads. This paper investigates the impact of draw beads on paperboard forming. The goal is to avoid additional process steps while increasing the achievable drawing depth as well as the wrinkle control. The design of the draw beads, including their advantages and disadvantages, is discussed based on experimental tests and compared with numerical simulations. Results show that while draw beads increase drawing depth and reduce wrinkles, their position and length affect the severity and distribution of wrinkles, as well as the wrinkle-free distance.

Lipases degrade triglycerides and are used in detergent, biodiesel production, and chemical industries. In this work, lipase-producing fungal strains were enriched. A total of 10 morphologically different fungi were isolated and screened for lipase production. The isolated indigenous Aspergillus niger LP4 utilized a mixture of Calophyllum inophyllum oil cake and coconut oil cake (1:1), showing greater lipase production (127.5 ± 5.5 U/g substrate) than Calophyllum inophyllum oil cake (120.2 ± 3.4 U/g substrate) and coconut oil cake (103 ± 1.8 U/g substrate). A one-variable-at-a-time approach revealed optimum pH at 6.5 (139.2 ± 4.5 U/g substrate), 30 °C (152.4 ± 7.3 U/g substrate), 6% (v/w) inoculums (174.1 ± 5.4 U/g substrate), and 60% moisture content (180.5 ± 3.3 U/g substrate). After screening bioprocess variables by the traditional method, the selected three variables (pH, inoculum concentration, and moisture level) were optimized by the central composite design experiment. The central composite design gave 2.1-fold more lipase production compared to an unoptimized medium. The F-value of the designed model was 12.98, and the p-value was 0.0002. In this model, the terms A, B, C, A2, and C2 were significant model terms. The crude lipase showed exceptional compatibility with detergents, improved wash performance, and released free fatty acids from the wastewater.