Research Articles

This study considered the ‘Gendang Kecapi’ (GK) musical instrument, the sounds of which were recorded in an anechoic chamber. The Fast Fourier Transform (FFT) data was obtained using a Picoscope oscilloscope. The GK is an idiochord bamboo tube zither from Kelantan, Malaysia. The GK have two strings (called canang), two gongs, and a gendang (drum). The instrument produced unique and innovative sounds. The time frequency analysis (TFA) used Adobe Audition to produce the spectrograms. The fundamental frequency (f0) of string 1 (canang ibu) and string 2 (canang anak) are 0.888 kHz (A5) and 1.054 kHz (C6), respectively. The f0 of gong 1 (gong ibu) and gong 2 (gong anak) are 0.230 kHz (A3#) and 0.246 kHz (B3), respectively. The f0 of gendang is 0.380 kHz (F4#). The frequency spectrum showed less distinct fundamental frequency with several lower partial frequencies at 0.017, 0.100, and 0.200 kHz.

The economic and agronomic impacts of drip fertigation techniques were evaluated on tuberose (Polianthes tuberosa L.) cultivation in a semi-arid region. Conducted over two growing seasons (2022-2024) at the ICAR-Indian Agricultural Research Institute in New Delhi, the field experiments utilized a split-split plot design with three factors: land configuration (raised bed and flatbed), irrigation schedules (50%, 75%, and 100% pan evaporation), and fertigation schedules (50%, 75%, and 100% recommended dose of fertilizers). Data were collected on flower yield, water productivity, and economic returns. The raised bed system consistently outperformed the flat bed system in water productivity and flower yield. Among the irrigation levels, the highest water productivity and flower yield were observed at 100% pan evaporation. Similarly, the highest fertigation level (100% RDF) resulted in the best outcomes in terms of both yield and economic returns. The economic analysis revealed that the raised bed configuration with higher fertigation and irrigation levels (BI3F3) was the most profitable, with the highest benefit-cost ratios. The study concludes that optimizing fertigation and irrigation practices, particularly using raised bed configurations with higher fertigation and irrigation levels, can significantly enhance tuberose cultivation’s profitability and sustainability in water-scarce regions.

To explore the feasibility of replacing inorganic fibers with plant fibers for the fabrication of polymer composites for waterfront engineering applications, the effects of replacing glass fibers with bamboo fibers on the mechanical and erosive wear properties of high-density polyethylene (HDPE) composites were investigated. Mechanical performance tests and the hydraulic abrasive erosive wear technique, which is based on a rotating jet system, were employed. The results indicated that as the mass ratio of bamboo fibers to glass fibers increases, the mechanical properties of the HDPE composites improved overall, while the erosion resistance initially decreased and then increased. The maximum increases in tensile, flexural, and impact strength, as well as breakage elongation were 16.4%, 13.8%, 34.9%, and 10.0%, respectively. Bamboo fibers, when replacing glass fibers, can form chemical bonds with the matrix, suppressing the brittle fracture characteristics observed in the tensile sections of HDPE composites. However, this substitution also reduced the erosion resistance of the HDPE composites. The wear characteristics of the eroded surfaces mainly include a brittle fracture of the matrix and fragmentation, as well as extensive exposure of the bamboo fibers.

Significant quantities of bark are generated during wood processing, with the majority being utilized for energy production and soil enhancement. This study investigated the influence of bark particle size and resin type (urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF)) on the properties of particleboards made from spruce and pine bark. Board samples were fabricated using different bark particle sizes (2 to 5 mm and 5 to 8 mm) and varying adhesive contents (5% and 7%) for both UF and MUF adhesives. Reference particleboards were manufactured using industrial wood particles with the same UF and MUF adhesive contents. The spruce bark consistently outperformed pine bark across most investigated properties. Board samples fabricated from spruce bark particles exhibited higher internal bond (IB) strength and modulus of rupture (MOR), as well as enhanced resistance to water absorption (WA) and thickness swelling (TS), particularly when bonded with urea-formaldehyde (UF) adhesive. Specifically, boards composed of spruce bark, using a combination of bark particle sizes, UF adhesive, and 7% adhesive content, exhibited superior performance in IB strength, water resistance, and modulus of elasticity.

Reed was used as a raw material to develop a low-temperature oxygen-alkali pulping process, and a mathematical prediction model was established to evaluate the impact of process variables on pulping performance. Additionally, the dissolution behavior of reed’s chemical components was analyzed to elucidate the synergistic mechanism of oxygen-alkali pulping. The results revealed that optimal pulp performance was achieved at a maximum temperature of 114.5 °C, a retention time of 3.88 hours, and a sodium carbonate-to-sodium hydroxide molar ratio of 1/10. Under these conditions, the pulp yield reached 50.5%, with a brightness of 55.5% ISO, a viscosity of 465 mL/g, and a kappa number of 16.2. Notably, most of the silicon remains in the pulp, with only 34.1% migrating to the black liquor, thereby mitigating silica-related interference during alkali recovery. Variance analysis of the response surface confirmed that the investigated variables had significant impacts on all response indices, and the developed predictive model demonstrated high accuracy in forecasting the pulping performance of reed. Furthermore, the physical properties of the paper produced under these optimal conditions were superior to those of the paper obtained by using conventional high-temperature oxygen-alkali pulping processes.

The thermal properties of starch/PVOH formulations gelatinized with glycerol, cross-linked with boric acid, incorporated with clay and loaded with 2 wt%, 4 wt%, and 7 wt% sayote fibers were investigated. The FTIR spectra, SEM micrographs, DSC, and TGA results revealed a successful blending in starch/PVOH (50/50) and starch/PVOH (65/35) fomulations with glycerol as plasticizer and boric acid as cross-linking agent. Plasticized and cross-linked starch/PVOH reinforced with clay and varying amounts of sayote fiber suggest more inter- and intra- molecular hydrogen bonding interactions, making the composite more crystalline and thermally stable. The SEM micrographs showed a smoother surface with the addition of boric acid and a more orderly woven surface with 2 wt% sayote fiber loading. DSC thermograms reveal that the formulations were compatible and had good blending interactions, since the experimental enthalpies of melting were higher than their theoretical values. The addition of sayote fiber increased the thermal stability of starch/PVOH composite blends and prevented the re-crystallization of starch. TGA curves showed that the addition of sayote fibers formed stronger blends that delayed the degradation of the composite. The starch/PVOH (50/50) and starch/PVOH (65/35) composite blends were more crystalline and thermally stable at 2 wt% to 4 wt% sayote fiber loading.

The objective of this study was to determine both the physical and mechanical properties of experimental panels made from recycled corrugated cardboard. Two types of composite samples, derived from two different raw materials — namely, unprinted and printed cardboard — were manufactured. The physical characteristics of the specimens, including density, water absorption, dimensional stability, thermal conductivity, and sound absorption, were tested. Additionally, the mechanical properties, such as the modulus of elasticity, modulus of rupture, and internal bond strength, were evaluated. Based on the findings of this research, the samples made from unprinted cardboard exhibited higher density, lower thickness swelling, and slightly better thermal insulation properties than those made from printed raw material. In contrast, the samples containing printed material demonstrated superior mechanical properties, suggesting they may be more suitable to be used where structural properties are desired. Overall, the properties of both types of samples indicate that such panels have an important potential to be used as sustainable products, serving as a green alternative material for indoor applications.

Impact-resistant automotive components were studied by evaluating the effects of single-screw and twin-screw extrusion on the mechanical properties of composites made from fluorene-modified nanocellulose (FCF) or bamboo fibers (30 wt%) combined with various polymers. Natural fiber composites were injection molded, and their mechanical properties were evaluated. Results showed that fluorene-modified nanocellulose exhibited improved dispersion when kneaded with polycarbonate and polyamide 6 using twin-screw extrusion, resulting in increases of over 5000 MPa in flexural modulus and over 40 MPa in maximum flexural stress compared to the base polymer. However, composites made with polyamide 66 and bamboo fibers required high injection molding temperatures exceeding 260 °C, which led to thermal degradation and reduced the fiber reinforcement effect on mechanical properties. The polypropylene showed weak interfacial compatibility with bamboo fibers, resulting in limited reinforcement effects in both single and twin-screw extrusion. The brittleness of the fibers did not significantly influence the elongation of the PP composite. Nonetheless, it exhibited less reduction in elongation compared to composites where bamboo or FCF was added to other polymers. Building on these results, flexural tests were conducted on composites combining high-impact polypropylene with natural fibers, demonstrating the potential for high-impact-resistant composite materials suitable for automotive applications.

Biochars, produced via pyrolysis, are gaining attention in applications ranging from soil amendments to energy storage and environmental remediation. While lignocellulosic biochars from woody biomass are well studied, algal biochars remain comparatively overlooked despite offering diverse organic and inorganic content that may broaden their applications. This study investigates how pyrolysis temperature and oxidative pretreatment affect the structure and properties of biochars derived from two macroalgae, Ulva expansa and Sargassum sp., under various pyrolysis conditions (500 to 900 °C). Using Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, and nanoindentation, it was found that the C-O and C-N surface functional groups decreased in Ulva but the C=O and C-O-C groups increased in Sargassum upon pyrolysis. The reduced modulus ranged between 2.6 to 7.9 GPa and was governed by pyrolytic carbon content and inorganic composition. Of these two factors, the amount and type of pyrolytic carbon were determined by the heating conditions, with oxidation at 200 °C generally preserving more carbon than oxidation at 300 °C. Meanwhile, the final pyrolysis temperature dictated residual carbon content, salt formation, and carbonation. These findings highlight the potential for tailored pyrolysis to produce algal biochars with customizable structures and properties, enabling environmental and industrial applications such as carbon sequestration, filtration, and energy storage.

In response to the green development concept of the textile industry, this article describes the development of a biodegradable and eco-friendly raw starch sizing agent formulation. The sizing agent performance, sizing quality, biodegradation, weave efficiency, and production cost of the raw starch formulation in raw starch sizing process were compared with three other formulations. The results showed that the formulation prepared with raw starch achieved a lower viscosity and higher stability compared with the other three formulations. The raw starch sizing exhibited excellent moisture regain, moisture absorption performance and breaking strength, high enhancement rate and low elongation, high penetration, low coating, and abrasion resistance. The raw starch formulation was shown to be energy-saving and environmentally friendly, with higher weave efficiency and lower production costs. The BOD₅/COD was 0.65, which means that the desizing wastewater is easy to degrade. Sizing agent cost was 17 to 61% lower and loom efficiency was 5% to 12% higher. This research provides a theoretical basis for promoting the usage of raw starch sizing in practical production, which contributes to green and eco-friendly processing.