Research Articles

Traditional menstrual absorbent pads typically combine cellulose fiber fluff pulp with non-biodegradable, petroleum-based superabsorbent polymers (SAPs). To eliminate the need for SAPs, this study explores foaming as a method to create a highly porous lignocellulosic fiber network capable of storing large amounts of fluid. Bamboo fibers were chosen due to their high lignin content, which is expected to help maintain the structural integrity of the porous network during liquid absorption and preventing collapse compared to 100% cellulose fibers. The bamboo fiber foams demonstrated remarkable porosity and superior absorbency compared to commercial pads, but they exhibited lower water retention when subjected to compression. Refining the fibers and incorporating microfibrillated cellulose offer promising opportunities to enhance water retention.

Biochar derived from biomass resources as a carrier to load SnO₂ for electroreduction of CO₂ not only can benefit carbon emissions, but it also can achieve waste utilization. However, the weak CO₂ mass transfer and conductivity ability of SnO₂/biochar limits its applications to such eCO₂RR processes. This study focused on modifying SnO₂/biochar with amino groups and investigated the effects of positioning of amino groups on the catalyst’s physicochemical properties and electrocatalytic behaviors. Elemental analysis revealed that anchoring amino groups on biochar (SnO₂/C-NHx) is advantageous for increasing amounts of amino groups attached, thereby enhancing biochar adsorption energy and subsequently increasing the loading of Sn. The CO₂ adsorption curve indicated that amino groups anchored on biochar facilitate CO₂ adsorption due to high specific surface area of biochar. X-ray photoelectron spectroscopy showed that amino groups anchored on SnO₂ (NHx-SnO₂/C) resulted in highly electron-rich centers on Sn, which promoted electron transfer between the catalyst and CO₂. Electrochemical tests demonstrated the improved performance of amino-modified SnO₂/biochar. SnO₂/C-NHx exhibited enhanced Faraday efficiency, whereas NHx-SnO₂/C showed higher current density. The disparity in electrochemical performance can be mainly attributed to the different selectivity towards rate-controlling steps of electron transfer and mass transfer induced by the various positions of amino groups anchoring.

Timber connections were prepared using glulam from tropical plantation species, focusing on key properties for dowel-type joints with half threaded bolts without nuts: Bolt bearing strength and bolt withdrawal capacity. Tests were performed according to ASTM standards. Three half-threaded bolt diameters (12 mm, 16 mm, and 20 mm) were tested in two loading directions, parallel and perpendicular to the grain, with 12 replicates for each configuration. Response Surface Methodology (RSM) using Design Expert Software was applied to optimize bolt diameter for both loading directions. Results showed that bolt bearing strength was higher in perpendicular loading, with the 12 mm bolt achieving 16.6 N/mm², compared to 6.01 N/mm² in parallel loading. Withdrawal capacities varied, with the 16 mm bolt showing the highest capacity in perpendicular loading at 54.2 kN. The study demonstrates that the 16 mm bolt exhibited the optimal diameter-to-embedment length ratio compared to 12 mm and 20 mm bolts, resulting in the highest withdrawal capacity. Consequently, the 16 mm bolt represented the best balance for achieving maximum withdrawal capacity. The optimization suggests using a 16 mm bolt for parallel loading to the grain and a 14 mm bolt for perpendicular loading.

The hardness of the wood surface determines its wear resistance and resistance to mechanical damage. This study aimed to determine the effect of walnut tannin used in wood preservation on the surface properties of wood. For this purpose, Scots pine (Pinus sylvestris L.) and walnut (Juglans regia L.) wood test specimens were treated with walnut tannin with a brush. The specimens then were coated with  water-based and polyurethane varnishes. After drying, the surface hardness was measured. As a result of the research, it was determined that the highest surface hardness was in the control samples without tannin application and the highest value was in walnut wood.

The commercial value of teak wood is associated with its heartwood, which has a naturally darker color than sapwood. To reduce this color disparity, thermal modification can be used to homogenize the color between sapwood and heartwood by minimizing color differences. This research aimed to assess the effectiveness of thermal modification in making the color of teak sapwood similar to that of heartwood. Thermal modification was carried out at 160, 180, 200, and 220 °C for 150 min. Thermal modification of teak sapwood at 180 °C ensured greater color similarity to the heartwood of a fast-growing 16-year-old plantation. The material darkened with increasing process temperature. There was a change in the content of soluble substances, and hot water extraction had greater correlations with hue angle, lightness, and yellowness. Thermal modification also reduced the number of hydroxyl groups and improved the wood’s thermal stability.

The bundengan is a unique traditional musical instrument with plucked strings from Wonosobo, Central Java, Indonesia. It can produce sounds that imitate the gong (i.e., a part of the gamelan instrument). The bundengan was initially constructed by duck herders as a means of shielding themselves from inclement weather while caring for their flocks. They also engage in musical activities and singing. The distinctive sound of the bundengan is created by plucking a set of strings fitted with tiny bamboo clips using the right hand and three elongated, slender bamboo blades with the left hand. The sound effect is produced by the bandulan, a small piece of bamboo attached to the string. The tuning of the bundengan depends on the player’s instinct. This study analyzed the pitch and timbre of the bundengan strings. Using Fast Fourier Transform (FFT), the sound from a plucked string yields the frequency spectrum of the actual vibrations from the strings. The results were used to validate the frequency as heard. The results showed that the pitch from the measured frequencies is not similar to the pitch as heard. The bundengan is tuned to a pitch corresponding to the timbre rather than a specific pitch.

Self adhesion is a simple and effective bonding technique that can be used to produce environmentally friendly and green straw-based fiberboard (CLS) through deep eutectic-like solvent (DES) treatment. This article mainly introduces the use of DES composed of choline chloride and oxalic acid. DES is diluted with deionized water and straw is immersed in it, and finally dried into pretreated fiber raw materials. Fiber boards are prepared by adjusting the hot pressing parameters and the preset moisture content of straw itself for hot pressing solidification. The aim of this study was to investigate the effects of different processing parameters (hot pressing temperature and straw moisture content) on the microstructure, physical properties, and mechanical properties of CLS. Straw-based fiberboard heated at 180 ° C exhibited the best mechanical and water resistance performance. The fiberboard reached its highest mechanical performance at a moisture content of 50%. The bending performance of fiberboard produced at 180 °C reached 13.5 MPa, and compared with the board manufactured at 120 °C, the bending strength, tensile strength, and internal bonding strength increased by 320%, 224%, and 280%, respectively.

Drought is an environmental stress that can negatively influence growth and productivity of fruit trees because it decreases the photosynthetic rate and stomatal conductance and raises the rate of water loss from the plant surfaces. Therefore, this study investigated the soil application of biochar individually or in combination with the spraying of boron, silicon, and molybdenum relative to the growth attributes, fruit drop percentages, yield, and fruit quality of Le Conte pear trees grown under drought stress. The trees were fertilized by biochar at 0, 1, and 2 kg per tree individually or in combination with the foliar spraying with 0 mg B₂O₃ + 0 mg SiO₂ + 0 mg MoO₂, 10 mg B₂O₃ + 25 mg SiO₂ + 25 mg MoO₂, 20 mg B₂O₃ + 50 mg SiO₂ + 50 mg MoO₂ and 30 mg B₂O₃ + 75 mg SiO₂ + 75 mg MoO₂ at start of February, start of March and start of April, compared to untreated trees (control). The results showed that the soil addition of biochar or spraying of nano fertilizers individually or in combinations improved the vegetative growth, productivity and fruit quality, and leaf mineral content, meanwhile they reduced the fruit drop. The best results were obtained by the application of 2 kg biochar combined with 30 mg B₂O₃ + 75 mg SiO₂ + 75 mg MoO₂, which was superior to other applied treatments in the two seasons.

It is acknowledged that boron, ammonium, and nitrogenous compounds, which are used today as fire retardants, cause an increase in the hygroscopicity of wood materials. In this study, Scots pine (Pinus sylvestris L.), Anatolian chestnut (Castanea sativa Mill.), and Eastern spruce (Picea orientalis Link) woods were impregnated with 1.5% nano-sized hexagonal boron nitride (NB) according to ASTM D1413-76 (1976) standards. Flame-induced combustion (FIC), self-combustion (SC), and glowing combustion (GC) temperatures were determined. The highest retention amount was measured in spruce and the lowest was in chestnut among the wood samples taken for testing and measurement. When compared with the control samples, NB application caused an increase in SC and FIC temperatures (at higher rates). According to the glowing combustion temperature control samples, an increase was observed in chestnut and spruce and a decrease was observed in Scots pine among the samples applied with NB.

Partial delignification of alder wood specimens was performed with alkaline sulfite and peracetic acid (PAA) methods, and subsequently the delignified samples were saturated with furfuryl alcohol, as an eco-friendly chemical. The aim of delignification before furfurylation was to facilitate the penetration of furfuryl alcohol into the cell wall, in order to overcome the weak mechanical properties and hydrophilicity of alder wood as a fast growing species. The results showed that alkaline delignification removed a lower percentage of lignin despite more significant mass loss as compared to peracetic acid delignification method, which indicates more carbohydrates degradation in alkaline delignification. Infrared spectroscopy also confirmed more retention of carbohydrates in the sample delignified with peracetic acid. The polymerization of furfuryl alcohol in the cell cavities decreased the access of water molecules to the hydroxyl groups of the cell wall, increased the contact angle, and decreasing surface wettability. This effect was more noticeable in the PAA-delignified samples. Mechanical tests revealed that the delignified samples with peracetic acid had higher mechanical strength and modulus, compared to the alkaline sulfite delignified samples. This was attributable to the maintenance of carbohydrates during the delignification process.