Volume 19 Issue 4

Cellulose is a widely available organic substance that forms membranes with excellent hydrophilicity and biocompatibility. However, it is prone to biological contamination because its surface is conducive towards the accumulation of biologically active substances, which has hindered its application potential. In this work, an antimicrobial cellulose-based membrane (Ag/UiO-66-NH₂@BCM) with high water flux, high retention rate, and good hydrophilicity was prepared. At an optimal blend ratio of 1 wt% Ag/UiO-66-NH₂, the membrane exhibited significant improvements, including a 31% increase in pure water flux, a Bovine Serum Albumin retention rate of 99.6%, and a water flux recovery of 97.4%. Crucially, the membrane demonstrated potent antibacterial, showcasing its broad-spectrum antimicrobial properties. Investigations into the ability of Ag/UiO-66-NH₂@BCM to remove Pb²⁺, Cd²⁺, and Cr⁶⁺ ions from a water column revealed that the maximum adsorption capacity of the monolayer was 405, 390, and 328 mg/g, respectively. The composite membrane demonstrated broad-spectrum and highly effective antimicrobial properties, along with efficient removal of heavy metal ions. The proposed method can be utilized to prepare other composite membranes for water treatment and other fields of membrane separation technology.

Bast fiber from paper-mulberry (Broussonetia papyrifera) has long been utilized for handmade paper in Asia, serving as a prominent non-wood cellulose material. When restoring paper cultural assets, selecting a similar paper to the original ensures longevity and prevents deterioration issues like warping or tearing. The production of handmade paper involves several processes, including refining, steaming, and bleaching of raw materials. Once formed into sheets, the physical properties of the paper are dictated by these materials and remain unchanged unless the paper is newly made. Handmade paper production is labor-intensive and time-consuming, emphasizing the need for careful raw material selection to match desired characteristics. This study evaluated the dendrological, morphological, anatomical, and chemical compositions of three paper-mulberry wood types cultivated in Korea and inferred their suitability as pulp for papermaking or repair of archival paper specimens. Paper-mulberry wood showed differences in fiber length according to molecular phylogenetic characteristics, but there were no differences in anatomical characteristics owing to the immaturity of the wood. This study investigated the characteristics of the bast fibers from the bark of paper-mulberry trees with different genetic traits to identify favorable factors likely to affect the pulp and papermaking process and paper quality.

Food waste is an excellent source of various bioactive secondary metabolites. In addition, food waste is a global issue, and more research is being focused on the conversion of value-adding products from food waste, especially fruits. In this study, bioactive polyphenols were extracted from orange peels. The parameters that affect the extraction of polyphenols from orange peels were optimized using response surface methodology. Ethanol was used to extract bioactive polyphenols, and the extraction time (min), extraction temperature, and ethanol concentration (%) were analyzed. Orange peels are an excellent source of polyphenols, and the yield was increased under optimized extraction conditions (p<0.05). The polyphenol content increased twofold (38.4 mg GAE/g) under the optimized extraction conditions (53% ethanol, 51 degrees centigrade and 96 min extraction time). Crude polyphenols exhibited significant antibacterial activity against Bacillus subtilis (19±1 mm zone of inhibition), followed by Staphylococcus aureus (17±2 mm zone of inhibition) (p<0.05). In addition, orange peel extract exhibited antifungal activity against A. flavus and C. albicans. The ethanol extract exhibited DPPH activity (1.61±0.03 mg GAE/100 g) and ABTS reducing power (1.48±0.01 mg GAE/100 g). The polyphenol compounds exhibited antibiofilm activity against biofilm-producing Bacillus subtilis and increased in a dose-dependent manner (p<0.05).

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.