Nowadays, arsenic (III) contamination of drinking water is a global issue. Laboratory and instrument-based techniques are typically used to detect arsenic in water, with an accuracy of 1 ppb. ...However, such detection methods require a laboratory-based environment, skilled labor, and additional costs for setup. As a result, several metal-based nanoparticles have been studied to prepare a cost-effective and straightforward detector for arsenic (III) ions. Among the developed strategies, colorimetric detection is one of the simplest methods to detect arsenic (III) in water. Several portable digital detection technologies make nanoparticle-based colorimetric detectors useful for on-site arsenic detection. The present review showcases several metal-based nanoparticles that can detect arsenic (III) colorimetrically at a concentration of ~0.12 ppb or lower in water. A literature survey suggests that biomolecule-based metal nanoparticles could serve as low-cost, facile, susceptible, and eco-friendly alternatives for detecting arsenic (III). This review also describes future directions, perspectives and challenges in developing this alternative technology, which will help us reach a new milestone in designing an effective arsenic detector for commercial use.
Various natural sound-absorbing materials such as rice by-products, coir fiber, date palm fiber, peanut husks, hardwood cross-sections, and forest by-products have been introduced to replace ...petroleum-based sound-absorbing materials in previous studies, and their sound-absorbing performance was significant. This study investigated the sound-absorbing performance of pure coffee grounds as an eco-friendly sound-absorbing material. After inserting coffee grounds into cylindrical holders with lengths of 20, 30, and 40 mm, the density of the coffee grounds was adjusted from 0.2 to 0.5 g/cm3. Then, the sound absorption coefficients were measured by an impedance tube. As the thickness and density increased, the sound absorption coefficient at low frequencies improved. However, the sound absorption coefficient at high frequencies decreased. The optimal noise reduction coefficient (NRC) of coffee grounds investigated in this study was 0.61 at a density of 0.3 g/cm3 and thickness of 50 mm. This result shows a sound-absorbing performance that is comparable to other natural sound-absorbing materials. This study concludes that coffee grounds have high use-value as an eco-friendly sound-absorbing material.
Loud noise has become a regular part of life due to growing urbanization and lifestyle changes, making noise pollution a severe health concern. However, eco-friendly materials for low-frequency sound ...absorption still need improvement. Wooden puzzle-assembled boards are being used to construct wooden buildings in South Korea, but they require better sound absorption performance. Therefore, we have developed a strategy to enhance the sound absorption capability of wooden puzzle-assembled boards by suggesting the installation of a single-frequency resonator on the board. The resonator contains nine pinholes with a 6 mm diameter perforation connected to a 30 mm diameter hole leading to the center hollowed cavity (CHC). We evaluated the sound absorption coefficient (SAC) of the control (i.e., cross-laminated timber (CLT)) and a resonator board. The SAC of the resonator with zero pinholes (i.e., CHC), one pinhole (PH-1), five pinholes (PH-5), and nine pinholes (PH-9) were estimated using a two-microphone transfer function method at low frequencies ranging from 100 to 1600 Hz. The average SAC of PH-9 showed significant improvement at the frequency of 450 Hz (0.637 ± 0.001; 818%) compared to the control samples. The noise reduction coefficient was improved by 239% (0.07 for the control and 0.23 for the PH-9). We compared the experimental results in this study with theoretical results and found that the orientation of the neck length significantly impacted the resonant frequency of the pinhole resonator. This finding provides valuable insights into the design and optimization of pinhole resonators for specific acoustic applications.
•A wooden puzzle board that can be used to construct wooden structures.•New low-frequency sound absorption strategy.•A nine-pinhole (6 mm) resonator exhibits excellent sound absorption at 450 Hz.•Impressive results could entice both the manufacturer and the customer.
The rational design of sound absorption boards made of wood materials is an exciting area of research. This article describes a simple and inexpensive method to increase the sound absorptions ...capacity of Malas hardwood (Homalium foetidum Roxb.) using ammonium persulfate treatment. The reaction parameters such as the concentration of ammonium persulfate and reaction time were optimized. The results of X-ray photoelectron spectroscopy, X-ray diffraction, attenuated total reflectance–Fourier transforms infrared spectroscopy, and scanning electron microscopy demonstrated that ammonium persulfate could significantly affect carbohydrate polymers and lignin of wood by improving oxygen functionalities. The quantitative analysis of carbohydrate polymers (hemicellulose and cellulose) and lignin were evaluated. These changes in carbohydrate polymers and lignin enhanced the air permeability (83.6%) and average sound absorption coefficient at each frequency range 500–1000 Hz (2.6%), 1000–2000 Hz (4.9%), 2000–4000 Hz (17.4%), and overall 500˗6400 Hz (20.8%) compared to the control samples. These results could be beneficial for new research and wood-based sound absorption materials to regulate the acoustic environment in houses.
•Ammonium persulfate changes carbohydrate polymers and lignin.•The modified biopolymers enhanced the porosity (1.2%) and gas permeability (83.6%).•The average sound absorption coefficient increases 20.8% at 5–6.4 kHz.•The ammonium persulfate method is facile and inexpensive.
The rational design of sound absorption boards made of wood materials is an attractive field of research. This article describes a simple and low‐cost ammonium persulfate treatment on coconut wood ...cell walls (Cocos nucifera L.). Reaction parameters such as concentration of reactant and reaction time were optimized. The results of different instrumental characterization such as X‐ray photoelectron spectroscopy, X‐ray diffraction, attenuated total reflectance–Fourier transforms infrared spectroscopy, and scanning electron microscope supports the chemical alterations of the wood cell wall. The quantitative analysis of hemicellulose, cellulose, and lignin was performed. The significant changes in cell‐walls enhanced average sound absorption coefficient at each frequency range: 60.4% at 500–1000 Hz (t = −10.593 and p < 0.001), 80.8% at 1000–2000 Hz (t = −4.798 and p < 0.001), 96.2% at 2000–4000 Hz (t = −58.527 and p < 0.001) and 83.0% at 500–64000 Hz (t = −51.261 and p < 0.001). It is due to the increment of gas permeability (288.3%, p = <0.001). These results could be beneficial for new research on wood‐based sound absorption materials to regulate the acoustic environment in houses.
Multi-family homes have been constructed traditionally using heavy materials like concrete/steel and bricks. Wooden structures are a promising substitute for typical heavyweight constructions. ...However, floor impact noise has been identified as the most annoying noise source in South Korea. Here, we have studied the effect of floorboard installation on impact sound changes before and after installing the floorboard on the floor of a wooden building. We used standard tapping and bang machines in this study to generate lightweight and heavyweight impact sounds. The changes in noise from lightweight and heavyweight impact sounds were estimated on the upper layer (UL) and lower layer (LL) floors before and after the installation of the plywood floorboard (PFB). The average of the octave band center frequencies at 125, 250, 500, 1000, and 2000 Hz from the lightweight impact before installation of PFB was 84.08 dB (UL) and 50.54 dB (LL), respectively, while 84.04 dB (UL) and 41.90 dB (LL) after the installation of the surface decorated PFB. Similarly, the heavyweight impact sound before installing PFB was 73.26 dB (UL) and 42.16 dB (LL), respectively, while after installation of PFB, impact sound appeared at 71.58 dB (UL) and 42.48 dB (LL). The results exhibited that lightweight impact sound could be reduced by about 8.6 dB on the LL. These results could entice the researcher or building engineer to design wooden floorboards for a comfortable building environment. This study is new because it compares the impact sound of the floor before and after it has been constructed.
•Lightweight and heavyweight impact sounds were studied in a wooden house.•An ondol heating system was installed in the middle layer of the floor.•The lightweight impact sound was effectively reduced (8.6 dB) by a 10 mm floorboard.•Significantly reduces the high-frequency impact sound of heavyweight impact sound.•This approach could improve the acoustical building environment.
The subject of the present paper is improving sound absorption properties and protecting the dust generation of ceramic fiber boards. The two‐microphone impedance tube method measured the sound ...absorption coefficient (SAC) of ceramic fiberboards (CFB) with different shapes and sizes. The wood veneer was used to cover the ceramic fiberboard (VCFB) surface to improve the wall's appearance and prevent dust generation. The step‐shaped ceramic fiberboards with veneer attached (VCFBS) revealed improved SAC (.98, 2000 Hz) compared with CFB and VCFB. The noise reduction coefficient (NRC) and sound absorption average showed a 100% improvement compared to CFB. The surface morphology and air permeability were analyzed using a scanning electron microscope and a capillary flow porometer to correlate with the findings. Furthermore, the porosity and pore diameter of the CFB were also studied to gain a comprehensive understanding of its acoustic properties and sound absorption capabilities. Statistical T‐tests revealed significant variations in the SAC (p ≤ .005). Besides, the obtained SAC was compared with other reported sound‐absorbing materials. These findings suggest that using step‐shaped ceramic fiberboard covered with a wood veneer can significantly absorb sound and improve the living environment. This novel approach offers potential advancements in sound‐absorbing materials for building construction.
This study investigated the effects of surface perforation on the drying characteristics and sound absorption coefficients of Russian Simon poplar lumber. The drying process and moisture content (MC) ...were monitored. The results showed that the perforated wood samples reached 10.9% MC after 14 days, while the control samples reached 11.7% MC after 16 days. The difference in MC between the core and shell of the perforated and control specimens was 1.29% and 2.71%, respectively. The drying stress of perforated wood lumber was tension stress, while compressive stress was observed in control samples. The sound absorption coefficient (SAC) was measured using the transfer function method and two microphone impedance tubes. The results showed that the perforated samples had improved in SAC compared to the control samples, particularly at 1000 Hz. The average SAC of the perforated samples at 1000 Hz was 41% higher than that of the control samples. Furthermore, the noise reduction coefficient (NRC) exhibited a 69% improvement in the perforated samples. Statistical t-test analyses confirmed the significant difference in the SAC of the perforated pieces. Further experiments revealed that the sound absorption performance of perforated samples could be significantly improved by adding air gaps in the back cavity (1, 2, 3 cm), particularly at low frequencies. These findings suggest that perforated poplar boards could be useful for wall building applications when combined with air gaps in the back cavity to enhance sound absorption performance.
This pilot study proposed the measurement of strokes while writing English alphabets on a tablet PC with a stylus pen, followed by a set of features to evaluate writing dexterity quantitatively, with ...the aim of developing a writing skill acquisition support system for people with dysgraphia. A total of nine features were created: time traveled, mean and standard deviation of velocity and acceleration, respectively, power, misalignment, and shape deviation of speed and acceleration. We compared these features between the dominant and non-dominant hands of healthy university students. The results indicate that for those who had experienced a correction of the dominant hand, each tendency in each feature was evident, particularly in spatial features. These results suggest that our proposed method could validate writing dexterity and is expected to be applicable to dysgraphia.
PDF
