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.
Noise pollution is often overlooked and invisible, but it significantly impacts the quality of human life. One of the most straightforward solutions to mitigate noise pollution is by using ...sound-absorbing materials. Recently, research trends to develop sound absorbing green materials, typically derived from agricultural by-products, have witnessed an uptick. This paper summarizes the sound-absorbing properties of various green materials found in the literature, including coconut fiber, kenaf fiber, rice bran, rice husk, rice straw, Hanji (a traditional Korean paper), tea-leaf fiber, mandarin peel, pineapple-leaf fiber, corn husk, peanut shell, sugar palm trunk, Yucca gloriosa fiber, fruit stones, wood barks, flax fiber, and nettle fiber. Natural fibers can be made by compressing the raw material or manufacturing them into fibrous materials or composites. The key variables that determine sound absorption performance are the thickness and density of the green material, as well as the presence of an air back cavity. Generally, thicker materials exhibit better sound absorption performance in the low- and mid-frequency range. Moreover, higher density is associated with better sound absorption performance at the same thickness. Additionally, increasing the distance between the sound-absorbing material and the air back cavity enhances sound absorption performance at low frequencies. Thus, these physical variables, rather than the specific materials used, primarily influence sound absorption capabilities. Therefore, various green materials, such as fibers, granules, and porous materials, can be effective sound absorbers if their thickness, density, and air back cavity are properly controlled.
Despite the clinical and genetic significance of macrotrabecular-massive hepatocellular carcinoma (MTM-HCC), its characteristics on imaging have not been described. This study aimed to characterise ...MTM-HCC on gadoxetic acid-enhanced MRI and to evaluate the diagnostic accuracy and prognostic value of these imaging characteristics.
We enrolled 3 independent cohorts from 2 tertiary care centres. The 3 cohorts consisted of a total of 476 patients who underwent gadoxetic acid-enhanced MRI and surgical resection for treatment-naïve single HCCs. Independent review of histopathology and MRI by 2 reviewers was performed for each cohort, and inter-reader agreement was evaluated. Based on the result of MRI review in the training cohort (cohort 1), we developed 2 diagnostic criteria for MTM-HCC and evaluated their prognostic significance. The diagnostic performance and prognostic significance were validated in 2 validation cohorts (cohorts 2 and 3).
We developed 2 diagnostic MRI criteria (MRIC) for MTM-HCC: MRIC-1, ≥20% arterial phase hypovascular component; MRIC-2, ≥50% hypovascular component and 2 or more ancillary findings (intratumoural artery, arterial phase peritumoural enhancement, and non-smooth tumour margin). MRIC-1 showed high sensitivity and negative predictive value (88% and 95% in the training cohort, and 88% and 97% in the pooled validation cohorts, respectively), whereas MRIC-2 demonstrated moderate sensitivity and high specificity (47% and 94% in the training cohort, and 46% and 96% in the pooled validation cohorts, respectively). MRIC-2 was an independent poor prognostic factor for overall survival in both training and pooled validation cohorts.
Using gadoxetic acid-enhanced MRI findings, including an arterial phase hypovascular component, we could stratify the probability of MTM-HCC and non-invasively obtain prognostic information.
Macrotrabecular-massive hepatocellular carcinoma (MTM-HCC) is a histopathologic subtype of HCC characterised by aggressive biological behaviour and poor prognosis. We developed imaging criteria based on liver MRI that could be used for the non-invasive diagnosis of MTM-HCC. HCCs showing imaging findings of MTM-HCC were associated with poor outcomes after hepatic resection.
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•Macrotrabecular-massive hepatocellular carcinoma (MTM-HCC) is an aggressive subtype of HCC.•We revealed gadoxetic acid-enhanced MRI findings related to MTM-HCC.•Using MRI findings, we could non-invasively stratify the probability of MTM-HCC.•HCC without an arterial phase hypovascular component is highly unlikely to be MTM-HCC.•MRI findings of MTM-HCC could be a useful prognostic factor after surgical resection.
In this study, changes in gas permeability and pore structure of wood are evaluated after heat treatment with temperatures ranging from 190 to 230 °C for 6 h for both hardwood (yellow poplar:
...Liriodendron tulipifera
) and softwood (Korean red pine:
Pinus densiflora
). The purpose of this study is to investigate changes in pore size, content of three pore types (through pore, blind pore, and closed pore), as defined by IUPAC, and gas permeability by increasing heat treatment temperatures in hardwood and softwood using capillary flow porometry and gas pycnometry. As the heat treatment temperature increased, only through pore porosity increased, causing an increase in gas permeability.
The purpose of this study is to analyze the pore structure for the heartwood, intermediate wood, and sapwood sections in three species of softwood (hinoki, Douglas fir, and hemlock) and to ...investigate the correlation of gas permeability depending on pore structure. For this study, gas permeability and pore size were measured by capillary flow porometry, and classification of a novel method was performed to determine the type of pores (through pores, blind pores, and closed pores) based on International Union of Pure and Applied Chemistry (IUPAC). Gas permeability, through pore porosity, and pore size increased from heartwood to sapwood. The results of multiple regression analysis showed that through pore porosity, mean pore size, and bulk density were significant factors affecting gas permeability.
The effects of temperature on the product quality of wood pellet torrefaction were examined by performing experiments, proximate analysis, ultimate analysis, heating value measurement, ...thermogravimetric analysis, and moisture absorption of torrefied wood pellets at 250, 300, 350, and 400 °C. The liquids produced during torrefaction and high-temperature pyrolysis of torrefied wood pellet at 800 °C were also analyzed. By increasing the torrefaction temperature to 400 °C, the yield of the solid was decreased to 30.32%, with an increase in gas (17.53%) and liquid (52.16%) yield caused by the partial elimination and decomposition of hemicellulose, cellulose, and lignin of wood pellet. The higher heating value of wood pellets was increased from 4,670 kcal/kg for raw wood pellets to 7,480 kcal/kg for torrefied wood pellets at 400 °C with the carbon concentration during torrefaction. Although the carbon density and heating value of the wood pellets were improved, overall energy recovery efficiency was decreased because of the decrease in solid yield by torrefaction. Thermogravimetric analysis results suggested that thermally stable wood pellet formation is formed by the elimination and structural changes to hemicellulose, cellulose, and lignin. The hydrophobicity of wood pellets was increased by torrefaction leading to the elimination of the hydrophilic functional groups of wood pellets. The moisture absorption of wood pellets (14.95%) was also decreased to 5.09% for torrefied wood pellets. Low-temperature torrefaction between 250 and 300 °C produced the typical pyrolyzates of hemicellulose and cellulose, such as furans and acids. The amount of lignin pyrolyzates, such as guaiacol, eugenol, and other phenolics, was increased by applying high-temperature torrefaction at 400 °C. The solid fuel produced by the high-temperature torrefaction of wood pellets also provided a potential decreasing tar content during gasification, indicating the improved process efficiency of torrefied wood pellets.
We investigated the effect of ultrasonic treatment on Malas (
Homalium foetidum
) gas permeability and sound absorption coefficient using the transfer function method. Results showed a longitudinal ...average Darcy permeability constant of 2.02 (standard deviation SD 0.72) for untreated wood and 6.15 (SD 3.07) for ultrasound-treated wood, a permeability increase of 3.04 times. We also determined the average sound absorption coefficients in the range of 50 to 6.4 kHz and NRC (noise reduction coefficient: average value of sound absorption coefficient value at 250, 500, 1000, and 2000 Hz) of untreated Malas. Those values were 0.23 (SD 0.02) and 0.13 (SD 0.01), respectively, while those of ultrasonic-treated Malas were 0.28 (SD 0.02) and 0.14 (SD 0.02), a 19.74% increase in average sound absorption coefficient.
Among the various methods used to improve the sound absorption capability of wood, we focused on delignification in Indonesian momala (Homalium foetidum) and Korean red toon (Toona sinensis). We ...performed gas permeability, pore size, and porosity analyses and evaluated how the change in the pore structure affects the sound absorption capabilities. Results show that delignification increased the through-pore porosity and improved sound absorption capability in both species. In addition, the air gap in the rear space maximized the sound absorption of momala and the red toon. The noise reduction coefficient (NRC) of delignified momala (90 min) with a 3 cm air gap was 0.359 ± 0.023. This is approximately 154.6% higher than that of untreated momala without an air gap. The NRC of delignificated red toon (90 min) with a 3 cm air gap was 0.324 ± 0.040, an increase of 604.3% over untreated red toon without an air gap.
This study investigated changes in the sound absorption coefficients of three anatomical sections of cubed spruce (
Picea sitchensis
), Douglas fir (
Pseudotsuga menziesii
), and larch (
Larix ...kaempferi
) after microwave treatment. Microwave treatment at 1000 W and 2.4 GHz for 20 min increased the sound absorption coefficients (at 2000–5000 Hz) of spruce by 6.9% in the transverse section, 20.0% in the radial section, and 31.7% in the tangential section. The sound absorption coefficients of Douglas fir increased by 28.9% in the transverse section, 19.1% in the radial section, and 50.0% in the tangential section. Larch coefficients increased by 16.7% in the transverse section, 37.2% in the radial section, and 38.8% in the tangential section. The sound absorption coefficients of the softwoods differed according to species and anatomical plane after microwave treatment. It was concluded that changes in the measured sound absorption coefficient indicate alteration in the pore structure of wood, which can affect in turn wood permeability and impregnation. These data will be helpful for predicting the permeability and impregnation of wood after microwave treatment.
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