Volume 20 Issue 2

Increasing concerns regarding plastic waste and its impact on the environment have prompted a global trend to replace plastic films with fiber-based packaging solutions. Though the heat-sealing of polyolefin films provides a simple approach for realizing flexible packaging, paper does not have the natural attributes required for such applications. Therefore, paper sealability must be achieved by other means such as coating or varnishing. This study accordingly investigated the basics of imparting heat-sealability to packaging paper using overprint varnish applied with a lab coater simulating flexographic printing. The sealing and grease resistance properties of the resulting paper were compared with those of commercially available polyethylene dispersion-coated paper and oriented polypropylene/polyethylene laminate. The results confirmed that sufficient capabilities were realized using the proposed method; though the varnished paper exhibited a lower seal strength than the reference plastic films, it exhibited adequate properties for package sealing regardless of applied temperature. These observations were subsequently discussed to inform recommendations for further investigation and development.

The heat and sound insulation properties of the heartwood and sapwood of willow (Salix alba L.) were investigated.  Based on the experimental results, it was determined that the density value of the heartwood of the willow tree was higher than that of sapwood, while the moisture value was lower in the sapwood. The thermal conductivity coefficient was 0.090 W/m.K in sapwood and 0.103 W/m.K in heartwood; thermal transmittance coefficient was 3.954 W/m².K in sapwood and 4.738 W/m².K in heartwood. The sound absorption coefficient was highest in sapwood at 1000 Hz frequency level with 0.37, while the highest in heartwood was 0.50 at 800 Hz frequency level. These results would be useful in willow wood structural applications.

The seung instrument is played in one key (minor key) because the fret spacing creates a diatonic scale. Due to the fact that the frets are not uniformly spaced on the fretboard, the fret spacing produces a diatonic scale (do-re-mi-fa, etc.) instead of a chromatic scale of a guitar, where all the flats and sharps are available. The partial frequency (Hz) versus harmonic number for string 1 and 2 are very linear. The gradients of the linear equations fit very well with the fundamental frequency of the open string 1 and 2 and fret 1 to fret 9. The sounds were digitally captured using a PicoScope oscilloscope and were subsequently examined utilizing PicoScope software, emphasizing Fast Fourier Transform (FFT). The Time Frequency Analysis (TFA) was obtained via Adobe Audition. The notes for open string 1 and 2 are A4 followed by B4, C5, D5, E5, F5, G5, A5, B5, C6, and D4 followed by E4, F4, G4, A4, B4, C5, D5, E5, F5 from the 9 frets respectively. The 10 notes up to the 9^th frets for string 1 and 2 are A4 to C5 and D4 to F5 respectively.

Hot water-treated cow waste (HWTCW) was used as an efficient, low-cost, and sustainable adsorbent for the removal of cresol red dye and chromium(VI) from aqueous solutions. Functional groups present on the biomass surface were identified by Fourier Transform Infrared Spectroscopy as -OH, C=O, C=C, and C-O. The scanning electron microscopy analysis showed the structure relating to plant tissue and rough surfaces that were heterogeneous and irregular, revealing the origin of the biomass to be cellulose, lignin, hemicellulose, and other water-soluble components. Maximum adsorption capacity was attained at biomass dosage of 40 and 50 mg, 120 and 140 min as the time of contact, pH of 4 and 3, and temperature of 40 and 45 °C for CR and Cr (VI) adsorption. The equilibrium data from the adsorption of CR and Cr (VI) followed Langmuir and Freundlich models with maximum uptake of 73.3 and 66.4 mg/g. For the adsorption of CR by HWTCW, a pseudo-first-order kinetic model provided a better fit, whereas a pseudo-second-order model provided a better fit for Cr (VI) ions adsorption. The analysis of ΔH gave positive values of 22.4 kJ/mol for CR and 46.0 kJ/mol for Cr (VI) indicating the endothermic process.

The cooling of pellets is necessary because pellets reach 70 to 90 °C after the pellet press. The reduction in temperature solidifies the pellets, which increases the pellet quality and reduces the risk of self-heating during storage. Industrially, pellet plants use outdoor air in counterflow coolers and cooling ends when the pellet temperature is approximately 5 °C above ambient temperature. Cooling performed in the summer could result in high temperatures in the pellet stacks during storage, and cooling at low temperatures and high airflows in the winter could cause quality problems. Therefore, the aim was to determine how cooling air temperature, airflow, and storage time impact the durability, hardness, and off-gassing of the pellets. The results showed that the highest durability (97.7%) and hardness (310 N) were achieved when cooling with low-temperature air and low airflow. Additionally, durability and hardness stabilized at high values (98.9% and 640 N) after 30 to 40 days of storage, regardless of the airflow and cooling air temperature used. Furthermore, it was found that high airflows reduce off-gassing regardless of the cooling air temperature. It is recommended that the industry reduce airflow during the winter and increase it during the summer to produce high-quality pellets and minimize the risk of self-heating.