Volume 20 Issue 1

Thermomechanical pulp (TMP) was bleached with an ozone–hydrogen peroxide system, with the addition of hydrogen peroxide and ethylene glycol to enhance bleaching efficacy. The ISO brightness of TMP increased proportionally with higher concentrations of hydrogen peroxide across all sequences. Notably, TMP treated with the ozone and hydrogen peroxide sequence (ZP sequence) exhibited ISO brightness levels comparable to those of TMP bleached with hydrogen peroxide alone. However, the addition of hydrogen peroxide during the Z stage of the pZP sequence resulted in a 2.4% increase in ISO brightness and enhanced lignin solubility. A brief alkaline extraction step in the pZEP sequence led to a significant 4.3% increase in ISO brightness, though this improvement was accompanied by a yield loss due to removal of lignin in the E stage. Furthermore, the addition of polyethylene glycol alleviated yield loss by enhancing the selectivity of ozone bleaching, while effectively maintaining a stable ISO brightness.

The objective of this study was to investigate the sound absorption efficiency of plywood-carbon fiber composite materials and evaluate their potential as acoustic panels. In this work, plywood and plywood-carbon fiber composite materials were produced using Uludağ fir (Abies nordmanniana subsp. bornmülleriana Mattf.) peeling veneer, woven carbon fiber, and polyvinyl acetate (PVAc) adhesive. Three experimental groups and a control group were created. The materials from plywood-carbon fiber composite were manufactured in three different designs to form experimental groups. The sound absorption coefficients of the plywood and the composite materials were tested via the impedance tube method, according to ASTM standard E1050-98 (2006). Attention was paid to the acoustic behavior at low (bass) frequencies (63 Hz to 250 Hz), mid frequencies (315 Hz to 1600 Hz), and high (treble) frequencies (2000 Hz to 6300 Hz). It was determined that the plywood-carbon fiber composite materials could reflect or transmit sound waves at low (bass) frequencies, while significantly absorbing sound waves at high (treble) frequencies. It can be suggested that plywood-carbon fiber composite materials could be used as sound absorbing acoustic panels.

A wood species classification scheme was developed based on open set using an improved Nearest Non-Outlier (NNO) classifier. Near infrared (NIR) spectral curves were collected in spectral band 950 to 1650 nm by a micro spectrometer. The spectral dimension reduction was performed with a Metric Learning (ML) algorithm. Two improvements were proposed in the following NNO classifier. First, a cluster analysis was performed in each wood class by using a Density Peak Clustering (DPC) algorithm to get 1 to 3 clusters. A fixed threshold  for all wood classes was replaced by a variable  for all clusters. This threshold  defines an internal boundary for one wood species to further compute a class membership score for all wood species. The classification accuracy based on these clusters of each wood class was better than that based on each class. The experimental results in different open set scenarios demonstrate that the improved NNO classifier outperformed the original NNO classifier and some other state-of-the-art open set recognition (OSR) algorithms.

Osteoarthritis (OA) is characterized by inflammation of the synovial joints. However, the drugs used to treat OA are insufficient due to multifactorial pathogenesis of the disease. The present study determined the anti-inflammatory and antioxidant effect of Akebia quinata D. aqueous extract (AQDE) against osteoarthritis using in vitro and in vivo models of OA. Initially, the effect of AQDE was identified to determine its effect on the various biomarkers of the TNF-α mouse chondrocytes. The results suggest that AQDE causes significant ACGAN and COL2 and reduction in IL-1B, IL-6, MMP-13 and PTGS2. It also causes induction of the expression of Bcl2, CDK1, CCND, and reduction in the rate of apoptosis of mouse chondrocytes. In the in vivo rat model, AQDE improved mechanical allodynia in the Von Frey test and reduced knee joint swelling. Micro-CT scanning showed improvement in bone erosion. The level of oxidative stress (MDA, SOD, and GSH) and production of pro-inflammatory cytokines (IL-1B, and IL-6) was restored to near-normal levels in a dose-dependent manner. AQDE reduced the mRNA expression of COX-2 and NF-kb in both in vitro and in vivo study. The results demonstrated the significant pharmacological activity of AQDE against osteoarthritis in both in vitro and in vivo model.

Laminated veneer board (LVB) panel from gmelina wood is one form of developing processed wood products to improve the quality of laminated veneer lumber (LVL). The addition of fire-retardant materials is an important element that needs to be developed to increase the fire resistance properties of LVL and LVB panels. The fire-retardant materials used in this research were diammonium phosphate (DAP) and sodium silicate (SS) with a concentration of 20% each, using two different application methods, namely impregnation and coating. This research aimed to determine the effect of adding 20% ​​DAP and 20% SS solutions on physical and mechanical characteristics, formaldehyde emissions, delamination percentage, and the burning time for LVB panels. Panel testing is carried out referring to the requirements of the ASTM D-143:2003 test standard for density, BS EN 317:1993 for swelling-shrinking, JIS A 1460 (2001) for formaldehyde emission, and JIS 701 (2008) for other parameters. Results from physical and mechanical tests showed that panels already met the standard. Formaldehyde emissions were less than 0.4.mg/L classified F**** which means the panel is safe and environmentally friendly. Percentages delamination already met the standard except for both SS impregnation and SS coating application methods. The longest burning time was achieved by the panel with added DAP impregnation.

The effects of nano-sized carbon black (CB), ammonium polyphosphate (APP), and microcrystalline cellulose (MCC) were tested relative to the mechanical and thermal properties of polypropylene (PP)-based composites. Composites were produced by injection molding in nine different combinations by adding materials at the levels of 0% or 10% MCC, 0% or 15% APP, and 0% to 7% CB. With the use of APP, there was a decrease in tensile and flexural strength, while there was an increase in impact resistance. Compared to the control group, it was determined that with the use of CB and MCC, there was an increase in tensile modulus, flexural strength, flexural modulus, and impact strength, while there was a decrease in tensile strength and elongation at break values. The flexural strength and flexural modulus values of all PP composites were higher than the standard values for polyolefin-based plastic lumber decking boards. A decrease in the initial degradation temperature occurred with the addition of MCC. As the CB usage was increased and MCC was added, the amount of charred residue increased. Additionally, the use of CB and the addition of MCC increased the maximum and final degradation temperatures compared to the control sample. Considering the results obtained, it was concluded that the use of CB and MCC generally improved the mechanical and thermal properties of PP composites.

Bamboo activated carbon (BAC) was prepared and used for wastewater treatment. Its adsorption capability was investigated using control charts. The fishery industry wastewater in Jeli was sampled for 45 days. The adsorbent, i.e., 45 μm BAC was prepared through the pyrolysis process with chemical-physical activations at 600 °C for 6 hours. The BAC was mixed thoroughly with the fishery industry wastewater, and the mixture was then separated by filtration. The effectiveness of wastewater treatment by BAC was determined using the water quality index (WQI), and the BAC adsorption process was monitored using the Shewhart individual and moving average (MA) charts. The charts’ performance in detecting off-target processes present in the BAC wastewater treatment process was also determined. The WQI was shown to improve significantly after BAC treatment, with all values exceeding 60, surpassing the water pollution index threshold (≤ 60) set by Malaysia Department of Environment (DOE). The Shewhart individual and MA charts were able to detect the out-of-control condition(s). By comparison, the Shewhart individual chart demonstrated a preferable performance. This work paves the way for quality practitioners to properly utilize control charts to produce a more efficient wastewater treatment approach using BAC and to acquire statistical quality control.

Thinning silviculture is a forestry measure that can improve forest ecosystems and stand structure. Thinning can impact the properties and quality of poplar wood. This study investigated the effects of three different thinning intensities on the fiber morphology and crystallinity of poplar wood, providing a theoretical basis for the cultivation and rational processing of poplar plantations. The results indicated significant differences in the proportion of wet heartwood area among different thinning intensities. With increased thinning intensity, the wet heartwood area proportion rose, while it decreased with wood height under the same thinning intensity. Fiber length increased with thinning intensity, reaching a 16% increase at 50% thinning, as well as with sampling height. Fiber width grew with thinning intensity, initially widening, and then narrowing with height. Cell wall thickness first increased and then decreased with thinning intensity, peaking at 50% thinning. The fiber length-width ratio increased with thinning intensity and initially increased then decreased with height. The fiber-diameter-cavity ratio also increased with thinning intensity and height. Crystallinity showed a trend of first increasing and then decreasing with tree height, peaking at breast height, and it was higher in normal wood than in wet heartwood under the same thinning intensity.

Fructose, glucose, and sucrose were converted to organic acids in the presence of aqueous aluminum nitrate (Al(NO₃)₃) to develop a technically viable route for upgrading sugarcane molasses. Reactions were carried out in a microwave reactor and a muffle oven with conventional heating (convective heat transfer) using a sealed glass tubes and a hydrothermal stainless-steel autoclave as reaction vessels, respectively. Conversion was evaluated for different reaction times and temperatures. Lactic acid predominated as the product from the retro-aldol chain splitting of fructose, reaching a 67.5 % molar yield using 2.67 mmol·L^-1 Al(NO₃)₃ (4 wt% based on the carbohydrate dry mass) in a stainless-steel reactor with conventional heating. Sucrose required hydrolysis, glucose isomerization, retro-aldol chain splitting, dehydration, tautomerization, and 1,2-H migration to produce lactic acid in molar yields approaching those obtained from fructose (65.5 %). Besides lactic acid, formic and levulinic acids were produced in variable amounts through a fructose dehydration pathway, having 5-(hydroxymethyl)-furfural (HMF) as reaction intermediate. The use of a stepwise heating regime was a critical parameter to achieve high product yields and good lactic acid selectivity in these reaction systems.

As interest in the use of eco-friendly enzymes increases in the paper industry, an energy-intensive industry, the development of a wide range of enzyme application technologies is required. This study evaluated the effects of cellulase on the refining efficiency, fiber properties, and sheet strength of softwood bleached kraft pulp (Sw-BKP). The pulp was enzyme-dosed with cellulase for 6 h and refined using a laboratory beater for 15 min. The freeness and physical properties of the Sw-BKP fibers were analyzed. The pulp freeness decreased linearly as the refining time and enzyme dosage increased, indicating that the cellulase promotes refining efficiency by inducing fiber shortening and internal fibrillation during refining. Handsheets were prepared from 15-min refined enzyme-dosed and non-enzyme-dosed Sw-BKP. The strengths of the enzyme-dosed handsheets were lower than those of the non-enzyme-dosed handsheets because fiber shortening due to the cellulase activity was dominant during the refining. Therefore, cellulase effectively reduces refining energy consumption. However, it is essential to determine the correct enzyme dosage and refining time to balance the desired refining energy reduction with the resulting paper strength.