Volume 17 Issue 3

Purple nutsedge roots (Cyperus rotundus L.) and fenugreek seeds (Trigonella foenum-graecum L.) have been traditionally used as food and to treat common ailments. After extraction by solid-phase microextraction (SPME), the chemical structure of the revealed volatile fractions was researched with gas chromatography with mass spectrometry (GC-MS). The determined substances of the C. rotundus were pentadecanolide (72.0%), palmitic acid (8.2%), 16-hydroxy-6-hexadecenoic acid omega lactone (4.4%), and (Z)-anethol (3.9%). Most of the identified compounds of the T. foenum-graecum were pentadecanolide (61.3%) and (Z)-anethol (16.5%). The C. rotundus showed good antifungal activity against the yeast strands of Candida albicans and Candida krusei. Minimum inhibitory concentration (MIC) numbers were 250 and 125 µg/mL, respectively. However, the T. foenum-graecum seeds did not show any effect against the test microorganisms. The C. rotundus roots in particular exhibited good 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with an IC50 number of 0.91 mg/mL.

This preliminary study aimed to realize the potential use of titanium dioxide–carbonized medium-density fiberboard (TiO2–cMDF) as a biomaterial for dye wastewater treatment. TiO2–cMDF, which was prepared by carbonizing MDF treated with titanium tetraisopropoxide in isopropyl alcohol, was investigated for adsorption and then photodegradation of methylene blue (MB) under UV-A (390 nm, 19 W) and UV-C (280 nm, 12 W) light emitting diodes (LEDs). After two full cycles of adsorption, four successive cycles of photodegradation were conducted under UV-A LED. For every adsorption or photodegradation cycle, TiO2–cMDF practically removed MB. Both adsorption and photodegradation followed pseudo-first-order kinetics. The rate constants for adsorption decreased by half. The rate constants for photodegradation were similar. This finding suggests that UV-A LED is a robust and steady source of UV light. Photodegradation under UV-C LED was also performed. However, due to its high-energy output, the UV-C LED module overheated even though a cooling fan was present. Although the results indicate a slow photodegradation under UV LEDs, because of the limited number of specimens, increasing the number of specimens and UV LED modules will improve its performance.

Effects of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidation were evaluated for magnetic bio-nanocomposites of nanocrystalline cellulose (NCC). The magnetic bio-nanocomposites were prepared using NCC and nanomagnetite (NM) to produce organic compounds. The NCC was oxidized by sodium bromide (NaBr), sodium hypochlorite (NaOCl), and TEMPO. The oxidized NCC (ONCC) was characterized by Fourier-transform infrared spectroscopy (FTIR) and conductometry. The bio-nanocomposite particles from the NCC and the ONCC were prepared via in situ precipitation of iron salts from alkaline solution. The resultant bio-nanocomposites were coated on the surface of kraft paper. The magnetic bio-nanocomposite and coated papers were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The results revealed that the carboxyl groups were introduced successfully on the NCC surface. The bio-nanocomposite particles showed good dispersion in the surface of the papers. The saturation magnetizations of the coated papers with magnetic bio-nanocomposites of NCC and ONCC were 10.9 and 14.57 emu/g, respectively. The magnetic coated papers exhibited a superparamagnetic behavior. The strengths, apparent density, and air resistance of the coated paper with the ONCC bio-nanocomposites increased in comparison to the NCC coated sample, while the water absorption diminished due to the TEMPO-oxidation.

Hevea brasiliensis wood becomes residue at plantations in Malaysia. In this study, these residues were reinforced into silicone rubber to produce a new soft biocomposite (Hevea brasiliensis-silicone biocomposite). The newly introduced soft biocomposite has potential for use in cushioning and sealing applications. The specimens were prepared with five different compositions (0 wt%, 4 wt%, 8 wt%, 12 wt%, and 16 wt% fiber content). Tensile tests were conducted according to ASTM D412 (2008) to assess the mechanical properties. Morphological characteristics were analyzed from the fractured surface of specimens. Stress-stretch data was used to quantify the non-linear tensile behavior, which was based on Neo-Hookean, Mooney-Rivlin, and Ogden hyperelastic constitutive equations. An increase in fiber content improved the modulus of silicone rubber. However, it reduced the flexibility and elastic properties of the silicone rubber biocomposite. The increasing material constant values supported these findings. The hyperelastic models accurately represented the behavior of the Hevea brasiliensis-silicone biocomposite. This study contributes knowledge towards a better understanding of the mechanical behavior of Hevea brasiliensis-silicone biocomposites.

This study elucidated the mechanical performance of different connections used in orthogonal ribbed beams made of poplar laminated veneer lumber (LVL). Three types of connections (namely, U-, T-, and L-shape) were fabricated and used to connect the second beam and the middle part of a main beam to form an orthogonal rib beam. A concentrated load was applied to the intersection between the main beam and the second beam. The results showed: (1) all three types of ribbed beam connection specimens showed good connecting performance and the ductile failure, including the pull-out of partial self-tapping screws, crushing of LVL at the end of the ribbed beam, and connection failure; (2) the variation of load capacity of JD2-type specimens was approximately 3.2%, which was smaller than that of the JD1- and JD3-type specimens, slightly less than 10%; (3) the ultimate bearing capacity of a connection specimen was proportional to the number of self-tapping screws; and (4) the mechanical performance of the U-shaped connection specimens was worse than that of the L-and T-shaped connection specimens. The L-shaped connection was recommended due to its better mechanical performance, simpler configuration, and more convenient fabrication.

Ketones are an important class of multi-purpose products used for the production of high value-added chemicals. Herein, a novel method for the generation of methylcyclopentenone and pyridone via the modification of a magnesium aluminum spinel catalyst is proposed. In this study, zinc oxide, magnesium aluminum spinel, and ZnO-loaded magnesium aluminum spinel were used as catalysts for the catalytic pyrolysis of rape straw, corn stalk, and camphorwood powder at different reaction temperatures. Experimental results showed that different experimental temperatures and catalyst types played a crucial role in the formation of methylcyclopentenone and pyridone. Catalytic pyrolysis of rape straw with ZnO-loaded magnesium aluminum spinel increased the yield of methylcyclopentenone by greater than 6-fold compared to the yield without the catalyst, and the catalytic pyrolysis of corn stover increased the production of pyridone to 12.4%. The increase was primarily attributed to the conversion of cellulose and hemicellulose to ketones promoted by the ZnO-loaded magnesium aluminum spinel. These findings demonstrated that ZnO-loaded magnesium aluminum spinel catalysts can provide a new approach for enhancing the yield of methylcyclopentenone and pyridone during biomass fast pyrolysis.

In order to solve the difficulties with the observation of the ablation zone and the many factors that affect the dynamic evolution process of the ablation zone, the structural morphology and dynamic evolution process of the ablation zone in the process of water-jet assisted laser machining Korean pine (Pinus koraiensis) were studied. Based on the DFLUX subprogram, a compound heat source model was established. Under the comprehensive consideration of heat conduction, heat convection, heat radiation, and thermal physical properties varying with temperature, the three-dimensional (3D) finite element model of the Korean pine was numerically simulated by water-jet assisted laser machining. Through numerical simulation analysis, the cross-sectional morphology of Korean pine kerf was found to be screw-shaped, and the experimental results were in good agreement with the simulation results. The dynamic evolution law of water-jet assisted laser machining of Korean pine was obtained. In addition, as the laser power increased and the cutting speed decreased, the morphology of the Korean pine kerf remained unchanged, but the structure size of the Korean pine kerf showed an increasing change.

A fibrillated lyocell fiber-based separator was prepared using lyocell fibers and was modified with cellulose nanofibers. The effects of the cellulose nanofiber addition on the tensile properties, electrical properties, pore structure, liquid absorption properties, and equivalent series resistance of the separators were studied. It was found that adding an appropriate amount of cellulose nanofibers to the fibrillated lyocell fiber separator can improve the tensile strength, elongation at break, breakdown voltage, and equivalent series resistance value of the separator; reduce the pore size and porosity of the separator; and improve the pore size distribution. Moreover, the separator modified with 4% cellulose nanofibers yielded a favorable combination of properties, with a tensile strength of 0.645 kN/m, a mean flow pore diameter of 0.771 μm, a porosity of 88.4%, a capillary rise in paper of 30.7 mm/10 min, and an equivalent series resistance value of 2.46 Ω.

Thermo treatment on veneer has been recognized as environmentally friendly and can modify wood properties. The objectives of this study were to investigate mass loss of thermo-teak veneer, to assess the density changes, and to examine shrinkage based on different levels of temperature at different time lengths. The temperatures were 180, 200, 220, and 240 °C applied at three different lengths of time, i.e., 4, 8, and 12 min on teak veneer sheets. The results showed that the mass loss at the temperature of 180, 200, 220, and 240 °C were not significantly different. Density changes were significant depending on the level of temperatures. Percentage of density decrease changed from 3.85% to 15.69% at temperatures ranging from 180 to 240 °C but the length of time (4, 8, and 12 min of thermal treatment) did not have a significant effect. The mass loss ranged from 5.90% to 17.66%.

Effects of heat treatment parameters on the physical properties, mechanical properties, and crystallinity index of Scots pine and beech wood were investigated. Scots pine (Pinus sylvestris L.) and beech (Fagus orientalis Lipsky) sapwood samples were prepared in 2 cm × 2 cm × 36 cm dimensions by considering the physical and mechanical tests. The samples were heat-treated for 2 h and 4 h at 150 °C, 180 °C, and 210 °C in an atmospheric environment. The shrinking and swelling percentages of all samples were calculated. The compressive strength, bending strength, modulus of elasticity (MOE), and hardness tests were carried out. X-ray diffraction (XRD) was performed to calculate the crystallinity index values. As a result of the study, it was determined that heat treatment generally had a positive effect on the physical properties of Scots pine and beech samples. It was observed that the bending strength of the wood samples decreased up to 180 °C as the temperature increased and then increased. It was determined that the MOE of the Scots pine and beech wood decreased with the heat treatment. As the heat treatment temperature and time were increased, the crystallinity index values initially increased partially and then decreased.