Volume 13 Issue 3

The best extraction characteristics and optimal parameters for the steam-distillation extraction of bamboo leaf hydrosols were investigated to provide a data foundation for the subsequent study of bamboo leaf hydrosols and their industrial applications. The colligation score (CS) of the bamboo leaf hydrosols antioxidant activity (based on its DPPH free radical scavenging ability and total antioxidant capacity) was used as an evaluation index. The extraction time, crushing degree, and solid-to-liquid ratio were selected as the extraction parameters and response surface methodology was used to optimize the extraction process. The CS and sensory evaluation were used to determine the best distilled volume of bamboo leaf hydrosols. The results showed that the prepared bamboo leaf hydrosols had a high CS of 0.9967 (the DPPH free radical scavenging capacity was 0.052 mg/mL Vc equivalent, and the total antioxidant capacity was 0.2771 mg/mL Trolox equivalent) when the bamboo leaf crushing degree was 10 mesh, the solid-to-liquid ratio was 1:25, and the extraction time was 6 h. When the distilled volume was one-quarter of the total aqueous extract volume, the bamboo leaf hydrosols were highly active, colorless, and had a pleasantly aromatic odor.

This work highlights the synthesis of high purity silica from rice husks and the effect of rice husk silica (RHS) loading on the mechanical, physical, and thermal properties of natural rubber (NR) compounds. The RHS was synthesised using the solvent-thermal extraction method, which was adopted from TAPPI T204 (2007) and TAPPI T264 (1997) standards with some modifications. The treatment successfully produced high purity RHS particles, with 99.9% SiO2 content between 100 to 300 nm in size. The high purity RHS was then incorporated in NR compounds at 2, 4, 6, 8, and 10 parts per hundred rubber (phr). Even without any surface modification, the high purity RHS-filled NR compounds showed tremendous improvements in strength-related properties at the optimum loading of 4 phr. In addition, the thermal stability of the NR compounds was remarkably improved with the addition of RHS.

The article presents research on the effect of the sharpness angle on the quality of machined surface of native wood species (pine, beech, and black locust) and an exotic species called iroko. Four sharpness angle values were analyzed at 25, 40, 45, and 55°. The experiment was conducted on a bottom-spindle milling machine, with a constant spindle rotational speed (6000 min-1) and four feeding speeds of 3.2, 8.3, 12.5, and 16.7 m/min. The influence of sharpness angle, feeding speed, and wood species on the quality of machined surface of wood was determined. The optimum ranges of the sharpness angle were established with respect to wood surface quality. The surface roughness of the samples decreased with decreasing in the sharpness angle in range of 55° to 40°. The optimal value of the angle was 40°, and the roughness increased with increasing feeding speed. It was found that an increase in wood density decreased surface roughness.

The aim of this paper was to investigate the influence of zinc oxide (ZnO) nanoparticles on the resistance of pine wood to fire and ultraviolet (UV) radiation. The ZnO nanoparticles were prepared from aqueous zinc nitrate via a proteic sol-gel method. Dried samples were impregnated using immersion in an aqueous solution of ZnO nanoparticles in the amount of 1 wt.% wood. Samples were exposed to an open flame to test the fire retardance, and a high-pressure UV lamp was used to test the UV resistance. The results showed an improvement in the fire retardance and UV radiation resistance after the impregnation of ZnO nanoparticles.

Effects were compared for three low-cost pretreatment methods (dilute acid, alkali, and steam explosion) relative to the effectiveness of environmentally friendly enzymatic hydrolysis and ethanol fermentation of aspen, birch, and oak chips. The highest monomeric sugar yield was achieved with the alkali pretreatment of the aspen chips (22 g/L of glucose and 6 g/L of xylose). Additionally, the concentration of lignocellulose degradation products formed during this pretreatment was relatively low, and so the hydrolysis and fermentation efficiencies were 80% and 85%, respectively. The application of dilute acid pretreatment led to lower yield of enzymatic hydrolysis in comparison with alkali pretreatment, resulting in 41% to 62% of theoretical yield for aspen and birch chips, respectively. Increasing the NaOH concentration led to an increase in the monomeric sugar yield, and consequently increased the hydrolysis and fermentation yields. By contrast, increasing the acid concentration resulted in a higher sugar yield, and the fermentation efficiency decreased. The applied steam explosion conditions resulted in the formation of 6.8 to 15.4 g glucose/L, with hydrolysis yield in the range 34 to 42% of theoretical. The most susceptible for pretreatment and enzymatic hydrolysis was found to be aspen biomass.

In the industrial processing of logs, large amounts of bark can be utilized as pellets. This study sought to establish conditions for the efficient use of bark, in the form of pellets, as a solid, renewable fuel. First, the physical properties of the bark (10% moisture content, 618-kg/m³densityfor aspen, and 749-kg/m³ density for birch) and pellets obtained from the shredded bark were determined. Then, the calorific properties (calorific value, calorific density, and ash content) of the shredded native bark and bark treated at 180 °C, 200 °C, and 220 °C for 1h, 2h, and 3 h were determined. The sawdust samples that underwent the torrefaction treatment were analyzed to find the mass loss. The mass losses of the birch bark were 20.0% (native bark) to 39.0% after a heat treatment at 220 °C for 3 h. An increased calorific value, up to 9.6%, showed that both the temperature and duration of the treatment improved the calorific properties of the bark. The findings of this paper highlighted the fact that bark can be used as a fuel source in log processing factories.

Under the premise of an unchanging total thickness in cross-laminated timber (CLT) made from Chinese fir, research into the effect of different CLT laminate thicknesses on the mechanical performance (bending and shear performance) was performed using the existing CLT static analysis theory to calculate and compare the bending performance of CLT specimens. The results showed that at constant total thickness the bending performance increased, the shear performance worsened, and the destruction mode of the CLT structure became simpler with an increase in the CLT laminate thickness. Increasing the odd to even layer thickness ratio effectively improved the bending and shear performance of the CLT specimens for a certain percentage range.

To improve the whiteness of fly ash, fly ash was prepared using calcium hydroxide, water, and carbon dioxide as the reaction system to coat calcium carbonate crystals on the surface of the fly ash. This study investigated the effect of the calcium hydroxide content and stirring rate on the crystallization of the calcium carbonate on the fly ash surface. The results showed that the calcium carbonate nanoparticles prepared with a 7% calcium hydroxide concentration and stirring rate of 500 rpm were coated on the surface of the fly ash, and the whiteness of the modified fly ash reached a maximum of 59.7% ISO. The microscopic process of heterogeneous nucleation of calcium carbonate and the LaMer model were explored to explain the influence of the precursor reactant concentration and stirring rate on the nucleation and growth of the crystal.

In order to determine the possibility of whole-tree wood utilization of a native tree species in Northeast China (P. ussuriensis), this study investigated the air-dried wood density and fiber dimensions for each ring in the branch, stem, and root wood of the tree species. The results showed significant differences in wood densities and fiber dimensions among tree positions (p <0.05). The root had the highest average density (0.596 g/cm3), and branch had the lowest average density (0.506 g/cm3). The root and branch wood exhibited larger fibers than that of the stem wood. The root wood had the highest average fiber wall (6.038 µm). The fiber wall of branch wood appeared thinner than the stem wood, although the difference was not statistically significant. The radial pattern of wood density and fiber dimensions indicated that branches and roots did not have juvenile wood such as was found in the stems. The study concludes that the use of branch or root wood of P. ussuriensis would be favorable for papermaking or wood-based panels.

The promotion of sustainable economic development and issues related to ecological and environmental protection has led to a common interest in the use of raw materials from renewable sources. Recently, there have been many scientific works on the use of different natural wastes as components in the production of new composite materials and polymers. An example of natural waste that is not managed efficiently is grain husk, which is a by-product of the production of flour and other products. This work studied the use of wheat grain husk for plastic processing. A short review is presented of studies concerning the use of natural waste and materials as fillers for natural and synthetic polymers, as well as their potential applications. The authors conducted original research on the influence of the mass fraction and particle size of wheat bran on the selected properties of low-density polyethylene, which can be useful in the evaluation of the suitability of this raw material for particular technical applications.