Volume 15 Issue 4

This research investigated the potential of some European wood species for use in the manufacturing of the back plates of violins as an alternative to the quite rare curly maple wood. An experimental modal analysis was employed for this purpose using the impact hammer method. The modal analysis was performed both on the top and back plates, as individual structures, and then after being integrated into the violin body. The modal analysis envisaged the determination of the eigenfrequencies (natural frequencies), the number of spectral components, and the quality factor, as important indicators of the acoustic performances of a musical instrument. A multi-criteria analysis based on the values obtained for these indicators allowed interesting findings concerning the acoustic properties of the selected wood species (hornbeam, willow, ash, bird-eye maple, walnut, and poplar). Same as curly maple, they all have special aesthetics, but only hornbeam, willow, and ash wood proved to have acoustic potential as well.

The consumption of renewable energy sources results in the minimal production of greenhouse gases. However, the issue of environmentally efficient use of renewable energy sources remains a key concern. The primary aim of this article was to assess whether the energy production from renewable energy sources was environmentally efficient in four selected European countries: Germany, Austria, Poland, and the Czech Republic. In order to achieve the primary research goal, a regression analysis method was used for several variables. The results of the analysis suggested that with an increase in the consumption rate of renewable energy sources and biofuels equivalent to one thousand tons of oil, the volume of emissions from all sectors would increase by 0.0048 thousand tons (4.8 tons) on average. The system of emission allowances was rather environmentally inefficient at the lower allowance levels; in the monitored period of 2007 to 2016, the dependence of greenhouse gas production on the consumption of fossil fuels did not statistically manifest itself. Based on the analysis, the land use, land-use change, and forestry production activities do not contribute to increasing total greenhouse gas emissions.

The objective of this research was to characterize the cotton stalk resource. This paper also focused on the manufacturing of formaldehyde-free particleboards using whole cotton stalk. The effects of opening particle sizes and cotton ball residue ratios on performance properties of manufactured particleboard was assessed. Modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), and thickness swelling (TS) were characterized. Particleboards manufactured from four different opening particle sizes (6, 8, 10, and 20 mm) using an emulsifiable polymeric isocyanate adhesive (eMDI) were investigated. Similarly, the same performance properties were evaluated using four different cotton ball residue ratios (0, 5, 10, and 15 wt%). Results showed that the stem length and diameter of cotton stalks cultivated in Queensland (Australia) vary greatly and range from 160 to 890 mm and 5.03 to 10.88 mm, respectively. The highest weight proportion of the resource is the cotton stem making up 46 wt% of the available resource. The highest average values of MOR, MOE, IB, and the lowest TS were observed for boards with an opening particle size of 8 mm. The cotton ball residues had detrimental effects on the mechanical properties with a decrease in properties observed with increasing cotton ball residue load.

The discovery of new methods to control porosity and microarchitecture may lead to the refinement of carbon materials from lignocellulose as advanced functional materials. However, the high ash content on the surface of lignocellulosic biomass reduces the surface area and adsorption properties of the activated carbon. This study presents a novel approach, using a deashing post-treatment as the pore generator, to increase the quality of the activated carbon. The micropore capacity was improved by deashing post-treatment with distilled water, where 80% of the total pore ratio of the activated carbon was occupied with micropores. Ultrasonic treatment was able to penetrate deeper into the structure of coconut shell activated carbon, creating cavities and pores, thus increasing the surface area. Understanding the effects of these new controlling methods on pore refinement can elucidate the microporous fabrication of other activated carbons from high ash-content lignocellulosic biomass.

Coal gangue and sunflower straw biomass from Xilingguole, Inner Mongolia, China and Ulanqab Tsining District, Inner Mongolia, China, respectively, were burned separately and mixed in different proportions. The synergistic effect was analyzed by comparing the actual mixed combustion curve with the theoretical mixed combustion curve. The bar chart and TR (the mean of the difference between the experimental and calculated was divided by the mean of the calculated values) value curve were used to show the synergistic effect. The results showed that the synergistic effect of coal gangue and sunflower straw was optimal when the ratio (sunflower straw:coal gangue) was 2:8.

Wood particles and a mixture of forest waste were investigated as raw material for the particleboard industry. Urea formaldehyde resin was used as the adhesive in the production of the particleboards. Some chemical (pH, dilute alkali solubility, hot and cold water solubility), physical (density, moisture, thickness swelling, and water absorption), mechanical (modulus of rupture, modulus of elasticity, internal bond strength, and screw holding strength) properties, as well as the contact angle values of the resulting particleboards were determined. Due to its needle litter and cone content, the forest waste exhibited a lower pH value and a higher content of extractive material than wood. Increasing the addition of forest waste led to significant reductions in the physical and mechanical properties of the particleboards. The addition of forest waste reduced the internal bond strength the most (56.6%), whereas the least reduction (15.7%) was in the value of screw holding strength perpendicular to the surface. The values of all panels except panel type F exceeded the minimum modulus of elasticity (1600 N mm-2) required for furniture production according to the EN 312-P2 standard. Results of the analyses showed that forest waste (10% and 20%) is a suitable renewable raw material source for panel production.

The pulp and paper industry contributes to the economic development of the U.S., producing goods that meet primary needs. However, this sector must operate in a balance with the environment to ensure ecological preservation. Proposing a non-radial slacks-based measure – data envelopment analysis (SBM-DEA) approach, this study assessed the environmental efficiency of the pulp and paper industry in the U.S. from 2015 to 2018. External environmental impacts and random interferences on efficiency assessment were explored by using a stochastic frontier approach (SFA) regression. This study revealed that the U.S. pulp and paper industry was highly non-eco-efficient in the period evaluated, presenting an average environmental efficiency value of 0.509. Also, it is suggested that a total of 2.967 million metric tons of CO2eq emissions were in excess of those that were estimated based on an assumption of perfect environmental efficiency from 2015 to 2018 in the U.S. pulp and paper Industry. Based on the analysis of input and output slacks and the external environmental factors which reflect the environmental features of each decision-making unit (DMU), these facilities should substantially reduce CO2eq emissions and enhance the resources-allocation efficiency for improving the environmental efficiency of the U.S. PPI.

The dielectric behavior and properties of three types of Sarawak woods, under various conditions (untreated, alkaline treated, potassium carbonate treated, and heat treated), were investigated and discussed. The dielectric constant, loss, and dissipation factor tests were conducted via a dielectric impedance analyzer. The results revealed that the dielectric properties decreased in relation to an increase in frequency. With considerations to the treatment method, the highest dielectric constant values for the untreated samples were found in Kumpang wood, the highest dielectric constant values for the heat-treated samples and potassium carbonate treated samples were found in Keranji wood, and the highest dielectric constant values for sodium hydroxide treated samples were found in Kayu Malam wood. Therefore, it was evident that the physical properties, e.g., internal structure, density, moisture, temperature, etc., could affect the dielectric behavior and properties of the wood materials.

A series of novel benzofuran-1,2,3-triazole hybrids were synthesized and investigated as fungicidal preservatives. The compounds were evaluated for their antifungal potential against white-rot (Trametes versicolor), dry brown-rot (Poria placenta), and wet brown-rot (Coniophora puteana and Gloeophyllum trabeum) fungi, at different concentrations (500 ppm and 1000 ppm). The tests of the final products (8a, 8b, 8c, 8d, 8e, 8f, and 8g) demonstrated that compound N-((1-(4-fluorobenzyl)-1H-1,2,3-triazol-4-yl)methyl)benzofuran-2-carboxamide (8f) at a concentration of 500 ppm was the most active against wet brown-rot C. puteana (23.86% inhibition) and G. trabeum (47.16% inhibition) fungi. However, testing demonstrated that compounds 8a, 8b, 8c, 8d, and 8g at a concentration of 500 ppm did not exhibit acceptable antifungal effects against white-rot T. versicolor and dry brown-rot P. placenta fungi.

Bar angle is one of the most important parameters of an isometric straight bar refiner plate and its effects on the change in pulp and paper properties during refining is still unclear. This study investigated the effect of plate bar angle on refining quality and refining efficiency by clarifying the definition of bar angle. Five isometric straight bar plates with different bar angles were used in low consistency refining of bleached sulphate eucalyptus pulp (BSEP). Samples at different refining time intervals were collected, and the fibers, pulp, and paper properties were detected and analyzed. There was a great influence of bar angle on the fibers, pulp, and paper properties. Additionally, a critical static attack angle, or critical bar angle for plates with specific field angle, existed. The modification of fibers and pulp properties was strong when the plate reached a critical bar angle. Meanwhile, there was an optimal static attack angle for a plate with specific field angle, when considering paper properties such as tensile index and tear index. The refining time was shortest when the pulp was refined by the plate with critical bar angle, allowing the paper properties to reach a maximum value. It was shown that the static attack angle of refining should be selected in the range of 45º to 70º, which includes the optimal value and the bar angle was proposed in the range of 11.25º to 23.75º for the plate with common field angle of 22.5º.