Volume 13 Issue 4

The complexity of the cutting zone makes it impossible to establish a reliable, simple, and comprehensive mathematical model for orthogonal wood cutting. Thus far, the science of cutting materials have used only approximate and simplified engineering theories that attempt to explain the mechanisms of chip shaping. The research of wood processing by chip separation is mostly based on models developed for metal processing. By applying Astakhov’s model to orthogonal wood cutting, the total cutting power is divided into four components, and each cutting force component can be theoretically related to the coefficients of chip compression.  In the present study, longitudinal, and tangential coefficients of chip compression were determined experimentally during orthogonal cutting of wood in the longitudinal (0 – 90) direction depending on wood moisture content (MC) and cutting speed. The direction of the fibers, cutting speed, and MC influenced the ​​ coefficient of chip compression. The MC of wood above the fiber saturation point significantly changed the impact of the cutting speed on the tangential coefficient of chip compression. In order to explain and better understand the obtained results of chip compression coefficients, the modulus of elasticity (MOE) of wood samples with different MC was determined. The MOE was calculated from the compression tests on small specimens in tangential and longitudinal direction.

High phosphate solubility is one of the most important factors for increasing plant growth. This study focused on the zinc phosphate (ZP) solubilizing capacity of thermo-halotolerant Aspergillus terreus, where the growth showed halo zones on Pikovskaya agar medium that appeared at high NaCl concentrations (up to 10%) and a wide range of temperatures (up to 45 °C). Acidification of the broth was assumed to be the major mechanism for ZP solubilization by A. terreus, where the growth was related to the pH decrease in the medium containing ZP. Under pot conditions, A. terreus increased the biomass and phosphorus content of Hordeum vulgare plants. A. terreus showed a phosphorus solubilization ability with a NaCl concentration of up to 10%; therefore, A. terreus can be of great benefit in maintaining the available phosphate levels for crops in saline soils. Finally, it was found that A. terreus with ZP can substitute chemical fertilizer and help improve crop production.

A novel composite catalyst consisting of nickel, cerium, and carbon nanotube (CNT) was developed for native lignin and industrial lignin depolymerization. It was found that Ni and Ce had synergistic effects on the depolymerization. Native lignin was depolymerized to monophenols with a yield of 21.4% at 300 °C for 2 h under 2 MPa hydrogen pressure with serious coke formation. A milder condition set at 280 °C for 2 h under 2 MPa hydrogen pressure provided a monophenols yield of 13.5% with 78.6% lignin removal, but much less coke formation and better catalyst reusability. Even after running the trial four times, the catalyst presented high efficiency. Industrial lignin was depolymerized to oligomers, which are a series of aromatic micromolecules that could be extracted by specific organic solvents such as ethyl acetate. Those oligomers could be used as high calorific value bio-oil. After being depolymerized at 260 °C for 1 h under 2 MPa hydrogen pressure, the yields of oligomers were 56.0% and 11.6% extracted by ethyl acetate (EA) and petroleum ether (PE), respectively. After recycling four times, the catalyst still exhibited high activity. It was clear that the Ni/Ce-CNT was an effective catalyst in lignin depolymerization.

Wood dust is generated as a by-product of machining. This paper discusses the granulometric analysis of selected samples of wood-settled dust from spruce (Picea abies L.), fir (Abies alba Mill.), oak (Quercus petraea Liebl.), beech (Fagus sylvatica L.), and alder (Alnus glutinosa L.). It also includes a sample of a mixture from timber production grinders in order to select the percentages of the various fractions (32 μm, 63 μm, 80 μm, 125 μm, 250 μm, 500 μm, 1000 μm, 2000 μm) of wood dust samples. Wood dust samples were made using a hand orbital sander and sized on an automatic mesh vibratory sieve machine. Comparison of the resulting granulometric fractions’ contributions to wood sanding dust was confirmed by the particle size. This paper presents selected characteristics of the chosen wood dusts by the size of particle dust fractions on the base of continual thermal loading. Thermal properties of wood dust samples were characterized by thermal gravimetric analysis (TGA). The TGA results indicated different thermal degradation fractions of the wood dust samples during thermal loading. The wood dust consisted mainly of fractions of 80 µm, 32 µm, and < 32 µm. These fractions of all wood dusts species presented more than 70.00% of the sample (alder dust has more 80% of sample). Thermal characteristics were not confirmed by the particle size and different wood dust.

Phenol-formaldehyde (PF) is a thermosetting resin that is widely used in many fields. One of its important applications is as an adhesive for wood-based panels manufacturing. In this research work, modified phenol-formaldehyde resins were prepared using hydroxymethylated alkaline rice straw lignin as a substitute for petroleum-based phenol in the range of 20 to 50% by weight. The molar ratios of sodium hydroxide to phenol-modified alkaline lignin and the formaldehyde to phenol-modified alkaline lignin were from 1.0 to 1.4, and 1.8 to 2.6, respectively. The parameters used to characterize the modified phenol-formaldehyde resins were: free-formaldehyde, gel time, viscosity, pH, and solid content. The structural differences and similarities between the prepared resins were determined by FTIR spectroscopy. Results obtained were discussed according to the requirements for adhesives utilization in plywood manufacture, and the optimum operating conditions were selected. Infrared spectra of lignin-based phenol formaldehyde (LPF) resins showed structural similarity with that of PF resin.

Quantitative aspects were investigated and compared for anatomical characteristics among compression wood (CW), lateral wood (LW), and opposite wood (OW) in the stem wood of Ginkgo biloba. Characteristics of each part were observed in the 5th, 10th, and 15th to 20th growth rings via optical and scanning electron microscopy. The crystalline characteristics were measured using an X-ray diffractometer. The microfibril angles (MFAs) were measured using the iodine method applied to the tangential section, as well as from the slopes of the pit apertures. The CW and OW showed similar tracheid lengths in the 5th and 10th growth rings; however, the CW was the shortest in the 15th to 20th growth rings. The CW showed the highest ray height and lowest ray number in each growth ring. The MFAs of the CW were greater than those in the LW and OW from both measurement methods. The MFAs obtained from the iodine method were smaller than that of the MFAs obtained from the pit aperture measurements. The CW had the lowest relative crystallinity in each growth ring, whereas the crystal width of the CW was the smallest in the 5th and 15th to 20th growth rings.

Multilayered wood composites were manufactured by introducing a cyclic pressing manufacturing method in which plies were added subsequently between each cycle as an alternative to the conventional single-cycle method based on a continual pressing of an entire set of veneers. The goal of the proposed cyclic method was to reduce the pressing time of multilayer wood-based composites. Scots pine veneers with two different moisture contents (5% and 10%) were selected. Heat transfer dynamics showed that the heat transfer through the veneers was remarkably dependent on the moisture content of the veneers, so the pressing time of the veneers with higher moisture content can be easily reduced. The density profile showed that by adding layer by layer, the density of the core is higher than that of the external layers. However, the mechanical tests of the composites produced by cyclic-pressing showed that the bending strength and modulus of elasticity, as well as the internal bond of composites were similar and in some cases even higher than composites pressed in a conventional way, while having pressing time reduced to less than a half.

Wood impregnated with styrene (ST) has a greater hydrophobicity than raw wood. Organically modified nanoclay can be used as a filler to increase the interfacial interaction between wood and ST. Raw wood shows an improved micro-structure, water uptake, modulus of rupture (MOR), modulus of elasticity (MOE), and thermal properties after impregnation with a mixture of i) non-branched organic ammonium-modified nanoclay (R-NH3+-clay) and ST; and ii) branched organic ammonium-modified nanoclay ((R)2N+(CH3)2-clay) and ST. Styrene with R-NH3+-clay-impregnated wood had a higher water uptake than the ST with (R)2N+(CH3)2-clay-impregnated wood. The MOE and MOR values of the ST with R-NH3+-clay-impregnated wood were higher than the ST with (R)2N+(CH3)2-clay-impregnated wood. Below 250 °C, the(R)2N+(CH3)2-clay with ST-impregnated wood had a greater thermal stability than the R-NH3+-clay with ST-impregnated wood.

In this research, 63 complete amino acid sequences of laccase enzymes from fungi (40), bacteria (5), insects (8), and plants (10) were used for a phylogenetic analysis. A common ancestor that diverged in the laccases in prokaryote and eukaryote was observed. Additionally, it was determined that there was a difference in the type of amino acids bound to the histidines linked to the copper atoms of the active site, and that a fungal laccase of approximately 279 Ma was an ancestor of the laccases in the basidiomycetes considered in this study. In contrast, Lacc 6 of Pleurotus ostreatus was used as a template to generate mutants. Through modeling, the changes in the secondary and tertiary structures of this enzyme were observed with the substitution of amino acids adjacent to histidines in the conserved region of the active site, via the presence of amino acids in a similar place in the laccases of bacteria.

Sodium carboxymethyl cellulose (CMC) has received a tremendous amount of attention because of its outstanding solubility in water. In this study, the deconstruction behavior of a fibrous CMC network in water was expressed with kinetic models. The experimental results suggested that the water adsorption process was the key factor in the deconstruction of a fibrous CMC network, and it was controlled by the physical adsorption, which was confirmed by the high correlation coefficient (R² > 0.95) of the pseudo-first-order kinetic model. The dissolving behavior of a fibrous CMC network in water was monitored with the focused beam reflectance measurement technique, which showed that the whole process included the network deconstruction and dissolution of the fibrous CMC itself. The CMC network dissolving process consisted of three periods: a deconstruction period (t₀ to t₁), deconstruction and partial dissolution period (t₁ to t₂), and partial dissolution period (after t₂). The first deconstruction period (t₀ to t₁) was the key period that controlled the dissolving efficiency of the water-soluble handsheets. The deconstruction period was 17 s for the CMC with a degree of substitution (DS) of 0.80, while it was 34 s for the CMC with a DS of 0.50.