Research Articles

Every year, millions of tonnes of dead biomass from algae and seagrasses are collected on the Mediterranean coasts. Posidonia oceanica is one of the most abundant species. In this work, leaves and rhizomes from this plant were pulped, alkalized, and cationized to make a value-added product. The main effects of five separate pulping variables, namely temperature, time, NaOH concentration, anthraquinone, and liquid-to-solid ratio were studied. The total procedure to produce cationic fibers took only 3 h (approximately), which made it a feasible process. A pseudo-second-order rate equation was used to fit the results of chemical modification via incorporation of quaternary ammonium ions. Characterization involved X-ray diffraction, scanning electron microscopy, and elemental analysis. The authors found that mild conditions were enough to achieve good results, reaching degrees of substitution of 0.20 for leaves and 0.12 for rhizomes.

In the biomedicine field, three-dimensional (3-D) printing of biomaterials can construct complex 3-D biological structures such as personalized implants, biodegradable tissue scaffolds, artificial organs, etc. Therefore, nanocellulose/gelatin composite hydrogels are often selected as bio-printing materials in the 3-D printing of biological scaffolds. Process parameters of 3-D printed bio-scaffolds were studied in this work because formation accuracy of scaffolds is an important part of the molding process. Firstly, the mixing proportion of nanocellulose and gelatin was explored, and the optimum proportion was selected. Then, the printing effects of different printing pressures, temperatures, speeds, and nozzle diameters were used in the 3-D printing. The filament widths were used to evaluate the molding effects. Finally, through the calculation and analysis of the grey correlation coefficient and grey correlation degree, the multi-objective optimization of the parameters was carried out. The combined effects of the process parameters and the influence degree order on the evaluation index were obtained. Using these parameters, the 3-D porous biological scaffolds were printed with high precision. Furthermore, using a microscope, the morphologies of CCK-8 cells were observed and the cell proliferation were analyzed. The results demonstrated that the printed bio-scaffolds had good biocompatibility.

The effects of cross-sectional geometry and force direction on bending strength (MOR) and modulus of elasticity (MOE) were investigated in selected softwoods. The specimens were constructed of Scots pine (Pinus sylvestris), Black pine (Pinus nigra), Siberian pine (Pinus sibirica), Stone pine (Pinus pinea), Nordmann fir (Abies nordmanniana), Oriental spruce (Picea orientalis), and Lebanon cedar (Cedrus libani). A total of 280 specimens were prepared from these seven species in two different cross-sectional geometries (circular and square, equal in area) and tested in two characteristic force directions (tangential and radial) by 10 replications. They were subjected to three-point bending tests according to TS 2474 (2005) and TS 2478 (2005) to obtain the MOR and MOE. The results showed that the type of cross-sectional area and direction of applied force, individually or together, had considerable effects on the MOR and MOE. The MOR values of the circular-sectioned specimens were 5% greater than those of the square-sectioned specimens. The MOE values of the circular-sectioned specimens were on average 19% greater than those of the square-sectioned specimens. The MOR and MOE values were on average 7% and 17% greater, respectively, for the force applied in the tangential direction.

The cutting power value, the surface quality of the machined surfaces, and the cutting edge wear were determined in the planar milling of oak wood (Quercus robur L.). The experimental tool was a milling head with two interchangeable blades. The basic material of the three milling cutters was HS 18-0-2-5 high-speed steel (ISO 4957 2018). Two milling blades were treated with different coatings: a multilayer AlTiCrN coating of thickness 1 μm to 4 μm (knife B) and a multilayer MoC coating of thickness 1 μm (knife C). Parameters for the experiment were as follows: tool angular geometry: α = 30°, β = 45°, γ = 15°, and δ = 75°; spindle speed: 3000 min-1, 4000 min-1, and 5000 min-1; feed rate: 6 m/min, 8 m/min, 10 m/min, 12 m/min, and 14 m/min; cutting depth: 1 mm and 2 mm. The results showed that the cutting power for face milling increased with milling length for all three blades. The greatest power was measured at milling using the knife C (mean value of 209.3 W). The wedge wear parameter WBW increased with milling length; knife C reached the greatest value (WBW = 54.0 μm at length of 270 m). The surface quality parameter (Ra) of the machined surfaces was almost unchanged with increasing milling length beyond 90 m for all knives.

This study analyzed how the quality class (A, B, C) of pine logs (Pinus sylvestris L.) from the Silesian Forestry Region influences the mechanical properties of timber produced from those logs. The study utilized 210 pieces of timber with nominal cross section dimensions of 40 × 138 mm that were 3500 mm long and made of logs from a specific quality class. From these timber pieces, the density (with the stereometric method), the dynamic modulus of elasticity (using the Mobile Timber Grader device), the global modulus of elasticity, and static bending strength (EN-408 2012) was determined. On the basis of the conducted analyses, the log quality class influenced the physical and mechanical parameters of structural timber to a limited degree. However, statistically significant differences were not found for the density, dynamic and global modulus of elasticity, and bending strength between timber elements made of logs from A and B quality classes (Anova analysis with significance level p < 0.05).

A superhydrophobic and flame-retardant filter paper was prepared by a simple immersion process intended for effective oil-water separation. Superhydrophobicity and flame retardancy were achieved via a magnesium hydroxide (Mg(OH)2) nanostructure formed on the filter paper surface and subsequent polydimethylsiloxane (PDMS) treatment. The surface chemical composition, phase structure, morphology, and wettability of the as-prepared paper were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and water contact angle (WCA) measurement. The as-prepared paper effectively separated both immiscible oil-water mixtures and oil-in-water emulsions while exhibiting good reusability and flame retardancy. Therefore, this study provided a simple method to prepare multifunctional filter paper, with promising potential applications in oily water treatment.

Recently, tree stumps have attracted attention as a source of woody biomass. This study investigated the practicability of brutian pine (Pinus brutia Ten.) root as an alternative raw material in the essential oil industry. The composition of volatile compounds of brutian pine root was investigated and compared with that of brutian pine stem wood. In the wood sample, the major volatile compound was α-pinene (32.69%) and in the root sample it was β-caryophyllene (25.41%). Terpenes (α-pinene, β-pinene, Δ3-carene, β-caryophyllene, and α-humulene) constituted the major compounds in the wood sample, whereas oxygen-containing components (linalool and (E)-anethole) were the main compounds in the root sample, in addition to terpenes (limonene, β-caryophyllene, and α-humulene). Monoterpenes, sesquiterpenes, terpene oxides, alcohols, aldehydes, ethers, esters, and ketones were identified as the main groups of volatile compounds in the wood and root samples of brutian pine. Except for monoterpenes, the amounts of the other main groups of volatile compounds were higher in the root sample than in the wood sample. The variation and number of detected volatile compounds indicate that the root of brutian pine might be a useful raw material for some industrial processes that use these volatile compounds in their production.

Lacquer wax represents a significant resource derived from the berries of Toxicodendron vernicifluum in China. The main chemical component of lacquer wax is fatty acid. The fatty acid isopropyl ester prepared from this acid has played a role in enhancing skin penetration and spreading properties, which makes it suitable for use as an important material in washing, cosmetics, and pharmaceuticals. In this study, the isopropyl ester of lacquer wax was synthesized by lipase-catalyzed transesterification for the first time ever. In addition, microemulsion of lacquer wax-based isopropyl ester (LW-IPE) was prepared by adding surfactant, co-surfactant, and water to solve the flocculation phenomenon of LW-IPE. The microemulsion was characterized by its stability, conductivity, viscosity, and particle size, which confirmed the formula of water-in-oil (W/O) microemulsion. The W/O microemulsion demonstrated an excellent thermodynamic stability in the temperature range between 20 °C and 40 °C and was stabilized with the addition of NaCl. In vitro evaluation of protection against ultraviolet light (UVA and UVB) demonstrated that arbutin in W/O microemulsion is capable to protect against UVA. This study is believed as providing valuable information on the performance of microemulsion systems suitable for use in the cosmetics and pharmaceuticals industries.

Cellulose nanocrystals (CNC) were successfully obtained from softwood pulp by p-toluenesulfonic acid (p-TsOH) hydrolysis under the treatment of p-TsOH mass concentration of 60%, temperature of 70 °C, reaction time of 4 h, and pulp to solution ratio of 1:20 (g / mL). Zeta potential and dynamic light scattering (DLS), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) were used to characterize the physical-chemical properties of the CNC. Under these conditions, the CNC exhibited good thermal stability in the suspension with a high crystallinity index of 90.1%. The CNC had an average diameter of 4.87 nm and average length 175.5 nm with no undesired elemental contamination. The degradation temperature of the CNC was relatively high at 310 °C. Moreover, p-TsOH was recovered by crystallization technology, and the recovery rate was over 70%, providing an environmentally friendly way for the development of biomass materials.

Rice straw pretreated with NaOH can be used to develop a kind of filling material of building walls for a greatly improved self-bonding property. In this work it was shown that NaOH solution can easily destroy the internal tubular structure, thus decreasing the stability of the rice straw. The mechanism explaining effects of the pretreatment measure was examined by analyzing the ash content using scanning electron microscopy (SEM). It was found that the ash content in the rice straw, elements like oxygen, carbon, silicon, can be reduced by the pretreatment of the rice straw with 1% (mass/mass) NaOH solution for 24 h. The thorny structures, spherical protuberance structures, and rod-shaped particles originally attached on the rice straws’ surface decreased by 90% after the treatment of NaOH solution. The contact area was correspondingly increased, and the wetting property on the surface was improved. As a result, the “bite force” among the pretreated rice straw surfaces was enhanced, leading to an improvement in self-bonding.