Volume 13 Issue 2

The effects and mechanism on the enzymatic hydrolysis of lignocellulose by metal ions were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), Fluorescence Spectra, and enzymatic kinetics and activity analyses of the enzymatic hydrolysis system. Fe3+ exerted the best enzymatic hydrolysis effect on pretreated wheat straw, and the highest reducing sugar conversion was 44.5%. SEM and FTIR indicated that alkali and ultrasonic pretreatments partially removed the lignin and hemicellulose from lignocellulose. DLS and fluorescence spectra results revealed that the electrostatic interaction between Fe3+ and the carboxyl group in the enzyme enlarged the enzyme’s steric structure. The data on enzymatic kinetics displayed that Fe3+ increased the maximum rate of reaction by 33.9% and the Michaelis-Menten by 5.72 g/L. The enzyme activity increase rate rose initially and then diminished, and the maximum increase rate was 36.1%.

The chemical composition and fuel properties of nine alternative jet fuels (named as AJF 1-9) and three commercial jet fuels (named as CJF 1, 2 and 3) are reported in this work. The fuels were characterized by GC/MS, SEP-GC/MS (for quantification of oxygenated molecules), viscosity, density, water content, water solubility at 0 °C, carbonyl content, total acid number, elemental composition, calorific value, flash point, differential scanning calorimetry, and surface tension. The content of n-paraffins, iso-paraffins, olefins, naphthenes, and aromatics are reported. The fuel rich in aromatics (AJF 1) has the highest density (0.90 g/mL), C content (over 90 wt. %), and water solubility, lowest calorific value, and high surface tension. The fuels with high contents of light molecules have the lowest flash points (AJFs 1, 6, and 8). AJF 2 is the most viscous fuel due to the presence of a single relatively heavy molecule. The content of oxygenated compounds measured was in all the cases very low and comparable with the amount found in commercial jet fuels. Overall, these fuels comply with most of ASTM requirements and offer opportunities to develop specialized products.

To achieve improvements in anti-mould properties, bamboo strips were subjected to extractions with different combinations of extraction media: boiling water, 1.0 wt.% hydrochloric acid (HCl), or 1.0 wt.% sodium hydroxide (NaOH). The impacts of different extraction methods on the structure and anti-mould properties of bamboo strips were investigated. The results suggested that bamboo strips treated alternatively with different extraction media were free of changes in crystalline structure and cell morphology but showed partial degradations of hemicellulose and decreases in the amount of free hydroxyl groups. As a result of these treatments, elimination or migration of extractives (including starch, soluble saccharides, and aliphatics) improved the resistance of bamboo strips to Penicillium citrinum, Trichoderma viride, Aspergillus niger, and a mixture of these mildews. Among the tested treatments, sequential extraction with boiling water, 1.0 wt.% NaOH, and 1.0 wt.% HCl resulted in a mildew-preventing efficiency of 96.9%, indicating optimum anti-mould properties.

A method was established for the determination of carboxyl groups in pulp by ultraviolet (UV) spectrophotometry. The method is based on the fact that the carboxylate pretreated with diluted hydrochloric acid was completely converted to carboxylic acid in pulp. In addition, content of carboxyl groups was measured with the capacity of copper ions exchanged with the hydrogen ions of carboxylic acid by UV spectrophotometry. The data showed that the pulp was suitable to react with 30% to 50% exchanged copper ions for 4 h at 45 °C. The results indicated that the method had excellent repeatability (RSD = 1.50%) and accuracy. Compared to traditional methods, the maximum relative error was less than 4%. The method is simple and accurate, such that it can be used for the efficient determination of carboxyl groups in pulp and other researches.

Distillers dried grains with solubles (DDGS) were employed as a bio-based resin/adhesive. DDGS were defatted with hexane, ball ground, and screened prior to use. DDGS flour was mixed dry with Paulownia wood (PW) to make composites using the following conditions: temperature of 150 to 195 °C, PW particle sizes of £ 75 to 1700 mm, pressure of 2.1 to 5.6 MPa, and using DDGS dosages of 10 to 100%. Molded composites were evaluated for their flexural properties. Composites were examined with Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction.  The best flexural properties were obtained from composites containing 50% DDGS and 50% PW, using 180 to 250 mm PW particles, pressed at 5.6 MPa, and employing 185 °C. Flexural properties of DDGS-PW composites were similar to composites fabricated using soybean flour (Prolia) as the resin/adhesive. Dimensional stability properties (water absorbance and thickness swelling) of DDGS-PW and Prolia-PW composites were similar. DDGS-PW composite properties satisfied several European Committee Industry Standards for fiberboards in terms of flexural properties but were inferior in terms of thickness swelling properties.

Effects of type of wood, number of blades, and depth and width of cutting were evaluated relative to the noise level during the machining of wooden materials in a spindle moulder. Lombardy poplar, Oriental beech, and medium density fibreboard (MDF) materials, at the thickness levels of 6 mm, 12 mm, 18 mm, 25 mm, or 30 mm, were planed for 20 min for each variable at the feed rate of 5 meters per min and at the cutting depth of 1 mm, 2 mm, or 3 mm with one or four blades. During machining of the samples, the noise levels were measured using a noise level meter. According to the data obtained, the highest noise level connected to the type of materials was measured in the machining of poplar wood, followed by that of beech wood and MDF. As the thicknesses of the materials were increased, increases up to 9 dBA of the noise level were measured. Moreover, machining the materials with one blade instead of four and with a cutting width of 1 mm instead of 3 mm increased the noise level by 2 dBA and 6 dBA, respectively.

The bending strength of hybrid wooden-core laminated timber (HWLT), a composite material made from existing cross-laminated timber (CLT) and plywood, was analyzed. Using plywood makes it possible to decrease the bending strength of the starting material. Korea Larch (Larix kaempferi Carr.) was used as plywood because of its popularity in Korea. To analyze HWLT’s bending properties, each component (lamina, plywood) was tested for bending, compression, and tensile strengths. The results showed that the HWLT’s bending strength depended on the plywood’s number of plies. With an increased number of plies, plywood’s bending strength decreased, and also HWLT’s bending strength decreased. Most of the failure showed in-plate shear failure of plywood. This result meant that use of reinforced plywood made it possible to increase HWLT’s bending strength for structural material.

Bark tannin extract from Acacia mearnsii (Mimosa ME) was modified at laboratory and pilot plant scales via the Mannich condensation reaction using formaldehyde and dimethylamine hydrochloride. Several conditions were varied during the modification procedure (heating rate, formaldehyde dosage, and Mannich solution activation time) to evaluate their influence on the shear viscosity and shelf life of the resulting products. It was possible to tune these properties with the reaction conditions. Modified condensed tannins with five distinct shear viscosities (30 cP to 430 cP) were selected to test the colour removal of anionic (Duasyn Direct Red and Acid Black 2) and cationic (Methylene Blue and Crystal Violet) dyes. The performance was monitored by ultraviolet spectroscopy. Colour removal was studied over different pH levels (1 to 14). Good decolouration results (85% to 96% reduction) were obtained with the simultaneous introduction of other additives to the process, which were bentonite and a cationic or anionic polyacrylamide, with minimal dosages of the latter additives. An improvement to decolouration performance with an increase in the biocoagulant viscosity was typically observed. However, for practical applications, modified condensed tannins with a lower viscosity may be preferred because they exhibited a longer shelf life and presented reasonable removal efficiencies.

Removing the epidermis of corn stalk rind can remarkably improve its bonding properties. This study aimed to determine the plate-making process by using intact corn stalk rind and thus utilize the crushed, removed epidermis. The thermal stability of corn stalk rind was investigated before and after removing the epidermis and gluing of the material using the hyphenated technique by simultaneous thermal analysis (STA), Fourier transform infrared spectroscopy (FT-IR), and gas chromatography-mass spectrometry (GC-MS). The results showed that the epidermis of corn stalk rind, from 90 °C to 200 °C, was conducive to softening the lignin in corn stalk rind and solidifying it as an adhesive. When the temperature was higher than 220 °C, the rate of weight loss rapidly increased and the thermal decomposition of hemicelluloses and cellulose in corn stalk rind after gluing was accelerated. The bonding process of corn stalk rind and adhesives is extremely complex, and intricate physical and chemical changes occur. Adhesive filled the surface cracks and depressions on the corn stalk rind, which not only improved its thermal stability, but also fixed corn stalk rind by forming connections.

The aim of this study was to identify the differences in the perception of the preferred level of corporate culture in Europe (Czech Republic and Slovak Republic), Asia (the People’s Republic of China (Beijing Municipality), and the Russian Federation (Sverdlovsk region). The research methodology was based on the Organizational Culture Assessment Instrument, which is a well-known and widely used measurement tool developed by Cameron and Quinn (1999). Based on statistical verification through an analysis of variance and Tukey’s honest significant difference (HSD) test, similarities in corporate cultures were seen for employees working in the Czech Republic, Slovak Republic, and People’s Republic of China, and there was a demand for a clan corporate culture. In the Russian Federation, employees preferred market and hierarchy corporate cultures. Furthermore, the corporate culture within the Baby Boomer, X, and Y generations was analysed. Within generations, major inter-regional differences were not confirmed. A positive corporate culture can contribute to further strategic development of companies and successful operation in the market.