Volume 15 Issue 1

The objective of this investigation was to elucidate the structural changes of the polysaccharides isolated by hydrothermal treatment of corn bran after twin-screw extrusion. The structures and antioxidant activities of the purified polysaccharides were investigated and compared by monosaccharide analysis, Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR). The results showed that the structures of the linkages and monosaccharide components of the purified polysaccharides were not affected strongly by the twin-screw extrusion pretreatment. However, the purified polysaccharides isolated from pretreated samples displayed significant differences in monosaccharide ratios, degree of branching/ linearity, and molecular weight. These physical changes may be related to the decrease of antioxidant activities of the polysaccharides. The present investigation contributes to the knowledge of how pretreatment by twin-screw extrusion affects the chemistry of corn bran polysaccharides. Results can be applied to improve the efficiency of hydrothermal extraction of polysaccharides from corn bran.

Selective Laser Sintering (SLS) technology can be utilized to recycle residues from forestry and agriculture, thereby alleviating shortages of materials and reducing energy consumption by producing wood-plastic pieces for industrial application. The mechanical strength of wood-plastic SLS parts is low, which restricts the application of this technology. In this study, a novel type of sisal fiber/poly-(ether sulfone) (PES) composite was prepared using a polymer mixing method in order to improve the mechanical properties of SLS parts. Single-layer sintering method was adopted to determine the proper processing parameters. The mechanical properties of the parts with different ingredient ratios and different particle sizes of sisal fiber before and after post-processing were tested using a universal testing machine. The morphology was examined using scanning electron microscopy (SEM). Results showed that the mechanical properties of the printed parts were relatively enhanced; when the mixing ratio of composite powder was 10/90 wt/wt. In addition, the part fabricated by powder of particles size less than 0.105 mm (0.125 mm ≥ PS < 0.105mm) had the best mechanical strength. Moreover, the post-wax treatment significantly improved the strength of the parts, and the surfaces became smoother.

Saccharomyces cerevisiae is one of the most promising unicellular fungi on account of its vital applications in biotechnology as well as bioethanol production. Improvement of ethanol production via very high-gravity (VHG) fermentation (fermentation at high sugar levels) was successfully developed using the ethidium bromide (EtB) mutagenesis of S. cerevisiae. This study found two developed mutants of S. cerevisiae (EtB20a and EtB20b) with varied capacity for ethanol production using EtB, depending on random amplified polymorphic DNA analysis. Mutant EtB20b showed improved ethanol yield (19.5%) compared with the wild-type (18.0%), while the other mutant EtB20a exhibited retarded ethanol production (9.1%). Optimization of ethanol production by mutant EtB20b was performed under other conditions including temperature, pH, inoculum size, and incubation period. The highest production capacity of the yeasts was 20.8, 19.9, 19.5, and 19.5% at an optimum temperature of 30 °C, pH 6.0, incubation period of 72 h, and 1 mL of yeast suspension (optical density at 600 nm) with glucose utilization of 42.6, 40.7, 39.8, and 39.9%, respectively.

Alkaline darkening has a negative effect on chemimechanical pulps produced from various eucalypt chips. For instance, the pulp’s brightness has been found to drop rapidly when alkali addition exceeds its optimum amount. Therefore, to compare the effects of different media on brightness gain, eucalypt mechanical pulps were bleached using a typical peroxide bleaching sequence in a water medium and in an ethanol-water (E/W) medium. Various pulp brightness levels and changes of residue chemicals in the spent bleaching liquors were investigated. Compared to water medium, the net brightness gain notably increased when using the E/W medium at the same chemical dosages. The rate of pulp brightness loss caused by increasing alkali dosage dropped in the E/W medium. Analyses based on ultraviolet-visible diffuse reflectance spectra of bleached pulps, as well as gel permeation chromatography and pyrolysis-gas chromatography-mass spectrometry spectra of the residues in the spent bleaching liquors, indicated that the contributions to brightness improvement from ethanol-water media could be explained by the selective dissolution and removal of phenolic- or guaiacyl-structured lignin fragments that result in the formation of chromophoric groups under alkaline conditions.

Biomass pyrolysis technology has important developmental prospects for biofuels and chemicals. Biochar as one of main pyrolysis products has excellent performance in soil improvement and adsorption of harmful elements. The environmentally persistent free radicals (EPFRs) in corn stalk powder and biochar obtained by pyrolysis at different temperatures were tested by electronic paramagnetic resonance spectrometry. After pyrolysis treatment, the biochar had a large number of stable free radicals. With increased pyrolysis temperature, the peak width of the free radicals signal in biochar decreased remarkably, and the widest peak of free radicals signal in biochar was presented at 450 °C, which was 0.69×10-4 T. The g-factor of free radicals in biochar decreased continuously as the temperature increased, while the peak height of free radicals first increased and then decreased. The peak height at 600 °C was only 23.8% of the peak height at 500 °C. The concentration of EPFRs in biochar increased with the increase of temperature from 450 °C to 500 °C, while it decreased at higher temperature (>500 °C). This phenomenon was similar to the trend of bio-oil collection efficiency. The experimental results showed a correlation between EPFRs of biochar and bio-oil yield at different pyrolysis temperatures.

The ink-absorption capacity is an important factor for evaluating the printing quality of paper. In this study, the effects of different parameters of papermaking on the ink-absorption capacity of paper were investigated. The results showed that hardwood pulp exhibited better performance in increasing the absorptivity of paper compared with softwood pulp. When the content of hardwood pulp in paper was increased from 0% to 100%, the ink mark length decreased from 5.1 cm to 4.3 cm. Furthermore, a basis weight change from 100 g/m2 to 60 g/m2 increased the ink-absorption capacity, as revealed by a decrease of the ink mark length from 4.8 cm to 4.4 cm. Both sizing agent and beating degree affected the ink-absorption performance of the paper. For example, a shorter ink mark length of 5.1 cm was obtained at a low beating degree of 5000 r compared with that of 5.1 cm at 15000 r.

Time-domain nuclear magnetic resonance (TD NMR) technology has been used for pore detection in porous materials for a long time, but there are few pore detection methods for microporous-mesoporous materials. The surface of different materials is obtained by pore detection of known pore materials. Relaxation rate, which obtains aperture information, has an important practical significance for the application of time-domain NMR technology in the characterization of porous materials. In this study, the T2 peaks of pores of known pore size materials, namely zeolite molecular sieves (0.3 nm and 1 nm) and anodized aluminum porous membranes (30 nm and 90 nm), were used to calculate the pore surface relaxation of zeolite molecular sieve with 0.3 nm pore size and 1 nm pore size. The ratio of the rate of the surface is 3.379; the ratio of the pore surface relaxation ratio of the 30 nm and 90 nm apertures of the anodized aluminum porous film is 3.031. This result is very close to the pore size ratio, indicating that the surface relaxation rate of the same material is directly related to the pore size, while the T2 peak can qualitatively measure the pore size.

The forest products industry is one of the most powerful industry branches of Turkey, and as in other developing countries, Turkey has a persistent trade deficit. The present paper aims to evaluate the forest industry products of Turkey regarding their economic contribution by Entropy-TOPSIS, which is a hybrid multicriteria decision making method. The evaluation was done to specify the products which will be able to create currency inflow most for reducing the trade deficit and help economic development. According to computations, the most contributing products are medium-density fiberboard (MDF), high-density fiberboard (HDF), industrial roundwood, and particle board. In addition, household and sanitary papers, as well as other paper and paper board products were found to have great economic potential.

To reveal the effects of vascular bundle and sheath-node tissues on mechanical strength, moso bamboo (Phyllostachys pubescens) was investigated via compression, bending, and tension tests. Quantitative analysis was applied on vascular bundle and sheath-node tissues using a mosaicking technique and Image-Pro Plus 6.0 software. Based on the analysis of internode and node specimens, it was found that 1) there was a significant difference between the tissues proportion and mechanical strength. A high tissues proportion resulted in a high compression strength, tension strength, and modulus of rupture, but a low modulus of elasticity. 2) There was no significant correlation between the tissues proportion and failure modes. 3) The presence of a bamboo node decreased the modulus of rupture, modulus of elasticity, and tension strength, but it did not affect the compression strength. 4) A bamboo node increased the likelihood of brash tension failure in the bending test and splintering tension failure in the tension test, but decreased the probability of splitting failure in the compression test. 5) The effects of bamboo node on strength were due to the irregular sheath-node and undifferentiated vascular bundles.

The charring properties and temperature profiles were studied for laminated bamboo exposed on one-side to ISO 834 fire. A linear model was adopted to represent the charring depth-time relationship. The average charring rate of laminated bamboo was around 1 mm/min, and the charring rate decreased as the total time increased. The temperature of the char front was approximately 270 °C, which was determined via analysis of the time-temperature curve. An additional mathematic model was developed to predict the temperature distribution in the uncharred zone under such conditions, and an abrupt change in temperature was witnessed near the char front. When compared to several different timber species found in previous literature and fire resistance standards, the charring rate of laminated bamboo was relatively high; therefore, future research should focus on way to strengthen the fire retardancy of laminated bamboo.