NC State
  • Editorialpp 5774-5777Turon, X., Venus, J., Arshadi, M., Koutinas, M., Lin, C. S. K., and Koutinas, A. (2014). "Food waste and byproduct valorization through bio-processing: Opportunities and challenges," BioRes. 9(4), 5774-5777.AbstractArticlePDF

    The bioeconomy era will rely on efficient fractionation of renewable resources via integrated biorefineries. The food supply chain waste, despite its inherent variability, could evolve into an important industrial feedstock on account of its availability, versatility, and sustainability, for the production of bio-based products. Waste streams generated from all stages of the life cycle of food products could be refined into different fractions, which will be either purified to high-value molecules or converted via green chemical and/or biotechnological routes for the production of bio-based products. A working group of the EUBis COST Action TD1203 is taking steps to gather a critical mass of knowledge and expertise to create innovation and technological breakthroughs.

  • Editorialpp 5778-5781Naylor, A. (2014). "Can wood be used as a bio-mechanical substitute for bone during evaluation of surgical machining tools?" BioRes. 9(4), 5778-5781.AbstractArticlePDF

    It is often not possible to machine human or animal tissue, such as bone, in a typical engineering workshop due to the numerous health risks associated. Further to this, currently used synthetic substitutes are also unsuitable for machining. This is mainly due to the aerosolization of harmful particles created during the machining process. It is however essential to thoroughly test and evaluate emerging orthopedic cutting tool designs, particularly when considering that osteonecrosis occurs at as low as 47 °C cutting temperature. It is proposed here that a composite bone model can be constructed using a dense hardwood to represent the hard cortical bone outer shell, and a less dense softwood to represent the spongy cancellous bone interior.

  • Editorialpp 5782-5783Hubbe, M. A. (2014). "Puzzling aspects of the hydrophobic sizing of paper and its inter-fiber bonding ability," BioRes. 9(4), 5782-5783.AbstractArticlePDF

    Internal sizing agents make it possible to prepare water-resistant paper from an aqueous suspension comprising water-loving fibers and an emulsified hydrophobic agent. Why doesn’t the hydrophobic treatment get in the way of inter-fiber bonding? The answer appears to involve the order in which nano-scale events happen during the manufacture of paper. It appears that the inter-fiber bonded areas develop first. Molecular distribution of the hydrophobic agents appears to happen later, especially during the later stages of evaporative drying. The topic seems to be crying out for someone to carry out appropriate experiments to shed more light on the mechanism.

  • Researchpp 5784-5793Kotlarewski, N. J., Ozarska, B., and Gusamo, B. K. (2014). "Thermal conductivity of Papua New Guinea balsa wood measured using the needle probe procedure," BioRes. 9(4), 5784-5793.AbstractArticlePDF

    A study was undertaken with the aim to determine thermal properties of balsa wood grown in plantations in Papua New Guinea. Thermal conductivity values were measured using the needle probe procedure according to ASTM D5334 (2008). The mean thermal conductivity results of balsa were in the range of 0.0381 W/mK to 0.0665 W/mK, similar to other materials currently used as insulators in the construction industry. A balsa sample with a density of 113 kg m3 had the lowest thermal conductivity value, 0.0339 W/mK, across the tangential and radial wood grain directions. Balsa is exported from Papua New Guinea mostly as end-grain panels to international markets to optimise its strength properties in the axial direction for applications that are exposed to compressive forces. This study revealed that there is the opportunity for Papua New Guinea balsa processors to consider producing perpendicular-grain panels for insulation markets, as the mean thermal conductivity values in this direction can be as low as 0.0381 W/mK, which is much lower than the thermal conductivity of the current end-grain panels at 0.0665 W/mK. The finding creates a potential design opportunity for balsa processors to consider entering new commercial markets to promote Papua New Guinea-grown balsa.

  • Researchpp 5794-5800Sun, F., Jiang, Z. Sun, Q., and Lu, F. (2014). "Changes in chemical composition and microstructure of bamboo after gamma ray irradiation," BioRes. 9(4), 5794-5800.AbstractArticlePDF

    Changes in bamboo composition and microstructure following 60Co gamma (γ) ray irradiation were investigated by solid state 13C cross-polarization (CP) magic-angle spinning (MAS) spectroscopic nuclear magnetic resonance spectrometry (NMR) and a field emission scanning electron microscope (FESEM). The results indicated that irradiation doses lower than 100 KGy resulted in the degradation of hemicelluloses via scission of molecular chains, but there was also repolymerization and condensation in lignin. Irradiation doses higher than 100 KGy resulted in the degradation of cellulose, hemicelluloses, and lignin by significant oxidation reaction and partial scission of biopolymer chains to yield more small fragments with carbonyl groups.

  • Researchpp 5801-5816Gupta, G., Sahai, V., and Gupta, R. K. (2014). "Thermal stability and thermodynamics of xylanase from Melanocarpus albomyces in presence of polyols and salts," BioRes. 9(4), 5801-5816.AbstractArticlePDF

    An extracellular xylanase from the thermophilic fungus Melanocarpus albomyces IIS 68 was evaluated for its activity and stability in the presence of polyols and salts at 60 °C, and found to be an effective protecting agent for thermal deactivation of enzyme. Response surface methodology was employed to study the synergistic effects of glycerol and NaCl (thermo-stabilizers) for xylanase stability. The addition of these thermo-stabilizers resulted in more than a 10-fold increment in enzyme half-life. Activation energy (Ea) and thermodynamic parameters such as ∆H, ∆G, and ∆S were calculated for the thermal inactivation of free and immobilized xylanase. The immobilized enzyme underwent substantially less conformational changes because of its enhanced stability and increased compactness, providing better thermo-stability at elevated temperatures. These findings suggest that the combined effect of glycerol and sodium chloride serves as a potential stabilizer for extracellular thermophilic xylanase, which finds commercial application in many industries, especially in the pulp and paper industry.

  • Researchpp 5817-5830Peng, Y., Liu, R., and Cao, J. (2014). "Effects of antioxidants on photodegradation of wood flour/polypropylene composites during artificial weathering," BioRes. 9(4), 5817-5830.AbstractArticlePDF

    The influence of antioxidants and of their compound systems were evaluated relative to the photodegradation of wood flour/polypropylene (WF/PP) composites using ultraviolet accelerated weathering. Six groups of samples were exposed in an accelerated weathering tester for a total duration of 960 h. The surface color, gloss, and flexural properties of the samples during weathering were tested. In addition, the weathered surfaces were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). The results revealed the following: (1) after weathering, all samples showed significant color fading and gloss change; (2) composites containing antioxidants showed less loss of flexural strength, fewer surface cracks, and better thermal stability after weathering than the control composite; (3) the crystallinity of polypropylene increased in weathered samples due to recrystallization of lower molecular weight polypropylene; and (4) antioxidant 168 (AO-168) was beneficial to color stability at the early stage of weathering, while composites containing 0.2% antioxidant 1010 (AO-1010) and 1.0% AO-168 (AO-1) maintained the highest retention ratios of flexural properties during weathering.

  • Researchpp 5831-5844Lou, B., Wu, S., Wang, X., Ma, K., and Li, M. (2014). "Experimentation and simulation of the combustion of biomass briquettes in southern China," BioRes. 9(4), 5831-5844.AbstractArticlePDF

    The thermogravimetry (TG) of typical biomass briquettes used as fuel in southern China was analysed to investigate the influences of fuel grain size and heating rate on combustion. The results suggested that grain size and heating rate exerted little influence on combustion. In accordance with the data and the TG results obtained from the fuel, a biomass grate incinerator process was numerically simulated using fluid dynamics-based incinerator code (FLIC) software to obtain the solid phase temperature distribution of the fuel along the bed length, the spatial temperature distribution of flue gas, and the underlying variation laws of the primary components. A comparison of the mass-loss curves from the numerical simulation to the TG analysis demonstrated that the two curves exhibited consistently staged variations, including dehydration and drying, fast pyrolysis and combustion of volatiles, and the burnout of residual carbon. The specific characteristics of the fuel obtained from these tests improved the accuracy of the numerical simulation, while the variations in temperature and components obtained were conducive to optimising the combustion process of a biomass incinerator.

  • Researchpp 5845-5857Teng, Y., Ding, J., Wang, B., Guo, X., and Cao, P. (2014). "Cutting forces and chip morphology in medium density fiberboard orthogonal cutting," BioRes. 9(4), 5845-5857.AbstractArticlePDF

    The influence of rake angle, cutting speed, and uncut chip thickness on cutting forces and chip morphology in medium density fiberboards orthogonal cutting was investigated. With regard to the normal cutting force and the feed force recorded, there were important variations when machining conditions were modified, or when some tool characteristics were changed. The findings led to the conclusion that there was a close relationship between the cutting conditions and chip formations as well as the cutting forces. Such forces were found to be particularly sensitive to changes in uncut chip thickness, as well as showing dependence on the cutting speed of the tools in orthogonal cutting.

  • Researchpp 5858-5870Li, H., Li, C., Chen, H., Zhang, D., Zhang, S., and Li, J. (2014). "Effects of hot-pressing parameters on shear strength of plywood bonded with modified soy protein adhesives," BioRes. 9(4), 5858-5870.AbstractArticlePDF

    The heating rate of the core layer of plywood during hot-pressing is of great importance to the final quality of the plywood and is affected by many factors, such as the hot-pressing temperature (THP), hot-pressing pressure (PHP), hot-pressing time (tHP), veneer layers, and moisture content. In this study, multi-plywood using modified soy protein (MSP) adhesives prepared to investigate the effects of THP, t HP, and veneer layers on the core layer temperature during hot-pressing. The results indicated that all the core layer temperature curves were divided into four stages. The first constant temperature stage and the slow warming stage were decisive with respect to the time needed for the core layer to reach the THP. The time of moisture vaporization was approximately 400 s in the 3-layer plywood and approximately 900 s in the 5-layer plywood. In order to get an ideal strength the tHP should greater than the time of moisture vaporization; therefore in theory, the optimum parameters of the 3-layer plywood production were tHP of 600 to 720 s and THP of 120 to 125 °C. The research provides a theoretical basis for optimizing the hot-pressing of plywood.