NC State
  • Editorialpp 1986-1987Chi, C., Zhang, S., Zhang, B., Wang, S., Wu, Y., and Gong, Y. (2015)."Professional graduate degree options in China: How to meet future needs for innovation and higher efficiency in the cellulose-based industries," BioRes. 10(2), 1986-1987.AbstractPDF
    The education system for professional graduate students is still incomplete in China nowadays, and this can lead to a lack of fit of their ability with the needs of modern enterprises and society. With the development of technology and the change of social needs, many traditional pulp and paper industries are being forced to transform. Thus, the cultivation of sophisticated versatile talents with preferable engineering and innovative ability is urgent in cellulose-based industries.
  • Researchpp 1988-1997Xu, Y., Sun, H., Li, X., Zhang, D., and Tian, Y. (2015). "Method of black liquor combustion to remove silicon from wheat straw pulping," BioRes. 10(2), 1988-1997.AbstractPDF
    The effects of aluminium sulphate and sodium aluminate on physical and chemical properties of wheat straw pulp black liquor were studied. Results showed that the expansion rate was enhanced by increasing the aluminum salt content; furthermore, the effect of sodium aluminate was better than that of aluminum sulfate. The maximum desilication rate of 92.31% was reached with the addition of 3% sodium aluminate. A rheometer showed that aluminum salt had little impact on the viscosity of thick black liquor, so even at a high temperature it could be conveyed by pumps in paper mill at 110 °C. The effect of aluminium salt on the silicon removal rate during black liquor combustion was also studied. The experimental results showed that both aluminium sulphate and sodium aluminate helped to remove silicon. The desilication rate of sodium aluminate reached 62.33%, higher than that of aluminum sulphate. SEM-EDX illustrated that the aluminum and silicon ions were formed into insoluble precipitates. It was optimal to use 3% sodium aluminate as desilication agent.
  • Researchpp 1998-2008Li, R., Ekevad, M., Guo, X., Cao, P., Wang, J., Chen, Q., and Xue, H. (2015). "Pressure, feed rate, abrasive mass flow rate influence on surface roughness for recombinant bamboo abrasive water jet cutting," BioRes. 10(2), 1998-2008.AbstractPDF
    The effects of pressure, feed rate, and abrasive mass flow rate on surface roughness were investigated during abrasive water cutting of recombinant bamboo. Two different thicknesses (10 mm and 15 mm) of recombinant bamboo were cut in the longitudinal and transversal directions by abrasive water jet. All experiments were arranged using response surface methodology. The parameter Rawas selected to represent the surface roughness. The value of Ra increased with an increase in feed rate and abrasive mass flow rate, but decreased with an increase in pressure. The surface roughness was lower when cutting the fiber longitudinally than when cutting transversally.
  • Researchpp 2009-2019Gaff, M., Gašparík, M., Borůvka, V., and Babiak, M. (2015). "Simulating stresses associated with the bending of wood using a finite element method," BioRes. 10(2), 2009-2019.AbstractPDF
    This article examines the stress-strain curves of various thicknesses of soft and hard wood when bent during three-point loading. The finite element method was used to simulate the course of stresses that occurred during the bending of these materials. Reference curves obtained by bending real specimens offered a basis for simulation. The results showed that with increasing material thickness, deflection values decreased and the proportionality limit increased; eventually, the bendability coefficient value decreased and the loading force necessary for bending increased. Moreover, it was apparent when bending hard materials that higher loading forces were necessary for different materials of the same thickness. It is possible to determine the stress-strain curves without having to perform experiments (except for indispensable reference ones) under real conditions.
  • Researchpp 2020-2031Huang, S., Wu, Q., Zhou, D., and Huang, R. (2015). "Thermal decomposition properties of materials from different parts of corn stalk," BioRes. 10(2), 2020-2031.AbstractPDF
    To help better utilize corn stalk (CS), pyrolysis behavior of materials from different parts of the CS including corn stalk without pith, corn root, and corn leaf were analyzed using thermogravimetric analysis (TGA) at heating rates of 5, 10, 20, and 25 °C/min. The apparent activation energies determined by the Friedman method for corn stalk without pith, corn root, and corn leaf were in the range of 26.4 to 103.6 kJ/mol, 37.6 to 69.5 kJ/mol, and 35.0 to 103.9 kJ/mol, respectively, depending on the conversion. The main thermal decomposition occurred within a temperature range of 200 to 350 °C (±10 °C). Most of the volatile materials decomposed at less than a 0.8 conversion rate. At greater than a 0.8 conversion rate, the remaining material was mainly char, and the decomposition of char proceeded at higher conversion rates. Different pyrolysis characteristics in the CS indicated that different treatments should be chosen according to different parts for achieving the optimum conversion rate in practical applications.
  • Researchpp 2032-2043Tavakkoli, A., Hemmasi, A. H., Talaeipour, M., Bazyar, B., and Tajdini, A. (2015). "Forecasting of particleboard consumption in Iran using univariate time series models," BioRes. 10(2), 2032-2043.AbstractPDF
    The performance of the Autoregressive Integrated Moving Average )ARIMA) model and Double and Holt-winters exponential smoothing techniques for forecasting the consumption of particleboard in Iran are compared. Annual time series data from 1978 to 2009 in the modeling process, and observations from 2010 to 2012 were used to check the accuracy of the models’ forecasting performance. Also, the models’ performances were calculated in terms of RMSE criterion, and the consumption of particleboard in Iran was forecasted up to the year 2017 using the most appropriate model. The results of comparing different forecast models showed that the ARMA (2,1) model yielded the lowest RMSE value compared to the other two models, which makes it more appropriate for the prediction of consumption of particleboard in Iran. Results also revealed that there might be an increasing trend in the consumption of particleboard, i.e., an average annual increasing rate calculated as 5% for particleboard. Thus, it was predicted that the consumption of particleboard would increase from 901,652 m3 in 2012 to 1,178,320 m3 in 2017.
  • Researchpp 2044-2056Awada, H., Elchinger, P. H., Faugeras, P. A., Zerrouki, C., Montplaisir, D., Brouillette, F., and Zerrouki, R. (2015). "Chemical modification of kraft cellulose fibres: Influence of pretreatment on paper properties," BioRes. 10(2), 2044-2056.AbstractPDF
    Chemical modifications of cellulose fibres (kraft pulp) in NaOH/H2O and NaCl/H2O systems were investigated. Handsheets were prepared that contained 25% of the modified fibres. Changes in the modified samples were examined by measuring their mechanical and optical properties and comparing them to those made with unmodified fibres. The observed differences were explained and supported by structural analyses, by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the NaOH/H2O pretreatment led to a significant deterioration of optical and strength properties of the handsheets. These modifications affected both the inner part of the crystalline cellulose (change from cellulose I to cellulose II) and the morphology of the fibers. Conversely, these properties slightly improved after propargylation, due to the propargyl functional groups. For the NaCl/H2O system, a significant enhancement of the mechanical properties of the handsheets was noted, such as an increase of up to 108% of the tear index. The propargylation further increased the tear index (by 157%). These enhancements were not accompanied by significant changes at both the micrometric and nanometric scales, except for the increase of the crystallinity index after propargylation.
  • Researchpp 2057-2066Zborowska, M., Stachowiak-Wencek, A., Nowaczyk-Organista, M., Waliszewska, B., and Prądzyński, W. (2015). "Analysis of photodegradation process of Pinus sylvestris L. wood after treatment with acid and alkaline buffers and light irradiation," BioRes. 10(2), 2057-2066.AbstractPDF
    The purpose of this investigation was to evaluate the effect of acid and alkaline treatment of pine wood on photodegradation. The work presented here deals with changes in the wood colour and infrared spectrum caused by UV light. The colour changes were monitored with a reflectance spectrophotometer. The analysis of the colour changes in wood surfaces was carried out by measuring CIE L*a*b* parameters. Infrared spectroscopy was used to study chemical changes occurring on the surface of wood samples caused by light. Wood treated with alkaline buffer was characterized by higher brightness changes than wood treated with acid. The surface of samples treated with alkaline buffer revealed similar resistance to photodegradation against both outdoor and indoor light. Greater changes in colour were detected in the case of samples treated with acid and exposed to outdoor light in comparison to indoor light. FTIR results showed degradation in the lignin structure both in the case of samples treated with acid and alkaline buffer and exposure to outdoor and indoor irradiation. The difference between the samples treated with UV 340 nm and UV 351 nm irradiation was seen in the 1512 cm-1 band.
  • Researchpp 2067-2082Emeko, H. A., Olugbogi, A. O., and Betiku, E. (2015). "Appraisal of artificial neural network and response surface methodology in modeling and process variable optimization of oxalic acid production from cashew apple juice: A case of surface fermentation," BioRes. 10(2), 2067-2082.AbstractPDF
    This study assessed the effects and interactions of cashew apple juice (CAJ) concentration, pH, time, methanol concentration, and NaNO3 concentration on oxalic acid fermentation in a central composite design. The efficacies of artificial neural network (ANN) and response surface methodology (RSM) in modeling and optimizing the process were evaluated using correlation coefficient (R), coefficient of determination (R2), and absolute average deviation (AAD). The highest oxalic acid production observed was 120.66 g/L under optimum values of a CAJ concentration of 291 g/L, pH of 6.9, time of 10.82 days, methanol concentration of 2.91% (v/v), and NaNO3 concentration of 1.05 g/L that were numerically predicted by the developed RSM quadratic model. Using the developed ANN model coupled with rotation inherit optimization, the highest oxalic acid production observed was 286.75 g/L under the following optimum values: CAJ of 291 g/L, pH of 6.5, time of 12.64 days, methanol concentration of 3.82% (v/v), and NaNO3 concentration of 2.41 g/L. The results showed that the ANN model (R = 0.9996, R2 = 0.9999, AAD = 0.21%) was better than the RSM model (R = 0.9986, R2 = 0.9973, AAD = 1.00%) for optimizing oxalic acid fermentation. The use of the ANN model led to a 2.4-fold increase in oxalic acid yield over the RSM model.
  • Researchpp 2083-2093Aytin, A., Korkut, S., Ünsal, Ö., and Çakıcıer, N. (2015). "The effects of heat treatment with the ThermoWood® method on the equilibrium moisture content and dimensional stability of wild cherry wood," BioRes. 10(2), 2083-2093.AbstractPDF
    Low hygroscopicity is an important factor favoring the use of heat-treated wood materials. Hence, wild cherry (Cerasus avium (L.) Moench) wood was subjected to heat treatment with the ThermoWood® method for about 1 and 2 hours at temperatures of 190 and 212 °C in an industrial business. Then, trial samples were prepared and divided into two groups. By being conditioned in the environments of 20 °C and 65% relative humidity (WC1), 20 °C and 85% relative humidity (WC2), 20 °C and 30% relative humidity (WC3), and 23 °C and 50% relative humidity (WC4), equilibrium moisture content (EMC) and dimensional stability (DS) values of the samples in the first group were determined. The water thickness swelling (WTS) and water retention (WR) features of the samples of the second group were examined by keeping them in water both 24 and 72 h. The results show that EMC and WTS decreased with increasing treatment temperature and durations. Also, DS was improved. On the other hand, the WR values of all the samples stayed approximately the same.
  • Researchpp 2094-2102Lukmandaru, G. (2015). "Chemical characteristics of teak wood attacked by Neotermes tectonae," BioRes. 10(2), 2094-2102.AbstractPDF
    The teak trees in certain areas of Java Island are frequently attacked by Neotermes tectonae termites. Trees attacked by this species have a tumor-like growth in the stem that can be easily identified in the field. This study evaluated the chemical properties of the attacked wood. Based on a visual inspection, the type of attacks were classified as either type I, if included phloem was formed in the heartwood, or type II, which was distinguished by the softened and hollowed areas in the heartwood. For each type, three trees were cut along with a healthy tree for comparison. Comparison among type I, type II, and normal tree tissues showed huge differences in hemicellulose and extractive contents, composition of ethanol-toluene soluble extracts, ash/acid insoluble ash contents, and pH values. Comparing the two types of abnormalities along the radial direction, significant differences were observed in the cellulose contents. The lowest values of both sugars were obtained in the soft part of type II. Further, the levels of ethanol-toluene soluble extracts and their fractions (mainly low-polarity fractions) were affected by the radial direction. No significant differences in radial direction were found in the inorganic materials levels or in pH values.
  • Researchpp 2103-2112Choudhary, S. J., Mehmood, S., Naz, H., Jaafar, H. Z. E., and Zia-Ul-Haq, M. (2015). "Effect of sulfuric acid on pretreatment of YSS-10R variety of sorghum and analysis of its interaction with temperature and time," BioRes. 10(2), 2103-2112.AbstractPDF
    Considering the possible threats to the oil supply due to the rapid depletion of oil reservoirs and the negative environmental impacts of petroleum use, developing an environmentally friendly biofuel such as bioethanol is needed. Pretreatment is a critical step in the production of lignocellulosic bioethanol. In this study, the effect of sulfuric acid on the pretreatment of the YSS-10R variety of sorghum was evaluated. Response Surface Methodology (RSM) was employed to develop an experimental design matrix and evaluate the effect of pretreatment parameters on the release of fermentable sugars. Sorghum straw was treated with sulfuric acid concentrations of 0.5, 1.75, and 3% (V/V) at temperatures of 70, 100, and 130 °C for reaction times of 10, 20, and 30 min. The maximum glucose yield was 7.66 g/L (0.064 g/g) and was obtained via pretreatment with 0.5% H2SO4 at 100 °C for 10 min. That of xylose was 7.62 g/L (0.064 g/g), obtained via pretreatment with 0.50% H2SO4 at 130 °C for 20 min. The pretreatment conditions for maximum xylose yield were determined to be 2% H2SO4, 130 °C, and 20 min. Results indicate that sulfuric acid is an efficient catalyst for pretreatment at high temperatures and relatively long reaction times.
  • Researchpp 2113-2129Malakani, M., Bazyar, B., Talaiepour, M., Hemmasi, A. H., and Ghasemi, I. (2015). "Effect of acetylation of wood flour and MAPP content during compounding on physical properties, decay resistance, contact angle, and morphology of polypropylene/wood flour composites," BioRes. 10(2), 2113-2129.AbstractPDF
    The effects of acetylation of wood flour with vinylacetate and the content of Maleic Anhydride Polypropylene (MAPP) coupling agent before compounding were evaluated relative to water absorption and thickness swelling. Hot water was used to extract materials of sawdust fir flour before acetylation. Fir flour was successfully acetylated using vinylacetate (VA) in the presence of potassium carbonate. The modification was confirmed by the weight percent gain (18.8%) and Fourier transform Infrared (FTIR) spectroscopy. The acetylated or control wood flour was mixed with MAPP coupling agent (0, 3, & 6 wt%) at 60 rpm and 160 °C, followed by extrusion. The wood plastic composite (WPC) was made by hot pressing at 200 °C and 25 MPa for 5 min. Specimens were exposed to white-rot decay for 16 weeks. In addition to the weight loss due to fungal treatment, water absorption, thickness swelling, and contact angle of the acetylated and decayed samples was investigated. Increasing the percentage of MAPP was found to decrease the percentage of weight loss, water absorption, and thickness swelling in all of the samples. In contrast, increasing the MAPP percentage increased the contact angle in all samples. The SEM micrographs revealed that the bonding between fibers and polymeric material was improved and strengthened by MAPP addition.
  • Researchpp 2130-2142Yang, X., Li, S., Xia, J., Song, J., Huang, K., and Li, M. (2015). "Renewable myrcene-based UV-curable monomer and its copolymers with acrylated epoxidized soybean oil: Design, preparation, and characterization," BioRes. 10(2), 2130-2142.AbstractPDF
    An innovative myrcene-based ultraviolet curable vinyl ester monomer was synthesized, and its molecular structure was analyzed with Fourier transform infrared spectroscopy and nuclear magnetic resonance (1HNMR and 13CNMR) analysis. A series of copolymers were also prepared by mixing the myrcene-derived monomer with another vinyl ester monomer, acrylated epoxidized soybean oil, under ultraviolet light. The curing process was monitored using Fourier transform infrared spectroscopy. Ultraviolet curing analysis showed that all the mixed systems had high curing rates and were fully cured within the first 30 seconds. When the weight ratio of myrcene-derived monomer to acrylated epoxidized soybean oil was 50/50, the ultimate double bond conversion reached 94.08%. Dynamic mechanical analysis showed that the storage modulus and glass transition temperature of the cured resins both increased with increasing content of myrcene vinyl ester monomer because the molecular structure of myrcene-derived vinyl ester monomer was more rigid and stronger than that of acrylated epoxidized soybean oil. Thermogravimetric analysis indicated that the main thermal initial decomposition temperatures were all above 360 °C, demonstrating that the copolymers had modest thermal stability.
  • Researchpp 2143-2155Obradovic, J., Fardim, P., Lassila, L., Navard, P., and Kronlund, D. (2015). "High-pressure treatment of DMAc/LiCl swollen softwood pulp," BioRes. 10(2), 2143-2155.AbstractPDF
    Swollen softwood cellulose pulp in a DMAc/LiCl solvent system was compressed under elevated pressure (up to 900 MPa) in a Bridgman anvil press. The influence of high pressure on two cellulose systems was studied by measuring X-ray diffraction, mechanical and optical properties and observing scanning electron micrographs of the morphology. Compressed swollen cellulose, washed with distilled water, had lower elastic modulus and hardness compared to swollen cellulose washed with a combination of 2-propanol and deionized water. This work showed that material with lower mechanical properties will be affected more by compression and will result in higher mechanical properties after pressure treatment. Transmitted light in the visible range for both systems was increased after elevated pressure was applied. The XRD measurements revealed the decrease of the cellulose crystallinity after high pressure treatment for all swollen cellulose samples. The morphology of the compacted samples showed noticeable differences between the compact smooth surface and the layered core.
  • Researchpp 2156-2166Reixach, R., Puig, J., Méndez, J. A., Gironès, J., Espinach, F. X., Arbat, G., and Mutjé, P. (2015). "Orange wood fiber reinforced polypropylene composites: Thermal properties," BioRes. 10(2), 2156-2166.AbstractPDF
    A major drawback of natural-based composites is the incorporation of reinforcements that are less thermally stable than the matrix; therefore, the thermal properties of the resultant composite material needs to be studied. In this work, orange wood fibers were used to reinforce polypropylene. The effects on the thermal properties of the polymeric matrix were analyzed. To this end, differential scanning calorimetry (DSC), thermogravimetry (TGA), thermomechanical analysis (TMA), and dynamic-mechanical analysis (DMA) were performed. It was found that the degradation of the material took place in two distinct phases: the reinforcement, close to 250 °C, and the matrix, above 340 °C. DSC results showed that fiber reinforcement did not influence the transition temperatures of the materials, although it did affect the polymer crystallinity value, increasing by 7% when the composite is reinforced with 50% of the lignocellulosic reinforcement. The coefficient of expansion obtained by TMA indicated that thermal expansion decreased as the amount of reinforcement increased. DMA assays showed that the reinforcement did not modify the glass transition (20 to 25 °C) temperature and confirmed that the addition of reinforcement increased the crystallinity of the product.
  • Researchpp 2167-2176Yu, X., Zhu, X., Gu, Z., and Lai, S. (2015). "Antioxidant activity in vivo and in vitro of two feruloyl oligosaccharides preparations produced from wheat bran and fermented by Aureobasidium pullulans," BioRes. 10(2), 2167-2176.AbstractPDF
    The antioxidant functions of two feruloyl oligosaccharide (FO1 and FO2) were investigated in vivo and in vitro. Effects of FO1 and FO2 on hemolysis of rat red blood cell (RBC) and malondialdehyde (MDA) formation in rat liver homogenate and rat liver mitochondria in vitro were studied. Hemolysis of rat RBC and MDA formation in rat liver homogenate and rat liver mitochondria were inhibited in a dosage-dependent manner by FO1 and FO2 in the tested concentration range of 0.5 to 10 mg/mL. The results showed that FO1 and FO2 had antioxidative activity in vitro, and the effect of FO2 was better than that of FO1. With increasing dosage, FO1 and FO2 could increase the activity of SOD and GSH-Px in serum of S180 tumor-bearing mice, reduce the level of MDA, and thus improve the activity of the antioxidant in vivo. When the dosage reached 250 mg/kg/d, FO2 was more likely to improve the capabilities of the antioxidants of tumor-burdened mice than were 5-FU and FO1 in vivo.Thus, these oligosaccharides may be used as functional biological materials produced from fermented lignocellulose of WB.
  • Researchpp 2177-2184Ji, X., Liu, S., Wang, Q., Yang, G., Chen, J., and Fang, G. (2015). "Wet oxidation pretreatment of wood pulp waste for enhancing enzymatic saccharification," BioRes. 10(2), 2177-2184.AbstractPDF
    Effective pretreatment of wood pulp waste is important for enhancing enzymatic saccharification. For this reason, wet oxidation process conditions were considered with the hypothesis that the alkaline oxygen conditions would favor delignification and hydrolysis of lignocellulose. Enzymatic saccharification was greatly improved to 42.9% in terms of reducing sugar yield under the conditions of pH = 10, oxygen pressure = 1.2 MPa, time = 15 min, and temperature = 195 °C. A total of 39% of lignin and 73% of hemicellulose were removed and dissolved into the hydrolyzate. Furthermore, the chemical structure, crystallinity, and morphology of the treated substrate were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM).
  • Researchpp 2185-2194Qin, J., Qin, Z., Yin, X., Zeng, Q., and Zhu, L. (2015). "Synthesis and characterization of alkylated bacterial cellulose in an ionic liquid," BioRes. 10(2), 2185-2194.AbstractPDF
    Bacterial cellulose was alkylated by alkyl halide in the ionic liquid 1-butyl-3-methylimmidazolium chloride ([Bmim]Cl) with NaH as the alkaline agent. The derivatives were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analyses, X-ray diffraction, and thermal gravimetric analyses. The resultant bacterial cellulose alkylated derivatives (BCADs) had a degree of substitution (DS) between 0.21 and 2.01. The effects of the alkylating agent, reactant amount, and temperature on the DS were investigated. BCADs with a butyl substituent had a higher DS than did those with ethyl or propyl groups. The crystallinity and thermal stability of the derivatives decreased after modification owing to the change in morphological structure.
  • Researchpp 2195-2212Antes, R., and Joutsimo, O. P. (2015). "Effects of modified cooking on fiber wall structure of E. globulus and E. nitens," BioRes. 10(2), 2195-2212.AbstractPDF
    This work examined the impact of SuperBatch™ (SB), CompactCooking™ (CC), and Lo-Solids™ (LS) modified kraft pulping on the fiber wall structure of unbleached and bleached unrefined pulps of E. globulus and E. nitens. The kappa number target for all pulps was 17 ± 0.5. It was found that E. nitens had higher water retention values (WRVs) and fiber saturation point (FSP) for both bleached and unbleached pulps versus E. globulus. Fibril lateral aggregates width of unbleached pulps increased as WRV increased. After bleaching there was an inverse trend in correlation of WRV versus the lateral fibril aggregate width. The modified cooking methods or wood species did not have an influence on lateral fibril aggregate width. The higher WRV and FSP values for E. nitens were not reflected in the cumulative pore volume measurements including pore widths below 216 nm.
  • Researchpp 2213-2222Chen, Q., Guo, X., Ji, F., Wang, J., Wang, J., and Cao, P. (2015). "Effects of decorative veneer and structure on the thermal conductivity of engineered wood flooring," BioRes. 10(2), 2213-2222.AbstractPDF
    This paper explores the thermal conductivity of engineered wood flooring, which is widely used in world market. The effects of decorative veneer type and structure on the thermal conductivity of engineered wood flooring were studied. Four decorative veneer types and three different structures of engineered wood flooring served as test specimens. All samples were placed in a laboratory simulating a heating system environment, of which the temperature should be measured three times every five minutes. The temperature differences between the upper and lower surfaces were as follows: cherry > maple > birch > eastern black walnut. Three types of structures also showed differences in temperature changes, based on five-minute observations. The larger the decorative veneer’s density, the higher the thermal conductivity, and the faster the heat transferred, meaning less heat was lost. The thermal conductivity of three-layer engineered wood flooring, with decorative veneer made of sawn wood, exhibited the best properties. The second best of the three samples was the three-layer engineered wood flooring with decorative veneer made of thick veneer and plywood. Finally, a multilayered engineered wood flooring performed the worst. The engineered wood flooring for use in heating systems should be chosen for its larger density of decorative veneer made of sawn wood.
  • Researchpp 2223-2234Zhao, S., Xu, G., Chang, J., Chang, C., Bai, J., Fang, S., and Liu, Z. (2015). "Direct production of levulinate from carbohydrates catalyzed by H-ZSM-5 supported phosphotungstic acid," BioRes. 10(2), 2223-2234.AbstractPDF
    A series of supported phosphotungstic acid (H3PW12O40, HPW) catalysts, including HPW/β, HPW/Sn-β, HPW/H-Y, HPW/H-ZSM-5, HPW/USY, HPW/ReUSY, and HPW/SBA-15, were prepared using an impregnation method foralcoholysis of fructose to ethyl levulinate in ethanol. Among these catalysts, HPW/H-ZSM-5 showed the highest catalytic activity, and the yield of ethyl levulinate from fructose increased with increasing phosphotungstic acid loading. The yield of ethyl levulinate reached 43.1% at 160 °C for 2 h over 20 wt.% HPW/H-ZSM-5, and the solid catalyst could be reused at least three times. EL yields of 19.1%, 27.3%, 37.4%, and 8.7% could be obtained from glucose, sucrose, inulin, and cellulose, respectively. Furthermore, the catalysts were characterized by BET surface area, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. HPW/H-ZSM-5 showed good catalytic activity for the direct production of ethyl levulinate from fructose.
  • Researchpp 2235-2243Leminen, V., Tanninen, P., Lindell, H., Varis, J. (2015). "Effect of blank holding force on the gas tightness of paperboard trays manufactured by the press forming process," BioRes. 10(2), 2235-2243.AbstractPDF
    Although several authors have studied 3D forming using the press forming process, the gas tightness of polymer-coated paperboard trays has not been widely researched. In this paper, the effect of blank holding force on the surface quality and tightness of press-formed paperboard trays was researched. The press-formed trays were heat-sealed with a multilayer polymer lid. The tightness of the trays was analyzed by following the oxygen content of the packages over the course of 14 d and by using a penetrant coloring solution to locate possible leaks. The results indicate that the blank holding force had a great effect on the quality and tightness of the trays, especially in the case of a rectangular geometry. The geometry of the formed trays played a significant role in process parameter selection, and more demanding geometries emphasize the importance of parameter optimization. However, with the correctly selected parameters, the use of modified atmospheric packaging (MAP) in polymer coated paperboard trays was shown to be possible. The oxygen content of both analyzed geometries was found to be less than 1% 14 d after sealing. It was also demonstrated that the gas tightness of a seal cannot be confirmed using a penetrant solution test exclusively.
  • Researchpp 2244-2255Gan, S., Mohammad Padzil, F. N., Zakaria, S., Chia, C. H., Syed Jaafar, S. N., Chen, R. S. (2015). "Synthesis of liquid hot water cotton linter to prepare cellulose membrane using NaOH/urea or LiOH/urea," BioRes. 10(2), 2244-2255.AbstractPDF
    The liquid hot water (LHW) pretreatment on cotton linter (CL) was carried out using an autoclave heated in a hot oil bath. The LHW pretreated CL (LCL) was dissolved in NaOH/urea and LiOH/urea aqueous solutions and subsequently used to produce cellulose membrane. The effects of LHW pretreatment, amount of cellulose, and type of alkaline solvent on properties of cellulose solution and cellulose membrane were studied. The formation of cellulose II and crystallinity index (CrI) on the cellulose membranes were confirmed by X-ray diffraction (XRD). The morphology of cellulose membranes were observed by field emission scanning electron microscopy (FESEM). The LHW pretreatment resulted in higher cellulose solubility, higher cellulose solution viscosity, and improved properties of regenerated cellulose products compared to non-treated cellulose. Results also revealed that the amount of cellulose used affected the solubility and viscosity of the cellulose solution and the higher dissolving power of the LiOH/urea system as compared to the NaOH/urea system. In fact, higher solubility and viscosity properties are key factors in many cellulose applications such as membranes, fibers, hydrogels, and other regenerated cellulose products.
  • Researchpp 2256-2265Íñiguez-González, G., Montón, J., Arriaga, F., Segués, E. (2015). "In-situ assessment of structural timber density using non-destructive and semi-destructive testing," BioRes. 10(2), 2256-2265.AbstractPDF
    Both non-destructive and semi-destructive tests can potentially be very efficient methods for the assessment of structural timber density. This paper describes an investigation into the suitability of three techniques: core drilling, probing, and screw withdrawal. It presents the results after testing 150 pieces of large cross-section (80 mm x 120 mm) structural timber of radiata pine (Pinus radiata D. Don.) from a Spanish source. A strong correlation was found between specimen density and core drilling. Meanwhile, there was also a meaningful correlation with the screw withdrawal, and an acceptable correlation with probing. Even though differences were observed in their predictive capacity, none of these procedures should be rejected as a way of estimating density, as each has its own respective advantages and limitations.
  • Researchpp 2266-2280Liu, Z., Cao, Y., Wang, Z., Ren, H., Amidon, T. E., and Lai, Y. (2015). "The utilization of soybean straw. I. Fiber morphology and chemical characteristics," BioRes. 10(2), 2266-2280.AbstractPDF
    Various soybean straw (stem and pod) samples were dissolved in 8% lithium chloride/dimethyl sulfoxide (LiCl/DMSO) following 4 h of planetary ball-milling. The solubility, extractable lignin yield, and crystal structure of the ball-milled soybean straw were greatly affected by the ball-milling pretreatment. The dissolved soybean straw could be regenerated by being poured into excess distilled water under rapid stirring. The total regenerated fraction yield decreased with the increase in the duration of ball-milling. Approximately 10% to 25% of the straw mass was lost in the dissolution-regeneration procedure. For comparison, ethylenediamine (EDA)-pretreated soybean straw was also completely dissolved in 8% LiCl/DMSO to form a homogeneous solution containing 1% straw after 24 h of continuous stirring. The dissolution-regeneration performance of soybean straw submitted to the EDA pretreatment was quite different due to the lack of vigorous ball-milling.
  • Researchpp 2281-2288Li, X., Du, G., Wang, S., and Meng, Y. (2015). "Influence of gender on the mechanical and physical properties of hemp shiv fiber cell wall in dioecious hemp plant," BioRes. 10(2), 2281-2288.AbstractPDF
    Hemp (Cannabis sativa L.) shiv has great potential for the production of bio-composites as a reinforcement material. To gain more information about hemp shiv, this research studied the influence of gender on the physical and mechanical properties of the fiber cell wall in the shiv of three dioecious hemp plant varieties by optical microscopy, image analysis software, WXRD, and nanoindentation. The results show that a hemp plant’s gender greatly influences the properties of hemp shiv. While long and thin in female hemp shiv, the fibers are shorter with a larger diameter in male hemp shiv. In addition, the cell walls in female shiv are thinner than those in male shiv. The microfibril angle (MFA), relative degree of crystallinity, elastic modulus, and hardness values of fiber cell walls as well as the lignin content in male hemp plants are higher than those in female hemp plants. Besides, the relationship between mechanical properties and MFA do not align with those observed in previous research, which shows that the gender of an individual plant has a greater effect on the mechanical properties of the fiber cell wall than does its MFA. Thus, when the fiber from this dioecious plant is investigated or used, the sex of the plant should be known and considered.
  • Researchpp 2289-2304García-Fuentevilla, L. L., Martin-Sampedro, R., Carbajo, J. M., Diaz, M. J., and Eugenio, M. E. (2015). "Enhancement of TCF and ECF bleaching processess by urea and enzymatic pretreatments: Optimization of a laccase-mediator pretreatment," BioRes. 10(2), 2289-2304.AbstractPDF
    A TCF bleaching sequence consisting of a urea pretreatment stage (U), laccase-mediator system stage (L), alkaline extraction stage (E), and hydrogen peroxide bleaching stage (P) was used to study the effect of five independent variables on the dependent variables pulp properties, hydrogen peroxide consumption, and residual enzyme activity. Results showed that the most influential variable was L stage pulp consistency, followed by mediator and laccase dosages. On the other hand, oxygen pressure did not have a significant effect. The optimal UL partial sequence significantly enhanced the EP bleaching sequence: 49.8% vs. 33.4% delignification, up to 65.6% ISO vs. 56.3% ISO bleached brightness, and 50.3% vs. 89.9% peroxide consumption in the P stage. The ULE partial sequence also improved an ECF bleaching sequence (ULED0E1D1): 0.6 vs. 1.0 final kappa number; 82.7% ISO vs. 76.0% ISO brightness; and 54.1 N∙m∙g-1 vs. 51.9 N∙m∙g-1 and 3.3 KPa∙m2∙g-1 vs. 2.7 KPa∙m2∙g-1, tensile and burst indexes, respectively, when compared to the control D0E1D1 sequence.
  • Researchpp 2305-2317Liu, Z., Cao, Y., Wang, Z., Ren, H., Amidon, T. E., and Lai, Y. (2015). "The utilization of soybean straw. II. Dissolution & regeneration of soybean straw in LiCL/DMSO," BioRes. 10(2), 2305-2317.AbstractPDF
    Various soybean straw (stem and pod) samples were dissolved in 8% lithium chloride/dimethyl sulfoxide (LiCl/DMSO) following 4 h of planetary ball-milling. The solubility, extractable lignin yield, and crystal structure of the ball-milled soybean straw were greatly affected by the ball-milling pretreatment. The dissolved soybean straw could be regenerated by being poured into excess distilled water under rapid stirring. The total regenerated fraction yield decreased with the increase in the duration of ball-milling. Approximately 10% to 25% of the straw mass was lost in the dissolution-regeneration procedure. For comparison, ethylenediamine (EDA)-pretreated soybean straw was also completely dissolved in 8% LiCl/DMSO to form a homogeneous solution containing 1% straw after 24 h of continuous stirring. The dissolution-regeneration performance of soybean straw submitted to the EDA pretreatment was quite different due to the lack of vigorous ball-milling.
  • Researchpp 2318-2327Zhao, L., Lu, J., Zhou, Y., and Jiang, J. (2015). "Effect of low temperature cyclic treatments on modulus of elasticity of birch wood," BioRes. 10(2), 2318-2327.AbstractPDF
    The modulus of elasticity (MOE) of birch (Betula platyphylla) wood specimens with four different moisture content (MC) levels, i.e., water-saturated, green, air-dried, and oven-dried, were examined under a low temperature condition ranging from -196 °C (liquid nitrogen temperature) to +20 °C (room temperature). Dynamic mechanical analysis (DMA) was used to evaluate the dynamic viscoelastic properties before and after the low temperature treatment, while X-ray diffraction (XRD) was used to analyze the crystalline structure. The results showed that MOE with different MC increased after the low temperature treatment. Specimens with higher MCs were more affected by the treatment than specimens with lower MCs. However, the effect of low temperature treatment (within four times) on MOE was not significant (P > 0.05). Cyclic treatments of liquid nitrogen did not decrease wood MOE. As a structural material, wood has a better residence to low temperatures compared to concrete, in which mechanical properties decreased dramatically after one cycle of low to room temperature.
  • Researchpp 2328-2337Toda, M., Akiyama, T., Yokoyama, T., and Matsumoto, Y. (2015). "Quantitative examination of pre-extraction treatment on the determination of lignin content in leaves," BioRes. 10(2), 2328-2337.AbstractPDF
    It has been suggested that the Klason method overestimates the lignin content of non-wood tissues of plants. To evaluate the effect of pre-extraction treatments on lignin determination in leaves, nine kinds of pre-extraction treatment were applied to ginkgo leaves and zelkova leaves. The apparent lignin contents (lignin determination by the Klason method) of ginkgo and zelkova leaves without pre-extraction treatments were 30.7% and 42.6%, respectively. After the various pre-extraction treatments, the apparent lignin contents were still high. On the other hand, the yield of nitrobenzene oxidation products (NPs) per apparent lignin content was maintained at a very low level before and after pre-extraction treatments (maximum value was 6% for ginkgo leaf and 11% for zelkova leaf after extraction treatment) compared with the value from wood (25 to 60%). These results suggested that the Klason method overestimates the lignin content of leaves even after the pre-extraction treatments examined in this study. In addition, a considerable part of the sample from which NPs or neutral sugars originate was lost during these pre-extraction stages. These results implied that some parts of the cell wall components were also removed by these pre-extraction treatments.
  • Researchpp 2338-2349Zheng, X., Yin, Y., Jiang, W., Xing, L., and Pu, J. (2015). "Synthesis and characterization of low molecular weight chitosan," BioRes. 10(2), 2338-2349.AbstractPDF
    Chitosan can be widely used in many areas owing to its unique properties, although its poor solubility in water is still a limiting factor. In the present study, low molecular weight chitosan (LMWC) was prepared by degradation with NaClO so that chitosan was able to dissolve in water. Chitosan to liquor ratio, NaClO content, temperature, and time were considered variables of NaClO degradation, and the Box-Behnken design was used to determine optimal conditions. There was good agreement between the experimental data and their predicted counterparts. The optimum conditions for chitosan degradation were estimated to be 1:67.91 of chitosan to liquor ratio, 22.03% of NaClO content, a temperature of 90.3 °C, and a time of 3.07 h. It was found that synthesis under these optimized conditions achieved the lowest molecular weight (10,937.4 Daltons). In addition, Fourier transform infrared spectroscopy, X-ray diffractograms, and thermogravimetric analysis showed that the structure of LMWC was similar to the original chitosan, while the crystallinity and thermal stability decreased after degradation.
  • Researchpp 2350-2359Sri Aprilia, N. A., Hossain, M. S., Abdullah, C. K., Abdul Khalil, H. P. S., Rosamah, E., Dungani, R., Davoudpour, Y., and Zaidul, I. S. M. (2015). "Environmental durability of vinyl ester composites filled with carbonized jatropha seed shell," BioRes. 10(2), 2350-2359.AbstractPDF
    The durability of vinyl ester composites filled with carbonized jatropha seed shell was investigated in 5% NaOH solution, 5% HCl solution, and distilled water for 12 months. The environmental durability of the composites was determined by measuring weight changes, flexural properties, and tensile properties. Results showed weight gain and changes in the mechanical properties of the composites due to the soaking time in alkaline, acidic, and neutral environments. It was observed that vinyl ester composites had the highest tensile properties in alkaline environments. The highest flexural properties of the vinyl ester composites were observed in an alkaline environment. Scanning electron microscope image analysis revealed that the surface of the vinyl ester composites was rough and that the original luster was lost after soaking in alkaline solution, acidic solution, and distilled water for 12 months.
  • Researchpp 2360-2375Moser, C., Lindström, M. E., and Henriksson, G. (2015). "Toward industrially feasible methods for following the process of manufacturing cellulose nanofibers," BioRes. 10(2), 2360-2375.AbstractPDF
    Nanocellulose is a recently developed form of cellulose that has the potential to be used in many different industries, ranging from food to high-performance applications. This material is commercially manufactured through the homogenization of chemical pulps, but the process is energy-consuming and is still an important subject for development. Simple, robust methods are required for the quality control and optimization of industrial nanocellulose production. In this study, a number of different methods, based on different principles of monitoring the manufacture of cellulose nanofibers were evaluated and compared for five different nanocellulose qualities, both for their resolution and robustness/ease. Methods based on microscopy, light scattering, centrifugation, and viscosity were examined and all appeared useful for observing the manufacturing process during its initial stage. However, only methods based on centrifugation, turbidity, and transmittance yielded reliable data for the entire manufacturing process. Of these methods, transmittance measurement may be the best candidate for routine use because the method is simple, rapid, and only requires spectrophotometer equipment.
  • Researchpp 2376-2391Chen, C., Mao, S., Wang, J., Bao, J., Xu, H., Su, W., and Dai, H. (2015). "Application of ultrafiltration in a paper mill: Process water reuse and membrane fouling analysis," BioRes. 10(2), 2376-2391.AbstractPDF
    High water consumption is a major environmental problem that the pulp and paper industry is facing. Ultrafiltration (UF) can be used to remove the dissolved and colloidal substances (DCS) concentrated during the recycling of white water (the process water) to facilitate the reuse of white water and reduce fresh water consumption. However, membrane fouling limits the application of UF in this industry. In this study, super-clear filtrate obtained from a fine paper mill was purified with a polyethersulfone (PES) ultrafiltration membrane to evaluate the reuse performance of the ultrafiltrate. The membrane foulants were characterized by scanning electron microscopy, energy-dispersive spectrophotometry, attenuated total reflection-fourier transform infrared spectroscopy, and gas chromatography-mass spectrometry. The results indicate that the retention rate of stock and the strength properties of paper increased when the ultrafiltrate was reused in the papermaking process compared to when super-clear filtrate was used. The reversible membrane foulants during ultrafiltration accounted for 85.52% of the total foulants and primarily originated from retention aids, drainage aids, and wet strength resins, while the irreversible adsorptive foulants accounted for 14.48% and mostly came from sizing agents, coating chemicals, and others. Moreover, the presence of dissolved multivalent metal ions, especially Ca2+, accelerated membrane fouling.
  • Researchpp 2392-2405Zhu, X., and Sun, L. (2015). "Multiscale analysis on electrical properties of carbon fiber-reinforced wood composites," BioRes. 10(2), 2392-2405.AbstractPDF
    Carbon fiber was selected as a reinforcement for the manufacture of composite materials. Electrical properties of carbon fiber reinforced wood composites (CFRWCs) were studied by multiscale analysis, which is an all-rounded method to analyze CFRWCs from the macroscopic area to the microcosmic field. It was found that the insulated wood fiber materials could conduct electricity after adding a certain proportion of carbon fibers. The dielectric constants and the capacitances of CFRWCs increased gradually with increasing carbon fiber content in the composites from 55 wt.% to 75 wt.% when a certain condition prevails. However, the loss tangents and the surface resistivities of CFRWCs decreased as the carbon fiber content was increased continuously. The data of surface resistivity represented a negative growth situation with increasing temperature from 20 °C to 120 °C and exhibited a negative temperature coefficient (NTC) effect. The movement of electrons was also analyzed due to temperature rise.
  • Researchpp 2406-2417Yu, L., Tatsumi, D., Zuo, S., and Morita, M. (2015). "Promotion of crystal growth on biomass-based carbon using phosphoric acid treatments," BioRes. 10(2), 2406-2417.AbstractPDF
    The effect of phosphoric acid treatments on graphitic microcrystal growth of biomass-based carbons was investigated using X-ray diffraction, infrared spectroscopy, and Raman spectroscopy. Although biomass-based carbons are believed to be hard to graphitize even after heat treatments well beyond 2000 °C, we found that graphitic microcrystals of biomass-based carbons were significantly promoted by phosphoric acid treatments above 800 °C. Moreover, twisted spindle-like whiskers were formed on the surface of the carbons. This suggests that phosphorus-containing groups turn graphitic microcrystalline domains into graphite during phosphoric acid treatments. In addition, the porous texture of the phosphoric acid-treated carbon has the advantage of micropore development.
  • Researchpp 2418-2424Liu, S., Wang, Q., Yang, G., Chen, J., Ni, Y., and Ji, X. (2015). "Kinetics of viscosity decrease by cellulase treatment of bleached hardwood kraft-based dissolving pulp," BioRes. 10(2), 2418-2424.AbstractPDF
    A dissolving pulp of low cellulose viscosity represents a pulp of high quality; hence, it is often necessary to decrease the initial dissolving pulp viscosity. One so-called environmentally friendly approach to further reducing the dissolving pulp viscosity is to treat the dissolving pulp with cellulase enzymes. In this study, the kinetics of the decrease in cellulose viscosity during a cellulase treatment was investigated. The study showed that the kinetics of the cellulose degradation during a cellulase treatment can be divided into at least two phases, where the initial phase is very fast and the final phase is very slow. The kinetic two-phase model for the viscosity degradation that has been developed in this project can be used to predict and control the final pulp viscosity of dissolving pulps.
  • Researchpp 2425-2432Li, Z., Xiao, D., Kong, Y., and Ge, Y. (2015). "Enhancing lead adsorption capacity by controlling the chain length of alkyl amine grafted lignin," BioRes. 10(2), 2425-2432.AbstractPDF
    The adsorption capacity of lignin for lead can be controlled by varying the chain length of alkyl, attaching the amine to the lignin surface from C2 (ethyl) to C18 (octadecyl). Altering the chain length had a strong effect on the contribution of amine groups in the adsorption of lead ions by lignin. The adsorption capacity increased 105.0% as the chain length increased to butyl (C4); however, further chain lengths, up to C18, provided no additional benefit, and in some cases even hindered the adsorption capacity of lignin. A short-chain alkyl (C4) group enhanced the beneficial amine contributions for metal ion adsorption, which resulted from the efficient inductive effectiveness of the alkyl groups.
  • Researchpp 2433-2443Ateş, S., Gür, M., Özkan, O. E., Akça, M., Olgun, C., and Güder, A. (2015). "Chemical contents and antifungal activity of some durable wood extractives vs. Pleurotus ostreatus," BioRes. 10(2), 2433-2443.AbstractPDF
    The total phenolic content (TPC), total flavonoid content (TFC), phenolic compounds, and antifungal activity of olive (Olea europaea var. sylvestris) and juniper (Juniperus foetidissima) sapwood and heartwood extractives were examined. The extractives were obtained using methanol solvents. The different compounds in extractives were identified and quantified. The antifungal activities of different parts of the olive and juniper wood extractives were determined in vitro. Pleurotus ostreatus mycelium was used for the antifungal activity experiment. Extractive compounds obtained from olive and juniper woods were found to be effective, natural antifungal agents.
  • Researchpp 2444-2460Zhao, Z., and Umemura, K. (2015). "Investigation of a new natural particleboard adhesive composed of tannin and sucrose. 2. Effect of pressing temperature and time on board properties, and characterization of adhesive," BioRes. 10(2), 2444-2460.AbstractPDF
    In a previous study by the authors, particleboard was manufactured using a new natural adhesive composed of tannin and sucrose. The optimal ratio between tannin and sucrose was 25/75, and the suitable resin content was 30 to 40 wt%. In this study, the effects of hot pressing temperature and hot pressing time on board properties were investigated. The optimal values for the hot pressing temperature and hot pressing time were found to be 220 °C and 10 min, respectively. When the particleboard was made under these optimum conditions, the physical properties of the particleboard bonded with tannin and sucrose met the requirement of the JIS A 5908 type 18 standard (2003). Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), insoluble matter, and Fourier transform infrared spectroscopy (FT-IR) tests were carried out. The results of TGA and DSC measurements showed that the weight loss and endothermic reaction of the adhesive composed of tannin and sucrose at a ratio of 25/75 occurred at 204 and 215 °C, respectively. When the adhesive was heated at 220 °C for longer than 10 min, the level of insoluble matter was higher than 70 wt%. FT-IR analysis showed the existence of a furan ring, a carbonyl group, and dimethylene ether bridges in the cured adhesives before and after the boiling treatment. When the heating time was longer than 10 min, no further change of chemical structure was observed.
  • Researchpp 2461-2478Joutsimo, O. P., and Giacomozzi, D. (2015). "Changes in cell wall structure during kraft processing of Pinus radiata," BioRes. 10(2), 2461-2478.AbstractPDF
    Comparison of industrial and laboratory pulps from Pinus radiata showed higher energy requirement and lower tear index at the same tensile strength in the case of industrial pulps. Chemical differences between pulps were negligible and cannot explain the strength differences observed. Morphology of the fibers changed during processing with an increase in kinks and curls for industrial pulps. Increased twists and wrinkling in mill fibers were observed based on scanning electron microscopy images. Results from water retention value and fiber saturation point measurements showed reduced water holding ability of industrial fibers. Simons’ stain and hydrogen nuclear magnetic resonance confirmed a higher proportion of macropores in the fibers of industrial compared to laboratory pulps. Evidence supports the presence of both micropore closure and creation of new mesopores and macropores during industrial processing. A combination of fiber damages, porosity changes, and induced deformations seems to play the main role in the lower strength properties of industrial pulps when compared to laboratory pulps.
  • Researchpp 2479-2491Panov, D., and Terziev, N. (2015). "Durability of epoxi-oil modified and alkoxysilane treated wood in field testing," BioRes. 10(2), 2479-2491.AbstractPDF
    Increased interest in oils and silicones as hydrophobic agents creates the need for testing, with the aim of better understanding their field performance and preparation for an eventual market entrance of these products. This study reveals the aboveground test performance of wood impregnated with epoxidised linseed oil (ELO) and organofunctional alkoxysilanes and compares the achieved results with the significantly more severe inground exposure and initial laboratory tests. Since ELO and siloxanes are not active ingredients, they were combined with fungicides for better performance. Various oil and alkoxysilane retentions and combinations with boric acid, organic fungicides, and creosote were impregnated in wood and tested. Untreated, chromium-copper-arsenate (CCA)-treated and thermally modified samples served as references. Long-term aboveground and inground testing of the studied formulations enforced the conclusion that ELO combined with biocides is suitable protective formulation for timber in both above- and in-ground exposure. Two alkoxysilanes were more effective in timber exposed aboveground. No decay was registered in the ELO and alkoxysilane treated lap-joint samples, while the untreated controls were close to failure after five years of exposure.
  • Researchpp 2492-2505Wongratpanya, K., Imjongjairak, S., Waeonukul, R., Sornyotha, S., Phitsuwan, P., Pason, P., Nimchua, T., Tachaapaikoon, C., and Ratanakhanokchai, K. (2015). "Multifunctional properties of glycoside hydrolase family 43 from Paenibacillus curdlanolyticus strain B-6 including exo-β-xylosidase, endo-xylanase, and α-L-arabinofuranosidase activities," BioRes. 10(2), 2492-2505.AbstractPDF
    The glycoside hydrolase family 43 from Paenibacillus curdlanolyticus strain B-6 (GH43B6) exhibited multifunctional properties, including exo-β-xylosidase, endo-xylanase, and α-L-arabinofuranosidase enzymatic activities. GH43B6 released xylose as a hydrolysis product from the successive reduction of xylooligosaccharides as a result of exo-β-xylosidase activity. Moreover, GH43B6 also predominantly released xylose from low-substituted xylan derived from birchwood. However, when the highly substituted rye flour arabinoxylan was used as a substrate, exo-β-xylosidase activity changed to endo-xylanase activity, indicating that the enzymatic property of GH43B6 is influenced by the substituted side groups of xylan. For α-L-arabinofuranosidase, arabinose was released from short-chain substrates including p-nitrophenyl-α-L-arabinofuranoside and α-L-Araf-(1→2)-[α-L-Araf-(1→3)]-β-D-Xylp. This study reports the novel trifunctional properties of GH43B6 containing exo- and endo-activity together with xylanolytic debranching enzymatic activity, which increases its potential for application in lignocellulose-based biorefineries.
  • Researchpp 2506-2510Oghbaie, M., Mirshokraie, S. A., and Massoudi, A. H. (2015). "Investigating the stereochemistry of α-carbon in lignin preparations and lignin model compounds using 77Se NMR," BioRes. 10(2), 2506-2510.AbstractPDF
    Studying the stereochemistry of lignin as a natural chiral polymer may have scientific and technical importance regarding the behavior of lignin and delignification processes. In the present study, the hydroxyl groups of α-carbon (chiral center) in phenyl propane structural units of lignins and two model compounds were selenated. Then, the 77Se nuclear magnetic resonance (NMR) spectra of the selenated samples were examined in order to determine the ratio of diastereomers (erythro and threo). The results revealed that lignins are a mixture of different ratios of two diastereomers. This finding may have scientific importance and practical impacts on the chemistry of delignification processes and other related phenomena in the domain of pulp and paper sciences.
  • Researchpp 2511-2517Zhang, C., Fu, S., and Liu, Y. (2015). "Hydrolyzability of pectic anionic substances in process waters by pectinases," BioRes. 10(2), 2511-2517.AbstractPDF
    In this paper, the efficiency and mechanisms of two pectinases (pectate lyase (PL) and alkaline pectinase (AL)) to hydrolyze model pectic substances and dissolved and colloidal substances (DCS) of Masson pine bleached chemithermomechanical pulp (BCTMP) were investigated. The cationic demand values of model polygalacturonic acid and DCS could be reduced to about 20% and 60 to 70% by these two pectinases, respectively. However, due to the unmethylated form of the pectic substances in DCS of BCTMP, PL is more efficient than AL. The hydrolysis mechanism of polygalacturonic acid with PL was investigated. The results showed that there was no need to hydrolyze the polymeric pectic substance to their monomers, since a minimum average degree of polymerization (DP) of 6.0 was required for pectic acid to interact strongly with cationic polymers and reduce the efficiency of the latter.
  • Researchpp 2518-2525Ji, X., Chen, J., Wang, Q., Tian, Z., Yang, G., and Liu, S. (2015). "Boosting oxygen delignification of poplar kraft pulp by xylanase pretreatment," BioRes. 10(2), 2518-2525.AbstractPDF
    Enhancement of oxygen delignification is critical to improve subsequent bleaching efficiency while being environmentally compatible. In the present study, xylanase was used to improve the delignification process of poplar kraft pulp. Results showed that the kappa number reduction ratio (KRR) of 14.5% was achieved for the pulp under xylanase-assisted oxygen delignification processes when compared to the control without xylanase treatment. Other pulp properties, such as intrinsic viscosity and brightness, also improved somewhat; i.e., viscosity increased by 28 mL/g units and ISO brightness increased 1.4% points. Furthermore, 31P-NMR was employed to characterize the chemical structure of the residual lignin of the pulps before and after oxygen delignification. It showed that the condensed phenolic and syringyl hydroxyl groups decreased significantly for the xylanase-assisted oxygen-delignified pulps.
  • Researchpp 2526-2548Ratnasingam, J., Ramasamy, G., Wai, L. T., Senin, A. L., and Muttiah, N. (2015). "The prospects of rubberwood biomass energy production in Malaysia," BioRes. 10(2), 2526-2548.AbstractPDF
    Rubber has been shown to be one of the most important plantation crops in Malaysia, and rubber tree biomass has widespread applications in almost all sectors of the wood products manufacturing sector. Despite its abundance, the exploitation of rubberwood biomass for energy generation is limited when compared to other available biomass such as oil palm, rice husk, cocoa, sugarcane, coconut, and other wood residues. Furthermore, the use of biomass for energy generation is still in its early stages in Malaysia, a nation still highly dependent on fossil fuels for energy production. The constraints for large scale biomass energy production in Malaysia are the lack of financing for such projects, the need for large investments, and the limited research and development activities in the sector of efficient biomass energy production. The relatively low cost of energy in Malaysia, through the provision of subsidy, also restricts the potential utilization of biomass for energy production. In order to fully realize the potential of biomass energy in Malaysia, the environmental cost must be factored into the cost of energy production.
  • Researchpp 2549-2559Xu, K., Zheng, Z., Chen, T., Li, K., and Zhong, T. (2015). "Study on the torque rheological behavior of wood flour/chitosan/polyvinyl chloride composites," BioRes. 10(2), 2549-2559.AbstractPDF
    Torque rheological properties of wood flour/chitosan/PVC (WF/CS/PVC) compounds were measured by a torque rheometer using roller-style rotating blades at various setting temperatures (175 and 185 °C) and rotation speeds (30, 45, 60, and 75 rpm). The torque rheological parameters were calculated based on the Marquez model and Arrhenius equation. The torque rheological curves of WF/CS/PVC composites were similar to WF/PVC composites without chitosan. The classical Marquez model was verified to be suitable for both WF/PVC and WF/CS/PVC composites. Specifically, the activation energy (ΔE), n value, and range of C(n)m for the former and latter were 27.698 kJ·mol-1 and 29.237 kJ·mol-1, 0.382 and 0.381, and 4.415 to 5.749 N·m·sn and 4.652 to 6.079 N·m·sn, respectively. The rheological properties of WF/CS/PVC composites did not show a great qualitative enhancement compared to WF/PVC composites.
  • Researchpp 2560-2569Tang, Q., Bian, H., Ran, J., Zhu, Y., Yu, J., and Zhu, W. (2015). "Hydrogen-rich gas production from steam gasification of biomass using CaO and a Fe-Cr water-gas shift catalyst," BioRes. 10(2), 2560-2569.AbstractPDF
    The technical feasibility of using calcium oxide (CaO) as a sorbent for CO2 and Fe-Cr as a catalyst for the water-gas shift (WGS) reaction using syngas for the steam gasification of biomass was investigated. The effects of temperature, steam to biomass mass ratio, CaO to biomass molar ratio, and Fe-Cr WGS catalyst on gas composition were studied. Within a temperature range of 250 °C to 550 °C, the H2 concentration increased from 1.2% to 17.1%, with a total increase of 16%. As the steam rate increased within the range of 0 kg/h to 0.12 kg/h, the maximum value of H2 concentration increased from 12.1% to 17.13%, with a total increase of 5%. As the CaO to biomass molar ratio was increased from 0 to 2, the CO2 concentration demonstrated a minimum value of 1.3%, and the H2 concentration exhibited a maximum value of 53.1%. A catalyst to biomass mass ratio of 1 resulted in the minimum value of CO2 concentration, which decreased from 7.9%, in the absence of CaO, to 1.6%. A CaO to biomass molar ratio of 1.5 resulted in the maximum value of H2 concentration, which increased from 27.6%, in the absence of CaO, to 63%.
  • Researchpp 2570-2584Mansour, M. M. A., Abdel-Megeed, A., Nasser, R. A., and Salem, M. Z. M. (2015). "Comparative evaluation of some woody tree methanolic extracts and paraloid B-72 against phytopathogenic mold fungi Alternaria tenuissima and Fusarium culmorum," BioRes. 10(2), 2570-2584.AbstractPDF
    Natural compounds from certain timber trees are highly valued and recommended to protect wood and wood products against mold fungi. This study highlighted the use of some natural extracts and Paraloid B-72 against the growth of two mold fungi, namely Alternaria tenuissima and Fusarium culmorum. From the in vitro experiment, the methanol extracts of Callistemon viminalis bark were effective against the growth of F. culmorum, as were Magnolia grandiflora leaves against A. tenuissima.Environmental scanning electron microscopy (ESEM) and electron dispersive X-ray spectroscopy (EDX) analysis of treated Acacia saligna wood with the two fungi and Paraloid B-72 demonstrated the clear hyphal growth of F. culmorum and A. tenuissima and changes in elemental chemical composition. After three months, no fungal growth on the wood surface treated with the methanol extract of M. pomifera bark was found. After three months of treating wood with Paraloid B-72 at 5% and 10%, the mold growth was visible. Almost all of the wood treated with methanol extracts showed growth of the A. tenuissima hypha, as well as some contamination by other microorganisms, except for the wood treated with the methanol extract of M. pomifera bark.
  • Researchpp 2585-2596Chang, H., Tu, K., Wang, X., and Liu, J. (2015). "Facile preparation of stable superhydrophobic coatings on wood surfaces using silica-polymer nanocomposites," BioRes. 10(2), 2585-2596.AbstractPDF
    Superhydrophobic organic-inorganic composite nanocoatings were fabricated on the intrinsically heterogeneous surfaces of wood using silica-polymer hybrid materials, which were prepared through sol-gel chemistry using tetraethoxysilane (TEOS) as an inorganic precursor and hexadecyltrimethoxysilane (HDTMS) as an organic modifier. The long-chain HDTMS acts not only as a hydrophobic agent to lower the surface free energy of the silica particles but also as a bonding agent to aggregate the nanoparticles by polymerization. The degree of aggregation of the silica particles in the coating can be controlled by adjusting the initial concentration of HDTMS, and hence the surface morphology and roughness of the coated wood are tuned. When the concentration of HDTMS reaches a critical level, the formed aggregates of silica particles in combination with the inherent microscale roughness of wood appear to create hierarchical micro/nanostructures on the wood substrate, allowing for the generation of superhydrophobicity. The silica-polymer hybrid coatings on the wood surface are robust enough to withstand high humidity as well as strong acid and alkali whilst retaining its superhydrophobicity. The coatings also exhibit satisfactory durability against water leaching without significantly changing its hydrophobicity, highlighting their potential for outdoor applications.
  • Researchpp 2597-2608Yong, C. K., Ching, Y. C., Chuah, C. H., and Liou, N. S. (2015). "Effect of fiber orientation on mechanical properties of kenaf-reinforced polymer composite," BioRes. 10(2), 2597-2608.AbstractPDF
    The increase of environmental awareness has led to interest in the use of materials with eco-friendly attributes. In this study, a sandwich composite was developed from polyester and kenaf fiber with various orientation arrangements. Polyester/kenaf sandwich composite was fabricated through the combination of a hand lay-up process and cold compression. The tensile, flexural, and Izod impact tests of the sandwich composites were evaluated by using a universal tensile tester and an impact tester. The thermal stability of polyester/kenaf sandwich composite and plywood were investigated by using a thermogravimetric analyser. Results showed that the polyester/kenaf sandwich composite with kenaf fiber in anisotropy orientation achieved the highest mechanical properties. The kenaf fiber in anisotropic orientation could absorb the impact energy and allow the sandwich composite to withstand greater impact forces compared to composite with fiber in perpendicular or isotropic orientations. The polyester/kenaf sandwich composite also showed higher thermal stability compared to a conventional plywood sheet. Thus, the fabrication of polyester/kenaf sandwich composite with kenaf fiber in an anisotropic orientation design has great potential to replace plywood sheets for beam construction applications.
  • Researchpp 2609-2625Sharara, M. A., and Sadaka, S. S. (2015). "Gasification of phycoremediation algal biomass," BioRes. 10(2), 2609-2625.AbstractPDF
    Microalgae have been utilized in wastewater treatment strategies in various contexts. Uncontrolled algal species are a cheap and effective remediation strategy. This study investigates the thermochemical potential of wastewater treatment algae (phycoremediation) as a means to produce renewable fuel streams and bio-products. Three gasification temperature levels were investigated in an auger gasification platform: 760, 860, and 960 °C. Temperature increases resulted in corresponding increases in CO and H2 concentrations in the producer gas from 12.8% and 4.7% at 760 °C to 16.9% and 11.4% at 960 °C, respectively. Condensable yields ranged between 15.0% and 16.6%, whereas char yields fell between 46.0% and 51.0%. The high ash content (40% on a dry basis) was the main cause of the elevated char yields. On the other hand, the relatively high yields of condensables and a high carbon concentration in the char were attributed to the low conversion efficiency in this gasification platform. Combustion kinetics of the raw algae, in a thermogravimetric analyzer, showed three consecutive stages of weight loss: drying, devolatilization, and char oxidation. Increasing the algae gasification temperature led to increases in the temperature of peak char oxidation. Future studies will further investigate improvements to the performance of auger gasification.
  • Researchpp 2626-2641Moniz, P., Lino, J., Duarte, L. C., Roseiro, L. B., Boeriu, C. G., Pereira, H., and Carvalheiro, F. (2015). "Fractionation of hemicelluloses and lignin from rice straw by combining autohydrolysis and optimised mild organosolv delignification," BioRes. 10(2), 2626-2641.AbstractPDF
    An integrated strategy was followed to valorise rice straw, one of the most relevant biomass feedstocks available worldwide, to selectively recover solubilised hemicelluloses and lignin. The pathway encompassed the use of autohydrolysis to hydrolyse the hemicelluloses and an ethanol-based organosolv process to solubilise lignin. Several autohydrolysis conditions were assayed with the best results obtained at 210 ºC (log R0 4.15), which enabled high removal of hemicelluloses, yielding an oligosaccharide-rich hydrolysate and a treated biomass with low content of hemicelluloses and enriched in cellulose and lignin. The effects of ethanol concentration (5 to 75%), and reaction time (0 to 24 h) on lignin removal under mild temperature (30 ºC) were studied. In optimal conditions (60.5% ethanol, 24h) the delignification yield reached 42%, whereas glucan solubilisation was below 17%. Lignin solubilisation yield was not influenced by the organosolv treatment duration while ethanol concentration favored the delignification up to 60.5% ethanol. The organosolv liquors contained economic interesting lignin-derived compounds such as vanillin, ferulic, and coumaric acids. The chemical composition and enzymatic digestibility of the treated biomass from autohydrolysis and organosolv delignification were compared, with the latter presenting an almost 10% higher enzymatic digestibility than the former.
  • Researchpp 2642-2655Febrianto, F., Jang, J. H., Lee, S. H., Santosa, I. A., Hidayat, W., Kwon, J. H., and Kim, N. H. (2015). "Effect of bamboo species and resin content on properties of oriented strand board prepared from steam-treated bamboo strands," BioRes. 10(2), 2642-2655.AbstractPDF
    The objective of this research was to evaluate the effect of bamboo species and resin content on the physical and mechanical properties of oriented strand boards (OSBs) prepared from steam-treated bamboo strands. The strands from three species of Indonesian bamboo, namely Andong (Gigantochloa verticillata), Betung (Dendrocalamus asper), and Ampel (Bambusa vulgaris), were steamed at 126 °C for 1 h at a pressure of 0.14 MPa. Three-layered OSBs with the core layer oriented perpendicularly to the face layers were prepared by bonding them together with 3 to 5% methylene diphenyldiisocyanate (MDI) resin based on oven-dried strands and with the addition of 1% paraffin. The strand compositions for the face, core, and back layers were 25%, 50%, and 25%, respectively. The slenderness ratios and aspect ratios of the strands ranged from 71.02 to 76.60 and from 2.96 to 3.02, respectively. The physical and mechanical properties of the OSBs fabricated from Andong and Betung were better than those from Ampel, and the properties of all OSBs were improved by increasing their resin content. OSBs from Betung with 3 to 5% resin content and those from Andong and Ampel with 4 to 5% resin content showed strength retention of more than 50%, which means they can be used for exterior structural applications. Except for OSBs fabricated from Ampel with 3% resin content, the properties of all OSBs prepared in this study were higher than the minimum values required by the CSA O437.0 (grade O-1) standard (2011).
  • Researchpp 2656-2666Zhang, S., He, B., Zhao, L., and Zhou, J. (2015). "Application of carbon footprint assessment methodology to the case of coated ivory board," BioRes. 10(2), 2656-2666.AbstractPDF
    The pulp and paper industry, which is closely related to national economic and social development, is an important industry but also contributes high carbon emissions. Therefore, with the advent of the low-carbon economic era, ways to reduce the carbon emissions and to bring about a low-carbon industrial transition of the pulp and paper industry is becoming one of the important academic projects. A system for carbon footprint assessment, namely the Publicly Available Specification (PAS) 2050 methodology, is introduced in this paper. Based on the analysis and assessment of the carbon footprint (CO2 equivalent emissions) for the Coated Ivory Board production lines, it was used to provide a scientific basis and approach for reduction of carbon emissions and formulate the corresponding measures for carbon emissions reduction of China's pulp and paper industry. The business to business carbon footprint, for which steps of the life cycle are included in Coated Ivory Board production, was analyzed and calculated. The results showed that there were 888 kg of CO2 equivalent emissions per metric ton of Coated Ivory Board, in which the largest part, accounting for 57.5%, was associated with purchased electricity, followed by fuel oil at 40.2%, and others accounted for 2.3% of the CO2 equivalent emissions.
  • Researchpp 2667-2680Li, Z., Li, J., Xu, J., and Mo, L. H. (2015). "Clean bleaching engineering practice for bagasse pulp: Totally chlorine-free and elemental chlorine-free bleaching realized with the same production line," BioRes. 10(2), 2667-2680.AbstractPDF
    The experimental research, process design principles, and engineering practice of a bagasse pulp production line that could run both totally chlorine-free (OP)Q(PO) and elemental chlorine-free (OP)D(EOP) bleaching sequences are discussed in this paper. Under specified process conditions, the oxygen delignification rate was up to 50% and the brightness of unbleached pulp increased. The (OP)Q(PO) sequence bleached pulp had a brightness of 83.1% ISO and an intrinsic viscosity of 888 mL/g, and the (OP)D(EOP) sequence bleached pulp had a brightness of 85.7% ISO and an intrinsic viscosity of 905 mL/g. Pulp quality produced from both bleaching sequences was better than pulp bleached by the chlorination, alkaline extraction, and hypochlorite (CEH) sequence. The wastewater was discharged only from the Q or D stage, and the chemical oxygen demand (COD) of Q or D stage was about 650 mg/L or 1100 mg/L, respectively. It was easy to alternate between these two bleaching sequences, and the bleached pulp quality from these sequences was stable.
  • Researchpp 2681-2690Mohammed, I. Y., Kazi, F. K., Abakr, Y. A., Yusuf, S., and Abdur Razzaque, M. (2015). "Novel method for the determination of water content and higher heating value of pyrolysis oil," BioRes. 10(2), 2681-2690.AbstractPDF
    This research provides a novel approach for the determination of water content and higher heating value of pyrolysis oil. Pyrolysis oil from Napier grass was used in this study. Water content was determined with pH adjustment using a Karl Fischer titration unit. An equation for actual water in the oil was developed and used, and the results were compared with the traditional Karl Fischer method. The oil was found to have between 42 and 64% moisture under the same pyrolysis condition depending on the properties of the Napier grass prior to the pyrolysis. The higher heating value of the pyrolysis oil was determined using an oil-diesel mixture, and 20 to 25 wt% of the oil in the mixture gave optimum and stable results. A new model was developed for evaluation of higher heating value of dry pyrolysis oil. The dry oil has higher heating values in the range between 19 and 26 MJ/kg. The developed protocols and equations may serve as a reliable alternative means for establishing the actual water content and the higher heating value of pyrolysis oil.
  • Researchpp 2691-2698Pérez-Sariñana, B. Y., Saldaña-Trinidad, S., Guerrero-Fajardo, C. A., Santis-Espinosa, L. F., and Pathiyamattom-Joseph, S. (2015). "A simple method to determine bioethanol production from coffee mucilage, verified by HPLC," BioRes. 10(2), 2691-2698.AbstractPDF
    This paper proposes a method to determine bioethanol concentration that uses a pycnometer verified with a high performance liquid chromatography (HPLC) technique; it is a simple tool to determine the density of liquids for getting information about the ethanol concentration. The results showed that the sugar concentration affected the bioethanol concentration. A lower initial sugar concentration of 26.5 g/L generated higher yield of 45.3% sugar to bioethanol and a fractional or relative yield of 88.74%. Significance tests were used to compare the two experimental means, revealing that the pycnometer method and HPLC provide the same bioethanol concentration with joint variances of 2.269, 0.242, and 0.112 for 3 different tests with initial sugar concentrations of 26.486 g/L, 49.043 g/L, and 68.535 g/L, respectively. This study established and developed a methodology to determine bioethanol concentration from coffee mucilage by the proposed method.
  • Researchpp 2699-2718Kangas, H., Hakala, T. K., Tamminen, T., Määttänen, M., Rovio, S., Liitiä, T., and Poppius-Levlin, K. (2015). "Optimisation of acetic acid lignofibre organosolv process," BioRes. 10(2), 2699-2718.AbstractPDF
    Birch wood chips were cooked in acetic acid in the presence of phosphinic acid according to the Lignofibre (LGF) organosolv process. The cooking trials were performed according to an experimental design with process time, temperature, and the presence (or absence) of alkaline pre-extraction as the factors. Delignification was enhanced by increased temperature and alkaline pre-extraction. Alkaline extraction also limited xylose hydrolysis, as well as the further degradation of xylose into furfural. Degradation and condensation reactions began to take place between dissolved carbohydrates and lignin at higher temperatures and longer cooking times. Formation of pseudolignin, most likely because of reactions between lignin and furfural, was also observed under the harshest cooking conditions. To avoid these unwanted side-reactions, minimise viscosity losses, and preserve the yield, the LGF process time should be limited to 3 to 4 h at 150 °C.
  • Researchpp 2719-2731Chau, T., Ma, E., and Cao, J. (2015). "Moisture adsorption and hygroexpansion of paraffin wax emulsion-treated southern pine (Pinus spp.)," BioRes. 10(2), 2719-2731.AbstractPDF
    Moisture adsorption and hygroexpansion behaviors of southern pine (Pinus spp.) treated with 0.5, 1, and 2% concentrations of paraffin wax emulsion were investigated. The specimens, 4 mm along the grain and 20 mm in radial and tangential directions, were exposed to seven different relative humidity conditions of 11, 22, 33, 45, 60, 75, and 92% for adsorption at 30 °C, which was controlled by a self-designed temperature conditioning chamber. Weights and transverse dimensions of the specimens were measured at certain time intervals during the adsorption processes. Results showed that paraffin wax emulsion treatments could reduce both equilibrium moisture content and adsorption rate. Additionally, paraffin wax emulsion treatments also improved dimensional stability, as indicated by estimation of the humidity expansion coefficient (Y) as well as moisture expansion coefficient (X).
  • Researchpp 2732-2743Park, J., Shin, H., Yoo, S., Zoppe, J. O., and Park, S. (2015). "Delignification of lignocellulosic biomass and its effect on subsequent enzymatic hydrolysis," BioRes. 10(2), 2732-2743.AbstractPDF
    The effect of delignification on the enzymatic hydrolysis of biomass was investigated to determine how different delignification processes affect enzymatic hydrolysis conversion yields. Oxygen, hydrogen peroxide, and sodium chlorite treatments were performed, and the structural and chemical changes in the biomass were evaluated. Sodium chlorite delignification proved the most effective process to remove lignin in hardwood samples, followed by oxygen delignification. Hydrogen peroxide delignification was not as effective as the other two methods. As for the enzymatic conversion of carbohydrates after delignification processes on hardwood, oxygen and sodium chlorite treatments substantially improved conversion yields as the number of successive treatments was increased, compared to untreated hardwood samples. Changes in α-cellulose after delignification were less substantial than those of hardwood samples, and corresponding conversion yields were also lower. Delignification-induced structural changes in treated substrates might be responsible for the changes in carbohydrate conversion yield observed following subsequent enzymatic hydrolysis.
  • Researchpp 2744-2754Xie, T., Liu, W., Chen, T., and Qiu, R. (2015). "Mechanical and thermal properties of hemp fiber-unsaturated polyester composites toughened by butyl methacrylate," BioRes. 10(2), 2744-2754.AbstractPDF
    Hemp fiber-reinforced unsaturated polyester (UPE) composites were prepared by hand lay-up compression molding. The UPE resins were modified with butyl methacrylate (BMA) to improve the flexibility and toughness of the hemp-UPE composites. The results indicate that the toughness of the composites significantly increased as BMA usage increased. Compared to the unmodified UPE composites, the composites obtained from BMA-modified UPE resins had 27.4, 63.0, and 36.6% greater elongation at break, flexural strain, and impact strength, respectively. The optimum BMA usage to achieve an adequate balance of stiffness and toughness is 20 to 30%. Dynamic mechanical analysis (DMA) indicated that incorporation of BMA significantly decreased the storage modulus and glass transition temperature of the composites and increased its damping parameter due to the introduction of flexible segments into the UPE resins. Thermogravimetric analysis showed that the thermal stability of the composites decreased slightly following the incorporation of BMA. Scanning electron microscopy images of the impact-fractured surfaces of the composites revealed that BMA incorporation improved interfacial adhesion between hemp fibers and UPE matrices and that the main mechanism for the increase in the toughness of the composites was the added ductility of the matrices.
  • Researchpp 2755-2772Yu, D., Liu, W., Li, Y., Wang, H., and Li, G. (2015). "Dodecenylsuccinic anhydride pickering emulsion stabilized by montmorillonite nanoparticles modified with sodium flouride," BioRes. 10(2), 2755-2722.AbstractPDF
    Processing convenience and paper-sizing flexibility frequently require the delivery of alkenylsuccinic anhydride oil as emulsion. The shelf life of the oil is achieved kinetically, in most cases via the addition of surfactants such as cationic starch or a synthetic polymer, which are the subject of increasing scrutiny with regard to their environmental impact. The modification of montmorillonite nanoparticle with sodium fluoride was found to decrease the interfacial tension between dodecenylsuccinic anhydride (DDSA) and aqueous dispersion and to change the wettability of montmorillonite, which benefits the preparation of DDSA-in-water emulsions with enhanced stability, small droplet size, and improved hydrolysis resistance. Adjusting the pH and particle concentration of aqueous solution effectively improved the stability of DDSA emulsion. Catastrophic phase inversion from w/o (water-in-oil) to o/w (oil-in-water) was investigated by monitoring the variation of emulsion conductivity with increasing oil volume fraction. Evidence of the transition from loose particle-film to compact particle shell upon introduction of salt was found, as predicted theoretically for charged particles adsorbed on interfaces. Particulate interfacial films built by SFMMT nanoparticles protected DDSA droplets from aggregation and formed a honeycomb structure. Salt in the DDSA emulsification process restrained the hydrolytic action of DDSA effectively and sustained the sizing performance of DDSA even 5 h after the emulsion preparation.
  • Researchpp 2773-2782Pu, G., Zhu, W., Zhou, H., Liu, Y., and Zhang, Z. (2015). "Kinetics of co-gasification of low-quality lean coal and biomass," BioRes. 10(2), 2773-2782.AbstractPDF
    The co-gasification behaviors of composite samples of biomass and lean coal were invest­igated under a CO2 atmosphere. The composite behaviors were determined based on thermogravimetric analysis and the Coats-Redfern method. These methods were used to analy­ze the kinetics of the processes. The results showed that the temperature ranges of the lean coal, biomasses, and the gasification ability of each biomass were different, and the coordination effects of each biomass varied. The addition of alkali metals had little influence on the pyrolysis efficiency and the peak temperature of composite samples of soybean stalk and lean coal, but it did promote gasification. In the pro­cesses of pyrolysis and gasification, composite samples of soybean stalk and lean coal exhibited lower activation energies than unmixed samples, but there was no significant enhancement with the extra alkali metal.
  • Researchpp 2783-2796Xiang, L. Y., Hanipah, S. H., P. Mohammed, M. A., Samsu Baharuddin, A. S., and Lazim, A. M. (2015). "Microstructural, mechanical, and physicochemical behaviours of alkali pre-treated oil palm stalk fibers," BioRes. 10(2), 2783-2796.AbstractPDF
    The effect of alkali pre-treatment (sodium hydroxide, NaOH) on the microstructural, mechanical, and chemical composition of oil palm stalk fibres (OPSF) is reported for future bioconversion processes. The OPSF was pre-treated with various concentrations of NaOH (5, 10, 20, 30, and 40% w/v). Scanning electron microscopy analysis revealed that 5% w/v alkali concentration caused complete removal of silica bodies and waxy layers, whereas pronounced degradation of the fibres occurred at 40% w/v NaOH concentration. Mechanical test results showed that the maximum elastic modulus of untreated OPSF was 2.5 GPa and the modulus was not sensitive to alkali concentration. Permanent set (plastic strain) and viscoelastic behaviours of OPSF were observed from the loading-unloading and stress relaxation test results, respectively. Agreement was observed between the Prony series viscoelastic model and test results, which provided further evidence of the viscoelastic behaviour of OPSF.
  • Researchpp 2797-2808Chen, Q., Endo, T., and Wang, Q. (2015). "Characterization of bamboo after ionic liquid-H2O pretreatment for the pyrolysis process," BioRes. 10(2), 2797-2808.AbstractPDF
    Bamboo (Phyllostachys edulis) samples pretreated with ionic liquid (ILs)-H2O mixtures were studied concerning their application in the pyrolysis process. [Bmim]Cl-H2O, [Bmim]BF4-H2O, [Bmim]HSO4-H2O, and [Bmim]Ac-H2O mixture systems were used in the pretreatment process. The characteristics of pretreated bamboo were analyzed, as was cellulose extracted from ILs-H2O pretreated bamboo. The enrichment of cellulose (α-cellulose) in pretreated bamboo was achieved. The amount of char resulting from the pyrolysis of the [Bmim]Ac-H2O pretreated sample (20.1 wt%) was lower than the untreated bamboo sample (24.2 wt%) at 900 °C. A greater proportion of the pretreated bamboo samples was converted into gas products and/or liquids. The pretreated cellulose pyrolysis process could proceed more easily than processing untreated samples due to the disordered crystalline cellulose structure and the decrease in molecular weight.
  • Researchpp 2809-2822Xu, C., Wang, G., Xing, C., Matuana, L. M., and Zhou, H. (2015). "Effect of graphene oxide treatment on the properties of cellulose nanofibril films made of banana petiole fibers," BioRes. 10(2), 2809-2822.AbstractPDF
    In this study, banana petiole-based cellulose nanofibril (CNF) films treated with graphene oxide (GO) were prepared and evaluated by means of Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). Tensile strengths (TS), dynamic mechanical properties, and thermal stabilities of the films were affected positively when the GO loading was less than 4.4 wt%. From these results, FTIR spectra, and SEM analyses, a strong coupling between the GO and the cellulose matrix could be concluded at lower GO loadings. The TGA and DMA results also suggested that the CNF film treated with 4.4 wt% GO had more char residue, better thermal stability, higher storage modulus, and higher retention ratio when compared to that without treatment. This work provides a new approach for more effective utilization of banana petiole as a feedstock for CNF and GO/CNF composites.
  • Researchpp 2823-2835Ogunsanwo, O. Y., Terziev, N., Panov, D., and Daniel, G. (2015). "Bamboo (Bambusa vulgaris Schrad.) from moist forest and derived savanna locations in South West Nigeria - properties and gluability," BioRes. 10(2), 2823-2835.AbstractPDF
    Bamboo culms of Bambusa vulgaris Schrad. were collected from two locations in moist forests and two sites in derived Savanna zones in South West Nigeria. The study involved chemical analyses, density variability, bonding tests, gluability tests, and measurements of bending strength of the bamboo in addition to durability testing with decay fungi and treatability of glued boards with a copper-based wood preservative. Chemical analyses showed a uniform composition of the bamboo with a cellulose content of 45 to 47.5% and a lignin content of 23 to 25.6% as the predominant chemical constituents. An average wood density of 700 kg/m3 was a prerequisite for high mechanical strength. The moduli of elasticity were high and exceeded 14 kN/mm2 for bamboo boards and 13 kN/mm2 for finger joints. Bamboo boards from all growth sites showed high moduli of rupture in the range of 150 to 166 N/mm2 and 72.9 to 94.7 N/mm2 for boards and finger joints, respectively. Bamboo from the four sites showed variable mass loss with the EN-113 (1996) test method, which classifies this biomass as a moderately to non-durable plant material. White rot fungus (Trametes versicolor) caused the highest mass losses (11.2 to 16.8%). The bamboo showed good treatability using a 500-kg/m3 solution of a copper-based preservative.
  • Researchpp 2836-2849Han, X., Chu, L., Liu, S., Chen, T., Ding, C., Yan, J., Cui, L., and Quan, G. (2015). "Removal of methylene blue from aqueous solution using porous biochar obtained by KOH activation of peanut shell biochar," BioRes. 10(2), 2836-2849.AbstractPDF
    Biochar from peanut shell was used as the precursor for the preparation of porous biochar by KOH activation. The pore structures of porous biochar also were characterized by scanning electron microscopy (SEM) and N2 adsorption/desorption. The adsorption performance for the removal of methylene blue (MB) was deeply investigated. The effects of impregnation ratio (KOH/biochar: w/w), activation temperature, and activation time on the removal of methylene blue by porous biochar were evaluated. In addition, the effects of initial MB concentration and pH value on the adsorption process were also studied. The optimum conditions for preparing porous biochar were obtained with 1.5:1 of impregnation ratio, 800 °C of activation temperature, and 90 min of the holding time in activation. Results indicated that the adsorption capacity was high even at higher initial MB concentrations. The adsorption process followed pseudo-second-order kinetics. The experimental adsorption isotherm was found to be best fitted with the Langmuir model, which implying that the adsorption of MB by porous biochar proceeded as a monolayer adsorption, and the maximum monolayer adsorption capacity of MB was 208 mg∙g-1.
  • Researchpp 2850-2858Gençer, A., and Şahin, M. (2015). "Identifying the conditions required for the NaOH method for producing pulp and paper from sorghum grown in Turkey," BioRes. 10(2), 2850-2858.AbstractPDF
    This study examines the possibilities of making pulp from sorghum grown in Bartın via the NaOH method. While setting the cooking conditions for producing pulp from annual plants, NaOH was used in quantities that amounted to 14, 16, 18, and 20% of the total weight of the dry sample. Optimum conditions were established relative to pulp yield, Kappa number, and a scoring table based on mechanical, optical, and physical values. Accordingly, optimum conditions for pulp production from sorghum stalks occurred when 20% NaOH was used at 120 °C, a 5:1 solution-to-stalk ratio, and a cooking time of 60 min.
  • Researchpp 2859-2872Hasfalina, C. B. M., Akinbile, C. O., and Jun, C. X. (2015). "Coconut husk adsorbent for the removal of methylene blue dye from wastewater," BioRes. 10(2), 2859-2872.AbstractPDF
    A study to assess the efficiency of coconut husks (CHs) in removing methylene blue (MB) dye from wastewaters in Malaysia was carried out. A fixed bed column adsorber was set up using flow rates of 40 and 80 mL/min, and the adsorbent (CH) was prepared using the base treatment method with NaOH as activating agent. Three different column bed depths (10, 20, and 25 cm) and unit weights of adsorbent (103, 213, and 260 g) were used. Two models, the bed depth service time (BDST) and Thomas models, were used to validate the adsorption capacity results and breakthrough curve. Changing the bed depth from 20 to 25 cm did not result in a significant change in adsorption capacity, therefore a 20-cm bed depth is recommended as the most efficient. Similarly, adsorption capacity increased as flow rates increased from 40 to 80 mL/min, indicating that a flow rate of 80 mL/min yielded optimum efficiency. The two models also provided predictions with good fits of the bed depth effect, the adsorption capacity, and the breakthrough curve of CH for MB removal.
  • Researchpp 2873-2887Kminiak, R., and Gaff, M., (2015). "Roughness of surface created by transversal sawing of spruce, beech, and oak wood," BioRes. 10(2), 2873-2887.AbstractPDF
    The created surface irregularities, namely roughness profile Ra, after the sawing of spruce, beech, and oak wood on a sliding mitre saw with manual saw blade feeding were studied. The created surface roughness was monitored at a cut height, e, of 50 mm using three basic modes of solid wood transversal sawing (flatwise cross-cutting at φ2=90°, flatwise edge-mitre cross-cutting, and flatwise mitre cross-cutting at φ2=45°). The monitored surface was made using a sliding mitre saw with the gradual application of saw blades with 24, 40, or 60 teeth, and special saw blade with 24 teeth and a chip limiter (CL), respectively. The saw blades used had identical angle geometries. Three levels of feed force, Fp, of 15, 20, and 25 N corresponding to a range of feed forces used by different operators were used in the experiment. The roughness of sawn surfaces was significantly influenced by cutting model, wood species, type of saw blade, and feed force. The created surface roughness values were very close to the plane milling values.
  • Researchpp 2888-2902Ma, Z., Ye, J., Zhao, C., and Zhang, Q. (2015). "Gasification of rice husk in a downdraft gasifier: The effect of equivalence ratio on the gasification performance, properties, and utilization analysis of byproducts of char and tar," BioRes. 10(2), 2888-2902.AbstractPDF
    Rice husks (RH) are a potential biomass source for bio-energy production in China, such as bio-gas production by gasification technology. In this paper, a bench-scale downdraft fixed bed gasifier (DFBG) and a tar sampling system were designed. The effect of equivalence ratio (ER) on gasification performance in terms of the temperature in the gasifier, the composition distribution of the producer gas, and the tar content in the producer gas was studied. The maximum lower heating value of 4.44 MJ/Nm3, minimum tar content of 1.34 g/Nm3, and maximum cold gas efficiency of 50.85% were obtained at ER of 0.211. In addition, the characteristics of gasification byproducts, namely bio-char and bio-tar, were analyzed. The proximate and ultimate analysis (especially of the alkali metal), the surface morphology, the surface area, and the pore size distribution of the rice husk char (RHC) were obtained by the use of X-ray fluorescence (XRF) and scanning electron microscopy (SEM), as well as by using the Brunauer-Emmett-Teller (BET) method. The components of light tar and heavy tar were obtained by using gas chromatography-mass spectrometry (GC-MS).
  • Researchpp 2903-2912Niu, M., Wang, X., Hagman, O., Karlsson, O., and Xie, Y. (2015). "Microstructure of burned ultra-low-density fiberboards using plant fiber as the matrix and Si-Al compounds as the filler," BioRes. 10(2), 2903-2912.AbstractPDF
    Ultra-low-density fiberboards (ULDFs) were prepared by a liquid frothing technique using plant fibers as the matrix and Si-Al compounds as the filler to be used as a versatile bio-based composite. Si-Al compounds played an important role in the fire properties of ULDFs. Fire intensity and the amount of volatiles were significantly restrained because of the Si-Al compounds. To determine the combustion mechanism of ULDFs treated by Si-Al compounds, the microstructure of burned specimens was tested by chemical analysis, X-ray diffractometer (XRD), and infrared spectrometer (IR). According to the results from gas chromatography, glucose, xylose, and mannose disappeared in the bottom ashes. After combustion, the XRD profiles of the two ashes became weaker and broader; the sharpest peaks at 18.6° (2q) that represented Si-Al compounds remained; the obvious peaks at 22° (2q) from cellulose were gone. The results from IR suggested the characteristic functional groups OH, CH, and C=O from carbohydrate also disappeared, and absorbance at 1200 to 400 cm-1, which attributed to the vibration of Si-O, Al-O, and Si-O-Si bonds, increased. In conclusion, fibers are almost completely pyrolyzed at 780 °C. The crystalline structure of Si-Al compounds is rearranged and more amorphous silicon oxide and aluminum oxide are generated.
  • Researchpp 2913-2925Zhao, Y.-M., Liu, Z., Hui, L.-F., Li, Q., Li, X.-S., and Huang, Y.-J. (2015). "Degumming pretreatment with sodium hydroxide and sodium oxalate in the process of whole cotton stalk APMP pulping," BioRes. 10(2), 2913-2925.AbstractPDF
    The effect of degumming pretreatment on whole cotton stalk alkaline peroxide mechanical pulp (APMP) was researched. Degumming pretreatment was used as the first stage of an APMP pulping process, replacing conventional hot water pretreatment. Two degumming agents of sodium hydroxide (NaOH) and sodium oxalate (Na2C2O4) were researched separately. The efficiency of hot water pretreatment, NaOH pretreatment, and Na2C2O4 pretreatment on pectin and metal ions removal was compared. After pretreatment of hot water, NaOH, and Na2C2O4, pectin content was reduced to 4.0%, 2.1%, 1.6%, respectively, compared to original material (4.3%), at removal rates of 7%, 51%, and 64%, respectively. For metal ions, especially transition metal ions, the removal rate was up to 20% after degumming pretreatment. The brightness of the handsheets was 64% ISO, 68% ISO, and 73% ISO, respectively. The dirt count was 2674 mm2·m-2, 533 mm2·m-2, and 132 mm2·m-2, respectively. After Na2C2O4 pretreatment, the tension index and tear index were increased to 40.5 N·m·g-1 and 4.5 mN·m2·g-1, respectively. Through degumming pretreatment, pectin, metal ions, and dirt count were reduced efficiently, and the brightness and physical strength were improved significantly.
  • Researchpp 2926-2935Zhong, Y., Zhou, H., and Wen, L. (2015). "The effect of elevated temperature on bending properties of normal wood inside Chinese larch wood during fire events," BioRes. 10(2), 2926-2935.AbstractPDF
    Timber is used extensively in construction. Therefore, it is important to characterize the response of wood when exposed to elevated temperatures for a sustained period of time. In fire-resistant designs for timber structures, the main goal is to assess in-fire and post-fire structural integrity. The objectives of this study were to study the immediate effect and the residual effect of temperature on bending properties for Chinese larch (Larix gmelinii). A total of 72 specimens were subjected to a static 3-point bending test at various temperatures. The results indicated that both the bending strength (BS) and modulus of elasticity (MOE) decreased nonlinearly as the temperature was increased from 20 to 225 °C for the immediate effect test. For the residual effect test, both the BS and MOE first increased non-linearly and then decreased with increasing temperature. There were significant differences between the immediate effect test and the residual effect test for both BS and MOE. The bending properties in the residual effect test were larger than those in the immediate effect test.
  • Researchpp 2936-2948Zhong, L., Ding, Z., Li, B., and Zhang, L. (2015). "Preparation and characterization of polysulfone/sulfonated polysulfone/cellulose nanofibers ternary blend membranes," BioRes. 10(2), 2936-2948.AbstractPDF
    Ternary blend membranes were prepared with polysulfone (PSf), sulfonated polysulfone (SPSf), and cellulose nanofibers (CNF) by a Loeb-Sourirajan (L-S) phase inversion process. The cross-section and bottom surface morphology of the membranes were analyzed by scanning electron microscopy (SEM), and the performance of the membranes was evaluated in terms of pure water flux, bovine serum albumin (BSA) rejection, contact angle, tensile strength, and breaking elongation. The morphology of the cellulose nanofibers (CNF) was detected by transmission electron microscopy (TEM). Results showed that within a certain range, the addition of SPSf improved compatibility between PSf and CNF, and the addition of CNF could improve the hydrophilicity of the membranes. The maximum value of pure water flux reached 137.6 L/m2h, and the minimum value of BSA rejection reached 95.8% when CNF content was 0.3 wt% in casting solution. Also, a certain addition of CNF could enhance the mechanical properties of the membranes.
  • Researchpp 2949-2968Then, Y. Y., Ibrahim, N. A., Zainuddin, N., Ariffin, H., Chieng, B. W., and Wan Yunus, W. M. Z. (2015). "Influence of fiber content on properties of oil palm mesocarp fiber/poly(butylene succinate) biocomposites," BioRes. 10(2), 2949-2968.AbstractPDF
    Biodegradable and environmentally friendly biocomposites produced by a combination of biodegradable thermoplastics and natural fiber have gained increasing interest in recent years. In this work, eco-friendly biocomposites made from poly(butylene succinate) (PBS) and different weight percentages (10, 30, 50, and 70 wt%) of oil palm mesocarp fiber (OPMF) were fabricated via a melt blending process followed by hot-press molding. The biocomposites showed an improvement in storage and loss moduli with increasing fiber content, as indicated by dynamic mechanical analysis. Also, the water uptake and thickness swelling of the biocomposites increased with fiber content. The presence of fiber improved the biodegradability of the PBS, as evidenced from soil decomposition and scanning electron microscopy studies. Conversely, the presence of fiber lowered the melting and crystallization temperature as well as the thermal stability of neat PBS. The biocomposites from PBS and OPMF could be promising biocomposite materials because of their improved mechanical properties and biodegradability compared to neat PBS.
  • Researchpp 2969-2981He, W., Zhang, X., Yu, C., Huang, D., and Li, Y. (2015). "Synthesis of bamboo/polyaniline composites by in situ polymerization and their characteristics," BioRes. 10(2), 2969-2981.AbstractPDF
    Intrinsically conductive bamboo products were polymerized by the impregnation of an aniline monomer solution into a bamboo substrate and the in situ polymerization of PANI to obtain a semi-conducting material; the bamboo products thus obtained combined characteristics of conductivity of the PANI polymer and the strength of natural bamboo. Light microscopy and scanning electronic microscopy images showed that PANI was uniformly dispersed within the cell lumen and cell wall of the bamboo substrate. The weight percent gain and volume bulk increase of the modified bamboo were 5.18 and 14.9%, respectively. Equilibrium uptake studies showed that the modified bamboo was less hydrophilic, caused by the addition of hydrophobic PANI. The electrical conductivity of the bamboo/PANI composite ranged from 3 × 10-4 to 1 × 10-3 S cm-1, which was tuned by changing the phosphate acid concentration. Fourier transform infrared spectra revealed that PANI was closely polymerized onto the cell wall, allowed by the accessibility of the amine groups of the aniline monomer to the hydroxyl groups of the bamboo matrix. Furthermore, X-ray diffraction analysis indicated that after the in situ polymerization of PANI, the bamboo cellulose maintained a classic cellulose structure, while its degree of crystallinity was decreased.
  • Researchpp 2982-2994Jiang, X., Han, J., Han, Q., Zhou, X., and Ma, J. (2015). "Preparation and characteristics of paper-based biodegradable plastics," BioRes. 10(2), 2982-2994.AbstractPDF

    The aim of this work was to make biodegradable plastics from renewable resources. Paper-based biodegradable plastics were produced via a sol-gel process by using zinc chloride solution. The optimum conditions were a zinc chloride concentration of 65%, reaction temperature of 70 °C, reaction time of 5 s, aging time of 3 h, and glycerol concentration of 10%. Fourier transform infrared spectroscopy (FT-IR) and wide-angle X-ray diffraction (XRD) revealed that no chemical reaction occurred and the crystal form of the cellulose remained cellulose I, but the degree of crystallinity decreased. Compared to other biodegradable plastics, these paper-based biodegradable plastics had better mechanical properties and greater biodegradability.

  • Researchpp 2995-3004Li, Z., Yang, R., Yang, F., Zhang, M., and Wang, B. (2015). "Structure and properties of chitin whisker reinforced papers for food packaging application," BioRes. 10(2), 2995-3004.AbstractPDF
    In recent years, concerns about environmental waste caused by petroleum-derived chemicals as well as the consumer's demand for high quality food products, have prompted people to pay more attention to developing biodegradable food packaging materials using natural resources such as cellulose fibers and chitin derivatives. In this study, chitin whiskers have been successfully generated by hydrolyzing the α-chitin sample. Then the synthesized nano-sized chitin whiskers were used at ratios from 0.1% to 2% (wt%) for improving strength properties of paper sheets by the dip-coating method. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM) were used to investigate the morphology of chitin whiskers and cellulose fiber compounds. The results showed that coating with chitin whiskers brought about an increase in tear strength, burst strength, and wet and dry tensile strength, with a decrease in Zeta-potential value.
  • Researchpp 3005-3016Chen, H., Fu, Y., Wang, Z., and Qin, M. (2015). "Degradation and redeposition of the chemical components of aspen wood during hot water extraction," BioRes. 10(2), 3005-3016.AbstractPDF
    Hot water extraction (HWE) prior to pulping of wood is a promising method in constructing a platform for traditional pulping or for biorefinery processing. In this study, HWE of aspen wood at a maximum reaction temperature (Treaction) between 140 and 180 ºC was investigated to obtain an optimal extraction condition for wood-derived products. The effect of extraction temperature and reaction time on the extraction performance of the chemical constituents was evaluated, and the degradation and redeposition of lignin and carbohydrates during the HWE process were assessed. Results showed that a minimum Treaction of 160 ºC was necessary for satisfactory carbohydrate removal. The dissolution and readsorption of sugars reached a balance, such that no more sugars in pre-extraction liquor (PEL) were adsorbed on the wood surface under more severe extraction conditions. The reduction of sugars dissolved in PEL should result from the formation of furfural or its derivatives. At the final extraction stage, the dissolved lignin in PEL could redeposit on the exothecium rather than the endothecium of the wood chips.
  • Researchpp 3017-3026Zhang, Y., Zhai, M., Wang, X., Sun, J., Dong, P., Liu, P., and Zhu, Q. (2015). "Preparation and characteristics of biomass char," BioRes. 10(2), 3017-3026.AbstractPDF
    Rice husk and sawdust were selected as the raw materials for a study of biomass char yield in the range of 600 to 900 °C. It was found that temperature was the primary factor affecting the biomass char yield. The yield of the rice husk and sawdust chars decreased significantly with increasing temperature. As the residence time increased, the biomass char yield decreased. The smaller the size of the biomass particles, the higher the char yield. When the temperature exceeded 800 °C, the difference in the char yield was only slight. Given this finding, the surface morphologies of rice husk, sawdust, and their respective chars were investigated under various conditions via scanning electron microscopy. The effects of temperature on the pore structures were investigated by the Accelerated Surface Area and Porosimetry System. There were more holes in the biomass char, and the specific surface area was increased significantly as the temperature increased. The specific surface areas of rice husk and sawdust chars prepared at 900 °C were 320 and 1140 m2/g, respectively.
  • Researchpp 3027-3044Li, W., and Wang, C. (2015). "Biodegradation of gallic acid to prepare pyrogallol by Enterobacter aerogenes through substrate induction," BioRes. 10(2), 3027-3044.AbstractPDF
    Pyrogallol, as an important chemical raw material and reagent, has been prepared by the decarboxylation reaction of gallic acid hydrolyzing tannin acid extracted from Chinese gall, but the decarboxylation reaction is known to cause serious environmental pollution. To obtain efficient strains to degrade gallic acid, a screening study was carried out to explore different strains and optimal fermentation conditions of single impact factors, as well as using response surface methodology. The antioxidant bioactivity of products containing pyrogallol in the fermentation medium was also estimated. The results indicated that Enterobacter aerogenes could degrade gallic acid into pyrogallol with 77.86% average yield under the optimal fermentation conditions of an inoculum size of 5%, substrate concentration of 0.32%, incubation period of 60 h, fermentation temperature of 32 °C, content of phosphate buffer at 25%, and an initial pH of 6.0 in fermentation medium. The products contained 66.5% pyrogallol and were tested for their antioxidant capacity. They proved to have stronger antioxidant capacity compared with ABTS, BHT, and even Vc. In conclusion, the study provided a simple, highly efficient method, superior to complex genetic engineering technologies, to degrade gallic acid into pyrogallol, suggesting the possibility of large-scale production in the future.
  • Researchpp 3045-3055Claramunt, J., Ardanuy, M., and Fernandez-Carrasco, L. J. (2015). "Wet/dry cycling durability of cement mortar composites reinforced with micro- and nanoscale cellulose pulps," BioRes. 10(2), 3045-3055.AbstractPDF
    A combination of reinforcements at different levels can have a synergetic effect on the final properties of a composite. The aim of this work was to produce, evaluate, and compare the wet/dry cycling durability of the exposure of cement composites reinforced with conventional pulps at the micro-scale level, with nanofibrillated cellulose fibers at the nano-scale level, and with combinations of both reinforcements (hybrid composites). To evaluate the durability of their mechanical properties, the composites were tested under flexural loading after 28 days of humidity chamber curing and after 20 wet/dry accelerating aging cycles. Composites reinforced with the nanofibrillated cellulose exhibited significantly higher flexural strength and flexural modulus, but they had lower fracture energy values than those reinforced with conventional sisal fibers. Moreover, the hybrid composites with a high content of nanofibrillated cellulose maintained or even improved their properties after aging.
  • Researchpp 3056-3069Börjesson, M., Richardson, G., and Westman, G. (2015). "UV radiation of cellulose fibers and acrylic acid modified cellulose fibers for improved stiffness in paper," BioRes. 10(2), 3056-3069.AbstractPDF
    In this study, the strength and stiffness was measured on paper sheets with and without acryl ester functionalization grafted with UV-reactive molecules. Three different monomers with one, two, and three UV-reactive groups, respectively, were reacted with the unsaturated ester. The tri-functional monomer had the most influence on the strength properties of the three monomers and was added in concentrations of 5 to 20 wt% of paper (0.03-0.11 mol eq./AGU). The strength and stiffness properties were measured with tensile tests. An increase in elongation, tensile index, and Young’s modulus was seen after irradiation. However, the paper sheets esterified with acrylic acid prior to radiation showed no improvement in stiffness compared to a non-treated paper. As a result, the esterification with acrylic acid to enhance the grafting effect did not have the ability to compensate for the loss in strength caused by the esterification treatment.
  • Researchpp 3070-3078Zhang, H., Hunt, J. F., and Zhou, L. (2015). "Comparison of wood composite properties using cantilever-beam bending," BioRes. 10(2), 3070-3078.AbstractPDF
    Wood-based composite panels generally are first tested out-of-plane in the primary panel direction followed by the cross panel direction, but rarely edgewise. While most applications use wood-based composites in the flat-wise orientation and only need the out-of-plane properties, there are construction configurations where edgewise properties are needed for improved design configurations. A square cantilever beam was used to determine the apparent stiffness (EI) and modulus of elasticity (E) differences for 3 wood-based composite panel materials. Specimens were cut along the primary panel direction or machine direction (MD) and perpendicular to the primary direction or cross-machine direction (CD). The square specimens were first non-destructively tested oriented in the normal or out-of-plane position, then rotated 90 degrees to measure edgewise properties. The results for a 20 mm thick medium density fiberboard (MDF) showed that the MD properties were 56% higher than the CD properties. The other two composite materials, 12 mm thick particleboard (PB) and 12 mm thick MDF, were essentially the same in the MD or CD directions. For all the materials, the differences between the out-of-plane and the edgewise loading directions showed higher EI and E between 17 to 61%, respectively. The largest difference was found in the PB composite material properties that were between 42 to 61% higher for the out-of-plane properties. For the 12 and 20 mm thick MDF material, in-plane properties were 27 to 33% and 17 to 23% higher, respectively. The cantilever bending method was able to quickly assess the difference using the same specimen.
  • Researchpp 3079-3096Vilakati, G. D., Hoek, E. M. V., and Mamba, B. B. (2015). "Investigating the usability of alkali lignin as an additive in polysulfone ultrafiltration membranes," BioRes. 10(2), 3079-3096.AbstractPDF
    The effects of natural and synthetic polymer additives on the properties of ultrafiltration membranes were studied. The use of NaOH to remove the residual additive remaining in the membranes during coagulation was also investigated, as was the effect of NaOH post-treatment relative to membrane performance. To evaluate the residual additives present, ATR-FTIR was used. Contact-angle analysis and water-absorption experiments were used to examine the hydrophilic properties of the prepared membranes. Membranes modified with lignin (Lig) were found to absorb more water (94% water uptake) than other membranes. In general, the contact angles were found to be low for membranes treated with NaOH. Membrane permeability was greatest in lignin_polysulfone (Lig_PSf), followed by polyvinylpyrrolidone_polysulfone (PVP_PSf), and with polyethylene glycol_polysulfone (PEG_PSf) the least permeable, similar to the trend observed in water uptake. A ‘Robeson plot’ analogue showed that Lig_PSf membranes had high separation factors regardless of the size of the solute being rejected. This study indicates the feasibility of using cheap, readily available additives to increase the performance of membranes.
  • Researchpp 3097-3111Pelit, H., Sönmez, A., and Budakçı, M. (2015). "Effects of thermomechanical densification and heat treatment on density and Brinell hardness of Scots pine (Pinus sylvestris L.) and Eastern beech (Fagus orientalis L.)," BioRes. 10(2), 3097-3111.AbstractPDF
    The effects of thermomechanical densification (TMD) and heat treatment on density and Brinell hardness of Scots pine (Pinus sylvestris L.) and Eastern beech (Fagus orientalis L.) woods were investigated. Samples were densified using a specially designed hydraulic press with target compression ratios of 20 and 40%, and at 110 °C and 150 °C. Then, the heat treatment was applied to the samples at three different temperatures. To determine whether the changes occurred because of technological properties, tests of Brinell hardness and air-dry density were conducted. Increases of 42 and 35% were obtained for the density of Scots pine and beech samples, respectively. After the densification process, increases in radial and tangential hardness values were obtained. Decreases were observed in the density and hardness values of the samples because of the increase in temperature during heat treatment. After heat treatment, there were 4 and 5% decreases in the respective densities of Scots pine and beech, and decreases in their radial and tangential hardness values.
  • Researchpp 3112-3130Abdel-Halim, E. S., and Al-Hoqbani , A. A. (2015). "Utilization of poly(acrylic acid)/cellulose graft copolymer for dye and heavy metal removal," BioRes. 10(2), 3112-3130.AbstractPDF
    A cellulosic component was extracted from low-value palm tree wastes, empty fruit bunches, and functionalized through grafting with acrylic acid in a previous study. The as-synthesized poly(acrylic acid)/cellulose graft copolymer was applied in the current study as an adsorbent for the removal of the cationic dye methylene blue and the heavy metal lead from industrial wastewater. Factors and parameters that govern the adsorption process were studied during the experimental portion of this study. These factors included the effect of agitation duration, adsorbate medium pH, adsorbent dose, adsorbent graft yield, and initial adsorbate concentration on the efficiency of the said adsorption processes. The data obtained from the adsorption of either methylene blue or lead ions onto the graft copolymer were well fitted to both Langmuir and Freundlich adsorption models.
  • Researchpp 3131-3145Hunt, J. F., Zhang, H., and Huang, Y. (2015). "Analysis of cantilever-beam bending stress relaxation properties of thin wood composites," BioRes. 10(2), 3131-3145.AbstractPDF
    An equivalent strain method was used to analyze and determine material relaxation properties for specimens from particleboard, high density fiberboard, and medium density fiberboard. Cantilever beams were clamped and then deflected to 11 m and held for either 2 h or 3 h, while the load to maintain that deflection was measured vs. time. Plots of load relaxation for each specimen showed similar load relaxation vs. time even though there were some slight differences in the maximum load per sample. Three models were developed to fit the relaxation data. The first model was a simple log decrement. This simple log model used only one variable, the relaxation coefficient, to describe the relaxation behavior as the log of time. The log decrement model was marginal at best in modeling the relaxation data. The second and third models, however, used equivalent strain methods. The second model assumed a combined linear-elastic spring and a Kelvin-Voigt spring-dashpot model. The third model used a combination of a linear-elastic spring (linear strain) element, a Kelvin-Voigt (spring-dashpot, visco-elastic strain) element, and a dashpot (permanent strain) element for its total configuration. Both equivalent strain models provided excellent correlations for the two lengths of time used for this series. Estimated mechanical and relaxation, or creep properties, were determined from the equivalent strain method using cantilever beam equations.
  • Researchpp 3146-3153Dai, X., Qian, S., Ren, H., and Omori, S. (2015). "Characterization and application of bamboo (Sinocalamus affinis) lignophenols in lignophenols-pulp sheet composites," BioRes. 10(2), 3146-3153.AbstractPDF
    Bamboo (Sinocalamus affinis) lignophenols (Lps), synthesized using a phase separation system, were used as a natural plasticizing additive to complex with pulp (short fiber and fluffy short fiber) sheets. The structural features of Lps were analyzed by gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectroscopy, and proton-nuclear magnetic resonance (1H-NMR). The pulp sheet absorptivity of Lps, as well as the physical properties of complex sheets, were discussed. Results showed that when the concentration of bamboo Lps solution was 10 g/L, the absorption amount of Lps in the sheets made up of short pulp fibers (12%) was slightly higher than that of sheets made of fluffy short pulp fibers (10%), whilephysical properties, such as tightness, tensile strength, elongation, bursting, and tearing, were improved obviously after the addition of Lps. More obvious improvement in the physical strength was found in sheets made up of fluffy short pulp fibers. Results indicated that the amount of absorbed Lps was of the same importance as the properties of the pulp fibers. It is necessary to adjust the properties of both the Lps and sheets to get the best mechanical strength for the pulp sheets.
  • Researchpp 3154-3168Boondaeng, A., Vaithanomsat, P., Apiwatanapiwat, W., Trakunjae, C., and Kongtud, W. (2015). "Statistical approach for optimization of ethanol production from fast-growing trees: Acacia mangium and Acacia hybrid," BioRes. 10(2), 3154-3168.AbstractPDF
    This is the first report of the potential of Acacia fast growing trees in Thailand, A. mangium and the Acacia hybrid (A. mangium x A. auriculiformis), as raw material for ethanol production through a simultaneous saccharification and fermentation process by Saccharomyces cerevisiae TISTR 5339. Alkaline pulping was applied as the pretreatment process. Optimization of ethanol production was studied using response surface methodology based on central composite design. The optimized conditions of 100 g/L solid loading and an A600 of S. cerevisiae TISTR 5339 of 2 gave observed values of ethanol production of 35.7 and 27.3 g/L, which corresponded with the predicted values of 32.32 and 26.37g/L from A. mangium and A. hybrid, respectively. This condition was then used for up-scaling in a 10-L stirred bioreactor. The improved maximum ethanol concentrations of 37.84 and 36.52 g/L were obtained from A. mangium and Acacia hybrid, respectively, within 96 h of cultivation at 30 °C and no aeration rate.
  • Researchpp 3169-3180Qian, S., Dai, X., Qi, Y., and Ren, H. (2015). "Preparation and characterization of polyhydroxybutyrate-bamboo lignophenol biocomposite films," BioRes. 10(2), 3169-3180.AbstractPDF
    Four kinds of lignophenols (Lps) were derived from native bamboo (Sinocalamus affinis) lignin through phase separation system by using four kinds of phenols (p-cresol, catechol, resorcinol and pyrogallol) as derivatives and 72% concentrated sulfuric acid as catalyst. The resulting lignophenols were characterized by 1H-NMR, FT-IR, and GPC analysis. Then they were blended with polyhydroxybutyrate (PHB) to cast thin biocomposite films. The mechanical properties, water-absorbing qualities, and thermal properties of films were tested and discussed. The results indicated that phase separation treatment can effectively improve phenolic hydroxyl contents of lignins. The lignin macromolecule was significantly reduced to small size and well-soluble polymers. The best amounts of added Lps in composite films depended upon the kind of phenols. In present study, the mechanical properties, water-absorbing qualities, and thermal properties of biocomposite films showed good results at less than 10% Lps’ addition. This provides a possibility that a new kind of biodegradable films can be made up of engineering plastics and lignin.
  • Researchpp 3181-3196Li, L., Hu, Y., and Cheng, F. (2015). "Butyration of lignosulfonate with butyric anhydride in the presence of choline chloride," BioRes. 10(2), 3181-3196.AbstractPDF
    A novel process was developed for the butyration of lignosulfonate (LS) with butyric anhydride in the presence of choline chloride at elevated temperatures. The degree of substitution (DS) was qualitatively and quantitatively determined byFourier transform infrared spectroscopy using the baseline method. It was found that the DS of butyrated LS products increased from 0 to the range of 0.41 to 2.14 with the addition of choline chloride, indicating that butyric anhydride-choline chloride is a novel and highly effective solvent for the butyration of LS. The DS of butyrated LS was dependent on choline chloride dosage, reaction temperature, reaction time, and the mass ratio of butyric anhydride to LS. Characterization results by proton nuclear magnetic resonance spectroscopy further demonstrated the occurrence of the butyration reaction. The results of thermogravimetric analysis showed that the thermal stability of the butyrated LS decreased with increasing degree of substitution.
  • Researchpp 3197-3209Furlan de Jesus, J. P., Sain, M., Jeng, R., Negrão, D. R., Leão, A. L., de Andrade, M. C. N., and Minhoni, M. T. A. (2015). "Potential application of Ganoderma lucidum in solid state fermentation of primary sludge and wheat straw," BioRes. 10(2), 3197-3209.AbstractPDF
    This study was conducted to investigate the production of lignocellulolytic enzymes and sugars by the fungus Ganoderma lucidum during solid state fermentation (SSF) using primary sludge (PS) and wheat straw (WS) as substrates at different concentration ratios. For fungal growth on SSF, 20 g of each blended substrate was added to Erlenmeyer flasks, which were autoclaved and maintained at room temperature prior to inoculation, whereas for submerged fermentation (SF), flasks containing 25 mL of potato dextrose broth (PDB) were used as standard to check the differences between both methods of growth, and then all flasks were incubated at 25 °C in the dark, during 8 and 16 days. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis from the protein extract obtained from solid state fermentation strongly suggested that G. lucidum could produce lignocellulolytic enzymes to degrade primary sludge and wheat straw. Among the sugars, the production of xylose and mannose was disturbed by adding primary sludge. With the addition of primary sludge, high glucuronic acid content was observed. The results suggest that the combination of primary sludge and wheat straw, at concentration ratios of 1:1 to 1:3, respectively, can be used as a raw material in the production of lignocellulolytic enzymes and the bioconversion of other types of biomass by G. lucidum.
  • Researchpp 3210-3223Dicke, C., Lühr, C., Ellerbrock, R., Mumme, J., and Kern, J. (2015). "Effect of hydrothermally carbonized hemp dust on the soil emissions of CO2 and N2O," BioRes. 10(2), 3210-3223.AbstractPDF
    The impact on carbon dioxide (CO2) and nitrous oxide (N2O) emissions when applying hydrothermally carbonized (HTC) char to soil was investigated in a laboratory experiment with two HTC chars made from hemp (Cannabis sativa L.) dust and incubated for 131 d. Two fractions of hemp dust were collected during fiber processing (from fractionation and suction) and were carbonized at 230 °C for 6 h in water. Non-treated and water-washed HTC chars were used in incubation experiments, doubling the carbon concentration of the soil. As a result of adding HTC char to soil, CO2 emissions increased significantly in all cases compared to the control treatment. Washing the HTC chars easily removed dissolvable carbon (C) compounds, which significantly decreased CO2 emissions. Nitrous oxide emissions, following the incorporation of HTC char, did not differ from those of the control sample; however, washed HTC char treatments tended to emit less N2O than the corresponding unwashed samples. Hydrothermally carbonized char obtained from the suction of dust may play a greater role as a soil conditioner than HTC char from dust by fractionation because dust from suction accumulates to a larger degree during hemp fiber processing.
  • Researchpp 3224-3241Saad, A., Ratanawilai, S., and Tongurai, C. (2015). "Catalytic cracking of pyrolysis oil derived from rubberwood to produce green gasoline components," BioRes. 10(2), 3224-3241.AbstractPDF
    An attempt was made to generate gasoline-range aromatics from pyrolysis oil derived from rubberwood. Catalytic cracking of the pyrolysis oil was conducted using an HZSM-5 catalyst in a dual reactor. The effects of reaction temperature, catalyst weight, and nitrogen flow rate were investigated to determine the yield of organic liquid product (OLP) and the percentage of gasoline aromatics in the OLP. The results showed that the maximum OLP yield was about 13.6 wt%, which was achieved at 511 °C, a catalyst weight of 3.2 g, and an N2 flow rate of 3 mL/min. The maximum percentage of gasoline aromatics was about 27 wt%, which was obtained at 595 °C, a catalyst weight of 5 g, and an N2 flow rate of 3 mL/min. Although the yield of gasoline aromatics was low, the expected components were detected in the OLP, including benzene, toluene, ethyl benzene, and xylenes (BTEX). These findings demonstrated that green gasoline aromatics can be produced from rubberwood pyrolysis oil via zeolite cracking.
  • Researchpp 3242-3253Čermák, P., Rautkari, L., Horáček, P., Saake, B., Rademacher, P., and Sablík, P. (2015). "Analysis of dimensional stability of thermally modified wood affected by re-wetting cycles," BioRes. 10(2), 3242-3253.AbstractPDF
    The dimensional stability of thermally modified wood exposed to several wetting-drying cycles was analyzed. Specimens of dimensions 15×15 ×15 mm were thermally modified at 180 and 200 °C. The mass loss and chemical composition of the wood were determined in order to evaluate the effect and degree of modification. Afterwards, the radial, tangential, and volumetric swelling, anti-swelling efficiency, water absorption, water repellence efficiency, and mass loss due to wetting-drying cycles were determined and compared. The specimen’s mass tended to decrease with each additional rewetting cycle. Additional extractives that were formed via thermal decomposition leached out during wetting cycles. Thermal modification positively affected the dimensional stability of all investigated species. The wood’s swelling was reduced, a result attributed to hemicellulose degradation. Dimensional stability was improved by 24 to 30% following mild treatment and by 26 to 54% following more severe treatment. When specimens were exposed to six consecutive rewetting cycles, the swelling of the modified wood increased, whereas it slightly decreased for the control (hornification). The effective dimensional stability of thermally modified wood was reduced by 34 and 28.4% for beech, 47 and 19.6% for poplar, and 19.3 and 24.5% for spruce compared to the initial anti-swelling efficiency following the first wetting cycle.
  • Researchpp 3254-3264Chen, T., Niu, M., Wu, Z., Cai, L., and Xie, Y. (2015). "Fire performance of Si-Al ultra-low density fiberboards evaluated by cone calorimetry," BioRes. 10(2), 3254-3264.AbstractPDF
    To clarify how the fire resistance of ultra-low density fiberboards (ULDFs) was improved by the Si-Al compounds and to compare the effect of fire resistance between Si-Al compounds and fire retardant (chlorinated paraffin), the fire performance of ULDFs was evaluated by cone calorimetry. Comparing Si-Al compounds to chlorinated paraffin, the heat release rate (HRR), total heat release (THR), mass loss, total smoke release, and off-gases (CO and CO2) release of ULDFs treated with Si-Al compounds significantly decreased. However, when Si-Al compounds and chlorinated paraffins were simultaneously added, the mixed fiberboards showed the best results for peak of HRR (100.76 kW m-2), time to flameout (336s), THR (21.36 MJ m-2), and residual mass (34.26%). These results indicated that the Si-Al compounds had a significant effect on improving the fire resistance of ULDFs, and the Si-Al compounds and chlorinated paraffins have a synergistic effect in ULDFs.
  • Researchpp 3265-3276Luo, J., Zhang, J., Luo, J., Li, J., and Gao, Q. (2015). "Effect of melamine allocation proportion on chemical structures and properties of melamine-urea-formaldehyde resins," BioRes. 10(2), 3265-3276.AbstractPDF
    Melamine-urea-formaldehyde (MUF) resin was synthesized by adding melamine with a first and second portion of urea, named M1 and M2, respectively. Different allocation proportions of M1:M2 (4:0, 3:1, 2:2, 1:3, and 0:4) were used to develop five MUF (MUF-1, 2, 3, 4, and 5) resins with an F/(U+M) molar ratio of 1.05. The chemical structures, curing behaviors, and cross-section morphology of the resins were characterized. Three-ply plywood was fabricated to evaluate wet shear strength and formaldehyde emission. Results showed that when the melamine allocation proportion was increased from 0:4 to 4:0, the total methylene ether group content increased, the curing rate was elevated, and a heterogeneous cross-section of the cured resin formed, which led to a wet shear strength increase of 42.11%. When the melamine allocation proportion decreased, the free melamine content increased, the pot life was prolonged, and a highly homogeneous morphology was formed, which resulted in a decrease of 42.86% in formaldehyde emission of the resulting plywood. These results suggested that a high melamine allocation proportion, meaning that more of the MUF resin was added initially, improved the water resistance of the resulting resin, whereas a low melamine allocation proportion decreased the formaldehyde emission reduction of the resulting plywood.
  • Researchpp 3277-3292Kuusisto, J. E., and Maloney, T. C. (2015). "The effect of carbonation conditions on the properties of carbohydrate-calcium carbonate hybrid pigments," BioRes. 10(2), 3277-3292.AbstractPDF
    The influence of two polysaccharides, native corn starch and carboxymethyl cellulose (CMC), on the precipitation of calcium carbonate was examined by utilizing two different carbonation processes. In a batch process, carbon dioxide gas was fed through calcium hydroxide slurry at pH 11.5 to 12.0. The reaction was complete when the pH had been decreased to 7. In a fed-batch reaction, the carbon dioxide was dissolved in water while calcium hydroxide was pumped into the water, maintaining a constant pH of 6.0±0.5. Scanning electron microscopy, particle size analysis, and specific surface area analysis were used to characterize the structure of the precipitated calcium carbonate (PCC) pigments. In application testing, the impact of modified pigments on paper properties was examined. The results showed that carbohydrates can significantly affect the crystallization of calcium carbonate, but the influence depends on the precipitation conditions and the type and concentration of the carbohydrate added. The starch-modified PCC, produced by the fed-batch reaction, improved the mechanical properties of the paper, whereas CMC-modified PCC yielded paper with good surface and optical performance but weakened strength properties.
  • Researchpp 3293-3301Wu, F., Yang, R., and Yang, F. (2015). "Metal chlorides as effective catalysts for the one-pot conversion of lignocellulose into 5-chloromethylfurfural (5-CMF)," BioRes. 10(2), 3293-3301.AbstractPDF
    5-chloromethylfurfural (5-CMF) was produced from carbohydrates and lignocelluloses under the catalysis of Lewis acids. The millimole scale-up synthesis of 5-CMF from carbohydrates was successfully performed using metal chlorides or mixed metal chlorides as a catalyst in a heterogeneous system. The process involved the heating of the feedstock in a biphasic hydrochloric acid/organic solvent reactor over several hours. The process was later applied to raw biomass, which gave 5-CMF yields comparable to that of carbohydrates, based on the hexose content. It was found that mixed catalysts consisting of CrCl3 and ZnCl2 played an effective role in the transformation. The 5-CMF can be directly obtained in nearly 80% yield from the fructose under the mixed catalysts heterogeneous system. Bamboo pulp, eucalyptus pulp, and bagasse pulp were also directly converted into 5-CMF under this system at the yield of 32.7%, 36.2%, and 50.1%, respectively.
  • Researchpp 3302-3313Zhou, J., Fu, W., Qing, Y., Han, W., Zhao, Z., and Zhang, B. (2015). "Fabrication and performance of a glue-pressed engineered honeycomb bamboo (GPEHB) structure with finger-jointed ends as a potential substitute for wood lumber," BioRes. 10(2), 3302-3313.AbstractPDF
    With the increasing scarcity of wood as a natural resource, bamboo has become a popular substitute for wood. The present work developed a high-strength original state multi-reorganization material (GPEHB), without the use of a hot press or traditional assembly. The original bamboo units were polygonized into outer contours and milled into finger-joints on each ending. The GPEHB was organized and assembled under an external press, using industrial adhesives. The mechanical properties and thermal insulation of GPEHB were characterized. Moreover, the overall GPEHB unit bending strength was 73.15 MPa, and the parallel-to-grain compression was 55.22 MPa (higher than that of Pinus sylvestris lumber, though less than that of glued laminated bamboo). The GPEHB unit overall density was 0.24 g/cm³, 76% lower than that of glued laminated bamboo, and 50% lower than Pinus sylvestris lumber. The compressive strength of GPEHB (7 units) was 170.5 kN, while the compressive strength of GPEHB for 14 units was 493.5 kN, which meet the requirements of GB 50005 (2003). The bending strength of GPEHB 7 units was 12 kN, while that of 14 units was 37 kN. The heat conductivity coefficient for GPEHB was 0.25 W/mK, which is better than concrete and steel. The GPEHB has taken full advantage of its honeycomb-structured material, which allows it to avoid stress concentration in the regular polygonal corners.
  • Researchpp 3314-3325Yang, Z., Zhang, M., Chen, L., and Lv, B. (2015). "Non-contact detection of surface quality of knot defects on Eucalypt veneers by near infrared spectroscopy coupled with soft independent modeling of class analogy," BioRes. 10(2), 3314-3325.AbstractPDF
    A knot is a natural defect that degrades the quality of softwood and hardwood veneer. To improve efficiency, the plywood industry needs a rapid, inexpensive method of knot identification that is easy to operate and industrialize. Although a non-contact knot-detection technology based on NIR spectroscopy and soft independent modeling of class analogy (SIMCA) has been successful in detecting softwood knots, it has not yet been explored in eucalypt (hardwood) veneer. This study investigated the interaction between knot size, spectral pretreatment methods, and wavelength range selections on this model’s classification accuracy of knots and normal eucalypt wood. The study found that classification results were accurate up to 94.4% for large knot samples (10 to 15 mm in diameter) and up to 100% for knot-free samples. Spectral data for small knots (< 5 mm in diameter) impeded the model’s classification accuracy because of confusion between small knots and both large knots and normal wood. Calibration models developed with second-derivative spectra exhibited the highest accuracy, followed by models built with first-derivative spectra, models based on spectra transformed by vector normalization, and the model based on the raw spectroscopy. Wavelength ranges of 1100 to 2500 nm enabled greater classification accuracy than wavelength ranges of 780 to 1100 nm or 780 to 2500 nm.
  • Researchpp 3326-3336Tang, R., Yu, Z., Zhang, Y., and Qi, C. (2015). "Mechanisms and properties of chitosan-assisted bamboo dyeing," BioRes. 10(2), 3326-3336.AbstractPDF
    Acid dyes are often used to improve the decorative properties of bamboo products. However, the use of these dyes is problematic because they run easily. This study examined the use of chitosan as a fixing agent to address this issue. The study also investigated the interaction between dyed bamboo powder and dyed veneers pre-treated with chitosan. Powder was dyed at various pH values with acid scarlet GR and soaked in various solvents. Analyses were conducted using Fourier transform infrared spectroscopy, a zeta potential measurement analyzer, UV-visible spectroscopy, and a color measuring instrument. Pre-treated bamboo veneers were also dyed with acid scarlet GR and evaluated with the color measuring instrument, a scanning electron microscope, and an optical microscope. Chitosan functioned as a bridge and immobilized dye on the bamboo. This occurred through a chemical reaction and opposite charge attraction under acidic conditions. Pretreated dyed bamboo veneers demonstrated excellent dye uptake, color-fastness, and levelness. Therefore, chitosan shows promise for use as a fixing agent in dyed bamboo.
  • Researchpp 3337-3346Stratev, D., Hansmann, C., and Rathke, J. (2015). "Analysis of the chemical constituents of kiln-dry condensate and its technological recovery - Part 2: Semi-volatile and volatile extractives," BioRes. 10(2), 3337-3346.AbstractPDF
    The demand of the global economy for fossil resources needed for the production of fuel and basic chemicals is expected to exceed supply in the coming decades. Because of its heavy reliance on fossil fuels for increased efficiencies over the 20th century, the chemical industry has been particularly motivated to harness alternative raw materials, such as biomass, that are environmentally and economically sustainable. Biorefineries have provided stable, large-scale means of converting biomass into base chemicals, but until recently the main focus has been on the conversion of the mainly cellulosic fraction of edible plants into biofuels. Second- and third-generation biorefineries are striving to be more economically integrated and sustainable by utilizing raw material fractions to a greater extent and by not competing with the agriculture and food sector. The goal of this study was to evaluate the potential of kiln-dry condensate as a source for production of bio-based chemicals. The condensates of three typical European wood species were analyzed. Part 1 evaluated the volatile extractives; Part 2 concentrates on semi- and non-volatile extractives of kiln-dry condensates.
  • Researchpp 3347-3363Cheumani-Yona, A. M., Budija, F., Hrastnik, D., Kutnar, A., Pavlič, M., Pori, P., Tavzes, Č., and Petrič, M. (2015). "Preparation of two-component polyurethane coatings from bleached liquefied wood," BioRes. 10(2), 3347-3363.AbstractPDF
    Liquefied wood-based polyurethane wood coatings of an aesthetically acceptable light colour were prepared and characterised. Liquefied black poplar wood was obtained by solvolysis in a polyethylene glycol/glycerol mixture, and it was bleached with hydrogen peroxide. The bleaching treatment converted liquefied wood from a dark brown to a yellowish product. Polyurethane films were prepared by the curing of liquefied wood with polymeric diphenylmethane diisocyanate or trimethylolpropane toluene diisocyanate prepolymer (TMP/TDI) isocyanate-type hardeners. It was found that the selected properties of the films prepared from the bleached liquefied wood were, in general, equivalent to those prepared from unbleached liquefied wood. The mechanical properties of the films obtained with the TMP/TDI curing agent were acceptable for wood coating applications. The initial poor resistance of the films to water and ethanol was substantially improved by the addition of n-octyltriethoxysilane to the liquefied wood prior to the preparation of the polyurethane coatings; the hardness of the films also increased.
  • Researchpp 3364-3377Ching, Y. C., Rahman, A., Ching, K. Y., Sukiman, N. L., and Cheng, H. C. (2015). "Preparation and characterization of polyvinyl alcohol-based composite reinforced with nanocellulose and nanosilica," BioRes. 10(2), 3364-3377.AbstractPDF
    This work reported the thermomechanical and morphological properties of polyvinyl alcohol (PVA) nanocomposites reinforced with nanosilica and oil palm empty fruit bunches derived nanocellulose. The nanocomposites were characterized by mechanical, thermal, XRD, optical, and morphological studies. Uniformity dispersion of the nanofillers at a 3 wt% concentration has been shown by scanning electron microscopy, whereas the changes in crystallinity were demonstrated by X-ray diffraction analysis. Addition of nanosilica resulted in increased thermal stability of PVA/nanocellulose composites due to the reduction in mobility of the matrix molecules. Visible light transmission showed that the addition of 0.5 wt% nanosilica only slightly reduced the light transmission of PVA/nanocellulose composites with 3 wt% nanocellulose. The addition of a small concentration of nanosilica successfully improved the tensile and modulus properties of PVA/nanocellulose composite films. The increases in tensile strength and thermal stability were evidence of a nanosilica contribution in PVA/nanocellulose composites, inducing reinforcement, as detected by the thermomechanical properties.
  • Researchpp 3378-3392Jayamani, E., Hamdan, S., Rahman, M. R., and Bin Bakri, M. K. (2015). "Study of sound absorption coefficients and characterization of rice straw stem fibers reinforced polypropylene composites," BioRes. 10(2), 3378-3392.AbstractPDF
    In this study, both untreated rice straw stem fibers and fibers treated with sodium hydroxide were used. Maleic anhydride polypropylene (MAPP) was used to enhance adhesion of the fiber with the matrix. Composites were prepared with various combinations of fiber, ranging from 10 wt.% to 25 wt.%, and polypropylene in addition to 2 wt.% MAPP. These composites were then tested for acoustical, mechanical, thermal, infrared spectral, and morphological properties. The fibers were treated by being soaked in 5 wt.% NaOH solution at 30 °C for 30 min. The composites with treated fiber exhibited higher thermal stability, tensile strength, sound absorption, and fiber-matrix adhesion than the composites with untreated fiber. The results of sound absorption measurements showed that the composites with higher fiber content had better sound absorption than the composites with lower fiber content. The changes in the peaks in the Fourier transform infrared spectrum indicate that the alkaline treatment removed hemicellulose and lignin from the rice straw stem fibers.
  • Researchpp 3393-3408Sani, Y. M., Raji, A. O., Alaba, P. A., Aziz, A. R. A., and Wan Daud, W. M. A. (2015). "Palm frond and spikelet as environmentally benign alternative solid acid catalysts for biodiesel production," BioRes. 10(2), 3393-3408.AbstractPDF
    A carbonization-sulfonation method was utilized in synthesizing sulfonated mesoporous catalysts from palm tree biomass. Brunauer-Emmet-Teller (BET), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), and field emission scanning emission microscopy (FE-SEM) analyses were used to evaluate the structural and textural properties of the catalysts. Further, Fourier transform infrared (FT-IR) spectroscopy and titrimetric analyses measured the strong acid value and acidity distribution of the materials. These analyses indicated that the catalysts had large mesopore volume, large surface area, uniform pore size, and high acid density. The catalytic activity exhibited by esterifying used frying oil (UFO) containing high (48%) free fatty acid (FFA) content further indicated these properties. All catalysts exhibited high activity, with sPTS/400 converting more than 98% FFA into fatty acid methyl esters (FAMEs). The catalyst exhibited the highest acid density, 1.2974 mmol/g, determined by NaOH titration. This is outstanding considering the lower reaction parameters of 5 h, 5:1 methanol-to-oil ratio, and a moderate temperature range between 100 and 200 °C. The study further illustrates the prospect of converting wastes into highly efficient, benign, and recyclable solid acid catalysts.
  • Researchpp 3409-3425Lotfi, M. N. A., Husseinsyah, S., Osman, H., and Ismail, H. (2015). "Surface modification of Elateriospermum tapos seed shell recycled polypropylene composites," BioRes. 10(2), 3409-3425.AbstractPDF
    The influence of the filler content and surface modification of Elateriospermum tapos seed shell (ETSS)-filled recycled polypropylene (rPP) on the tensile, thermal, and morphological properties was investigated. Maleic acid (MA) was used for the chemical modification of ETSS. It was found that increasing the ETSS content decreased the tensile strength and elongation at break of composites. However, the modulus of elasticity increased with the addition of ETSS. The thermal properties of composites were examined using thermal analysis (TGA) and differential scanning calorimetry (DSC). The addition of ETSS indicated better thermal stability of rPP/ETSS composites. The degree of crystallinity (Xc) of the composites decreased with increasing ETSS content. The tensile strength and modulus of elasticity of modified composites was higher than unmodified composites. Surface modification with maleic acid increased the thermal stability and crystallinity of the modified rPP/ETSS composites. Scanning electron microscopy showed that the filler-matrix interaction improved with the modification of ETSS with maleic acid.
  • Researchpp 3426-3433Kaygin, B., Kaplan, D., and Aydemir, D. (2015). "Paulownia tree as an alternative raw material for pencil manufacturing," BioRes. 10(2), 3426-3433.AbstractPDF
    The Paulownia tree is one of the most important fast growing species in the World and is an ideal multipurpose tree. In this study, the potential use of Paulownia wood (Paulownia elongata) as a raw material for the pencil manufacturing industry is investigated. Currently, poplar, cedar, and juniper species are most commonly used in this industry. However, Paulownia wood is a fast growing species that can be used in the industry after 5 years on the plantation. Paulownia (Paulownia elongata), poplar (Populus tremula), and juniper (Juniperus excelsa) wood specimens were used in this study. The specimens were prepared according to related standards, and physical, mechanical, and technological properties were investigated. The data obtained from these measurements were compared statistically using ANOVA and Duncan’s Multiple Range Test. As a result, Paulownia wood exhibited favorable properties, suggesting that it would be a useful alternative raw material for the pencil manufacturing industry.
  • Researchpp 3434-3450Cui, Y., Dong, X., Tong, J., and Liu, S. (2015). "Degradation of lignocellulosic components in un-pretreated vinegar residue using an artificially constructed fungal consortium," BioRes. 10(2), 3434-3450.AbstractPDF
    The objective of this work was to degrade lignocellulosic components in un-pretreated vinegar residue (VR) using a fungal consortium. Consortium-29, consisting of P. chrysosporium, T. koningii, A. niger, and A. ficuum NTG-23, was constructed using orthogonal design combined with two-way interaction analysis. After seven days of cultivation, the reducing sugar yield reached 35.57 mg per gram of dry substrate (gds-1), which was 108.01% higher than the control (17.10 mg gds-1). Additionally, the xylanase and CMCase activity reached 439.07 U gds-1 and 8.15 U gds-1, which were 432.08% and 243.88% higher than that of pure cultures of A. niger (82.52 U gds-1) and P. chrysosporium (2.37 U gds-1), respectively. The cellulose, hemicellulose, and lignin contents decreased by 17.11%, 68.61%, and 14.44%, respectively, compared with that of the raw VR. The optimal fermentation conditions of consortium-29 were as follows: incubation temperature 25 °C, initial pH 6, initial moisture content 70%, inoculum size 1 ´ x 106 spores/mL, incubation time 5 days, urea/VR 1%, and MnSO4×H2O/VR 0.03%. This study suggests that consortium-29 is an efficient fungal consortium for un-pretreated VR degradation and has a potential application in lignocellulosic waste utilization with a low cost of operation.
  • Researchpp 3451-3461Chen, N., Rao, J., He, M., Mei, G., Huang, Q., Lin, Q., and Zeng, Q. (2015). "Preparation and properties of heat-treated Masson pine (Pinus massoniana) veneer," BioRes. 10(2), 3451-3461.AbstractPDF
    The feasibility of heat treatment of Masson pine veneers (MPVs) was evaluated based on mass loss, tensile strength, bending strength, and water absorption of the heat-treated MPVs, and its application in plywood was explored. Fourier-transform infrared and X-ray diffraction results showed that heat-treated MPVs contained a lower amount of hydrophilic groups and had an increased crystallinity. The maximum tensile strength was 59.2 MPa when MPVs were heat-treated at 210 °C for 5.0 min. The corresponding mass loss, water absorption (384 h), and bending strength values were 1.72%, 105.44%, and 83.1 MPa, respectively. Plywood produced from heat-treated MPV (210 °C, 30 min) with the best fungal durability and the lowest shear strength (1.07 MPa) still met the requirements of the Chinese National Standard (GB/T 9846.3-2004, ≥0.80 MPa) for exterior plywood. These results indicate that products based on heat-treated MPV will have increased fungal durability.
  • Researchpp 3462-3480Ofudje, E. A., Akiode, O. K., Oladipo, G. O., Adedapo, A. E., Adebayo, L. O., and Awotula, A. O. (2015). "Application of raw and alkaline-modified coconut shaft as a biosorbent for Pb2+ removal," BioRes. 10(2), 3462-3480.AbstractPDF
    The sorption capacity of untreated and alkaline-treated coconut shaft biosorbents for the removal of Pb2+ from aqueous solution was investigated in batch experiments. Effects of contact time, biosorbent dose, initial metal concentration, and pH on the sorption capacity were investigated. Optimum Pb2+ removal of 17.6 and 22.1 mg/g by untreated and alkaline-treated biomass was achieved at an initial metal concentration of 150 mg/L, a biomass dose of 0.7 g, a contact time of 80 min, and a pH of 4.0. The sorption data fitted well into the Langmuir isotherm, while kinetic modeling of the data from untreated biomass indicated conformity with the Lagergren pseudo-first-order model, whereas data from the treated biomass fit well with the Elovich model. FT-IR results gave indications of possible functional groups on the cell walls of the coconut shaft, including alcohols, amines, carboxylic acids, ester, and ethers. Thus, alkaline treatment of the coconut shafts enhanced the biosorption ability of Pb2+ onto the coconut shaft biomass.
  • Researchpp 3481-3491Ruponen, J., Čermák, P., Rhême, M., Miettinen, A., Rohumaa, A., and Rautkari, L. (2015). "Influence of welding time on tensile-shear strength of linear friction welded birch (Betula pendula L.) wood," BioRes. 10(2), 3481-3491.AbstractPDF
    The purpose of this work was to determine the optimal welding time for linear friction welding of birch (Betula pendula L.) wood while keeping the other parameters constant and at similar levels compared to other species in a similar density range. Specimens with dimensions of 20 × 5 × 150 mm3 were welded together, and the influence of welding time (2.5, 3.0, 3.5, and 4.0 s) on the mechanical properties of the specimens was determined. The studies included a tensile-shear strength test as well as visual estimation of wood failure percentage (WFP). Additionally, X-ray microtomographic imaging was used to investigate and characterise the bond line properties as a non-destructive testing method. The highest mean tensile-shear strength, 7.9 MPa, was reached with a welding time of 3.5 s. Generally, all four result groups showed high, yet decreasing proportional standard deviations as the welding time increased. X-ray microtomographic images and analysis express the heterogeneity of the weld line clearly as well. According to the averaged group-wise results, WFP and tensile-shear strength correlated positively with an R2 of 0.93. An extrapolation of WFP to 65% totals a tensile-shear strength of 10.6 MPa, corresponding to four common adhesive bonds determined for beech.
  • Researchpp 3492-3506Rantanen, J., Dimic-Misic, K., Pirttiniemi, J., Kuosmanen, P., and Maloney, T. C. (2015). "Forming and dewatering of a microfibrillated cellulose composite paper," BioRes. 10(2), 3492-3506.AbstractPDF
    An approach is demonstrated for the manufacturing of a microfibrillated cellulose (MFC) composite paper. A key element in the manufacturing paradigm is the use of high consistency suspensions to improve retention and minimize the need for water removal after forming. The rheological characterization of the composite furnish, which contained 70% structured pigment, 20% MFC, and 10% pulp fibers, revealed a gel-like shear thinning behavior of the suspension, which differs greatly from traditional fiber-based papermaking furnishes. The results from laboratory and pilot scale studies show that the headbox consistency range from 5 to 10% offers the best combination of processing, forming characteristics, retention, and dewatering. While the furnish dewatering in laboratory scale was very problematic, under suitable dynamic conditions the wire section dewatering was excellent. The results of this study suggest that the MFC composite can be manufactured on a modified paper machine and that the final product will have an attractive cost structure.
  • Researchpp 3507-3519Luo, H., Ren, S., Ma, Y., Fang, G., and Jiang, G. (2015). "Preparation and properties of kraft lignin-N-isopropyl acrylamide hydrogel," BioRes. 10(2), 3507-3519.AbstractPDF
    Kraft lignin was used to prepare kraft lignin-N-isopropyl acrylamide hydrogel (KNIAH). The results indicated that using a 1:2 mass ratio of KL-to-N-isopropyl acrylamide (NIPAM), 48 h reaction time, and 1.5 mL of crosslinking agent yielded KNIAH with the maximum swelling degree (209.3%). The crosslinking reaction was verified by C-N shifting at 1272 cm-1 and increased C=O bonding at 1720 cm-1. KNIAH with a smooth and uniform surface was created. DSC demonstrated that free water combined with KNIAH at 200 °C, after which KNIAH began exothermic decomposition. TGA shows that KNIAH with good performance of heat resistance and degradation. Absorption was maximized at 20 °C; low temperature and neutral solution was conducive to water absorption. Decolorization increased with decreasing concentration and pH value.
  • Researchpp 3520-3530Yu, H., Cao, Y., Fang, Q., and Liu, Z. (2015). "Effects of treatment temperature on properties of starch-based adhesives," BioRes. 10(2), 3520-3530.AbstractPDF
    Starch-based adhesives were developed by hydrolyzing starch with polyvinyl alcohol under alkaline and acidic conditions at various treatment temperatures. The chemical and physical structures of the corn starch and hydrolyzed starch were characterized with Fourier Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and scanning electronic microscopy (SEM). Thermal degradation and bond strength were also evaluated. The results indicated that the bond strength of starch adhesives reached a maximum value at 40 °C. The FI-IR results showed that the amount of hydroxyl groups first increased and then decreased with increasing treatment temperature. When the treatment temperature was 55 °C the crystallinity of treated starch was the lowest and the thermal resistance also the weakest; it decreased by 10.1% and 13.6% respectively compared to untreated starch. Obvious erosion could be observed from the SEM images of treated starch. In addition, the interaction of polyvinyl alcohol (PVA) and starch also could be observed, and the results indicated that the compatibility between starch and PVA became better and better as the treated temperature was increased.
  • Researchpp 3531-3540Zhang, T., Tu, D., Peng, C., and Zhang, X. (2015). "Effects of heat treatment on physical-mechanical properties of Eucalyptus regnans," BioRes. 10(2), 3531-3540.AbstractPDF
    Eucalyptus regnans was subjected to thermal treatment. The samples were placed in superheated vapors at 120, 130, 140, 150, 160, 170, 180, 190, and 200 °C at ambient pressure to determine the effect of heat treatment on the physical-mechanical properties of Eucalyptus regnans. The results showed that heat treatment played an important role in the impact toughness, nail-holding ability, surface hardness, bending strength, and bending modulus of elasticity of E. regnans. The nail-holding ability, surface hardness, bending strength, and bending modulus of elasticity of E. regnanstreated at 120 and 130 °C increased related to untreated wood, but decreased at 140 to 200 °C. The impact toughness decreased after heat treatment from 120 to 200 °C, while the bending modulus of elasticity increased. Consequently, heating at 120 and 130 °C was found to be more suitable to ensure sufficient strength.
  • Researchpp 3541-3552Euring, M., Kirsch, A., and Kharazipour, A. (2015). "Hot-air/hot-steam process for the production of laccase-mediator-system bound wood fiber insulation boards," BioRes. 10(2), 3541-3552.AbstractPDF
    In this study, a new technical process for hardening wood fiber insulation boards is introduced. During the dry-process, the fibers are usually glued with polymeric-diphenylmethane-diisocyanate (pMDI) and hardened to wood fiber insulation boards using a steam-air mixture. However, the maximum temperature reached in the steam-air process was 100 °C, and it was impossible to use an alternative binding agent for the gluing of the wood fiber insulation boards other than pMDI. When incubated with laccase-mediator-system (LMS) as a naturally based bonding system, temperatures of over 120 °C are required because of the chemical wood composition, especially the lignin. In this case, the hot-air/hot-steam process offers new technical opportunities for realizing temperatures above 100 °C. In this study, wood fiber insulation boards were glued with LMS, vs. reference boards with inactivated LMS, laccase alone, and 4% pMDI. Then, the boards were hardened using one of three processes: with steam-air mixture, with hot-air, and with hot-air/hot-steam. Through the hot-air/hot-steam process, temperatures of well over 120 °C were attainable. All the insulation boards hardened using the hot-air/hot-steam process showed better physical and technical properties than those hardened with steam-air mixture or hot-air alone. The reason for this is a sudden increase of temperature after the adding of steam because high temperatures insure that the LMS activated wood fiber surface lignins are completely plasticized. As a result the physical-technological properties such as internal bond strength, compression strength, and short term water absorption of insulation boards treated with LMS were comparable to those boards treated with 4% pMDI.
  • Researchpp 3553-3563Ruan, P., Raghavan, V., Gariepy, Y., and Du, J. (2015). "Characterization of flax water retting of different durations in laboratory condition and evaluation of its fiber properties," BioRes. 10(2), 3553-3563.AbstractPDF
    Water retting is a traditional retting method that enables the low-cost production of bast fibers. This study investigated the retting of flax straws by distilled water for three different durations at room temperature in laboratory condition. The retting quality was evaluated in terms of the weight loss and degumming rate together with the fiber properties, which included color, linear density, and tensile properties. The degumming rate was defined as the percentage change in pectin content of phloem regions from the raw flax to water-retted flax. It was found that the dissolution of pectin and other contaminating materials during the beginning retting stage must have played an important role in pectin (content) and weight loss besides pectin degradation, and water retting gradually improved both the apparel properties, such as whiteness and fineness, and the mechanical properties of the fibers. Given the results, a water retting duration of six days should be sufficient to provide sound retting efficiency and reasonable fiber properties.
  • Researchpp 3564-3576Gutiérrez-Soto, G., Medina-González, G. E., García-Zambrano , E. A., Treviño-Ramírez, J. E., and Hernández-Luna, C. E. (2015). "Selection and characterization of a native Pycnoporus sanguineus strain as a lignocellulolytic extract producer from submerged cultures of various agroindustrial wastes," BioRes. 10(2), 3564-3576.AbstractPDF
    A native strain of Pycnoporus sanguineus (CS2) was selected because of its lignocellulolytic potential on a color-based agar plate screening system; pectinolytic and amylolytic capabilities were also assessed. The effects of different lignocellulosic substrates under submerged cultures of selected fungi on the enzymatic production of cellulases, xylanases, amylases, and laccases were evaluated. Seven different treatments, in which different combinations of wheat straw (WS), wheat bran (WB), orange peels (OP), grapefruit peels (GP), and apple peels (AP) were used, were established. Controls of 2% (w/v) carboxymethyl-cellulose (CMC) and xylan were used in a rich medium for basidiomycetes (RMB). The highest titers were achieved using OP-based cultures, with large titers of CMCases (33.5 U), avicelases (15.7 U), ß-D-glucosidase (72.9U), and xylanases (18.3 U). The best levels of amylase and laccase activity were obtained in the RMB plus CMC (RMB-CMC) (7.2 U) and in the medium OF/AP/GP (6.4 U), respectively. The relative molecular sizes of cellulase, xylanase, and amylase were 66.2, 56.5, and 90.8 kDa, respectively. Laccase and amylase had maximum activities at 60 °C whereas cellulase and hemicellulase had maximum activities at 70 °C. The optimal pH for cellulases, xylanases, and amylases was 5.0 in every case, and more than 95% activity was observed at pH 6. These results reveal some efficient operating parameters for the application of these enzymatic extracts as adjuvants to improve animal nutrition.
  • Researchpp 3577-3601Then, Y. Y., Ibrahim, N. A., Zainuddin, N., Chieng, B. W., Ariffin, H., and Wan Yunus, W. M. Z. (2015). "Effect of 3-aminopropyltrimethoxysilane on chemically modified oil palm mesocarp fiber/poly(butylene succinate) biocomposite," BioRes. 10(2), 3577-3601.AbstractPDF
    Consecutive superheated steam-alkali treatment was introduced to modify oil palm mesocarp fiber (OPMF) prior to biocomposite fabrication. The biocomposite made up of 70 wt.% modified OPMF (SNOPMF) and 30 wt.% poly(butylene succinate) (PBS) was prepared by melt blending followed by compression molding. A silane coupling agent of 3-aminopropyltrimethoxysilane (APTMS) was also incorporated into the SNOPMF/PBS biocomposite during the compounding process to impart better adhesion at the SNOPMF-PBS interface. The experimental results revealed that the tensile, flexural, and impact strengths were enhanced by 16, 30, and 15%, respectively, after the introduction of 2 wt.% APTMS to the SNOPMF/PBS biocomposite. Similarly, the resistance to water uptake and thickness swelling of this biocomposite was improved by 34 and 49%, respectively, relative to SNOPMF/PBS biocomposite. The SEM observation of the tensile fracture surface showed that APTMS improved the interfacial adhesion between SNOPMF and PBS. Based on the results, it can be deduced that APTMS could be a good coupling agent for improving the SNOPMF-PBS adhesion and, thereby, lead to a water resistant biocomposite of enhanced mechanical properties.
  • Researchpp 3602-3614Carrasco, E. V. M., and Mantilla, J. N. R. (2015). "Failure criteria for shear strength evaluation of bonded joints according to grain slope under tension load," BioRes. 10(2), 3602-3614.AbstractPDF
    Failure criteria from six theories were applied to estimate the shear strength of the adhesive line in terms of grain slope when under loaded tension stress. The shear stresses of the adhesive line as a function of the angle of the wood grain were determined by experimental tests. Specimens were obtained from 12 Eucalyptus saligna wood beams. They were prepared with varying angles of the grain (0°, 15°, 30°, 45°, 60°, 75°, and 90°) in relation to load application, following the requirements of the Brazilian standard. From the results of the six failure criteria and experimental results, robust statistical analysis was carried out; it was thus possible to adapt the models to determine the shear strength of the adhesive line as a function of the angle of the wood grain. The six mathematical models evaluated do not show statistical significance (p < 0.05) in their original format. With modifications, the models showed statistical significance only with the formulations of DIN 1052 and Karlsen.
  • Researchpp 3615-3624James, A. M., Yuan, W., Boyette, M. D., and Wang, D. (2015). "The effect of air flow rate and biomass type on the performance of an updraft biomass gasifier," BioRes. 10(2), 3615-3624.AbstractPDF
    Airflow and the type of biomass are the two most important factors influencing the performance of a biomass gasifier. In this research, the effects of air flow rate (air-fuel equivalence ratios of 0.21, 0.25, and 0.29) and biomass type (woody biomass, agricultural residue, and perennial grass) on the performance of an updraft biomass gasifier were evaluated based on its tar and producer gas generation. It was found that increasing airflow increased the formation of tar species for all biomass types studied, but no significant differences in producer gas composition were found when the air-fuel equivalence ratio was changed. Thus, air-fuel equivalence ratios ranging from 0.21 to 0.25 were deemed appropriate for minimal tar generation. The results also showed that different biomass types generated producer gas with significantly different tar contents: woodchips yielded the most tar, followed by sorghum stover and prairie hay. The higher heating value of producer gas from various biomass types was also significantly different. Wood chip-derived producer gas had the greatest higher heating value, followed by prairie hay and sorghum stover. The carbon monoxide content in the produce gas of the three biomass types also exhibited significant differences with varying biomass type, similar to the higher heating value, but there were no significant differences in the H2 content with varying biomass type or airflow.
  • Researchpp 3625-3637Lin, L. D., Chang, F. C., Ko, C. H., Wang, C. Y., and Wang, Y. N. (2015). "Properties of enzyme pretreated Wikstroemia sikokiana and Broussonetia papyrifera bast fiber pulps," BioRes. 10(2), 3625-3637.AbstractPDF
    Xylanase, pectinase complex, and BL11 pectinase were employed for the pretreatment of gampi and paper mulberry bast fiber pulps prior to chlorine dioxide bleaching. The bleaching efficiencies of the pulps with different enzymatic pretreatments were investigated. Accelerated aging by heat-humidity treatment was also conducted to evaluate yellowing phenomena and to estimate the prevention of brightness reversion (brightness retention) by enzymatic pretreatment. The order of active chlorine required with respect to pretreatment was pectinase complex > xylanase > BL11 pectinase for soda and soda/oxalate gampi pulps and pectinase complex > BL11 pectinase > xylanase for soda and soda/oxalate paper mulberry pulps. Higher brightness retention values were observed for soda/oxalate pulps compared to soda pulps. The brightness retention levels for gampi pulps and mulberry pulps after ClO2 bleaching with enzymatic pretreatment were higher than the levels of ClO2 and NaClO bleaching pulps. Enzymatic treatments were thus able to reduce the usage of ClO2 and to assist in producing photo-stable paper materials for art and artifact-repairing applications. Thus, enzymatic pretreatment of the pulp has the potential to meet world trends and environmental sustainability for pulp and paper industries.
  • Researchpp 3638-3656Ponomarev, D. A., Mettee, H. D., and Miller, J. (2015). "Empirically estimated heats of combustion of oxygenated hydrocarbon bio-type oils," BioRes. 10(2), 3638-3656.AbstractPDF
    An empirical method is proposed by which the heats of combustion of oxygenated hydrocarbon oils, typically found from wood pyrolysis, may be calculated additively from empirically predicted heats of combustion of individual compounds. The predicted values are in turn based on four types of energetically inequivalent carbon and four types of energetically inequivalent hydrogen atomic energy values. A method is also given to estimate the condensation heats of oil mixtures based on the presence of four types of intermolecular forces. Agreement between predicted and experimental values of combustion heats for a typical mixture of known compounds was ± 2% and < 1% for a freshly prepared mixture of known compounds.
  • Researchpp 3657-3665Rogoziński, T., Wilkowski, J., Górski, J., Czarniak, P., Podziewski, P., and Szymanowski, K. (2015). "Dust creation in CNC drilling of wood composites," BioRes. 10(2), 3657-3665.AbstractPDF
    This paper presents the particle-size distribution of dust created by the drilling of selected wood composites, which was carried out using a CNC machine. The particle-size distribution was studied through two methods. Two analyses were performed: the sieve analysis of samples from the whole mass of collected dust and the laser diffraction analysis of the finest fraction isolated by sieving. The results presented general information about the particle-size distribution of the dust, as well as detailed information on the content of the finest particles. This information revealed that the particles might pose a potential risk to the health of workers employed in the woodworking industry. This potential risk is due to the possibility of their dispersion in the atmosphere surrounding the workplace and their size, which allows them to be respirable. The relationship between the fineness of the dust and the type of wood composite was also tested. Most ultrafine particles are formed during the drilling of fibreboards and are especially produced in traditional wet technology.
  • Researchpp 3666-3681Dai. Q., Ren, J., Kong, W., Peng, F., and Meng, L. (2015). "Adsorption kinetics and thermodynamics of cellulose dinitrobenzoate prepared in ionic liquid for the removal of creatinine," BioRes. 10(2), 3666-3681.AbstractPDF
    Creatinine is one of the major toxins in patients suffering from chronic renal failure. In this paper, cellulose dinitrobenzoate, with a degree of substitution (DS) of 0.15, was used as an oral adsorbent for creatinine adsorption. Cellulose dinitrobenzoate was prepared by modification of cellulose with 3,5-dinitrobenzoyl chloride in 1-butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid as a homogenous medium. The effects of contact time, pH, adsorption temperature, and initial concentration of creatinine on the adsorption per unit mass of cellulose dinitrobenzoate were studied, comparatively. Results showed that the maximum adsorption per unit mass for creatinine was 3.88 mg/g. Furthermore, the adsorption process was spontaneous and exothermic. It was determined that the experimental results were well fitted to the pseudo-second-order rate equation and the Freundlich adsorption isotherm. Compared with traditional oral adsorbents, this cellulose-based adsorbent was biocompatible and could remove creatinine from dialysate effectively.
  • Researchpp 3682-3693Vargas, F., González, Z., Rojas, O., Garrote, G., and Rodríguez, A. (2015). "Barley straw (Hordeum vulgare) as a supplementary raw material for Eucalyptus camaldulensis and Pinus sylvestris kraft pulp in the paper industry," BioRes. 10(2), 3682-3693.AbstractPDF
    The present study shows that barley straw (Hordeum vulgare) can be a supplementary raw material of softwoods and hardwoods such as Pinus sylvestris and Eucalyptus camaldulensis, respectively,for the production of cellulose and paper, reducing an agricultural residue that has no added value. Barley straw has a lower content of cellulose at 36.4% than P. sylvestris and E. camaldulensis, but it contains a lower quantity of lignin, 15.9%. After pulping with soda anthraquinone (AQ), high contents of cellulose (56.5 to 67.5%) and holocellulose (>80%) were attained. Paper sheet properties were able to reach, and even improve upon, those of wood species (Pinus and Eucalyptus) pulped with kraft. Better values of total yield (56.5%), Kappa number (8.9), and ISO brightness (36.4%), were attained for paper sheets from barley straw pulp versus E. camaldulensis and P. sylvestris, respectively, and comparable values for viscosity, tensile, and burst index were obtained.
  • Researchpp 3694-3701Xia, X., Wang, X., Tong, S., and He, Z. (2015). "Impact of causticizing calcium carbonate from soda pulping of wheat straw on AKD sizing," BioRes. 10(2), 3694-3701.AbstractPDF
    The causticizing calcium carbonate (CCC) produced in the causticizing stage of the chemical recovery process in alkaline pulping of wheat straw has a high silicate content and is difficult to convert to calcium oxide in the lime kiln. The CCC can be utilized as a paper filler to avoid costly lime re-burning, but the silicate content of the CCC can have a negative impact on the wet-end chemistry of the papermaking process. In this paper, the effect of the silicate content of the CCC filler on AKD sizing was investigated. CCC fillers of various silicate contents were prepared in the lab by causticizing green liquor from the soda pulping of wheat straw and were added to fiber suspensions at the wet end of the papermaking process. The results show that the impact of the CCC filler on AKD sizing was associated with its silicate content. As the silicate content increased, the specific surface area and negative charge density of the CCC particles markedly increased, resulting in more AKD adsorption onto the CCC particles instead of fibers.
  • Researchpp 3702-3712Li, J., Zhang, H., Li, J., Hu, H., and Cao, Z. (2015). "Fiber characteristics and bonding strength of poplar refiner-chemical preconditioned alkaline peroxide mechanical pulp fractions," BioRes. 10(2), 3702-3712.AbstractPDF
    In China, alkaline peroxide mechanical pulping performed with refiner-chemical preconditioning (P-RC APMP) is well known to produce fiber with high bulk, opacity, and light scattering coefficient but weak bonding and strength properties. In this study, the characteristics of different P-RC APMP fiber fractions were investigated, and their effects on bonding strength properties were determined. The results showed that there was only 5.8% R30 fiber fraction and 14.1% P100/R200 fiber fraction, and the specific surface area increased from R30 to P100/R200. The tensile index increased by 51.85% and the bonding index increased by 15.35%, when the fibers were changed from the R30 fraction to the P100/R200 fraction. The short fiber fraction (P100/R200 fraction) had smaller fiber length and coarseness but larger specific surface area and greater surface charge density than the long fiber fraction (R30 fraction). The fiber specific surface area and surface charge density made significant contributions to the bonding capacity, whereas fiber coarseness and length were negatively correlated with the tensile index.
  • Researchpp 3713-3723Zemnukhova, L. A., Panasenko, A. E., Artem'yanov, A. P., and Tsoy, E. A. (2015). "Dependence of porosity of amorphous silicon dioxide prepared from rice straw on plant variety," BioRes. 10(2), 3713-3723.AbstractPDF
    Contents of silica and extractive substances in rice straw depending on rice varieties were investigated. The samples of amorphous silica were prepared, their microelement composition and morphology were investigated, and the values of true and bulk density were estimated. The porous structure of the samples was studied by the Brunauer-Emmett-Teller (BET) method and by water vapour sorption; the specific surface values, as well as the pore diameter and volume, were also determined. Sorption properties of the SiO2 surface were analyzed on a sample of Mn2+-ions and the organic dyes brilliant green and methylene blue.
  • Researchpp 3724-3735Xu, S., Xiong, C., Tan, W., and Zhang, Y. (2015). "Microstructural, thermal, and tensile characterization of banana pseudo-stem fibers obtained with mechanical, chemical, and enzyme extraction," BioRes. 10(2), 3724-3735.AbstractPDF
    Banana pseudo-stem fibers (BPSFs) have desirable tensile properties. In this study, BPSFs were extracted using mechanical, chemical, and enzymatic methods. The aim was to evaluate the effect of these three extraction methods on the tensile, thermal, and morphological properties of BPSFs. Microstructural analysis showed the presence of structural and arch fibers in banana pseudo-stem (BPS). The average tensile strength and elongation for mechanically, chemically, and enzyme-extracted BPSFs were 210, 333, and 235 MPa, and 0.8%, 1.6%, and 1.4%, respectively. Young’s modulus was enhanced by 19.1% in the mechanically extracted BPSFs compared with that of chemically extracted BPSFs. The morphology of BPSFs was correlated with their tensile properties via scanning electron microscopy (SEM) image analysis. Fourier transform infra-red (FTIR) and X-ray diffraction (XRD) analyses of fibers showed that chemically extracted BPSFs contained less hemicellulose and lignin with a crystallinity index of 61.2%. Chemically extracted BPSFs exhibited enhanced thermal properties over mechanically extracted BPSFs. Mechanically extracted BPSFs demonstrated similar thermal and tensile properties to chemically and enzyme-extracted BPSFs. Thus, mechanically extracted BPSFs could act as highly suitable reinforcing agents in bio-based composite material preparation. Given that mechanical methods need no chemicals and they are environmentally friendly, such techniques have potential applications.
  • Researchpp 3736-3748Chen, X., Liu, H., Xia, N., Shang, J., Tran, V., and Guo, K. (2015). "Preparation and properties of oriented cotton stalk board with konjac glucomannan-chitosan-polyvinyl alcohol blend adhesive," BioRes. 10(2), 3736-3748.AbstractPDF
    The use of formaldehyde-free, biomass-based composites has gained increasing attention in recent years because of their environmental benefits and superior strength properties. In this study, oriented cotton stalk board (OCB) was fabricated with an environmentally friendly, water-based konjac glucomannan-chitosan-polyvinyl alcohol (KCP) blend adhesive using hot pressing technology. The effects of pressing parameters on the physical and mechanical properties of oriented cotton stalk board were examined in order to obtain optimal pressing parameters. Interfacial bonding surface was also examined with a scanning electron microscope and a fluorescence microscope. The optimal physical and mechanical properties were obtained at a pressing temperature of 150 °C for 15 min with a target density of 0.8 g/cm3 during hot pressing. Adhesive content and hot pressing pressure had significant influences on adhesion. Mechanical interlocking was also observed between cotton stalks and the adhesive. OCB with KCP blend adhesive has comparable mechanical properties to that with urea formaldehyde resin or phenolic formaldehyde resin. OCB resinated with KCP blend adhesive is environmental friendly and has potential applications in furniture and interior decoration with less stringent requirements for water resistance.
  • Researchpp 3749-3756Kanthavel, K., Palanisamy, R., and Vivek, S. (2015). "Investigation of the mechanical properties of bagasse fiber-reinforced epoxy composite using Taguchi and response surface methodology," BioRes. 10(2), 3749-3756.AbstractPDF
    Fiber-reinforced polymer composites are widely used in various applications because of their mechanical properties and ease of manufacture. Fiber-reinforced plastics are being developed using synthetic fiber and natural fibers of bagasse, palm biomass, etc. In this study, the mechanical strength of bagasse fiber-reinforced epoxy composite was investigated using a Design of Experiment technique. The parameters of fiber volume percentage, alkali concentration, and treatment time with three levels were considered, and an L27 design matrix was developed using the Taguchi orthogonal array. The bagasse was first treated with sodium hydroxide solution (NaOH); subsequently, 27 specimens were developed for experimental investigation. The mechanical strength of newly developed bagasse fiber-reinforced epoxy composite was investigated using a three-point bending testing machine. The flexural strength was calculated using three-point bending strength for length versus load combination. The analysis and optimization was done using the Taguchi method, and a second-order mathematical model was developed using response surface methodology (RSM). A significant performance improvement in the flexural strength of the newly developed composite was found.
  • Researchpp 3757-3774Cobreros, C., Reyes-Araiza, J. L., Manzano-Ramírez, A., Nava, R., Rodríguez, M., Mondragón-Figueroa, M., Miguel Apátiga, L., and Rivera-Muñoz , E. M. (2015). "Barley straw ash: Pozzolanic activity and comparison with other natural and artificial pozzolans from Mexico," BioRes. 10(2), 3757-3774.AbstractPDF
    The construction industry is one of the largest and most active growth sectors worldwide. It presents an important environmental impact, and one way to reduce the impact of the construction activity is to substitute pozzolanic materials for ordinary Portland cement. In this work, barley straw, barley straw ash, and other natural and artificial pozzolans from Mexico were characterized and compared. Also, the pozzolanic activity of barley straw ash was compared with the pozzolanic properties of some natural and artificial pozzolans from Mexico. Materials considered included recycled dust of fired clay brick, fly ash, volcanic ash, and wheat straw ash.
  • Researchpp 3775-3789Ülker, O., and Burdurlu, E. (2015). "Effects of some mineral wools and adhesives on burning characteristics of particleboard," BioRes. 10(2), 3775-3789.AbstractPDF
    In this study, effects of adhesive and additive's type and ratio on burning characteristics of particleboard (PB) added glass wool (GW) and rock wool (RW) were researched. PB's furnish was derived from 50% Crimean pine, 30% Eastern Black Sea oak, 15% quaking aspen, and 5% residues of wood machining, and moisture content of furnish was 1.5 to 3%. Seventy PBs with 0.64 g/cm3 density, urea formaldehyde (UF)/melamine formaldehyde (MF) fixed amount, 14 mm thickness, 45x45 cm2 dimensions and 10%, 15%, 20% SW/GW additives were produced. The 150 ºC pressing temperature with 25 kg/cm2 compression pressure was constant. Burning tests for determination of ignition time, flaming combustion temperature, flaming combustion duration, smoldering combustion duration, and mass loss during burning were made according to DIN4102 standards. According to the results of the tests, adhesive type did not affect ignition time and mass loss. While flaming combustion temperature of PB with UF was 19% higher, flaming combustion duration and smoldering combustion duration was 32% and 29% lower than those of PB with MF, respectively. While ignition time of PB with GW was 50% higher than that of PB with RW, changes in burning properties were similar for both PBs. An increase in the content of GW and RW affected burning properties of PB positively and an increase of ignition time up to 196% were obtained.
  • Researchpp 3790-3797Zhou, H., Han, L., Ren, H., and Lu, J. (2015). "Size effect on strength properties of Chinese larch dimension lumber," BioRes. 10(2), 3790-3797.AbstractPDF
    An experimental study was conducted to investigate the effect of size on the strength properties of Chinese larch (Larix gmelinii) dimension lumber. 7546 pieces of dimension lumber were sampled in three sizes, 40 by 65 mm, 40 by 90 mm, and 40 by 140 mm. After visually-grading and grouping, mechanical properties of bending strength, tensile strength, and compression strength parallel to grain were measured in a full-size test. Using nonparametric estimates, the combined length and width size effect parameters of H and L were 0.21 and 0.23 for the bending strength. The width effect parameters were 0.29 in H and 0.33 in L for the ultimate tensile strength parallel to grain. The width effect parameters of H and L were 0.12 and 0.20 for the ultimate compression strength parallel to grain. These size effect factors between H and L could be used when using the lumber for practical purposes.
  • Researchpp 3798-3810Li, B., Zhang, Z., Li, W., and Peng, X. (2015). "Model for tangential tensioning stress in the edge of circular saw blades tensioned by multi-spot pressure," BioRes. 10(2), 3798-3810.AbstractPDF
    In this study, a mathematical model of tangential tensioning stress in the edge of a circular saw blade tensioned by multi-spot pressure was established by theoretical analysis for the quality control of circular saw blades. The multi-spot pressure tensioning process was assumed to include three mechanical processes: the one-spot pressure process; the process of elastic deformation of a disk with a through-hole subjected to uniform, radial compressive stress; and the stress superposition process. The tangential tensioning stress on the edge of the circular saw blade could be accurately predicted by the established mathematical model. The model for the tangential tensioning stress on the edge of the circular saw blade tensioned by multi-spot pressure was shown to be correct by measured values.