NC State
  • Researchpp 259-267Chalamcherla, V. L., Singaracharya, M. A., and Lakshmi M., V. (2010). "Amino acids profile of the lignocellulosic feed treated with cellulase-free lignolytic mutants of Pleurotus ostreatus," BioRes. 5(1), 259-267.AbstractPDF
    Defining and quantifying amino acid requirements will become an important consideration in the next generation of feeding schemes for dairy cattle beyond the current emphasis on identification of limiting amino acids. In this context different amino acid profiles of untreated, urea treated, fungal treated, and urea plus fungal treated lignocellulosic feed by both P. ostreatus wild and its two cellulase-minus/ less lignolytic mutants were analyzed. Cellulase-free mutant strains were obtained after 20 minutes of exposure to UV light and 0.4 seconds to X-rays. A UV mutant of P. ostreatus (POM1) exhibited better performance than the X-ray mutant (POM2) in terms of production of less cellulolytic and more lignolytic enzymes. Urea treatment of straw enhanced the total amino acid content by less than a factor of two, while the fungal treatment improved it by 13-14 times. Fungal treatment of urea-treated straw improved the total amino acid content by a factor of 15, indicating the importance of urea in the straw. Further, the fungal treatment of urea-treated straw enhanced the quantity of amino acids such as glutamine, glycine, aspergine, etc. by 15-20 times. The quantity of limiting amino acids such as methionine, lysine, and histidine was also enhanced by 8 to 10 times through the fungal treatment. Maximum amounts of all the amino acids were found in urea plus fungal (POM1) treated paddy straw than in only fungal treated and only urea treated paddy straws.
  • Researchpp 268-275Taşkın, E., Eltem, R., and Soyak, E. (2010). "Enhancement of solid state fermentation for production of penicillin G on sugar beet pulp," BioRes. 5(1), 268-275.AbstractPDF
    In this study, two local strains of Penicillium chrysogenum named EGEK458 and EGEK469 were selected for enhancement of Penicillin G (PenG) production under solid state fermentation (SSF) conditions. These two strains were selected among seven strains according to their fermentation yields for PenG production during previous tests under submerged fermentation conditions. Sugar beet pulp, an agro-industrial residue of the sugar industry, was used as an inert support for the first time in PenG production under SSF. In order to enhance the production of PenG, two points of moisture level and three concentration values of nutrients (impregnated in solid support), which are the key parameters in production of PenG, were compared. As the yields from solid and submerged fermentation were compared, 570U/g of PenG – almost 15 times higher quantities of its production vs. submerged conditions – were obtained under SSF conditions in 50 hours by the strain EGEK458. The conditions for the enhanced production of PenG were 65% moisture content with a four-fold concentrated nutrients impregnated solid support.
  • Researchpp 276-290Zhao, Q., Pu, J., Mao, S., and Qi, G. (2010). "Process optimization of tetra acetyl ethylene diamine activated hydrogen peroxide bleaching of populus nigra CTMP," BioRes. 5(1), 276-290.AbstractPDF
    To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED) was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp consistency 10%, bleaching temperature 70oC, bleaching time 60 min when the charge of H2O2 was 4%, NaOH charge 2%, and molar ratio of TAED to H2O2 0.3. The pulp brightness gain reached 23.6% ISO with the optimized bleaching conditions. FTIR analysis indicated that the H2O2/TAED bleaching system can decrease carbonyl group further than that of conventional H2O2 bleaching, which contributed to the higher bleaching efficiency and final brightness. The H2O2/TAED bleaching had stronger oxidation ability on lignin than that of H2O2 bleaching.
  • Researchpp 291-302Bouiri, B., and Amrani, M. (2010). "Production of dissolving grade pulp from alfa," BioRes. 5(1), 291-302.AbstractPDF
    Alfa, also knows as Stipa tenacissimaI or “halfa”, is grown in North Africa and south Spain. Due to its short fiber length, paper made from alfa pulp retains bulk and takes block letters well. In this study alfa was evaluated for bleached pulp production. Two cellulose pulps with different chemical compositions were pulped by a conventional kraft process. One sample was taken from the original alfa material and another from alfa that had been pretreated by diluted acid. The pulp produced from the pretreated alfa was bleached by the elemental-chlorine-free sequences DEPD and DEDP. The yield, Kappa number, brightness, and α- cellulose content of bleached and unbleached pulps were evaluated. The results showed that during the chemical pulping process, treated alfa cooked more easily than the original alfa. The treated alfa pulp also showed very good bleaching, reaching a brightness level of 94.8% ISO with a yield of 93.6% at an α-cellulose content 96.8(%) with a DEDP bleaching sequence, compared to 83.2% ISO brightness level, 92.8% yield, and 95.1% α-cellulose content for bleached pulp with a DEPD bleaching sequence. Therefore, this alfa material could be considered as a worthwhile choice for cellulosic fiber supply.
  • Researchpp 303-315Ding, C., Qian, X., Shen, J., and An, X. (2010). "Preparation and characterization of conductive paper via in-situ polymerization of pyrrole," BioRes. 5(1), 303-315.AbstractPDF
    Electrically conductive paper was prepared via in-situ chemical oxidative polymerization of pyrrole by using ferric chloride as an oxidant and p-toluenesulfonic acid (PTSA) as a dopant. The deposition of polypyrrole (PPy) on the fiber surface was verified by ATR-FTIR and SEM analyses. Pyrrole concentration had a significant effect on the surface resistivity of conductive paper, especially when the pyrrole concentration was less than 1.8 g·L-1. The conductivity of the PPy-coated paper could be controlled by adjusting pyrrole concentration. The threshold concen-tration of pyrrole was 1.2 g·L-1 when the molar ratio of dopant to pyrrole was 2:1. Very little polymerization reaction in solution occurred when pyrrole concentration was less than 2.5 g·L-1. The pyrrole concentration should reach a higher value to prepare a relatively stable conductive paper with lower resistivity. The XPS results showed that the amount of the PPy coating increased, while the doping level first decreased then increased with the increase of pyrrole concentration. The SEM-EDXA results showed that there was no difference in the amount of PPy coated between the outer surface and the internal wall, but the doping level of the outer surface was higher than that of the internal wall.
  • Researchpp 316-323Zabihzadeh, S. M. (2010). "Water uptake and flexural properties of natural filler/HDPE composites," BioRes. 5(1), 316-323.AbstractPDF
    Composites of flour from different lignocellulosic sources with high-density polyethylene were prepared, and their water absorption and flexural properties were studied. Flour samples from loblolly pine, hybrid Euro-American poplar, and wheat straw were mixed with the polymer at 35 wt % lignocellulosics content and either zero or 2% compatibilizer. Water absorption tests were carried out on injection-molded specimens for temperatures of 30, 45, 60, and 75°C. Results indicated a significant difference among different lignocellulosic types, of which wheat straw composites exhibited the highest and the pine composites showed the lowest water absorption values. The composites with 2% MAPE showed lower water absorption compare to the composites without MAPE. This indicates that the compatibilizer plays an important role to repel the water molecules. For all four temperature conditions, rising temperature increased water absorption significantly. Composites with poplar had the highest flexural strength and modulus. Adding compatibilizer to the composites boosted the flexural properties by improving the adhesion between natural filler and the polymer matrix.
  • Researchpp 324-342Hamdan, S., Talib, Z. A., Rahman, M. R., Ahmed, A. S., and Islam, M. S. (2010). "Dynamic Young's modulus measurement of treated and post-treated tropical wood polymer composites (WPC)," BioRes. 5(1), 324-342.AbstractPDF
    By means of dynamic mechanical thermal analysis (DMTA), selected tropical wood species, namely Eugenia spp., Artocarpus rigidus, Artocarpus elesticus, Koompassia malaccensis, and Xylopia spp. have been characterized. The woods were treated with sodium metaperiodate to convert them into wood polymer composites (WPC). After two weeks the WPC were chemically treated with phenyl hydrazine to convert them into secondary wood polymer composites, also called post-treated WPC (PTWPC). The chemical treatment and post-treatment are successful in improving the mechanical properties of the final product. The storage modulus (E’) was measured using dynamic mechanical thermal analysis (DMTA), and the dynamic Young’s modulus (Ed) was calculated using free-free vibrational testing. The results reveal that the elastic properties i.e. stiffness (Ed) and storage modulus (E’) of the composite were dependent on the type of wood species. The E’ of WPC and PTWPC were much higher than raw wood, whereas the glass transition temperatures (Tg) of WPC and PTWPC were much lower than those of raw wood. Free-free vibration testing provided rapid information about the quality of the composite material, such as the stiffness (Ed) of the PTWPC compared to the respective WPC and raw woods. The WPC and PTWPC were characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). FTIR analysis indicated the absorption band of raw wood at 1635 cm-1 due to carbonyl stretching, whereas WPC and PTWPC showed increased absorption bands near 1718 cm-1 and 1604 cm-1, respectively.
  • Researchpp 343-355Atar, M., Keskin, H., Peker, H., Ustündağ, A., Togay, A., and Candan, Z. (2010). "Impacts of different joint angles and adhesives on diagonal tension performances of box-type furniture," BioRes. 5(1), 343-355.AbstractPDF
    The goal of this study was to determine the effects of different joint angles and adhesives on diagonal tension performances of the box-type furniture made from solid wood and medium density fiberboard (MDF). After drilling joints of 75º, 78º, 81º, 84º, and 87º degrees on Oriental beech, European oak, Scotch pine, and MDF samples, a diagonal tensile test was applied on corners glued with polyvinyl acetate (PVAc) and polyurethane (D-VTKA = Desmodur-Vinyl Trieketonol Acetate) according to ASTM D 1037 standard. With reference to the obtained results, the highest tensile strength was obtained in European oak with PVAc glue and joint angle of 84º, while the lowest value was obtained in MDF with D-VTKA glue and joint angle of 75º. Considering the interaction of wood, adhesive, and joint angle, the highest tensile strength was obtained in European oak with joint angle of 81º and D-VTKA glue (1.089, whereas the lowest tensile strength was determined in MDF with joint angle of 75º and PVAc glue (0.163 Therefore, PVAc as glue and 81º as joint angle could be suggested to obtain some advantageous on the dovetail joint process for box-type furniture made from both solid wood and MDF.
  • Researchpp 356-371Tunc, M. S., Lawoko, M., and van Heiningen, A. (2010). "Understanding the limitations of removal of hemicelluloses during authohydrolysis of a mixture of Southern hardwoods," BioRes. 5(1), 356-371.AbstractPDF
    Extraction of hemicelluloses from wood prior to pulping is being pursued to generate more value-added products, while still producing high quality pulp from the pre-extracted wood. For a better understanding of the factors limiting selective extraction, enzymatic hydrolysis in combination with size exclusion chromatography (SEC) was applied to milled wood and hydrothermally treated wood. Complete dissolution was achieved in a lithium chloride/dimethylacetamide solvent system after mild ball-milling of a Southern Hardwood Mixture (SHM), of SHM extracted using auto-hydrolysis, and of enzyme-treated SHM. SEC tests showed that severe degradation of wood polymers occurred after a milling time of 3 hours. The SEC data also confirmed the presence of lignin-carbohydrate complexes. Based on the results, it is suggested that linkages between lignin and polysaccharides may play an important role in limiting extraction of hemicelluloses.
  • Researchpp 372-388Chand, N., Bajpai, S. K., Joshi, R., and Mary, G. (2010). "Thermomechanical behavior of sisal fibers grafted with poly(acrylamide-co-N-vinyl-2-pyrrolidone) and loaded with silver ions or silver nanoparticles," BioRes. 5(1), 372-388.AbstractPDF
    The graft copolymerization of acrylamide, N-vinyl-2-pyrralidone and N, N’-methylene-bis-acrylamide was carried out to modify the sisal fiber to improve its mechanical and thermal stability. The grafting of poly-(acrylamide-co-N-vinyl-2-pyrrolidone) on sisal fiber surfaces facilitated the loading of Ag(I) ions and Ag(0) nanoparticles. Surface microstructure of the surface modified sisal fiber confirmed the grafting of the copolymer. The XRD and FTIR graphs also showed changes on grafting and on Ag(I) ions and the loading of Ag(0) nanoparticles. It is evident from the DSC curves that the initial thermal stability was improved by delaying the hemicellulose decomposition on grafting and silver ion loading.


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