@article{jones_venditti_park_jameel_koo_2013, title={Enhancement in enzymatic hydrolysis by mechanical refining for pretreated hardwood lignocellulosics}, volume={147}, ISSN={0960-8524}, url={http://dx.doi.org/10.1016/j.biortech.2013.08.030}, DOI={10.1016/j.biortech.2013.08.030}, abstractNote={This study investigated the effectiveness of mechanical refining to overcome the biomass recalcitrance barrier. Laboratory scale refining was conducted via PFI mill and valley beater refiners using green liquor and Kraft hardwood pulps. A strong positive correlation was determined between sugar recovery and water retention value. Refining produced significant improvements in enzymatic hydrolysis yield relative to unrefined substrates (e.g., sugar recovery increase from 67% to 90%, for 15% lignin Kraft pulp). A maximum absolute enzymatic hydrolysis improvement with refining was observed at enzymatic hydrolysis conditions that produced intermediate conversion levels. For a 91% target sugar conversion, PFI refining at 4000 revolutions allowed for a 32% reduction in enzyme charge for 15% lignin content hardwood Kraft pulp and 96 h hydrolysis time, compared to the unrefined material.}, journal={Bioresource Technology}, publisher={Elsevier BV}, author={Jones, Brandon W. and Venditti, Richard and Park, Sunkyu and Jameel, Hasan and Koo, Bonwook}, year={2013}, month={Nov}, pages={353–360} }
 @article{park_lee_koo_park_cosgrove_kim_2013, title={Monitoring Meso-Scale Ordering of Cellulose in Intact Plant Cell Walls Using Sum Frequency Generation Spectroscopy}, volume={163}, ISSN={["1532-2548"]}, DOI={10.1104/pp.113.225235}, abstractNote={Sum frequency generation spectroscopy is sensitive to the ordering of cellulose microfibrils in plant cell walls at the meso scale (nm to μm) that is important for cell wall architecture but cannot be probed by other spectroscopic or diffraction techniques. Sum frequency generation (SFG) vibration spectroscopy can selectively detect crystalline cellulose without spectral interference from cell wall matrix components. Here, we show that the cellulose SFG spectrum is sensitive to cellulose microfibril alignment and packing within the cell wall. SFG intensity at 2,944 cm−1 correlated well with crystalline cellulose contents of various regions of the Arabidopsis (Arabidopsis thaliana) inflorescence, while changes in the 3,320/2,944 cm−1 intensity ratio suggest subtle changes in cellulose ordering as tissues mature. SFG analysis of two cellulose synthase mutants (irx1/cesa8 and irx3/cesa7) indicates a reduction in cellulose content without evidence of altered cellulose structure. In primary cell walls of Arabidopsis, cellulose exhibited a characteristic SFG peak at 2,920 and 3,320 cm−1, whereas in secondary cell walls, it had peaks at 2,944 and 3,320 cm−1. Starch (amylose) gave an SFG peak at 2,904 cm−1 (CH methine) whose intensity increased with light exposure prior to harvest. Selective removal of matrix polysaccharides from primary cell walls by acid hydrolysis resulted in an SFG spectrum resembling that of secondary wall cellulose. Our results show that SFG spectroscopy is sensitive to the ordering of cellulose microfibrils in plant cell walls at the meso scale (nm to μm) that is important for cell wall architecture but cannot be probed by other spectroscopic or diffraction techniques.}, number={2}, journal={PLANT PHYSIOLOGY}, author={Park, Yong Bum and Lee, Christopher M. and Koo, Bon-Wook and Park, Sunkyu and Cosgrove, Daniel J. and Kim, Seong H.}, year={2013}, month={Oct}, pages={907–913} }
 @article{koo_treasure_jameel_phillips_chang_park_2011, title={Reduction of enzyme dosage by oxygen delignification and mechanical refining for enzymatic hydrolysis of green liquor-pretreated hardwood}, volume={165}, DOI={10.1007/s12010-011-9301-4}, abstractNote={In this study, a strategy to reduce enzyme dosage is evaluated by applying two post-treatments, oxygen delignification and mechanical refining. The sugar conversion for GL12 substrates was increased from 51.5% to 77.9% with post-treatments at the enzyme dosage of 10 FPU. When the amount of enzyme was reduced to 5 FPU with post-treatments, the conversion of 71.8% was obtained, which was significant higher than the conversion without any post-treatment using 10 FPU (51.5%). This clearly demonstrates the benefit of post-treatments that allows more than 50% of enzyme reduction at the same level of enzymatic conversion. Enzyme-accessible surface area and pore volume were evaluated by Simons' staining and DSC thermoporometry methods, and strong correlations were found with the sugar conversion.}, number={3-4}, journal={Applied Biochemistry and Biotechnology}, author={Koo, B. W. and Treasure, T. H. and Jameel, H. and Phillips, R. B. and Chang, H. M. and Park, Sunkyu}, year={2011}, pages={832–844} }