@article{hu_du_liu_chang_jameel_2016, title={Structural Characterization of Pine Kraft Lignin: BioChoice Lignin vs Indulin AT}, volume={36}, ISSN={["1532-2319"]}, DOI={10.1080/02773813.2016.1214732}, abstractNote={BioChoice lignin (BCL) is a newly commercialized pine kraft lignin from Plymouth Mill of Domtar, which is precipitated from black liquor of bleachable-grade pulp. Indulin AT is a pine kraft lignin commercialized by Meadwestvaco for the past 60 years, which is precipitated from black liquor of linerboard-grade pulp. Thus, the two technical lignins are produced under quite different conditions in terms of alkali charge and pulping time/temperature. While the chemical structure of Indulin AT is well documented, that of BCL is totally unknown. In this study, chemical structures of BCL and Indulin AT are characterized using modern analytical techniques and compared with those of pine milled wood lignin (MWL) in order to elucidate the structural changes that occur during kraft pulping and the structural differences, if any, between BCL and Indulin AT. Both BCL and Indulin AT are structurally very different from the native lignin (MWL) in wood, indicating drastic structural modification during the kraft pulping process. Surprisingly, BCL and Indulin AT are structurally very similar, in spite of the fact that they are produced under different process conditions. However, there are subtle structural differences between BCL and Indulin AT. BCL has higher phenolic hydroxyl, catechol, enol ether, and stilbene contents, but lower methoxyl and β-O-4 contents. These differences are explained by the different pulping conditions under which the two technical lignins are produced.}, number={6}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={Hu, Zhoujian and Du, Xueyu and Liu, Jie and Chang, Hou-min and Jameel, Hasan}, year={2016}, pages={432–446} }
 @article{chen_hu_chang_li_2007, title={Micro analytical methods for determination of compression wood content in loblolly pine}, volume={27}, ISSN={["1532-2319"]}, DOI={10.1080/02773810701700810}, abstractNote={Abstract All loblolly pine trees, especially the juvenile portion, contain various amounts of compression wood. The morphological, chemical, and papermaking properties of compression wood are distinctively different from those of normal juvenile wood and mature wood. Compression wood has higher lignin and galactan, but lower cellulose and mannan content, shorter average fiber length, lower fiber width but thicker cell wall, higher fiber coarseness and higher microfibril angles as compared with the corresponding normal wood. Micro analytical methods have been developed to quantitatively determine the percentage of compression wood in an incremental core so as to eliminate the effects of compression wood on the aforementioned properties. This enables accurate quantitative genetic analyses of these properties for tree breeding programs.}, number={3-4}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={Chen, Qing-min and Hu, Zhoujian and Chang, Hou-min and Li, Bailian}, year={2007}, pages={169–178} }
 @article{hu_yeh_chang_matsumoto_kadla_2006, title={Elucidation of the structure of cellulolytic enzyme lignin}, volume={60}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2006.061}, abstractNote={Abstract
            Cellulolytic enzyme lignin (CEL) and milled wood lignin (MWL) were prepared by three different ball-milling methods. The structure of CEL at various yields was elucidated and compared with MWL using wet chemical analysis, FTIR and solution-state NMR techniques. Results show that ball milling of wood degrades β-O-4 structures in lignin. However, even after extensive ball milling, less than 25% of the β-O-4 structures were degraded. The extent of degradation was less for softwood than for hardwood lignin. Extractable lignin yield, either MWL or CEL, was the best way to assess the extent and effect of ball milling. CEL is preferred over MWL, as it can be isolated in higher yield with less degradation. CEL was isolated at yields ranging from 20% to 86%. Over this range the CEL had similar structures, suggesting that lignin in the secondary wall is uniform in structure. The residual enzyme lignin (REL) was structurally different from CEL and may originate mainly from the middle lamella. In this paper we propose a new procedure for the isolation of lignin for use in structural studies, whereby wood is sufficiently milled and successively extracted to produce three lignin fractions representing the total lignin in wood.}, number={4}, journal={HOLZFORSCHUNG}, author={Hu, Zhoujian and Yeh, Ting-Feng and Chang, Hou-min and Matsumoto, Yuji and Kadla, John F.}, year={2006}, month={Jul}, pages={389–397} }