@article{xiang_sen_min_savithri_lu_jameel_chiang_chang_2017, title={Field-Grown Transgenic Hybrid Poplar with Modified Lignin Biosynthesis to Improve Enzymatic Saccharification Efficiency}, volume={5}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.6b02740}, abstractNote={Hybrid poplars (Populus nigra L. × Populus maximowiczii A.) were genetically modified through antisense insertion of the 4-coumarate:coenzyme A ligase (4CL) gene. Compositional changes in response to this genetic change were measured in the field after 2 and 3 years of growth. The stem samples were treated with either green liquor or dilute acid pretreatments, representing alkaline and acid pretreatments. The enzymatic saccharification of the untreated and pretreated transgenic poplars were evaluated. After transgenic species were transplanted into the environment, they showed reduced recalcitrance to chemicals (i.e., pretreatments) and enzymes despite their lignin content and S/V ratio being comparable to those of the wild types. Compared to the field-grown poplars, the sugar yield increased up to 103% for untreated transgenic samples and increased 22% for acid- and green liquor-pretreated transgenic samples. This shows that field-grown transgenic hybrid poplars with modified lignin biosynthesis have imp...}, number={3}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Xiang, Zhouyang and Sen, Suman Kumar and Min, Douyong and Savithri, Dhanalekshmi and Lu, Fachuang and Jameel, Hasan and Chiang, Vincent and Chang, Hou-min}, year={2017}, month={Mar}, pages={2407–2414} }
 @article{xiang_sen_roy_min_savithri_jameel_chiang_chang_2015, title={Wood characteristics and enzymatic saccharification efficiency of field-grown transgenic black cottonwood with altered lignin content and structure}, volume={22}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-014-0541-7}, number={1}, journal={CELLULOSE}, author={Xiang, Zhouyang and Sen, Suman Kumar and Roy, Aparna and Min, Douyong and Savithri, Dhanalekshmi and Jameel, Hasan and Chiang, Vincent and Chang, Hou-min}, year={2015}, month={Feb}, pages={683–693} }
 @article{min_xiang_liu_jameel_chiang_jin_chang_2014, title={Improved Protocol for Alkaline Nitrobenzene Oxidation of Woody and Non-Woody Biomass}, volume={35}, ISSN={0277-3813 1532-2319}, url={http://dx.doi.org/10.1080/02773813.2014.902965}, DOI={10.1080/02773813.2014.902965}, abstractNote={The protocol of alkaline nitrobenzene oxidation was investigated to improve its ability to identify the different lignin structures for both woody and non-woody biomass. The survival factors of all six oxidation products—syringaldehde (Sr), vanillin (V), p-hydroxybenzaldehyde (B) and their corresponding acids, syringic acid (Sa), vanillic acid (Va), and p-hydroxybenzoic acid (Ba)—were studied at 170, 180, and 190°C for several residence times. Under similar conditions, various lignin model compounds—a softwood (loblolly pine), a hardwood (red maple), and a non-wood raw material (corn stover)—were oxidized. Molar yields of oxidation products were determined and the ratios of (Sr+Sa)/(V+Va), (Sr/V), and B/(V+Va) (B/V) were calculated. All oxidation products were relatively stable at 170 and 180°C but showed some degradation at 190°C, especially at long residence time. In all cases, p-hydroxybenzoic acid was barely detectable. While yields of oxidation products reach a maximum at 170°C for pine and maple, maximal yields of corn stover require 190°C. Consequently, we recommend that nitrobenzene oxidation be carried out at 170°C for 2.5 h for softwood and hardwood, but at 190°C and 4 h with correction for the survival factors for corn stover and other non-woody biomass. Alternatively, a protocol of oxidation at two temperatures is recommended for non-woody biomass.}, number={1}, journal={Journal of Wood Chemistry and Technology}, publisher={Informa UK Limited}, author={Min, Douyong and Xiang, Zhouyang and Liu, Jie and Jameel, Hasan and Chiang, Vincent and Jin, Yongcan and Chang, Hou-min}, year={2014}, month={Sep}, pages={52–61} }
 @article{min_yang_chiang_jameel_chang_2014, title={The influence of lignin-carbohydrate complexes on the cellulase-mediated saccharification II: Transgenic hybrid poplars (Populus nigra L. and Populus maximowiczii A.)}, volume={116}, ISSN={["1873-7153"]}, DOI={10.1016/j.fuel.2013.07.046}, abstractNote={Twelve transgenic hybrid poplars (Populus nigra L. and Populus maximowiczii A.) were used to demonstrate the influence of the lignin–carbohydrate complexes (LCCs) on enzymatic saccharification. The samples have different levels of the syringaldehyde (S) to vanillin (V) ratio from 0.1 to 2.6 and the lignin content from 10.5% to 24.3%, compared to the control (the S/V ratio 1.7 and the lignin content 22.0%). Any adventitious contaminants that could affect the final enzymatic saccharification were removed by performing thorough extraction on the samples. The crude milled wood lignins were subsequently isolated from which the phenyl glycoside, benzyl ether and γ-ester linkages representative of the LCC were identified and quantified by 13C and 1H–13C HSQC NMR. It was found that the samples showed different levels of the three LCC linkages, depending on the lignin content and/or the S/V ratio. The correlation between the LCCs and enzymatic saccharification nearly conclusively demonstrated that the LCCs accounted for the recalcitrance of lignocellulosic biodegradation.}, journal={FUEL}, author={Min, Dou-yong and Yang, Chenmin and Chiang, Vincent and Jameel, Hasan and Chang, Hou-min}, year={2014}, month={Jan}, pages={56–62} }
 @article{min_jameel_chang_lucia_wang_jin_2014, title={The structural changes of lignin and lignin-carbohydrate complexes in corn stover induced by mild sodium hydroxide treatment}, volume={4}, ISSN={["2046-2069"]}, DOI={10.1039/c3ra47032f}, abstractNote={Non-woody biomass such as corn stover is a very abundant and sustainable biofuel feedstock in the US whose technical hurdles for enzymatic hydrolysis have not been adequately addressed. There is very little useful data on the lignin and the lignin–carbohydrate complexes of corn stover and the impacts of them on bioconversion to fermentable sugars. The following principal tasks were addressed, which will help to develop the roadmap of effective saccharification of corn stover: (1) corn stover was separated into stem, cob, and leaf; (2) lignin (cellulolytic enzyme lignin, CEL) and lignin–carbohydrate complexes (milled wood lignin, MWLc) were isolated from the extractive-free and the alkaline-treated samples, respectively; and (3) the structural changes of lignin and lignin–carbohydrate complexes (LCCs) were characterized by alkaline nitrobenzene oxidation, 13C, and 1H–13C HSQC NMR. The results indicated: (1) a significant amount of p-coumarate and ferulate esters was identified and quantified; (2) lignin of the alkaline-treated sample was more condensed; (3) an unanticipated amount of LCCs was quantified in the extractive-free sample, however, the amount of LCCs decreased significantly with the alkaline treatment. Therefore, lignin and LCCs of the treated sample should be characterized to elucidate their effects on the enzymatic saccharification.}, number={21}, journal={RSC ADVANCES}, author={Min, D. Y. and Jameel, H. and Chang, H. M. and Lucia, L. and Wang, Z. G. and Jin, Y. C.}, year={2014}, pages={10845–10850} }
 @article{min_chang_jameel_lucia_wang_jin_2014, title={The structure of lignin of corn stover and its changes induced by mild sodium hydroxide treatment}, volume={9}, DOI={10.15376/biores.9.2.2405-2414}, abstractNote={Corn stover is an abundant feedstock in the US that can be used for second generation bioethanol production. However, there is little useful data on structure of the lignin of corn stover. The following principal tasks will be addressed to profile the structure of corn stover: (1) separation of corn stover into stem, cob, and leaf; (2) isolation of cellulolytic enzyme lignins (CEL) from extractive-free and the alkali-treated fractions; (3) quantification of p-coumarate and ferulate of fractions by HPLC. The results of alkaline nitrobenzene oxidation and 1H-13C HSQC NMR indicated: (1) the structure of lignin varied in the fractions; (2) a remarkable amount of p-coumarate and ferulate was identified and determined; (3) the remarkable structural changes of lignin induced by alkaline treatment were elucidated.}, number={2}, journal={BioResources}, author={Min, D. Y. and Chang, H. M. and Jameel, H. and Lucia, Lucian and Wang, Z. G. and Jin, Y. C.}, year={2014}, pages={2405–2414} }
 @article{min_li_chiang_jameel_chang_lucia_2014, title={nnThe influence of lignin-carbohydrate complexes on the cellulase-mediated saccharification I: Transgenic black cottonwood (western balsam poplar, California poplar) P-trichocarpa including the xylan down-regulated and the lignin down-regulated lines}, volume={119}, ISSN={["1873-7153"]}, DOI={10.1016/j.fuel.2013.11.047}, abstractNote={The influence of the putative lignin–carbohydrate complexes (LCCs) on enzymatic saccharification was elucidated for the first time by examining two groups of transgenic black cottonwood (P. trichocarpa) comprised of the lignin down-regulated and the xylan down-regulated lines. Any adventitious contaminants that could affect the characterization of LCCs and the enzymatic saccharification were removed by performing a thorough extraction on the samples. The crude milled wood lignin was subsequently isolated from which the phenyl glycoside, benzyl ether and γ-ester linkages representative of the LCCs were identified and quantified with the combination of 13C and 1H–13C Heteronuclear Single Quantum Coherence (HSQC) NMR. The result indicated that the samples showed different levels of the three LCC linkages, depending on the xylan and/or lignin content. The correlation between the LCCs and enzymatic saccharification nearly conclusively demonstrated that the LCCs accounting for the recalcitrance of lignocellulosic biodegradation.}, journal={FUEL}, author={Min, Dou-yong and Li, Quanzi and Chiang, Vincent and Jameel, Hasan and Chang, Hou-min and Lucia, Lucian}, year={2014}, month={Mar}, pages={207–213} }
 @article{min_smith_chang_jameel_2013, title={Influence of isolation condition on structure of milled wood lignin characterized by quantitative c-13 nuclear magnetic resonance spectroscopy}, volume={8}, DOI={10.15376/biores.8.2.1790-1800}, abstractNote={Milled wood lignin (MWL) was widely characterized to demonstrate the structure of native lignin by liquid state 13C NMR. As an isolated lignin, the structure of MWL was influenced by the isolation procedure performed. In this article, hardwood (sweetgum) and softwood (loblolly pine) were subjected to various isolation conditions to elucidate the effect of extracting temperature and milling time on the structure of MWL. Purification was also carried out on the crude MWL. The structure of the crude MWL and the purified MWL was identified and quantified by 13C NMR. Based on the yield and the lignin content of the crude MWL, the optimal isolation was achieved with 8 h milling and 20 °C extracting for hardwood. For softwood, the optimal isolation condition for crude MWL was 12 h milling and 20 °C extracting.}, number={2}, journal={BioResources}, author={Min, D. Y. and Smith, S. W. and Chang, H. M. and Jameel, H.}, year={2013}, pages={1790–1800} }
 @article{min_yang_shi_jameel_chiang_chang_2013, title={The elucidation of the lignin structure effect on the cellulase-mediated saccharification by genetic engineering poplars (Populus nigra L. x Populus maximowiczii A.)}, volume={58}, ISSN={["1873-2909"]}, DOI={10.1016/j.biombioe.2013.08.019}, abstractNote={The lignin structure effect on the recalcitrance of biomass degradation was elucidated by twelve transgenic hybrid poplars (Populus nigra L. and Populus maximowiczii A.). Samples have different levels of the syringaldehyde (S) to vanillin (V) ratio from 0.1 to 2.6 and the lignin content from 10.5 to 24.3%, compared to the control (the S to V ratio 1.7 and the lignin content 22.0%). The dilute acid (0.1% sulfuric acid, 185 °C, and 30 min) and the green liquor (6% total titratable alkali (TTA), 25% sulfidity based on TTA, 185 °C and 15 min) were used as pretreatments. The enzymatic saccharification was performed at 5 FPU g−1 based on the substrate. The removal of lignin and hemicelluloses varied with pretreatments. The high delignification originated from the high S to V ratio. However, the high S to V ratio retarded the enzymatic saccharification. The decrease of the lignin and the hemicelluloses benefited the enzymatic saccharification with or without the pretreatment.}, journal={BIOMASS & BIOENERGY}, author={Min, Douyong and Yang, Chenmin and Shi, Rui and Jameel, Hasan and Chiang, Vincent and Chang, Houmin}, year={2013}, month={Nov}, pages={52–57} }
 @article{min_li_jameel_chiang_chang_2012, title={The Cellulase-Mediated Saccharification on Wood Derived from Transgenic Low-Lignin Lines of Black Cottonwood (Populus trichocarpa)}, volume={168}, ISSN={["1559-0291"]}, DOI={10.1007/s12010-012-9833-2}, abstractNote={Downregulated lignin transgenic black cottonwood (Populus trichocarpa) was used to elucidate the effect of lignin and xylan content on enzymatic saccharification. The lignin contents of three transgenic samples (4CL1-1, 4CL1-4, and CH8-1-4) were 19.3, 16.7, and 15.0 %, respectively, as compared with the wild type (21.3 %). The four pretreatments were dilute acid (0.1 % sulfuric acid, 185 °C, 30 min), green liquor (6 % total titratable alkali, 25 % sulfidity based on TTA, 185 °C, and 15 min.), autohydrolysis (185 °C, 30 min), and ozone delignification (25 °C, 30 min). Following the pretreatment, enzymatic saccharification was carried out using an enzyme charge of 5 FPU/g of substrates. The removal of lignin and hemicellulose varies with both the types of pretreatments and the lignin content of the transgenic trees. Due to the greatest removal of lignin, green liquor induced the highest sugar production and saccharification efficiency, followed by acid, ozone, and autohydrolysis in descending order. The results indicated that lignin is the main recalcitrance of biomass degradation. At a given lignin content, pretreatment with ozone delignification had lower saccharification efficiency than the other pretreatment methods due to higher xylan content.}, number={4}, journal={APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY}, author={Min, Douyong and Li, Quanzi and Jameel, Hasan and Chiang, Vincent and Chang, Hou-min}, year={2012}, month={Oct}, pages={947–955} }
 @inproceedings{min_li_yang_chang_chiang_jameel_2012, title={The effects of transgenic samples on the enzymatic saccharification}, booktitle={Proceeding of the 4th International Conference on Pulping, Papermaking and Biotechnology (ICPPB '12), vols. I and II}, author={Min, D. Y. and Li, Q. Z. and Yang, C. M. and Chang, H. M. and Chiang, V. and Jameel, H.}, year={2012}, pages={1058–1062} }
 @article{min_jameel_chiang_chang_2012, title={effect of lignin on enzymatic saccharification of hardwood after green liquor and sulfuric acid pretreatments}, volume={7}, DOI={10.15376/biores.7.2.2272-2283}, abstractNote={Red maple, sweet gum, trembling aspen, red alder, and Eucalyptus globulus samples were pretreated with dilute sulfuric acid and green liquor before enzymatic saccharification. Substrates showed different levels of delignification and sugar recovery, depending on the applied pretreatments and the syringaldehyde/vanillin ratio (S/V). Three major conclusions were drawn in this research. First, lignin is the greatest contributor to recalcitrance of hardwood to enzymatic saccharification. Second, a high S/V ratio is a useful indicator of high delignification during a pretreatment process. Third, green liquor pretreatment is a promising pretreatment method because of a high delignification degree and sugar recovery. In addition, xylan also contributes to the recalcitrance of hardwoods toward enzymatic saccharification.}, number={2}, journal={BioResources}, author={Min, D. Y. and Jameel, H. and Chiang, V. and Chang, H. M.}, year={2012}, pages={2272–2283} }
 @article{min_li_jameel_chiang_chang_2011, title={Comparison of pretreatment protocols for cellulase-mediated saccharification of wood derived from transgenic low-xylan lines of cottonwood (P. trichocarpa)}, volume={35}, ISSN={["1873-2909"]}, DOI={10.1016/j.biombioe.2011.04.034}, abstractNote={The novel low xylan content transgenic cottonwood (P. trichocarpa) was used to elucidate recalcitrance of enzymatic saccharification with or without four different pretreatment methods. The xylan contents of two transgenic samples (8Di3 and 8Di5) were 11.4% and 11.7%, respectively, as compared with the wild type (16.0%). Contrarily, the lignin contents of two transgenic samples were 23.1% and 24.5%, respectively, as compared with the wild type (20.8%). The four pretreatments were dilute acid (0.1% sulfuric acid, 185 °C, 30 min), green liquor (6% total titratable alkali (TTA), 25% sulfidity based on TTA, 185 °C and 15 min), auto hydrolysis (185 °C, 30 min) and ozone delignification (25 °C, 30 min). Following the pretreatment, enzymatic saccharification was carried out using three enzyme charges of 10, 20 and 30 FPU per gram of substrate. The removal of lignin and hemicelluloses varied with the type of pretreatment and with the lignin content of the transgenic trees. High lignin content implied low enzymatic saccharification. Low xylan content native substrates lead to high enzymatic saccharification. High S to V (sryingaldehyde to vanillin) ratio substrates had high delignification during pretreatment. Compared to the wild type, the transgenics were better choice as feed stocks due to higher enzymatic saccharification without pretreatment which mean low the cost of bio-ethanol. Compared to three pretreatment methods, the green liquor pretreatment greatly improves the conversion of polysaccharides in general.}, number={8}, journal={BIOMASS & BIOENERGY}, author={Min, Douyong and Li, Quanzi and Jameel, Hasan and Chiang, Vincent and Chang, Hou-min}, year={2011}, month={Aug}, pages={3514–3521} }
 @article{li_min_wang_peszlen_horvath_horvath_nishimura_jameel_chang_chiang_2011, title={Down-regulation of glycosyltransferase 8D genes in Populus trichocarpa caused reduced mechanical strength and xylan content in wood}, volume={31}, ISSN={["1758-4469"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79953831391&partnerID=MN8TOARS}, DOI={10.1093/treephys/tpr008}, abstractNote={Members of glycosyltransferase protein families GT8, GT43 and GT47 are implicated in the biosynthesis of xylan in the secondary cell walls of Arabidopsis. The Arabidopsis mutant irx8 has a 60% reduction in xylan. However, over-expression of an ortholog of Arabidopsis IRX8, poplar PoGT8D, in Arabidopsis irx8 mutant could not restore xylan synthesis. The functions of tree GT8D genes remain unclear. We identified two GT8 gene homologs, PtrGT8D1 and PtrGT8D2, in Populus trichocarpa. They are the only two GT8D members and are abundantly and specifically expressed in the differentiating xylem of P. trichocarpa. PtrGT8D1 transcript abundance was >7 times that of PtrGT8D2. To elucidate the genetic function of GT8D in P. trichocarpa, the expression of PtrGT8D1 and PtrGT8D2 was simultaneously knocked down through RNAi. Four transgenic lines had 85-94% reduction in transcripts of PtrGT8D1 and PtrGT8D2, resulting in 29-36% reduction in stem wood xylan content. Xylan reduction had essentially no effect on cellulose quantity but caused an 11-25% increase in lignin. These transgenics exhibit a brittle wood phenotype, accompanied by increased vessel diameter and thinner fiber cell walls in stem xylem. Stem modulus of elasticity and modulus of rupture were reduced by 17-29% and 16-23%, respectively, and were positively correlated with xylan content but negatively correlated with lignin quantity. These results suggest that PtrGT8Ds play key roles in xylan biosynthesis in wood. Xylan may be a more important factor than lignin affecting the stiffness and fracture strength of wood.}, number={2}, journal={TREE PHYSIOLOGY}, publisher={Oxford University Press (OUP)}, author={Li, Quanzi and Min, Douyong and Wang, Jack Peng-Yu and Peszlen, Ilona and Horvath, Laszlo and Horvath, Balazs and Nishimura, Yufuko and Jameel, Hasan and Chang, Hou-Min and Chiang, Vincent L.}, year={2011}, month={Feb}, pages={226–236} }
 @article{min_li_shen_lin_2010, title={Research and synthesis of organosilicon nonthrombogenic materials containing sulfobetaine group}, volume={79}, number={2}, journal={Colloids and Surfaces. B, Biointerfaces}, author={Min, D. Y. and Li, Z. Z. and Shen, J. A. and Lin, S. C.}, year={2010}, pages={415–420} }