@article{argyropoulos_crestini_dahlstrand_furusjo_gioia_jedvert_henriksson_hulteberg_lawoko_pierrou_et al._2023, title={Kraft Lignin: A Valuable, Sustainable Resource, Opportunities and Challenges}, volume={9}, ISSN={["1864-564X"]}, DOI={10.1002/cssc.202300492}, abstractNote={Abstract Kraft lignin, a by‐product from the production of pulp, is currently incinerated in the recovery boiler during the chemical recovery cycle, generating valuable bioenergy and recycling inorganic chemicals to the pulping process operation. Removing lignin from the black liquor or its gasification lowers the recovery boiler load enabling increased pulp production. During the past ten years, lignin separation technologies have emerged and the interest of the research community to valorize this underutilized resource has been invigorated. The aim of this Review is to give (1) a dedicated overview of the kraft process with a focus on the lignin, (2) an overview of applications that are being developed, and (3) a techno‐economic and life cycle asseeements of value chains from black liquor to different products. Overall, it is anticipated that this effort will inspire further work for developing and using kraft lignin as a commodity raw material for new applications undeniably promoting pivotal global sustainability concerns.}, journal={CHEMSUSCHEM}, author={Argyropoulos, Dimitris D. S. and Crestini, Claudia and Dahlstrand, Christian and Furusjo, Erik and Gioia, Claudio and Jedvert, Kerstin and Henriksson, Gunnar and Hulteberg, Christian and Lawoko, Martin and Pierrou, Clara and et al.}, year={2023}, month={Sep} }
 @article{sarder_piner_rios_chacon_artner_barrios_argyropoulos_2022, title={Copolymers of starch, a sustainable template for biomedical applications: A review}, volume={12}, url={http://dx.doi.org/10.1016/j.carbpol.2021.118973}, DOI={10.1016/j.carbpol.2021.118973}, abstractNote={The outstanding versatility of starch offers a source of inspiration for the development of high-performance-value-added biomaterials for the biomedical field, including drug delivery, tissue engineering and diagnostic imaging. This is because starch-based materials can be tailored to specific applications via facile grafting or other chemistries, introducing specific substituents, with starch being effectively the "template" used in all the chemical transformations discussed in this review. A considerable effort has been carried out to obtain specific tailored starch-based grafted polymers, taking advantage of its biocompatibility and biodegradability with appealing sustainability considerations. The aim of this review is to critically explore the latest research that use grafting chemistries on starch for the synthesis of products for biomedical applications. An effort is made in reviewing the literature that proposes synthetic "greener" approaches, the use of enzymes and their immobilized analogues and alternative solvent systems, including water emulsions, ionic liquids and supercritical CO2.}, journal={CARBOHYDRATE POLYMERS}, publisher={Elsevier BV}, author={Sarder, Roman and Piner, Emily and Rios, David Cruz and Chacon, Lisandra and Artner, Mirela Angelita and Barrios, Nelson and Argyropoulos, Dimitris}, year={2022}, month={Feb}, pages={118973} }
 @misc{gaynor_szlek_kwon_tiller_byington_argyropoulos_2022, title={Lignin Use in Nonwovens: A Review}, volume={17}, ISSN={["1930-2126"]}, DOI={10.15376/biores.17.2.Gaynor}, abstractNote={While lignin has been gaining wide research interest for a variety of applications across many industries, relatively little work has been published on its applications in nonwovens. Consequently, this article offers an overview of the underlying principles and both the present and future applications of lignin within the nonwoven industry. Due to the distinct structure of lignin, processing, fiber production, composites with polymers, dye dispersant, and fire-retardant applications are all unique opportunities for lignin application in nonwovens discussed in this review. Conventional nonwoven processing techniques, such as electrospinning, have been reported to successfully produce lignin-based nonwovens, specifically lignin/polymer composite nonwovens. This account points to pivotal polymer matrix/lignin composite compatibility issues that define various processing technologies. However, lignin use is not limited to incorporation within nonwoven fibers mats and is currently used in dye dispersion with the potential of phase out petroleum-based dye dispersants. Finally, the high phenolic content of lignin endows it with fire-retardant and antimicrobial properties, among others, that present additional opportunities for lignin in the nonwoven industry. Throughout this review, an effort is made to outline the advantages and challenges of using lignin as a green and sustainable ingredient for the production of nonwoven materials.}, number={2}, journal={BIORESOURCES}, author={Gaynor, J. Gavin and Szlek, Dorota B. and Kwon, Soojin and Tiller, Phoenix S. and Byington, Matthew S. and Argyropoulos, Dimitris S.}, year={2022}, month={May}, pages={3445–3488} }
 @article{more_elder_pajer_argyropoulos_jiang_2022, title={Novel and Integrated Process for the Valorization of Kraft Lignin to Produce Lignin-Containing Vitrimers}, volume={12}, ISSN={["2470-1343"]}, DOI={10.1021/acsomega.2c06445}, abstractNote={The valorization of lignin into value-added products by oxidative conversion is a widely studied strategy. However, in many cases, this approach has limited scope for integration into industrial processes. The objective of our work is to maximize overall lignin utilization to produce diverse value-added products with a focus on integration in the existing industrial pulp and paper processes. The utilization of the sequential oxidation strategy using oxygen and ozone resulted in kraft lignin with a marked improvement in carboxyl content and also allowed the formation of vanillin and vanillic acid in the oxygen stage. The sequentially oxidized lignin (OxL-COOH) was then cured with poly(ethylene glycol) diglycidyl ether (PEG-epoxy) to form high-lignin-content (>48 wt %) vitrimers with high thermal stability, fast relaxation, swelling, and self-healing due to the presence of bond-exchangeable cross-linked networks. Overall, this study provides a novel approach for the multidimensional valorization of lignin and demonstrates an integrated approach for kraft lignin valorization in the pulp and paper industry.}, journal={ACS OMEGA}, author={More, Ajinkya and Elder, Thomas and Pajer, Nicolo and Argyropoulos, Dimitris S. and Jiang, Zhihua}, year={2022}, month={Dec} }
 @misc{kropat_liao_park_salem_johnson_argyropoulos_2021, title={A Perspective of Lignin Processing and Utilization Technologies for Composites and Plastics with Emphasis on Technical and Market Trends}, volume={16}, ISSN={["1930-2126"]}, DOI={10.15376/biores.16.1.Kropat}, abstractNote={This effort is focused on work completed publicly and privately within academic research and industrial sectors on the utilization of lignin to produce thermosets, thermoplastics, foams, hydrogels, and rubbers. The size of the plastics market and the current and projected influence of lignin on it were evaluated. Further, an analysis of patent activity was employed to show the direction of and interest for lignin in these markets. The market trends documented in the literature, when coupled with detailed patent research, offer a new approach to evaluate potential markets and future directions. The analysis of the commercial market sizes of bioplastics and segmentation showed low penetration of actual lignin-based bioplastics. This exposed the contradiction between the abundance of technologies for lignin-based materials and their little practical use. In addition, this finding highlighted a severe gap between lignin research and development and the actual market.}, number={1}, journal={BIORESOURCES}, author={Kropat, Marcel and Liao, Mochen and Park, Hyeonji and Salem, Khandoker S. and Johnson, Shelly and Argyropoulos, Dimitris S.}, year={2021}, month={Feb}, pages={2084–2115} }
 @article{argyropoulos_pajer_crestini_2021, title={Quantitative P-31 NMR Analysis of Lignins and Tannins}, volume={8}, ISSN={["1940-087X"]}, DOI={10.3791/62696}, abstractNote={The development of sustainable biorefinery products is confronted, among others, with the challenge of lignin and tannin valorization. These abundant, renewable aromatic biopolymers have not been widely exploited due to their inherent structural complexity and high degrees of variability and species diversity. The lack of a defined primary structure for these polyphenols is further compounded with complex chemical alterations induced during processing, eventually imparting a large variety of structural features of extreme significance for any further utilization efforts. Consequently, a protocol for the rapid, simple, and unequivocal identification and quantification of the various functional groups present in natural polyphenols, is a fundamental prerequisite for understanding and accordingly tailor their reactivity and eventual utility. Quantitative 31P NMR offers the opportunity to rapidly and reliably identify unsubstituted, o-mono substituted, and o-disubstituted phenols, aliphatic OHs, and carboxylic acid moieties in lignins and tannins with broad application potential. The methodology consists of an in situ quantitative lignin or tannin labeling procedure using a suitable 31P containing probe, followed by the acquisition of a quantitative 31P NMR spectrum in the presence of an internal standard. The high natural abundance of the 31P nucleus allows for small amounts of the sample (~30 mg) and short NMR acquisition times (~30-120 min) with well-resolved 31P signals that are highly dependent on the surrounding chemical environment of the labeled OH groups.}, number={174}, journal={JOVE-JOURNAL OF VISUALIZED EXPERIMENTS}, author={Argyropoulos, Dimitris S. and Pajer, Nicolo and Crestini, Claudia}, year={2021}, month={Aug} }
 @article{agate_argyropoulos_jameel_lucia_pal_2020, title={3D Photoinduced Spatiotemporal Resolution of Cellulose-Based Hydrogels for Fabrication of Biomedical Devices}, volume={3}, ISSN={["2576-6422"]}, url={https://doi.org/10.1021/acsabm.0c00517}, DOI={10.1021/acsabm.0c00517}, abstractNote={Rational spatiotemporal irradiation of cellulose-based hydrogels (carboxymethylcellulose (CMC), citric acid, and riboflavin) using a laser diode stereolithography 3D printer obtained architectures referred to as photodegradation addressable hydrogels (PAHs). Under irradiation, these PAHs engage in an unprecedented spatially resolved zonal swelling illustrating marked but controllable changes in swelling and thickness while concomitantly obtaining improved oxygen transmission rate values by 5 times. XPS, carboxyl content, and swelling data comparisons of hydrogel formulations show that photodegradation and ablation of the material occur, where hydroxyl sites of CMC are converted to aldehydes and ketones. XRD data show that the total number of crystalline aggregates in the material are lowered after photoablation. The spatially tuned (photoablated) hydrogel films can thus be shaped into a lens form. The energy required for the lens tuning process can be lowered up to 30 times by incorporation of riboflavin in the films. The method demonstrated here enables the processing of a material that is difficult to be machined or cast by popular contact lens making methods.}, number={8}, journal={ACS APPLIED BIO MATERIALS}, publisher={American Chemical Society (ACS)}, author={Agate, Sachin and Argyropoulos, Dimitris S. and Jameel, Hasan and Lucia, Lucian and Pal, Lokendra}, year={2020}, month={Aug}, pages={5007–5019} }
 @article{alvarado_argyropoulos_scholle_peddinti_ghiladi_2019, title={A facile strategy for photoactive nanocellulose-based antimicrobial materials}, volume={21}, ISSN={1463-9262 1463-9270}, url={http://dx.doi.org/10.1039/C9GC00551J}, DOI={10.1039/c9gc00551j}, abstractNote={Anti-infective materials based upon renewable nanocellulose–porphyrin conjugates photodynamically inactivated four strains of drug-resistant bacteria and two viruses by 99.999+%.}, number={12}, journal={Green Chemistry}, publisher={Royal Society of Chemistry (RSC)}, author={Alvarado, David Ramirez and Argyropoulos, Dimitris S. and Scholle, Frank and Peddinti, Bharadwaja S. T. and Ghiladi, Reza A.}, year={2019}, pages={3424–3435} }
 @article{sagues_jain_brown_aggarwal_suarez_kollman_park_argyropoulos_2019, title={Are lignin-derived carbon fibers graphitic enough?}, volume={21}, ISSN={1463-9262 1463-9270}, url={http://dx.doi.org/10.1039/C9GC01806A}, DOI={10.1039/C9GC01806A}, abstractNote={The extent of graphitization is an overlooked limitation to lignin-derived carbon fiber development.}, number={16}, journal={Green Chemistry}, publisher={Royal Society of Chemistry (RSC)}, author={Sagues, William J. and Jain, Ankush and Brown, Dylan and Aggarwal, Salonika and Suarez, Antonio and Kollman, Matthew and Park, Seonghyun and Argyropoulos, Dimitris S.}, year={2019}, pages={4253–4265} }
 @article{meng_crestini_ben_hao_pu_ragauskas_argyropoulos_2019, title={Determination of hydroxyl groups in biorefinery resources via quantitative 31P NMR spectroscopy}, volume={14}, ISSN={1754-2189 1750-2799}, url={http://dx.doi.org/10.1038/s41596-019-0191-1}, DOI={10.1038/s41596-019-0191-1}, abstractNote={The analysis of chemical structural characteristics of biorefinery product streams (such as lignin and tannin) has advanced substantially over the past decade, with traditional wet-chemical techniques being replaced or supplemented by NMR methodologies. Quantitative 31P NMR spectroscopy is a promising technique for the analysis of hydroxyl groups because of its unique characterization capability and broad potential applicability across the biorefinery research community. This protocol describes procedures for (i) the preparation/solubilization of lignin and tannin, (ii) the phosphitylation of their hydroxyl groups, (iii) NMR acquisition details, and (iv) the ensuing data analyses and means to precisely calculate the content of the different types of hydroxyl groups. Compared with traditional wet-chemical techniques, the technique of quantitative 31P NMR spectroscopy offers unique advantages in measuring hydroxyl groups in a single spectrum with high signal resolution. The method provides complete quantitative information about the hydroxyl groups with small amounts of sample (~30 mg) within a relatively short experimental time (~30-120 min).}, number={9}, journal={Nature Protocols}, publisher={Springer Science and Business Media LLC}, author={Meng, Xianzhi and Crestini, Claudia and Ben, Haoxi and Hao, Naijia and Pu, Yunqiao and Ragauskas, Arthur J. and Argyropoulos, Dimitris S.}, year={2019}, month={Aug}, pages={2627–2647} }
 @article{zhang_zhu_sun_yuan_cheng_argyropoulos_2019, title={Extraction and characterization of lignin from corncob residue after acid-catalyzed steam explosion pretreatment}, volume={133}, ISSN={["1872-633X"]}, url={https://doi.org/10.1016/j.indcrop.2019.03.027}, DOI={10.1016/j.indcrop.2019.03.027}, abstractNote={Abstract Corncob residue after acid catalyzed steam explosion (CRSE) is rich in cellulose and lignin. However, the structure of the lignin present in the CRSE has not been studied in detail and this hinders its application. An enzymatic mild acidolysis lignin (EMAL) extraction is adopted to process the CRSE where the extraction conditions are modified to improve lignin recovery and purity. Extraction severity factor is calculated and correlations between it and lignin recovery, lignin purity and total phenolic groups are evaluated. The best extraction condition produces lignin with a purity of 99.0% and a yield of 57.3%. A comparative study between lignin samples extracted under the best condition from the CRSE and untreated corncob (CC) is conducted. The structures of extracted lignin samples are investigated by using 31P NMR, 2D-HSQC NMR, FTIR and GPC. Although SE pretreatment caused degradation of lignin, the abundance per 100 aromatic units of β-O-4′ linkages is 46.0, which is higher than most technical lignins. The molecular weight of CRSE EMAL is found to be higher than that of CC EMAL due to condensation reactions. Antioxidant property of CC EMAL and CRSE EMAL is measured and compared. The data shows that CRSE EMAL possesses better antioxidant activity (IC50 = 128 μg/mL) than CC EMAL (IC50 = 238 μg/mL), which makes CRSE EMAL an ideal additive for polymer composites.}, journal={INDUSTRIAL CROPS AND PRODUCTS}, publisher={Elsevier BV}, author={Zhang, Xin and Zhu, Jiadeng and Sun, Lu and Yuan, Qipeng and Cheng, Gang and Argyropoulos, Dimitris S.}, year={2019}, month={Jul}, pages={241–249} }
 @article{pupier_nuzillard_wist_schlörer_kuhn_erdelyi_steinbeck_williams_butts_claridge_et al._2018, title={NMReDATA, a standard to report the NMR assignment and parameters of organic compounds}, volume={56}, ISSN={0749-1581}, url={http://dx.doi.org/10.1002/MRC.4737}, DOI={10.1002/MRC.4737}, abstractNote={Even though NMR has found countless applications in the field of small molecule characterization, there is no standard file format available for the NMR data relevant to structure characterization of small molecules. A new format is therefore introduced to associate the NMR parameters extracted from 1D and 2D spectra of organic compounds to the proposed chemical structure. These NMR parameters, which we shall call NMReDATA (for nuclear magnetic resonance extracted data), include chemical shift values, signal integrals, intensities, multiplicities, scalar coupling constants, lists of 2D correlations, relaxation times, and diffusion rates. The file format is an extension of the existing Structure Data Format, which is compatible with the commonly used MOL format. The association of an NMReDATA file with the raw and spectral data from which it originates constitutes an NMR record. This format is easily readable by humans and computers and provides a simple and efficient way for disseminating results of structural chemistry investigations, allowing automatic verification of published results, and for assisting the constitution of highly needed open-source structural databases.}, number={8}, journal={Magnetic Resonance in Chemistry}, publisher={Wiley}, author={Pupier, Marion and Nuzillard, Jean-Marc and Wist, Julien and Schlörer, Nils E. and Kuhn, Stefan and Erdelyi, Mate and Steinbeck, Christoph and Williams, Antony J. and Butts, Craig and Claridge, Tim D.W. and et al.}, year={2018}, month={May}, pages={703–715} }
 @article{sabbaghan_argyropoulos_2018, title={Synthesis and characterization of nano fibrillated cellulose/Cu2O films; micro and nano particle nucleation effects}, volume={197}, ISSN={["1879-1344"]}, url={https://doi.org/10.1016/j.carbpol.2018.06.011}, DOI={10.1016/j.carbpol.2018.06.011}, abstractNote={Cubic, truncated cubic and spherical nano and micro particles of Cu2O, can be selectively deposited onto nano fibrilated cellulose gels by the modulated alkaline reduction of Cu2+ ions aided by the cellulose’s reducing end groups. The role of the cellulose’s reducing end groups and that of externally added carbohydrate reducing agents, towards inducing various Cu2O morphologies, is discussed with respect to the detailed nucleation effects leading to micro and nano Cu2O particle deposition on NFC. When the reducing end groups are provided only by the cellulose’s chain ends, supersaturation effects seem to be affecting the Cu2O nucleation mechanism. However, the Cu2O nucleation considerations were altered when mobile reducing end groups were provided by adding dextrose in the system, promoting additional particle nucleation sites. Furthermore, the effort offered the possibility to quantitatively determine the number of accessible reducing end groups (-CHO) present in NFC, expressed in mmol/g. The optical properties of the created NFC/Cu2O films were examined by UV–vis absorption measurements, revealing band gaps ranging between 2.02–2.25 eV. The accumulated understanding expands the utility window and opens new directions for the novel utilization of nano-fibrillated cellulose, and more specifically toward semiconductor applications.}, journal={CARBOHYDRATE POLYMERS}, publisher={Elsevier BV}, author={Sabbaghan, Maryam and Argyropoulos, Dimitris S.}, year={2018}, month={Oct}, pages={614–622} }
 @article{sanaeishoar_sabbaghan_argyropoulos_2018, title={Ultrasound assisted polyacrylamide grafting on nano-fibrillated cellulose}, volume={181}, ISSN={0144-8617}, url={http://dx.doi.org/10.1016/J.CARBPOL.2017.11.042}, DOI={10.1016/J.CARBPOL.2017.11.042}, abstractNote={Polyacrylamide has been grafted onto nanofibrillated cellulose (NFC-g-PAM) under mild conditions. This was accomplished by developing and optimizing an ultrasound assisted protocol in the presence of potassium persulfate initiator. The synthesis was optimized on the basis of maximizing grafting percentage and grafting efficiency by varying the initiator and monomer concentration. The data shows that ultrasound has a profound effect in promoting the grafting of PAM onto NFC. The intended grafting was confirmed and the properties of the new co-polymers were examined by elemental analyses, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Intrinsic viscosity determinations in 0.1 M cupriethylenediamine solutions for the NFC-g-PAM copolymers and the starting NFC and PAM homopolymer revealed that grafting of PAM onto nanofibrillated cellulose has a profound effect on the hydrodynamic characteristics of the graft polymers.}, journal={Carbohydrate Polymers}, publisher={Elsevier BV}, author={Sanaeishoar, Haleh and Sabbaghan, Maryam and Argyropoulos, Dimitris S.}, year={2018}, month={Feb}, pages={1071–1077} }
 @article{bitter_clark_rothenberg_matharu_crestini_argyropoulos_cabrera-rodríguez_dale_stevens_marrocchi_et al._2017, title={Bio-based chemicals: general discussion}, volume={202}, url={https://doi.org/10.1039/C7FD90048A}, DOI={10.1039/C7FD90048A}, journal={Faraday Discussions}, publisher={Royal Society of Chemistry (RSC)}, author={Bitter, Harry and Clark, James and Rothenberg, Gadi and Matharu, Avtar and Crestini, Claudia and Argyropoulos, Dimitris and Cabrera-Rodríguez, Carlos I. and Dale, Bruce E. and Stevens, Christian and Marrocchi, Assunta and et al.}, year={2017}, pages={227–245} }
 @article{huber_argyropoulos_matharu_bitter_stevens_herou_wilson_clark_pant_cabrera-rodríguez_et al._2017, title={Bio-based materials: general discussion}, volume={202}, url={https://doi.org/10.1039/C7FD90047C}, DOI={10.1039/C7FD90047C}, abstractNote={The first page of this article is displayed as the abstract.}, journal={Faraday Discussions}, publisher={Royal Society of Chemistry (RSC)}, author={Huber, George and Argyropoulos, Dimitris and Matharu, Avtar and Bitter, Harry and Stevens, Christian and Herou, Servann and Wilson, Karen and Clark, James and Pant, Deepak and Cabrera-Rodríguez, Carlos I. and et al.}, year={2017}, pages={121–139} }
 @article{argyropoulos_bitter_brandt-talbot_budarin_chesi_clark_coma_crestini_dale_graca_et al._2017, title={Conversion technologies: general discussion}, volume={202}, url={https://doi.org/10.1039/C7FD90049J}, DOI={10.1039/C7FD90049J}, abstractNote={The first page of this article is displayed as the abstract.}, journal={Faraday Discussions}, publisher={Royal Society of Chemistry (RSC)}, author={Argyropoulos, Dimitris and Bitter, Harry and Brandt-Talbot, Agnieszka and Budarin, Vitaliy and Chesi, Claudio and Clark, James and Coma, Marta and Crestini, Claudia and Dale, Bruce and Graca, Ines and et al.}, year={2017}, pages={371–389} }
 @article{leskinen_kelley_argyropoulos_2017, title={E-beam irradiation & steam explosion as biomass pretreatment, and the complex role of lignin in substrate recalcitrance}, volume={103}, ISSN={0961-9534}, url={http://dx.doi.org/10.1016/j.biombioe.2017.05.008}, DOI={10.1016/j.biombioe.2017.05.008}, abstractNote={Abstract Sequential electron beam-steam explosion (EB-SE) pretreatment was applied to hardwood (Birch) and softwood (Pine) substrates in an effort to enhance their enzymatic saccharification. The effect of these two pretreatments on the structure and composition of the individual cell wall components was examined. The combination of these treatments showed a synergistic effect on the conversion of hemicelluloses into water soluble oligomers, and enhanced the overall enzymatic saccharification of wood substrates. Even after the combined pretreatment Pine was more recalcitrant than Birch, which was attributed to differences in the lignin. Model systems created from cellulose and isolated high molecular weight (HMW) lignin fractions were found to inhibit enzymatic conversion of cellulose by 20% over a control. This inhibition is likely related to the unproductive binding of the cellulose enzymes to the HMW lignin. Additionally, the presence of the HMW lignin reduces the swelling capacity of the wood substrate, and thus its accessibility to enzymes. Conversely, low molecular weight lignin fragments were found to be slightly beneficial for enzymatic hydrolysis of cellulose substrates. These results provide insight to the complex interactions between lignin and cellulase enzymes, and highlight the need for pretreatment processes that can effectively cleave lignin into oligomeric fragments.}, journal={Biomass and Bioenergy}, publisher={Elsevier BV}, author={Leskinen, Timo and Kelley, Stephen S. and Argyropoulos, Dimitris S.}, year={2017}, month={Aug}, pages={21–28} }
 @article{aldous_argyropoulos_budarin_cabrera-rodríguez_clark_coma_constable_fan_gschwend_hayes_et al._2017, title={Feedstocks and analysis: general discussion}, volume={202}, url={https://doi.org/10.1039/C7FD90050C}, DOI={10.1039/C7FD90050C}, journal={Faraday Discussions}, publisher={Royal Society of Chemistry (RSC)}, author={Aldous, Leigh and Argyropoulos, Dimitris and Budarin, Vitaliy and Cabrera-Rodríguez, Carlos I. and Clark, James and Coma, Marta and Constable, David and Fan, Jiajun and Gschwend, Florence and Hayes, Daniel and et al.}, year={2017}, pages={497–519} }
 @article{crestini_lange_sette_argyropoulos_2017, title={On the structure of softwood kraft lignin}, volume={19}, ISSN={["1463-9270"]}, url={https://doi.org/10.1039/C7GC01812F}, DOI={10.1039/c7gc01812f}, abstractNote={Two constitutional structural schemes are proposed attempting to unify and rationalize a series of focused NMR and chromatographic determinations aimed at providing an integrated picture for the structure of softwood kraft lignin.}, number={17}, journal={GREEN CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Crestini, Claudia and Lange, Heiko and Sette, Marco and Argyropoulos, Dimitris S.}, year={2017}, month={Sep}, pages={4104–4121} }
 @misc{patil_argyropoulos_2017, title={Stable Organic Radicals in Lignin: A Review}, volume={10}, ISSN={["1864-564X"]}, DOI={10.1002/cssc.201700869}, abstractNote={Lignin and the quest for the origin of stable organic radicals in it have seen numerous developments. Although there have been various speculations over the years on the formation of these stable radicals, researchers have not been able to arrive at a solid, unequivocal hypothesis that applies to all treatments and types of lignin. The extreme complexity of lignin and its highly aromatic, cross-linked, branched, and rigid structure has made such efforts rather cumbersome. Since the early 1950s, researchers in this field have dedicated their efforts to the establishment of methods for the detection and determination of spin content, theoretical simulations, and reactions on model compounds and spin-trapping studies. Although a significant amount of published research is available on lignin or its model compounds and the reactive intermediates involved during various chemical treatments (pulping, bleaching, extractions, chemical modifications, etc.), the literature provides a limited view on the origin, nature, and stability of such radicals. Consequently, this review is focused on examining the origin of such species in lignin, factors affecting their presence, reactions involved in their formation, and methods for their detection.}, number={17}, journal={CHEMSUSCHEM}, author={Patil, Shradha V. and Argyropoulos, Dimitris S.}, year={2017}, month={Sep}, pages={3284–3303} }
 @article{pang_yang_fang_yuan_argyropoulos_sun_2017, title={Structure-property relationships for technical lignins for the production of lignin-phenol-formaldehyde resins}, volume={108}, ISSN={["1872-633X"]}, DOI={10.1016/j.indcrop.2017.07.009}, abstractNote={The synthesis and performance of a lignin-phenol-formaldehyde resin are significantly related to the properties of the lignin used. In an effort to provide a fundamental understanding of lignin structure-property relations for lignin-phenol-formaldehyde resin synthesis and application, two distinct technical lignins were examined as-obtained from an acidic (L1) and an alkaline (L2) organosolv pulping of bamboo. These samples were thoroughly characterized and the structural and compositional features of them were charted. The content of β-O-4′ linkages in L1 were 23.83 per 100Ar, followed by some β-β′ linkages (1.27 per 100Ar). However, almost all the side-chain linkages in L2 were cleaved. The purities of the two lignins both exceeded 81.0%, but significantly more extractives were found to be present in L2. Subsequently, two lignin-phenol-formaldehyde resins were successfully synthesized using L1 and purified L2 at a substitution rate of 50% to phenol. The high content of extractives contaminating L2, especially long-chain hydrocarbon derivatives, severely affected the synthesis of lignin-phenol-formaldehyde resin. The successful removal of this fraction was necessary before the material could be put to use.}, journal={INDUSTRIAL CROPS AND PRODUCTS}, author={Pang, Bo and Yang, Sheng and Fang, Wei and Yuan, Tong-Qi and Argyropoulos, Dimitris S. and Sun, Run-Cang}, year={2017}, month={Dec}, pages={316–326} }
 @article{argyropoulos_crestini_2016, title={A Perspective on Lignin Refining, Functionalization, and Utilization}, volume={4}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.6b02173}, abstractNote={ADVERTISEMENT RETURN TO ISSUEEditorialNEXTGet e-AlertsA Perspective on Lignin Refining, Functionalization, and UtilizationDimitris S. Argyropoulos and Claudia CrestiniView Author Information North Carolina State University, United States Tor Vergata University, ItalyCite this: ACS Sustainable Chem. Eng. 2016, 4, 10, 5089Publication Date (Web):October 3, 2016Publication History Received9 September 2016Published online3 October 2016Published inissue 3 October 2016https://doi.org/10.1021/acssuschemeng.6b02173Copyright © 2016 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views1684Altmetric1Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (150 KB) Get e-AlertsSUBJECTS:Biopolymers,Organic polymersGet e-Alerts ACS Sustainable Chemistry & Engineering Get e-Alerts}, number={10}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Argyropoulos, Dimitris S. and Crestini, Claudia}, year={2016}, month={Oct}, pages={5089–5089} }
 @article{koivu_sadeghifar_nousiainen_argyropoulos_sipila_2016, title={Effect of Fatty Acid Esterification on the Thermal Properties of Softwood Kraft Lignin}, volume={4}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.6b01048}, abstractNote={Esterification of kraft lignin inherently addresses its potential for thermoplastic applications either on its own or as a component of polymer blends. In this effort, we have investigated the selectivity of softwood kraft lignin toward esterification via acylation. LignoBoost kraft lignin was esterified with acetyl (C2), octanoyl (C8), lauroyl (C12), and palmitoyl (C16) chlorides at various molar ratios with respect to the total hydroxyls present. Quantitative 31P NMR spectroscopy, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC) were used to evaluate the selectivity and efficiency of these reactions on the various hydroxyl groups present. The C8–C16 acyl chlorides showed distinct enhanced reactivity toward the aliphatic hydroxyl groups, whereas C2 acyl chloride was found to react uniformly with any available OH irrespective of their chemical nature. The effects of long chain acylation on the polymer and material properties were also examined using solution viscosit...}, number={10}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Koivu, Klaus A. Y. and Sadeghifar, Hasan and Nousiainen, Paula A. and Argyropoulos, Dimitris S. and Sipila, Jussi}, year={2016}, month={Oct}, pages={5238–5247} }
 @article{sen_losey_gordon_argyropoulos_martin_2016, title={Ionic Liquid Character of Zinc Chloride Hydrates Define Solvent Characteristics that Afford the Solubility of Cellulose}, volume={120}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/acs.jpcb.5b11400}, DOI={10.1021/acs.jpcb.5b11400}, abstractNote={The recently described ionic liquid structure of the three equivalent hydrate of zinc chloride (ZnCl2·R H2O, R = 3, existing as [Zn(OH2)6][ZnCl4]) explains the solubility of cellulose in this medium. Only hydrate compositions in the narrow range of 3 - x < R < 3 + x with x ≈ 1 dissolve cellulose. Once dissolved, the cellulose remains in solution up to the R = 9 hydrate. Neutron diffraction and differential pair distribution function analysis of cellulose and model compound solutions (1 wt % cellulose in the R = 3 hydrate and 1 wt % ethanol in the R = 3 hydrate and the ZnCl2·3 ethanol liquid) coupled with detailed solubility measurements suggest that cellulose solubility occurs via coordination of the primary OH to the hydrated zinc cation with ring hydroxyls forming part of a second coordination shell around the cation of the ionic liquid.}, number={6}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Sen, Sanghamitra and Losey, Bradley P. and Gordon, Elijah E. and Argyropoulos, Dimitris S. and Martin, James D.}, year={2016}, month={Feb}, pages={1134–1141} }
 @article{sadeghifar_argyropoulos_2016, title={Macroscopic Behavior of Kraft Lignin Fractions: Melt Stability Considerations for Lignin-Polyethylene Blends}, volume={4}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.6b00636}, abstractNote={Questions that pertain to the behavior of softwood kraft lignin fractions as opposed to the whole lignin still prevail. In an effort to further understand such effects at a macroscopic level, we have examined the issue of melt stability of polyethylene (PE) in blends with fractionated and unfractionated softwood kraft lignin. While methylation of the phenolic OH groups significantly stabilizes any lignin/PE melt, more in depth data demonstrate that when separate, acetone soluble (ASKL) and acetone insoluble (AIKL) kraft lignin fractions behave completely differently than the original unfractionated material. The low molecular weight methylated ASKL offers unexpected plasticizing action to PE melts, possibly as a consequence of its low molecular weight and spherical configuration. The higher molecular weight AIKL offers relatively stable PE melts, possibly manifesting its rigid nature and higher glass transition temperature likely occurring due to π stacking operating among its aromatic rings. Mixing these...}, number={10}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Sadeghifar, Hasan and Argyropoulos, Dimitris S.}, year={2016}, month={Oct}, pages={5160–5166} }
 @article{sadeghifar_sen_patil_argyropoulos_2016, title={Toward Carbon Fibers from Single Component Kraft Lignin Systems: Optimization of Chain Extension Chemistry}, volume={4}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.6b00848}, abstractNote={Single component softwood kraft lignins have been sought after as precursors to carbon fibers. This noble goal can be achieved by adding carbon onto lignin via propargylation. The reactivity of propargylated lignins may then be modulated via methylation, thus eliminating the onset of gelation via phenoxyl radical initiated random polymerization. This article demonstrates that properly installed propargyl groups of an acetone soluble kraft lignin (ASKL) fraction can be thermally polymerized to high molecular weights in a controlled manner. In order to create single component chain extended softwood kraft lignin systems for carbon fiber applications, one needs to regulate the amount and the positioning of the propargyl groups on the lignin. This became possible, and it is now demonstrated that the propargylation of lignin needs to occur first, followed by methylation and not the other way around. Such a sequence offers substantial benefits for the onset of a Claisen rearrangement to occur between the propargyl groups and the free C5 positions of the softwood lignin. Furthermore, once in position, the created benzopyrans can effectively further polymerize in a controlled manner offering chain extended kraft lignin products of sufficient molecular weight so as to apply subsequent stabilization and carbonization steps to it.}, number={10}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Sadeghifar, Hasan and Sen, Sanghamitra and Patil, Shradha V. and Argyropoulos, Dimitris S.}, year={2016}, month={Oct}, pages={5230–5237} }
 @article{sadeghifar_argyropoulos_2015, title={Correlations of the Antioxidant Properties of Softwood Kraft Lignin Fractions with the Thermal Stability of Its Blends with Polyethylene}, volume={3}, ISSN={["2168-0485"]}, DOI={10.1021/sc500756n}, abstractNote={Since technical lignins are increasingly considered as additives to polyolefins, an effort is made here to understand the fundamental antioxidant properties of softwood kraft lignin and its fractions on the thermal stability of its blends with polyethylene. Lower molecular weight acetone soluble kraft lignin (ASKL) fractions showed better antioxidant properties than unfractionated and acetone insoluble kraft lignin (AIKL). By selectively methylating the phenolic hydroxyl groups of the lignin and its fractions, it was shown that the lignin had no antioxidant ability. The phenolic OH groups in lignin, therefore, play a vital role toward imparting antioxidant characteristics in it. To further understand the role of lignin during the thermal processing of polyethylene, we measured the oxidation induction temperature (OITtemp) of its blends with softwood kraft lignin and its fractions. Once again, the role of the phenolic OH was found to be extremely important toward the thermal oxidative characteristics of kraft lignin and its fractions. Since acetone soluble softwood kraft lignin contains 54% more phenolic units than its acetone insoluble counterpart, its blends (5 wt %) with polyethylene improved its OITtemp by about 50 °C with no additional increases at higher lignin contents. At elevated processing temperatures, when polyethylene blends of lignin start to degrade, the aromatic nature of the created char reduces its rate of degradation, concomitantly increasing the thermal degradation temperature of polyethylene. This effect was further investigated and details of the relative contributions of the phenolic OH stabilization mechanism to the charring mechanism are discussed.}, number={2}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Sadeghifar, Hasan and Argyropoulos, Dimitris S.}, year={2015}, month={Feb}, pages={349–356} }
 @article{leskinen_kelley_argyropoulos_2015, title={Determination of molecular weight distributions in native and pretreated wood}, volume={119}, ISSN={0144-8617}, url={http://dx.doi.org/10.1016/J.CARBPOL.2014.11.026}, DOI={10.1016/J.CARBPOL.2014.11.026}, abstractNote={The analysis of native wood components by size-exclusion chromatography (SEC) is challenging. Isolation, derivatization and solubilization of wood polymers is required prior to the analysis. The present approach allowed the determination of molecular weight distributions of the carbohydrates and of lignin in native and processed woods, without preparative component isolation steps. For the first time a component selective SEC analysis of sawdust preparations was made possible by the combination of two selective derivatization methods, namely; ionic liquid assisted benzoylation of the carbohydrate fraction and acetobromination of the lignin in acetic acid media. These were optimized for wood samples. The developed method was thus used to examine changes in softwood samples after degradative mechanical and/or chemical treatments, such as ball milling, steam explosion, green liquor pulping, and chemical oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The methodology can also be applied to examine changes in molecular weight and lignin-carbohydrate linkages that occur during wood-based biorefinery operations, such as pretreatments, and enzymatic saccharification.}, journal={Carbohydrate Polymers}, publisher={Elsevier BV}, author={Leskinen, Timo and Kelley, Stephen S. and Argyropoulos, Dimitris S.}, year={2015}, month={Mar}, pages={44–52} }
 @article{sen_patil_argyropoulos_2015, title={Methylation of softwood kraft lignin with dimethyl carbonate}, volume={17}, ISSN={["1463-9270"]}, DOI={10.1039/c4gc01759e}, abstractNote={Methylation of lignin is essential for inducing thermal stability when a multitude of thermoplastic applications are envisaged.}, number={2}, journal={GREEN CHEMISTRY}, author={Sen, Sanghamitra and Patil, Shradha and Argyropoulos, Dimitris S.}, year={2015}, pages={1077–1087} }
 @article{hu_heitmann_zhong_lucia_argyropoulos_2015, title={Quantitative Study of the Interfacial Adsorption of Cellullase to Cellulose}, volume={119}, ISSN={["1932-7455"]}, DOI={10.1021/acs.jpcc.5b02011}, abstractNote={The phenomenon of interfacial adsorption of cellulase to cellulose plays a significant role in its enzymatic conversion to a variety of biomaterials and biofuels. The crystallinity and surface areas are the key substrate characteristics that must be considered in its final conversion to soluble sugars. This research therefore characterized the crystallinity and surface areas of microcrystalline celluloses and hardwood pulps as a function of the interfacial activity of cellulase, and thereafter the effects of these two parameters on adsorption were modeled. The crystallinities were characterized by X-ray diffraction, while surface areas by laser scattering and Congo red adsorption. It was found that cellulase adsorption to cellulose follows a Langmuir model while statistical modeling showed that surface area, crystallinity, and their interactions were determined to be significant for cellulase adsorption over a temperature range of 4–50 °C.}, number={25}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Hu, Gang and Heitmann, John A. and Zhong, Biao and Lucia, Lucian A. and Argyropoulos, Dimitris S.}, year={2015}, month={Jun}, pages={14160–14166} }
 @article{leskinen_kelley_argyropoulos_2015, title={Refining of Ethanol Biorefinery Residues to Isolate Value Added Lignins}, volume={3}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.5b00337}, abstractNote={The isolation of lignin coproducts from the residual solids of a hardwood based biocatalytic bioethanol process was examined, using extraction methods based on aqueous alkali or aqueous ethanol. This work focused on understanding how the structural features of raw lignin in the process residue influenced the refined lignin isolation yields, in addition to polymeric and structural characteristics. On the basis of this approach, the extraction based lignin refining could be optimized. Mild extraction conditions allowed for recovery of approximately 40 wt % of the lignin present in the starting material. This yield could be increased to about 76 wt %, by the application of base or acid catalyzed reactive extraction conditions liberating the bonded insoluble fractions of the residue. All isolated lignin products were characterized in terms of their functional groups, molecular weights and thermal properties. The lignins from mild alkali and ethanol extractions showed similarities in their chemical profiles. I...}, number={7}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Leskinen, Timo and Kelley, Stephen S. and Argyropoulos, Dimitris S.}, year={2015}, month={Jul}, pages={1632–1641} }
 @article{carpenter_scholle_sadeghifar_francis_boltersdorf_weare_argyropoulos_maggard_ghiladi_2015, title={Synthesis, Characterization, and Antimicrobial Efficacy of Photomicrobicidal Cellulose Paper}, volume={16}, ISSN={["1526-4602"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84938937944&partnerID=MN8TOARS}, DOI={10.1021/acs.biomac.5b00758}, abstractNote={Toward our goal of scalable, antimicrobial materials based on photodynamic inactivation, paper sheets comprised of photosensitizer-conjugated cellulose fibers were prepared using porphyrin and BODIPY photosensitizers, and characterized by spectroscopic (infrared, UV–vis diffuse reflectance, inductively coupled plasma optical emission) and physical (gel permeation chromatography, elemental, and thermal gravimetric analyses) methods. Antibacterial efficacy was evaluated against Staphylococcus aureus (ATCC-2913), vancomycin-resistant Enterococcus faecium (ATCC-2320), Acinetobacter baumannii (ATCC-19606), Pseudomonas aeruginosa (ATCC-9027), and Klebsiella pneumoniae (ATCC-2146). Our best results were achieved with a cationic porphyrin–paper conjugate, Por(+)-paper, with inactivation upon illumination (30 min, 65 ± 5 mW/cm2, 400–700 nm) of all bacterial strains studied by 99.99+% (4 log units), regardless of taxonomic classification. Por(+)-paper also inactivated dengue-1 virus (>99.995%), influenza A (∼99.5%), and human adenovirus-5 (∼99%). These results demonstrate the potential of cellulose materials to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.}, number={8}, journal={BIOMACROMOLECULES}, author={Carpenter, Bradley L. and Scholle, Frank and Sadeghifar, Hasan and Francis, Aaron J. and Boltersdorf, Jonathan and Weare, Walter W. and Argyropoulos, Dimitris S. and Maggard, Paul A. and Ghiladi, Reza A.}, year={2015}, month={Aug}, pages={2482–2492} }
 @misc{sen_patil_argyropoulos_2015, title={Thermal properties of lignin in copolymers, blends, and composites: a review}, volume={17}, ISSN={["1463-9270"]}, DOI={10.1039/c5gc01066g}, abstractNote={Modulating thermal properties<italic>via</italic>lignin copolymers, blends, and composites.}, number={11}, journal={GREEN CHEMISTRY}, author={Sen, Sanghamitra and Patil, Shradha and Argyropoulos, Dimitris S.}, year={2015}, pages={4862–4887} }
 @article{leskinen_salas_kelley_argyropoulos_2015, title={Wood Extractives Promote Cellulase Activity on Cellulosic Substrates}, volume={16}, ISSN={1525-7797 1526-4602}, url={http://dx.doi.org/10.1021/ACS.BIOMAC.5B00889}, DOI={10.1021/acs.biomac.5b00889}, abstractNote={Deposition of hydrophobic wood extractives and representative model compounds, on the surface of cellulose prior to enzymatic hydrolysis was found to either enhance or inhibit the action of cellulase enzymes. The effect of these compounds was correlated with their chemical structure, which may in part explain the differential effects observed between softwood and hardwood extractives. Specifically, the addition of sterol, enhanced enzymatic hydrolysis of microcrystalline cellulose by 54%, whereas the addition of a triglyceride could inhibit the hydrolysis by 49%. The effects of the different extractives’ could be explained by considering their Hansen solubility parameters. The amphiphilic and/or hydrophobic character of model extractives was found to be the variable that affected the deposition of extractives on cellulose surfaces and the eventual adsorption of cellulolytic enzymes on it. The observed beneficial effects of extractives are likely related to a reduction in the irreversible binding of the enzymes on the cellulose surface.}, number={10}, journal={Biomacromolecules}, publisher={American Chemical Society (ACS)}, author={Leskinen, Timo and Salas, Carlos and Kelley, Stephen S. and Argyropoulos, Dimitris S.}, year={2015}, month={Sep}, pages={3226–3234} }
 @article{gao_li_xiang_chen_yang_argyropoulos_2014, title={Efficient One-Pot Synthesis of 5-Chloromethyl-furfural (CMF) from Carbohydrates in Mild Biphasic Systems. (vol 18, pg 7675, 2013)}, volume={19}, ISSN={["1420-3049"]}, DOI={10.3390/molecules19011370}, abstractNote={We have recently been made aware by Prof. Mark Mascal (University of California Davis) and the Molecules Editorial Offices of some errors and omissions in the Introduction section of our recent paper. [...]}, number={1}, journal={MOLECULES}, author={Gao, Wenhua and Li, Yiqun and Xiang, Zhouyang and Chen, Kefu and Yang, Rendang and Argyropoulos, Dimitris S.}, year={2014}, month={Jan}, pages={1370–1374} }
 @article{cui_sun_argyropoulos_2014, title={Fractional Precipitation of Softwood Kraft Lignin: Isolation of Narrow Fractions Common to a Variety of Lignins}, volume={2}, ISSN={["2168-0485"]}, DOI={10.1021/sc400545d}, abstractNote={In a manner similar to crude oil, technical lignins need refining if their potential as reactive polyphenols of well-defined molecular weight polymers and oligomers is to be actualized. In this paper, we demonstrate that a continuum of narrow fractions can be isolated by the incremental addition of a nonpolar solvent (hexanes) in a polar (acetone) solution of softwood wood kraft lignin. Three distinct commercial samples of softwood kraft lignin were used to examine the validity of the developed protocol using detailed chromatographic and quantitative functional group analytical methods. It was shown that all samples contain a common relatively monodisperse fraction of a polyphenolic material that can be isolated from the different lignins in yields ranging between 10 and 20% w/w. The versatility of the developed fractional precipitation protocol was further validated by creating artificial physical mixtures of the examined lignins in different proportions and isolating from them precisely calculated fractions of nearly identical molecular weight distributions and composition. Overall, the fractional precipitation approach described here offers the possibility that representative specific narrow fractions, common to a variety of softwood kraft lignins, can be isolated irrespective of the manufacturing details of the pulping process. As such, the otherwise known heterogeneous kraft lignin material, whose composition is relatively unpredictable due to manufacturing variations in making pulp, may now offer consistently homogeneous lignin streams with significant commercial ramifications.}, number={4}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Cui, Chengzhong and Sun, Runkun and Argyropoulos, Dimitris S.}, year={2014}, month={Apr}, pages={959–968} }
 @article{sadeghifar_dickerson_argyropoulos_2014, title={Quantitative P-31 NMR analysis of solid wood offers an insight into the acetylation of its components}, volume={113}, ISSN={["1879-1344"]}, DOI={10.1016/j.carbpol.2014.07.046}, abstractNote={As a solid substrate, wood and its components are almost invariably examined via spectroscopic or indirect methods of analysis. Unlike earlier approaches, in this effort we dissolve pulverized wood in ionic liquid and then directly derive its functional group contents by quantitative 31P NMR. As such, this novel analytical methodology is thoroughly examined and an insight into the detailed way acetylation proceeds on solid wood and its components is provided as a function of wood density and within its various anatomical features. As anticipated, the efficiency of acetylation was found to be greater within low density wood than in high density wood. The lignin, the cellulose and the hemicelluloses of the low density wood was found to be acetylated nearly twice as fast with remarkable differences in their quantitative degree of acetylation amongst them. This direct analytical data validates the applied methodology and confirms, for the first time, that the order of acetylation in solid wood is lignin > hemicellulose > cellulose and no reactivity differences exist between early wood and late wood.}, journal={CARBOHYDRATE POLYMERS}, author={Sadeghifar, Hasan and Dickerson, James P. and Argyropoulos, Dimitris S.}, year={2014}, month={Nov}, pages={552–560} }
 @article{argyropoulos_sadeghifar_cui_sen_2014, title={Synthesis and Characterization of Poly(arylene ether sulfone) Kraft Lignin Heat Stable Copolymers}, volume={2}, ISSN={["2168-0485"]}, DOI={10.1021/sc4002998}, abstractNote={In this effort we aim at documenting our understanding of using the phenolic hydroxyl groups of technical softwood kraft lignin in replacing the multifunctional phenolic component required for the synthesis of poly(arylene ether) sulfones. To do this we use a two-pronged approach that uses fractionated softwood kraft lignin whose phenolic hydroxyl groups have been systematically protected in order to avoid gelation when copolymerized with 4, 4′-diflourodiphenyl sulfone (DFDPS). This has been done by careful 31P NMR profiling of the various hydroxyl groups present in the lignin as a function of the degree of phenolic hydroxyl group protection. For all copolymers, weight average molecular weights (Mw), polydispersity indices (PDI), glass transition temperatures (Tg), and thermal stability profiles (TGA) were obtained, providing an integrated picture of the scientific and technological ramifications of this work. Overall, this effort provides the foundations for creating lignin copolymers of controlled and modulated characteristics exhibiting augmented thermal stability. Such thermal properties and uniform molecular weight distributions of lignins and copolymers produced from commercial lignins provides a means for beneficially modulating the properties of an otherwise intractable biopolymer.}, number={2}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Argyropoulos, Dimitris S. and Sadeghifar, Hasan and Cui, Chengzhong and Sen, Sanghamitra}, year={2014}, month={Feb}, pages={264–271} }
 @article{gao_li_xiang_chen_yang_argyropoulos_2013, title={Efficient One-Pot Synthesis of 5-Chloromethylfurfural (CMF) from Carbohydrates in Mild Biphasic Systems}, volume={18}, ISSN={["1420-3049"]}, DOI={10.3390/molecules18077675}, abstractNote={5-Halomethylfurfurals can be considered as platform chemicals of high reactivity making them useful for the preparation of a variety of important compounds. In this study, a one-pot route for the conversion of carbohydrates into 5-chloromethylfurfural (CMF) in a simple and efficient (HCl-H3PO4/CHCl3) biphasic system has been investigated. Monosaccharides such as D-fructose, D-glucose and sorbose, disaccharides such as sucrose and cellobiose and polysaccharides such as cellulose were successfully converted into CMF in satisfactory yields under mild conditions. Our data shows that when using D-fructose the optimum yield of CMF was about 47%. This understanding allowed us to extent our work to biomaterials, such as wood powder and wood pulps with yields of CMF obtained being comparable to those seen with some of the enumerated mono and disaccharides. Overall, the proposed (HCl-H3PO4/CHCl3) optimized biphasic system provides a simple, mild, and cost-effective means to prepare CMF from renewable resources.}, number={7}, journal={MOLECULES}, author={Gao, Wenhua and Li, Yiqun and Xiang, Zhouyang and Chen, Kefu and Yang, Rendang and Argyropoulos, Dimitris S.}, year={2013}, month={Jul}, pages={7675–7685} }
 @article{leskinen_king_kilpeläinen_argyropoulos_2013, title={Fractionation of Lignocellulosic Materials Using Ionic Liquids: Part 2. Effect of Particle Size on the Mechanisms of Fractionation}, volume={52}, ISSN={0888-5885 1520-5045}, url={http://dx.doi.org/10.1021/IE302896N}, DOI={10.1021/IE302896N}, abstractNote={In part 1 of this effort (Ind. Eng. Chem. Res. 2011, 50, 12349−12357), we studied how wood dissolved in ionic liquid (IL) is precipitated into different molecular weight ranges upon the addition of a cosolvent. In this article, we further analyze the chemical compositions of these fractions and elucidate the mechanisms of fractionation. Specifically, we fractionated Norway spruce wood solvated with 1-allyl-3-methylimidazolium chloride ([amim]Cl) and analyzed the resulting fractions by Klason lignin analysis and FT-IR and NMR spectroscopies. We found that separation of the different components can be tuned by the variable dissolution of wood based on particle size, resulting from preparatory milling. It is possible to obtain cellulose-rich material with a relatively low (6.2%) lignin content, from spruce sawdust. This can achieved by extracting the cellulose from the insoluble lignin–carbohydrate complex (LCC) matrix. Extensive milling of wood afforded a soluble LCC matrix, and its precipitation was based on molecular weight and not on chemical composition. Indications of the presence of LCCs in the hemicellulose fraction were obtained by utilizing multidimensional NMR spectroscopy.}, number={11}, journal={Industrial & Engineering Chemistry Research}, publisher={American Chemical Society (ACS)}, author={Leskinen, Timo and King, Alistair W. T. and Kilpeläinen, Ilkka and Argyropoulos, Dimitris S.}, year={2013}, month={Mar}, pages={3958–3966} }
 @article{sen_sadeghifar_argyropoulost_2013, title={Kraft Lignin Chain Extension Chemistry via Propargylation, Oxidative Coupling, and Claisen Rearrangement}, volume={14}, ISSN={["1526-4602"]}, DOI={10.1021/bm4010172}, abstractNote={Despite its aromatic and polymeric nature, the heterogeneous, stochastic, and reactive characteristics of softwood kraft lignin seriously limit its potential for thermoplastic applications. Our continuing efforts toward creating thermoplastic lignin polymers are now focused at exploring propargylation derivatization chemistry and its potential as a versatile novel route for the eventual utilization of technical lignins with a significant amount of molecular control. To do this, we initially report the systematic propargylation of softwood kraft lignin. The synthesized derivatives were extensively characterized with thermal methods (DSC, TGA), 1H, 13C, and quantitative 31P NMR and IR spectroscopies. Further on, we explore the versatile nature of the lignin pendant propargyl groups by demonstrating two distinct chain extension chemistries; the solution-based, copper-mediated, oxidative coupling and the thermally induced, solid-state, Claissen rearrangement polymerization chemistries. Overall, we show that it is possible to modulate the reactivity of softwood kraft lignin via a combination of methylation and chain extension providing a rational means for the creation of higher molecular weight polymers with the potential for thermoplastic materials and carbon fibers with the desired control of structure–property relations.}, number={10}, journal={BIOMACROMOLECULES}, author={Sen, Sanghamitra and Sadeghifar, Hasan and Argyropoulost, Dimitris S.}, year={2013}, month={Oct}, pages={3399–3408} }
 @article{sen_martin_argyropoulos_2013, title={Review of Cellulose Non-Derivatizing Solvent Interactions with Emphasis on Activity in Inorganic Molten Salt Hydrates}, volume={1}, ISSN={2168-0485 2168-0485}, url={http://dx.doi.org/10.1021/SC400085A}, DOI={10.1021/SC400085A}, abstractNote={During cellulose dissolution in non-derivatizing solvents, the inter- and intramolecular hydrogen bonds of the polymer are deconstructed. This occurs either by hydrogen bond formation between one or more components of the solvent systems and the hydroxyl groups of the cellulose or by coordination bond formation between the metal ion present in the medium and the hydroxyl group of cellulose molecules. None of the polymer molecules are actually chemically modified during dissolution. In the first part of this review, we examine the literature pertaining to the different interaction mechanisms between cellulose and non-derivatizing solvent systems with emphasis on the inorganic molten salt hydrates. In the second part of this effort, we further review inorganic molten salt hydrates from the point of view of the changes they impart to the physical properties of the cellulose and the various chemical reactions that can be performed in it.}, number={8}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Sen, Sanghamitra and Martin, James D. and Argyropoulos, Dimitris S.}, year={2013}, month={Jun}, pages={858–870} }
 @article{asikkala_tamminen_argyropoulos_2012, title={Accurate and Reproducible Determination of Lignin Molar Mass by Acetobromination}, volume={60}, ISSN={["1520-5118"]}, DOI={10.1021/jf303003d}, abstractNote={The accurate and reproducible determination of lignin molar mass by using size exclusion chromatography (SEC) is challenging. The lignin association effects, known to dominate underivatized lignins, have been thoroughly addressed by reaction with acetyl bromide in an excess of glacial acetic acid. The combination of a concerted acetylation with the introduction of bromine within the lignin alkyl side chains is thought to be responsible for the observed excellent solubilization characteristics acetobromination imparts to a variety of lignin samples. The proposed methodology was compared and contrasted to traditional lignin derivatization methods. In addition, side reactions that could possibly be induced under the acetobromination conditions were explored with native softwood (milled wood lignin, MWL) and technical (kraft) lignin. These efforts lend support toward the use of room temperature acetobromination being a facile, effective, and universal lignin derivatization medium proposed to be employed prior to SEC measurements.}, number={36}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Asikkala, Janne and Tamminen, Tarja and Argyropoulos, Dimitris S.}, year={2012}, month={Sep}, pages={8968–8973} }
 @article{carpenter_feese_sadeghifar_argyropoulos_ghiladi_2012, title={Porphyrin-Cellulose Nanocrystals: A Photobactericidal Material that Exhibits Broad Spectrum Antimicrobial Activity†}, volume={88}, ISSN={0031-8655}, url={http://dx.doi.org/10.1111/j.1751-1097.2012.01117.x}, DOI={10.1111/j.1751-1097.2012.01117.x}, abstractNote={Towards our overall objectives of developing potent antimicrobial materials to combat the escalating threat to human health posed by the transmission of surface-adhering pathogenic bacteria, we have investigated the photobactericidal activity of cellulose nanocrystals that have been modified with a porphyrin-derived photosensitizer (PS). The ability of these previously synthesized porphyrin-cellulose-nanocrystals (CNC-Por (1)) to mediate bacterial photodynamic inactivation was investigated as a function of bacterial strain, incubation time and illumination time. Despite forming an insoluble suspension, CNC-Por (1) showed excellent efficacy toward the photodynamic inactivation of Acinetobacter baumannii, multidrug-resistant Acinetobacter baumannii (MDRAB) and methicillin-resistant Staphylococcus aureus (MRSA), with the best results achieving 5–6 log units reduction in colony forming units (CFUs) upon illumination with visible light (400–700 nm; 118 J cm−2). CNC-Por (1) mediated the inactivation of Pseudomonas aeruginosa, although at reduced activity (2–3 log units reduction). Confocal laser scanning microscopy of CNC-Por (1) after incubation with A. baumannii or S. aureus suggested a lack of internalization of the PS. Research into alternative materials such as CNC-Por (1) may lead to their application in hospitals and healthcare-related industries wherein novel materials with the capability of reducing the rates of transmission of a wide range of bacteria, particularly antibiotic resistant strains, are desired.}, number={3}, journal={Photochemistry and Photobiology}, publisher={Wiley}, author={Carpenter, Bradley L. and Feese, Elke and Sadeghifar, Hasan and Argyropoulos, Dimitris S. and Ghiladi, Reza A.}, year={2012}, month={Mar}, pages={527–536} }
 @article{sadeghifar_cui_argyropoulos_2012, title={Toward Thermoplastic Lignin Polymers. Part 1. Selective Masking of Phenolic Hydroxyl Groups in Kraft Lignins via Methylation and Oxypropylation Chemistries}, volume={51}, ISSN={["0888-5885"]}, DOI={10.1021/ie301848j}, abstractNote={This work offers a comprehensive understanding of the conditions required for the selective masking of the phenolic hydroxyl groups in technical kraft lignins, which is pivotal in determining their subsequent chemical and thermal reactivity. To this effect, we have examined the chemistry and developed the conditions for the facile, mild, and selective masking of the phenolic hydroxyl groups in softwood and hardwood kraft lignins. We have compared two series of methylated softwood kraft lignins synthesized using different methylation chemistries. Our data show that (when used as specified) dimethyl sulfate in aqueous NaOH selectively converts the phenolic hydroxyl groups of kraft lignin to its methylated derivatives without apparent side reactions. In contrast, methyl iodide (in the presence of excess K2CO3 in N,N-dimethylformamide) was found to be rather ineffective and unselective. Various milder methylation conditions were also examined for both softwood and hardwood kraft lignins using dimethyl sulfate, and the details of this work are documented. In addition, a series of oxypropylation reactions were also carried out using propylene oxide in aqueous NaOH. Propylene oxide was shown to selectively add (at room temperature, 0.5 M NaOH, 18 h) less than two units on average per phenolic hydroxyl group without significant additional polymerization or other side reactions.}, number={51}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Sadeghifar, Hasan and Cui, Chengzhong and Argyropoulos, Dimitris S.}, year={2012}, month={Dec}, pages={16713–16720} }
 @article{leskinen_king_kilpelainen_argyropoulos_2011, title={Fractionation of Lignocellulosic Materials with Ionic Liquids. 1. Effect of Mechanical Treatment}, volume={50}, ISSN={["0888-5885"]}, DOI={10.1021/ie200063x}, abstractNote={The selective precipitation of wood dissolved in 1-allyl-3-methylimidazolium chloride ([amim]Cl) with a nonsolvent is a straightforward method for fractionating lignocellulosic components. In this study we have solvated and precipitated fractions of pulverized Norway spruce (Picea abies) and Eucalyptus grandis wood. This was achieved by agitating and heating the lignocellulosic materials in [amim]Cl followed by precipitation using nonsolvents, such as acetonitrile (MeCN) and water. Water was also used to extract material, which was determined to be high molecular weight galactoglucomannan. Products were analyzed by benzoylation followed by size-exclusion chromatography (SEC) and IR. It was found that the selectivity of precipitation was not significantly dependent upon the chemical composition of the precipitating components. The efficiency of precipitation was found to be dependent upon molecular weight, with the dissolved higher molecular weight and partially soluble wood components precipitating first. Moreover, when coarse sawdust samples were fractionated, the selective dissolution of cellulose from the fiber was observed, which allowed for the regeneration of a fraction of delignified and bleachable cellulose. Additionally, finely milled softwood samples, with demonstrated narrowly distributed low molecular weights, did not efficiently fractionate most likely due to the presence of an extensive lignin–carbohydrate complex (LCC) network.}, number={22}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Leskinen, Timo and King, Alistair W. T. and Kilpelainen, Ilkka and Argyropoulos, Dimitris S.}, year={2011}, month={Nov}, pages={12349–12357} }
 @article{zoia_king_argyropoulos_2011, title={Molecular Weight Distributions and Linkages in Lignocellulosic Materials Derivatized from Ionic Liquid Media}, volume={59}, ISSN={0021-8561 1520-5118}, url={http://dx.doi.org/10.1021/jf103615e}, DOI={10.1021/jf103615e}, abstractNote={A novel and reproducible method is described for accurately determining the molecular weight distribution by size exclusion chromatography (SEC) of whole lignocellulosic materials. This approach offers the opportunity to compare the molecular weight distributions of intact milled woods and its component fractions, lignins and holocelluloses, all from the same source, thus highlighting the potential of the technique and the contributions of the individual components to the chromatogram. The method is based on the dissolution of the ball-milled samples in the ionic liquid 1-allyl-3-methylimidazolium chloride ([amim]Cl). Under these homogeneous ionic liquid media, a derivatization reaction was performed with benzoyl chloride in the presence of pyridine. The thoroughly benzoylated wood with its associated carbohydrate and lignin components was found to be completely soluble in the THF SEC eluent with marked UV detector sensitivity. This methodology, when applied to the individually isolated holocellulose and lignin (enzymatic mild acidolysis lignin; EMAL) materials from Norway spruce ( Eucalyptus grandis ) wood and corn stover, offered a better understanding as to the possible ways the lignin and the carbohydrates may interact within these three different species. Finally, the applicability of the methodology is shown for a series of pure cellulosic samples under intense mechanical defibration conditions, offering a visualization of the molecular weight distribution changes induced during the production of nanofibrillated cellulose.}, number={3}, journal={Journal of Agricultural and Food Chemistry}, publisher={American Chemical Society (ACS)}, author={Zoia, Luca and King, Alistair W. T. and Argyropoulos, Dimitris S.}, year={2011}, month={Feb}, pages={829–838} }
 @article{feese_sadeghifar_gracz_argyropoulos_ghiladi_2011, title={Photobactericidal Porphyrin-Cellulose Nanocrystals: Synthesis, Characterization, and Antimicrobial Properties}, volume={12}, ISSN={1525-7797 1526-4602}, url={http://dx.doi.org/10.1021/bm200718s}, DOI={10.1021/bm200718s}, abstractNote={Adherence and survival of pathogenic bacteria on surfaces leading to concomitant transmission to new hosts significantly contributes to the proliferation of pathogens, which in turn considerably increases the threat to human health, particularly by antibiotic-resistant bacteria. Consequently, more research into effective surface disinfection and alternative materials (fabrics, plastics, or coatings) with antimicrobial and other bioactive characteristics is desirable. This report describes the synthesis and characterization of cellulose nanocrystals that were surface-modified with a cationic porphyrin. The porphyrin was appended onto the cellulose surface via the Cu(I)-catalyzed Huisgen–Meldal–Sharpless 1,3-dipolar cycloaddition having occurred between azide groups on the cellulosic surface and porphyrinic alkynes. The resulting, generally insoluble, crystalline material, CNC-Por (5), was characterized by infrared and diffusion 1H NMR spectroscopies, gel permeation chromatography, and thermogravimetric analysis. Although only suspended, and not dissolved, in an aqueous system, CNC-Por (5) showed excellent efficacy toward the photodynamic inactivation of Mycobacterium smegmatis and Staphylococcus aureus, albeit only slight activity against Escherichia coli. The synthesis, properties, and activity of CNC-Por (5) described herein serve as a benchmark toward our overall objectives of developing novel, potent, bioactive, photobactericidal materials that are effective against a range of bacteria, with potential utilization in the health care and food preparation industries.}, number={10}, journal={Biomacromolecules}, publisher={American Chemical Society (ACS)}, author={Feese, Elke and Sadeghifar, Hasan and Gracz, Hanna S. and Argyropoulos, Dimitris S. and Ghiladi, Reza A.}, year={2011}, month={Oct}, pages={3528–3539} }
 @article{sadeghifar_filpponen_clarke_brougham_argyropoulos_2011, title={Production of cellulose nanocrystals using hydrobromic acid and click reactions on their surface}, volume={46}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-011-5696-0}, number={22}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Sadeghifar, Hasan and Filpponen, Ilari and Clarke, Sarah P. and Brougham, Dermot F. and Argyropoulos, Dimitris S.}, year={2011}, month={Nov}, pages={7344–7355} }
 @article{monogioudi_permi_filpponen_lienemann_li_argyropoulos_buchert_mattinen_2011, title={Protein Analysis by 31P NMR Spectroscopy in Ionic Liquid: Quantitative Determination of Enzymatically Created Cross-Links}, volume={59}, ISSN={0021-8561 1520-5118}, url={http://dx.doi.org/10.1021/jf102973d}, DOI={10.1021/jf102973d}, abstractNote={Cross-linking of β-casein by Trichoderma reesei tyrosinase (TrTyr) and Streptoverticillium mobaraense transglutaminase (Tgase) was analyzed by 31P nuclear magnetic resonance (NMR) spectroscopy in ionic liquid (IL). According to 31P NMR, 91% of the tyrosine side chains were cross-linked by TrTyr at high dosages. When Tgase was used, no changes were observed because a different cross-linking mechanism was operational. However, this verified the success of the phosphitylation of phenolics within the protein matrix in the IL. Atomic force microscopy (AFM) in solid state showed that disk-shaped nanoparticles were formed in the reactions with average diameters of 80 and 20 nm for TrTyr and Tgase, respectively. These data further advance the current understanding of the action of tyrosinases on proteins on molecular and chemical bond levels. Quantitative 31P NMR in IL was shown to be a simple and efficient method for the study of protein modification.}, number={4}, journal={Journal of Agricultural and Food Chemistry}, publisher={American Chemical Society (ACS)}, author={Monogioudi, Evanthia and Permi, Perttu and Filpponen, Ilari and Lienemann, Michael and Li, Bin and Argyropoulos, Dimitris and Buchert, Johanna and Mattinen, Maija-Liisa}, year={2011}, month={Feb}, pages={1352–1362} }
 @article{zoia_perazzini_crestini_argyropoulos_2011, title={Understanding the radical mechanism of lipoxygenases using 31P NMR spin trapping}, volume={19}, ISSN={0968-0896}, url={http://dx.doi.org/10.1016/j.bmc.2011.02.046}, DOI={10.1016/j.bmc.2011.02.046}, abstractNote={In this paper, we use our quantitative (31)P NMR spin trapping methods, already developed for simple oxygen- and carbon-centered radicals, to understand the radical intermediates generated by enzymatic systems and more specifically lipoxygenases. Our methodology rests on the fact that free radicals react with the nitroxide phosphorus compound, 5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline-N-oxide (DIPPMPO), to form stable radical adducts, which are suitably detected and accurately quantified using (31)P NMR in the presence of a phosphorus containing internal standard. This system was thus applied to better understand the mechanism of enzymatic oxidation of linoleic acid by soybean lipoxygenases-1 (LOX). The total amount of radicals trapped by DIPPMPO was detected by (31)P NMR at different experimental conditions. In particular the effect of dioxygen concentration on the amount of radicals being trapped was studied. At low dioxygen concentration, a huge increase of radicals trapped was observed with respect to the amount of radicals being trapped at normal dioxygen concentrations.}, number={9}, journal={Bioorganic & Medicinal Chemistry}, publisher={Elsevier BV}, author={Zoia, Luca and Perazzini, Raffaella and Crestini, Claudia and Argyropoulos, Dimitris S.}, year={2011}, month={May}, pages={3022–3028} }
 @article{king_jalomaki_granstrom_argyropoulos_heikkinen_kilpelainen_2010, title={A new method for rapid degree of substitution and purity determination of chloroform-solulble cellulose esters, using P-31 NMR}, volume={2}, ISSN={["1759-9679"]}, DOI={10.1039/c0ay00336k}, abstractNote={Chloroform-soluble palmitic and decanoic acid esters of cellulose were synthesized from the reaction of MCC with acid chlorides in LiCl/DMA and the ionic liquid [amim]Cl, as novel cellulose solvents. A process of derivatization of the remaining hydroxyl groups, as phosphite esters and subsequent 31P NMR analysis, allowed for simultaneous degree of substitution (DS) determination and quantification of the aqueous-quench acid by-product impurity, after the appropriate calculation. The full mathematical treatment for DS determination is presented, including scripts for the Python and Java programming languages for rapid interpretation of results. This method for DS determination was validated against traditional analyses of the palmitoyl cellulose and the fully substituted p-nitrobenzoyl palmitoyl diester product, from additional reaction with p-nitrobenzoyl chloride. DOSY NMR and SCORE analyses were also employed to demonstrate the utility of this rapid 31P derivatization and analytical process over traditional 1D NMR analyses.}, number={10}, journal={ANALYTICAL METHODS}, author={King, Alistair W. T. and Jalomaki, Jarno and Granstrom, Mari and Argyropoulos, Dimitris S. and Heikkinen, Sami and Kilpelainen, Ilkka}, year={2010}, month={Oct}, pages={1499–1505} }
 @article{li_filpponen_argyropoulos_2010, title={Acidolysis of Wood in Ionic Liquids}, volume={49}, ISSN={["0888-5885"]}, DOI={10.1021/ie1000983}, abstractNote={Three wood species including Eucalyptus grandis (E. grandis), Southern pine (S. pine), and Norway spruce thermomechanical pulp (N. spruce TMP) were dissolved in the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl), and then they were pretreated with small amounts of hydrochloric acid, as a function of time. The materials regenerated from the IL solutions were determined to contain significantly higher amounts of lignin than the original wood. Detailed analyses of the recovered IL revealed the presence of typical wood degradation compounds, such as 5-hydroxymethylfurfural, furan-2-carboxylic acid, catechol, methylcatechol, methylguaiacol, acetoguaiacone, and acetol. The acidic pretreatment of these wood species in IL resulted in not only the near-complete hydrolysis of cellulose and hemicelluloses but also in a significant amount of lignin degradation. Aqueous reactions (under identical acid concentrations) showed a remarkably lower efficiency, demonstrating that ILs offer a unique environment for the acid-catalyzed dehydration chemistry, which is known to occur when polysaccharides and/or wood are subjected to an acid treatment.}, number={7}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Li, Bin and Filpponen, Ilari and Argyropoulos, Dimitris S.}, year={2010}, month={Apr}, pages={3126–3136} }
 @article{zoia_argyropoulos_2010, title={Characterization of free radical spin adducts of 5-diisopropyloxy-phosphoryl-5-methyl-1-pyrroline-N-oxide using mass spectrometry and P-31 nuclear magnetic resonance}, volume={16}, ISSN={["1469-0667"]}, DOI={10.1255/ejms.1062}, abstractNote={5-Diisopropyloxy-phosphoryl-5-methyl-1-pyrroline- N-oxide (DIPPMPO) was used to trap a variety of free radicals and the stable compounds generated by the natural decomposition of the initially formed spin adducts were characterized by 31 P nuclear magnetic resonance (NMR) and mass spectrometry. Initially, the starting spin trap DIPPMPO was completely characterized using GC-MS and its fragmentation pathway was studied in detail. Then, DIPPMPO was used to trap an oxygen-centered free radical (the hydroxyl radical • OH) and two carbon-centered free radicals (methyl • CH 3 and 1-phenyl-ethanol-1-yl • CCH 3 (OH)Ph radicals). The 31 P NMR signals were thus assigned and the structures of adducts were studied and confirmed by mass spectrometry. Overall, the fragmentation pathways of the radical adducts proceed mainly via the loss of the diisopropyloxy(oxido)phosphoranyl radical. For the specific case of trapping·OH radicals, it is possible to visualize the rearrangement of the nitroxide radical adduct to its nitrone form as invoked in the literature. This spin trapping technique, coupled with 31 P NMR and MS, provides a tool for the identification of short-lived and low molecular weight free radicals present in a variety of processes.}, number={2}, journal={EUROPEAN JOURNAL OF MASS SPECTROMETRY}, author={Zoia, Luca and Argyropoulos, Dimitris S.}, year={2010}, pages={175–185} }
 @article{zoia_argyropoulos_2010, title={Detection of ketyl radicals using P-31 NMR spin trapping}, volume={23}, ISSN={["0894-3230"]}, DOI={10.1002/poc.1630}, abstractNote={Our recent work has allowed the development of 31P NMR spin trapping techniques for the detection and, at times, absolute quantification of many oxygen- and carbon-centered free radical species. These methods are based on the ability of the nitrone phosphorus compound, 5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline-N-oxide (DIPPMPO), to react with free radical species and form stable radical adducts, which are suitably detected and accurately quantified using 31P NMR. Our continuing efforts have now been focused on the application of this powerful system for the trapping of ketyl radicals, which are very difficult intermediates to be detected and quantified with traditional techniques (i.e., EPR). Ketyl radicals were initially produced using photochemical reactions of acetophenone, whose excited triplet state is able to abstract hydrogen from an H donor. As such, the 31P NMR signals for the radical adducts of the DIPPMPO spin trap with the ketyl radicals were assigned. Furthermore, in an effort to confirm the structure of these adducts, their mass spectra and fragmentation patterns were carefully examined under Gas Chromatography–Mass Spectrometry (GC–MS) conditions. Subsequently, the DIPPMPO spin trapping system was applied to the oxidation of 1-(3,4-dimethoxyphenyl)ethanol in the presence of horseradish peroxidase (HRP), hydrogen peroxide, and 1-hydroxybenzotriazole (HBT) as the electron carrier (mediator). Our work confirmed that the mechanism consists of a hydrogen abstraction reaction from the α position, involving the ketyl radical: during the oxidation, the hydroxyl, hydroperoxyl, and ketyl radical intermediates were all detected. These efforts demonstrate the efficacy of our methodology that provides for the first time a facile means for the detection of the otherwise elusive ketyl radical species, with important implications in biology, chemistry, and biochemistry. Copyright © 2009 John Wiley & Sons, Ltd.}, number={6}, journal={JOURNAL OF PHYSICAL ORGANIC CHEMISTRY}, author={Zoia, Luca and Argyropoulos, Dimitris S.}, year={2010}, month={Jun}, pages={505–512} }
 @article{li_asikkala_filpponen_argyropoulos_2010, title={Factors Affecting Wood Dissolution and Regeneration of Ionic Liquids}, volume={49}, ISSN={["0888-5885"]}, DOI={10.1021/ie901560p}, abstractNote={Three wood species, eucalyptus grandis (E. grandis), southern pine (S. pine), and Norway spruce thermomechanical pulp (N. spruce TMP) were pretreated by dissolution in the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). The wood was regenerated from the ionic liquid in high yield and the recycling of the ionic liquid was nearly quantitative. The lignin contents and the efficiencies of cellulase enzymatic hydrolyses of the regenerated wood were examined offering an understanding into the IL pretreatment efficiency. The components that remained within the recycled ILs were qualitatively characterized by 31P NMR spectroscopy. Wood density, pulverization intensity, and the nature of the regeneration nonsolvents were investigated as factors affecting the overall process. An increase in the wood density decreased the efficiency of the pretreatment, whereas extended pulverization periods decreased the yield of the regenerated wood after the IL pretreatment,with more glucose being released during the enzymatic hydrolysis. The yield of wood after IL pretreatment using water as the regeneration nonsolvent was found to be much higher than that of using methanol. As the reuse cycles of IL increased the wood regeneration yield increased, while certain wood components enriched within the recycled IL. The efficiency of cellulase enzymatic hydrolysis on the regenerated wood decreased with increasing reuse cycles of the IL.}, number={5}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Li, Bin and Asikkala, Janne and Filpponen, Ilari and Argyropoulos, Dimitris S.}, year={2010}, month={Mar}, pages={2477–2484} }
 @article{hu_heitmann_rojas_pawlak_argyropoulos_2010, title={Monitoring Cellulase Protein Adsorption and Recovery Using SDS-PAGE}, volume={49}, ISSN={0888-5885 1520-5045}, url={http://dx.doi.org/10.1021/ie100731b}, DOI={10.1021/ie100731b}, abstractNote={Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was employed to study the sorption behaviors of cellulases on microcrystalline celluloses and hardwood pulp. The adsorption and recovery of cellulases from Aspergillus niger and Trichoderma reesei were investigated at 25 °C. Cellulase recovery was conducted by rinsing adsorbed enzymes with sodium acetate buffer, Milli-Q water, and sodium hydroxide solution. The initial, equilibrium, and recovered enzymes were analyzed using SDS-PAGE gels. Gels were scanned and analyzed using ImagePro software. The molecular weights of cellulase proteins were determined using a protein marker having seven known proteins. The cellulase system from Trichoderma reesei had a higher adsorption on all substrates studied than the cellulase system from Aspergillius niger, and higher pH favored desorption from the substrates studied. Experimental results also demonstrated that adsorption and desorption amounts determined by SDS-PAGE were proportional to protein concentrations in their crude mixtures.}, number={18}, journal={Industrial & Engineering Chemistry Research}, publisher={American Chemical Society (ACS)}, author={Hu, Gang and Heitmann, John A., Jr. and Rojas, Orlando J. and Pawlak, Joel J. and Argyropoulos, Dimitris S.}, year={2010}, month={Sep}, pages={8333–8338} }
 @article{filpponen_argyropoulos_2010, title={Regular Linking of Cellulose Nanocrystals via Click Chemistry: Synthesis and Formation of Cellulose Nanoplatelet Gels}, volume={11}, ISSN={["1526-4602"]}, DOI={10.1021/bm1000247}, abstractNote={Over a number of years work in our laboratory has been developing new chemistry for the use of cellulose nanocrystals (CNCs) as scaffolds for the creation of nanomaterials with novel, stimuli responsive characteristics. Our work takes advantage of the rigid nature of CNCs, the unique nanopattern etched on their surface in the form of regularly spaced primary OH groups, and the fact that these materials have all reducing end groups located on one end. In this communication, a method for the grafting of amine-terminated monomers onto surface-modified CNCs followed by click chemistry is demonstrated. Initially the primary hydroxyl groups on the surface of the CNCs were selectively activated by converting them to carboxylic acids by the use of TEMPO-mediated hypohalite oxidation. Further reactions using the activated TEMPO-oxidized CNCs were carried out via carbodiimide-mediated formation of an amide linkage between precursors carrying an amine functionality and the carboxylic acid groups on the surface of the TEMPO-oxidized CNCs. Subsequently, two sets of CNCs were prepared, containing on their surface an azide derivative and an alkyne derivative, respectively. Finally, the click chemistry reaction, that is, the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition between the azide and the alkyne, surface-activated CNC was employed, bringing together the nanocrystalline materials in a unique regularly packed arrangement demonstrating a degree of molecular control for creating these structures at the nano level.}, number={4}, journal={BIOMACROMOLECULES}, author={Filpponen, Ilari and Argyropoulos, Dimitris S.}, year={2010}, month={Apr}, pages={1060–1066} }
 @article{potamitis_zervou_katsiaras_zoumpoulakis_durdagi_papadopoulos_hayes_grdadolnik_kyrikou_argyropoulos_et al._2009, title={Antihypertensive Drug Valsartan in Solution and at the AT1 Receptor: Conformational Analysis, Dynamic NMR Spectroscopy, in Silico Docking, and Molecular Dynamics Simulations}, volume={49}, ISSN={1549-9596 1549-960X}, url={http://dx.doi.org/10.1021/ci800427s}, DOI={10.1021/ci800427s}, abstractNote={The conformational properties of AT1 antagonist valsartan have been analyzed both in solution and at the binding site of the receptor. Low energy conformations of valsartan in solution were explored by NMR spectroscopy and molecular modeling studies. The NMR results showed the existence of two distinct and almost isoenergetic conformations for valsartan (cis:trans ratio around the amide bond approximately 40:60) that coalesce at the temperature range of 55-60 degrees C in agreement with previous in solution conformational analysis study (Fang et al. Magn. Reson. Chem. 2007, 45, 929-936). Quantum mechanics and ONIOM calculations revealed that the bulky valsartan substituents actually contribute to stabilization of the transition state for interconversion. In silico docking and Molecular Dynamic studies were applied to study binding of valsartan at the AT1 receptor site models, explicitly solvated and embedded in lipid bilayers and solvent molecules. These studies revealed that the majority of docked poses adopted a trans (major) conformation. Of paramount and maybe biological importance are the MD simulations results which showed that the two acidic groups of valsartan are bridged through LYS199 enabling it for multiple hydrogen bond interactions. In a lipid bilayer environment these interactions are enhanced, designating the important role of lipid bilayers for the better binding of valsartan and its stabilization at the active site.}, number={3}, journal={Journal of Chemical Information and Modeling}, publisher={American Chemical Society (ACS)}, author={Potamitis, Constantinos and Zervou, Maria and Katsiaras, Vassilis and Zoumpoulakis, Panagiotis and Durdagi, Serdar and Papadopoulos, Manthos G. and Hayes, Joseph M. and Grdadolnik, Simona Golic and Kyrikou, Ioanna and Argyropoulos, Dimitris and et al.}, year={2009}, month={Mar}, pages={726–739} }
 @article{soriano_venditti_argyropoulos_2009, title={Biodiesel synthesis via homogeneous Lewis acid-catalyzed transesterification}, volume={88}, ISSN={0016-2361}, url={http://dx.doi.org/10.1016/j.fuel.2008.10.013}, DOI={10.1016/j.fuel.2008.10.013}, abstractNote={Abstract Lewis acids (AlCl 3 or ZnCl 2 ) were used to catalyze the transesterification of canola oil with methanol in the presence of terahydrofuran (THF) as co-solvent. The conversion of canola oil into fatty acid methyl esters was monitored by 1 H NMR. NMR analysis demonstrated that AlCl 3 catalyzes both the esterification of long chain fatty acid and the transesterification of vegetable oil with methanol suggesting that the catalyst is suitable for the preparation of biodiesel from vegetable oil containing high amounts of free fatty acids. Optimization by statistical analysis showed that the conversion of triglycerides into fatty acid methyl esters using AlCl 3 as catalyst was affected by reaction time, methanol to oil molar ratio, temperature and the presence of THF as co-solvent. The optimum conditions with AlCl 3 that achieved 98% conversion were 24:1 molar ratio at 110 °C and 18 h reaction time with THF as co-solvent. The presence of THF minimized the mass transfer problem normally encountered in heterogeneous systems. ZnCl 2 was far less effective as a catalyst compared to AlCl 3 , which was attributed to its lesser acidity. Nevertheless, statistical analysis showed that the conversion with the use of ZnCl 2 differs only with reaction time but not with molar ratio.}, number={3}, journal={Fuel}, publisher={Elsevier BV}, author={Soriano, Nestor U., Jr. and Venditti, Richard and Argyropoulos, Dimitris S.}, year={2009}, month={Mar}, pages={560–565} }
 @article{kim_montero_habibi_hinestroza_genzer_argyropoulos_rojas_2009, title={Dispersion of Cellulose Crystallites by Nonionic Surfactants in a Hydrophobic Polymer Matrix}, volume={49}, ISSN={["1548-2634"]}, DOI={10.1002/pen.21417}, abstractNote={Cellulose nanoparticles obtained by acid hydrolysis of cellulose paper were used to reinforce polystyrene composite films. The nonionic surfactant sorbitan monostearate was utilized to improve the dispersion properties of the hydrophilic cellulose in hydrophobic matrix and to prevent the formation of aggregates. Turbidity tests were used to measure dispersion stability of the cellulose crystallites in the hydrophobic solvent used in the composite manufacture. A correlation was found between the dispersion stability in solvent and the formation of aggregates in the polymeric composites. Nanocomposite films were processed using a casting/evaporation technique. Thermal and mechanical properties of processed composites were studied by differential scanning calorimetry (DSC) and dynamical mechanical analyses (DMA), respectively. The results showed that the optimum addition of surfactant produced better dispersion of the cellulose particles in the polystyrene matrix and improved the mechanical properties of the resulting composite due to an enhanced compatibility. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers}, number={10}, journal={POLYMER ENGINEERING AND SCIENCE}, author={Kim, Jooyoun and Montero, Gerardo and Habibi, Youssef and Hinestroza, Juan P. and Genzer, Jan and Argyropoulos, Dimitris S. and Rojas, Orlando J.}, year={2009}, month={Oct}, pages={2054–2061} }
 @article{xie_jarvi_karesoja_king_kilpelainen_argyropoulos_2009, title={Highly Compatible Wood Thermoplastic Composites from Lignocellulosic Material Modified in Ionic Liquids: Preparation and Thermal Properties}, volume={111}, ISSN={["1097-4628"]}, DOI={10.1002/app.29251}, abstractNote={A study of converting chemically modified wood into thermoplastic materials was undertaken to develop a new technology platform for the effective utilization of wood-based lignocellulosic materials. Highly substituted benzoylated spruce thermomechanical pulp (TMP) and lauroylated spruce TMP were used as components for thermoplastic composites of poly(styrene) and poly(propylene). Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) were used to characterize the interfacial morphology and thermal properties of the resultant composite filaments. The coupling of the interfacial morphology effort and that of torque analysis applied during processing indicated that the thorough modification of wood fibers by benzoylation and/or lauroylation reactions can improve the compatibility between the wood-based lignocellulosic materials and poly(styrene) and poly(propylene). Thermal analysis showed that, with the addition of wood derivatives into poly(styrene) and poly(propylene) matrices, a slight decrease in their Tgs was observed. Furthermore, all of the prepared composites showed improved thermal stability, as revealed by TGA. The resultant thermoplastic wood composites exhibited good melting properties and were readily extruded into filaments or sheets. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009}, number={5}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Xie, Haibo and Jarvi, Paula and Karesoja, Mikko and King, Alistair and Kilpelainen, Ilkka and Argyropoulos, Dimitris S.}, year={2009}, month={Mar}, pages={2468–2476} }
 @article{king_kilpelainen_heikkinen_jarvi_argyropoulos_2009, title={Hydrophobic Interactions Determining Functionalized Lignocellulose Solubility in Dialkylimidazolium Chlorides, as Probed by P-31 NMR}, volume={10}, ISSN={["1526-4602"]}, DOI={10.1021/bm8010159}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVNoteHydrophobic Interactions Determining Functionalized Lignocellulose Solubility in Dialkylimidazolium Chlorides, as Probed by 31P NMRAlistair W. T. King†, Ilkka Kilpeläinen†, Sami Heikkinen†, Paula Järvi†, and Dimitris S. Argyropoulos*‡View Author Information Laboratory of Organic Chemistry, Department of Chemistry, Faculty of Science, University of Helsinki, Helsinki, Finland, and Organic Chemistry of Wood Components Laboratories, Department of Forest Biomaterials, College of Natural Resources, North Carolina State University, Raleigh, North Carolina* To whom correspondence should be addressed. E-mail: [email protected]†University of Helsinki.‡North Carolina State University.Cite this: Biomacromolecules 2009, 10, 2, 458–463Publication Date (Web):December 18, 2008Publication History Received10 September 2008Revised19 November 2008Published online18 December 2008Published inissue 9 February 2009https://doi.org/10.1021/bm8010159Copyright © 2008 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views1027Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (787 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Anions,Biopolymers,Cellulose,Hydrophobicity,Solvents Get e-Alerts}, number={2}, journal={BIOMACROMOLECULES}, author={King, Alistair W. T. and Kilpelainen, Ilkka and Heikkinen, Sami and Jarvi, Paula and Argyropoulos, Dimitris S.}, year={2009}, month={Feb}, pages={458–463} }
 @article{king_zoia_filpponen_olszewska_xie_kilpelainen_argyropoulos_2009, title={In Situ Determination of Lignin Phenolics and Wood Solubility in Imidazolium Chlorides Using P-31 NMR}, volume={57}, ISSN={["1520-5118"]}, DOI={10.1021/jf901095w}, abstractNote={Corn stover, Norway spruce, and Eucalyptus grandis were pulverized to different degrees. These samples were subjected to quantitative analyses, upon the basis of predissolution into the imidazolium chloride-based ionic liquids [amim]Cl and [bnmim]Cl followed by labeling of hydroxyl groups as phosphite esters and quantitative (31)P NMR analysis. Analysis of different pulverization degrees provided semiempirical data to chart the solubility of Norway spruce in these ionic liquids. Further method refinment afforded an optimized method of analysis of the lignin phenolic functionalities, without prior isolation of the lignin from the fiber. The lignin in these samples was further enriched using cellulase and acidolysis treatments, allowing for comparison with the fibrous samples. Analysis of all samples charts the polymerized-monomer availability for each stage of the treatment. Conditions required for adequate signal-to-noise ratios in the (31)P NMR analysis were established with a notable improvement observed upon the lignin enrichment steps.}, number={18}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={King, Alistair W. T. and Zoia, Luca and Filpponen, Ilari and Olszewska, Anna and Xie, Haibo and Kilpelainen, Ilkka and Argyropoulos, Dimitris S.}, year={2009}, month={Sep}, pages={8236–8243} }
 @article{zoia_argyropoulos_2009, title={Phenoxy radical detection using P-31 NMR spin trapping}, volume={22}, ISSN={["1099-1395"]}, DOI={10.1002/poc.1561}, abstractNote={Recent work in our laboratory has allowed the development of quantitative 31P NMR spin trapping techniques. These methods have been demonstrated to be effective tools for the detection and absolute quantification of many oxygen- and carbon-centered free radical species. Our methods rest on the fact that a free radical reacts with the nitroxide phosphorus compound, 5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline-N-oxide (DIPPMPO), to form stable radical adducts, which are suitably detected and accurately quantified using 31P NMR in the presence of phosphorus containing internal standards. This system was applied for the detection of phenoxy radicals, as an alternative to traditional EPR techniques. More specifically, the phenoxy radicals were produced via the oxidation of different phenols by K3Fe(CN)6. The 31P NMR signals for the radical adducts of phenoxy radicals (PhO·) were assigned and found to be located at 25.2 ppm. Subsequently, this spin trapping system was applied to the oxidation of various phenols in the presence of peroxidases and 1-hydroxybenzotriazole (HBT) as a mediator: the 2,4,6-trichlorophenol and 2,4,6-tri-tert-butylphenol were oxidized and only phenoxy radical adducts were detected, whereas during the oxidation of 2,4-dimethylphenol and isoeugenol, other adducts were detected and related to radical delocalization. These preliminary efforts demonstrate the efficacy of our methodologies, so that a variety of radical species can now be readily detected and quantified using quantitative 31P NMR spin trapping techniques. Copyright © 2009 John Wiley & Sons, Ltd.}, number={11}, journal={JOURNAL OF PHYSICAL ORGANIC CHEMISTRY}, author={Zoia, Luca and Argyropoulos, Dimitris S.}, year={2009}, month={Nov}, pages={1070–1077} }
 @article{mattinen_filpponen_jarvinen_li_kallio_lehtinen_argyropoulos_2009, title={Structure of the Polyphenolic Component of Suberin Isolated from Potato (Solanum tuberosum var. Nikola)}, volume={57}, ISSN={["1520-5118"]}, DOI={10.1021/jf9020834}, abstractNote={Suberin is present in the underground parts of vegetables and in the bark of trees. Characterization of suberin and the structure of its polyphenolic component have been hampered by insolubility of the polymers. Thus, enzymatically isolated and extractive free suberin enriched fraction from potato, Solanum tuberosum var. Nikola, and the chemically further fractionated phenolics were characterized in solid state by FTIR, DSC, and elemental analysis to identify the groups and to verify success of isolation. For MW and quantitative determination of the groups, polymers were solubilized in ionic liquid derivatized and analyzed by GPC and 31P NMR. Suberin enriched fraction, MW = ca. 44 × 103 g/mol, is a mixture of carbohydrates and polyesters of aliphatic long chain hydroxy fatty acids and diacids linked via ester bonds to the phenolics, MW = ca. 27 × 103 g/mol, formed by guaiacyl- and p-hydroxyphenyl structures. Phenolics in peels may be important sources of antioxidants for various applications.}, number={20}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Mattinen, Maija-Liisa and Filpponen, Ilari and Jarvinen, Riika and Li, Bin and Kallio, Heikki and Lehtinen, Pekka and Argyropoulos, Dimitris}, year={2009}, month={Oct}, pages={9747–9753} }
 @article{popescu_singurel_popescu_vasile_argyropoulos_willfor_2009, title={Vibrational spectroscopy and X-ray diffraction methods to establish the differences between hardwood and softwood}, volume={77}, ISSN={["1879-1344"]}, DOI={10.1016/j.carbpol.2009.03.011}, abstractNote={FT-IR spectrometry and X-ray diffraction were applied to probe the differences between pulp fibers from Eucalyptus wood (hardwood) and Norway spruce wood (softwood). Wood processing was found to induce certain structural alterations within its components depending on the type of wood and the applied procedure. These differences were established by using techniques such as; spectral comparison of wood samples with those of individual component fractions, derivative spectroscopy, bands deconvo- lution, etc. FT-IR spectroscopy was shown to be an important tool that provided details about the struc- tural characteristics of hardwood and softwood samples. Using second-derivative spectra and deconvolution processes small differences between spectra became apparent that allowed correlations to be made related to wood composition. In addition a correlation was established between the integral absorptions for the various bands and lignin content as well as the lignin/carbohydrate content. Relations between various spectral characteristics and the degree of crystallinity and sample composition were established.}, number={4}, journal={CARBOHYDRATE POLYMERS}, author={Popescu, Carmen-Mihaela and Singurel, Ghita and Popescu, Maria-Cristina and Vasile, Cornelia and Argyropoulos, Dimitris S. and Willfor, Stefan}, year={2009}, month={Jul}, pages={851–857} }
 @article{filpponen_argyropoulos_2008, title={Determination of Cellulose Reactivity by Using Phosphitylation and Quantitative P-31 NMR Spectroscopy}, volume={47}, ISSN={["0888-5885"]}, DOI={10.1021/ie800936x}, abstractNote={The phosphitylation of cellulose with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane [P(II)], is proposed as a means to determine its reactivity via an evaluation of its accessible hydroxyl groups. A variety of cellulose samples were subjected to this phosphitylation reaction, and the consumption of phosphitylation reagent was followed by quantitative 31P NMR spectroscopy. This consumption was found to be directly proportional to the amount of reactive hydroxyl groups on the cellulosic material. To further evaluate the quantitative reliability of this methodology, cellulose samples were subjected to a series of mechanical beating treatments, and the changes in the amount of accessible OH groups were evaluated. In addition, cellulose samples were equilibrated to various moisture contents, and their accessible OH groups were determined using the developed methodology. Both variables examined were found to affect the amount of reactive OH groups present on the samples with variations in the moisture content having a greater effect. For example, up to 6.5 mmol g−1, of accessible OH groups were found to be created within the highly refined samples at the highest moisture content.}, number={22}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Filpponen, Ilari and Argyropoulos, Dimitris S.}, year={2008}, month={Nov}, pages={8906–8910} }
 @article{guerra_norambuena_freer_argyropoulos_2008, title={Determination of arylglycerol-beta-aryl ether linkages in enzymatic mild acidolysis lignins (EMAL): Comparison of DFRC/P-31 NMR with thioacidolysis}, volume={71}, ISSN={["1520-6025"]}, DOI={10.1021/np800080s}, abstractNote={Enzymatic mild acidolysis lignins (EMAL) isolated from different species of softwood and Eucalyptus globulus were submitted to comparative analysis that included thioacidolysis, derivatization followed by reductive cleavage (DFRC), and DFRC followed by quantitative (31)P NMR (DFRC/(31)P NMR). While gas chromatography (GC) was used to determine the monomer yields from both thioacidolysis and DFRC, (31)P NMR studies quantified the various phenolic hydroxy groups released by DFRC. The monomer yields from thioacidolysis and DFRC were substantially different, with thioacidolysis resulting in higher yields. In contrast, an excellent agreement was obtained in the total number of beta-aryl ether structures determined by thioacidolysis and DFRC/(31)P NMR, indicating that the combination of DFRC with quantitative (31)P NMR overcomes, at least in part, the limitations presented by the DFRC method. Both thioacidolysis and DFRC/(31)P NMR were further used to better understand the lignin isolation process from wood. The results show that mild rotary ball milling minimizes, but does not prevent, the degradation of beta-O-4 structures during the early stages of wood pulverization. The extent of such degradation was found to be higher for E. globulus than for a variety of softwoods examined. Furthermore, the structures of the EMALs isolated at yields ranging from 20% to 62% were very similar, indicating structural homogeneity in the lignin biopolymer within the secondary wall.}, number={5}, journal={JOURNAL OF NATURAL PRODUCTS}, author={Guerra, Anderson and Norambuena, Marcela and Freer, Juanita and Argyropoulos, Dimitris S.}, year={2008}, month={May}, pages={836–841} }
 @article{luca_argyropoulos_2008, title={Development of quantitative 31P NMR methods for the trapping of phenoxy & ketyl free radicals}, volume={74}, ISSN={0032-0943 1439-0221}, url={http://dx.doi.org/10.1055/s-0028-1083915}, DOI={10.1055/s-0028-1083915}, number={09}, journal={Planta Medica}, publisher={Georg Thieme Verlag KG}, author={Luca, Z and Argyropoulos, DS}, year={2008}, month={Jul} }
 @article{guerra_lucia_argyropoulos_2008, title={Isolation and characterization of lignins from Eucalyptus grandis Hill ex Maiden and Eucalyptus globulus Labill. by enzymatic mild acidolysis (EMAL)}, volume={62}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2008.004}, abstractNote={Abstract Despite the growing importance of Eucalyptus wood as raw material for pulp and paper, there is a lack of knowledge on the chemistry of their macromolecular components. The present paper addresses this issue by applying the recently developed protocol for isolating enzymatic mild acidolysis lignins (EMAL) from Eucalyptus grandis , Eucalyptus globulus and the softwood species Douglas fir and white fir, which were used for comparative purposes. The structures of EMALs were investigated by quantitative 31 P NMR, DFRC/ 31 P NMR (derivatization followed by reductive cleavage followed by quantitative 31 P NMR) and size exclusion chromatography (SEC). Overall, the yields of EMALs isolated from Eucalyptus were higher than those from the softwoods examined. Lignin from E. globulus was found to contain higher contents of arylglycerol- β -aryl ether structures, free phenolic hydroxyl groups and syringyl-type units than lignin from E. grandis . New insights provided by the DFRC/ 31 P NMR revealed that up to 62.2% of arylglycerol- β -aryl ether structures in E. globulus are uncondensed, while in E. grandis the amount of such uncondensed structures was found to be lower than 48%. SEC analyses showed that lignins from E. grandis and softwoods associate in greater extension than lignin from E. globulus .}, number={1}, journal={HOLZFORSCHUNG}, author={Guerra, Anderson and Lucia, Lucian A. and Argyropoulos, Dimitris S.}, year={2008}, pages={24–30} }
 @article{zoia_orlandi_argyropoulos_2008, title={Microwave-Assisted Lignin Isolation Using the Enzymatic Mild Acidolysis (EMAL) Protocol}, volume={56}, ISSN={["1520-5118"]}, DOI={10.1021/jf801955b}, abstractNote={The use of microwaves is explored in an effort to further improve the recently developed lignin isolation protocol termed EMAL (enzymatic mild acidolysis lignin). Because the presence of the lignin-carbohydrate linkages seems to be rather pronounced within wood, a microwave reactor was used to replace traditional refluxing during the mild acidolysis step. This was done in an attempt to augment the selectivity of this step toward cleaving lignin-carbohydrate bonds as well as reducing the overall intensity of this step toward inducing changes in the lignin structure, thus affording lignin in greater yields and purities. Consequently, in this study the yields, purities, and structures of lignins isolated from spruce (softwood) by the EMAL protocol under various microwave conditions were examined. The variables studied included microwave power, microwave heating time, hydrochloric acid concentration and water content of the reaction medium. Microwave heating afforded EMAL samples of high purity (90%, comparable to the conventional protocol) but in significantly greater gravimetric yields. Quantitative (31)P NMR and SEC data confirmed that the structure of lignin was similar to that obtained by traditional EMALs, with comparable contents of beta-aryl ether bonds, phenolic hydroxyls (condensed and uncondensed), and carboxylic acids.}, number={21}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Zoia, Luca and Orlandi, Marco and Argyropoulos, Dimitris S.}, year={2008}, month={Nov}, pages={10115–10122} }
 @article{contreras_gaspar_guerra_lucia_argyropoulos_2008, title={Propensity of Lignin to Associate: Light Scattering Photometry Study with Native Lignins}, volume={9}, ISSN={["1526-4602"]}, DOI={10.1021/bm800673a}, abstractNote={Many studies of lignins in solution invoke association and aggregation phenomena to explain their solution behavior (e.g., reprecipitation onto pulp fibers, condensation, etc.). Following their colloidal (apparent) molecular weights in solution as a function of time allows us to explore observable dissociation phenomena. These measurements were carried out using multiple angle laser light scattering (MALLS) photometry in the static mode. The challenges and opportunities of measuring the specific refractive index increment (dn/dC) of lignin solutions and determining the kinetics of the dissociation process were thus investigated. Hardwood and softwood representative lignins were isolated, and method for their full dissolution in THF was further developed, which then lead to accurate dn/dC values being obtained as a function of time. When coupled to additional work using light scattering static measurements and Zimm plots for the same solutions, this effort offers insight into the aggregation and ensuing dissociative events that operate within the lignin macromolecules.}, number={12}, journal={BIOMACROMOLECULES}, author={Contreras, Sofia and Gaspar, Armindo R. and Guerra, Anderson and Lucia, Lucian A. and Argyropoulos, Dimitris S.}, year={2008}, month={Dec}, pages={3362–3369} }
 @article{soriano_venditti_saquing_bushey_argyropoulos_2008, title={Solubilizing amino acids and polypeptides in supercritical CO2 via reverse micelle formation}, volume={315}, ISSN={0927-7757}, url={http://dx.doi.org/10.1016/j.colsurfa.2007.07.019}, DOI={10.1016/j.colsurfa.2007.07.019}, abstractNote={Water-in-CO2 reverse micelles stabilized by ionic perfluoroalkyl and non-ionic perfluoropolyether surfactants were used to host amino acids and polypeptides in supercritical (SC) CO2. The minimum pressure at which micellization occurs (Ptrans) was found to be affected by the surfactant concentration and H2O/CO2 ratio. Due to the differences in hydrophilic/CO2 balance, the two surfactants exhibited different phase behaviors at 19.3 MPa and 40 °C. At certain H2O/CO2/surfactant compositions, while coagulation was more evident when using perfluoroalkyl surfactant, flocculation was found to dominate the system containing perfluoropolyether surfactant. The presence of amino acid and polypeptide in reverse micelles was found to increase the Ptrans of the system due to enthalpic and entropic changes. In perfluoroalkyl reverse micelles, the Ptrans was found to increase with increasing hydrophilicity of the amino acid added. The presence of hydrophobic moieties in amino acids promotes interfacial solubilization that eventually resulted in lower Ptrans. On the other hand, the nature of the amino acid was not found to affect Ptrans in perfluoropolyether reverse micelle. Overall, this work demonstrates that polypeptides with varying molecular weight could be solubilized in water-in-CO2 reverse micelles using perfluoropolyether while perfluoroakyl surfactants were ineffective.}, number={1-3}, journal={Colloids and Surfaces A: Physicochemical and Engineering Aspects}, publisher={Elsevier BV}, author={Soriano, Nestor U., Jr. and Venditti, Richard and Saquing, Carl D. and Bushey, Dean and Argyropoulos, Dimitris S.}, year={2008}, month={Feb}, pages={110–116} }
 @article{granstrom_kavakka_king_majoinen_makela_helaja_hietala_virtanen_maunu_argyropoulos_et al._2008, title={Tosylation and acylation of cellulose in 1-allyl-3-methylimidazolium chloride}, volume={15}, ISSN={["0969-0239"]}, DOI={10.1007/s10570-008-9197-5}, number={3}, journal={CELLULOSE}, author={Granstrom, Mari and Kavakka, Jari and King, Alistair and Majoinen, Johanna and Makela, Valtteri and Helaja, Juho and Hietala, Sami and Virtanen, Tommi and Maunu, Sirkka-Liisa and Argyropoulos, Dimitris S. and et al.}, year={2008}, month={Jun}, pages={481–488} }
 @article{fu_argyropoulos_tilotta_lucia_2008, title={Understanding the pyrolysis of CCA-treated wood Part I. Effect of metal ions}, volume={81}, ISSN={["1873-250X"]}, DOI={10.1016/j.jaap.2007.08.003}, abstractNote={The influence of several inorganic compounds (K2Cr2O7, CrO3 and CuSO4) on the pyrolysis of southern pine wood has been investigated. The wood powder was pre-treated with various inorganic compound solutions prior to the pyrolysis and the distribution and yields of the pyrolysis products were obtained by gas chromatography and quantitative 31P nuclear magnetic resonance (NMR) analyses. Our experiments showed that K2Cr2O7 and CuSO4 salts promoted the formation of levoglucosan (LG). In particular, the former providing higher LG yields up to 26.7%. The CrO3 treatment induced the production of low tar and high char yields, with a very low yield of LG and high yield of levoglucosenone (LGO). The underlying reasoning behind these findings may be due to an acidic catalysis mechanism, which promotes cellulose depolymerization and dehydration processes. Due to acid-catalyzed lignin condensation reactions, the yield of lignin degradation products from the pyrolysis of pre-treated wood was found to dramatically decrease in comparison to untreated wood.}, number={1}, journal={JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS}, author={Fu, Qirong and Argyropoulos, Dimitris S. and Tilotta, David C. and Lucia, Lucian A.}, year={2008}, month={Jan}, pages={60–64} }
 @article{fu_argyropoulos_tilotta_lucia_2008, title={Understanding the pyrolysis of CCA-treated wood. Part II. Effect of phosphoric acid}, volume={82}, ISSN={["1873-250X"]}, DOI={10.1016/j.jaap.2008.02.007}, abstractNote={The pyrolysis process of chromated copper arsenate-treated wood impregnated with phosphoric acid (2–6 wt.%) has been investigated using a Kugelrohr short-path distillation apparatus. The presence of phosphoric acid is shown to change the overall pyrolysis kinetics and yields of products resulting in a decrease in the amount of volatile products and an increase in the char formation. The yield of levoglucosan was found to decrease in the presence of relatively higher concentrations of phosphoric acid, while the yield of levoglucosenone increased. The pyrolysis of chromated copper arsenate-treated wood in the presence of phosphoric acid gave rise to 22% (on water-free tar basis) levoglucosenone. Such data demonstrates the potential for a new pathway toward the rational utilization of chromated copper arsenate-treated wood waste.}, number={1}, journal={JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS}, author={Fu, Qirong and Argyropoulos, Dimitris S. and Tilotta, David C. and Lucia, Lucian A.}, year={2008}, month={May}, pages={140–144} }
 @article{adamopoulos_montegna_hampikian_argyropoulos_heitmann_lucia_2007, title={A simple method to tune the gross antibacterial activity of cellulosic biomaterials}, volume={69}, ISSN={["1879-1344"]}, DOI={10.1016/j.carbpol.2007.02.019}, abstractNote={A very preliminary approach for grossly tuning the antibacterial activity of cellulosic fibers has been developed and its preliminary findings are described herein. The approach is universal for cellulosic-based substrates and first involves a physico-chemical adsorption phenomenon between fatty acid methyl esters (FAMEs) and cellulose. The cellulose biomaterials were in the form of disks 2 cm in diameter that were subjected to standard agar growth plates containing a gamut of gram positive and gram negative bacteria. Zones of inhibition were measured around the biomaterials which displayed a broad spectrum of antibacterial activity. This activity could be tuned simply by grossly changing the surface area of the cellulosic surface topology as indicated by the surface fibrillation of the microfibrils and hence the bioactive availability of the fatty acids. Thus, the potential application of these materials in the biomedical field appears promising.}, number={4}, journal={CARBOHYDRATE POLYMERS}, author={Adamopoulos, Lambrini and Montegna, Jason and Hampikian, Greg and Argyropoulos, Dimitris S. and Heitmann, John and Lucia, Lucian A.}, year={2007}, month={Jul}, pages={805–810} }
 @article{saladino_fiani_crestini_argyropoulos_marini_coletta_2007, title={An efficient and stereoselective dearylation of asarinin and sesamin tetrahydrofurofuran lignans to acuminatolide by methyltrioxorhenium/H2O2 and UHP systems}, volume={70}, ISSN={["1520-6025"]}, DOI={10.1021/np060479u}, abstractNote={The synthesis of stereoisomers of acuminatolide is rare and requires complex and time-consuming multistep procedures. Asarinin (1) and sesamin (2), two diasteromeric tetrahydrofurofuran lignans, are efficiently mono-dearylated by methyltrioxorhenium (MTO, I) and hydrogen peroxide (H2O2) or urea hydrogen peroxide adduct (UHP) as primary oxidant to give (-)-(7R,8'R,8R)-acuminatolide (3A) and (+)-(7S,8R,8'R)-acuminatolide (3B), respectively, in high yield and diastereoselectivity (de >98%). The oxidation of 1 was also performed with novel heterogeneous catalysts based on the heterogenation of MTO on poly(4-vinylpyridine) and polystyrene resins. In these latter cases 3A was obtained with a different yield and selectivity depending on the physical-chemical properties of the support. Cytotoxic effects of 3A and 3B in mammalian cell lines in vitro are also reported.}, number={1}, journal={JOURNAL OF NATURAL PRODUCTS}, author={Saladino, Raffaele and Fiani, Cinzia and Crestini, Claudia and Argyropoulos, Dimitris S. and Marini, Stefano and Coletta, Massimiliano}, year={2007}, month={Jan}, pages={39–42} }
 @article{hubbe_rojas_argyropoulos_wang_song_sulic_sezaki_2007, title={Charge and the dry-strength performance of polyampholytes. Part 2. Colloidal effects}, volume={301}, DOI={10.1016/j.colsurfa.2006.11.053}, abstractNote={Polyampholytes, which are macromolecules that contain both positive and negative ionizable groups, can provide superior strength improvements for paper manufacture, compared to the addition of simple polyelectrolytes. Colloidal effects, which were measured in solution and in fiber suspensions, were consistent with observed bonding effects. The same colloidal effects were found to correlate with the effects of pH and of the density of the ionizable groups on the polyampholytes. Tests were carried out with a series of polyampholytes having a constant ratio of cationic to anionic monomeric groups and molecular mass. Their charge density varied in the ratio 1:2:4:8. The greatest strength gains were obtained at intermediate charge density and under conditions of pH favoring instability of the aqueous polymer mixtures. Colloidal phenomena were elucidated by turbidimetric tests, sediment volumes of treated fiber suspensions, flocculation tendencies of treated fiber suspensions, and zeta potentials of probe particles.}, journal={Colloids and Surfaces. A, Physicochemical and Engineering Aspects}, author={Hubbe, M. A. and Rojas, O. J. and Argyropoulos, Dimitris and Wang, Y. and Song, J. and Sulic, N. and Sezaki, T.}, year={2007}, pages={23–32} }
 @article{wang_hubbe_rojas_argyropoulos_wang_sezaki_2007, title={Charge and the dry-strength performance of polyampholytes. Part 3: Streaming potential analysis}, volume={301}, ISSN={["1873-4359"]}, DOI={10.1016/j.colsurfa.2006.11.052}, abstractNote={Results reported in Part 1 of this series showed that paper strength improvements could be optimized by varying pH and the overall content of ionic groups in random terpolymers containing a fixed molar ratio of acidic and basic monomeric groups. Further treatment of kraft fiber slurries with polyaluminum chloride (PAC), after polyampholyte addition, yielded significant strength benefits. The present paper shows how these results can be explained in terms of the streaming potential (SP) of glass fibers, which were used as a model substrate. The data suggest that aluminum ions interact both with the anionic carboxyl groups of the polyampholytes and with anionic silanol groups at fiber surfaces. The streaming potential of the treated surfaces could be changed by varying the pH, the overall density of charged groups of the polyampholytes, the ratio of cationic to anionic groups on the polymer and by post-treatment with polyaluminum chloride.}, number={1-3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Wang, Yun and Hubbe, Martin A. and Rojas, Orlando J. and Argyropoulos, Dimitris S. and Wang, Xingwu and Sezaki, Takao}, year={2007}, month={Jul}, pages={33–40} }
 @inbook{lucian_argyropoulos_adamopoulos_gaspar_2007, title={Chemicals & energy from forest biomass: A review}, volume={954}, ISBN={9780841239814}, DOI={10.1021/bk-2007-0954.ch001}, abstractNote={There are approximately 89 million metric tonnes of organic chemicals and lubricants produced annually in the United States (1). The majority of these are fossil fuel-based materials that have the potential to become environmental pollutants during use and that carry end-of-life cycle concerns such as disposal, pollution, and degradation. As a result, the need to decrease pollution caused by petrochemical usage is currently impelling the development of green technologies. It is virtually inarguable that the dwindling hydrocarbon economy will eventually become unsustainable. The cost of crude oil continues to increase, while agricultural products see dramatic decreases in world market prices. TTiese trends provide sufficient basis for renewed interest in the use of biomass as a feedstock and for the development of a lignocellulosic-based economy as the logical alternative to fossil fuel resources.}, booktitle={Materials, chemicals and energy from forest biomass}, publisher={Washington, DC: ACS Books}, author={Lucian, A. L. and Argyropoulos, Dimitris and Adamopoulos, L. and Gaspar, A. R.}, year={2007}, pages={2–30} }
 @article{kilpelainen_xie_king_granstrom_heikkinen_argyropoulos_2007, title={Dissolution of wood in ionic liquids}, volume={55}, ISSN={["1520-5118"]}, DOI={10.1021/jf071692e}, abstractNote={The present paper demonstrates that both hardwoods and softwoods are readily soluble in various imidazolium-based ionic liquids (ILs) under gentle conditions. More specifically, a variety of ionic liquids can only partially dissolve wood chips, whereas ionic liquids such as 1-butyl-3-methylimidazolium chloride and 1-allyl-3-methylimidazolium chloride have good solvating power for Norway spruce sawdust and Norway spruce and Southern pine thermomechanical pulp (TMP) fibers. Despite the fact that the obtained solutions were not fully clear, these ionic liquids provided solutions which permitted the complete acetylation of the wood. Alternatively, transparent amber solutions of wood could be obtained when the dissolution of the same lignocellulosic samples was attempted in 1-benzyl-3-methylimidazolium chloride. This realization was based on a designed augmented interaction of the aromatic character of the cation of the ionic liquid with the lignin in the wood. After dissolution, wood can be regenerated as an amorphous mixture of its original components. The cellulose of the regenerated wood can be efficiently digested to glucose by a cellulase enzymatic hydrolysis treatment. Furthermore, completely acetylated wood was found to be readily soluble in chloroform, allowing, for the first time, detailed proton nuclear magnetic resonance (NMR) spectra and NMR diffusion measurements to be made. It was thus demonstrated that the dissolution of wood in ionic liquids now offers a variety of new possibilities for its structural and macromolecular characterization, without the prior isolation of its individual components. Furthermore, considering the relatively wide solubility and compatibility of ionic liquids with many organic or inorganic functional chemicals or polymers, it is envisaged that this research could create a variety of new strategies for converting abundant woody biomass to valuable biofuels, chemicals, and novel functional composite biomaterials.}, number={22}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Kilpelainen, Ilkka and Xie, Haibo and King, Alistair and Granstrom, Mari and Heikkinen, Sami and Argyropoulos, Dimitris S.}, year={2007}, month={Oct}, pages={9142–9148} }
 @inbook{rojas_bullon_ysambertt_a._d. s._salager_2007, title={Lignin as emulsion stabilizers: Materials, chemicals and energy from forest biomass}, volume={954}, ISBN={9780841239814}, booktitle={Materials, chemicals and energy from forest biomass}, publisher={Washington, DC: ACS Books}, author={Rojas, O. J. and Bullon, J. and Ysambertt, F. Forgiarini and A., Argyropoulos and D. S. and Salager, J.-L.}, year={2007}, pages={182–199} }
 @inbook{rojas_jheong_turon_argyropoulos_2007, title={Measurement of cellulase activity with piezoelectric resonators}, volume={954}, ISBN={9780841239814}, booktitle={Materials, chemicals and energy from forest biomass}, publisher={Washington, DC: ACS Books}, author={Rojas, O. J. and Jheong, C. and Turon, X. and Argyropoulos, D. S.}, year={2007}, pages={478–494} }
 @inbook{lucian_argyropoulos_ban_song_2007, title={Modifying the functionality of starch films with natural polymers}, volume={954}, ISBN={9780841239814}, DOI={10.1021/bk-2007-0954.ch013}, abstractNote={The physical and chemical properties of composite starch-based films containing cellulosic fiber, chitosan, and gelatin were investigated. Films containing both cellulosic fibers and chitosan demonstrated tremendous enhancements in film strength and gas permeation. The water absorbency of composite films could be greatly reduced in film composites containing cellulosic fibers and gelatin, but the inclusion of chitosan into these films provided a higher hydrophilicity, increasing water absorbency. Film transparency was not noticeably affected in the composite films that were made. These films may have wide application in the food packaging, agricultural mulching, and the biomedical industries.}, booktitle={Materials, chemicals and energy from forest biomass}, publisher={Washington, DC: ACS Books}, author={Lucian, A. L. and Argyropoulos, Dimitris and Ban, W. and Song, J.}, year={2007}, pages={200–218} }
 @article{guerra_gaspar_contreras_lucia_crestini_argyropoulos_2007, title={On the propensity of lignin to associate: A size exclusion chromatography study with lignin derivatives isolated from different plant species}, volume={68}, ISSN={["0031-9422"]}, DOI={10.1016/j.phytochem.2007.05.026}, abstractNote={Despite evidence that lignin associates under both aqueous and organic media, the magnitude and nature of the underlying driving forces are still a matter of discussion. The present paper addresses this issue by examining both solution properties and size exclusion behaviour of lignins isolated from five different species of softwoods, as well as from the angiosperms Eucalyptus globulus and wheat straw. This investigation has used the recently described protocol for isolating enzymatic mild acidolysis lignin (EMAL), which offers lignin samples highly representative of the overall lignin present in the wood cell wall. The molecular weight distributions of these EMALs were found to be dependent upon the wood species from which they were isolated and upon the incubation conditions used prior to size exclusion chromatography. While the chromatograms of EMALs isolated from softwoods displayed a bimodal behaviour, the elution profiles of EMAL from E. globulus and straw were nearly unimodal. A marked tendency to dissociate prevailed under incubation at room temperature for all examined species with the exception of the straw lignin preparation; furthermore, lignin solutions incubated at 4 degrees C showed an associative behaviour manifested by an increase in the weight and number average molecular weights for some species. The extent of such association/dissociation, as well as the time needed for the process to reach completion, was also found to depend upon the wood species, i.e. lignins from softwoods were found to associate/dissociate to a greater extent than lignins from E. globulus and straw. The origin of such effects within the lignin structure is also discussed.}, number={20}, journal={PHYTOCHEMISTRY}, author={Guerra, Anderson and Gaspar, Armindo R. and Contreras, Soffa and Lucia, Lucian A. and Crestini, Claudia and ArgyropouloS, Dimitris S.}, year={2007}, month={Oct}, pages={2570–2583} }
 @inbook{argyropoulos_saquing_gaspar_soriano_lucia_rojas_2007, title={Oxidative chemistry of lignin In supercritical carbon dioxide & expanded liquids}, volume={954}, ISBN={9780841239814}, DOI={10.1021/bk-2007-0954.ch020}, abstractNote={This chapter describes the use of supercritical carbon dioxide (scCO2) and scCO2-expanded liquids, as reaction media for the oxidative fragmentation of lignin using hydrogen peroxide as the oxidant. Kraft Indulin Lignin (KIL) is oxidized with peroxide in neat scCO2 but more extensive oxidation occurs in scCO2-expanded liquids, selectively inducing the formation of large amounts of carboxylic acids via the elimination of phenolic moieties. Interestingly, the weight average molecular weight of the lignin oxidized in neat scCO2 decreased while it increased in scCO2-expanded liquid, most likely via the preferential elimination of the lower molecular weight fragments. Notably, all these significant oxidative transformations occur in total absence of alkali, which is essential when such reactions occur in aqueous media.}, booktitle={Materials, chemicals and energy from forest biomass}, publisher={Washington, DC: ACS Books}, author={Argyropoulos, Dimitris and Saquing, C. D. and Gaspar, A. R. and Soriano, N. U. and Lucia, L. A. and Rojas, O. J.}, year={2007}, pages={311–331} }
 @article{fu_argyropoulos_tilotta_lucia_2007, title={Products and functional group distributions in pyrolysis oil of chromated copper arsenate (CCA)-Treated wood, as elucidated by gas chromatography and a novel P-31 NMR-Based method}, volume={46}, ISSN={["0888-5885"]}, DOI={10.1021/ie0702274}, abstractNote={Low-temperature pyrolysis offers a feasible option for wood waste management and the recovery of a variety of useful chemicals. In this study, the effect of chromated copper arsenate (CCA) wood preservatives on the yield and composition of various pyrolysis products was investigated over the temperature range of 275−350 °C. For this preliminary work, we examined the feasibility of using gas chromatography coupled with either flame ionization detection or mass spectroscopic detection and a novel 31P nuclear magnetic resonance (NMR) spectroscopic method. Both methods worked well, with the gas chromatographic method being compound-specific and the 31P NMR method being specific to the functional group (e.g., aliphatic alcohols, total phenols, and carboxylic acids). The present experiments showed that the CCA treatment on wood had a significant effect on the amount of main carbohydrate degradation products of tar. The yield of levoglucosan (LG) from CCA-treated wood increased, while the yields of hydroxyacetaldehyde and hydroxyacetone decreased.}, number={16}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Fu, Qirong and Argyropoulos, Dimitris S. and Tilotta, David C. and Lucia, Lucian A.}, year={2007}, month={Aug}, pages={5258–5264} }
 @article{popescu_popescu_singurel_vasile_argyropoulos_willfor_2007, title={Spectral characterization of eucalyptus wood}, volume={61}, ISSN={["1943-3530"]}, DOI={10.1366/000370207782597076}, abstractNote={The main difficulties in wood and pulp analyses arise principally from their numerous components with different chemical structures. Therefore, the basic problem in a specific analytical procedure may be the selective separation of the main carbohydrate-derived components from lignin due to their chemical association and structural coexistence. The processing of the wood determines some structural modification in its components depending on the type of wood and the applied procedure. Fourier transform infrared (FT-IR) spectrometry and X-ray diffraction have been applied to analyze Eucalyptus g. wood chips and unbleached and chlorite-bleached pulp. The differences between samples have been established by examination of the spectra of the fractions obtained by successive extraction (acetone extractives, acetone free extractive samples, hemicelluloses, and lignins) by evaluating the derivative spectra, band deconvolution, etc. The energy and the hydrogen bonding distance have been evaluated. The relationship between spectral characteristics and sample composition has been established, as well as the variation of the degree of crystallinity after pulping and bleaching. The integral absorption and lignin/carbohydrate ratios calculated from FT-IR spectra of the IR bands assigned to different bending or stretching in lignin groups are stronger in the spectrum of eucalyptus chips than those from brown stock (BS) pulp spectra because of the smaller total amount of lignin in the latter. FT-IR spectra clearly show that after chlorite bleaching the structure of the wood components is partially modified or removed. Along with FT-IR data, the X-ray results confirmed the low content of lignin in the pulp samples by increasing the calculated values of the crystalline parameters. It was concluded that FT-IR spectroscopy can be used as a quick method to differentiate Eucalyptus globulus samples.}, number={11}, journal={APPLIED SPECTROSCOPY}, author={Popescu, Carmen-Mihaela and Popescu, Maria-Cristina and Singurel, Ghita and Vasile, Cornelia and Argyropoulos, Dimitris S. and Willfor, Stefan}, year={2007}, month={Nov}, pages={1168–1177} }
 @article{xie_king_kilpelainen_granstrom_argyropoulos_2007, title={Thorough chemical modification of wood-based lignocellulosic materials in ionic liquids}, volume={8}, ISSN={["1526-4602"]}, DOI={10.1021/bm700679s}, abstractNote={Homogenous acylation and carbanilation reactions of wood-based lignocellulosic materials have been investigated in ionic liquids. We have found that highly substituted lignocellulosic esters can be obtained under mild conditions (2 h, 70 degrees C) by reacting wood dissolved in ionic liquids with acetyl chloride, benzoyl chloride, and acetic anhydride in the presence of pyridine. In the absence of pyridine, extensive degradation of the wood components was found to occur. Highly substituted carbanilated lignocellulosic material was also obtained in the absence of base in ionic liquid. These chemical modifications were confirmed by infrared spectroscopy, (1)H NMR, and quantitative (31)P NMR of the resulting derivatives. The latter technique permitted the degrees of substitution to be determined, which were found to vary between 81% and 95% for acetylation, benzoylation, and carbanilation, accompanied by similarly high gains in weight percent values. Thermogravimetric measurements showed that the resulting materials exhibit different thermal stabilities from those of the starting wood, while differential scanning calorimetry showed discrete new thermal transitions for these derivatives. Scanning electron microscopy showed the complete absence of fibrous characteristics for these derivatives, but instead, a homogeneous porous, powdery appearance was apparent. A number of our reactions were also carried out in completely recycled ionic liquids, verifying their utility for potential applications beyond the laboratory bench.}, number={12}, journal={BIOMACROMOLECULES}, author={Xie, Haibo and King, Alistair and Kilpelainen, Ilkka and Granstrom, Mari and Argyropoulos, Dimitris S.}, year={2007}, month={Dec}, pages={3740–3748} }
 @article{wang_hubbe_sezaki_wang_rojas_argyropoulos_2006, title={Aspects of retention and formation - The role of polyampholyte charge density on its interactions with cellulose}, volume={21}, number={5}, journal={Nordic Pulp & Paper Research Journal}, author={Wang, Y. and Hubbe, M. A. and Sezaki, T. and Wang, X. W. and Rojas, O. J. and Argyropoulos, D. S.}, year={2006}, pages={638–645} }
 @article{lucia_argyropoulos_adamopoulos_gaspar_2006, title={Chemicals and energy from biomass}, volume={84}, ISSN={["1480-3291"]}, DOI={10.1139/V06-117}, abstractNote={Approximately 89 million metric tonnes of organic chemicals and lubricants are produced annually in the United States (T.M. Carole, J. Pellegrino, and M.D. Paster. Appl. Biochem. Biotechnol. 115, 871 (2004)). The majority of these materials are fossil fuel based and may load the environment during use and at the end of their life cycle. Issues, such as disposal, pollution, and degradation, must be considered and weighed. As a result, the need to decrease pollution caused by petrochemical usage is currently impelling the development of green technologies. It is virtually inarguable that the dwindling hydrocarbon economy will eventually become unsustainable. The cost of crude oil continues to increase, while agricultural products see dramatic decreases in world market prices. These trends provide sufficient basis for renewed interest in the use of biomass as a feedstock and for the development of a carbohydrate-based economy as the logical alternative to fossil fuel resources.Key words: biomass, biochemicals, natural products, bioenergy.}, number={7}, journal={CANADIAN JOURNAL OF CHEMISTRY}, author={Lucia, Lucian A. and Argyropoulos, Dimitris S. and Adamopoulos, Lambrini and Gaspar, Armindo R.}, year={2006}, month={Jul}, pages={960–970} }
 @article{sezaki_hubbe_heitmann_argyropoulos_wang_2006, title={Colloidal effects of acrylamide polyampholytes - Part 1. Electrokinetic behavior}, volume={281}, ISSN={["1873-4359"]}, DOI={10.1016/j.colsurfa.2006.02.019}, abstractNote={The colloidal and electrokinetic behavior of three amphoteric acrylamide-based water-soluble terpolymers of high molecular mass was elucidated in terms of their structure and composition, using potentiometric and colloidal titrations, as well as microelectrophoresis, viscometry, and turbidity measurements. Independent variables included polymer composition, pH, and the concentration of salt ions. The electrokinetic properties, titratable charge, and isoelectric pH values of the samples were compared to their monomeric composition, as confirmed by NMR and FTIR analysis. The electrophoretic mobilities of the polyampholytes changed relatively rapidly with pH in the neighborhood of the isoelectric pH values, consistent with an enrichment of excess charges toward the outer parts of the macromolecules. Interactions of the polyampholytes with highly-charged titrants appeared to be less pH-dependent, in the neighborhood of the isoelectric condition, relative to a linear prediction based on the numbers of acidic and basic macromolecular groups. Specific viscosity measurements, in the vicinity of the isoelectric point, were found to increase with increasing salt concentration, which is a typical anti-polyelectrolyte behavior. In a similar manner, salt addition suppressed the development of a turbidity maximum at the isoelectric point.}, number={1-3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Sezaki, Takao and Hubbe, Martin A. and Heitmann, John A. and Argyropoulos, Dimitris S. and Wang, Xingwu}, year={2006}, month={Jun}, pages={74–81} }
 @article{sezaki_hubbe_heitmann_argyropoulos_2006, title={Colloidal effects of acrylamide polyampholytes - Part 2: Adsorption onto cellulosic fibers}, volume={289}, ISSN={["0927-7757"]}, DOI={10.1016/j.colsurfa.2006.04.010}, abstractNote={Colloidal titrations of commercial acrylamide-based terpolymers having both weak-acidic and weak-basic groups were carried out at pH 3 and 11, using a streaming current technique. At these pH values it was found that the polyampholytes could be considered as simple polyelectrolytes, though it was necessary to use a modified titration procedure. The titration endpoint defined by zero streaming current (SC) output deviated from a 1:1 stoichiometry, depending on the salt concentration. The endpoint also depended at the speed of titration, consistent with a relatively slow rate of forming equilibrated poly-ion complexes between polyampholytes and titrants. The adsorption of the amphoteric polyacrylamide copolymers onto bleached hardwood fibers was maximized near to its iso-electric pH, such that the net charge of the polymer was relatively low, but opposite to that of the substrate. Neutral and negatively charged polyampholytes also adsorbed in significant amounts onto the negatively charged fibers, though the amounts were lower than when the net charges were opposite. Addition of salt generally increased adsorption up to a conductivity value of 1000 μS/cm. Adsorption increased slightly with increasing time, until reaching a plateau. The rate of fluid agitation during adsorption did not affect adsorption significantly under the conditions employed.}, number={1-3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Sezaki, Takao and Hubbe, Martin A. and Heitmann, John A. and Argyropoulos, Dimitris S.}, year={2006}, month={Oct}, pages={89–95} }
 @article{guerra_filpponen_lucia_argyropoulos_2006, title={Comparative evaluation of three lignin isolation protocols for various wood species}, volume={54}, ISSN={["1520-5118"]}, DOI={10.1021/jf062433c}, abstractNote={Milled wood lignin (MWL), cellulolytic enzyme lignin (CEL), and enzymatic mild acidolysis lignin (EMAL) were isolated from different wood species and characterized by various techniques. The EMAL protocol offered gravimetric lignin yields 2-5 times greater than those of the corresponding MWL and CEL. The purities of the EMALs were 3.75-10.6% higher than those of their corresponding CELs, depending upon the wood species from which they were isolated. Molecular weight analyses showed that the EMAL protocol isolates lignin fractions that are not accessed by the other procedures evaluated, while 31P NMR spectroscopy revealed that MWL is more condensed and bears more phenolic hydroxyl groups than EMAL and CEL. The yields and purities of EMAL, MWL, and CEL from hardwood were greater than those obtained for the examined softwoods. Structural details obtained by DFRC (derivatization followed by reductive cleavage)/31P NMR revealed different contents of condensed and uncondensed beta-O-aryl ether structures, dibenzodioxocins, and condensed and uncondensed phenolic hydroxyl and carboxylic acid groups within lignins isolated from different wood species.}, number={26}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Guerra, Anderson and Filpponen, Ilari and Lucia, Lucian A. and Argyropoulos, Dimitris S.}, year={2006}, month={Dec}, pages={9696–9705} }
 @article{crestini_caponi_argyropoulos_saladino_2006, title={Immobilized methyltrioxo rhenium (MTO)/H2O2 systems for the oxidation of lignin and lignin model compounds}, volume={14}, ISSN={["1464-3391"]}, DOI={10.1016/j.bmc.2006.03.046}, abstractNote={A convenient and efficient application of heterogeneous methylrhenium trioxide (MTO) systems for the selective oxidation of lignin model compounds and lignins is reported. Environmental friendly and low-cost H2O2 was used as the oxygen atom donor. Overall, the data presented and discussed in this paper point toward the conclusion that the immobilized heterogeneous catalytic systems based on H2O2/and MTO catalysts are able to extensively oxidize both phenolic and non-phenolic, monomeric, and dimeric, lignin model compounds. Condensed diphenylmethane models were found also extensively oxidized. Technical lignins, such as hydrolytic sugar cane lignin (SCL) and red spruce kraft lignin (RSL), displayed oxidative activity with immobilized MTO catalytic systems. After oxidation, these lignins displayed the formation of more soluble lignin fragments with a high degree of degradation as indicated by the lower contents of aliphatic and condensed OH groups, and the higher amounts of carboxylic acid moieties. Our data indicate that immobilized MTO catalytic systems are significant potential candidates for the development of alternative totally chlorine-free delignification processes and environmental sustainable lignin selective modification reactions.}, number={15}, journal={BIOORGANIC & MEDICINAL CHEMISTRY}, author={Crestini, Claudia and Caponi, Maria Chiara and Argyropoulos, Dimitris S. and Saladino, Raffaele}, year={2006}, month={Aug}, pages={5292–5302} }
 @article{ban_jianguosong_argyropous_lucia_2006, title={Improving the physical and chemical functionality of starch-derived films with biopolymers}, volume={100}, ISSN={["1097-4628"]}, DOI={10.1002/app.23698}, abstractNote={The physical and chemical properties of composite starch-based films containing cellulosic fiber, chitosan, and gelatin were investigated. Films containing both cellulosic fibers and chitosan demonstrated tremendous enhancements in film strength and gas permeation. The water absorbency of composite films could be greatly reduced in film composites containing cellulosic fibers and gelatin, but the inclusion of chitosan into these films provided a higher hydrophilicity, increasing water absorbency. Film transparency was not noticeably affected in the composite films that were made. These films may have wide application in the food packaging, agricultural mulching, and the medical industries. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2542–2548, 2006}, number={3}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Ban, WP and JianguoSong and Argyropous, DS and Lucia, LA}, year={2006}, month={May}, pages={2542–2548} }
 @article{ban_song_argyropoulos_lucia_2006, title={Influence of natural biomaterials on the elastic properties of starch-derived films: An optimization study}, volume={45}, ISSN={["0888-5885"]}, DOI={10.1021/ie050219s}, abstractNote={A D-optimization design was applied to investigate the strength properties of biomaterial-doped starch films. The individual effect of each additive and associated interactive effects were investigated. Cellulosic fibers and chitosan were able to substantially enhance film strength. Lignin and gelatin also demonstrated significant interactive effects on strength, while different interactive effects were evident between the major biopolymers (fiber and chitosan) and minor biopolymers (lignin and gelatin). The film stretch depended on the material composition where diminishing returns were observed for stretch, while strength increased for increasing levels of each of the biopolymers. An increase in fiber and chitosan contents led to increases in film density that correlated well with strength. The latter data indicate that fiber and chitosan biopolymers act synergistically by providing increased film bonding that eventually generates a stronger film.}, number={2}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Ban, WP and Song, JG and Argyropoulos, DS and Lucia, LA}, year={2006}, month={Jan}, pages={627–633} }
 @article{rojas_song_argyropoulos_2006, title={Lignin separation from kraft black liquors by tangential ultrafiltration}, volume={88}, number={1}, journal={Chimica E L'industria}, author={Rojas, O. J. and Song, J. and Argyropoulos, D. S.}, year={2006}, pages={88–95} }
 @article{argyropoulos_li_gaspar_smith_lucia_rojas_2006, title={Quantitative P-31 NMR detection of oxygen-centered and carbon-centered radical species}, volume={14}, ISSN={["1464-3391"]}, DOI={10.1016/j.bmc.2006.02.009}, abstractNote={In this study, quantitative 31 P NMR spin trapping techniques were used as effective tools for the detection and quantification of many free radical species. The radicals react with 5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline- N -oxide (DIPPMPO) producing stable spin adducts, which can be detected and accurately quantified using 31 P NMR spectroscopy. This effort forms the foundations for the understanding of the nature, identity, and mechanisms of radical activity in a variety of biological and biochemical reactions involving radical processes. Quantitative 31 P NMR spin trapping techniques can be used as effective tools for the detection and quantification of many free radical species. Free radicals react with a nitroxide phosphorus compound, 5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline- N -oxide (DIPPMPO), to form stable radical adducts, which are suitably detected and accurately quantified using 31 P NMR in the presence of phosphorus containing internal standards. Initially, the 31 P NMR signals for the radical adducts of oxygen-centered ( OH, O 2 − ) and carbon-centered ( CH 3 , CH 2 OH, CH 2 CH 2 OH) radicals were assigned. Subsequently, the quantitative reliability of the developed technique was demonstrated under a variety of experimental conditions. The 31 P NMR chemical shifts for the hydroxyl and superoxide reaction adducts with DIPPMPO were found to be 25.3, 16.9, and 17.1 ppm (in phosphate buffer), respectively. The 31 P NMR chemical shifts for CH 3 , CH 2 OH, CH(OH)CH 3 , and C(O)CH 3 spin adducts were 23.1, 22.6, 27.3, and 30.2 ppm, respectively. Overall, this effort forms the foundations for a targeted understanding of the nature, identity, and mechanisms of radical activity in a variety of biomolecular processes.}, number={12}, journal={BIOORGANIC & MEDICINAL CHEMISTRY}, author={Argyropoulos, Dimitris S. and Li, Hongyang and Gaspar, Armindo R. and Smith, Kamilah and Lucia, Lucian A. and Rojas, Orlando J.}, year={2006}, month={Jun}, pages={4017–4028} }
 @article{filpponen_guerra_hai_lucia_argyropoulos_2006, title={Spectral monitoring of the formation and degradation of polysulfide ions in alkaline conditions}, volume={45}, ISSN={["0888-5885"]}, DOI={10.1021/ie060651p}, abstractNote={The recently developed protocol for the absolute determination of the various polysulfide species based by 1H NMR was applied to monitor the amount of such ions in alkaline media produced at different conditions. The thermal stability of each individual polysulfide species was also evaluated in temperature ranges representative of a typical alkaline pulping process. Overall, the species, S12-, S22-, S32-, S42-, S52-, and S62- were detected and quantified in all alkaline conditions evaluated. The concentration of sodium sulfide and the temperature were found to have a significant effect on the total amount of polysulfides detected. In summary, the di- and trisulfide anions were found to predominate over the other polysulfide species in all examined experimental conditions. Additionally, the experimental values of Ea for the thermal degradation of polysulfide species correlate with the observed stability of the individual species; i.e., S22- has the highest Ea, followed by S32-.}, number={22}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Filpponen, Ilari and Guerra, Anderson and Hai, Abdul and Lucia, n A. Lucia and Argyropoulos, Dimitris S.}, year={2006}, month={Oct}, pages={7388–7392} }
 @article{argyropoulos_gaspar_lucia._j._2006, title={Supercritical CO2 oxidation of lignin: Production of high valued added products}, volume={88}, number={1}, journal={Chimica E L'industria}, author={Argyropoulos, D. S. and Gaspar, A. and Lucia., L. and J., Rojas. O.}, year={2006}, pages={74–79} }
 @article{wang_hubbe_sezaki_wang_rojas_argyropoulos_2006, title={The role of polyampholyte charge density on its interactions with cellulose}, volume={21}, number={5}, journal={Nordic Pulp & Paper Research Journal}, author={Wang, Y. and Hubbe, M. A. and Sezaki, T. and Wang, X. and Rojas, O. J. and Argyropoulos, D. S.}, year={2006}, pages={158–165} }
 @article{guerra_filpponen_lucia_saquing_baumberger_argyropoulos_2006, title={Toward a better understanding of the lignin isolation process from wood}, volume={54}, ISSN={["1520-5118"]}, DOI={10.1021/jf060722v}, abstractNote={The recently developed protocol for isolating enzymatic mild acidolysis lignins (EMAL) coupled with the novel combination of derivatization followed by reductive cleavage (DFRC) and quantitative (31)P NMR spectroscopy were used to better understand the lignin isolation process from wood. The EMAL protocol is shown to offer access at lignin samples that are more representative of the overall lignin present in milled wood. The combination of DFRC/(31)P NMR provided a detailed picture on the effects of the isolation conditions on the lignin structure. More specifically, we have used vibratory and ball milling as the two methods of wood pulverization and have compared their effects on the lignin structures and molecular weights. Vibratory-milling conditions cause substantial lignin depolymerization. Lignin depolymerization occurs via the cleavage of uncondensed beta-aryl ether linkages, while condensed beta-aryl ethers and dibenzodioxocins were found to be resistant to such mechanical action. Condensation and side chain oxidations were induced mechanochemically under vibratory-milling conditions as evidenced by the increased amounts of condensed phenolic hydroxyl and carboxylic acid groups. Alternatively, the mild mechanical treatment offered by ball milling was found not to affect the isolated lignin macromolecular structure. However, the overall lignin yields were found to be compromised when the mechanical action was less intense, necessitating longer milling times under ball-milling conditions. As compared to other lignin preparations isolated from the same batch of milled wood, the yield of EMAL was about four times greater than the corresponding milled wood lignin (MWL) and about two times greater as compared to cellulolytic enzyme lignin (CEL). Molecular weight distribution analyses also pointed out that the EMAL protocol allows the isolation of lignin fractions that are not accessed by any other lignin isolation procedures.}, number={16}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Guerra, Anderson and Filpponen, Ilari and Lucia, Lucian A. and Saquing, Carl and Baumberger, Stephanie and Argyropoulos, Dimitris S.}, year={2006}, month={Aug}, pages={5939–5947} }
 @article{saariaho_argyropoulos_jaaskelainen_vuorinen_2005, title={Development of the partial least squares models for the interpretation of the UV resonance Raman spectra of lignin model compounds}, volume={37}, ISSN={["1873-3697"]}, DOI={10.1016/j.vibspec.2004.08.001}, abstractNote={Partial least squares (PLS) modeling was utilized for the interpretation of the ultraviolet resonance Raman (UVRR) spectra of various lignin model compounds. Lignin model compounds presented different structural characteristics of the naturally existing lignin biopolymer within wood materials. The model compounds were grouped according to their monomer type, condensed and conjugated structures. Condensed structures were defined as those having a side group at C5 carbon of the aromatic units. Conjugated model compounds were further subdivided into CC and CO as well as stilbene structures. PLS modeling was applied to find the characteristic Raman signals of each structure: p-hydroxyphenyl showed characteristic Raman bands at 1488, 1405, 1338, 1215, 1164, 1094, 861–841, 644 cm−1, guaiacyl at 1520, 1285–1270, 1186, 1124, 1078, 1024, 920, 784, 761, 711 cm−1, syringyl at 1588, 1510, 1331, 1228, 1148, 1108, 964, 810, 741 cm−1 condensed structures at 1618, 1558, 1492, 1375–1355, 1328, 1223, 975 cm−1, conjugated CC at 1658, 1538, 1475, 1311, 1215, 1130–1114, 974 cm−1, conjugated CO at 1695–1662, 1084 cm−1 and stilbenes at 1638, 1515, 1435–1421, 1263, 1191, 877, 768 cm−1. The loadings line spectra of different PLS models were further compared with the UVRR spectra of model compounds and hence, the feasibility of PLS modeling was verified. To the best of our knowledge, this is the first time when PLS modeling has been utilized in this manner for the interpretation of such spectra. The defined characteristic Raman bands can further be utilized for the interpretation of UVRR spectra of polymeric lignin samples. PLS models introduce new possibilities for the interpretation of Raman spectra since the UVRR spectral data of complex lignin samples contain broad bands which are cumbersome to fully identify.}, number={1}, journal={VIBRATIONAL SPECTROSCOPY}, author={Saariaho, AM and Argyropoulos, DS and Jaaskelainen, AS and Vuorinen, T}, year={2005}, month={Jan}, pages={111–121} }
 @article{argyropoulos_hou_ganesaratnam_harpp_koda_2005, title={Quantitative H-1 NMR analysis of alkaline polysulfide solutions}, volume={59}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2005.019}, abstractNote={Abstract A novel analytical protocol for the absolute determination of the various polysulfide species present in alkaline aqueous media was developed. The method is comprised of alkylating polysulfide ions with dimethyl sulfate, followed by quantitative proton NMR spectroscopy using 1,3,5-tributyl benzene as the internal standard. In order to arrive at a quantitative acquisition protocol, a number of variables were examined in detail for their effect on the alkylation reaction, including the presence of oxygen, the amount of dimethyl sulfate and sodium hydroxide, and the various modes of adding the alkylating reagent to the reaction mixture. Most of these variables were found to play a role in determining the quantitative reliability of the procedure. Consequently, a method is described that can be used for the efficient and reliable quantitative detection of polysulfide ions. The protocol developed could be particularly useful in promoting our understanding of the intricate and delicate chemistry of polysulfide equilibria in aqueous alkaline media.}, number={2}, journal={HOLZFORSCHUNG}, author={Argyropoulos, DS and Hou, YH and Ganesaratnam, R and Harpp, DN and Koda, K}, year={2005}, pages={124–131} }
 @article{chen_hubbe_heitmann_argyropoulos_rojas_2004, title={Dependency of polyelectrolyte complex stoichiometry on the order of addition - 2. Aluminum chloride and poly-vinylsulfate}, volume={246}, ISSN={["1873-4359"]}, DOI={10.1016/j.colsurfa.2004.07.021}, abstractNote={In the first part of this series it was shown that the stoichiometry of complexation between oppositely charged polyelectrolytes became increasingly dependent on the order of addition as the concentrations of monovalent and divalent ions were increased. This study considers the effect of aluminum ions on titrations between solutions of a strong poly-acid and a strong poly-base. In addition, the titratable charge of aluminum ion itself was also investigated. It was found that aluminum ions can interfere with the results of charge titrations, in the sense that the titration results became unpredictable. Stoichiometric relationships between the amount of aluminum present and the amount of titrant required to achieve streaming current values of zero were obtained only at pH values associated with a maximum in the amount of titrant needed to neutralize a given concentration of dissolved aluminum. The results are consistent with complexation between the anionic titrant and polynuclear species of aluminum, where the relative proportion of such species depends strongly on the molar ratio of OH to Al.}, number={1-3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Chen, JH and Hubbe, MA and Heitmann, JA and Argyropoulos, DS and Rojas, OJ}, year={2004}, month={Oct}, pages={71–79} }
 @article{chen_hubbe_heitmann_argyropoulos_rojas_2004, title={Dependency of polyelectrolyte complex stoichiometry on the order of addition2. Aluminum chloride and poly-vinylsulfate}, volume={246}, ISSN={0927-7757}, url={http://dx.doi.org/10.1016/S0927-7757(04)00458-3}, DOI={10.1016/S0927-7757(04)00458-3}, abstractNote={In the first part of this series it was shown that the stoichiometry of complexation between oppositely charged polyelectrolytes became increasingly dependent on the order of addition as the concentrations of monovalent and divalent ions were increased. This study considers the effect of aluminum ions on titrations between solutions of a strong poly-acid and a strong poly-base. In addition, the titratable charge of aluminum ion itself was also investigated. It was found that aluminum ions can interfere with the results of charge titrations, in the sense that the titration results became unpredictable. Stoichiometric relationships between the amount of aluminum present and the amount of titrant required to achieve streaming current values of zero were obtained only at pH values associated with a maximum in the amount of titrant needed to neutralize a given concentration of dissolved aluminum. The results are consistent with complexation between the anionic titrant and polynuclear species of aluminum, where the relative proportion of such species depends strongly on the molar ratio of OH to Al.}, number={1-3}, journal={Colloids and Surfaces A: Physicochemical and Engineering Aspects}, publisher={Elsevier BV}, author={Chen, J and Hubbe, M and Heitmann, J and Argyropoulos, D and Rojas, O}, year={2004}, month={Oct}, pages={71–79} }
 @article{argyropoulos_suchy_akim_2004, title={Nitrogen-centered activators of peroxide-reinforced oxygen delignification}, volume={43}, ISSN={["0888-5885"]}, DOI={10.1021/ie030372r}, abstractNote={In an effort to augment the efficiency of an oxygen delignification stage, we examined the effectiveness of various heterocyclic aromatic nitrogen compounds as possible activators of such a stage. It was shown that a variety of such compounds may act as activators in the presence of hydrogen peroxide, improving the delignification efficiency of oxygen delignification. Among the group of activators examined, 1,10-phenanthroline was found to be the most potent. Injecting the activator in the middle of the delignification stage (simulating a two-stage process) was shown to provide most of the benefits. The optimum injection time was found to at 30 min from the onset of the delignification. At the optimal charge of 1,10-phenanthroline (0.3%), the delignification was improved by 18%. While the presence of copper ions was found to further improve the efficiency of the activating system, this was accompanied by an extensive carbohydrate degradation.}, number={5}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Argyropoulos, DS and Suchy, M and Akim, L}, year={2004}, month={Mar}, pages={1200–1205} }
 @article{wu_argyropoulos_2003, title={An  improved method for isolating lignin in high yield and purity}, volume={29}, number={7}, journal={Journal of Pulp and Paper Science}, author={Wu, S. and Argyropoulos, D. S.}, year={2003}, month={Jul}, pages={235–240} }
 @article{crestini_jurasek_argyropoulos_2003, title={On the mechanism of the laccase-mediator system in the oxidation of lignin}, volume={9}, ISSN={["1521-3765"]}, DOI={10.1002/chem.200304818}, abstractNote={In an effort to elucidate the role of phenolic and non-phenolic lignin subunits in a laccase mediator (LM) system, vanillyl alcohol was oxidized with laccase in the presence and absence of the mediator 1-hydroxybenzotriazol (HBT). Furthermore, the role of phenolic, aliphatic hydroxyl, and carboxylic acid moieties in lignin degradation was elucidated by selectively blocking them. The modified samples were then subjected to laccase and laccase-HBT treatments. On the basis of this data it was possible to establish the role of this mediator. HBT mediates the oxidation of lignin by inducing side-chain oxidation and oxygen-addition products rather than oxidative coupling reactions.}, number={21}, journal={CHEMISTRY-A EUROPEAN JOURNAL}, author={Crestini, C and Jurasek, L and Argyropoulos, DS}, year={2003}, month={Nov}, pages={5371–5378} }
 @article{argyropoulos_2003, title={Salient reactions in lignin during pulping and oxygen bleaching: An overview}, volume={29}, number={9}, journal={Journal of Pulp and Paper Science}, author={Argyropoulos, D. S.}, year={2003}, month={Sep}, pages={308–313} }
 @article{jaaskelainen_sun_argyropoulos_tamminen_hortling_2003, title={The effect of isolation method on the chemical structure of residual lignin}, volume={37}, ISSN={["0043-7719"]}, DOI={10.1007/s00226-003-0163-y}, number={2}, journal={WOOD SCIENCE AND TECHNOLOGY}, author={Jaaskelainen, AS and Sun, Y and Argyropoulos, DS and Tamminen, T and Hortling, B}, year={2003}, month={Oct}, pages={91–102} }
 @article{suchy_argyropoulos_2002, title={Catalysis and activation of oxygen and peroxide delignificaction of chemical pulps: A review}, number={Apr.}, journal={Solutions! (Norcross, Ga.)}, author={Suchy, M. and Argyropoulos, D. S.}, year={2002}, month={Apr}, pages={62} }
 @article{colodette_gomide_girard_jaskelainen_argyropoulos_2002, title={Influence of pulping conditions on eucalyptus kraft pulp yield, quality and bleachability}, number={Mar.}, journal={Solutions! (Norcross, Ga.)}, author={Colodette, J. and Gomide, J. L. and Girard, R. J. and Jaskelainen, A.-S. and Argyropoulos, D. S.}, year={2002}, month={Mar}, pages={62} }
 @article{jurasek_kristofova_sun_argyropoulos_2001, title={Alkaline oxidative degradation of diphenylmethane structures - Activation energy and computational analysis of the reaction mechanism}, volume={79}, ISSN={["0008-4042"]}, DOI={10.1139/cjc-79-9-1394}, number={9}, journal={CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE}, author={Jurasek, L and Kristofova, L and Sun, YJ and Argyropoulos, DS}, year={2001}, month={Sep}, pages={1394–1401} }
 @article{argyropoulos_2001, title={Book Review: Wood and cellulosic chemistry, Second Edition, edited by David N.-S. Hon and Nubuo Shiraishi}, volume={123}, DOI={10.1021/ja015237p}, number={36}, journal={Journal of the American Chemical Society}, author={Argyropoulos, Dimitris}, year={2001}, pages={8880–8881} }
 @article{tohmura_argyropoulos_2001, title={Determination of arylglycerol-beta-aryl ethers and other linkages in lignins using DFRC/P-31 NMR}, volume={49}, ISSN={["0021-8561"]}, DOI={10.1021/jf001026c}, abstractNote={An analytical method for lignins has been developed that involves derivatization followed by reductive cleavage (DFRC), depolymerization, and quantitative (31)P NMR spectroscopy. This technique detects and quantifies the various ether linkages present in softwood residual kraft lignins (RKL) and milled wood lignins (MWL). In addition, the technique supplies new quantitative information about beta-aryl ethers linked to condensed and noncondensed aromatic moieties, including dibenzodioxocins. Within RKL, beta-aryl ether bonds connected to condensed phenolic moieties predominated over those connected to noncondensed phenolic moieties. In addition, the amount of DFRC monomers determined by gas chromatography was minute in the RKL but large in the MWL. This indicates that almost all noncondensed beta-aryl ether linkages were cleaved during kraft pulping. The method offers new avenues for the detailed investigation of the bonding patterns of native and technical lignins.}, number={2}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Tohmura, S and Argyropoulos, DS}, year={2001}, month={Feb}, pages={536–542} }
 @article{akim_colodette_argyropoulos_2001, title={Factors limiting oxygen delignification of kraft pulp}, volume={79}, ISSN={["1480-3291"]}, DOI={10.1139/cjc-79-2-201}, number={2}, journal={CANADIAN JOURNAL OF CHEMISTRY}, author={Akim, LG and Colodette, JL and Argyropoulos, DS}, year={2001}, month={Feb}, pages={201–210} }
 @inbook{crestini_argyropoulos_2001, title={On the role of 1-hydroxybenzotriazole as mediator in the Lacasse oxidation of residual kraft lignin}, volume={785}, ISBN={084123738}, DOI={10.1021/bk-2001-0785.ch023}, abstractNote={In order to elucidate the role of the mediator 1-hydroxybenzotriazole (HBT) in laccase oxidation processes, vanillyl alcohol was oxidized with laccase in the presence and in the absence of this mediator. The pattern of metabolites produced showed that the presence of HBT allowed the formation of oxygen addition products such as o- and p-quinones and aromatic ring cleavage products, while in its absence only oxidative coupling products were observed. Experiments carried out on residual kraft lignin showed the occurrence of coupling reactions during laccase oxidation. In the presence of the laccase-mediator (LM) system the reaction pathway was driven toward side chain oxidation and oxygen addition products, while the formation of condensed structures was depressed, Furthermore, The role of phenolic, aliphatic OH, and COOH moieties in lignin degradation was elucidated by selectively blocking them and then submitting the samples to laccase and laccase-HBT treatments. It was found that the activity of the LM system depends on the presence of phenolic lignin subunits. In actual fact, the reactions carried out on lignins lacking free phenolic groups did not cause any appreciable degradation to the polymer.}, booktitle={Oxidative delignification chemistry: Fundamentals and catalysis}, publisher={Washington, DC: ACS Books}, author={Crestini, C. and Argyropoulos, Dimitris}, year={2001}, pages={373–390} }
 @book{libraries_2001, title={Oxidative delignification chemistry: Fundamentals and catalysis}, volume={785}, ISBN={084123738}, DOI={10.1021/bk-2001-0785}, abstractNote={Oxygen and hydrogen peroxide have always been technologically attractive oxidants to the pulp and paper industry. The fact that molecular oxygen has a triplet ground state whose direct interaction with singlet-state organic molecules is a spin-forbidden transition, limits its oxidative selectivity. Industrially, it would be extremely beneficial to fix molecular oxygen within organic or inorganic compounds capable of transferring it selectively to an organic substrate such as lignin. Since a variety of research endeavours have already been made to catalyse oxygen delignification and activate peroxide delignification of chemical pulps, this paper critically reviews them. In addition, this effort covers peracids, which can be considered as organic molecules containing active oxygen. Dioxiranes have also been shown to possess the ability to transfer a single activated oxygen atom onto aromatic and unsaturated substrates. As such, dimethyldioxirane is reviewed for its potential as a novel and selective bleaching agent for the production of fully-bleached totally chlorine-free (TCF) pulp. Finally, our critical review covers the recent scientific and patent literature which contains a number of examples where transition metals have been used as additives in peroxide and oxygen delignification.}, journal={ACS Symposium Series}, publisher={Washington, DC: ACS Books}, author={Libraries, NC State University}, year={2001} }
 @article{beaton_argyropoulos_2001, title={Photostabilizing milled wood lignin with benzotriazoles and hindered nitroxide}, volume={73}, ISSN={["0031-8655"]}, DOI={10.1562/0031-8655(2001)073<0605:PMWLWB>2.0.CO;2}, abstractNote={The inhibitory processes operating when a 2(-2'-hydroxyphenyl) benzotriazole-based ultraviolet absorber (UVA) and a hindered nitroxide free radical are applied to high-yield pulps were studied using milled wood lignin and filter paper as a model. Using quantitative 31P NMR it was determined that the UVA is almost completely photostable during irradiation, suggesting that its protective mechanism is based primarily on ultraviolet absorption. Furthermore, the nitroxide was found to protect the UVA from photodegradation. Analysis of irradiated lignin samples involved derivatization followed by reductive cleavage of beta-arylether groups. The phenolic-OH groups thus released were quantified using 31P NMR. The benzotriazole/nitroxide stabilizing system was found to cooperatively inhibit the cleavage of beta-arylether groups. Furthermore, this system was found to have a synergistic inhibitory effect on the formation of catechol structures. These results suggest that the synergism observed between benzotriazole-based UV screens and nitroxyl radicals on the inhibition of yellowing could be a result of their ability to slow the formation of catechol structures and beta-O-4 cleavage in addition to the possibility of a UVA-regeneration mechanism.}, number={6}, journal={PHOTOCHEMISTRY AND PHOTOBIOLOGY}, author={Beaton, CR and Argyropoulos, DS}, year={2001}, month={Jun}, pages={605–610} }
 @article{xia_akim_argyropoulos_2001, title={Quantitative C-13 NMR analysis of lignins with internal standards}, volume={49}, ISSN={["1520-5118"]}, DOI={10.1021/jf010333v}, abstractNote={Novel protocols for acquiring quantitative (13)C NMR spectra of lignins have been developed using the internal reference compounds 1,3,5-trioxane and pentafluorobenzene. Trioxane offers a convenient internal standard for collecting inverse gated proton decoupled (13)C NMR spectra for lignins, whereas pentafluorobenzene can be used to provide information on the amount of methine carbon using the DEPT experiment. In each case, the internal reference compounds provide single, un-overlapped sharp signals in the middle of the spectral region, permitting facile integration. These integrals could be used to determine the amounts of different structural features of lignins, expressed in absolute units of millimoles per gram. The optimum parameters for these experiments were validated for a variety of spectrometer platforms, and standard errors were determined for different spectral areas using lignin model compounds and "standard" lignins. In addition, the data derived for the International Round Robin "standard" lignins showed good agreement with the data from quantitative (31)P NMR spectroscopy and published data, obtained by independent laboratories using independent methods of analysis.}, number={8}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Xia, ZC and Akim, LG and Argyropoulos, DS}, year={2001}, month={Aug}, pages={3573–3578} }
 @article{akim_argyropoulos_jouanin_leple_pilate_pollet_lapierre_2001, title={Quantitative P-31 NMR spectroscopy of lignins from transgenic poplars}, volume={55}, ISSN={["0018-3830"]}, DOI={10.1515/HF.2001.064}, abstractNote={Summary Milled wood lignins isolated from genetically modified poplar trees were studied by quantitative 31 P NMR spectroscopy, in combination with thioacidolysis and mild alkaline hydrolysis. The genetic transformation of the trees included down regulation of CAD and COMT enzyme activities. These analyses confirmed that moderate CAD down-regulation does not substantially alter lignin structure. In contrast, severe CAD deficiency alters the lignin structure more profoundly by decreasing the syringyl/guaiacyl ratio and increasing the degree of condensation of the lignin. The most severe alterations were observed in the lignins from the COMT-transformed lines.}, number={4}, journal={HOLZFORSCHUNG}, author={Akim, LG and Argyropoulos, DS and Jouanin, L and Leple, JC and Pilate, G and Pollet, B and Lapierre, C}, year={2001}, pages={386–390} }
 @article{gomide_colodette. j. l._r. c._r._argyropoulos_2000, title={Factors that affect the bleachability of eucalyptus kraft pulp: 2, Influence of pulping parameters}, number={Dec.}, journal={O Papel}, author={Gomide, J. L. and Colodette. J. L., Oliveira and R. C., Girard and R. and Argyropoulos, D. S.}, year={2000}, month={Dec}, pages={61–70} }
 @article{argyropoulos_halevy_peng_2000, title={Photoyellowing inhibition of bleached high yield pulps using novel water-soluble UV screens}, volume={7}, DOI={10.1562/0031-8655(2000)0710141piobhy2.0.co2}, abstractNote={To address the deficiencies of benzophenone UV screens for preventing brightness reversion in high yield mechanical papers, we synthesized a new series of such materials with enhanced water solubility and compatibility with the lignocellulosic substrate. A series of 2,4-dihydroxybenzophenones (DHB) were synthesized containing various Mannich bases at the C3 position of one of its rings. They possess the UV-screening ability of o-hydroxylbenzophenones, and they also contain tertiary nitrogen atoms that may function as radical scavengers. Aqueous solutions of the hydrochloride salt of 3-(dimethylaminomethylene)-2,4-dihydroxylbenzophenone (1), when applied on bleached chemithermomechanical pulp (CTMP) sheets, were significantly more efficient in preventing photoyellowing than the original DHB applied on the sheets from ethanol–water solutions. This confirmed our original hypothesis that increasing the compatibility of the UV screen with the lignocellulosic matrix would increase its efficiency in preventing photoyellowing. Compound 1, however, was found to be somewhat more effective than its hydrochloride salt toward preventing photoyellowing. This was attributed to the synergistic action of the free tertiary aminic center attached on the molecule with its UV-screening ability. To comprehend further the various parameters that influence the photoyellowing inhibition performance of these compounds and DHB with bleached CTMP pulp fibers, a series of handsheets were prepared at different pH. The interactions of the protonated compound 1 with pulp fibers were then evaluated by studying their kinetics of absorption and desorption to and from the fiber matrix. This part of our study found that the adsorption of protonated Mannich derivatives of DHB onto pulp is most likely governed by a cation-exchange mechanism involving the cationic amine group with the sulfonic and carboxylic acid groups located on the surface of the fibers. The pH the paper sheet was made from was also found to affect profoundly the adsorption and retention characteristics of these compounds onto the lignocellulosic matrix.}, number={2}, journal={Photochemistry and Photobiology}, author={Argyropoulos, Dimitris and Halevy, P. and Peng, P.}, year={2000}, pages={141–148} }
 @article{ahvazi_argyropoulos_2000, title={Proton spin-lattice relaxation time measurements of solid wood and its constituents as a function of pH, Part I}, volume={34}, DOI={10.1007/s002260050007}, journal={Wood Science and Technology}, author={Ahvazi, B. and Argyropoulos, Dimitris}, year={2000}, pages={45–53} }
 @inbook{liu_carriero_pye_argyropoulos_1999, title={A comparison of the structural changes occurring in lignin during alcell and kraft pulping of hardwoods and softwoods}, volume={742}, ISBN={0841236119}, DOI={10.1021/bk-2000-0742.ch022}, abstractNote={During this investigation, softwood and hardwood chips were pulped to different extents using conventional kraft and Alcell protocols. The dissolved and residual lignins were then isolated and their functional group distributions examined using quantitative 31P NMR. For both wood species, the solubilized kraft lignins contained the highest abundance of phenolic hydroxyl groups at all degrees of delignification, while the residual kraft lignins contained the lowest. This may be related to the considerably greater solvating abilities of alkaline aqueous media as opposed to those of ethanol toward inducing solubilization of the phenolic moieties. Consequently, at a given degree of delignification, a greater proportion of phenolic units are retained in the Alcell pulps, contributing to their documented higher reactivity with oxygen. As far as residual lignins are concerned, the data showed that condensed phenolic units are formed in greater abundance within softwood than in hardwood pulps for both processes. More specifically, condensed}, booktitle={Lignin: Historical, biological and materials perspectives}, publisher={Washington, DC: ACS Books}, author={Liu, Y. and Carriero, S. and Pye, K. and Argyropoulos, Dimitris}, editor={W. G. Glasser, R. A. Northey and Schultz, T. P.Editors}, year={1999}, pages={447–464} }
 @article{moore_argyropoulos_1999, title={Determination of peroxygen species present in pulp fiber matrixes}, volume={71}, ISSN={["1520-6882"]}, DOI={10.1021/ac980500z}, abstractNote={A new chromatographic method for the determination of oxidants, such as peroxyborates and peroxides, present in a pulp matrix has been developed. The new method is characterized by its high reproducibility, its low limit of detection, and its high selectivity. Thioanisole (methylphenyl sulfide) is shown to selectively and quantitatively react with oxidants that are present within a pulp matrix. The experimental protocol proposed requires an HPLC system with a normal-phase column. The method allows for the quantitative monitoring of the thioanisole starting material, as well as the products of oxidation, methylphenyl sulfoxide and methylphenyl sulfone. After a 2-day reaction period, the analysis time for a sample is less than 20 min. The detection limit is 2.7 × 10-6 M for the sulfoxide and sulfone and less than 5.0 × 10-7 M for the thioanisole. This novel approach for monitoring oxidants present on solid lignocellulosic matrixes may provide pulp and paper manufacturers with a new tool for the study of the long-term bleaching effectiveness of peroxy-containing chemical additives.}, number={1}, journal={ANALYTICAL CHEMISTRY}, author={Moore, DA and Argyropoulos, DS}, year={1999}, month={Jan}, pages={109–114} }
 @article{ahvazi_crestini_argyropoulos_1999, title={F-19 nuclear magnetic resonance spectroscopy for the quantitative detection and classification of carbonyl groups in lignins}, volume={47}, ISSN={["1520-5118"]}, DOI={10.1021/jf980431p}, abstractNote={A novel method that permits the quantitative detection and classification of various carbonyl groups in lignins has been developed. The proposed method was optimized with the quantitative trifluoromethylation of a series of carbonyl-containing lignin-like model compounds. This effort was followed by (19)F NMR spectral analyses of the resulting fluorine derivatives allowing for a thorough understanding of their structure/(19)F chemical shift relationships. The various carbonyl groups present in lignins were also investigated by trifluoromethylating them in the presence of catalytic amounts of tetramethylammonium fluoride (TMAF), followed by hydrolysis with TMAF in tetrahydrofuran. By using a variety of selective reactions, it became possible to assign a number of prominent (19)F NMR signals to a variety of carbonyl groups present in lignins. These studies demonstrated that the proposed method can be applied to the quantitative determination of carbonyl groups that are present in soluble native and technical lignins.}, number={1}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Ahvazi, BC and Crestini, C and Argyropoulos, DS}, year={1999}, month={Jan}, pages={190–201} }
 @article{ahvazi_argyropoulos_1999, title={Proton spin-lattice relaxation time measurements of solid wood and its constituents as a function of pH: Part II}, volume={15}, ISSN={["0926-2040"]}, DOI={10.1016/S0926-2040(99)00046-6}, abstractNote={The proton spin-lattice relaxation times (T1H) for isolated cuoxam lignin and fully bleached cellulose were measured as a function of pH in the solid-state. These experiments provided the opportunity to examine for possible macromolecular connectivities that may be present between lignin and carbohydrates within softwood. These studies have shown that the molecular mobilities of the isolated polymeric constituents of wood are affected by the ionization of their functional groups at different pHs. The shapes of the plots of T1H as a function of pH for the two isolated polymers were dramatically different, while those for softwood were similar. This fact provides evidence supporting the notion that in wood, lignin and carbohydrates are intimately associated with each other.}, number={1}, journal={SOLID STATE NUCLEAR MAGNETIC RESONANCE}, author={Ahvazi, BC and Argyropoulos, DS}, year={1999}, month={Oct}, pages={49–57} }
 @article{sun_fenster_yu_berry_argyropoulos_1999, title={The effect of metal ions on the reaction of hydrogen peroxide with Kraft lignin model compounds}, volume={77}, ISSN={["0008-4042"]}, DOI={10.1139/cjc-77-5-6-667}, abstractNote={Peroxide bleaching is significantly affected by transition and alkaline earth metals. Isolating the effects of different transition and alkaline earth metals on the reactions of peroxide with different representative lignin structures allows the separation of the positive from the negative contributions of these metal ions. In this work, five monomeric or dimeric phenolic lignin model compounds were treated with alkaline hydrogen peroxide in the absence or presence of Mn2+, Cu2+, Fe3+, and Mg2+. We followed the disappearance of the starting material and the progress of demethylation, radical coupling and oxalic acid formation were followed. Transition metals increased the reactivities of all the lignin model compounds with hydrogen peroxide in the order Mn2+ > Cu2+ > Fe3+, which is the same as the order of activity toward peroxide decomposition while Mg2+ stabilized the system. Demethylation, radical coupling, and oxalic acid formation were all increased by the presence of transition metals in the system and decreased by the addition of Mg2+. The acceleration of the total degree of reaction and of the demethoxylation reactions improves peroxide bleaching, but the increase in the radical coupling reactions can affect the further bleachability of pulp while the increase in the formation of oxalic acid could lead to a greater probability of scaling.Key words: lignins, hydrogen peroxide, peroxide bleaching, reactivity, chemical pulps, metal compounds, alkali treatment, transition metals, delignification.}, number={5-6}, journal={CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE}, author={Sun, Y and Fenster, M and Yu, A and Berry, RM and Argyropoulos, DS}, year={1999}, pages={667–675} }
 @article{jiang_argyropoulos_1998, title={Coupling P-31 NMR with the Mannich reaction for the quantitative analysis of lignin}, volume={76}, ISSN={["0008-4042"]}, DOI={10.1139/cjc-76-5-612}, abstractNote={The reactivity of lignin model compounds under Mannich conditions with piperidine and formaldehyde was studied. The piperidinomethyl group was confirmed to be introduced quantitatively at sterically unhindered positions ortho to a phenolic hydroxyl when the substrate was allowed to react under ambient conditions. The sequential application of the Mannich reaction followed by quantitative 31 P NMR on a variety of lignin samples allowed the amounts of various aromatic groups bearing free phenolic hydroxyls to be determined. More specifically, the technique allowed the quantification of para-hydroxyl phenols, catechols, guaiacols, and phenols bearing C5 or C6 substituents. The quantitative reliability of the technique was also examined with a series of dissolved kraft lignins, isolated at various degrees of delignification. The data were found to favourably compare to those obtained by permanganate oxidation.}, number={5}, journal={CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE}, author={Jiang, ZH and Argyropoulos, DS}, year={1998}, month={May}, pages={612–622} }
 @article{asgari_argyropoulos_1998, title={Fundamentals of oxygen delignification. Part II. Functional group formation elimination in residual kraft lignin}, volume={76}, ISSN={["0008-4042"]}, DOI={10.1139/cjc-76-11-1606}, abstractNote={The complex interaction of softwood residual kraft lignin with oxygen at elevated temperatures, pressures, and pH's was investigated by isolating and systematically oxidizing the lignin, as a function of time and temperature. The isolation of the oxidized lignin was carried out using a multistep procedure developed specifically to recover all species. Detailed quantitative 31 P NMR measurements provided, for the first time, three-dimensional plots describing the formation and (or) elimination of the various functional groups. Oxidative demethoxylation reactions were found to induce the formation of catechols, which are, most likely, reactive intermediates of the oxidation. The rate of carboxylic acid formation and guaiacyl phenol elimination was found to follow two distinct phases: a rapid initial phase followed by a slower phase. More specifically, the rate of carboxylic acid group formation was found to dramatically increase as the reaction temperature increased, analogous to the profiles obtained for the elimination of guaiacyl phenolic units. At reaction temperatures typical of conventional commercial oxygen delignification installations (80-100°C), only minor oxidation was found to occur within the lignin. At these temperatures, increasing the reaction time did not significantly aid the formation of carboxylic acid groups on lignin despite the idealized two- phase homogeneous conditions. The technological ramifications of these data imply that a three-phase oxygen delignification system, operating at temperatures below 100°C, causes only minor oxidative changes to the structure of the lignin in the fibre. It was also possible to isolate the effect of alkali and temperature on the structure of residual kraft lignin through experiments in which pressurized oxygen was replaced by nitrogen. These data revealed a concealed set of alkali-induced condensation and fragmentation reactions.}, number={11}, journal={CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE}, author={Asgari, F and Argyropoulos, DS}, year={1998}, month={Nov}, pages={1606–1615} }
 @article{bouchard_maine_argyropoulos_berry_1998, title={Kraft pulp bleaching using in-situ dimethyldioxirane: Mechanism and reactivity of the oxidants}, volume={52}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1998.52.5.499}, abstractNote={Dimethyldioxirane (DMD) is a cyclic peroxide made by oxidizing acetone with the peroxymonosulfate (PMS) anion in water buffered at pH 7.5 using sodium bicarbonate. It has been shown that DMD generation can be achieved in-situ within a pulp suspension allowing very selective TCF bleaching of kraft pulp. This process involves simultaneous generation of DMD, reaction of PMS and DMD with residual lignin, and spontaneous decomposition of both oxidants. In this work, we have studied the effect of pH and the nature of the buffering agent on the efficiency of delignification of kraft pulp. We have found a positive linear relationship between delignification and pH in the range from 2 to 11 when using buffers other than bicarbonate. However, using bicarbonate gives a significant enhancement of delignification between pH 7 and 8. From this work, we have proposed that the H 2 CO 3 /HCO 3 - buffer improves the rate of DMD formation during DMD in-situ bleaching and possibly during DMD synthesis. A possible mechanism accounting for this improvement is proposed.}, number={5}, journal={HOLZFORSCHUNG}, author={Bouchard, J and Maine, C and Argyropoulos, DS and Berry, RM}, year={1998}, pages={499–505} }
 @inbook{argyropoulos_menachem._1998, title={Lignin}, ISBN={354063567X}, DOI={10.1007/978-3-662-03680-8_12}, booktitle={Biopolymers from renewable resources}, publisher={Berlin: Springer}, author={Argyropoulos, Dimitris and Menachem., S. B.}, year={1998}, pages={292–322} }
 @article{liu_argyropoulos_1998, title={Maintaining the brightness of mechanical pulps with solid-state perborate bleaching}, volume={52}, ISSN={["1437-434X"]}, DOI={10.1515/hfsg.1998.52.3.319}, abstractNote={Since vicinal diols present in carbohydrates may form perborate esters with hydrogen peroxide and borax, such species were loaded onto peroxide bleached and unhleached mechanical pulps. These species were shown to act as slow solid-state oxidizing bleaching agents capahle of partially restoring, in the dark, the brightness losses induced on mechanical pulps during direct outdoor and indoor irradiation. More specifically, bleached TMP handsheets were impregnated at pH 9.5 with a mixture comprised of 2 % borax and 1% hydrogen peroxide. These samples were then irradiated with indoor direct sunlight for 5 hours followed by a dark bleaching period of ahout 7 hours. At the end of this period brightness readings were recorded and the cycle was repeated. thus simulating indoor handling of paper products. For a 33 hour of cumulative direct indoor sunlight irradiation, the percentage stabilization offered was about 70%. When a similar solution was used to impregnate unbleached TMP samples, a brightness gain of about 10 ISO points was obtained without using any heat for the bleaching stage. While repeated irradiation and dark storage cycles, over a cumulative period of 37 hours, resulted in approximately 3 points of brightness losses the initial brightness gains due to bleaching were maintained. The application of perborates possibly offers a potential solution to thermal reversion issues that face most mechanical pulp mills.}, number={3}, journal={HOLZFORSCHUNG}, author={Liu, ZQ and Argyropoulos, DS}, year={1998}, pages={319–324} }
 @article{ahvazi_pageau_argyropoulos_1998, title={On the formation of diphenylmethane structures in lignin under kraft, EMCC (R), and soda pulping conditions}, volume={76}, ISSN={["1480-3291"]}, DOI={10.1139/cjc-76-5-506}, number={5}, journal={CANADIAN JOURNAL OF CHEMISTRY}, author={Ahvazi, BC and Pageau, G and Argyropoulos, DS}, year={1998}, month={May}, pages={506–512} }
 @article{argyropoulos_zhang_1998, title={Semiquantitative determination of quinonoid structures in isolated lignins by P-31 nuclear magnetic resonance}, volume={46}, ISSN={["1520-5118"]}, DOI={10.1021/jf9804802}, abstractNote={A semiquantitative analytical method has been developed for the determination of the total quinonoid content (o-benzoquinones and p-benzoquinones) of soluble lignins. The method is based on detailed measurements and observations made with model o- and p-quinones, which in dry organic solvents were shown to form adducts with trimethyl phosphite in quantitative yield. These adducts gave 31P NMR signals for o- and p-quinones at around −46 and −2 ppm, respectively. In the presence of moisture and lignin the adducts from o-quinones were shown to be hydrolyzed to the open ring product, dimethylphenyl phosphate (−2 ppm), at an overall yield of ∼70%. Similarly, the hydrolysis yields of p-quinone adducts with trimethyl phosphite were ∼70%. Consequently, a number of important issues in relation to the use of trimethyl phosphite toward the quantitative analysis of quinonoid groups in lignins have been investigated, which permitted the development of an experimental semiquantitative protocol recommended for spectral acquisition. Keywords: Adducts; analysis; determination; lignins; nuclear magnetic resonance (NMR); phosphorus; quinones; spectroscopy}, number={11}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Argyropoulos, DS and Zhang, LM}, year={1998}, month={Nov}, pages={4628–4634} }
 @article{crestini_sermanni_argyropoulos_1998, title={Structural modifications induced during biodegradation of wheat lignin by Lentinula edodes}, volume={6}, ISSN={["1464-3391"]}, DOI={10.1016/S0968-0896(98)00047-9}, abstractNote={The structural modifications occurring during wheat straw lignin biodegradation were evaluated by the concerted use of 31P-, 1H- and 2D homo- and heteronuclear NMR spectroscopies. Straw lignin was found to be oxidatively degraded via stereoselective side-chain oxidation as evidenced by a lower erythro/threo ratio. Significantly lower amounts of phenolic hydroxy and methoxy groups in the decayed lignin may be indicative that its structure after the fungal treatment contained a lower amount of aromatic units. In addition an increase in carboxylic acids content, that cannot be explained only on the basis of side-chain oxidation reactions, was also apparent. This evidence, coupled with pertinent data collected during this effort, suggests the occurrence of aromatic ring cleavage reactions. In fact the oxidative degradation of lignin model compounds by fungi has been reported to occur via the 3-oxoadipate pathway which is known to cause aromatic ring cleavage with the formation of aliphatic chains. The presence of aliphatic moieties in the decayed lignin was confirmed by detailed 1H- and 2D NMR spectroscopic analyses.}, number={7}, journal={BIOORGANIC & MEDICINAL CHEMISTRY}, author={Crestini, C and Sermanni, GG and Argyropoulos, DS}, year={1998}, month={Jul}, pages={967–973} }
 @article{crestini_argyropoulos_1998, title={The early oxidative biodegradation steps of residual kraft lignin models with laccase}, volume={6}, ISSN={["1464-3391"]}, DOI={10.1016/s0968-0896(98)00173-4}, abstractNote={A number of model compounds resembling the fundamental bonding patterns of residual kraft lignin, including a series of stilbenes, were incubated with laccase from Trametes versicolor in the presence and absence of delignification ‘mediators’ ABTS and HBT. The condensed kraft lignin model compounds seem to undergo initial degradation by laccase mainly via benzylic oxidation, demethylation and hydroxylation reactions. Phenolic 5-5′, diphenylmethane and α-5 lignin models were found to be degraded mainly via side-chain oxidation reactions. Among the models studied, a phenolic stilbene was found to be the most reactive, yielding several products showing side-chain oxidation/transposition, demethoxylation and hydroxylation reactions. Non-phenolic 5-5′, diphenylmethane and stilbene model compounds were found unreactive even in the presence of the laccase-mediator system.}, number={11}, journal={BIOORGANIC & MEDICINAL CHEMISTRY}, author={Crestini, C and Argyropoulos, DS}, year={1998}, month={Nov}, pages={2161–2169} }
 @article{spyros_argyropoulos_marchessault_1997, title={A study of poly(hydroxyalkanoate)s by quantitative P-31 NMR spectroscopy: Molecular weight and chain cleavage}, volume={30}, ISSN={["0024-9297"]}, DOI={10.1021/ma9601979}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTA Study of Poly(hydroxyalkanoate)s by Quantitative 31P NMR Spectroscopy: Molecular Weight and Chain CleavageA. Spyros, D. S. Argyropoulos, and R. H. MarchessaultView Author Information Department of Chemistry and Pulp and Paper Research Centre, McGill University, 3420 University Street, Montreal, Quebec H3A 2A7, Canada Cite this: Macromolecules 1997, 30, 2, 327–329Publication Date (Web):January 27, 1997Publication History Received7 February 1996Revised12 August 1996Published online27 January 1997Published inissue 1 January 1997https://doi.org/10.1021/ma9601979Copyright © 1997 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views763Altmetric-Citations41LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (125 KB) Get e-AlertsSUBJECTS:Biopolymers,Gel permeation chromatography,Nuclear magnetic resonance spectroscopy,Plastics,Polymers Get e-Alerts}, number={2}, journal={MACROMOLECULES}, author={Spyros, A and Argyropoulos, DS and Marchessault, RH}, year={1997}, month={Jan}, pages={327–329} }
 @inbook{argyropoulos_menachem_1997, title={Lignin}, volume={57}, DOI={10.1007/bfb0102073}, booktitle={Advances in Biochemical Engineering/biotechnology}, author={Argyropoulos, Dimitris and Menachem, S. B.}, year={1997}, pages={127–158} }
 @article{crestini_argyropoulos_1997, title={Structural analysis of wheat straw lignin by quantitative P-31 and 2D NMR spectroscopy. The occurrence of ester bonds and alpha-O-4 substructures}, volume={45}, ISSN={["1520-5118"]}, DOI={10.1021/jf960568k}, abstractNote={By combining mild alkaline hydrolysis with quantitative 31P NMR we have been able to arrive at a protocol for determining the various ester linkages and their relative contributions to the overall structure of wheat straw lignin. Additional information on the identity and location of these bonds was sought by the application of GC/MS and two-dimensional 13C−1H heterocorrelation NMR experiments. Milled straw lignin was found to contain about 12 ester units per 100 phenylpropane units. Approximately 77% of the carboxyl fraction of these ester bonds was found to be composed of p-coumaric acid while the rest was other aromatic acids bound to lignin via intra- and/or intermolecular ester bonds. In contrast, the hydroxyl fraction of the ester bonds was found to be almost exclusively aliphatic. A small fraction (about 1.6%) of the milled straw lignin units was found to be esterified through the phenolic hydroxyl groups of C-5 condensed phenolic units. The application of 13C−1H correlative NMR experiments revealed that acylation occurs only at the γ-position of the lignin side chain. Detailed studies of two-dimensional HOHAHA and HMQC experiments failed to show evidence for the presence of α-O-4 substructures in milled wheat straw lignin. Keywords: Wheat straw lignin; 2D NMR; structural analysis}, number={4}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Crestini, C and Argyropoulos, DS}, year={1997}, month={Apr}, pages={1212–1219} }
 @article{ahvazi_argyropoulos_1997, title={Thermodynamic parameters governing the stereoselective degradation of arylglycerol-?-aryl ether bonds in milled wood lignin under kraft pulping conditions}, volume={12}, DOI={10.3183/npprj-1997-12-04-p282-288}, abstractNote={Abstract During this investigation, softwood (picea mariana) milled wood lignin was subjected to kraft pulping conditions at the temperature range 100-160 o C, for variable lengths of time. After quantitative isolation of the treated lignins, they were subjected to 31 PNMR analyses which allowed the absolute rates of scission of the erythro and thewo diastereomers of the arylglycerol-B-aryl ether structures present in lignin to be derived.The plots of the kinetic data revealed that two kinetic regimes operate i.e. an initial fast phase that is followed by another slower phase. In agreement with previous accounts, the rate constants for these scission reactions were found to follow a pseudo-first-order rate law, during both phases. Rate constant data obtained during this effort, invariably indicated that the erythro isomers of the R-0-4 units of softwood milled wood lignin cleave faster than their thr-eo counterparts during both phases. At elevated temperatures (160 "C) the difference was found to be augmented. The general stability of the threo diastereomers toward kraft pulping seems to be the manifestation of a considerably slower reaction of the pulping reagents with the threo diastereomers of the B-aryl ethers. Arrhenius and Eyring plots o i these data supplied the complete profile of thermodynamic parameters governing this commercially important ether scission reaction.}, number={4}, journal={Nordic Pulp & Paper Research Journal}, author={Ahvazi, B. and Argyropoulos, Dimitris}, year={1997}, pages={282–288} }
 @article{sun_argyropoulos_1996, title={A comparison of the reactivity and efficiency of ozone, chlorine dioxide, dimethyldioxirane and hydrogen peroxide with residual kraft lignin}, volume={50}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1996.50.2.175}, abstractNote={Residual lignin isolated from a conventional softwood (Picea mariana) kraft pulp was reacted in homogeneous solutions with varying charges of ozone, chlorine dioxide, dimethyldioxirane (DMD) and alkaline hydrogen peroxide, followed by quantitative 31 P NMR analyses of their functional groups. This effort supplied plots of relative reactivity of these reagents toward specific functional groups present in lignin, and it revealed salient features that control their reactivity and efficiency. The guaiacyl phenolic units, present on the lignin, were found to be the major sites of attack for all the surveyed oxidative treatments. At a given charge, ozone and chlorine dioxide were found to be most efficient in causing the formation of carboxylic acids on residual kraft lignin. Alternatively, low charges of ozone and DMD may act as activating stages prior to another bleaching stage i.e chlorine dioxide and/or alkaline hydrogen peroxide, since they were found to introduce free phenolic hydroxyl groups in residual lignin. Most of the condensed phenolic units present in residual kraft lignin react with the bleaching reagents surveyed. However, it is likely that certain condensed structures are resistant to attack. At high charges of alkaline hydrogen peroxide the extent of condensed phenolic unit elimination was similar to those observed for chlorine dioxide and ozone.}, number={2}, journal={HOLZFORSCHUNG}, author={Sun, YJ and Argyropoulos, DS}, year={1996}, pages={175–182} }
 @article{ahwazi_crestini_argyropoulos_1996, title={F-19 nuclear magnetic resonance spectroscopy for the elucidation of carbonyl groups in lignins .1. Model compounds}, volume={44}, ISSN={["1520-5118"]}, DOI={10.1021/jf960154r}, abstractNote={A new method for the detection of different classes of carbonyl groups in a series of carbonyl-containing lignin-like model compounds has been developed. The method is based on the selective fluoride-induced trifluoromethylation of carbonyl groups with (trifluoromethyl)trimethylsilane (TMS-CF3) in the presence of tetramethylammonium fluoride (TMAF), followed by hydrolysis with aqueous HF or TMAF in the case of quinones. In this study a series of ketones, aldehydes, quinones, and dimeric-lignin model compounds were quantitatively trifluoromethylated followed by 19F NMR spectral analyses of the resulting fluorine-containing derivatives, allowing for a thorough understanding of their structure/19F chemical shift relationships. These studies have shown that the 19F-NMR chemical shifts of the trifluoromethyl groups vary significantly and consistently for various classes of carbonyl groups which may be present in complex lignocellulosic materials. These studies are to form the basis for the development of a novel and sensitive method that can be used to obtain quantitative information on the various carbonyl groups present in such materials. Keywords: Carbonyl groups; model compounds; Ruppert's reagent; trifluoromethylation; nuclear magnetic resonance (NMR); chemical shifts}, number={8}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Ahwazi, B. and Crestini, C. and Argyropoulos, Dimitris}, year={1996}, month={Aug}, pages={2167–2175} }
 @article{bouchard_maine_berry_argyropoulos_1996, title={Kraft pulp bleaching using dimethyldioxirane: Stability of the oxidants}, volume={74}, ISSN={["0008-4042"]}, DOI={10.1139/v96-026}, abstractNote={Dimethyldioxirane (DMD) is a cyclic peroxide made by oxidizing acetone with peroxymonosulfate (PMS) in water buffered at pH 7.5 using sodium bicarbonate. It has been shown that DMD generation can be achieved in situ within a pulp suspension allowing very selective TCF bleaching of kraft pulp. This process involves simultaneous generation of DMD, reaction of PMS and DMD with residual lignin, and spontaneous decomposition of both oxidants. The first part of this work is a kinetics study of the decomposition of PMS and DMD as a function of pH under conditions similar to those for in situ bleaching. The effect of chelation as well as the effect of transition metal ions on decomposition rate was also investigated. DMD is very sensitive to pH and its half-life is very short under alkaline conditions. The presence of any transition metal ion that can be involved in a one-electron transfer is detrimental to DMD stability. However, fast reaction of DMD with pulp almost counteracts the effect of metal ions. Key words: bleaching, peroxymonosulphate, dimethyldioxirane, metal ions, kinetics, decomposition, kraft pulp.}, number={2}, journal={CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE}, author={Bouchard, J and Maine, C and Berry, RM and Argyropoulos, DS}, year={1996}, month={Feb}, pages={232–237} }
 @article{argyropoulos_sun_1996, title={Photochemically induced solid-state degradation, condensation, and rearrangement reactions in lignin model compounds and milled wood lignin}, volume={64}, ISSN={["0031-8655"]}, DOI={10.1111/j.1751-1097.1996.tb03098.x}, abstractNote={— Milled wood lignin produced from alkaline hydrogen peroxide-bleached softwood thermomechanical pulp (TMP) fibers was adsorbed on pure cellulose and irradiated for variable periods of time under oxygen and/or nitrogen. The absolute amounts of β-O-4 ethers, phenolic hydroxyl groups, carboxylic acids and various condensed phenolic units were quantified, nondestructively, using 31P NMR spectroscopy. Photoirradiation was found to severely cleave the β-O-4 ethers present in lignin with the concomitant formation of new phenolic units. The rate of this cleavage was found to be faster under oxygen than under nitrogen. The catalytic role of oxygen can be rationalized by invoking the formation of peroxy free radicals that may initiate new sites of radical generation (e.g. ketyl radicals) within the lignin causing the subsequent breakdown of the β-O-4 linkage. The photoirradiation was found to cause a net increase of the C5-related condensed phenolic units in lignin. Among these, Cα-C5 and/ or Cβ-C5 phenolic moieties were found to predominate. Similar irradiation of a binary mixture of model compounds resembling structures present in softwood lignin resulted in 18 products that were identified and quantified using gas chromatography coupled to mass spectrometry. The photochemical products obtained supported the phenacyl and ketyl mechanistic pathways to pho-toyellowing, whereas the detection of β-5 coupling products (common in both the model compound and milled wood lignin studies) may point a new avenue toward the formation of light-induced products that has not been previously considered in the solid state.}, number={3}, journal={PHOTOCHEMISTRY AND PHOTOBIOLOGY}, author={Argyropoulos, DS and Sun, YJ}, year={1996}, month={Sep}, pages={510–517} }
 @article{ahvazi_argyropoulos_1996, title={Quantitative trifluoromethylation of carbonyl-containing lignin model compounds}, volume={78}, ISSN={["0022-1139"]}, DOI={10.1016/0022-1139(96)03431-8}, abstractNote={The efficient trifluoromethylation of a series of carbonyl-containing lignin model compounds was made possible by using Ruppert' s reagent in the presence of tetramethylammonium fluoride (TMAF), followed by hydrolysis with aqueous HF. These studies demonstrate that such a method can quantitatively convert carbonyl groups to the CF3-containing compounds, thus qualifying the procedure as a potential analytical tool for the determination of carbonyl groups in lignins.}, number={2}, journal={JOURNAL OF FLUORINE CHEMISTRY}, author={Ahvazi, BC and Argyropoulos, DS}, year={1996}, month={Jun}, pages={195–198} }
 @article{granata_argyropoulos_1995, title={2-CHLORO-4,4,5,5-TETRAMETHYL-1,3,2-DIOXAPHOSPHOLANE, A REAGENT FOR THE ACCURATE DETERMINATION OF THE UNCONDENSED AND CONDENSED PHENOLIC MOIETIES IN LIGNINS}, volume={43}, ISSN={["0021-8561"]}, DOI={10.1021/jf00054a023}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT2-Chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane, a Reagent for the Accurate Determination of the Uncondensed and Condensed Phenolic Moieties in LigninsAlessandro Granata and Dimitris S. ArgyropoulosCite this: J. Agric. Food Chem. 1995, 43, 6, 1538–1544Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June 1995https://doi.org/10.1021/jf00054a023RIGHTS & PERMISSIONSArticle Views2701Altmetric-Citations614LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (740 KB) Get e-Alerts Get e-Alerts}, number={6}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={GRANATA, A and ARGYROPOULOS, DS}, year={1995}, month={Jun}, pages={1538–1544} }
 @article{jiang_argyropoulos_granata_1995, title={CORRELATION-ANALYSIS OF P-31 NMR CHEMICAL-SHIFTS WITH SUBSTITUENT EFFECTS OF PHENOLS}, volume={33}, ISSN={["0749-1581"]}, DOI={10.1002/mrc.1260330509}, abstractNote={Over 60 lignin-related model compounds were phosphitylated with 2-chloro-4,4,5,5-tetramethyldioxaphospholane, a sterically hindered analogue of 2-chloro-1,3,2-dioxaphospholane used in earlier work, and their 31P chemical shifts were recorded. Excellent resolution between the chemical shifts of phosphitylated carboxylic acids, phenols and aliphatic alcohols was obtained. The correlations of the phosphorus chemical shifts with the chemical environments of lignin-related phenols using the Hammett principles provided an excellent linear relationship between the resonance substituent constant, σ, and the corresponding 31P NMR chemical shift values for para-substituted lignin-related phenols. In addition, a correlation between 31P NMR chemical shifts for ortho- and para-substituted phosphitylated phenols was obtained. A set of empirical parameters that permits the accurate prediction of 31P NMR chemical shifts of lignin-related phenolic compounds derivatized with 2-chloro-4,4,5,5-tetramethyldioxaphospholane was thus obtained.}, number={5}, journal={MAGNETIC RESONANCE IN CHEMISTRY}, author={JIANG, ZH and ARGYROPOULOS, DS and GRANATA, A}, year={1995}, month={May}, pages={375–382} }
 @article{argyropoulos_morin_lapcik_1995, title={MAGNETIC-FIELD AND TEMPERATURE EFFECTS ON THE SOLID-STATE PROTON SPIN-LATTICE RELAXATION-TIME MEASUREMENTS OF WOOD AND PULPS}, volume={49}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1995.49.2.115}, abstractNote={The proton spin-lattice relaxation times (T 1 ) for a series of progressively sulphonated black spruce pulps were measured at two static magnetic fields and at a variety of temperatures. These determinations showed that the frequency of the anisotropic molecular motions of carbohydrates and lignin responsible for spin relaxation on wood and pulps is of the order of 10 -9 s. For cross-polarization measurements with a 300 MHz solid state NMR spectrometer, room temperature seems to be close to the T 1 versus correlation time minimum}, number={2}, journal={HOLZFORSCHUNG}, author={ARGYROPOULOS, DS and MORIN, FG and LAPCIK, L}, year={1995}, pages={115–118} }
 @misc{argyropoulos_heitner_schmidt_1995, title={OBSERVATION OF QUINONOID GROUPS DURING THE LIGHT-INDUCED YELLOWING OF SOFTWOOD MECHANICAL PULP}, volume={21}, ISSN={["0922-6168"]}, DOI={10.1007/BF03052257}, number={3-5}, journal={RESEARCH ON CHEMICAL INTERMEDIATES}, author={ARGYROPOULOS, DS and HEITNER, C and SCHMIDT, JA}, year={1995}, pages={263–274} }
 @misc{argyropoulos_1995, title={P-31 NMR IN WOOD CHEMISTRY - A REVIEW OF RECENT PROGRESS}, volume={21}, ISSN={["0922-6168"]}, DOI={10.1007/BF03052265}, number={3-5}, journal={RESEARCH ON CHEMICAL INTERMEDIATES}, author={ARGYROPOULOS, DS}, year={1995}, pages={373–395} }
 @article{argyropoulos_morin_1995, title={Probing the macromolecular structure of wood and pulps with proton spin-lattice relaxation time measurements in the solid state}, volume={29}, DOI={10.1007/bf00196929}, number={1}, journal={Wood Science and Technology}, author={Argyropoulos, Dimitris and Morin, F.}, year={1995}, pages={19–30} }
 @article{faix_argyropoulos_robert_neirinck_1994, title={DETERMINATION OF HYDROXYL-GROUPS IN LIGNINS EVALUATION OF H-1-NMR, C-13-NMR, P-31-NMR, FTIR AND WET CHEMICAL METHODS}, volume={48}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1994.48.5.387}, number={5}, journal={HOLZFORSCHUNG}, author={FAIX, O and ARGYROPOULOS, DS and ROBERT, D and NEIRINCK, V}, year={1994}, pages={387–394} }
 @article{chan_argyropoulos_white_yeager_hay_1994, title={FACILE QUANTITATIVE-ANALYSIS OF HYDROXYL END-GROUPS OF POLY(2,6-DIMETHYL-1,4-PHENYLENE OXIDE)S BY P-31 NMR-SPECTROSCOPY}, volume={27}, ISSN={["0024-9297"]}, DOI={10.1021/ma00100a021}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFacile Quantitative Analysis of Hydroxyl End Groups of Poly(2,6-dimethyl-1,4-phenylene oxide)s by 31P NMR SpectroscopyK. P. Chan, D. S. Argyropoulos, D. M. White, G. W. Yeager, and A. S. HayCite this: Macromolecules 1994, 27, 22, 6371–6375Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October 1994https://doi.org/10.1021/ma00100a021RIGHTS & PERMISSIONSArticle Views357Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (526 KB) Get e-Alertsclose Get e-Alerts}, number={22}, journal={MACROMOLECULES}, author={CHAN, KP and ARGYROPOULOS, DS and WHITE, DM and YEAGER, GW and HAY, AS}, year={1994}, month={Oct}, pages={6371–6375} }
 @article{argyropoulos_heitner_1994, title={P-31 NMR-SPECTROSCOPY IN WOOD CHEMISTRY .6. SOLID STATE P-31 NMR OF TRIMETHYL PHOSPHITE DERIVATIVES OF CHROMOPHORES AND CARBOXYLIC ACIDS PRESENT IN MECHANICAL PULPS - A METHOD FOR THE QUANTITATIVE DETERMINATION OF ORTHO-QUINONES}, volume={48}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1994.48.s1.112}, number={Suppl.}, journal={HOLZFORSCHUNG}, author={ARGYROPOULOS, DS and HEITNER, C}, year={1994}, pages={112–116} }
 @article{argyropoulos_1994, title={QUANTITATIVE P-31 NMR ANALYSIS OF 6 SOLUBLE LIGNINS}, volume={14}, ISSN={["0277-3813"]}, DOI={10.1080/02773819408003086}, abstractNote={Abstract By using a set of lignin samples, which have been subjected to thorough analyses by the international wood chemistry community, the recently developed quantitative method of 31P NMR spectroscopy was comprehensively examined. The values of total phenolic hydroxyl groups and those of total hydroxyl groups were found to favourably compare with those obtained by other laboratories, applying independent methods of analysis. Furthermore, the application of quantitative 31P NMR spectroscopy offered additional detailed structural information for the examined lignins which was in accord with literature accounts for similar wood species and lignin preparations. More specifically, the steam explosion lignins from aspen and yellow poplar woods and that produced by ball milling/enzyme hydrolysis of cottonwood were found to contain relatively high amounts of β-O-4 structures. In contrast, the kraft, organosolv, and the acid hydrolysis processes were found to induce significant chain scission on the resulting lignins. Ball milled cottonwood lignin contained the highest frequency of β-O-4 bonds and the lowest amount of free phenolic hydroxyls. The erythro form of β-O-4 structures were invariably predominant in the lignins from aspen, yellow poplar and cottonwood, in accord with the conclusions of previous reports on hardwood lignins. Thus, the application of quantitative 31P NMR spectroscopy offered the detailed chemical composition of the examined lignins.}, number={1}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={ARGYROPOULOS, DS}, year={1994}, pages={65–82} }
 @article{argyropoulos_1994, title={QUANTITATIVE P-31 NMR ANALYSIS OF LIGNINS, A NEW TOOL FOR THE LIGNIN CHEMIST}, volume={14}, ISSN={["1532-2319"]}, DOI={10.1080/02773819408003085}, abstractNote={Abstract A novel quantitative method has been developed for the determination of the various types of hydroxyl groups present in lignins. The syringyl, guaiacyl and p-hydroxyphenyl free phenolic groups, as well as the primary, and the secondary hydroxyl groups (belonging to individual erythro and threo forms of the aryl-glycerol β-O-4 ether strctures) can be quantitatively determined from a 31P NMR experiment. This is made possible by phosphitylating lignins with 1,3,2 dioxaphospholanyl chloride, followed by 31P NMR spectroscopy, in the presence of a relaxation reagent (chromium acetylacetonate) and an internal standard. The various aspects leading to the development of this technique are discussed together with relevant statistical information pertaining to the reproducibility and quantitative validity of the method. This simple and novel form of spectroscopy may become a valuable resource to the lignin chemist, because it can supply detailed quantitative information about the structure of a soluble lignin sample.}, number={1}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={ARGYROPOULOS, DS}, year={1994}, pages={45–63} }
 @article{argyropoulos_bolker_heitner_archipov_1993, title={P-31 NMR-SPECTROSCOPY IN WOOD CHEMISTRY .4. LIGNIN MODELS - SPIN-LATTICE RELAXATION-TIMES AND SOLVENT EFFECTS IN P-31 NMR}, volume={47}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1993.47.1.50}, number={1}, journal={HOLZFORSCHUNG}, author={ARGYROPOULOS, DS and BOLKER, HI and HEITNER, C and ARCHIPOV, Y}, year={1993}, pages={50–56} }
 @article{argyropoulos_bolker_heitner_archipov_1993, title={P-31 NMR-SPECTROSCOPY IN WOOD CHEMISTRY .5. QUALITATIVE-ANALYSIS OF LIGNIN FUNCTIONAL-GROUPS}, volume={13}, ISSN={["1532-2319"]}, DOI={10.1080/02773819308020514}, abstractNote={Abstract Dioxane lignin isolated from a hardwood (birch, betula verrucosa) and milled wood lignin isolated from a softwood (black spruce, picea mariana) were subjected to a variety of selective reactions to modify some of their functional groups. All the lignins were then treated with 1, 3, 2-dioxaphospholanyl chloride (I) and the 31P NMR spectra of the derivatives were recorded. Most of the 31P NMR signals were assigned from the chemical shifts previously obtained from model compounds. The signals arising from derivatizing me labile protons in carbohydrates, erythro and threo forms in β-O-4 structures, primary hydroxyls in a variety of lignin structures, syringyl and guaiacyl phenolic hydroxyls and those of carboxylic acids were assigned. The alpha benzylic hydroxyls in β-O-4 structures within birch lignin were less reactive toward alkylation than those in spruce lignin, consistent with the findings of previous workers; a difference attributable to the aryl part of the β-O-4 ether. The 31P NMR spectroscopy of lignins derivatized with 1, 3, 2 dioxaphospholanyl chloride is thus shown to have considerable potential for the structural elucidation of lignins. This simple method is recommended for the rapid analysis of soluble lignins.}, number={2}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={ARGYROPOULOS, DS and BOLKER, HI and HEITNER, C and ARCHIPOV, Y}, year={1993}, pages={187–212} }
 @inbook{argyropoulos_1993, title={Phosphorus-31 NMR analysis of steam explosion lignins}, volume={2}, ISBN={0751401714}, DOI={10.1007/978-94-011-1336-6_131}, booktitle={Advances in thermochemical biomass conversion}, publisher={London: Blackie Academic}, author={Argyropoulos, Dimitris}, year={1993}, pages={1625–1633} }
 @article{kimura_kimura_argyropoulos_gray_1992, title={C-13 CP MAS NMR-STUDY OF PHOTODEGRADED STONEGROUND WOOD PULP}, volume={46}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1992.46.4.331}, abstractNote={Des pâtes mecaniques de defibreur de Picea mariana non blanchies et blanchies par H 2 O 2 ont ete soumises a des irradiations severes. On etudie la photodegradation de la lignine dans ces pâtes par spectroscopie 13 C CP/MAS NMR.}, number={4}, journal={HOLZFORSCHUNG}, author={KIMURA, T and KIMURA, F and ARGYROPOULOS, DS and GRAY, DG}, year={1992}, pages={331–336} }
 @article{argyropoulos_heitner_morin_1992, title={P-31 NMR-SPECTROSCOPY IN WOOD CHEMISTRY .3. SOLID-STATE P-31 NMR OF TRIMETHYL PHOSPHITE DERIVATIVES OF CHROMOPHORES IN MECHANICAL PULP}, volume={46}, ISSN={["0018-3830"]}, DOI={10.1515/hfsg.1992.46.3.211}, abstractNote={On a traite des pâtes a haut rendement par du nitrosodisulfonate de potassium pour produire des groupes ortho-quinone, par de l'hydrosulfite de sodium pour reduire les groupes quinone, et par du peroxyde d'hydrogene alcalin pour oxyder les groupes quinone. On a fait reagir ces pâtes et des composes modeles selectionnes avec du phosphite de trimethyle. On etudie les spectres 31 P CP/MAS NMR des composes d'addition resultants, ainsi que les spectres FTIR et UV/visible des pâtes traitees.}, number={3}, journal={HOLZFORSCHUNG}, author={ARGYROPOULOS, DS and HEITNER, C and MORIN, FG}, year={1992}, pages={211–218} }
 @article{archipov_argyropoulos_bolker_heitner_1991, title={P-31 NMR-SPECTROSCOPY IN WOOD CHEMISTRY .1. MODEL COMPOUNDS}, volume={11}, ISSN={["1532-2319"]}, DOI={10.1080/02773819108050267}, abstractNote={Abstract The quantitative reaction in an NMR tube of 1,3,2-dioxaphospholanyl chloride (I) with compounds bearing active hydrogens was explored as a simple method for derivatizing the labile centres known to occur in lignins. Derivatives of phenols, alcohols and carboxylic acids with (I) gave 31P chemical shifts which appeared in different ranges of the NMR spectra. Any ortho substitution onto the aromatic ring of phenols significantly affected the magnitude of the 31P NMR chemical shifts, while para and/or meta substituents had a much smaller effect. A clear distinction between guaiacyl, syringyl and unsubstituted phenolic hydroxyls can thus be made in mixtures of model compounds. Primary alcohols were clearly distinguished from secondary and tertiary alcohols in their derivatives with (I), while different 31P NMR signals for derivatives of erythro and threo forms of lignin-like model compounds were identified. While alcohols, phenols and simple carboxylic acids on reaction with (I) gave derivatives that were substitution products, aldehydes reacted via a distinctly different addition mechanism; ketones did not react at all.}, number={2}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={ARCHIPOV, Y and ARGYROPOULOS, DS and BOLKER, HI and HEITNER, C}, year={1991}, pages={137–157} }
 @article{archipov_argyropoulos_bolker_heitner_1991, title={P-31-NMR SPECTROSCOPY IN WOOD CHEMISTRY .2. PHOSPHITE DERIVATIVES OF CARBOHYDRATES}, volume={220}, ISSN={["0008-6215"]}, DOI={10.1016/0008-6215(91)80005-8}, abstractNote={Selected acyclic and cyclic polyols, monosaccharides, disaccharides, higher oligosaccharides, and model compounds for lignin-carbohydrate complexes were reacted with 1,3,2-dioxaphospholanyl chloride, and the 31P-n.m.r. spectra of the derivatives were obtained in order to correlate the signals with the structural details of the compounds. The derivatives of most of the carbohydrates exhibited spectra containing well resolved signals in the range 138-132 p.p.m., and the number of lines accorded with the number of hydroxyl groups in the respective compounds. The chemical shift values of the phosphorus atoms at C-1 in derivatives of monosaccharides were characteristic for the anomer involved. Since completely resolved spectra with signals characteristic for the sugars and the lignin-related parts, respectively, of relevant model compounds were obtained, the method seems very suitable for the structural elucidation of molecules derived from lignin-carbohydrate complexes. The cyclodextrins (cyclomalto-hexa-, -hepta-, and -octaose) were derivatized, and on examination gave spectra dramatically differing from each other.}, journal={CARBOHYDRATE RESEARCH}, author={ARCHIPOV, Y and ARGYROPOULOS, DS and BOLKER, H and HEITNER, C}, year={1991}, month={Nov}, pages={49–61} }
 @article{argyropoulos_bolker_1987, title={CONDENSATION OF LIGNIN IN DIOXANE-WATER-HCL}, volume={7}, ISSN={["0277-3813"]}, DOI={10.1080/02773818708085249}, abstractNote={Abstract Black spruce sawdust, when treated batchwise, in accordance with the principles of the gel degradation theory, with dioxane: H2O:HCl (90:8:1.8 by volume) at various extents of lignin solubilization, gave a series of lignin fractions. The undialyzed lignin preparations, characterized by Klason lignin, methoxy contents, microanalysis, and U.V. absorptivity, were found to be reasonably uniform in composition. Gel permeation chromatography with a combination of refractive index (RI) and Low Angle Laser Light Scattering (LALLS) detection gave fractions that qualitatively resembled those obtained by the degradation of synthetic model polymer gels. In efforts to quantitatively correlate molecular weights (M w) of these lignins with the existing gel degradation models, however, the problems of lignin fluorescence, association and recondensation were encountered. During the batchwise dioxane:H2O:HCl extraction of wood, irreversible recondensation of the lignin fragments took place, limiting analysis of the results in the context of the gel degradation theory, revealing however, a salient feature of delignification.}, number={1}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={ARGYROPOULOS, DS and BOLKER, HI}, year={1987}, pages={1–23} }
 @article{argyropoulos_bolker_1987, title={GEL DEGRADATION THEORY .1. AN EXPERIMENTAL-VERIFICATION WITH A MODEL TRIFUNCTIONAL NETWORK}, volume={20}, ISSN={["0024-9297"]}, DOI={10.1021/ma00177a046}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGel degradation theory. 1. An experimental verification with a model trifunctional networkDimitris S. Argyropoulos and Henry I. BolkerCite this: Macromolecules 1987, 20, 11, 2915–2922Publication Date (Print):November 1, 1987Publication History Published online1 May 2002Published inissue 1 November 1987https://doi.org/10.1021/ma00177a046RIGHTS & PERMISSIONSArticle Views162Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alertsclose Get e-Alerts}, number={11}, journal={MACROMOLECULES}, author={ARGYROPOULOS, DS and BOLKER, HI}, year={1987}, month={Nov}, pages={2915–2922} }
 @article{argyropoulos_berry_bolker_1987, title={POLYMERIZATION BEYOND THE GEL POINT .1. THE MOLECULAR-WEIGHT OF SOL AS A FUNCTION OF THE EXTENT OF REACTION}, volume={25}, ISSN={["0887-6266"]}, DOI={10.1002/polb.1987.090250602}, abstractNote={Theoretical expressions for describing the weight-average molecular weights of the soluble fractions from polymerizations obtained beyond the gel point were tested experimentally. The theory of branching processes and a recursive approach essentially based on the method of Macosko and Miller were found to be virtually equivalent. The soluble fractions produced from the stoichiometric polymerization of 1,3,5-benzenetriacetic acid (BTA) with decamethylene glycol (DMG) gave molecular weights and distributions in excellent qualitative agreement with the theory. The results are interpreted in terms of intramolecular cyclization, diffusion, and the presence of microgel particles.}, number={6}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={ARGYROPOULOS, DS and BERRY, RM and BOLKER, HI}, year={1987}, month={Jun}, pages={1191–1202} }
 @article{argyropoulos_berry_bolker_1987, title={SPECIES DISTRIBUTION WITHIN THE SOLUBLE PHASE BEYOND THE GEL POINT}, volume={20}, ISSN={["0024-9297"]}, DOI={10.1021/ma00168a022}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpecies distribution within the soluble phase beyond the gel pointDimitris S. Argyropoulos, Richard M. Berry, and Henry I. BolkerCite this: Macromolecules 1987, 20, 2, 357–361Publication Date (Print):February 1, 1987Publication History Published online1 May 2002Published inissue 1 February 1987https://doi.org/10.1021/ma00168a022RIGHTS & PERMISSIONSArticle Views48Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (650 KB) Get e-Alerts Get e-Alerts}, number={2}, journal={MACROMOLECULES}, author={ARGYROPOULOS, DS and BERRY, RM and BOLKER, HI}, year={1987}, month={Feb}, pages={357–361} }
 @article{argyropoulos_bolker_1987, title={THE GEL DEGRADATION THEORY .3. AN EXPERIMENTAL KINETIC VERIFICATION}, volume={7}, ISSN={["0277-3813"]}, DOI={10.1080/02773818708085282}, abstractNote={Abstract Yan and Johnson's kinetic model, which has been developed for the purpose of describing wood delignification, recognizes the polymer network structure of lignin. Their model is experimentally examined with a synthetic network polymer. The starting material was functionalized monodisperse polystyrene crosslinked to yield networks in which the parameters of the theoretical equations were known. By the hydrolytic random cleavage of the crosslinks, kinetic data for this model network degradation experiment was obtained. Thus, the kinetics of this model degradation were found to be adequately described by the Yan and Johnson expressions, which furnish additional support for the gel degradation theory and the model examined herein.}, number={4}, journal={JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY}, author={ARGYROPOULOS, DS and BOLKER, HI}, year={1987}, pages={499–511} }
 @article{argyropoulos_bolker_1986, title={CHARACTERIZATION OF THE SOLUBLE PHASE BEYOND THE GEL POINT}, volume={19}, ISSN={["0024-9297"]}, DOI={10.1021/ma00166a022}, number={12}, journal={MACROMOLECULES}, author={ARGYROPOULOS, DS and BOLKER, HI}, year={1986}, month={Dec}, pages={3001–3003} }
 @article{argyropoulos_bolker_1986, title={KINETICS OF GELATION IN MODEL POLYCONDENSATES}, volume={25}, ISSN={["0196-4321"]}, DOI={10.1021/i300024a013}, abstractNote={Polycondensation modele de l'acide benzenetriacetique-1,3,5 avec le decamethyleneglycol et l'hexadecaneglycol}, number={4}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY PRODUCT RESEARCH AND DEVELOPMENT}, author={ARGYROPOULOS, DS and BOLKER, HI}, year={1986}, month={Dec}, pages={578–582} }
 @article{argyropoulos_lenk_1981, title={CONDENSATION PRODUCTS FROM IMIDOBIS(SULFURYL CHLORIDE)}, volume={26}, ISSN={["0021-8995"]}, DOI={10.1002/app.1981.070260921}, abstractNote={A study of model compounds and polycondensation products derived from imidobis(sulfuryl chloride) (IBSC), HN(SO2Cl)2, has been carried out and their structures determined. The model compounds were reaction products of IBSC with aniline or ethyl alcohol. Polymeric products were obtained by polycondensations with (1) p-phenylenediamine and (2) 2,2-bis(4'-hydroxyphenyl)-propane. The products were characterized by elemental analysis, infrared, NMR, DSC, TGA, and viscometry data.}, number={9}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={ARGYROPOULOS, D and LENK, RS}, year={1981}, pages={3073–3084} }
 @article{mazur_argyropoulos, title={31P NMR spectroscopy in wood chemistry, Part VII, Studies toward elucidating the phosphorus relaxation mechanism of phosphitylated lignins}, volume={29}, number={5}, journal={Cellulose Chemistry and Technology}, author={Mazur, M. and Argyropoulos, D. S.}, pages={589–601} }
 @article{argyropoulos, title={31P NMR spectroscopy in wood chemistry: A new tool for the lignin chemist}, volume={9}, journal={Polyphenols Actualite}, author={Argyropoulos, D. S.}, pages={19–21} }
 @inbook{jurasek_argyropoulos, title={A detailed study of the alkaline oxidative degradation of a residual kraft lignin model compound}, volume={785}, ISBN={084123738}, booktitle={Oxidative delignification chemistry: Fundamentals and catalysis}, publisher={Washington, DC: ACS Books}, author={Jurasek, L. and Argyropoulos, D. S.}, pages={130–148} }
 @article{argyropoulos_bolker, title={A facile synthesis of monodisperse carboxylated polystyrene and derivatives}, volume={187}, journal={Die Makromolekulare Chemie}, author={Argyropoulos, D. S. and Bolker, H. I.}, pages={1887–1894} }
 @article{moore_argyropoulos, title={A pilot plant trial using in situ peroxyborate for the brightness retention of TMP}, volume={83}, number={11}, journal={TAPPI Journal}, author={Moore, D. B. and Argyropoulos, D. S.}, pages={63} }
 @article{jiang_argyropoulos, title={A stereoselective degradation of arylglycerol-beta-aryl ethers during kraft pulping}, volume={20}, number={7}, journal={Journal of Pulp and Paper Science}, author={Jiang, Z. and Argyropoulos, D. S.}, pages={J183–188} }
 @article{argyropoulos_jurasek_kristofova_xia_sun_paulus, title={Abundance and reactivity of dibenzodioxocins in softwood lignin}, volume={50}, journal={Journal of Agricultural and Food Chemistry}, author={Argyropoulos, D. S. and Jurasek, L. and Kristofova, L. and Xia, Z.-C. and Sun, Y.-J. and Paulus, E.}, pages={585–666} }
 @article{suchy_argyropoulos, title={Activation of alkaline peroxide delignification using a vanadium peroxo complex}, volume={83}, number={6}, journal={TAPPI Journal}, author={Suchy, M. and Argyropoulos, D. S.}, pages={1–9} }
 @book{advances in lignocellulosics characterization, ISBN={0898523575}, publisher={Atlanta: TAPPI Press} }
 @inbook{billa_argyropoulos_koukios, title={Advances in residual lignin characterization combining 31P NMR and fluorescence spectroscopy by chemometrics}, ISBN={0898523575}, booktitle={Advances in lignocellulosics characterization}, publisher={Atlanta: TAPPI Press}, author={Billa, E. and Argyropoulos, D. S. and Koukios, E.}, pages={131–144} }
 @article{heitner_argyropoulos_miles_karnis_kerr, title={Alkaline sulphite ultra-high yield pulping of aspen chips: A comparison of steam explosion and conventional chemimechanical pulping}, volume={19}, number={2}, journal={Journal of Pulp and Paper Science}, author={Heitner, C. and Argyropoulos, D. S. and Miles, K. and Karnis, A. and Kerr, B.}, pages={J58–70} }
 @article{wu_argyropoulos, title={An improved method for isolating residual kraft lignin in high yield purity}, volume={19}, number={Sup. 2}, journal={Journal of Tianjin University of Science & Technology}, author={Wu, S. and Argyropoulos, D. S.}, pages={108–114} }
 @inbook{argyropoulos, title={Applications of quantitative 31P NMR to pulping, bleaching and yellowing}, ISBN={0898523575}, booktitle={Advances in lignocellulosics characterization}, publisher={Atlanta: TAPPI Press}, author={Argyropoulos, D. S.}, pages={109–129} }
 @article{souza_bouchard_methot_berry_argyropoulos, title={Carbohydrates in oxygen delignification. Part I: Changes in cellulose crystallinity}, volume={28}, number={5}, journal={Journal of Pulp and Paper Science}, author={Souza, I. J. and Bouchard, J. and Methot, M. and Berry, R. and Argyropoulos, D. S.}, pages={167–170} }
 @article{suchy_argyropoulos, title={Catalysis and activation of oxygen and peroxide delignification of chemical pulps: A review}, volume={1}, number={2}, journal={TAPPI Journal}, author={Suchy, M. and Argyropoulos, D. S.}, pages={1–18} }
 @inbook{suchy_argyropoulos, title={Catalysis and activation of oxygen and peroxide delignification of chemical pulps: A review}, volume={785}, ISBN={084123738}, booktitle={Oxidative delignification chemistry: Fundamentals and catalysis}, publisher={Washington, DC: ACS Books}, author={Suchy, M. and Argyropoulos, D. S.}, pages={2–48} }
 @article{argyropoulos, title={Cellulose and Renewable Materials Division: A renewed outlook for the future}, volume={9}, number={2}, journal={Cellulose}, author={Argyropoulos, D. S.}, pages={103–104} }
 @article{ma_zhou_li_argyropoulos, title={Conversion of fructose to 5-hydroxymethyl-furfural with a functionalized ionic liquid}, volume={7}, number={1}, journal={BioResources}, author={Ma, H. and Zhou, B. and Li, Y. Q. and Argyropoulos, D. S.}, pages={533–544} }
 @article{argyropoulos, title={Correction to Determination of arylglycerol-beta-aryl ethers and other linkages in lignins using DFRC/31P NMR}, volume={49}, number={3}, journal={Journal of Agricultural and Food Chemistry}, author={Argyropoulos, D. S.}, pages={1069} }
 @article{colodette_gomide_robles_almeida_mehlman_brito_argyropoulos, title={Effect of the pulping process on pulp bleachability with ECF, Z-ECF and TCF bleaching sequences}, volume={52}, number={5}, journal={Canadian Journal of Chemistry}, author={Colodette, J. L. and Gomide, J. L. and Robles, Y. A. M. and Almeida, J. M. and Mehlman, S. K. and Brito, A. C. H. and Argyropoulos, D. S.}, pages={368–374} }
 @article{sun_argyropoulos, title={Fundamentals of high pressure oxygen and low pressure oxygen-peroxide (EOP) delignification of softwood and hardwood kraft pulps: A comparison}, volume={21}, number={6}, journal={Journal of Pulp and Paper Science}, author={Sun, Y. and Argyropoulos, D. S.}, pages={J175–190} }
 @article{wang_jiang z.-h._argyropoulos, title={Isolation and characterization of lignin extracted from softwood kraft pulp after xylanase treatment}, volume={23}, number={2}, journal={Journal of Pulp and Paper Science}, author={Wang, J. and Jiang Z.-H. and Argyropoulos, D. S.}, pages={J47–51} }
 @article{jiang_argyropoulos, title={Isolation and characterization of residual lignin in kraft pulp}, volume={25}, number={1}, journal={Journal of Pulp and Paper Science}, author={Jiang, J. and Argyropoulos, D. S.}, pages={25–29} }
 @article{argyropoulos_sun_paulus, title={Isolation of residual kraft lignin in high yield and purity}, volume={28}, number={2}, journal={Journal of Pulp and Paper Science}, author={Argyropoulos, D. S. and Sun, Y.-J. and Paulus, E.}, pages={50–54} }
 @article{argyropoulos_hortling_poppius-levlin_sun_mazur, title={MILOX pulping, lignin characterization by 31P NMR spectroscopy and oxidative degradation}, volume={10}, number={1}, journal={Nordic Pulp & Paper Research Journal}, author={Argyropoulos, D. S. and Hortling, B. and Poppius-Levlin, K. and Sun, Y and Mazur, M.}, pages={68–73} }
 @book{materials, chemicals and energy from forest biomass, volume={954}, ISBN={9780841239814}, journal={ACS Symposium Series}, publisher={Washington, DC: ACS Books} }
 @article{koda_gaspar_yu_argyropoulos, title={Molecular weight-functional group relations in softwood residual kraft lignins}, volume={59}, number={6}, journal={Holzforschung}, author={Koda, K. and Gaspar, A. R. and Yu, L. and Argyropoulos, D. S.}, pages={612–619} }
 @article{van lierop_jiang_chen_argyropoulos_berry, title={On the efficiency of hydrogen peroxide use in ECF bleaching}, volume={26}, number={7}, journal={Journal of Pulp and Paper Science}, author={Van Lierop, B. and Jiang, Z. H. and Chen, J. and Argyropoulos, D. S. and Berry, R. M.}, pages={255–259} }
 @article{argyropoulos_peng, title={On the interaction of UV screens with the lignocellulosic substrate}, volume={7}, number={2}, journal={Photochemistry and Photobiology}, author={Argyropoulos, D. S. and Peng, P.}, pages={149–156} }
 @article{jurasek_argyropoulos, title={On the reactivity of lignin models with oxygen-centered radicals. I. Computations of proton and electron affinities and O-H bond dissociation energies}, volume={40}, number={3-4}, journal={Cellulose Chemistry and Technology}, author={Jurasek, L. and Argyropoulos, D. S.}, pages={165–172} }
 @article{argyropoulos_berry_bolker, title={Polymerization beyond the gel point, Part II}, volume={188}, journal={Die Makromolekulare Chemie}, author={Argyropoulos, D. S. and Berry, R. M. and Bolker, H. I.}, pages={1985–1987} }
 @article{mattinen_suortti_gosselink_argyropoulos_evtuguin_suurnakki_jong_tamminen, title={Polymerization of different lignins by Lacasse}, volume={3}, number={2}, journal={BioResources}, author={Mattinen, M.-L. and Suortti, T. and Gosselink, R. and Argyropoulos, D. S. and Evtuguin, D. and Suurnakki, A. and Jong, E. and Tamminen, T.}, pages={549–565} }
 @inbook{argyropoulos_hodd_wright, title={Property variations with crosslink density in glycidyl amines based on 4-4'-diamino diphenyl methane}, volume={2}, ISBN={0471262439}, booktitle={Thermal analysis: Proceedings of the Seventh International Conference on Thermal Analysis}, publisher={New York: Wiley}, author={Argyropoulos, D. S. and Hodd, K. H. and Wright, W. W.}, pages={1099–1105} }
 @article{argyropoulos_sun_berry_bouchard, title={Reactions of dimethyldioxirane with lignin model compounds}, volume={22}, number={3}, journal={Journal of Pulp and Paper Science}, author={Argyropoulos, D. S. and Sun, Y and Berry, R. M. and Bouchard, J.}, pages={J84–90} }
 @inbook{saladino_crestini_argyropoulos, title={Recent advances in the oxidative valorisation of low molecuar weight cellulose derivatives}, volume={954}, ISBN={9780841239814}, booktitle={Materials, chemicals and energy from forest biomass}, publisher={Washington, DC: ACS Books}, author={Saladino, R. and Crestini, C. and Argyropoulos, D. S.}, pages={262–279} }
 @article{saake_argyropoulos_faix, title={Structural investigations of synthetic lignins (DHP's) as a function of molar mass and mode of preparation}, volume={43}, number={2}, journal={Phytochemistry}, author={Saake, B. and Argyropoulos, D. S. and Faix, O.}, pages={499–507} }
 @inbook{scallan_katz_argyropoulos, title={The conductometric titration of cellulosic fibres}, ISBN={0471512567}, booktitle={Cellulose and wood: Chemistry and technology}, publisher={New York: Wiley}, author={Scallan, A. M. and Katz, S. and Argyropoulos, D. S.}, pages={1457–1471} }
 @article{argyropoulos_bolker, title={The gel degradation theory. Part II, An experimental verification with model networks formed by the random crosslinking of monodisperse primary chains}, volume={189}, journal={Die Makromolekulare Chemie}, author={Argyropoulos, D. S. and Bolker, H. I.}, pages={607–618} }
 @article{argyropoulos_liu, title={The role and fate of lignin?s condensed structures during oxygen delignification}, volume={26}, number={3}, journal={Journal of Pulp and Paper Science}, author={Argyropoulos, D. S. and Liu, Y.}, pages={107–113} }
 @inproceedings{argyropoulos_filpponen, title={The use of cellulose nanocrystals as scaffolds for nanodevices; supramolecular chemistry using nature's most ambundant template}, booktitle={Research Progress in Paper Industry and Biorefinery (4th ISETPP), vols 1-3}, author={Argyropoulos, D. S. and Filpponen, I.}, pages={26–29} }
 @article{argyropoulos_heitner, title={Ultra-high yield pulping. Part VII, The effect of pH during impregnation on the quality of lightly sulphonated TMP}, volume={17}, number={5}, journal={Journal of Pulp and Paper Science}, author={Argyropoulos, D. S. and Heitner, C.}, pages={J137–143} }
 @article{argyropoulos, title={What's in a name}, volume={20}, journal={Chemical & Engineering News}, author={Argyropoulos, D. S.}, pages={51} }
 @article{colodette_gomide_gleysys_kogan_jaskelainen_argyropoulos, title={Yield and bleachability of hardwood and softwood kraft/polysulfide pulps}, volume={102}, number={9}, journal={Pulp & Paper Canada}, author={Colodette, J. and Gomide, J. L. and Gleysys, K. and Kogan, J. and Jaskelainen, A.-S. and Argyropoulos, D. S.}, pages={T269–272} }