@article{heitman_castillo_smyth_crozier_2018, title={Stem, Leaf, and Panicle Yield and Nutrient Content of Biomass and Sweet Sorghum}, volume={110}, ISSN={["1435-0645"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85052711959&partnerID=MN8TOARS}, DOI={10.2134/agronj2018.03.0178}, abstractNote={Core Ideas
Sorghum is a potential dedicated bioenergy crop both from biomass and sugar yields.
Increasing rates of N fertilizer affected biomass yield and nutrient removal for sorghum cultivar ES5200 by partitioning resources primarily toward the stem component.
For sorghum M81‐E, the seed head component accounted for a greater proportion of biomass, compared with sorghum ES5200, and biomass yield and nutrients were more evenly distributed among the three components.
Returning the leaf and seed head components back to the field to enhance soil fertility has the potential to provide at least 45, 7, and, 26 kg ha−1 of N, P, and K, respectively.
}, number={5}, journal={AGRONOMY JOURNAL}, author={Heitman, A. J. and Castillo, M. S. and Smyth, T. J. and Crozier, C. R.}, year={2018}, pages={1659–1665} }
 @article{wang_jot smyth_crozier_gehl_heitman_2018, title={Yield and Nitrogen Removal of Bioenergy Grasses as Influenced by Nitrogen Rate and Harvest Management in the Coastal Plain Region of North Carolina}, volume={11}, ISSN={1939-1234 1939-1242}, url={http://dx.doi.org/10.1007/S12155-017-9876-X}, DOI={10.1007/s12155-017-9876-x}, number={1}, journal={BioEnergy Research}, publisher={Springer Science and Business Media LLC}, author={Wang, Zan and Jot Smyth, T. and Crozier, Carl R. and Gehl, Ronald J. and Heitman, Adam J.}, year={2018}, month={Mar}, pages={44–53} }
 @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{lee_pawlak_heitmann_2012, title={Dimensional and hygroexpansive behaviors of cellulose microfi brils (MFs) from kraft pulp-based fibers as a function of relative humidity}, volume={66}, ISSN={["1437-434X"]}, DOI={10.1515/hf-2011-0129}, abstractNote={Abstract}, number={8}, journal={HOLZFORSCHUNG}, author={Lee, Jung Myoung and Pawlak, Joel J. and Heitmann, John A.}, year={2012}, month={Dec}, pages={1001–1008} }
 @article{lee_pawlak_heitmann_2010, title={Longitudinal and concurrent dimensional changes of cellulose aggregate fibrils during sorption stages}, volume={61}, ISSN={["1873-4189"]}, DOI={10.1016/j.matchar.2010.02.007}, abstractNote={Atomic force microscopy (AFM) studies of the dimensional changes of cellulose microfibril materials, called cellulose aggregate fibrils (approx. 100 µm × 3 µm × 300 nm), exposed to two distinct relative humidities of 80% and 23% for 24 h and then suddenly subjected to 50% RH and 23 °C show that the fibrils are responsive to the surrounding environments in a nonspecific fashion. AFM images (10 µm × 10 µm) of the individual straight cellulose aggregate fibrils were taken as a function of elapsed time during both desorption and adsorption of moisture. The longitudinal distance between discrete natural defects observed on the cellulose aggregate fibrils as well as the width, cross-sectional area, and height of the cellulose aggregate fibril were measured from the AFM images. The length of the cellulose aggregate fibrils was found to have reduced after exposure to either high or low relative humidity, and then placement in ambient conditions. Over time in ambient conditions, the cellulose aggregate fibrils progressively relaxed to their original length during both desorption and adsorption of moisture. However, the relaxation rate during adsorption was faster than that during desorption. The possible explanations for this phenomenon are discussed including the sample preparation method, volume conservation, entropy elasticity, and free volume theory. The changes in the width, height, and cross-sectional area are also discussed.}, number={5}, journal={MATERIALS CHARACTERIZATION}, author={Lee, Jung Myoung and Pawlak, Joel J. and Heitmann, John A.}, year={2010}, month={May}, pages={507–517} }
 @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{chen_park_heitmann_hubbe_2009, title={Importance of Cellulosic Fines Relative to the Dewatering Rates of Fiber Suspensions}, volume={48}, ISSN={["0888-5885"]}, DOI={10.1021/ie9006613}, abstractNote={When cellulosic fines are present in significant amounts, they can have a dominant influence on dewatering. Pulp suspensions drain rapidly if the fines have been removed. In this study, the dependency of gravity dewatering rates on the level and properties of cellulosic fine matter was quantified. Bleached hardwood kraft pulp was used as a source of primary fines (collected before refining) and secondary fines (collected after refining of fines-free fiber suspensions). Fractions of fine matter also were obtained from chemithermomechanical (CTMP) pulp. Size distributions of these fines were characterized using a laser diffraction method. Results were explainable by a mechanism in which unattached fines are able to move relative to adjacent fibers during the dewatering and consolidation of a mat of fibers. Due to such movement, fines end up in locations where they plug drainage channels in the mat. The contribution of the fines to dewatering increased in inverse proportion to particle size and with increasi...}, number={20}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Chen, Hao and Park, Andrew and Heitmann, John A. and Hubbe, Martin A.}, year={2009}, month={Oct}, pages={9106–9112} }
 @article{hu_heitmann_rojas_2009, title={In Situ Monitoring of Cellulase Activity by Microgravimetry with a Quartz Crystal Microbalance}, volume={113}, ISSN={["1520-6106"]}, DOI={10.1021/jp907155v}, abstractNote={Quartz crystal microgravimetry (QCM) was used to investigate the interactions between cellulase enzymes and model cellulose substrates. The substrates consisted of thin films of cellulose that were spin-coated onto polyvinylamine (PVAm) precoated quartz crystal sensors carrying conductive gold surfaces. In QCM the quartz crystals are piezoelectrically driven and the frequency and dissipation shifts allow monitoring of substrate hydrolysis at various temperatures and enzyme concentrations in situ and in real time. The changes in frequency of cellulose-coated quartz resonators during their incubation in cellulase solutions were related to contributions from the liquid phase properties, the adsorptions of cellulase enzymes, and the hydrolysis of the substrate. Cellulase adsorption was found to be nonspecific and irreversible on gold-, PVAm-, and cellulose-coated quartz crystal sensors. The contribution to frequency shifts due to the bulk fluid properties of the cellulase solutions (at concentrations lower than 0.5 mg/mL) was minimal compared to the frequency shifts produced by cellulase binding. The maximum frequency decreases were fitted to a Langmuir model. The adsorption constant and the maximum adsorption were estimated by the fitting parameters of this model. The hydrolysis process was modeled by using a dose-response model that was then used to estimate the maximum hydrolysis rate, to compare the relative effects of temperature on adsorption and hydrolysis rate, and to obtain the apparent activation energy of cellulose hydrolysis. The hydrolysis rate increased with incubation temperature while apparent adsorption decreased. The apparent activation energy for the hydrolysis of the cellulose films employed was calculated to be 37 kJ/mol.}, number={44}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Hu, Gang and Heitmann, John A., Jr. and Rojas, Orlando J.}, year={2009}, month={Nov}, pages={14761–14768} }
 @article{hu_heitmann_rojas_2009, title={Quantification of Cellulase Activity Using the Quartz Crystal Microbalance Technique}, volume={81}, ISSN={["1520-6882"]}, DOI={10.1021/ac802318t}, abstractNote={The development of more efficient utilization of biomass has received increased attention in recent years. Cellulases play an important role in processing biomass through advanced biotechnological approaches. Both the development and the application of cellulases require an understanding of the activities of these enzymes. A new method to determine the activity of cellulase has been developed using a quartz crystal microbalance (QCM) technique. We compare the results from this technique with those from the IUPAC (International Union of Pure and Applied Chemistry) dinitrosalicylic acid (DNS) standard method and also from biccinchoninic acid and ion chromatography methods. It is shown that the QCM technique provides results closer to those obtained by measuring the actual reducing sugars. The elimination of the use of color development in the standard redox methods makes the QCM platform easier to implement; it also allows more flexibility in terms of the nature of the substrate. Finally, validation of the proposed method was carried out by relating the crystallinity of different substrates to the cellulase activity. Numerical values of cellulase activities measured with the QCM method showed that celluloses with higher crystallinity indices were hydrolyzed slower and to a lower extent than those of lower crystallinity indices for the cellulase mixtures examined.}, number={5}, journal={ANALYTICAL CHEMISTRY}, author={Hu, Gang and Heitmann, John A., Jr. and Rojas, Orlando J.}, year={2009}, month={Mar}, pages={1872–1880} }
 @article{bastidas_pawlak_venditti_heitmann_hubbe_kadla_2008, title={A colloidal probe microscopy study of cellulose/gypsum interactions}, volume={59}, ISSN={["1044-5803"]}, DOI={10.1016/j.matchar.2006.12.007}, abstractNote={Drywall, which is made primarily of a calcium sulfate dihydrate (gypsum) core with paper on both sides, is one of the most widely used construction materials. Because board failure often occurs at the gypsum core/paper interface, it has become important to know the exact nature of the gypsum/cellulose bond and how crystal morphology affects it. This study provides data about the nature of this interaction by means of AFM and Colloidal Probe Microscopy. These methods made it possible to distinguish among the different crystal faces and their respective interactions with cellulose. Measured in air, the adhesive forces between the AFM tip and the different faces varied according to f(010) < f(120) < f(111) at 50% relative humidity. The differences in adhesive force with the different gypsum crystals face can be attributed to the differences in surface chemistry. The information obtained in this study will help guide improvements in the gypsum wallboard production process to obtain better bonding between the crystal and the paper.}, number={2}, journal={MATERIALS CHARACTERIZATION}, author={Bastidas, Juan C. and Pawlak, Joel J. and Venditti, Richard A. and Heitmann, John A. and Hubbe, Martin A. and Kadla, John F.}, year={2008}, month={Feb}, pages={144–150} }
 @article{hu_heitmann_rojas_2008, title={Feedstock pretreatment strategies for producing ethanol from wood, bark, and forest residues}, volume={3}, number={1}, journal={BioResources}, author={Hu, G. and Heitmann, J. A. and Rojas, O. J.}, year={2008}, pages={270–294} }
 @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{lee_heitmann_pawlak_2007, title={Local morphological and dimensional changes of enzyme-degraded cellulose materials measured by atomic force microscopy}, volume={14}, ISSN={["0969-0239"]}, DOI={10.1007/s10570-007-9172-6}, number={6}, journal={CELLULOSE}, author={Lee, Jung Myoung and Heitmann, John A. and Pawlak, Joel J.}, year={2007}, month={Dec}, pages={643–653} }
 @article{lee_heitmann_pawlak_2007, title={Rheology of carboxymethyl cellulose solutions treated with cellulases}, volume={2}, number={1}, journal={BioResources}, author={Lee, J. M. and Heitmann, J. A. and Pawlak, J. J.}, year={2007}, pages={20–33} }
 @article{lee_heitmann_pawlak_2007, title={Technique for the measurement of dimensional changes of natural microfibril materials under variable humidity environments}, volume={445}, DOI={10.1016/j.msea.2006.09.096}, abstractNote={An algorithm was developed to analyze the dimensions of line scan data of step-shaped disconitunities acquired with an atomic force microscope. The effect of a number of AFM parameters on the quantitative imaging of step features was discussed. Quantitiative imaging using AFM was shown to be very reproducible as five successive scans of a standard step height grating produced less than 3% variation in measured parameters. A cellulose microfibril, called cellulose aggregate fibril (CAF), with dimensions of ∼50,000 nm × 2000 nm × 300 nm derived from papermaking fibers was scanned under cyclic relative humdity conditions with the relative humidity starting at 50% then raising to 80% followed by a decrease in the relative humidity to 28%. Changes in the width of the CAF were weakly correlated with changes in the relative humdity, while changes in the height and area of the CAF were positively correlated with the relative humdity. The length of the CAF was negatively correlated with the given relative humdity cycle. These findings have significant implications in paper dimensional stability and the engineering of cellulose micro and nano-fiber composites.}, journal={Materials Science & Engineering. A, Structural Materials: Properties, Microstructure and Processing}, author={Lee, J. M. and Heitmann, J. A. and Pawlak, Joel}, year={2007}, pages={632–640} }
 @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{hubbe_tripattharanan_heitmann_venditti_2006, title={The Positive Pulse Jar (PPJ): A flexible device for retention studies}, volume={88}, number={1}, journal={Paperi Ja Puu = Paper and Timber}, author={Hubbe, M. A. and Tripattharanan, T. and Heitmann, J. A. and Venditti, R. A.}, year={2006}, pages={39–45} }
 @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{tripattharanan_hubbe_venditti_heitmann_2004, title={Effect of idealised flow conditions on retention aid performance. Part 1, Cationic acrylamide copolymer}, volume={57}, number={5}, journal={Appita Journal}, author={Tripattharanan, T. and Hubbe, M. A. and Venditti, R. A. and Heitmann, J. A.}, year={2004}, month={Sep}, pages={404–410} }
 @article{tripattharanan_hubbe_heitmann_venditti_2004, title={Effect of idealised flow conditions on retention aid performance. Part 2, Polymer bridging, charged patches, and charge neutralisation}, volume={57}, number={6}, journal={Appita Journal}, author={Tripattharanan, T. and Hubbe, M. A. and Heitmann, J. A. and Venditti, R. A.}, year={2004}, pages={448–454} }
 @article{zhang_hubbe_venditti_heitmann_2004, title={Effects of sugar addition before drying on the wet flexibility of redispersed kraft fibres}, volume={30}, number={1}, journal={Journal of Pulp and Paper Science}, author={Zhang, M. and Hubbe, M. A. and Venditti, R. A. and Heitmann, J. A.}, year={2004}, pages={29–34} }
 @article{zhang_hubbe_venditti_heitmann_2004, title={Refining to overcome effects of drying unbleached Kraft fibers in the presence or absence of sugar}, volume={13}, number={2}, journal={Progress in Paper Recycling}, author={Zhang, M. and Hubbe, M. A. and Venditti, R. A. and Heitmann, J. A.}, year={2004}, pages={5–12} }
 @article{chen_heitmann_chang_hubbe_venditti_2004, title={The effect of paper additives on toner agglomeration during the recycling process}, volume={13}, number={14}, journal={Progress in Paper Recycling}, author={Chen, J. and Heitmann, J. A. and Chang, H.-M. and Hubbe, M. A. and Venditti, R. A.}, year={2004}, pages={16–23} }
 @article{chen_heitmann_hubbe_2003, title={Dependency of polyelectrolyte complex stoichiometry on the order of addition. 1. Effect of salt concentration during streaming current titrations with strong poly-acid and polybase}, volume={223}, ISSN={["0927-7757"]}, DOI={10.1016/S0927-7757(03)00222-X}, abstractNote={Titrations were carried out between solutions of a strong poly-acid (polyvinylsulfate, potassium salt) and a strong poly-base (poly-diallyldimethylammonium chloride (poly-DADMAC)) over a range of salt concentrations. Streaming current (SC) analysis of the titration endpoints appeared to show increasing deviations from 1:1 stoichiometry of complexation with increased salt. The results depended on the direction of the titration, such that a stoichiometric excess of the titrant (second additive) was required to achieve a SC reading of zero. These symmetrical results, depending on the order of addition, were obtained despite the fact that the plastic surfaces of the SC device had a slight negative charge and differing adsorption tendencies for the two kinds of polymer. A qualitative model of molecular events, based on non-equilibrium entrapment of non-complexed polymer segments was found to be inconsistent with results of tests carried out over a range of initial polymer concentration. Results were better described by a qualitative model involving formation of polyelectrolyte complexes (PECs) in solution, in which near-stoichiometric core complexes are stabilized by an excess of the second additive on their surface. Implications of the latter model were compared with the results of turbidimetric tests, aqueous contact angles on polymer-treated plastic surfaces, and microelectrophoresis of PECs. Results of this study have consequences for interpretation of polyelectrolyte titrations, as well as for industrial operations that involve the mixing of oppositely charged polyelectrolytes.}, number={1-3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Chen, JH and Heitmann, JA and Hubbe, MA}, year={2003}, month={Aug}, pages={215–230} }
 @article{zhang_hubbe_venditti_heitmann_2002, title={Can recycled kraft fibres benefit from chemical addition before they are first dried?}, volume={55}, number={2}, journal={Appita Journal}, author={Zhang, M. and Hubbe, M. A. and Venditti, R. A. and Heitmann, J. A.}, year={2002}, pages={135–144} }
 @inproceedings{zhang_hubbe_venditti_heitmann_2001, title={Effect of chemical pretreatments of never-dried pulp on the strength of recycled linerboard}, booktitle={Proceedings, TAPPI Papermakers Conference}, publisher={TAPPI}, author={Zhang, M. and Hubbe, M. A. and Venditti, R. A. and Heitmann, J. A.}, year={2001} }
 @misc{jackson_joyce_heitmann_2001, title={Method for making dissolving pulp from paper products containing hardwood fibers}, volume={6,254,722}, number={2001 July 3}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Jackson, L. S. and Joyce, T. W. and Heitmann, J. A., Jr.}, year={2001} }
 @article{jacobs-young_gustafson_heitmann_2000, title={Conventional kraft pulping using enzyme pretreatment technology: role of diffusivity in enhancing pulp uniformity}, volume={82}, number={2}, journal={Paperi Ja Puu = Paper and Timber}, author={Jacobs-Young, C. J. and Gustafson, R. R. and Heitmann, J. A.}, year={2000}, pages={114–119} }
 @article{kaya_heitmann_joyce_2000, title={Influence of lignin and its degradation products on enzymatic hydrolysis of xylan}, volume={80}, ISSN={["0168-1656"]}, DOI={10.1016/S0168-1656(00)00265-0}, abstractNote={The influence of lignin, lignin model compounds, and black liquor from the kraft pulping process on the hydrolysis of xylan by xylanase was investigated. Addition of vanillic acid, acetovanillone, and protocatechuic acid increased the rate of hydrolysis of xylan by as much as 18-50% at low concentrations, but reached maxima at about 0.05% concentration. Addition of vanillin caused a 15% improvement in xylan hydrolysis, while addition of guaiacol more than doubled the hydrolysis rate. Increasing concentrations of either lignin or black liquor also increased the hydrolysis rate of xylan. Circular dichroism spectroscopy indicated a change in the structure of xylanase in the presence of black liquor.}, number={3}, journal={JOURNAL OF BIOTECHNOLOGY}, author={Kaya, F and Heitmann, JA and Joyce, TW}, year={2000}, month={Jul}, pages={241–247} }
 @inproceedings{zhang_hubbe_venditti_heitmann_2000, title={Loss of bonding strength dye to drying and repulping of Kraft fibers: Effects of chemical additives}, ISBN={9570258969}, booktitle={Proceedings, International Symposium on Environmentally Friendly and Emerging Technologies for a Sustainable Pulp and Paper Industry, Taipei, Taiwan, April 25-27, 2000}, publisher={Taipei, Taiwan: Taiwan Forestry Research Institute; Taiwan Technical Association of Pulp and Paper Industry}, author={Zhang, M. and Hubbe, M. A. and Venditti, R. A. and Heitmann, J. A.}, editor={Su, Y.-C. and E. I. C. WangEditors}, year={2000} }
 @article{gerber_heitmann_joyce_buchert_siika-aho_1999, title={Adsorption of hemicellulases onto bleached kraft fibers}, volume={67}, ISSN={["0168-1656"]}, DOI={10.1016/S0168-1656(98)00163-1}, abstractNote={The presence of a cellulose binding domain was the main factor which influenced the adsorption of two Trichoderma reesei mannanases and a Trichoderma longibrachiatum xylanase onto bleached kraft fibers. The mannanase containing the binding domain adsorbed to a much greater extent than the mannanase and xylanase without binding domains. Once-dried fibers exhibited lower hemicellulase adsorption than the never-dried fibers. The adsorption onto once-dried fibers was only 30–50% the amount adsorbed onto virgin fibers. Adjustment of the ionic strength and pH of treatment was used to modify the charge on the fibers. Ionic strength had opposite effects on mannanase and mannanase core adsorption. Mannanase adsorption increased at high ionic strengths, while the mannanase core adsorption decreased. An increase in pH and fiber charge significantly enhanced the adsorption of xylanase.}, number={1}, journal={JOURNAL OF BIOTECHNOLOGY}, author={Gerber, PJ and Heitmann, JA and Joyce, TW and Buchert, J and Siika-aho, M}, year={1999}, month={Jan}, pages={67–75} }
 @article{kaya_heitmann_joyce_1999, title={Effect of dissolved lignin and related compounds on the enzymatic hydrolysis of cellulose model compound}, volume={33}, number={3-4}, journal={Cellulose Chemistry and Technology}, author={Kaya, F. and Heitmann, J. A. and Joyce, T. W.}, year={1999}, pages={203–213} }
 @misc{heitmann_joyce_1999, title={Method of cleaning papermaking felts with enzymes}, volume={5,961,735}, number={1999 Oct. 5}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Heitmann, J. A., Jr. and Joyce, T. W.}, year={1999} }
 @inbook{jacobs-young_heitmann_venditti_1998, title={Conventional kraft pulping using enzyme pretreatment technology: Role of chip thickness, specie and enzyme combinations}, booktitle={Innovative advances in the forest products industries: the 1997 Forest Products Symposium}, publisher={New York: American Institute of Chemical Engineers}, author={Jacobs-Young, C. J. and Heitmann, J. A. and Venditti, R. A.}, year={1998}, pages={1–15} }
 @article{gerber_joyce_heitmann_siika-aho_buchert_1997, title={Adsorption of a Trichoderma reesei endoglucanase and cellobiohydrolase onto bleached Kraft fibres}, volume={4}, ISSN={["1572-882X"]}, DOI={10.1023/A:1018444008305}, number={4}, journal={CELLULOSE}, author={Gerber, PJ and Joyce, TW and Heitmann, JA and Siika-Aho, M and Buchert, J}, year={1997}, month={Dec}, pages={255–268} }
 @article{gerber_heitmann_joyce_1997, title={Purification and characterization of xylanases from Trichoderma}, volume={61}, ISSN={["1873-2976"]}, DOI={10.1016/S0960-8524(97)00052-7}, abstractNote={Xylanase preparations free of cellulase contamination are often required for applications in the pulp and paper industry. Xylanases from Trichoderma have been purified and characterized in an effort to better understand the behavior of the various components of the xylanolytic system in order to optimize their effect. However, purification and characterization of xylanases from Trichoderma species are still incomplete. This review organizes current techniques for xylanase purification and examines the properties of xylanases that have been previously characterized. Problems with assays, lyophilizing, gel permeation behavior, gel electrophoresis and developing are also noted. From this review, a strategy for the isolation of an endoxylanase from a commercial preparation of T. longibrachiatum is developed.}, number={2}, journal={BIORESOURCE TECHNOLOGY}, author={Gerber, PJ and Heitmann, JA and Joyce, TW}, year={1997}, month={Aug}, pages={127–140} }
 @inproceedings{small_venditti_heitmann_1997, title={Scanning electron microscopy analysis of fiber free toner agglomeration}, booktitle={1997 recycling symposium: Proceedings}, publisher={Chicago: Tappi Press}, author={Small, J. C. and Venditti, R. A. and Heitmann, J. A.}, year={1997}, pages={501–505} }
 @inbook{venditti_andrews_chang_heitmann_1997, place={Appleton, Wisc}, title={Stickies related research at North Carolina State University}, volume={1}, booktitle={Paper recycling challeng}, publisher={Doshi & Associates}, author={Venditti, R. A. and Andrews, E. K. and Chang, H.-M. and Heitmann, J. A.}, year={1997}, pages={45–49} }
 @misc{chang_wu_heitmann_1996, title={Deinking of xerographic printed wastepaper using long chain alcohol}, volume={5,500,082}, number={1996 Mar. 19}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Chang, H. M. and Wu, T. W. and Heitmann, J. A.}, year={1996} }
 @article{hubbe_chen_heitmann, title={Measurement and impact of charge: A practical guide}, volume={87}, number={11}, journal={Solutions! (Norcross, Ga.)}, author={Hubbe, M. A. and Chen, J. and Heitmann, J. A.}, pages={47–49} }
 @inproceedings{chen_hubbe_heitmann, title={Measurement of colloidal charge in the paper mill by streaming current}, booktitle={Proceedings, TAPPI Papermakers Conference, 2001}, publisher={Atlanta, GA: TAPPI Press}, author={Chen, J. and Hubbe, M. A. and Heitmann, J. A.} }
 @article{hubbe_chen_heitmann, title={Permeability reduction phenomena in packed beds, fiber mats, and wet webs of paper exposed to flow of liquids and suspensions: A review}, volume={4}, number={1}, journal={BioResources}, author={Hubbe, M. A. and Chen, H. and Heitmann, J. A.}, pages={405–451} }
 @article{hubbe_heitmann, title={Review of factors affecting the release of water from cellulosic fibers during paper manufacture}, volume={2}, number={3}, journal={BioResources}, author={Hubbe, M. A. and Heitmann, J. A.}, pages={500–533} }
 @article{cole_hubbe_heitmann, title={Water release from fractionated stock suspensions. Part 1 - Effects of the amounts and types of fiber fines}, volume={7}, number={7}, journal={TAPPI Journal}, author={Cole, C. A. and Hubbe, M. A. and Heitmann, J. A.}, pages={28–32} }
 @article{hubbe_heitmann_cole, title={Water release from fractionated stock suspensions. Part 2, Effects of consistency, flocculants, shear, and order of mixing}, volume={7}, number={8}, journal={TAPPI Journal}, author={Hubbe, M. A. and Heitmann, J. A. and Cole, C. A.}, pages={14–19} }