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The bacterial BcsA-B cellulose synthase synthesizes cellulose II when immobilized on nickel surfaces. To explore how lignin interacts with cellulose, lignin was polymerized either during or after cellulose formation from surface immobilized BcsA-B, leading to significant alterations in cellulose and lignin morphology. To facilitate lignin detection, polymerized coniferyl alcohol monolignols were detected by lignin autofluorescence. This compound was previously demonstrated as a suitable lignin monolignol exhibiting autofluorescence that enables lignin detection even at low concentrations. Cellulose and lignin coated nickel surfaces were studied under confocal microscopy, as well as by atomic force microscopy and X-ray diffractometry (XRD). As a consequence of simultaneous lignin and cellulose deposition on the surface, cellulose microfibril morphology was altered. XRD data indicated that cellulose crystal size was significantly decreased by polymerized lignin incorporation, suggesting that simultaneous lignin polymerization prevents the proper assembly of cellulose microfibrils. In contrast, polymerizing lignin after cellulose synthesis yielded a cellulose that was very similar in character to control (lignin-free) samples in terms of crystal morphology.

A morphological study of lignin-bound anthracite briquettes was carried out to understand the mechanisms that hold together anthracite fines and silicon grains at elevated temperatures and high abrasion conditions. Lab-scale briquettes were prepared from anthracite fines, lignin, collagen, silicon, and other additives; and then pyrolyzed at 800 °C, 1400 °C and 1600 °C under nitrogen atmosphere to simulate the conditions inside a foundry cupola. The pyrolyzed samples were analyzed by reflected light microscopy, electron microscopy and x-ray diffraction. These analyses gave information on the transformations that lignin-bound anthracite briquettes may undergo in a cupola furnace. Lignin and collagen melted and formed an amorphous carbon phase that linked anthracite and silicon grains. Silicon carbide (SiC) nanowires coated in silicon oxide were formed at 1400 °C, and at 1600 °C most of the silicon was converted to SiC. Silicon carbide nanowires filled the interstitial voids left by volatilization of lignin and collagen. These findings support the idea that lignin and collagen hold anthracite fines at low temperature regimes. Silicon carbide nanowires contribute to briquette strength at high temperature conditions, acting as reinforcing filler and prevent collapse of the lignin-collagen matrix surrounding the anthracite grains.

Columnar microfibrous thin films (μFTFs) of the polymer Parylene C with different microfiber inclination angles were fabricated using a physicochemical vapor deposition process whereby a collimated flux of hot monomers is obliquely directed towards a planar substrate. Each μFTF was then subjected to cyclic elastic loading in one of two orthogonal directions lying wholly in the substrate plane: either (i) normal or (ii) parallel to the morphologically significant plane of the μFTF. Dynamic storage and loss moduli were determined in the 1–80 Hz frequency range for temperatures between −40 °C and 125 °C. For all columnar μFTFs, the storage and loss moduli for normal loading did not exceed their counterparts for parallel loading. All columnar μFTFs were found to be softer than a bulk film of Parylene C. In both bulk and columnar forms, Parylene C was found to be rheologically not simple.

Anthracite briquettes were developed using mainly waste anthracite fines, plant byproducts of rice hulls and rice hull ash and silicon metal powder as an ecofriendly fuel and as an alternative to conventional coke used in a cupola furnace. Si metal powder reacts with anthracite to form SiC, which provides high mechanical strength to an anthracite briquette when it is exposed to a high temperature in the cupola furnace. Rice hull and rice hull ash, which are agricultural byproducts with high SiO2 content were investigated as partial substitutes for silicon as the former are inexpensive relative to silicon metal. The formation of SiC was investigated under different conditions using X-ray diffraction and transmission electron microscopy. In addition, unconfined compressive strength of the briquettes was measured when the rice hull or ash substituted Si powder partially or completely. When anthracite briquettes prepared with elemental Si powder and either rice hull ash or rice hull powder were pyrolyzed at 1400 °C for 2 h, SiC formed and the briquettes showed high mechanical strength in the range of 2000–4000 kPa, which is enough to keep their structural integrity in a cupola furnace.

Positively charged nitrogen functional groups were introduced onto the surface of granular activated carbon (GAC), and these increased perchlorate anion removal from drinking water sources. Nitrogen functionalization involved three treatment steps: (1) introducing oxygen groups onto the GAC, (2) incorporating nitrogen groups by thermal treatment in ammonia flow to replace O with N, and (3) quaternerizing pyridine-like groups to create positively charged pyridinium-like groups. Functionalized bituminous GAC provided 6 times more perchlorate removal than its predecessor, pristine bituminous GAC. The conversion of pyridine-like groups (after step 2) to pyridinium-like groups by quaternization (step 3) was confirmed by analysis of the XPS N 1s signals and surface charge analysis. Redox peaks, observed during cyclic voltammetry analysis of the functionalized GAC, evidenced that these nitrogen functional groups were electrochemically active, so that they sorbed perchlorate when they were oxidized, and then desorbed perchlorate when reduced. Moreover, after sorbing perchlorate onto pyridinium-GAC in RSSCTs, the GAC media could be regenerated by electrochemical reduction, and its capacity for perchlorate adsorption was mostly restored. This tailored functionality and redox regeneration of a relatively inexpensive media such as activated carbon could offer novel opportunity to the adsorption industry.

The manuscript initially failed to cite the work of Dr. Cong et al., which was the basis for this effort. We apologize for this error.

The polyaromatic structure of lignin has long been recognized as a key contributor to the rigidity of plant vascular tissues. Although lignin structure was once conceptualized as a highly networked, heterogeneous, high molecular weight polymer, recent studies have suggested a very different configuration may exist in planta. These findings, coupled with the increasing attention and interest in efficiently utilizing lignocellulosic materials for green materials and energy applications, have renewed interest in lignin chemistry. Here we focus on quinone methides (QMs)—key intermediates in lignin polymerization—that are quenched via reaction with cell-wall-available nucleophiles. Reactions with alcohol and uronic acid groups of hemicelluloses, for example, can lead to lignin-carbohydrate crosslinks. Our work is a first step toward exploring potential QM reactions with nucleophilic groups in cell wall proteins. We conducted a model compound study wherein the lignin model compound guaiacylglycerol-β-guaiacyl ether 1, was converted to its QM 2, then reacted with amino acids bearing nucleophilic side-groups. Yields for the QM-amino acid adducts ranged from quantitative in the case of QM-lysine 3, to zero (no reaction) in the cases of QM-threonine (Thr) 10 and QM-hydroxyproline (Hyp) 11. The structures of the QM-amino acid adducts were confirmed via 1D and 2D nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations, thereby extending the lignin NMR database to include amino acid crosslinks. Some of the QM-amino acid adducts formed both syn- and anti-isomers, whereas others favored only one isomer. Because the QM-Thr 10 and QM-Hyp 11 compounds could not be experimentally prepared under conditions described here but could potentially form in vivo, we used DFT to calculate their NMR shifts. Characterization of these model adducts extends the lignin NMR database to aid in the identification of lignin-protein linkages in more complex in vitro and in vivo systems, and may allow for the identification of such linkages in planta.

The present study characterized the products formed from the reaction of amino acids and in turn, proteins, with lignin resulting in cross-coupling. When added to reaction mixtures containing coniferyl alcohol, horseradish peroxidase and H2O2, three amino acids (Cys, Tyr, and Thr) are able to form adducts. The low molecular weight products were analyzed by HPLC and from each reaction mixture, one product was isolated and analyzed by LC/MS. LC/MS results are consistent with bond formation between the polar side-chain of these amino acids with Cα. These results are consistent with the cross-coupling of Cys, Tyr and Thr through a quinone methide intermediate. In addition to the free amino acids, it was found that the cross-coupling of proteins with protolignin through Cys or Tyr residues. The findings provide a mechanism by which proteins and lignin can cross-couple in the plant cell wall.

The current study uses nuclear magnetic resonance, Fourier-transform infrared spectroscopy and Raman spectroscopy to investigate the evolution of refined softwood and hardwood lignins under various pyrolytic exposures. Little chemical change occurred at pyrolysis temperatures of 250 and 300 °C, whereas significant mass loss and chemical change was observed at 400 and 500 °C. These losses were mainly attributed to evolution of methoxyl, hydroxyl, and propyl groups. Mass loss plateaued following pyrolysis at 500 °C, but rearrangements continued to occur at higher temperatures, resulting in char that became increasingly polyaromatic in nature. Following brief pyrolytic exposures at 500 and 600 °C, the refined hardwood and softwood lignins yielded coal-like products. Lignin pyrolyzed at higher temperatures yielded chars with greater order, similar in composition to coke. These coal and coke-like products are called “lignin-based carbon” (LBC). The polyaromatic nature of the LBC after high temperature pyrolysis was perceived as the result of radical formation and recombination, leading to fused aromatic structures, which occurs more readily at higher temperatures.

A novel method has been developed for anchoring quaternary ammonium/epoxide-forming compounds (QAEs) within bituminous based granular activated carbons (GACs). This modified GAC was then used to remove perchlorate from groundwater. The effect of the preparation temperature (T), solution pH (pH) and the dry mass ratio of QAE-to-GAC (R) over the perchlorate adsorption capacity (Qe) were studied by the Response Surface Methodology. The combined effects of these variables were fitted to a quadratic model to determine the more favorable preparation protocol for perchlorate removal. Statistical analysis revealed that: (1) the interaction of T and pH incurred the most effect on Qe; and (2) two of the more favorable preparation protocols became apparent: one was at 75 °C, pH 11 and R of 1.73 g QAE/g GAC (U17), the other was at 35 °C, pH 14 and R of 4.00 g QAE/g GAC (U2). Rapid small scale column tests were further employed to evaluate the performance of the QAE-anchored GACs for perchlorate removal. U17 and U2 exhibited 18–20 times longer bed life (BV) to 6 ppb breakthrough than did the Pristine GAC (900 BV), when processing groundwater that had been spiked with 30–35 ppb perchlorate. This indicated the statistical method enhanced GAC’s perchlorate removal efficiency.

A novel method has been developed for anchoring quaternary ammonium/epoxide-forming compounds (QAE) within bituminous and wood based granular activated carbons (GACs). This QAE-anchored GAC was then used to enhance perchlorate removal from perchlorate-spiked natural groundwater. Specifically, for the bituminous based carbon, while processing natural groundwater that had been spiked with 30–35 ppb perchlorate, and passing this water through rapid small scale column tests, the bed volumes (BV) to 2 ppb perchlorate breakthrough increased from 870 BV for pristine GAC up to 21,000 BV for the corresponding GAC that had been pre-anchored with QUAB360 (360 Da). However, the wood based GAC that had been anchored with this QUAB360 achieved only 3000 BV. None of the QAE leached out of these GACs during the column tests. The bituminous GAC that had been pre-anchored with QAE hosted more positive surface charge at pH 7.5 than did the wood based QAE–GAC. Per X-ray photoelectron spectroscopy, the QAE anchored into the GACs increased their N-content by 1–1.3%. By means of multiple analyses, the authors surmised that the active quaternary ammonium sites within the tailored bituminous-based GAC were more exposed and thus more accessible for perchlorate adsorption than those within wood based GAC.

Lignin that had been extracted from Kraft black liquor was investigated as a fusing binder in briquetted anthracite fines for a foundry coke substitute. Cupola “heat zone” pyrolytic temperatures of 300–1550 °C were appraised, with the focus on 900 °C. Briquettes with favorable strength were made with 86–92% anthracite fines, 2.3–8.6% lignin, 4.5% silicon metal powder, and 0.9% hydrolyzed collagen (denatured collagen) by mass. Briquettes were pyrolyzed under a nitrogen atmosphere or a starved air condition to simulate a cupola pyrolytic heat zone, and then crushed after this pyrolysis so as to discern their unconfined compressive (UC) strength. These tests mimicked key features of the crushing load that coke endures in a cupola. After 30 min of 900 °C pyrolysis, UC strength reached 2200–3000 kPa (320–440 psi), when these briquettes contained 4.5% softwood lignin or 2.3% hardwood lignin. With ⩾6.5% hardwood lignin, the UC strength after 900 °C pyrolysis reached 6000–6500 kPa. When no lignin was incorporated into the briquette, the UC strength after 900 °C pyrolysis was a mere 200 kPa. Denatured collagen quantity affected lignin heat zone strength, despite by itself losing strength around 300 °C: with 4.5% lignin present, 1.8% denatured collagen doubled the strength of 0.45% denatured collagen briquettes. Adding tannic acid to the briquettes greatly increased the UC strength as well. Lignin provided strength up to 1400 °C. Moreover above 1100 °C, silicon carbide nanowires greatly enhanced UC strength relative to lignin alone. Briquettes with lignin gained UC strength very quickly when flash pyrolyzed to 900 °C, which is important in the cupola. The results herein showed that the bindered briquettes burned at an equal rate as did coke when these were burned at 1100 °C in air. The briquettes also contained an energy density that was 38% higher by volume than that of coke. Harnessing these high temperature pyrolytic lignin fusing reactions creates a valuable foundry coke substitute for the future, as well as large scale applications for otherwise underutilized industrial streams of lignin.

Metalcasting within the United States aims to meet ever-more stringent environmental standards as new process technologies are developed. Conventional foundry core binders are responsible for up to 70% of a foundry's volatile organic compound (VOC) emissions. New core binder technologies are essential for environmental sustainability within foundries. Herein, conventional and novel foundry core binders were appraised using thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), hot distortion testing (HDT), and (Pilot-scale) molten iron erosion tests. Inherently, these tests cannot replace full-scale casting trials to evaluate binder effectiveness, however, these tests were performed to more fully elucidate binder properties that might cause casting defects or other unwanted behaviors at high temperatures. During each of these lab protocols, the combination of collagen plus alkali silicate as binders exhibited properties that matched or exceeded those of conventional phenolic urethane. Also, in iron erosion testing, the collagen/alkali silicate binder exhibited the same low erosion as conventional phenolic urethane. In hot distortion testing, the collagen–alkali silicate binder exhibited longer resistance to thermal bending, and comparable thermal flexibility to conventional phenolic urethane.

Using subcellular fractionation and Western blot methods, we have shown that AcsD, one of the proteins encoded by the Acetobacter cellulose synthase (acs) operon, is localized in the periplasmic region of the cell. AcsD protein was heterologously expressed in Escherichia coli and purified using histidine tag affinity methods. The purified protein was used to obtain rabbit polyclonal antibodies. The purity of the subcellular fractions was assessed by marker enzyme assays.

Eight North American resin suppliers, representing 100 percent of the polymeric diphenylmethane diisocyanate (pMDI) market and >95 percent of the urea-formaldehyde (UF) market for interior wood composite panels (IWCPs), participated in an exploratory phone survey conducted in July and August 2008 that was designed to better understand their product positioning and “green” resin strategies. These eight firms were identified as the largest suppliers to the IWCP industry, which includes particleboard, medium density fiberboard, hardwood plywood, and hardboard. In 2007, the IWCP resin industry was highly concentrated and dominated by UF resins. Resin suppliers rated research and development work and technical support as the most important competitive advantage factors they used. Moreover, resin suppliers perceived the following product and service attributes to have the greatest importance to their IWCP customers: low formaldehyde emissions from finished panels (4.8 of 5), fast resolution of customer complain...

The effect of varying proportions of maleic anhydride polypropylene (MAPP) on the physical and mechanical properties of polymeric diphenylmethane diisocyanate (pMDI)-bonded oriented strand board panels was investigated. Additionally, two forms of MAPP (powder and emulsion) were used to determine the effect of MAPP type on panel properties. Panels were produced by combining southern yellow pine (Pinus spp.) flakes with 4 percent pMDI binder and 0, 1.5, 3, 4.5, or 6 percent powdered or emulsified MAPP. Addition of emulsified MAPP decreased panel mechanical properties regardless of addition level. Powdered MAPP had a negligible effect on panel modulus of elasticity and only produced significant decreases in panel modulus of rupture and internal bond strength at the highest addition level (6%). Emulsified MAPP effected greater reductions in panel mechanical properties relative to powdered MAPP. Increasing levels of emulsified MAPP caused undesirable increases in both 24-hour water absorption and thickness swelling. Powdered MAPP did not provide a significant improvement over control panels in water absorption and thickness swell tests. Addition of either powdered or emulsified MAPP appeared to have a negligible effect on panel permeance.

Lignin degradation is of critical importance in biomass utilization of woody plants, because the presence of lignin limits hydrolytic enzyme access to cellulose and hemicellulose. To date, strategies for lignin removal have ranged from treatment with lignin-degrading fungi to genetic manipulations that reduce lignin content or modify monolignol composition. However, reducing lignin content without compromising tree fitness can be difficult. An alternate approach to modify lignin composition by introducing in situ peptide cross-links is reported here. The hypothesis was that introducing in situ peptide cross-links would not change overall lignin content or distribution in the cell wall, yet should render the lignin more susceptible to protease digestion. To test this, a transgene encoding a high tyrosine-content peptide was designed to express in lignifying tissues of hybrid poplar. Relative to wildtypes, the transgenics had no change in total lignin content or overall plant morphology, although the wood in a number of lines had reduced storage modulus. As predicted, a number of transgenic lines were more susceptible to protease digestion than wildtypes, resulting in a higher polysaccharide release from the lignocellulose complexes. Although preliminary, these results suggest that this may be a viable means to facilitate lignin removal and potentially advance the utilization of woody biomass as a biofuel feedstock.

Three poly[(vinyl acetate)-co-N-methylolacrylamide] (VAc–NMA) latex adhesives were synthesized, each containing the same total amount of NMA. In each of the three co-polymerizations, the NMA was fed into the reactor according to a unique feed profile. NMA distribution in the latexes, as determined via both 13C and 15N variable temperature solution nuclear magnetic resonance (NMR) spectroscopy, differed among the three adhesives. When NMA monomer was added via injections (latex I), predominantly surface-NMA (62.7%) was detected, with significant amounts of water-phase NMA (20.8%) and core NMA (16.5%). Delayed NMA injections (latex DI) led to a very high proportion of surface NMA (82.3%) with less core (10.6%) and water-phase NMA (7.1%). A continuous feed of NMA (latex C) gave predominantly core NMA (84.7%), some surface NMA (13.4%) and very little water-phase NMA (1.9%). NMA distribution findings from 15N-NMR and 13C-NMR analyses were consistent.

Fracture mechanics, scanning electron microscopy (SEM), and fluorescence microscopy were used to evaluate the performance and durability of three poly[(vinyl acetate)-co-N-methylolacrylamide] latex adhesives. Results from mode I fracture tests of wood-adhesive double cantilever beam specimens indicated that in the absence of accelerated aging conditions, the three adhesives performed similarly. After the samples were exposed to either boil or vacuum soak accelerated aging, differences among the adhesives emerged. Latex I (N-methylolacrylamide (NMA) injected throughout the polymerization) exhibited enhanced performance after weathering, whereas the performance of latexes DI (delayed injections of NMA) and C (continuous addition of NMA) either remained unchanged or declined after weathering. Fluorescence microscopy of wood-adhesive bond lines and SEM of latex films after accelerated aging exposures both indicated that latex I showed a unique resistance to the aging conditions. Relatively high proportions of water-phase NMA correlate with improved latex durability.

The penetration and performance of polymeric diphenylmethane diisocyanate (pMDI) wood binder was investigated according to three factors: substrate species (aspen, yellow-poplar, or southern yellow pine); anatomical bonding plane (radial or tangential); and moisture content (0%, 5%, or 12%). Compression shear block tests and fluorescence microscopy were used to examine bond performance and resin penetration. Statistically, each of the aforementioned factors impacted results. As moisture content increased, observed bond strengths and wood failure increased. Bond formation did not occur when the substrates were equilibrated to 0% moisture content, except for the radial bonding surfaces of pine, which did adhere. At 5 and 12% moisture contents, tangential bonding surfaces out-performed radial bonding surfaces. In terms of resin penetration, moisture content was clearly the most important variable. Little penetration was observed at 0% moisture content, while extensive resin penetration was observed at elevated moisture contents. Pine was the only wood species to exhibit resin flow through radial cells, possibly explaining the enhanced resin penetration depths observed in pine samples.

Elastic cyclic loading of ~110 µm-thick Parylene C thin films comprising parallel slanted microfibers was performed in the frequency range 5–200 Hz, to determine the dependences of their storage and loss moduli on the temperature and the frequency. The glass-transition temperature was identified as about 65 °C from the temperature-maximum of the loss modulus. A low-frequency peak (at 115–135 Hz) in the variation of the loss modulus is due to the resonance of an individual microfiber loaded by the remaining microfibers in the film.

Labeled derivatives of N-methylolacrylamide (NMA) including 1 5 N-NMA, 1 3 C-NMA, and 1 3 C, 1 5 N-NMA were synthesized and purified. A required chemical precursor, 1 5 N-acrylamide, was also prepared. Reported methods forsynthesizing unlabeled analogs are noted, and modifications to these methods for achieving the labeled materials are specified. Monomers were examined via 1 H, 1 3 C, and 1 5 N nuclear magnetic resonance (NMR) spectroscopy. Peak assignments and coupling constants are reported for each compound. To our knowledge, this is the first reported publication on the preparation and characterization of 1 3 C-NMA, 1 5 N-NMA, 1 3 C, 1 5 N-NMA, and 1 5 N-acrylamide.

The work presented here investigates the cross-linking of various nucleophilic amino acids with lignin under aqueous conditions, thus providing insight as to which amino acids might cross-link with lignin in planta. Lignin dehydrogenation polymer (DHP) was prepared in aqueous solutions that contained tripeptides with the general structure XGG, where X represents an amino acid with a nucleophilic side chain. Fourier-transform infrared spectroscopy and energy dispersive X-ray spectroscopy showed that peptides containing cysteine and tyrosine were incorporated into the DHP to form DHP-CGG and DHP-YGG adducts, whereas peptides containing other nucleophilic amino acids were not incorporated. Scanning electron microscopy showed that the physical morphology of DHP was altered by the presence of peptides in the aqueous solution, regardless of peptide incorporation into the DHP. Nuclear magnetic resonance (NMR) spectroscopy showed that cysteine-containing peptide cross-linked with lignin at the lignin α-position, whereas in the case of the lignin-tyrosine adduct the exact cross-linking pathway could not be determined. This is the first study to use NMR to confirm cross-linking between lignin and peptides under biomimetic conditions. The results of this study may indicate the potential for lignin-protein linkage formation in planta, particularly between lignin and cysteine- and/or tyrosine-rich proteins.

Our study has identified pathways and gene candidates that may be associated with the greater flexibility and digestibility of the poplar cell walls. With the goal of facilitating lignin removal during the utilization of woody biomass as a biofuel feedstock, we previously transformed a hybrid poplar clone with a partial cDNA sequence encoding a tyrosine- and hydroxyproline-rich glycoprotein from parsley. A number of the transgenic lines released more polysaccharides following protease digestion and were more flexible than wild-type plants, but otherwise normal in phenotype. Here, we report that overexpression of the tyrosine-rich peptide encoding sequence in these transgenic poplar plants did not significantly alter total lignin quantity or quality (S/G lignin ratio), five- and six-carbon sugar contents, growth rate, or susceptibility to a major poplar fungal pathogen, Septoria musiva. Whole-genome microarray analysis revealed a total of 411 differentially expressed transcripts in transgenic lines, all with decreased transcript abundance relative to wild-type plants. Their corresponding genes were overrepresented in functional categories such as secondary metabolism, amino acid metabolism, and energy metabolism. Transcript abundance was decreased primarily for five types of genes encoding proteins involved in cell-wall organization and in lignin biosynthesis. The expression of a subset of 19 of the differentially regulated genes by qRT-PCR validated the microarray results. Our study has identified pathways and gene candidates that may be the underlying cause for the enhanced flexibility and digestibility of the stems of poplar plants expressing the TYR transgene.