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Water is one of the principal constituents by mass of living plant cell walls. However, its role and interactions with secondary cell wall polysaccharides and the impact of dehydration and subsequent rehydration on the molecular architecture are still to be elucidated. This work combines multidimensional solid-state 13C magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) with molecular dynamics modeling to decipher the role of water in the molecular architecture of softwood secondary cell walls. The proximities between all main polymers, their molecular conformations, and interaction energies are compared in never-dried, oven-dried, and rehydrated states. Water is shown to play a critical role at the hemicellulose–cellulose interface. After significant molecular shrinkage caused by dehydration, the original molecular conformation is not fully recovered after rehydration. The changes include xylan becoming more closely and irreversibly associated with cellulose and some mannan becoming more mobile and changing conformation. These irreversible nanostructural changes provide a basis for explaining and improving the properties of wood-based materials.

A chemometric approach is presented to differentiate and segregate bark biomass variability by proportionating the chemical functionality of components based on solid state NMR. Bark can vary from ...

Six tree species were examined using 1H NMR spectroscopy of sap extracted by supercritical CO2. A metabolomic approach was developed to evaluate the sap extracted from sapwood of Norway spruce (Picea abies), Sitka spruce (Picea sitchensis), radiata pine (Pinus radiata), macrocarpa (Cupressus macrocarpa), and two Eucalyptus species-shining gum and mountain ash (Eucalyptus nitens and Eucalyptus regnans. The sap extraction patterns in the different species were visualised using 1H magnetic resonance imaging. In softwoods with distinct annual rings, water was first removed from the latewood bands, and then gradually from the earlywood bands. In the case of the hardwood species an almost random water redistribution, rather than water expulsion, was observed. Analysis of the principal component analysis loading plots showed that the significant differences in the sap between each species were due to the carbohydrate region. Key discriminators were identified as pinitol, sucrose, glucose, and fructose.

Cellulose possesses considerable potential for a wide range of sustainable applications. Nanocellulose-based material properties are primarily dependent on the structural surface characteristics of its crystalline planes. Experimental measurements of the affinity of crystalline nanocellulose surfaces with water are scarce and challenging to obtain. Therefore, the relative hydrophilicity of different cellulose allomorphs crystalline planes is often inferred from qualitative assessments of their surface and the exposition of polar groups to the solvent. This work investigates the relative hydrophilicity of cellulose surfaces using molecular dynamics simulations. The behavior of a water droplet laid on different crystal planes was used to determine their relative hydrophilicity. The water molecules fully spread onto highly hydrophilic surfaces. However, a water droplet placed on less hydrophilic surfaces equilibrates as an oblate spheroidal cap allowing the measurement of a contact angle. The results indicate that the Iα (010), Iα (11̅0), Iβ (010), and Iβ (110) faces, as well as the faces of human-made celluloses II and III_I (100), (11̅0), (010), and (110) are all highly hydrophilic. They all have a contact angle value inferior to 11°. Not unexpectedly, the Iα (001) and Iβ (100) surfaces are less hydrophilic with contact angles of 48 and 34°, respectively. However, the Iβ (11̅0) plane, often referred to as a hydrophilic surface, forms a contact angle of about 32°. The results are rationalized in terms of structure, exposure of hydroxyl groups to the solvent, and degree of cellulose-cellulose versus cellulose-water hydrogen bonds on each face. The simulations also show that the surface oxidation degree tunes the surface hydrophilicity in a nonlinear manner due to cooperative effects involving water-cellulose interactions. Our study helps us to understand how the degree of hydrophilicity of cellulose emerges from specific structural features of each crystalline surface.

Douglas-fir (Pseudotsuga menziesii) has distinctly colored heartwood as a result of extractive deposition during heartwood formation. This is known to affect natural durability and treatability with preservatives, as well as other types of wood modification involving infiltration with chemicals. The distribution of extractives in sapwood and heartwood of Douglas-fir was studied using fluorescence microscopy. Several different types of extractive including flavonoids, resin acids, and tannins were localized to heartwood cell walls, resin canals, and rays, using autofluorescence or staining of flavonoids with Naturstoff A reagent. Extractives were found to infiltrate the cell walls of heartwood tracheids and were also present to a lesser extent in sapwood tracheid cell walls, especially in regions adjacent to the resin canals. Förster resonance energy transfer measurements showed that the accessibility of lignin lining cell wall micropores to rhodamine dye was reduced by about 50%, probably as a result of cell wall-bound tannin-like materials which accumulate in heartwood relative to sapwood, and are responsible for the orange color of the heartwood. These results indicate that micro-distribution of heartwood extractives affects cell wall porosity which is reduced by the accumulation of heartwood extractives in softwood tracheid cell walls.

RATIONALE A combination of stable carbon (δ13 C) and hydrogen (δ2 H) isotope ratios and carbon content (% C) was evaluated as a rapid, low-cost analytical approach to authenticate bioplastics, complementing existing radiocarbon (14 C) and Fourier transform infrared (FTIR) analytical methods. METHODS Petroleum- and bio-based precursor materials and in-market plastics were analysed and their δ13 C, δ2 H and % C values were used to establish isotope criteria to evaluate plastic claims, and the source and biocontent of the samples. 14 C was used to confirm the findings of the isotope approach and FTIR analysis was used to vertify the plastic type of the in-market plastics. RESULTS Distinctive carbon and hydrogen stable isotope ratios were found for authentic bio-based and petroleum-based precursor plastics, and it was possible to classify in-market plastics according to their source materials (petroleum, C3, C4, and mixed sources). An estimation of C4 biocontent was possible from a C4-petroleum isotope mixing model using δ13 C which was well correlated (R2 = 0.98) to 14 C. It was not possible to establish a C3-petroleum isotope mixing model due to δ13 C isotopic overlap with petroleum plastics; however, the addition of δ2 H and % C was useful to evaluate if petroleum-bioplastic mixes contained C3 bioplastics, and PLS-DA modelling reliably clustered each plastic type. CONCLUSIONS A combined dual stable isotope and carbon content approach was found to rapidly and accurately identify C3 and C4 bio-based products from their petroleum counterparts, and identify instances of petroleum and bio-based mixes frequently found in mislabelled bioplastics. Out of 37 in-market products labelled as bioplastic, 19 were found to contain varying amounts of petroleum-based plastic and did not meet their bio-based claims.

A knowledge of the mobilities of the polysaccharides or parts of polysaccharides in a cell-wall preparation provides information about possible molecular interactions among the polysaccharides in the cell wall and the relative locations of polysaccharides within the cell wall. A number of solid-state

The porosity of wood cell walls is of interest for both understanding xylem functionality and from a wood materials perspective. The movement of water in xylem generally occurs through the macroporous networks formed in softwood by bordered pits and in hardwood by the intervessel pits and open conduits created by vessels and perforation plates. In some situations, such as cavitated xylem, water can only move through the micropores that occur in lignified tracheid and fiber cell walls; however, these micropore networks are poorly understood. Here, we used molecular microscopy analysis of radiata pine (Pinus radiata) and red beech (Nothofagus fusca) to determine the distribution of micropores in the secondary walls and middle lamellae of tracheids and fibers in relation to cell wall composition. Using two different types of probe, we identified a greater porosity of secondary cell walls and a reduced porosity of the middle lamella. Areas of reduced porosity were observed in the outer regions of the secondary cell wall of both tracheids and fibers that appear unrelated to lignification or the distribution of cellulose, mannan, and xylan. Hardwood fiber cell walls were less lignified than those of softwood tracheids and showed greater accessibility to porosity probes. Vessel cell walls were comparable to those of fibers in terms of both porosity and lignification. Lignification is probably the primary determinant of cell wall porosity in xylem. The highly lignified middle lamella, and lumen surface, act as a barrier to probe movement and, therefore, water movement in both softwood and hardwood.

Unlike a traditional review, this article does not summarise and discuss scientific progress in terms of traditional focus topics such as upstream processes or conversion and downstream processes, but instead provides examples proving that “Yes, we can make money from lignin and other bio-based resources”. The nine success stories from Scion's research are differentiated by the size of the product from designing trees with customised lignin and modifying wood dried by supercritical processing to bioaromatics from lignin hydrogenolysis, the scale of the product – from wood fibre plastic composites at commercial scale and lignin-rich bioadhesives to bio-based materials for 3D printing and the value of the product(s) – from lignin-based nanofibres and supercritical extraction of chemicals and compounds to utilising biomass side streams.

Summary: This protocol describes the application of breath testing and ex vivo fermentations to study the association between breath methane and the composition and functionality of the gut microbiome. The protocol provides a useful systems biology approach for studying the gut microbiome in humans, which combines standardized methods in human breath testing and fecal sampling. The model described is accessible and easy to repeat, but its relative simplicity means that it can deviate from human physiological conditions.

The migration from the concept of waste streams to untapped side streams has meant that by-products from industrial processes are being investigated as sustainable resources. As a side stream containing cellulosic fibre, the influence of integrating farm dairy effluent (FDE) in polylactic acid (PLA) was investigated and compared with wood sander dust (SD). The mechanical and thermal properties of injection moulded specimens were evaluated as a function of filler type. The investigation indicated that FDE had similar density to SD but a lower stiffness attributed to the presence of proteins and the lesser amount of cellulose. The Young’s moduli of the FDE composites were higher than the neat PLA, however, the tensile strength generally decreased but remained comparable to those filled with SD. Thermo-mechanical analysis indicated an improvement in the storage modulus of all composites containing 40 wt% of either filler above the glass transition temperature of PLA. Tensile testing of specimens that were exposed to accelerated weathering indicated a faster decrease in properties for the FDE composites compared to those filled with SD. The FDE composites degraded at least twice as fast as neat PLA and SD composites, which was tentatively attributed to the acids (e.g. fatty and amino-acids) contained in FDE and not present in SD. These findings revealed that using extrusion and injection moulding processes, FDE has potential as a composite filler from an improved stiffness and UV accelerated degradation perspectives.

Proton magnetic resonance (MR) imaging at 300 MHz was used to characterise the dewatering of Pinus radiata sapwood. The sapwood was immersed in CO 2 that was cycled at temperatures greater than 31 °C between gas (0.1–6 MPa) and supercritical fluid (15–20 MPa) phase. A combination of FLASH and RARE pulse sequences were used to highlight differences in T 2 *( H ) and T 2 ( H ) relaxation. It was observed that CO 2 entered into the green sapwood via air or water vapour-filled cells in the latewood and then diffused into earlywood cells adjacent to the pith side of the latewood bands. The dissolved CO 2 reduced the surface tension of water which facilitated the expulsion of sap. As the pressure was released, and CO 2 bubbles formed and expanded, the sap flowed tangentially towards the surfaces. This accounted, in part, for the observed independence of sample size on the supercritical CO 2 dewatering process.

We demonstrate the use of tetraethylorthosilicate (TEOS) as a silica precursor for water barrier poly(styrene-butadiene) latex dispersion coating applications. The TEOS is adsorbed at the surface interface by the latex particles in the aqueous dispersion due to the hydrophobic nature of the surface and the TEOS. It then undergoes hydrolysis and condensation to the silica phase in the interstitial sites in the partially dry close-packed polymer structure. The fully cured film exhibits a greater degree of coalescence than films prepared from the unmodified latex binder. Large discrete silica particles are not formed within the cured film; rather the films contain homogenous silica dispersion with a probable particle size no larger than 10 nm. This higher degree of coalescence results in improvements in water vapour barrier performance from 121 – 20 g m−2 d−1, with direct water barrier performance (Cobb 120 s) improving from 25 to

Pretreating lignocellulosic biomass with certain ionic liquids results in structural and chemical changes that make the biomass more digestible by enzymes. In this study, pine wood was pretreated with 1-ethyl-3-methylimidazolium chloride/acetate ([C2 mim]Cl and [C2 mim][OAc]) at different temperatures to investigate the relative importance of substrate features, such as accessible surface area, cellulose crystallinity, and lignin content, on enzymatic digestibility. The ionic liquid pretreatments resulted in glucan conversions ranging from 23% to 84% on saccharification of the substrates, with [C2 mim][OAc] being more effective than [C2 mim]Cl. The pretreatments resulted in no delignification of the wood, some loss of cellulose crystallinity under certain conditions, and varying levels of increased surface area. Enzymatic digestibility closely correlated with accessible surface area and porosity measurements obtained using Simons' staining and thermoporosimetry techniques. Increased accessible surface area was identified as the principal structural feature responsible for the improved enzymatic digestibility.

A novel approach to nanoscale detection of cell wall porosity using confocal fluorescence microscopy is described. Infiltration of cell walls with a range of nitrophenyl-substituted carbohydrates of different molecular weights was assessed by measuring changes in the intensity of lignin fluorescence, in response to the quenching effect of the 4-nitrophenyl group. The following carbohydrates were used in order of increasing molecular weight; 4-nitrophenyl β-D-glucopyrano-side (monosaccharide), 4-nitrophenyl β-D-lactopyranoside (disaccharide), 2-chloro-4-nitrophenyl β-D-maltotrioside (trisaccharide), and 4-nitrophenyl α-D-maltopentaoside (pentasaccharide). This technique was used to compare cell wall porosity in wood which had been dewatered to 40% moisture content using supercritical CO2, where cell walls remain fully hydrated, with kiln dried wood equilibrated to 12% moisture content. Infiltration of cell walls as measured by fluorescence quenching, was found to decrease with increasing molecular weight, with the pentasaccharide being significantly excluded compared to the monosaccharide. Porosity experiments were performed on blocks and sections to assess differences in cell wall accessibility. Dewatered and kiln dried wood infiltrated as blocks showed similar results, but greater infiltration was achieved by using sections, indicating that not all pores were easily accessible by infiltration from the lumen surface. In wood blocks infiltrated with 4-nitrophenyl α-D-maltopentaoside, quenching of the secondary wall was quite variable, especially in kiln dried wood, indicating limited connectivity of pores accessible from the lumen surface.

Organic phosphorus (P) can play a role in in-stream productivity (e.g., periphyton or macrophyte growth), but little is known of the largest likely source of organic P—bed sediment. A survey was conducted of 76 bed sediment samples of rivers within the New Zealand National River Water Quality Network in an effort to determine the concentration and form of organic P species, and variation according to catchment and sediment characteristics or classifications used to characterise anthropogenic P inputs (e.g., as baseline [viz. reference] or impact sites) and therefore likely in-stream productivity. Sediments were analysed for a range of physiochemical properties. NaOH-EDTA extracts were analysed by 31P nuclear magnetic resonance spectroscopy (31P NMR), which isolated orthophosphate from other P species including orthophosphate monoesters, orthophosphate diesters and pyrophosphate. More P was extracted from sediments at impact compared to baseline sites, while the proportion of organic P increased where microbial processing (as reflected by site elevation) decreased. Analysis by 31P NMR of sediments showed they contained fewer and less-enriched forms of organic P than profiles of typical lake sediments or soils (e.g., no phosphonates or polyphosphates). This was hypothesised to reflect either low P inputs via catchment runoff, or efficient utilisation due to strong P limitation. Some evidence was found of changes in the distribution and form of organic P species in relation to anthropogenic activity and sediment processes. However, organic P concentrations were small and only represented a single sampling. Hence, additional work needs to examine if these changes relate to changes in in-stream productivity over time.

Carbon-13 chemical-shift imaging (CSI) was used to study the distribution of CO 2 in green pine sapwood that was partially dewatered by a process in which CO 2 was cycled between the supercritical fluid and gas phases. Proton magnetic resonance imaging (MRI) was used to characterise the corresponding distribution of water. The CSI experiment showed strongest signals from cells with weakest proton MRI signals. This was consistent with a mechanism in which latewood bands provide pathways for supercritical CO 2 to penetrate into the interior of a specimen. Supercritical CO 2 also penetrated earlywood exposed on surfaces of the specimen.

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette.

Biologically-resistant carbon (C) comprises the bulk of C in most soils and is often estimated from chemical separation of a soil organic matter (SOM) fraction that is not hydrolysed by strong acid, and exhibits an older radiocarbon age and slower turnover than the whole SOM. Here we examine the effects of acid hydrolysis – the method used to separate the nonhydrolysable C – on the quantity, structure and isotopic makeup of C in pure model carbohydrates and those contained in senescent maize that resemble C inputs to SOM. We demonstrate that significant alterations occur during hydrolysis resulting in C mass losses (up to 75% preferential loss of 13C) and de novo synthesis of nonhydrolysable, 13C-depleted material dominated by aromatic > alkyl > carbonyl moieties. We infer that similar losses, and transformations of 14C, would partly explain the greater ages attributed to the chemically resistant C, seriously impairing the use of acid hydrolysis to identify this pool of SOM and that de novo synthesis during hydrolysis has obfuscated the true chemical nature of the nonhydrolysable fraction of SOM.

The impact on the chemical composition and changes to the cellulose crystallites in Pinus radiata wood chips under light ( ca. 230 °C), mild ( ca. 260 °C), and severe (290+ °C) torrefaction temperatures at a range of times was examined by solid state 13 C CP-MAS and Dipolar Dephased NMR spectroscopy, TGA, and synchrotron based X-ray diffraction. Results indicated the decomposition of hemicelluloses into furfurals at the lowest temperature with little modification to the lignin or cellulose. De-polymerisation of lignin and cellulose was observed as torrefaction severity increased. The increased hydrophobicity under light and mild torrefaction severity was attributed to a combination of thermo-chemical modifications to hemicelluloses and lignin, along with cellulose crystal lattice changes. The observed decrease in hydrophobicity under severe torrefaction conditions was attributed to the degradation of cellulose crystallites.

Plant cell walls form an organic complex composite material that fulfils various functions. The hierarchical structure of this material is generated from the integration of its elementary components. This review provides an overview of wood as a composite material followed by its deconstruction into fibres that can then be incorporated into biobased composites. Firstly, the fibres are defined, and their various origins are discussed. Then, the organisation of cell walls and their components are described. The emphasis is on the molecular interactions of the cellulose microfibrils, lignin and hemicelluloses in planta. Hemicelluloses of diverse species and cell walls are described. Details of their organisation in the primary cell wall are provided, as understanding of the role of hemicellulose has recently evolved and is likely to affect our perception and future study of their secondary cell wall homologs. The importance of the presence of water on wood mechanical properties is also discussed. These sections provide the basis for understanding the molecular arrangements and interactions of the components and how they influence changes in fibre properties once isolated. A range of pulping processes can be used to individualise wood fibres, but these can cause damage to the fibres. Therefore, issues relating to fibre production are discussed along with the dispersion of wood fibres during extrusion. The final section explores various ways to improve fibres obtained from wood.

Purpose Heavy winter mulch treatments are commonly practiced in Phyllostachys praecox bamboo forests to increase bamboo shoot production in early spring in subtropical China. The aim of this study was to quantify the chemical behaviour of the mulching materials and the immediate response of soil carbon (C) to the heavy winter mulch treatments.

Reaction of an aqueous solution of osmium tetroxide with the chitosan polymer model, the oligomer tetradeca(β(1→4)2-amino-2-deoxyglucopyranose)-β(2→5)mannitol, afforded a brown solid, the structure of which was proposed to contain osmium imido groups, −N˭Os. The product showed a new, distinct absorption band at 850 cm−1 in the FTIR spectrum, while the 13C CP-MAS NMR spectrum showed a lower signal relative intensity ratio for C2:C3/5 compared with that in the NMR spectrum of the starting oligosaccharide due to a downfield shift of C2 where allylic to the -N˭Os bond. Results from quantum chemical calculations were used to compare computed properties of the previously described “osmium tetroxide-chitosan complex” in which osmium tetroxide was coordinated to chitosan amino ligands with single dative N→Os bonds, and the product prepared in this study, proposed to have covalently-bonded imido bonds between osmium and nitrogen. The consequences of multiple bonding of two chitosan N to the Os atom in the 5d 3 6s ...

Roger’s nature, and he himself freely admitted to being a pedant, meant that he was destined to excel in his chosen fields of interest. In 1966 Roger had an idea that he would like to pursue a career in Science. In New Zealand in the 1960s this meant either becoming staff at a University or joining the Department of Scientific and Industrial Research (DSIR). Roger cold-called Ian Walker the director of the DSIR and enquired what he would need to do to be a scientist? The answer saw Roger enrolled at the University of Canterbury (NZ) where he obtained a BSc (Hons) in quantum chemistry and in the process learned to use the powerful multi-kilobyte computers of the time. This instilled in Roger a love of computational chemistry and mathematical modelling of data that became such a large part of Roger’s final research years. From 1970 until 1973 Roger was employed as a scientist in the physical chemistry division of the DSIR. His section was responsible for X-ray diffraction and spectroscopic techniques such as nuclear magnetic resonance. Roger was involved in some of the initial work on spin–lattice relaxation of liquid crystal systems and the effect of gradients on NMR experiments (McLachlan et al. 1971, 1973) that thus became a mainstay technique over Roger’s long research career. In 1973 Roger was awarded an NRAC Fellowship to carry out a PhD at the University of East Anglia (UK) in the area of theoretical and practical carbon, phosphorus and silicon NMR under Robin Harris (Harris and Newman 1977; Harris et al. 1984). He returned to DSIR to become the Spectroscopy Section Leader in 1984 and later, in 1986, took up a 2 year position at Oxford University (UK) as a visiting scientist investigating maximum entropy applications to NMR signal processing (Newman 1988). Roger returned to work as a Research Scientist from 1987 at the DSIR (which became Industrial Research Limited in 1992) until 2004 when he accepted a position at Scion as a Principal Scientist in the area of bio-based materials (Newman et al. 2007). After a brief foray in 1974 into lanthanide induced proton chemical shift modelling (Newman and Neal 1974), Roger’s focus was directed toward the use of NMR to problems in natural materials and environmental science. Roger applied NMR to soil, coal and mineral research, utilising multinuclear and NMR relaxation experiments (Newman and Tate 1980; Newman and Davenport 1987; Parker et al. 1995). In 1979 Roger published the first paper in what was to become his primary area of expertise, NMR, to study the chemistry of plant biology and structure. Roger’s initial focus was on structural determination S. J. Hill (&) Biopolymers and Chemicals, 49 Sala Street, Private Bag 3020, Rotorua 3010, Bay of Plenty, New Zealand e-mail: stefan.hill@scionresearch.com

Safranine is an azo dye commonly used for plant microscopy, especially as a stain for lignified tissues such as xylem. Safranine fluorescently labels the wood cell wall, producing green/yellow fluorescence in the secondary cell wall and red/orange fluorescence in the middle lamella (ML) region. We examined the fluorescence behavior of safranine under blue light excitation using a variety of wood- and fiber-based samples of known composition to interpret the observed color differentiation of different cell wall types. We also examined the basis for the differences in fluorescence emission using spectral confocal microscopy to examine lignin-rich and cellulose-rich cell walls including reaction wood and decayed wood compared to normal wood. Our results indicate that lignin-rich cell walls, such as the ML of tracheids, the secondary wall of compression wood tracheids, and wood decayed by brown rot, tend to fluoresce red or orange, while cellulose-rich cell walls such as resin canals, wood decayed by white rot, cotton fibers and the G-layer of tension wood fibers, tend to fluoresce green/yellow. This variation in fluorescence emission seems to be due to factors including an emission shift toward red wavelengths combined with dye quenching at shorter wavelengths in regions with high lignin content. Safranine fluorescence provides a useful way to differentiate lignin-rich and cellulose-rich cell walls without counterstaining as required for bright field microscopy.

Lignocellulosic fibres harvested from different plant types exhibit variations in mechanical properties that are associated with their chemical composition and physical features. This diversity indicates that plant fibres could be selected based on their physio-chemical properties for tailored applications such as enhanced vibration damping. In this study, bast, leaf, and mesocarp fibre bundles were investigated to understand correlations between their physiochemical characteristics and their mechanical properties with a particular focus on their vibrational damping ability. Due to the interrelations between the investigated variables such as cellulose content and microfibril angle, a multivariate analysis (principal component analysis) was applied to elucidate trends. The stiffness and strength of the fibre bundles were found to be positively correlated to high cellulose content and low microfibril angle while high toughness was correlated with fibre bundles of high lignin content and high microfibril angle. Conversely, the damping coefficient was found to be positively correlated to fibres containing high level of hemicelluloses, such as those extracted from leafy plants.

Pretreating lignocellulosic biomass with certain ionic liquids results in structural and chemical changes that make the biomass more digestible by enzymes. In this study, pine wood was pretreated with 1-ethyl-3-methylimidazolium chloride/acetate ([C2 mim]Cl and [C2 mim][OAc]) at different temperatures to investigate the relative importance of substrate features, such as accessible surface area, cellulose crystallinity, and lignin content, on enzymatic digestibility. The ionic liquid pretreatments resulted in glucan conversions ranging from 23% to 84% on saccharification of the substrates, with [C2 mim][OAc] being more effective than [C2 mim]Cl. The pretreatments resulted in no delignification of the wood, some loss of cellulose crystallinity under certain conditions, and varying levels of increased surface area. Enzymatic digestibility closely correlated with accessible surface area and porosity measurements obtained using Simons' staining and thermoporosimetry techniques. Increased accessible surface area was identified as the principal structural feature responsible for the improved enzymatic digestibility.

CP MAS 13C NMR spectra of hardened resins have shown that urethane bridges derived from the reaction of the isocyanate group with the hydroxymethyl group of urea do form even at fast curing times comparable to what was used in the wood panels industry, in lower proportions than what was shown earlier. Polyureas and biurets obtained from the reaction of isocyanate with water are the predominant crosslinking reactions of pMDI alone and in UF/pMDI resin systems under fast curing conditions. Residual, unreacted isocyanate groups in the hardened network are consistently observed. Their proportion markedly decreases when the original proportion of urea–formaldehyde (UF) resin is high and that of pMDI is low. Under these fast curing conditions, the UF resin appears to self-condense through an unusually high proportion of methylene ether links rather than methylene bridges alone. A marked proportion of residual, unreacted hydroxymethyl groups is also noticeable, initially, in the UF self-condensation network. Direct NMR tests on thin hardboard bonded under fast pressing conditions with different proportions of UF/pMDI confirmed that crosslinking due to polyureas and biurets formation are predominant in the crosslinking of pMDI when alone and in UF/pMDI resin systems. They confirmed that residual, unreacted isocyanate groups are present in the finished panel. Their proportion is higher when the proportion of pMDI in the system is high. The presence or absence of urethanes could not be confirmed directly on the panels as the relevant peaks are masked by the wood carbohydrates signals of wood cellulose and hemicelluloses. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1624–1632, 2006

Extraction and recovery of radiata pine bark tannin for use in adhesives should endeavour to be optimal to ensure process viability. A NMR method has been developed to directly gauge the extent of tannin extraction from bark by analyzing processed residues. 13C Solid-state NMR spectra were obtained for a series of bark and residue samples. The respective peak areas and heights of extractable polyphenolic tannins were compared with residual lignocellulosic materials. From the ratio of NMR peak intensities, diminishing polyphenolic content was apparent with increasing degree of extraction. The percentage polyphenolic tannins removed by extraction could be estimated by a simple equation comparing integrated areas of a sample with those of pure bark. A comparison of percentage extraction values determined gravimetrically with NMR peak ratios gave a good relationship from which the extractables removed from a bark residue could be estimated, potentially providing a measurement of extraction efficiency...

Adsorption of 10–100 ppb lead and thallium by borosilicate glass and polypropylene surfaces was studied. No thallium was adsorbed by either substrate at pH 7.0. About 50–60% of the lead was adsorbed by borosilicate glass at pH 5.5 and pH 7.0, with statistically indistinguishable conditional equilibrium constants (KD∗ values) of 1.47±0.40 mL cm‐2 and 1.80±0.11 mL cm‐2, respectively. Polypropylene adsorbed significantly more lead than borosilicate glass at pH 7.0 (80.9%, KD∗ =5.33±0.45 mL cm‐2), and substantially less at pH 5.5 (16.7%, KD∗ = 0.27±0.03 mL cm‐2), indicating a fundamental change in the nature of the polypropylene surface. All adsorption data fitted Freundlich plots. Preliminary experiments indicate that at pH 5.5, a fraction of the lead sequestered by the borosilicate glass may be bound irreversibly by migrating into the glass matrix. The results suggest that tectosilicates and silicate glasses may represent important adsorbents of some heavy metals in soils, despite showing very low ...

Drying and rewetting of Pinus radiata sapwood latewood was studied by synchrotron wide angle X-ray scattering in transmission mode. Scattering from cellulose was interpreted in terms of chains distributed on a monoclinic lattice. Drying wood material to below the fibre saturation point resulted in decreased spacing between adjacent cellulose polymers within the hydrogen-bonded sheets of chains, and also decreased the monoclinic angle. The changes were partly reversed when the dried wood was rewet, but accumulated through multiple cycles of oven-drying and rewetting. No changes were observed in the fibre repeat distance, thus the distortion of the crystal lattice was not attributed to mechanical stresses associated with drying. Instead, the changes were attributed to formation of intrachain hydrogen bonds at dehydrated crystallite surfaces, causing conformational changes within the cellulose chains and increasing the density of packing. The results help account for the hysteresis observed in moisture desorption-adsorption isotherms during wood material drying and rehydration.

Two degradation products were obtained from the incubation of the widely used 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS, radical cations with the polyphenols, (+)-catechin, (-)-epicatechin, and phloroglucinol in acetate buffer (pH 5). The products were purified by reversed-phase chromatography and characterized by UV-visible detection, mass spectrometry, and (1)H NMR spectroscopy. The data allowed us to identify the degradation products as 3-ethyl-6-sulfonate benzothiazolinone imine and the corresponding sulfoxide, 3-ethyl-6-sulfonate benzothiazolone. Elemental composition strongly supported the proposed structures. Our results unequivocally demonstrated that ABTS radicals are not as stable as usually claimed because they could be degraded upon interaction with polyphenols, in addition to being reduced by these antioxidants back to the parent compound. Therefore, it is concluded that caution must be exercised in using ABTS radicals as a basis for the evaluation of antioxidant capacities of pure compounds and/or complex mixtures.

The determination of organic phosphorus (P) compounds in lake sediments can provide information on the potential for internal P loading. Settling seston and vertical sediment core samples from highly eutrophic Lake Okaro, New Zealand, were collected during a mixed winter and stratified summer period, representing, respectively, when the water column was well oxygenated and when the bottom waters were anoxic. Samples were analysed with 31P nuclear magnetic resonance (31P NMR) spectroscopy, which showed that both bottom sediments and settling seston contained orthophosphate, orthophosphate monoesters and diesters, pyrophosphates, polyphosphates and phosphonates. Phosphorus concentration in settling seston increased ~2.5-fold in winter as a result of seasonally induced changes in phytoplankton biomass, with a marked increase in the concentration of orthophosphate. Several potentially bioavailable P compounds in the bottom sediments were identified that were likely to contribute to recycling of P from the sediment to the water column. An ‘apparent half-life’ was used to quantify the time scales on which these compounds were recycled to the overlying water column. Orthophosphate monoesters that include inositol phosphates were the most persistent P compound. On the basis of half-lives, high internal P loadings may persist for more than 20 years, potentially hindering restoration efforts in Lake Okaro.

The industrial production of palm oil concurrently generates a substantial amount of empty fruit bunch (EFB) fibers that could be used as a feedstock in a lignocellulose-based biorefinery. Lignin byproducts generated by this process may offer opportunities for the isolation of value-added products, such as p-hydroxybenzoate (pBz), to help offset operating costs. Analysis of the EFB lignin by nuclear magnetic resonance (NMR) spectroscopy clearly revealed the presence of bound acetate and pBz, with saponification revealing that 1.1 wt% of the EFB was pBz; with a lignin content of 22.7 %, 4.8 % of the lignin is pBz that can be obtained as a pure component for use as a chemical feedstock. Analysis of EFB lignin by NMR and derivatization followed by reductive cleavage (DFRC) showed that pBz selectively acylates the γ-hydroxyl group of S units. This selectivity suggests that pBz, analogously with acetate in kenaf, p-coumarate in grasses, and ferulate in a transgenic poplar augmented with a feruloyl-CoA monolignol transferase (FMT), is incorporated into the growing lignin chain via its γ-p-hydroxybenzoylated monolignol conjugate. Involvement of such conjugates in palm lignification is proven by the observation of novel p-hydroxybenzoylated non-resinol β–β-coupled units in the lignins. Together, the data implicate the existence of p-hydroxybenzoyl-CoA:monolignol transferases that are involved in lignification in the various willows (Salix spp.), poplars and aspen (Populus spp., family Salicaceae), and palms (family Arecaceae) that have p-hydroxybenzoylated lignins. Even without enhancing the levels by breeding or genetic engineering, current palm oil EFB ‘wastes’ should be able to generate a sizeable stream of p-hydroxybenzoic acid that offers opportunities for the development of value-added products derived from the oil palm industry.