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Abstract Lignocellulose biomass has a tremendous potential as renewable biomaterials for fostering the “bio-based society” and circular bioeconomy paradigm. It requires efficient use and breakdown of fiber cell walls containing mainly cellulose, hemicellulose and lignin biopolymers. Despite their great importance, there is an extensive debate on the true structure of fiber walls and knowledge on the macromolecular nano-organization is limited and remains elusive in 3D. We employed dual-axis electron tomography that allows visualization of previously unseen 3D macromolecular organization/biopolymeric nano-architecture of the secondary S2 layer of Norway spruce fiber wall. Unprecedented 3D nano-structural details with novel insights into cellulose microfibrils (~ 2 nm diameter), macrofibrils, nano-pore network and cell wall chemistry (volume %) across the S2 were explored and quantified including simulation of structure related permeability. Matrix polymer association with cellulose varied between microfibrils and macrofibrils with lignin directly associated with MFs. Simulated bio-nano-mechanical properties revealed stress distribution within the S2 and showed similar properties between the idealized 3D model and the native S2 (actual tomogram). Present work has great potential for significant advancements in lignocellulose research on nano-scale understanding of cell wall assembly/disassembly processes leading to more efficient industrial processes of functionalization, valorization and target modification technologies.

Abstract Bioenergy will be one of the most important renewable energy sources in the conversion from fossil fuels to bio‐based products. Short rotation coppice Salix could be a key player in this conversion since Salix has rapid growth, positive energy balance, easy to manage cultivation system with vegetative propagation of plant material and multiple harvests from the same plantation. The aim of the present paper is to provide an overview of the main challenges and key issues in willow genetic improvement toward sustainable biofuel value chains. Primarily based on results from the research project “Optimized Utilization of Salix” (OPTUS), the influence of Salix wood quality on the potential for biofuel use is discussed, followed by issues related to the conversion of Salix biomass into liquid and gaseous transportation fuels. Thereafter, the studies address genotypic influence on soil carbon sequestration in Salix plantations, as well as on soil carbon dynamics and climate change impacts. Finally, the opportunities for plant breeding are discussed using willow as a resource for sustainable biofuel production. Substantial phenotypic and genotypic variation was reported for different wood quality traits important in biological (i.e., enzymatic and anaerobic) and thermochemical conversion processes, which is a prerequisite for plant breeding. Furthermore, different Salix genotypes can affect soil carbon sequestration variably, and life cycle assessment illustrates that these differences can result in different climate mitigation potential depending on genotype. Thus, the potential of Salix plantations for sustainable biomass production and its conversion into biofuels is shown. Large genetic variation in various wood and biomass traits, important for different conversion processes and carbon sequestration, provides opportunities to enhance the sustainability of the production system via plant breeding. This includes new breeding targets in addition to traditional targets for high yield to improve biomass quality and carbon sequestration potential.

Abstract Background Salix (willow) species represent an important source of bioenergy and offer great potential for producing biofuels. Salix spp. like many hardwoods, produce tension wood (TW) characterized by special fibres (G-fibres) that produce a cellulose-rich lignin-free gelatinous (G) layer on the inner fibre cell wall. Presence of increased amounts of TW and G-fibres represents an increased source of cellulose. In the present study, the presence of TW in whole stems of different Salix varieties was characterized (i.e., physical measurements, histochemistry, image analysis, and microscopy) as a possible marker for the availability of freely available cellulose and potential for releasing d-glucose. Stem cross sections from different Salix varieties (Tora, Björn) were characterized for TW, and subjected to cellulase hydrolysis with the free d-glucose produced determined using a glucose oxidase/peroxidase (GOPOD) assay. Effect of cellulase on the cross sections and progressive hydrolysis of the G-layer was followed using light microscopy after staining and scanning electron microscopy (SEM). Results Tension wood fibres with G-layers were developed multilaterally in all stems studied. Salix TW from varieties Tora and Björn showed fibre G-layers were non-lignified with variable thickness. Results showed: (i) Differences in total % TW at different stem heights; (ii) that using a 3-day incubation period at 50 °C, the G-layers could be hydrolyzed with no apparent ultrastructural effects on lignified secondary cell wall layers and middle lamellae of other cell elements; and (iii) that by correlating the amount of d-glucose produced from cross sections at different stem heights together with total % TW and density, an estimate of the total free d-glucose in stems can be derived and compared between varieties. These values were used together with a literature value (45%) for estimating the contribution played by G-layer cellulose to the total cellulose content. Conclusions The stem section-enzyme method developed provides a viable approach to compare different Salix varieties ability to produce TW and thus freely available d-glucose for fermentation and biofuel production. The use of Salix stem cross sections rather than comminuted biomass allows direct correlation between tissue- and cell types with d-glucose release. Results allowed correlation between % TW in cross sections and entire Salix stems with d-glucose production from digested G-layers. Results further emphasize the importance of TW and G-fibre cellulose as an important marker for enhanced d-glucose release in Salix varieties.

Abstract The incorporation of recycled papers, paperboards and Tetra Pak as filling materials in brittle matrices presents an interesting approach in the utilization of waste materials for building construction. This paper examines the compressive strength and microstructure of gypsum-bonded wastepaper-based composites. Recycled wastepaper of various types (office paper, magazine paper and newspaper), cardboards, paper boxes and Tetra Pak were shredded to short length strips of about 4 × 18 mm. The shredded materials were used as filling materials in natural gypsum in a ratio of 1:3 (v/v), and water was added to the mix. The paste was formed in cylindrical samples measuring 10 cm in length and 5 cm in diameter. Seven different types of composites were produced depending on the material used. The composite products with newspaper and magazine paper had significantly lower density and compressive strength (p

This study evaluated the potential of biochar impregnated with Fe3+ or Ca2+, or mixed with Polonite®, as a filter material for removal of phosphate (PO4-P) from wastewater in onsite wastewater treatment systems (OWTS). Four treatments with biochar were investigated: unimpregnated biochar (UBC), biochar impregnated with iron Fe3+ (FBC), biochar impregnated with calcium oxide (CBC), and biochar mixed with Polonite® (PBC). In a batch experiment using phosphate solution at concentrations 0.5, 3.3, 6.5, 13, and 26 mg PO4-P L–1, adsorption of PO4-P in the different treatments was modeled using Langmuir and Freundlich isotherms. Column filters (5 diameter × 55 cm height) packed with UBC, FBC, CBC, and PBC were then furnished with raw wastewater over 148 weeks. During this experiment, adsorption of PO4-P was investigated in response to increasing hydraulic loading rate (HLR; 56, 74, and 112 L m–2 day–1) and increasing phosphate loading rate (PLR; 195, 324, 653, and 1715 mg PO4-P m–2 day–1). Among the materials, FBC had the highest maximum adsorption capacity (Qm) based on Langmuir isotherms (3.21 ± 0.01 mg g–1). FBC and CBC showed robust performance with increasing HLR, while increasing PLR increased the amount of PO4-P retained in all filters. After 148 weeks of operation, removal of PO4-P (averaged over the last 18 weeks of operation) was 13 ± 16% for UBC, 40 ± 20% for CBC, 88 ± 12% for FBC, and 30 ± 18% for PBC. The PO4-P amount retained in filters over the 148 weeks was 84.75, 221.75, 358.38, and 152.36 g m–2 in UBC, CBC, FBC, and PBC, respectively. The adsorption capacity of the filters after 148 weeks was 1.50, 4.02, 6.41, and 2.75 mg g–1 for UBC, CBC, FBC, and PBC, respectively. The adsorption capacity values and breakthrough curves showed that low concentrations (i.e.,

Salix (willow) is a well-known coppice plant that has been used as a source for bioenergy for decades. With recent developments in changing from a fossil-based to a circular bioeconomy, greater interest has been orientated towards willow as a potential source of biomass for transport biofuels. This has created increasing interest for breeding strategies to produce interesting genotypic and phenotypic traits in different willow varieties. In the present study, 326 genetically distinct clones and several commercial varieties of S. viminalis were analyzed using complementary approaches including density, chemical, image, histochemical, and morphometric analyses. A systematic approach was adopted whereby the basal regions of harvested stems were separated and used in all studies to aid comparisons. Density analyses were performed on all clone individuals, and from the results, 20 individual plants representing 19 clones were selected for the more in-depth analyses (chemical, image analysis, histochemical, and morphometric). The absolute dry density of the clones selected varied between ca. 300 and 660 kg/m3 with less variation seen in the commercial S. viminalis varieties (ca. 450–520 kg/m3). Selected clones for chemical analysis showed the largest variation in glucose (47.3%–60.1%; i.e., cellulose) and total sugar content, which ranged between ca. 61 and 77% and only ca. 16 and 22% for lignin. Image analyses of entire basal stem sections showed presence of tension wood in variable amounts (ca. 7%–39%) with characteristic G-fibers containing cellulose-rich and non-lignified gelatinous layers. Several of the clones showing prominent tension wood also showed high glucose and total sugar content as well as low lignin levels. A morphometric approach using an optical fiber analyzer (OFA) for analyzing 1000 s (minimum 100,000 particles) of macerated fibers was evaluated as a convenient tool for determining the presence of tension wood in stem samples. Statistical analyses showed that for S. viminalis stems of the same density and thickness, the OFA approach could separate tension wood fibers from normal wood fibers by length but not fiber width. Results emphasized considerable variability between the clones in the physical and chemical approaches adopted, but that a common aspect for all clones was the occurrence of tension wood. Since tension wood with G-fibers and cellulose-rich G-layers represents an increased source of readily available non-recalcitrant cellulose for biofuels, S. viminalis breeding programs should be orientated towards determining factors for its enhancement.

Abstract Wood decayed by brown rot fungi and wood treated with the chelator-mediated Fenton (CMF) reaction, either alone or together with a cellulose enzyme cocktail, was analyzed by small angle neutron scattering (SANS), sum frequency generation (SFG) spectroscopy, Fourier transform infrared (FTIR) analysis, X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Results showed that the CMF mechanism mimicked brown rot fungal attack for both holocellulose and lignin components of the wood. Crystalline cellulose and lignin were both depolymerized by the CMF reaction. Porosity of the softwood cell wall did not increase during CMF treatment, enzymes secreted by the fungi did not penetrate the decayed wood. The enzymes in the cellulose cocktail also did not appear to alter the effects of the CMF-treated wood relative to enhancing cell wall deconstruction. This suggests a rethinking of current brown rot decay models and supports a model where monomeric sugars and oligosaccharides diffuse from the softwood cell walls during non-enzymatic action. In this regard, the CMF mechanism should not be thought of as a “pretreatment” used to permit enzymatic penetration into softwood cell walls, but instead it enhances polysaccharide components diffusing to fungal enzymes located in wood cell lumen environments during decay. SANS and other data are consistent with a model for repolymerization and aggregation of at least some portion of the lignin within the cell wall, and this is supported by AFM and TEM data. The data suggest that new approaches for conversion of wood substrates to platform chemicals in biorefineries could be achieved using the CMF mechanism with >75% solubilization of lignocellulose, but that a more selective suite of enzymes and other downstream treatments may be required to work when using CMF deconstruction technology. Strategies to enhance polysaccharide release from lignocellulose substrates for enhanced enzymatic action and fermentation of the released fraction would also aid in the efficient recovery of the more uniform modified lignin fraction that the CMF reaction generates to enhance biorefinery profitability.

Higher plants represent a large group of eukaryotes where centrosomes are absent. The functions of γ-tubulin small complexes (γ-TuSCs) and γ-tubulin ring complexes (γ-TuRCs) in metazoans and fungi in microtubule nucleation are well established and the majority of components found in the complexes are present in plants. However, plant microtubules are also nucleated in a γ-tubulin-dependent but γ-TuRC-independent manner. There is growing evidence that γ-tubulin is a microtubule nucleator without being complexed in γ-TuRC. Fibrillar arrays of γ-tubulin were demonstrated in plant and animal cells and the ability of γ-tubulin to assemble into linear oligomers/polymers was confirmed in vitro for both native and recombinant γ-tubulin. The functions of γ-tubulin as a template for microtubule nucleation or in promoting spontaneous nucleation is outlined. Higher plants represent an excellent model for studies on the role of γ-tubulin in nucleation due to their acentrosomal nature and high abundancy and conservation of γ-tubulin including its intrinsic ability to assemble filaments. The defining scaffolding or sequestration functions of plant γ-tubulin in microtubule organization or in nuclear processes will help our understanding of its cellular roles in eukaryotes.

Fungal wood decay strategies are influenced by several factors, such as wood species, moisture content, and temperature. This study aims to evaluate wood degradation characteristics of spruce, beech, and oak after exposure to the white-rot fungi Pleurotusostreatus and Trametesversicolor. Both fungi caused high mass losses in beech wood, while spruce and oak wood were more resistant to decay. The moisture content values of the decayed wood correlated with the mass losses for all three wood species and incubation periods. Combined microscopic and chemical studies indicated that the two fungi differed in their decay behavior. While T. versicolor produced a decay pattern (cell wall erosion) typical of white-rot fungi in all wood species, P. ostreatus caused cell wall erosion in spruce and beech and soft-rot type I (cavity formation) decay in oak wood. These observations suggest that P. ostreatus may have the capacity to produce a wider range of enzymes/radicals triggered by the chemical composition of wood cell walls and/or local compositional variability within the cell wall.

Sustainable and green synthesis of nanocomposites for degradation of pharmaceuticals was developed via immobilization and stabilization of the biological strong oxidizing agents, peroxidase enzymes, on a solid support. Sol−gel encapsulated enzyme composites were characterized using electron microscopy (TEM, SEM), atomic force microscopy, FTIR spectroscopy, and thermogravimetric analysis. Horseradish peroxidase (HRP) and lignin peroxidase (LiP) were adsorbed onto magnetite nanoparticles and sol−gel encapsulated in a surface silica layer. Encapsulation enhanced the stability of the biocatalysts over time and thermal stability. The biocatalysts showed appreciable selectivity in oxidation of the organic drinking water pollutants diclofenac, carbamazepine, and paracetamol with improved activity being pharmaceutical specific for each enzyme. In particular, sol−gel encapsulated LiP- and HRP-based nanocomposites were active over 20 consecutive cycles for 20 days at 55 °C (24 h/cycle). The stability of the sol−gel encapsulated catalysts in acidic medium was also improved compared to native enzymes. Carbamazepine and diclofenac were degraded to 68% and 64% by sol−gel LiP composites respectively at pH 5 under elevated temperature. Total destruction of carbamazepine and diclofenac was achieved at pH 3 (55 °C) within 3 days, in the case of both immobilized HRP and LiP. Using NMR spectroscopy, characterization of the drug decomposition products, and decomposition pathways by the peroxidase enzymes suggested.

This study aims to complement previous studies on down-regulation of sucrose synthase and cinnamate 4-hydroxylase in hybrid aspen (Bjurhager et al. 2010; Gerber et al. 2014) with a quantitative anatomical comparison (Sandquist et al. 2015). The main focus was placed on evaluating quantitative modifications to fiber morphology and lignin composition. This was achieved by combining results from light-, electron-, and UV-microscopy together with histochemical staining. Overall there was good agreement between the morphological results in this study compared to the previously published chemical and physical reports, particularly on cinnamate 4-hydroxylase down-regulated aspen. The previously reported statistical correlations between fiber lumen area and plant diameter, and fiber length and tree height (Sandquist et al. 2015) have been further refined. Knock-down of genes coding for biologically important proteins such as sucrose synthase and cinnamate 4-hydroxylase had broad spanning morphological impacts. Down-regulated sucrose synthase genotype showed significantly reduced fiber development, possibly with altered S/G ratio. Down-regulated cinnamate 4-hydroxylase genotype showed an overall reduction of lignin in fibers as indicated from both chemical staining and UV-microscopy measurements. Down-regulated pectate lyase genotype showed no overall significant effects on fiber morphology, ultrastructural, nor lignin staining.

Bamboo culms of Bambusa vulgaris Schrad. were collected from two locations in moist forests and two sites in derived Savanna zones in South West Nigeria. The study involved chemical analyses, density variability, bonding tests, gluability tests, and measurements of bending strength of the bamboo in addition to durability testing with decay fungi and treatability of glued boards with a copper-based wood preservative. Chemical analyses showed a uniform composition of the bamboo with a cellulose content of 45 to 47.5% and a lignin content of 23 to 25.6% as the predominant chemical constituents. An average wood density of 700 kg/m3 was a prerequisite for high mechanical strength. The moduli of elasticity were high and exceeded 14 kN/mm2 for bamboo boards and 13 kN/mm2 for finger joints. Bamboo boards from all growth sites showed high moduli of rupture in the range of 150 to 166 N/mm2 and 72.9 to 94.7 N/mm2 for boards and finger joints, respectively. Bamboo from the four sites showed variable mass loss with the EN-113 (1996) test method, which classifies this biomass as a moderately to non-durable plant material. White rot fungus (Trametes versicolor) caused the highest mass losses (11.2 to 16.8%). The bamboo showed good treatability using a 500-kg/m3 solution of a copper-based preservative.

The durability of thermally modified (TM) and untreated (UT) mini-stakes exposed to in-ground contact was compared by modulus of elasticity (MOE) and mass loss with decay type using microscopy. Results showed a strong correlation between MOE and soft rot decay for UT stakes over a 30 month exposure period. For TM stakes, the correlation between MOE and decay rate (soft rot/bacteria) was not as strong. Loss of MOE of the TM stakes is suggested to be accentuated by the extensive micro-checking produced in the TM wood tracheids during the original heat treatment. The micro-checks are thought to expand during the winter season due to water expansion during freezing, thereby leading to weakening of the wood in addition to the decay caused by soft rot and bacteria. Using molecular methods, Phialophora hoffmannii was identified as the main fungus causing soft rot decay.

This study outlines research concerning wheat straw fines, including their impact on pulp bleachability, their modification by chemical means, and their use as a dry strength enhancer in a paper application. Results show that primary fines constituting about 23% of the whole wheat straw pulp had a large negative impact on pulp bleachability. The differences in response to bleaching were due to the different properties of the fines, i.e. higher kappa number, higher metal ion content, lower brightness, and lower viscosity compared to that of fibers. It was also shown that the fines fraction is more difficult to oxidize and does not reach as high fiber charge levels as that of the other fractions. However, at a dosage of ≥ 3 mmol hypochlorite/g it was possible to prepare nanofibers from wheat straw fines that showed a good strength-enhancing effect in a paper product. The fact that removal of fines from wheat straw pulps by fractionation improves bleachability and also drainage properties at the same time, while simultaneously the fines can be modified and used as a strength enhancer, is very interesting when evaluating the potential of this type of annual plant as a source for production of different paper products.

Nano α-MnO2 is usually synthesized under hydrothermal conditions in acidic medium, which results in materials easily undergoing thermal reduction and offers single crystals often over 100 nm in size. In this study, α-MnO2 built up of inter-grown ultra-small nanoflakes with 10 nm thickness was produced in a rapid two-step procedure starting via partial reduction in solution in basic medium subsequently followed by co-proportionation in thermal treatment. This approach offers phase-pure α-MnO2 doped with potassium (cryptomelane type K0.25Mn8O16 structure) demonstrating considerable chemical and thermal stability. The reaction pathways leading to this new morphology and structure have been discussed. The MnO2 electrodes produced from obtained nanostructures were tested as electrodes of lithium ion batteries delivering initial discharge capacities of 968 mAh g−1 for anode (0 to 2.0 V) and 317 mAh g−1 for cathode (1.5 to 3.5 V) at 20 mA g−1 current density. At constant current of 100 mA g−1, stable cycling of anode achieving 660 mAh g−1 and 145 mAh g−1 for cathode after 200 cycles is recorded. Post diagnostic analysis of cycled electrodes confirmed the electrode materials stability and structural properties.

Recent studies on the ultrastructure and composition of the gelatinous layer (g-layer) in poplar have reported findings of xyloglucan. Using correlated fluorescence, scanning- and transmission electron micros-copy, we found evidence for xyloglucan present in and surrounding the g-layer, using the fucosylated xyloglucan specific CCRC-M1 antibody and the carbohydrate binding module FXG-14b. However, labeling of isolated gelatinous layer remained negative.

A new pulp fibre testing procedure called the HCl method was used to compare different spruce and pine fibres and mixtures of these fibres to calculate number of fibre cleavages in dislocations and other weak points. This method was compared with treatment of softwood kraft pulp fibres using different cellulase mixtures. The HCl method can distinguish between mill- and laboratory-made softwood kraft pulp fibres from the same wood batch. The sugar release is characterized by xylose and other hemicellulose sugars and little glucose. This is in contrast to cellulases, which despite strong fibre cleavage, did not distinguish between mill- and laboratory-made pulp fibres and released large amounts of glucose from the fibres. Hemicellulose degradation by HCl and deep penetration of the acid into the primary and secondary fibre cell walls at 80°C seems to be of major importance for the differentiation between mill and laboratory pulp fibres. Cellulases, in contrast, act mostly on the fibre surfaces, and deep penetration only takes place in amorphous regions of dislocations.

Electrode materials are critical for microbial fuel cells (MFC) since they influence the construction and operational costs. This study introduces a simple and efficient electrode material in the form of palm kernel shell activated carbon (AC) obtained in tropical regions. The novel introduction of this material is also targeted at introducing an inexpensive and durable electrode material, which can be produced in rural communities to improve the viability of MFCs. The maximum voltage and power density obtained (under 1000 Ω load) using an H-shaped MFC with AC as both anode and cathode electrode material was 0.66 V and 1.74 W/m3, respectively. The power generated by AC was as high as 86% of the value obtained with the extensively used carbon paper. Scanning electron microscopy and Denaturing Gradient Gel Electrophoresis (DGGE) analysis of AC anode biofilms confirmed that electrogenic bacteria were present on the electrode surface for substrate oxidation and the formation of nanowires.

233 Background: Cancer diagnosis and treatment brings about not only emotional upheavals but also logistical hurdles of navigating a fragmented healthcare system. Little is known about the frequency of healthcare contact for cancer patients and its implications. Healthcare contact days, defined as the number of days a patient spends in direct contact with healthcare professionals outside of home, measures the patient's interaction with the healthcare system. Methods: Using historical claims data (Part A institutional and Part B ambulatory claims) from the Enhancing Oncology Model (EOM) for 12 practices in The US Oncology Network covering the period between January 2019 to June 2022, we derived healthcare contact days per episode (6-month care periods initiating with the administration of chemotherapy), counting each unique date once. When patients encountered multiple care settings on a single date, the following hierarchy was used: inpatient (IP) > emergency room (ER) > skilled nursing facility (SNF)> hospice > ambulatory care. We further counted contact days for different services conducted during the ambulatory visits. Results: For the 75,246 episodes, an average of 31.9 days per episode (1 in every 6 days) were spent in healthcare contact. Cancer patients' healthcare contact was predominantly within ambulatory care, and visits with oncology providers exceeded that with all other specialties. ER and IP visits, generally a representation of acute care events, accounted for <10% of the contact days. Conclusions: During cancer treatment, patients spend approximately one-sixth of their time in healthcare contact. The optimal frequency of contact, pattern of primary care support, care of comorbidities, and the interrelationship between acute care and clinician visits are apt for further exploration. Healthcare contact days can reflect different care delivery approaches between providers and may be a metric to assess both healthcare efficiency and accessibility. Understanding caregiver burden and social disparities associated with high contact days offers an opportunity to improve care coordination and streamline healthcare encounters while balancing patients' care needs. CMMI Disclaimer: The statements contained in this document are solely those of the authors and do not necessarily reflect the views or policies of CMS. The authors assume responsibility for the accuracy and completeness of the information contained in this document. Healthcare contact days. Mean Percentiles 5th-95th Per Episode Healthcare Contact Days 31.9 10-65 Ambulatory Visits* 8-55 Chemotherapy 6.6 0-18 Imaging 2.7 0-7 Procedure 1.8 0-7 Radiation 2.4 0-23 Testing 11.8 3-25 Clinician Oncology 6 1-14 Other Specialties 3.4 0-10 Primary Care 2.8 0-8 Facility Visits ER 0.4 0-2 Hospice (Facility) 0.1 0-0 IP 2.7 0-16 SNF 0.8 0-0 *Ambulatory visits days are not mutually exclusive. [ABSTRACT FROM AUTHOR]

AbstractA study was carried out aiming at understanding the fundamental reasons for different fibre behaviour exhibited by Norway spruce and Scots pine causing large energy consumption differences during thermomechanical pulping (TMP). Ultrastructural characterization of TMP fibres and shives, which were sampled from the two wood species after primary refining, was performed using scanning electron microscopy, transmission electron microscopy (TEM) and TEM-immunogold labelling for their morphological and topochemical properties. As expected, pine wood chips needed higher electrical energy consumption to be refined to a given Canadian Standard Freeness and it produced inferior strength properties compared to spruce. Electron microscopy (EM) observations indicated that the mechanisms of fibre development during primary refining of pine and spruce were different. The two stages of pine fibre separation and development were not concurrent. Results indicated that pine fibre defibration/fracture occurred predominantly through the compound middle lamella/S1 interphase or through the S1 layer producing lesser amounts of shives during the primary refining stage than spruce. In contrast, spruce fibres defibrated mainly through the S2 layer. Detailed EM observations on shives and pulp fibres from TMP revealed the ultrastructural characteristics associated with pine fibre cell walls. Morphological and topochemical features of the S1 layer, S1/S2 interphase, such as lignin and galactoglucomannan distribution across cell walls were explored. The ultrastructural properties are discussed in relation to the TMP parameters (i.e., electrical energy consumption) and strength data. It is concluded that ultrastructural characteristics of Scots pine fibre cell walls govern the different fibre development mechanisms and explain the negative response of this wood during TMP processing. [ABSTRACT FROM AUTHOR]

Abstract  Due to the increasing demand for Norway spruce as prime raw material for high-yield pulping, recent interest has focused on Scots pine as an alternative. However, the intrinsic properties of Scots pine, particularly the high amounts of extractives and the fiber properties, have been considered a disadvantage for thermomechanical pulping. A study was therefore conducted on the variations in the spatial distribution and redistribution of lipophilic extractives in spruce and pine wood and thermomechanical pulp (TMP) using cytochemical staining methods and chemical analysis. Chemical analyses showed chips from pine thinnings and sawmill slabs to contain three to five and two to three times, respectively, more extractives than found in spruce; in particular, the amount of triglycerides differed significantly. Results from staining techniques on the abundance and distribution of extractives (i.e., fats) between pine and spruce correlated with amounts detected by Fourier transform infrared spectroscopy and gel permeation chromatography. Cytochemical observations revealed information pertaining to species-specific distribution and redistribution of extractives among TMP fines and fibers and indicated the presence of a molecular film of extractives. Results indicate that the high concentrations of extractives in pine ray parenchyma are released during TMP processing and are redistributed onto the surfaces of the pulps, negatively affecting energy usage during primary refining. [ABSTRACT FROM AUTHOR]

AbstractThe aim of the present study was to determine the effect of a variety of abnormal fibres on the mechanical properties of paper made from Norway spruce, Picea abies(L.) Karst. Fibres representing abnormality were obtained from trees treated by irrigation and fertilisation. Moreover, fibres from compression wood and its accompanying opposite wood were isolated. The effect of dislocations on paper quality was studied on four mixtures (20, 40, 60 and 80% fibres with induced dislocations) of untreated/compressed fibres. Two more groups consisting of control untreated samples and samples with 100%-induced dislocations were also included in the test. The mechanical properties of the paper were tested and the results were compared to those of control samples. Abnormal fibres reduced the desired mechanical properties of the final paper concerning tensile strength, modulus of elasticity and tear-tensile index. Irrespective of the type of treatment, all morphological changes introduced in fibre cell walls appear to directly affect changes in the mechanical properties of the paper. Control samples had a tear index of 25 compared to 10 mN m2g-1of samples containing 100% dislocations. It is obvious that 20% of dislocations, an amount that is expected to be induced in pulp under mechanical processing and transport, will contribute to a decrease in tear index with an average of 3 mN m2g-1, i.e., 10% of the total value. [ABSTRACT FROM AUTHOR]

AbstractAn amino-silicone (AS; amino-polydimethylsiloxane) micro-emulsion was tested for its suitability to preserve wood against basidiomycetes in a mini-block experiment and in a test according to the European standard (1996) EN 113. Decay resistance was assessed against the white rot fungi Trametes versicolor, Ceriporiopsis subvermispora, and Hypoxylon fragiforme, as well as the brown rot fungi Coniophora puteana, Antrodia vaillantii, Gloeophyllum trabeumand Serpula lacrymans. Pine sapwood and beech wood were treated with AS emulsions at solute concentration levels of 2%, 5% and 15%. The mini-blocks treated with 15% concentrations of AS resisted decay by T. versicolorand C. puteanaover a long time (12 weeks), while samples treated with low and moderate concentrations underwent considerable mass losses. Accordingly, microscopic studies revealed a high degree of colonisation by the white rot fungus and loss of cell wall integrity (brown rot) in samples treated with 2% AS. At high AS content (15%), no or only initial stages of decay could be observed. In the European standard (1996) test EN 113, the mass loss in all fungal cultures except for the white rot ascomycete H. fragiformewas below 5%, when the samples were treated with 15% AS. The effect of low and moderate AS concentration on the decay resistance was dependent on the fungal strain. The mode of action of AS treatment against basidiomycete decay is discussed. [ABSTRACT FROM AUTHOR]

AbstractAxial compressive stresses can cause distortion of the cellulose fibril alignment in the wood cell wall. These deformations are thought to occur in the living tree and/or to develop during wood processing and seem to adversely affect the mechanical properties of pulp and paper and other fibre-based products. To characterise the influence of dislocations on the mechanical properties of the unmodified cell wall, dislocations were artificially created by applying high compression loads to wood blocks parallel to the fibre axis. Mechanically isolated fibres containing different levels of dislocations were then subjected to tensile tests. Comparison between micromechanical properties of reference fibres and fibres that were artificially loaded in compression revealed the importance of dislocations for the mechanics of both earlywood and latewood. However, the tensile strength (decrease ∼19% for earlywood and ∼26% for latewood) was less affected than expected from structural observations of the pre-compressed zones. [ABSTRACT FROM AUTHOR]

AbstractThe distribution of lignin, carbohydrates, and metal ions on the surface of spruce and aspen wood tissue sections was investigated by time-of-flight secondary ion mass spectrometry (ToF-SIMS). The distribution patterns of metals and lignin in ray cells, vessels, and fibres were different, whereas carbohydrates were uniformly distributed across the sections of all morphological regions. In spruce sapwood, Ca, Mg, Na, K, Fe locations was more pronounced in the bordered pit tori and inner layer of ray parenchyma cells. Little lignin was detected in these regions. In spruce heartwood, the degree of lignification was low on the surfaces of bordered pit tori; however, Na and K were not detected here. In compression wood from spruce, the locations of p-hydroxyphenyl and guaiacyl units was different in cell wall layers. In aspen sapwood, the main locations of Ca, Mg, Na, K were in lumina of longitudinal parenchyma cells and in pits between vessels and ray cells. Low-intensity signals of the secondary ions assigned to lignin were found in the same morphological regions. [ABSTRACT FROM AUTHOR]

Abstract  The three-dimensional structure of a transverse sawn wood surface was investigated using several methods, to compare techniques, and to study the types of deformation in tracheids at the saw cut. A sample of spruce sapwood was cut with a fret saw across the grain. The transverse sawn surface was imaged by confocal microscopy, field emission scanning electron microscopy (FESEM), and by light microscopy combined with serial sectioning and three-dimensional (3D) reconstruction. Both confocal microscopy and FESEM were restricted to visualising the cut surface of the wood. However, serial sectioning was able to reveal the internal structure below the cut surface providing more information on the types of cell deformation present. The wood structure was deformed to depths of more than 600 μm below the surface with twisting, crushing and tearing deformations. Near the outer surface, gaps were formed between groups of tracheids where the cell walls had been torn away to form saw dust. The deformation tended to form groups of tracheids that were twisted relative to each other. Latewood was less distorted, forming a dense solid surface compared to the highly fibrous earlywood. [ABSTRACT FROM AUTHOR]

AbstractA study was performed on stone groundwood (SGW) pulps produced on a pilot scale. The behaviour of selected juvenile and mature Norway spruce wood samples was investigated. As revealed by standard tests, sheets formed from juvenile wood showed improved light scattering properties, improved tear and tensile strength, and higher sheet density compared to those formed from mature wood. Scanning electron microscopy indicated that the differences are likely related to the manner of fibre processing and development at the ultrastructural level. Mature wood fibres showed greater fibre end breakage, a smaller long-fibre fraction, enhanced S1 fibrillation and frequently open fibres. In contrast, juvenile fibres had a 14% higher long-fibre fraction and showed typical S2 fibrillation. Fibre development of juvenile wood showed fibrillation features similar to those previously reported for thermomechanical pulp fibres. In both cases, the structural hierarchy of the wood fibre cell wall and the microfibril angle of S2 and S1 layers govern cell-wall splitting and fibrillation progression. The superior quality of the fibre furnish prepared from juvenile fibres compared to mature fibres with SGW pulping may offer an alternative process for more effective utilisation of raw materials such as top logs rich in juvenile wood. [ABSTRACT FROM AUTHOR]

Wood “cell-wall deformation” is a comprehensive term describing any physical dislocation in the wall caused by mechanical forces. The development and effect of fibre dislocations on wood fibres, and their ultimate impact on the mechanical properties of paper remain rather obscure and controversial. Dislocations are difficult to quantify through a lack of defined measurable features, and research is aggravated by the inherent difficulties of applying statistical tools. A direct approach for studying the effect of dislocations on the mechanical properties of paper was used in this study. Dislocations in fibre cell walls were introduced by exposing whole wood fibres in mature and juvenile wood samples to compression stress. Sapwood samples of Norway spruce ( Picea abies Karst.) were loaded by compression to their ultimate strength using an Alwetron-50 universal testing machine. Failure of samples conditioned to a moisture content of 9–15% always occurred in an oblique (relative to the fibre axis) plane and all fibres in the plane were deformed. When samples were loaded in a wet condition (i.e., moisture content close to the fibre saturation point), failure occurred at one end of the samples, resulting in highly disorganised fibres. Pulp and paper from the compressed fibres were produced and the mechanical properties of the paper were tested. Results of the mechanical tests were compared statistically to results derived from paper made from matched non-compressed control samples. Morphological features of fibres and dislocations after compression failure were characterised using microscopy (scanning electron microscopy, polarised light) on the whole wood and macerated fibres before and after paper testing. The above experimental approach showed that paper made from control samples had significantly better mechanical properties than paper made from samples loaded by compression under dry or wet conditions. At a tensile index of 90 N m/g, the tear index was measured as 23.6 mN m 2 /g for controls, while the corresponding values for compressed wet wood samples was 12.6 and 16.3 mN m 2 /g for samples at 9–15% moisture content. Paper made from juvenile wood also showed lower mechanical properties compared to controls. The results prove the negative effect of dislocations on the mechanical properties of paper in the worst case scenario and are of practical importance. [ABSTRACT FROM AUTHOR]

AbstractBirch and pine wood specimens were colonized by individual isolates of 12 brown-rot, 26 white-rot, six soft-rot and four blue (sap)-stain fungi. Homogenized wood was subsequently extracted in 75% ethyl acetate and centrifuged. The filtered extracts were analyzed for their iron-reducing capabilities using a ferrozine-based assay. Agar fungal cultures were also examined directly using a spot test for iron reduction. Extracts from wood colonized by brown-rot fungi showed significantly greater iron-reducing capability than extracts from wood colonized by white-rot or non-decay fungi. Results of the spot test ratings were highly variable, but in general the greatest color responses were associated with the brown-rot cultures. The ability of brown-rot fungi to produce compounds and/or modify the wood components that reduce iron is of relevance to the “chelator-mediated Fenton mechanism” that has been advanced as a theory for the non-enzymatic degradation of wood by brown-rot fungi. [ABSTRACT FROM AUTHOR]

AbstractThe gelatinous layer (G-layer) formed on the lumen wall in early- and latewood fibres of poplar and birch tension wood was characterised using a novel molecular marker specific for crystalline cellulose in conjunction with fluorescence and FE-SEM microscopy. Crystalline cellulose was localised using a cloned Cel7A cellulose-binding module (CBM1HjCel7A) from the fungus Hypocrea jecorinaconjugated directly to FITC/TRITC or indirectly via a secondary antibody conjugated to FITC for fluorescence microscopy or to gold/silver for FE-SEM. With the CBM1HjCel7Aconjugate, the G-layer was clearly distinguished from other secondary cell-wall layers as a bright green layer visible in fibres of tension wood in fluorescence microscopy. FEM-SEM images revealed the supramolecular architecture of the G-layer of poplar wood, which consists of well-defined, often concentrically orientated, cellulose aggregates of the order of 30–40 nm. The cellulose aggregates typically have a microfibril angle of almost 0°. Studies on cellulose marked with CBM1HjCel7Afollowed by Au labelling and Ag enhancement complemented the fluorescence observations. The studies demonstrate the usefulness of this novel molecular marker for crystalline cellulose in situ, which was previously difficult to localise. Further proof of distinct cellulose aggregates was observed. [ABSTRACT FROM AUTHOR]