| 1. |
- Edvardsson, Johannes, et al.
(författare)
-
Old wood in a new light : an online dendrochronological database
- 2023
-
Ingår i: International Journal of Wood Culture. - : Brill Academic Publishers. - 2772-3194 .- 2772-3186. ; 3:1-3, s. 442-463
-
Tidskriftsartikel (refereegranskat)abstract
- The Old Wood in a New Light database project focuses on the digitization and accessibility of the results of dendrochronological samples analyzed and archived at four Swedish university-based tree-ring laboratories at Lund University, Stockholm University, University of Gothenburg, and the Swedish University of Agricultural Sciences. Collaboration with the Environmental Archaeology Laboratory and Humlab at Umeå University enables long-term open access to data, raw data, and metadata. In this project, we (1) systematically undertake large-scale entry and open access publication of results from wood samples scientifically analyzed and archived by Swedish laboratories and the associated metadata, into the Strategic Environmental Archaeology Database (SEAD; www.sead.se) research data infrastructure, and (2) actively promote the database as a resource for new and ongoing interdisciplinary research initiatives. Including dendrochronological data in SEAD infrastructure allows interdisciplinary studies that combine major scientific and societal questions. Building on a pilot study of construction timber from southern Sweden and adaptation of SEAD digitization workflows, more than 70 000 samples archived at the four dendrochronological laboratories are now being handled in the project. The broad coverage of research networks, stakeholder interaction, and strategic support from the cultural heritage community is guaranteed owing to the ongoing collaboration between laboratories and an established international and multidisciplinary reference group.
|
|
| 2. |
- Neyses, Benedikt, 1986-, et al.
(författare)
-
Continuous densification of solid wood – The belt press approach
- 2022
-
Ingår i: Proceedings of the 10th European Conference on Wood Modification. - Nancy : University of Lorraine, Faculty of Science and Technology, Laboratory of Study and Research on the Wood Material (LERMaB). ; , s. 76-79
-
Konferensbidrag (refereegranskat)abstract
- The densification, i.e., transverse compression of solid wood can lead to improvements in the mechanical properties, and this can expand the areas of application for low-density wood species. For the past one hundred years, many efforts have been made to mass-produce densified wood products, but despite being available on the market, they remain niche products with low annual production volumes. One of the main reasons for this is that all available densified wood products are produced in a batch-type process, which limits the achievable process speed and integration into the continuous wood processing chain. For this reason, we propose a continuous surface densification process using a bespoke belt press – similar in principle to those used to produce MDF panels. The belt-press is capable of densifying full-sized wood boards at processing speeds of up to 60 m min-1. The primary belt for densification can be heated to temperatures above 160°C, while a subsequent belt functions as a cooling stage. During the densification process, the belt press can log the pressing forces, moments, and temperature. Preliminary tests with Scots pine specimens of 120 mm in width and 38 mm in thickness resulted in a twofold increase in peak density, after a pressing time of two minutes at 120°C. The resulting density profiles were similar to those obtained in studies using a static hot press. As the belt press can be fed with a continuous stream of boards, it has a higher net throughput than a static hot press. Further studies continue with the aim to evaluate different aspects relevant to the large-scale industrial production of densified wood products.
|
|
| 3. |
- Ahmed, Sheikh Ali, Senior Lecturer, 1977-, et al.
(författare)
-
Anatomical, Physical, Chemical, and Biological Durability Properties of Two Rattan Species of Different Diameter Classes
- 2022
-
Ingår i: Forests. - Switzerland : MDPI. - 1999-4907. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Rattan cane is an important forest product with economic value. Its anatomical, physical, and biological properties vary with the cane height. This makes it difficult to select the appropriate cane diameter for harvesting. Understanding the material properties of rattan cane with different diameter sizes is important to enhance its utilization and performance for different end uses. Thus, the present study was performed on two rattan species, Calamus zollingeri and Calamus ornatus, at two different cane heights (bottom/mature and top/juvenile). Calamus zollingeri was studied at diameter classes of 20 mm and 30 mm, while Calamus ornatus was analyzed at a diameter class of 15 mm. The anatomical properties, basic density, volumetric swelling, dynamic moisture sorption, and biological durability of rattan samples were studied. The results showed that C. zollingeri with a 20 mm diameter exhibited the highest basic density, hydrophobicity, dimensional stability, and durability against mold and white-rot (Trametes versicolor) fungi. As confirmed by anatomical studies, this could be due to the higher vascular bundle frequency and longer thick-walled fibers that led to a denser structure than in the other categories. In addition, the lignin content might have a positive effect on the mass loss of different rattan canes caused by white-rot decay.
|
|
| 4. |
- Amiandamhen, Stephen, 1983-, et al.
(författare)
-
Bioenergy production and utilization in different sectors in Sweden: A state of the art review
- 2020
-
Ingår i: BioResources. - : University of North Carolina Press. - 1930-2126. ; 15:4, s. 9834-9857
-
Forskningsöversikt (refereegranskat)abstract
- In the continual desire to reduce the environmental footprints of human activities, research efforts to provide cleaner energy is increasingly becoming vital. The effect of climate change on present and future existence, sustainable processes, and utilizations of renewable resources have been active topics within international discourse. In order to reduce the greenhouse gases emissions from traditional materials and processes, there has been a shift to more environmental friendly alternatives. The conversion of biomass to bioenergy, including biofuels has been considered to contribute to the future of climate change mitigation, although there are concerns about carbon balance from forest utilization. Bioenergy accounts for more than one-third of all energy used in Sweden and biomass has provided about 60% of the fuel for district heating. Apart from heat and electricity supply, the transport sector, with about 30% of global energy use, has a significant role in a sustainable bioenergy system. This review presents the state of the art in the Swedish bioenergy sector based on literature and Swedish Energy Agency’s current statistics. The review also discusses the overall bioenergy production and utilization in different sectors in Sweden. The current potential, challenges, and environmental considerations of bioenergy production are also discussed.
|
|
| 5. |
- Andersson, Johanna, et al.
(författare)
-
Comparison of steaming and boiling of root vegetables for enhancing carbohydrate content and sensory profile
- 2022
-
Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 312
-
Tidskriftsartikel (refereegranskat)abstract
- Root vegetables have unique techno-functional and nutritional properties however, their use in processed foods is limited to a few species, partially due to a lack of knowledge related to the impact of thermal treatments on the sensory properties. This study investigated the effect of steaming and boiling on the microstructure, mechanical properties, and sensory profile of three model root vegetables with distinct carbohydrate composition: Jerusalem artichoke (Helianthus tuberosus L.), parsnip (Pastinaca sativa), and beetroot (Beta vulgaris). Thermally treated Jerusalem artichoke and parsnip showed higher content of cell wall polysaccharides, particularly β-glucans (e.g. cellulose) and pectic components, compared to raw. Steaming produced more cell shrinkage and loss of cell-cell adhesion than boiling, leading to softer vegetables. Processed beetroot showed loss of cell turgor and drastic softening but not clear changes in overall carbohydrate content. The scores for several flavour and in-mouth attributes were higher for steamed vegetables compared to boiled. Our results give insights on the processability of root vegetables towards products with enhanced sensory and nutritional properties.
|
|
| 6. |
- Daniel, Geoffrey
(författare)
-
Decay capacity and degradation patterns of Xylaria hypoxylon on different wood species
- 2022
-
Ingår i: Proceedings IRG Annual Meeting. - 2000-8953.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A host of physical and environmental factors may influence fungal decay including the wood substrate, temperature, moisture, oxygen, light, pH, and nitrogen. Understanding the effects of these factors on fungal decay is important for the effective utilization of wood decay fungi in biotechnological processes and for understanding the role of these organisms in global carbon cycling. The ascomycete Xylaria hypoxylon causes white rot of hardwoods, but remains relatively under-characterized. In this investigation, the decay capability of this fungus was studied using beech, hornbeam, oak and pine. Although Xylaria species are considered as causing white rot decay, Type II soft rot erosion was observed on hornbeam, Type I soft rot cavities were noted on beech, simultaneous rot was found on oak and selective rot on pine. Results indicated that both wood species and cell wall chemistry affected morphological decay patterns illustrating the relationships between fungal enzymatic capacity and wood cell wall structure/chemistry.
|
|
| 7. |
- Erlandsson, Martin, et al.
(författare)
-
Underlagsdata för hållbarhetsbedömning i BioMapp
- 2024
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport utgör en samlad dokumentation av underlags data, med avseende på de olika industriprocesser som ingår i visualiseringsverktyget BioMapp. De skogsindustriella processerna som beskrivs i rapportens bilagor baseras på en allmänt accepterad inventeringsmetodik för att beskriva skogsbaserade produkters miljöpåverkan och andra hållbarhetsindikatorer i ett livscykelperspektiv. Det systemanalytiska verktyg som används i projektet är livscykelanalys (LCA) på så sätt som det tillämpas i miljövarudeklarationer för produkter (EPD).De inventeringsdata som redovisas har en ambition att vara representativa för den typ av processer och miljöbelastning som är relevanta för svenska förhållande. Det har dock inte varit möjligt inom ramen för projektet att göra kompletta branschsammanställningar.
|
|
| 8. |
- Escamez, Sacha, 1987-, et al.
(författare)
-
Genetic markers and tree properties predicting wood biorefining potential in aspen (Populus tremula) bioenergy feedstock
- 2023
-
Ingår i: Biotechnology for Biofuels and Bioproducts. - : BioMed Central Ltd. - 2731-3654. ; 16:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Wood represents the majority of the biomass on land and constitutes a renewable source of biofuels and other bioproducts. However, wood is recalcitrant to bioconversion, raising a need for feedstock improvement in production of, for instance, biofuels. We investigated the properties of wood that affect bioconversion, as well as the underlying genetics, to help identify superior tree feedstocks for biorefining. Results: We recorded 65 wood-related and growth traits in a population of 113 natural aspen genotypes from Sweden (https://doi.org/10.5061/dryad.gtht76hrd). These traits included three growth and field performance traits, 20 traits for wood chemical composition, 17 traits for wood anatomy and structure, and 25 wood saccharification traits as indicators of bioconversion potential. Glucose release after saccharification with acidic pretreatment correlated positively with tree stem height and diameter and the carbohydrate content of the wood, and negatively with the content of lignin and the hemicellulose sugar units. Most of these traits displayed extensive natural variation within the aspen population and high broad-sense heritability, supporting their potential in genetic improvement of feedstocks towards improved bioconversion. Finally, a genome-wide association study (GWAS) revealed 13 genetic loci for saccharification yield (on a whole-tree-biomass basis), with six of them intersecting with associations for either height or stem diameter of the trees. Conclusions: The simple growth traits of stem height and diameter were identified as good predictors of wood saccharification yield in aspen trees. GWAS elucidated the underlying genetics, revealing putative genetic markers for bioconversion of bioenergy tree feedstocks. © 2023, The Author(s).
|
|
| 9. |
- Fundová, Irena
(författare)
-
Quantitative genetics of wood quality traits in Scots pine
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wood quality of commercial tree species is important for many wood processingindustries and thus should be considered for inclusion in forest tree improvementprograms. This thesis evaluated the suitability of various proxy methods for rapid andnon-destructive assessment of wood quality traits on standing trees of Scots pine and thepotential for genetic improvement of different wood quality traits through recurrentselective breeding.Penetrometer Pilodyn and micro-drill Resistograph were tested for non-destructiveassessment of wood density (DENPIL and DENRES, respectively), using SilviScan density(DENSILV) as a benchmark. A strong additive genetic correlation was observed betweenDENSILV and DENRES (rA = 0.96), whilst the correlation with DENPIL was substantiallylower (rA = 0.74). Furthermore, SilviScan stiffness (MOESILV) was used as a benchmarkfor evaluation of several approaches of calculating the dynamic modulus of elasticity(MOE) from standing-tree acoustic velocity (VELTREE). The combination of VELTREEand adjusted DENRES provided the most accurate estimate of MOETREE (rA = 0.91).Additionally, non-destructive acoustic sensing tools were tested at different stages ofwood processing (on standing trees, felled logs and sawn boards) using destructivelymeasured sawn-board stiffness (static modulus of elasticity, MOES) and strength(modulus of rupture, MOR) as benchmarks. They proved to be capable of accuratelypredicting MOES (rA ≈ 0.8) while VELTREE, adjusted DENRES and MOETREE wellreflected MOR (rA ≈ 0.9). Genetic variation of shape stability of sawn boards (bow, crookand twist) was also investigated. Under-bark grain angle (GRA) was found to be a goodpredictor of sawn-board twisting and crooking (rA = 0.84 and 0.62, respectively). Thechemical composition of juvenile wood (proportion of cellulose, hemicelluloses, ligninand extractives) was predicted from Fourier transform infrared (FTIR) spectra usingpartial least squares regression (PLSR) modeling. Individual-tree narrow-senseheritabilities (ℎi2) for all of the studied wood quality traits varied from low to moderate.Genetic improvement of sawn-board DEN, MOES and MOR as the target traits couldbe achieved through selective breeding for MOETREE, DENRES, stem straightness (STR)or GRA. Selection focusing on GRA would also result in lower bow, crook and twist.Despite the negative genetic correlations between growth and wood quality traits, apossibility of their simultaneous improvement was identified. An index combining stemdiameter (DBH) and MOETREE provided the best compromise.
|
|
| 10. |
|
|
| 11. |
- Jones, Grace
(författare)
-
Birch Stem and Wood Traits in Genetic and Silviculture Trials in Southern Sweden
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Swedish tree species of birch (silver: Betula pendula and downy: B. pubescens) are often neglected during forest management activities, resulting in low value logs. This thesis investigated birch stem characteristics and wood properties important for solid wood products, in genetics and management trials in southern Sweden. As well as visual stem size and form measurements, non-destructive testing and evaluation (NDT) tools were used to indirectly estimate wood density (hardness), wood stiffness, and grain angle.The results of this work suggest that for the 19-year-old silver birch and 15-year-old downy birch sites, important solid wood traits were under a reasonable degree of genetic control. It seems possible to breed birch to improve grain angle since heritability and genetic variation was high for this trait. Silver birch genotypes are expected to perform similarly across sites. At a site with both birch species, silver birch was larger with denser wood than downy birch. Few genetic correlations between measurements means selection for one trait will not inadvertently affect another trait. The radial density profiles showed density was continuing to increase. Acoustic velocity (AV) and fibre length were highly correlated, hardness and density were related, and ring width was related to ring density. In a 35-year-old planted Norway spruce stand, naturally regenerated birch AV was not different between treatments (20% or 50% of plot trees were birch by number). However, a correlation was observed between DBH and AV. This older site may reflect common Swedish conditions since planting birch is rare, and likely had more mature birch wood than the genetics trials. Although meeting an immediate need for studies of birch wood properties from managed stands, this work covered few sites. To meet this limitation the tools and techniques applied in this thesis could be used in further studies. The results of this thesis work will be of interest to forest managers who want to breed birch, or select birch stands, for solid wood products.
|
|
| 12. |
- Jones, Grace, et al.
(författare)
-
Genetic Parameters of Stem and Wood Traits in Full-Sib Silver Birch Families
- 2021
-
Ingår i: Forests. - : MDPI. - 1999-4907. ; 12:2, s. 1-17
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigated heritability of stem and wood traits to improve Swedish silver birch (Betula pendula Roth.) through breeding. Birch is 12% of Sweden’s forest area but mainly used for low value pulp or firewood. This paper applied non-destructive test (NDT) methods, and estimated traits’ heritability (h2), to help breed birch for high value solid wood products. Two trials of 22 families were assessed at age 19 for stem diameter (DBH), stem straightness, rough brown bark height (BH), grain angle (GA), Pilodyn penetration depth (Pilo) and acoustic velocity (AV). X-ray densitometry was performed on a subsample of radial cores taken at 1.3 m from the ground to get an average benchmark density. The h2 values were moderate for GA (0.20 and 0.21) and Pilo (0.53 and 0.48) at the two sites, but the h2 values for AV were low (0.05 and 0.30). There were moderate genotypic correlations between BH and DBH (0.51–0.54). There were low genotypic and phenotypic correlations between NDT measurements and other traits so including NDT in birch breeding efforts should not inadvertently reduce size, stem or wood quality. The high genetic correlations between sites suggest that GA, Pilo and AV values were determined more by genotype than by environment.
|
|
| 13. |
- Jones, Grace, et al.
(författare)
-
Non-Destructive Evaluation of Downy and Silver Birch Wood Quality and Stem Features from a Progeny Trial in Southern Sweden
- 2023
-
Ingår i: Forests. - : MDPI. - 1999-4907. ; 14:10
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigated whether improved downy birch could perform as well as improved silver birch, and whether there was sufficient genetic variation and control for non-destructive testing (NDT) values to include them as selection traits in breeding programs. NDT tools were applied to a 15-year-old downy birch family trial intermixed with improved silver birch. Average diameters, fissured bark height, and grain angle were higher for silver than downy birch. The genetic analysis for downy birch provided estimates of narrow-sense heritability (h2) for acoustic velocity and Pilodyn penetration depth that were above 0.3 but had low genetic variation. Grain angle had relatively high genetic variability (18%) and an h2 of 0.20. A subsample of 49 trees had 4 mm cores x-rayed for wood density estimates, and 34 stems had 12 mm cores macerated for cell measurements. t-tests revealed that average wood density and cell measurements were not significantly different between species. For silver and downy birch, fiber length and vessel length increased between inner and outer measurement positions, and fiber length was reasonably correlated with acoustic velocity. Silver birch tended to have denser and stiffer wood, while downy birch had less rough bark and straighter grain, and these results are in agreement with existing knowledge. The h2 values were similar to those observed in other birch species and indicate there is potential to breed for improved wood density and grain angle in downy birch.
|
|
| 14. |
- Jones, Grace, et al.
(författare)
-
Relating estimates of wood properties of birch to stem form, age and species
- 2024
-
Ingår i: Journal of Forestry Research. - : Springer. - 1007-662X .- 1993-0607. ; 35:1
-
Tidskriftsartikel (refereegranskat)abstract
- Birch has long suffered from a lack of active forest management, leading many researchers to use material without a detailed management history. Data collected from three birch (Betula pendula Roth, B. pubescens Ehrh.) sites in southern Sweden were analyzed using regression analysis to detect any trends or differences in wood properties that could be explained by stand history, tree age and stem form. All sites were genetics trials established in the same way. Estimates of acoustic velocity (AV) from non-destructive testing (NDT) and predicted AV had a higher correlation if data was pooled across sites and other stem form factors were considered. A subsample of stems had radial profiles of X-ray wood density and ring width by year created, and wood density was related to ring number from the pith and ring width. It seemed likely that wood density was negatively related to ring width for both birch species. Linear models had slight improvements if site and species were included, but only the youngest site with trees at age 15 had both birch species. This paper indicated that NDT values need to be considered separately, and any predictive models will likely be improved if they are specific to the site and birch species measured.
|
|
| 15. |
- Kumar, Anuj, et al.
(författare)
-
Forest Biomass Availability and Utilization Potential in Sweden : A Review
- 2021
-
Ingår i: Waste and Biomass Valorization. - : Springer. - 1877-2641 .- 1877-265X. ; 12:1, s. 65-80
-
Forskningsöversikt (refereegranskat)abstract
- In recent years, there has been a growing interest in many parts of the world for more effective biomass utilization due to legislative and public interest in sustainable development. Whilst much of the effort has been on energy generation from biomass, there is considerable interest on biomass availability and utilization for other end uses. With about 1% of the world’s commercial forest areas, Sweden provides about 10% of the sawnwood, and pulp and paper that is traded on the global market. The Swedish agricultural sector also contributes to biomass availability, not only by production of sustainable food crops, but also by utilizing side streams and underutilized land for biomaterial purposes. To meet the challenges that climate change presents, there has to be a shift to sustainable biomass production and increased interest in promoting a circular bioeconomy. This review presents a systematic assessment on the availability of biomass and its utilization potential in Sweden. The review also focuses on biomass production and trade in the Swedish forest industry. In addition, the environmental impact of biomass utilization is discussed.
|
|
| 16. |
- Renström, Anna, et al.
(författare)
-
The effect of nitrogen source and levels on hybrid aspen tree physiology and wood formation
- 2024
-
Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 176:1
-
Tidskriftsartikel (refereegranskat)abstract
- Nitrogen can be taken up by trees in the form of nitrate, ammonium and amino acids, but the influence of the different forms on tree growth and development is poorly understood in angiosperm species like Populus. We studied the effects of both organic and inorganic forms of nitrogen on growth and wood formation of hybrid aspen trees in experimental conditions that allowed growth under four distinct steady-state nitrogen levels. Increased nitrogen availability had a positive influence on biomass accumulation and the radial dimensions of both xylem vessels and fibers, and a negative influence on wood density. An optimal level of nitrogen availability was identified where increases in biomass accumulation outweighed decreases in wood density. None of these responses depended on the source of nitrogen except for shoot biomass accumulation, which was stimulated more by treatments complemented with nitrate than by ammonium alone or the organic source arginine. The most striking difference between the nitrogen sources was the effect on lignin composition, whereby the abundance of H-type lignin increased only in the presence of nitrate. The differential effect of nitrate is possibly related to the well-known role of nitrate as a signaling compound. RNA-sequencing revealed that while the lignin-biosynthetic genes did not significantly (FDR <0.01) respond to added NO3- , the expression of several laccases, catalysing lignin polymerization, was dependent on N-availability. These results reveal a unique role of nitrate in wood formation and contribute to the knowledge basis for decision-making in utilizing hybrid aspen as a bioresource.
|
|
| 17. |
- Stading, Mats, 1962
(författare)
-
Physical properties of a model set of solid, texture-modified foods
- 2021
-
Ingår i: Journal of Texture Studies. - : Wiley. - 1745-4603 .- 0022-4901. ; 52:5-6, s. 578-586
-
Tidskriftsartikel (refereegranskat)abstract
- Those suffering from swallowing disorders, or dysphagia, require texture-modified foods for safe swallowing. The texture is modified according to the severity of the disorder, as maintained by the guidelines outlining classes of texture-modified foods, ranging from viscous soups to soft, solid foods. As a basis for studies of bolus rheology and oral response of solid texture-modified foods, a set of well-defined, solid foods has been identified and characterized regarding texture and physical properties. Gelled food is compared to both the firmer timbale class and to the corresponding regular food. Foods eaten at room temperature were chosen to avoid temperature effects: bread, cheese, tomato, and the combination into a sandwich. All foods were tested as gel, timbale, and regular food. The texture was determined by compression and penetration tests, thereby showing a decrease in strength (compression stress), stiffness (modulus), and penetration force for increased degree of modification. The moisture content increased with increased degree of modification. The structural change from room to oral temperature was monitored by the complex shear modulus that showed a decrease with increasing temperature. Cheese and the gelatine-based tomato gel showed a distinct melting when the temperature was increased to 37 degrees C. The texture-modified foods were softer and moister in all aspects as compared to the regular foods, which follows the intended modification. The classes for the texture-modified foods were qualitatively comparable to other national classification systems with regard to solid foods, but there is a lack of objective, physics-based classification of texture, especially for solid, texture-modified foods.
|
|
| 18. |
- Abdel Hady, Ahmed Wagih Abdallah, 1990, et al.
(författare)
-
In situ microstructural evolution of spruce wood during soda pulping using synchrotron X-ray tomography
- 2022
-
Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 1437-434X .- 0018-3830. ; 76:7, s. 611-621
-
Tidskriftsartikel (refereegranskat)abstract
- A new laboratory reactor to perform in situ studies of structural changes in wood during soda pulping using synchrotron X-ray tomography is presented. The reactor is of recirculation type to provide stable reaction conditions and mimic the industrial situation. Experiments have been performed using this reactor in situ at a synchrotron microtomography beamline to provide sequences of 3D images from which measurement of wood cell wall thickness have been possible for the first time. The results showed that the cell wall thickness increased significantly in the early stage of pulping (<10 min), which is due to the transportation of cooking chemicals through the tracheids, resin channels and pits into the cell wall, which is swollen with the increased pH. Subsequently, the cell wall thickness reduces over the processing time up to 60 min with a high rate, which is inferred to be due to the dissolution and transport of lignin and hemicellulose from the secondary walls, allowing for better transportation of active chemicals deep through the cell wall layers. After 60 min processing, the cell wall thickness reduction rate reduced, as dissolution of lignin and hemicelluloses from the cell walls ceased, while the remaining dissolution occurs mainly at the middle lamella.
|
|
| 19. |
- Abdel Hady, Ahmed Wagih Abdallah, 1990, et al.
(författare)
-
Micro/nano-structural evolution in spruce wood during soda pulping
- 2021
-
Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 1437-434X .- 0018-3830. ; 75:8, s. 754-764
-
Tidskriftsartikel (refereegranskat)abstract
- Alkaline delignification of wood tissue is the core of the global pulping technology and the most prominent large-scale separation of the main wood components. This work aims at improved understanding of the interplay between the topochemistry of alkaline pulping and the associated morphological changes. Morphology and chemical structure of partially soda-delignified wood chips were studied combining X-ray tomography (XRT), X-ray diffraction analysis and compositional characterization (lignin and carbohydrate content). The XRT studies of wet samples (providing 3D structural information without interfering drying effects), allowed observation of the cell wall separation as an increasing amount of lignin was removed with the increasing pulping time. Comparison between the microstructure of the surface and the central parts of the treated chips showed a more delignified microstructure at the surface, which highlights the dependence of the delignification process on the mass transport (hydroxide ions and lignin fragments) through the wood tissue. The crystallite size of cellulose increased in the <200> crystal planes during the early stage of pulping while there was little effect on the <110> plane.
|
|
| 20. |
- Abdeljaber, Osama, et al.
(författare)
-
Automatic estimation of annual ring profiles in Norway spruce timber boards using optical scanning and deep learning
- 2023
-
Ingår i: Computers & structures. - : Elsevier. - 0045-7949 .- 1879-2243. ; 275
-
Tidskriftsartikel (refereegranskat)abstract
- In softwood species, annual ring width correlates with various timber characteristics, including the density and modulus of elasticity along with bending and tensile strengths. Knowledge of annual ring profiles may contribute to more accurate machine strength grading of sawn timber. This paper proposes a fast and accurate method for automatic estimation of ring profiles along timber boards on the basis of optical scanning. The method utilizes two 1D convolutional neural networks to determine the pith location and detect the surface annual rings at multiple cross-sections along the scanned board. The automatically extracted rings and pith information can then be used to estimate the annual ring profile at each cross-section. The proposed method was validated on a large number of board cross-sections for which the pith locations and radial ring width profiles had been determined manually. The paper also investigates the potential of using the automatically estimated average ring width as an indicating property in machine strength grading of sawn timber. The results indicated that combining the automatically estimated ring width with other prediction variables can improve the accuracy of bending and tensile strength predictions, especially when the grading is based only on information extracted from optical and laser scanning data.(C) 2022 The Author(s). Published by Elsevier Ltd.
|
|
| 21. |
- Abdulgadir, Alamin, et al.
(författare)
-
Performance Simulation of a Composite Filter Material Containing Mechanical Pulp Fibers, Microfibrillated Cellulose, and Cellulose Nanofibers
- 2022
-
Ingår i: Proceedings of the International Mechanical Pulping Conference. ; , s. 160-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Nonwoven fibrous materials with reticular support of an interconnected fiber network and a tortuous airflow pathway have been commonly used in filtration applications. To meet the criteria of filter efficiency and performance, the filter materials are recommended to contain different types of fibers such as mechanical pulp fibers, microfibrillated cellulose, cellulose nanofibers, and other polymer or synthetic fibers with a range of dimensions, i.e., length and diameter. Cellulose fibers in filter media possess irregular and complex structures with hollow or collapsed lumen structures owing to their refinement or pulping method. The development of an appropriate filter media model requires information on actual fiber characteristics. In this study, a simulation method was used to investigate the complex microstructures of filter media. The physical parameters such as fiber wall thickness, diameter, length, cross-section shapes, and curliness were obtained from fiber analyzers and scanning electron microscopy. Based on the experimental findings, GeoDict database comprising different types of common fiber models was constructed. 3-Dimensional fibrous models corresponding to the wet-laid binderless filter material were generated. Using the GeoDict modules, the pore size distributions, average pore sizes, air permeability, pressure drop and initial filter efficiency simulations were performed. The simulation results appear to be in close agreement with the experimental results. The incorporation of cellulose nanofibers resulted in reduced average pore sizes and air permeability of the filter material, thus enhancing the initial filter efficiency. The filter media developed a biobased material derived from pulp fibers for advanced applications such as medical facemask, and air filtration purposes.
|
|
| 22. |
- Abreu, Ilka, et al.
(författare)
-
A metabolite roadmap of the wood-forming tissue in Populus tremula
- 2020
-
Ingår i: New Phytologist. - : John Wiley & Sons. - 0028-646X .- 1469-8137. ; 228:5, s. 1559-1572
-
Tidskriftsartikel (refereegranskat)abstract
- Wood, or secondary xylem, is the product of xylogenesis, a developmental process that begins with the proliferation of cambial derivatives and ends with mature xylem fibers and vessels with lignified secondary cell walls. Fully mature xylem has undergone a series of cellular processes, including cell division, cell expansion, secondary wall formation, lignification and programmed cell death. A complex network of interactions between transcriptional regulators and signal transduction pathways controls wood formation. However, the role of metabolites during this developmental process has not been comprehensively characterized. To evaluate the role of metabolites during wood formation, we performed a high spatial resolution metabolomics study of the wood-forming zone of Populus tremula, including laser dissected aspen ray and fiber cells. We show that metabolites show specific patterns within the wood-forming zone, following the differentiation process from cell division to cell death. The data from profiled laser dissected aspen ray and fiber cells suggests that these two cell types host distinctly different metabolic processes. Furthermore, by integrating previously published transcriptomic and proteomic profiles generated from the same trees, we provide an integrative picture of molecular processes, for example, deamination of phenylalanine during lignification is of critical importance for nitrogen metabolism during wood formation.
|
|
| 23. |
- Adamopoulos, Stergios
(författare)
-
Acoustic emission monitoring of wood materials and timber structures: A critical review
- 2022
-
Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618. ; 350
-
Forskningsöversikt (refereegranskat)abstract
- The growing interest in timber construction and using more wood for civil engineering applications has given highlighted importance of developing non-destructive evaluation (NDE) methods for structural health monitoring and quality control of wooden construction. This study, critically reviews the acoustic emission (AE) method and its applications in the wood and timber industry. Various other NDE methods for wood monitoring such as infrared spectroscopy, stress wave, guided wave propagation, X-ray computed tomography and thermography are also included. The concept and experimentation of AE are explained, and the impact of wood properties on AE signal velocity and energy attenuation is discussed. The state-of-the-art AE monitoring of wood and timber structures is organized into six applications: (1) wood machining monitoring; (2) wood drying; (3) wood fracture; (4) timber structural health monitoring; (5) termite infestation monitoring; and (6) quality control. For each application, the opportunities that the AE method offers for in-situ monitoring or smart assessment of wood-based materials are discussed, and the challenges and direction for future research are critically outlined. Overall, compared with structural health monitoring of other materials, less attention has been paid to data-driven methods and machine learning applied to AE monitoring of wood and timber. In addition, most studies have focused on extracting simple time-domain features, whereas there is a gap in using sophisticated signal processing and feature engineering techniques. Future research should explore the sensor fusion for monitoring full-scale timber buildings and structures and focus on applying AE to large-size structures containing defects. Moreover, the effectiveness of AE methods used for wood composites and mass timber structures should be further studied.
|
|
| 24. |
- Afshar, Reza, et al.
(författare)
-
Creep in oak material from the Vasa ship: : verification of linear viscoelasticity and identification of stress thresholds
- 2020
-
Ingår i: European Journal of Wood and Wood Products. - : Springer Nature. - 0018-3768 .- 1436-736X. ; 78:6, s. 1095-1103
-
Tidskriftsartikel (refereegranskat)abstract
- Creep deformation is a general problem for large wooden structures, and in particular for shipwrecks in museums. In this study, experimental creep data on the wooden cubic samples from the Vasa ship have been analysed to confrm the linearity of the viscoelastic response in the directions where creep was detectable (T and R directions). Isochronous stress–strain curves were derived for relevant uniaxial compressive stresses within reasonable time spans. These curves and the associated creep compliance values justify that it is reasonable to assume a linear viscoelastic behaviour within the tested ranges, given the high degree of general variability. Furthermore, the creep curves were ftted with a one-dimensional standard linear solid model, and although the rheological parameters show a fair amount of scatter, they are candidates as input parameters in a numerical model to predict creep deformations. The isochronous stress–strain relationships were used to defne a creep threshold stress below which only negligible creep is expected. These thresholds ranges were 0.3–0.5 MPa in the R direction and 0.05–0.2 MPa in the T direction.
|
|
| 25. |
|
|
