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  • 1. Ahmed, Sheikh Ali
    et al.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Uneven distribution of preservative in kiln-dried sapwood lumber of Scots pine: Impact of wood structure and resin allocation2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, no 2, p. 251-258Article in journal (Refereed)
    Abstract [en]

    Scots pine (Pinus sylvestris L.) sapwood lumber was collected after kiln drying and preservative treatment with Celcure AC 800 (a copper-amine wood preservative). Distribution of the preservative throughout the lumber was visually examined. Not all, but some samples showed specific localized areas without any preservative distribution throughout their entire length. Those samples were assessed further for anatomical properties, specifically in impregnated and unimpregnated areas. Additional study was conducted on the morphological nature and redistribution of lipophilic extractives using three different histochemical staining methods. Intrinsic wood properties – especially the frequency of axial resin canals and the percentage of canals blocked – were found to be responsible for the irregular distribution of the preservative. Furthermore, the inability to create continuous and frequent interstitial spaces due to the collapse of thin-walled ray cells throughout the lumber resulted in uneven distribution of preservatives. Staining techniques were useful to localize places with more or less abundance of extractives (e.g., fats) in impregnated and unimpregnated wood, which varied considerably. Histochemical observations revealed information pertaining to the kiln dry specific distribution and redistribution of extractives between the areas. Moreover, resin reallocation and modification in ray parenchyma and resin canals induced by kiln drying would be another reason for the impregnation anomalies.

  • 2.
    Bandura, Iryna
    et al.
    Tavria State Agrotechnological University, Department of technology of processi ng and storage of agricultural products.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Assessment of Raw Plant material and Substrate for Efficient production of Oyster Mushrooms (Pleurotusostreatus (Jacq.) P. Kumm.)2016In: Ochrana drevín a dreva 2016: zborník recenzovaných vedeckých prác a abstraktov / [ed] Pavol Hlaváč , Zuzana Vidholdová, Zvolen: Technická univerzita vo Zvolene , 2016, p. 27-33Conference paper (Refereed)
    Abstract [en]

    Microbial analysis of raw materials and substrate during all phases of thermal processing revealed the most efficient methods for industrial mushroom cultivation. The aerobic fermentation in the upper layer is preferable if using long term stored material. The oyster mushroom strain HK-35 was used for testing. An increase in biological efficiency with 37% was found for aerobic fermentation in comparison with stream processing. From evaluation of temperature influence during pasteurization phase, the biological efficiency increased with 11% for tested temperature treatment at 74±3°С in comparison to the standard at 63±3°С.

  • 3.
    Bandura, Iryna
    et al.
    Tavria State Agrotechnological University .
    Myronycheva, Olena
    Tavria State Agrotechnological University .
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Anike, F.N.
    North Carolina A&T State University, Greensboro.
    Isikhuemhen, O.S.
    North Carolina A&T State University, Greensboro.
    Pretreatment of wheat straw and solid state fermentation improves yield and biological efficiency in Pleurotus ostreatus Jacq) P. Kumm. mushroom production2017In: Advances in medicinal mushroom science: Building bridges between Western and Eastern medicine : th International medicinal mushrooms conference : book of abstracts / [ed] Maria Letizia Gardano, Giuseppe Venturella, Palermo, Italy: University of Palermo , 2017, p. 41-43Conference paper (Refereed)
    Abstract [en]

    The pretreatment method for generating substrate for large scale production of oyster mushroom is critical for determining high yield and biological efficiency (BE). The aim of this study was to develop an optimal storage and pretreatment procedure for substrate used in oyster mushroom production. The effect of wheat straw substrate storage (outdoor- open air versus indoor- closed barn) and pretreatment (steam (SP) and hot water (HWP) pasteurization and solid state fermentation (SSF)) on substrate microbiological quality, mushroom yield/BE were investigated during the cultivation of Pleurotus ostreatus strain HK-35. The influence of temperatures used during solid state fermentation on BE was also investigated. There were significant changes among the parameters measured (moisture, total nitrogen, ash content, C/N ratio and total microbial count (CFU) between indoor and outdoor storage. The indoor storage gave higher values. With outdoor storage, CFU showed about 800 times increase. Among the substrate treatment methodstested (SP-control, HWP and SSF), SSF gave consistently higher fruit body yield and BE which ranged from 77-86% compared to the control which ranged from 40-53%. Also SSF conducted at higher temperature (74°C) gave higher BE of 81.2% compared to one conducted at lower temperature (63°C), which gave BE of 69.4%. We consider these findings to be useful in further studies on the redesign oF industrial production systems, which can make oyster mushroom production more profitable in Ukraine and beyond.

  • 4.
    Brunow, G.
    et al.
    University of Helsinki.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lundquist, K.
    Chalmers University of Technology.
    Sipilä, J.
    University of Helsinki.
    On the distribution of the diastereomers of the structural elements in lignins: the steric course of reactions mimicking lignin biosynthesis1993In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 27, no 4, p. 281-286Article in journal (Refereed)
    Abstract [en]

    Stereochemical studies on the formation of the diastereomers of arylglycerol-β-aryl ether structures during lignin biosynthesis have been carried out with model compounds. The addition of water to quinone methides of the β-syringyl ether type gives arylglycerol β-syringyl ethers with a predominance of the erythro isomer when the pH of the medium is low. Since erythro forms of arylglycerol β-syringyl ethers are prevalent in hardwood lignins, this indicates that the pH of the medium in which lignin biosynthesis occurs is lower than has been assumed until now. Equilibration studies with non-phenolic model compounds of the arylglycerolβ-guaiacyl ether and β-syringyl ether types under acidolysis conditions indicate that the erythro predominance observed in the syringyl ethers in lignins does not correspond to equilibrium conditions. A remarkable resistance to acidolysis is observed in the model compounds of etherified syringylglycerol β-syringyl ether type.

  • 5.
    Chen, Tingjie
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wu, Zhenzeng
    College of Material Engineering, Fujian Agricultural and Forestry University.
    Wei, Wei
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Xie, Yongqun
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Wei, Qihua
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Wang, Alice
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Optimizing Refining Conditions of Pinus massoniana Cellulose Fibers for Improving the Mechanical Properties of Ultra-Low Density Plant Fiber  Composite (ULD_UFC)2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 1, p. 8-18Article in journal (Refereed)
    Abstract [en]

    Response surface methodology was used to optimize the refining conditions of Pinus massoniana cellulose fiber and to improve the mechanical properties of ultra-low density plant fiber composite (ULD_PFC). The effects and interactions of the pulp consistency (X1), the number of passes (X2), and the beating gap (X3) on the internal bond strength of ULD_PFC were investigated. The results showed that the optimum internal bond strength (91.72 ± 2.28 kPa) was obtained under the conditions of 8.0% pulp consistency, two passes through the refiner, and a 30.0 μm beating gap. Analysis of the physical properties of the fibers and handsheets showed that the fibrillation of fibers with optimum refining conditions was improved. Also, the tear index of the optimal specimen was 13.9% and 24.5% higher than specimen-1 with a lowest beating degree of 24 oSR and specimen-6 with a highest beating degree of 73 oSR, respectively. Consequently, the optimal refining conditions of the fibers are valid for preparing ULD_PFCs.

  • 6.
    Chen, Tingjie
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. tingjie.chen@ltu.se .
    Xie, Yongqun
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Wei, Qihua
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Wang, Alice
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Liu, Jinghong
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Effect of Refining on Physical Properties and Paper Strength of Pinus massoniana and China Fir Cellulose Fibers2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 3, p. 7839-7848Article in journal (Refereed)
    Abstract [en]

    To obtain a suitable refining process for Pinus massoniana cellulose fibers (PMCF) and China fir cellulose fibers (CFCF), the effects of the beating gap and the pulp consistency on the physical properties and the morphology of the two cellulose fibers were investigated. The results showed that the physical properties of the PMCF and the CFCF were well affected by the beating gap and the pulp consistency. The CFCF showed a smaller weight-average length and width than that of the PMCF. The CFCF exhibited smaller weight-average length, width, and kink index than the PMCF. It is easy to get the high beating degree, indicating it is more easily to be refined. Additionally, the tensile index and burst index of PMCFP and CFCFP increased with increasing beating degree, while the tear index decreased. Compared to the CFCF, the paper made from PMCF had superior strength properties. Consequently, the PMCF was suitable for refining with a high pulp consistency and a medium beating gap, whereas the CFCF had a medium pulp consistency and a big beating gap.

  • 7.
    Chen, Tingjie
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Xie, Yongqun
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Wei, Qihua
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Wang, Xiaodong (Alice)
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Liu, Jinghong
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Lin, Ming
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Improving the Mechanical Properties of Ultra-Low Density Plant Fiber Composite (ULD_PFC) by Refining Treatment2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 4, p. 8558-8569Article in journal (Refereed)
    Abstract [en]

    To improve the mechanical properties of ultra-low density plant fiber composite (ULD_PFC), a suitable beating process to improve the fibrillation of cellulose fibers and maintain their length was investigated. The physical properties of cellulose fibers and papers, surface chemical bonds, and internal bond strength (IB) of ULD_PFCs were analyzed. The results showed that the beating degrees, degree of fibrillation, and fiber fines increased with the decreasing of beating gap, except for the fiber weight-average length, width, kink index, and curl index. The tensile index and burst index of paper showed an increasing trend with an increase in beating degree, while the tear index showed a decreasing trend. FTIR results showed that intermolecular and intramolecular hydrogen bonds in ULDF were broken. A suitable beating gap of 30 μm with a beating degree of 35 °SR was obtained. The corresponding IB was 50.9 kPa, which represented an increase of 73.1% over fibers with a beating degree of 13 °SR.

  • 8. Cristescu, Carmen
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Changes in content of furfurals and phenols in self-bonded laminated boards2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 3, p. 4056-4071Article in journal (Refereed)
    Abstract [en]

    Pressing beech veneers at high temperatures has been shown to be a reliable method for manufacturing laminated boards without adhesives. The reasons behind the self-bonding phenomenon as well as the causes of the waterproof character gained by the boards being pressed at 250 degrees C were investigated. Water leachates from the dried and the hot-pressed veneers were analysed by UV-spectroscopy, high-performance liquid chromatography (HPLC), and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR). Press-plate temperatures during hot pressing were 200, 225, and 250 degrees C. After pressing, an increased content of 5-(hydroxymethyl) furfural (not at 250 degrees C) and conjugated phenols was observed in the bonding lines (interfaces) compared to the inner part of veneers of the self-bonded boards. Furfural contents were low and relatively similar, but 5-(hydroxymethyl) furfural (HMF) showed an abrupt decrease in the bonding line when the temperature increased from 200 degrees C to 225 degrees C and especially to 250 degrees C. The contribution of caramelization to browning and bonding is suggested. In studies with CP/MAS 13C NMR, a higher content of phenolic units in beech lignin was observed during hot pressing at 225 degrees C. Homolytical cleavage of beta-O-4 structures in lignin as well as the condensation reactions involved are discussed

  • 9.
    Cristescu, Carmen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ekevad, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Influence of pressing parameters on mechanical and physical properties of self-bonded laminated beech boards2015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 2, p. 205-214Article in journal (Refereed)
  • 10.
    Cristescu, Carmen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Could colour predict hardness of hot-ptressed self-laminated beech boards2015In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, no 4, p. 150-156Article in journal (Refereed)
    Abstract [en]

    Laminated self-bonded densified boards were obtained by pressing five veneers of beech(Fagus sylvatica L.) parallel-grain-oriented, without adhesive and without surface activation. Theboards were pressed according to an experimental design based on fifteen different combinations ofpressing parameters: temperature (200, 225, and 250°C), pressure (4, 5, and 6MPa), and time (240,300, and 360s). The image of the 40 board edges (radial sections) was analysed with ImageJ softwarein the red-green-blue (RGB) colour space. Brinell hardness tests were also performed. The resultsshow an almost linear relation between the brightness values (defined as the arithmetic mean of theRGB channels) and the Brinell hardness. It is suggested that brightness is a predictor of strength forself-bonded laminated boards.

  • 11.
    Cristescu, Carmen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Markers of quality in self-bonded beech boards2017Conference paper (Refereed)
    Abstract [en]

    A self-bonding phenomenon takes place when five layers of beech (Fagus SylvaticaL.) veneers are pressed at temperatures higher than 200ºC. If the pressing temperature between veneer surfaces reaches at least 225ºC during pressing and if the pressure applied is optimal, water-resistant bonds are formed between veneers. This study investigates the relation of thickness reduction (marker of compression) and mass loss (marker of heat treatment intensity) to boards quality. The effect of water and water vapour on the bondings between veneer in boards pressed at 200, 225 and 250ºC is studied. The conclusion is that pressing 5 layers of 2 mm rotary-cut beech veneer parallel-fibered at 225ºC, 5 MPa and 300 s leads to a thickness reduction of 33.4 % and mass loss of 1.23 %; in such boards bondings are not resistant to liquid water but are resistant to vapour after one adsorption-desorption cycle. When pressing at 250ºC, 5 MPa and 300 seconds, the thickness reduction is 50% and the mass loss 4%; in such boards no delamination was observed when soaked in water. Boards pressed athigher temperature show lower hygroscopicity. Their equilibrium moisture content (EMC) rangedbetween 3.6 and 7%. Based on the results of this study it ishypothesised that the decay resistance of self-bonded boards will increase when increasing the severity of the hot-pressing.

  • 12.
    Dagbro, Ola
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Torniainen, Petteri
    Department of Forest Products, Swedish University of Agricultural Sciences, Uppsala.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Colour responses from wood, thermally modified in superheated steam and pressurized steam atmospheres2010In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, no 3, p. 211-219Article in journal (Refereed)
    Abstract [en]

    In this study, two different methods were used to produce thermally modified wood. One was carried out in a typical kiln drying chamber using superheated steam (SS) and the other used pressurized steam in an autoclave cylinder (PS). Overall, both processes followed the same principles and the wood was not treated with any chemicals. Two wood species were studied, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Treatments in the autoclave were carried out under pressure using temperatures of 160°C, 170°C and 180°C. Temperatures of 190°C and 212°C were used in treatments in the chamber at normal air pressure. The colour was measured using L*C*H colour space. Results for both species showed that similar L* (lightness) can be reached at lower (20-308C) temperatures using PS compared with SS treatment. The hue angle of PS-treated wood was smaller than that of SS-treated wood. No significant difference in C* (chroma) was detected. The difference in E value between PS- and SS-treated wood was smaller for Norway spruce than for Scots pine. The residual moisture content was about 10% higher in wood treated by the PS process compared with the SS process

  • 13.
    Elustondo, Diego
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Localized Wood Surface Modification: Part I: Method Characterization2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 1, p. 283-295Article in journal (Refereed)
    Abstract [en]

    This study assesses the potential of an open process for treatment of European Scots pine (Pinus sylvestris) with chemicals that could potentially make the surfaces stronger, more dimensionally stable, or more durable, depending on the treatment solution. The method provides an intermediate solution between full volume impregnation by pressure treatment and superficial surface treatment by dipping. Figuratively speaking, the process creates the equivalent of a layer of coating applied below the wood surfaces rather than above. Two different techniques were compared, namely, heating-and-cooling (H&C) and compression-and-expansion (C&E). Taking into account that commercial suppliers recommend 0.15 to 0.25 L/m2 of coating in sawn wood and 0.1 to 0.15 L/m2 in planed wood surfaces, then this study demonstrates that the H&C method can impregnate an equivalent amount of solution under the surfaces in less than 15 min using treatment temperatures below 150 °C.

  • 14.
    Elustondo, Diego
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sidorova, Ekaterina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Development of method for surface modification of wood.2015In: Proceedings of the Eighth European Conference on Wood Modification: ECWM8 / [ed] Mark Huges; Lauri Rautkari; Tuuli Uimonen; Holger Militz; Brigitte Junge, Helsinki: Aalto University, School of Chemical Engineering , 2015, p. 137-140Conference paper (Refereed)
  • 15.
    Hemmilä, Venla
    et al.
    Department of Forestry and Wood Technology, Linnaeus University.
    Adamopoulos, Stergios
    Department of Forestry and Wood Technology, Linnaeus University.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kumar, Anuj
    Department of Forestry and Wood Technology, Linnaeus University.
    Development of sustainable bio-adhesives for engineered wood panels: A Review2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 61, p. 38604-38630Article in journal (Refereed)
    Abstract [en]

    Changes in both formaldehyde legislations and voluntary requirements (e.g. Germany RAL) are currently the driving factors behind research on alternatives to amino-based adhesives; moreover, consumer interest in healthy and sustainable products is increasing in bio-based adhesives. Sources of formaldehyde emissions in wood-based panels as well as different emission test methods have been discussed, and the main focus of this review is on the research conducted on sustainable bio-based adhesive systems for wood panels. Lignin, tannin, protein, and starch have been evaluated as both raw materials and adhesive alternatives to existing amino-based thermosetting adhesives. Adhesion improving modifications of these bio-based raw materials as well as the available and experimental crosslinkers have also been taken into account.

  • 16.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Modified Wood-Protein Adhesive Bondline Strength Development during Curing2014In: The seventh European Conference on Wood Modification: Book of Abstracts / [ed] Lina Nunes; Dennis Jones; Callum Hill; Holger Militz, Lissabon, 2014, p. 134-137Conference paper (Refereed)
  • 17. Jönsson, L.
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lundquist, K.
    Nyman, P. O.
    Trametes versicolor ligninase: isozyme sequence homology and substrate specificity1989In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 247, no 1, p. 143-146Article in journal (Refereed)
    Abstract [en]

    The substrate specificity of three ligninase isozymes from the white-rot fungus Trametes versicolor has been investigated using stereochemically defined synthetic dimeric models for lignin. The isozymes have been found to attack non-phenolic β-O-4 as well as β-1 lignin model compounds. This finding confirms the classification of the isozymes from T. versicolor as ligninases. The amino-terminal residues of the three isozymes from T. versicolor have been determined using Edman degradation. Minor differences found between the sequences suggest the existence of several structural genes for ligninase in T. versicolor. Comparisons have been made with the sequences of three previously reported ligninases from Phanerochaete chrysosporium, another lignin-degrading fungus. One of the sequences from P. chrysosporium is distinctly more similar to the T. versicolor isozymes than to the other two sequences from P. chrysosporium.

  • 18.
    Jönsson, L.
    et al.
    University of Lund.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lundquist, K.
    Chalmers University of Technology.
    O., Nyman P.
    University of Lund.
    Stereospecificity in enzymic and nonenzymic oxidation of b-O-4 lignin model compounds1990In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 276, no 1,2, p. 45-48Article in journal (Refereed)
  • 19.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cristescu, Carmen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Neyses, Benedikt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Pretreatment of veneers with hydrogen peroxide for self-bonded laminated boards.2015In: Proceedings of the Eighth European Conference on Wood Modification: ECWM8 / [ed] mark Huges; Lauri Rautkari; Tuuli Uimonen; Holger Militz; Brigitte Junge, Helsinki: Aalto University, School of Chemical Engineering , 2015, p. 305-310Conference paper (Refereed)
  • 20.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cristescu, Carmen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Autoadhesion of laminated boards from Scots pine veneers: effect of oxidative pretreatment2015In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, no 4, p. 110-115Article in journal (Refereed)
    Abstract [en]

    This paper presents results from studies on the pre-treatment of veneers from Scots pineusing hydrogen peroxide and a ferrous catalyst followed by pressing at 220, 230, and 240°C. Thetreatment gave boards that did not delaminate when exposed to water followed by drying of roomtemperature, whereas boards without a pre-treatment delaminated. The press-plate temperature didnot influence the extent of delamination, but the thickness swelling was lower at higher presstemperature. Analysis of extracts from the oxidative pre-treated and hot-pressed surface materialusing UV-spectroscopy was compared with analysis of bondlines from water-stable laminated boardsfrom beech.

  • 21.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Dagbro, Ola
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Granlund, Kurt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Soluble degradation products in thermally modified wood2014In: Final Cost Action FP0904 Conference: “Recent Advances in the Field of TH and THM Wood Treatment” : May 19-21, 2014, Skellefteå, Sweden : book of abstracts / [ed] Mojgan Vaziri; Dick Sandberg, Skellefteå: Luleå tekniska universitet, 2014, p. 16-17Conference paper (Refereed)
  • 22.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ikeda, Tsutomu
    Wood Chemistry Laboratory.
    Kishimoto, Takao
    Wood Chemistry Laboratory.
    Magara, Kengo
    Wood Chemistry Laboratory.
    Matsumoto, Yuji
    Wood Chemistry Laboratory.
    Hosoya, Shuji
    Wood Chemistry Laboratory.
    Isolation of lignin-carbohydrate bonds in wood: model experiments and preliminary application to pine wood2004In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 50, no 2, p. 141-150Article in journal (Refereed)
    Abstract [en]

    A novel method for analysis of benzylic ether type lignin-carbohydrate bonds has been developed by using model compounds. Four diastereomers of model compound 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-3-(methyl -d-glucopyranoside-6-O-yl)-1-propanol (GGMGP), were ozonized in acetic acid/water/methanol 16:3:1 for 1h at 0°C. The product from ozonation of each diastereomer was saponified and the corresponding -etherified tetronic acid (TAMGP) was isolated using ion exchange chromatography. Minor amounts of methyl -d-glucopyranoside (MGP) and small amounts of a gluconic acid etherified with tetronic acid (TAGLCA), tetronic acid, gluconic acid, and glyceric acid were detected in the product mixture of ozonated benzylic ether type model compounds. The results suggest that a benzyl ether bond between lignin and carbohydrate is rather stable during the ozone treatment. Acid treatments with sulfuric acid or trifluoroacetic acid of the derived TAMGP led to cleavage of the glucosidic bond but only a small amount of products (tetronic acid and glucose) resulting from cleavage of the -ether bond were formed. The successful chemical treatments were used for studies of benzylic ether bonds in Japanese red pine. The results suggest the presence of benzylic ether bonds to polysaccharides in the wood.

  • 23.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ikeda, Tsutomu
    Forestry and Forest Products Research Institute.
    Kishimoto, Takao
    Forestry and Forest Products Research Institute.
    Magara, Kengo
    Forestry and Forest Products Research Institute.
    Matsumoto, Yuji
    Forestry and Forest Products Research Institute.
    Hosoya, Shuji
    Forestry and Forest Products Research Institute.
    Ozonation of a lignin-carbohydrate complex model compound of the benzyl ether type2000In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 46, no 3, p. 263-265Article in journal (Refereed)
    Abstract [en]

    Evidence for the presence of lignin-carbohydrate bonds of the benzylic ether type in wood and pulps may be obtained by use of ozonation treatment to selectively degrade the lignin. It was found that the benzyl ether bond in 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxy-phenoxy)-3-(methyl--d-glucopyranosid-6-O-yl)-1-propanol was rather stable during ozonation in acetic acid-water-methanol 1631 at 0°C. The corresponding acid, 3,4-dihydroxy-2-(methyl--d-glucopyranosid-6-O-yl)-butanoic acid, was found to be the major reaction product. The use of ozonation followed by acid hydrolysis in connection with studies of lignincarbohydrate linkages is briefly discussed.

  • 24.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ikeda, Tsutomu
    Magara, Kengo
    Hosoya, Shuji
    Novel method for isolation of a lignin-carbohydrate bond2001In: 11th ISWPC: Symposium on Wood and Pulping Chemistry; Nice, France, June 11 to 14, 2001, Nice, 2001Conference paper (Refereed)
  • 25.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lundquist, Knut
    Acid reactions of hydrobenzoins: effect of catalyst and reaction medium on product composition1992In: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. 46, p. 283-289Article in journal (Refereed)
  • 26.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lundquist, Knut
    Chalmers University of Technology.
    Stomberg, Rolf
    Chalmers University of Technology.
    Preparation and crystal structure of (+/-)-1,2-Bis(3,4-dimethoxyphenyl)-1,2-ethanediol1993In: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. 47, p. 728-733Article in journal (Refereed)
  • 27.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lundquist, Knut
    Stomberg, Rolf
    Studies on hydrobenzoins: preparation, crystal structure and stability of borate complexes1990In: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. 44, p. 617-624Article in journal (Refereed)
  • 28.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Colour stabilization of heat modified Norway spruce exposed to out-door conditions2010In: Proceedings, 11th International IUFRO Wood Drying Conference: [... in Skellefteå, Sweden, January 18 - 22, 2010 ... the theme of the conference was "Recent Advances in the Field of Wood Drying"] / [ed] Tom Morén; Lena Antti; Margot Sehlstedt-Persson, Luleå: Luleå tekniska universitet, 2010, p. 265-268Conference paper (Refereed)
    Abstract [en]

    Wood boards from Norway spruce (300 mmx125mmx10mm) were heat modified in a pilot chamber corresponding to Thermowood-D quality. The surface of boards was sprayed with diluted solutions of ferrous sulphate alone or in combination with subsequent spraying of a 30% solution of hydrogen peroxide. The boards were exposed to outdoor conditions during summer 2009 (45o facing south). Colour coordinates were measured using a colorimeter.Only small changes in colour of boards were observed directly after the surface treatments. Lightness increased for boards with no surface treatments during out-door exposure (seven weeks). Increase in lightness was delayed when ferrous sulphate was applied to the board. Lightness was essentially unchanged during the out-door exposure period when ferrous sulphate and hydrogen peroxide was used to modify the wood surface (at low hydrogen peroxide charge a small increase of lightness was, however, observed). Chroma decreased for boards with surface treatments but levelled out after a couple of weeks. On the other hand a decrease in chroma of boards with no surface treatments started after about four weeks exposure. Hue increased for all the boards until the fourth week. After that hue of untreated boards and boards treated with both ferrous sulphate and hydrogen peroxide continue to increase.

  • 29.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Elustondo, Diego
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Thermally modified wood treated with methacrylate2018In: Proceedings IRG Annual Meeting IRG49 Scientific Conference on Wood Protection Sandton, Johannesburg, South Africa 29 April-3 May, 2018Conference paper (Refereed)
    Abstract [en]

    Thermally modified timber (TMT)from Scots pine sapwood similar to Thermo-D quality was impregnated with methacrylate resin by the hot-and-cold method and subsequently cured at elevated temperatures. The results showedthat methacrylate resin could be used to reduce colouring of painted TMT wood during accelerated weathering probably by hindering the migration of extractives. The resin itself did not reduce greying of the unpainted wood. Hardness was only slightly improved by treatment with the resin probably due to a higher density of the material. Formation of blisters occurred but wasreduced by treatment with the resin. Resistance to mould growth by a mixture of Aureobasidium pullulans, Cladosporium cladosporioides, Aspergillus versicolor, Penicillium purpurogenumwas performed by applying EN-15457:2014. Treatment with methacrylic resin hindered the colonisation of the three last mouldfungi.

  • 30.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Multivariate modeling of mould growth in relation to extractives in dried Scots pine sapwood2017In: Proceedings IRG Annual Meetin, 2017, article id 17-20629Conference paper (Refereed)
    Abstract [en]

    Influence of extractives on mould growth on Scots pine sapwood dried in air or in kiln was studied. Boards were sprayed with water mixtures of spores of the fungal species Penicillium sp., Aspergillus sp., Mucor sp., Paecilomyces sp., Trichoderma sp., treated at a temperature of 22ºC at 90% RH, classified into a percentage of covered area. Acetone and water extracts were isolated and analyzed for sugars, nitrogen, ash, resin/fatty acids, glycerol, and phenols. A multivariate Orthogonal Partial Least Squares (OPLS) regression model was developed to study relations between the extent of mould coverage of boards and chemical content. The model describes 51% variability in X and 69% in Y with prediction power of 55%. The results indicated that total acetone soluble extractives and sugars like glucose contributed to increased mould growth whereas fatty acids prevent mould growth.

  • 31.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Pettersson, B.
    Westermark, Ulla
    Linkages between residual lignin and carbohydrates in bisulphite (magnefite) pulps2001In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 27, no 9, p. 310-316Article in journal (Refereed)
    Abstract [en]

    The presence of bonds between residual lignin and carbohydrates in bisulphite pulps from hardwoods and softwoods was studied. Results showed that a fraction of the residual lignin was bonded to cellulose in bisulphite pulps of softwood. The treatment with xylanase indicated the existence of alkali-stable lignin-xylan bonds in softwood bisulphite pulps.

  • 32.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Pettersson, B.
    Westermark, Ulla
    The use of cellulases and hemicellulases to study lignin-cellulose as well as lignin-hemicellulose bonds in kraft pulps2001In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 27, no 6, p. 196-201Article in journal (Refereed)
    Abstract [en]

    The combination of carbohydrate-degrading enzymes and size-exclusion chromatography (SEC) has been used to analyze the existence of covalent bonds between lignin and cellulose and/or hemicelluloses in pulps. Cellulases and xylanase were used for degradation of cellulose and xylan, respectively. Analysis of the molecular weight profiles of lignin and carbohydrates before and after enzymic hydrolysis were performed by dissolution of the pulps in LiCl/dimethylacetamide (DMAC). The results indicate that a considerable part of the residual lignin in unbleached pine kraft pulp is bond to cellulose. Bonding of lignin to xylan in the pine kraft pulp could also be detected. Analysis of birch kraft pulp shows that most of the residu lignin in birch kraft pulps is covalently linked to xylan. The combination of carbohydrate-degrading enzymes and SEC in LiCl/DMAC seems to be an excellent way of characterizing bonds between lignin and carbohydrates in chemical pulps.

  • 33.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Yang, Qian
    Heat treatments of high temperature dried norway spruce boards: Saccharides and furfurals in sapwood surfaces2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 2, p. 2284-2299Article in journal (Refereed)
    Abstract [en]

    Carbohydrates that migrate to wood surfaces in sapwood during drying might influence properties such as mould susceptibility and colour. Sugars on the surface of Norway spruce boards during various heat treatments were studied. Samples (350mm×125mm×25mm) were double-stacked, facing sapwood-side outwards, and dried at 110°C to a target moisture content (MC) of 40%. Dried sub-samples (80 mm × 125 mm × 25 mm) were stacked in a similar way and further heated at 110°C and at 130°C for 12, 24, and 36 hours, respectively. Glucose, fructose, and sucrose as well as 5-hydroxymethylfurfural (HMF) and furfural in the sapwood surface layer of treated wood were analysed using HPLC (RI- and UV-detectors). Carbohydrates degraded to a lower extent at 110°C than at 130°C. Furfural and to a larger extent HMF increased with treatment period and temperature. Heat treatment led to a decrease in lightness and hue of the sapwood surface of sub-samples, while chroma increased somewhat. Furthermore, considerably faster degradation (within a few minutes) of the carbohydrates on the surface of the dried spruce boards was observed when single sub-samples were conductively hot pressed at 200°C. Treatment period and initial MC influenced the presence of the carbohydrates in wood surface as well as colour change (ΔE ab) of the hot pressed sub-samples.

  • 34.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sidorova, Ekaterina
    SP Technical Research Institute of Sweden.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Influence of heat transferring media on durability of thermally modified wood2011In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 6, no 1, p. 356-372Article in journal (Refereed)
    Abstract [en]

    Studies on the durability and dimensional stability of a series of hardwoods and softwoods after thermal modification in vegetable oils and in steam atmospheres have been performed. Mass loss after exposure to Coniophora puteana (BAM Ebw. 15) for 16 weeks was very low for European birch, European aspen, Norway spruce, and Scots pine thermally modified in a linseed oil product with preservative (for 1 hour at 200 degrees C). Fairly low mass losses were obtained for wood thermally modified in linseed-, tung-and rapeseed oil, and losses were related to the wood species. Low mass loss during rot test was also found for Norway spruce and Scots pine modified in saturated steam at 180 degrees C. Water absorption of pine and aspen was reduced by the thermal treatments and the extent of reduction was dependent on wood species and thermal modification method. Thermally modified aspen was stable during cycling climate tests, whereas pine showed considerable cracking when modified under superheated steam conditions (Thermo D). At lower modification temperature (180 degrees C) an increase in mass after modification in rapeseed oil of spruce, aspen and sapwood as well as heartwood of pine was observed, whereas at high temperature (240 degrees C) a mass loss could be found. Oil absorption in room tempered oil after thermal modification in oil was high for the more permeable aspen and pine (sapwood).

  • 35.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Torniainen, Petteri
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Dagbro, Ola
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Granlund, Kurt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Presence of water-soluble compounds in thermally modified wood: carbohydrates and furfurals2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 3, p. 3679-3689Article in journal (Refereed)
    Abstract [en]

    With thermal modification, changes in properties of wood, such as the presence of VOC and water-soluble carbohydrates, may occur. Thermal modifications under saturated steam conditions (160°C or 170°C) and superheated steam conditions (170, 185, and 212°C) were investigated by analysing the presence of water-soluble 5-(hydroxymethyl)furfural (HMF), furfural, and carbohydrates in heat-treated wood. The influence of thermal modifications on Scots pine, Norway spruce, and silver birch was also studied. Furfurals were analysed using HPLC at 280 nm, while monosaccharides and water-soluble carbohydrates were determined by GC-FID as their acetylated alditiols and, after methanolysis, as their trimethylsilylated methyl-glycosides, respectively. The amount of furfurals was larger in boards thermally modified under saturated steam conditions than those treated under superheated steam conditions. Generally, more of HMF than furfural was found in the thermally modified boards. In process water, in which saturated steam conditions had been used, furfural and only traces of HMF were found. Higher content of water-soluble carbohydrates was found in boards treated in saturated steam rather than in superheated steam. After modification in saturated steam, substantial parts of the water-soluble carbohydrates were due to monosaccharides, but only traces of monosaccharides were found in boards treated under superheated steam conditions.

  • 36.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Auto-adhesive bonding by oxidative treatment of wood2003In: Proceedings of the 12th International Symposium on Wood and Pulping Chemistry: University of Wisconsin-Madison, Department of Forest Ecology and Management, June 9 - 12, 2003, Madison, Wisconsin, USA, Madison, Wis, 2003, p. 365-368Conference paper (Refereed)
  • 37.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Evidence for chemical bonds between lignin and cellulose in kraft pulps1996In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 22, no 10, p. J397-401Article in journal (Refereed)
    Abstract [en]

    The cellulose solvent system LiCl-dimethylacetamide has been used to dissolve kraft pulps prepared from pine and birch. The dissolved polymers were analyzed using size-exclusion chromatography combined with both RI- and UV-detection systems in order to monitor simultaneously the major wood polymers (cellulose, hemicellulose and lignin). Kraft pulps from birch were completely soluble in the solvent system and the pine kraft pulp about 80% soluble. Analyses of the kraft pulps strongly suggest that a considerable amount of the residual lignin is chemically linked to the high molecular weight cellulose in pine but not in birch. The presence of stable lignin-cellulose bonds will reduce the possibility of achieving a low kappa number by cooking. For comparison, sulphite and bisulphite pulps were also examined. Both pulps were soluble in the solvent system and analyses indicated that lignin-cellulose bonds also exist in these pulps although to a significantly lesser extent than in the pine kraft pulp

  • 38.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Resin-free particleboard by oxidation of wood2002In: 6th Pacific Rim Bio-Based Composites Symposium & Workshop on the Chemical Modification of Cellulosics: November 10th to 13th 2002, Portland, Oregon ; proceedings / [ed] P. E. Humphrey, Corvallis, Or: Wood science and engineering department , 2002Conference paper (Refereed)
  • 39.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    The significance of glucomannan for the condensation of cellulose and lignin under kraft pulping conditions1997In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 12, no 2, p. 90-Article in journal (Refereed)
  • 40.
    Karlsson, Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Backlund, Ulrika
    Metso, Sundsvall.
    Halvarsson, Sören
    Mittuniversitetet.
    Environmentally friendly process for high density fibreboards2006Conference paper (Other academic)
    Abstract [en]

    Urea-formaldehyde (UF) resin is a common binder in many fibre- and particleboards today. However, formaldehyde is a fairly reactive compound with many negative affects on health and environment. This paper describes a process to make thin high density fibreboards without use of conventional resin such as UF. Initially we found that wood particles such as ones used in particle board had, when activated with hydrogen peroxide and iron catalyst, self-bonding capability when hot-pressed into boards. Low swelling board, although at somewhat higher density than conventional glued ones, could be formed by pressing activated wood particles at 170 oC in a laboratory press. We found that the activation technique was applicable to dry or semi-dry board processes and was considered to be well suited for fibreboards from refined wood fibers especially as their specific (contact) area is high. Activated wood fibres were produced at Metso Panelboards Pilot-refiner in Sundsvall and mats were also formed and pressed into boards 50x60 cm2 at fairly conventional pressing conditions. At a hydrogen peroxide charge of 4% boards made from birch fibres with good mechanical properties (in terms of bending strength and internal bonding) were produced. Thickness swelling in water was low (TS24h., 15-20%). At lower hydrogen peroxide charges (<2%) the swelling was higher. Development of the process to also include other wood species than birch is in our interest. Furthermore, properties of the boards were strongly dependent on the moisture content of fibres; at low moisture content (MC<8%) thickness swelling increased. We see a high potential in the process as the glue-free technique is estimated to reduce production cost of boards as well as give environmental advantages.

  • 41.
    Kishimoto, Takao
    et al.
    Forestry and Forest Products Research Institute.
    Ikeda, Tsutomu
    Wood Chemistry Laboratory, Forestry and Forest Products Research Institute, 305-8687 Ibaraki.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Magara, Kendo
    Wood Chemistry Laboratory, Forestry and Forest Products Research Institute, 305-8687 Ibaraki.
    Hosoya, Shuji
    Wood Chemistry Laboratory, Forestry and Forest Products Research Institute, 305-8687 Ibaraki.
    Reactivity of secondary hydroxyl groups in methyl β-D-xylopyranoside toward a β-O-4-type quinone methide2002In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 48, no 1, p. 32-37Article in journal (Refereed)
    Abstract [en]

    Methyl β-D-xylopyranoside was allowed to react with β-O-4-type quinone methide without a catalyst to elucidate the reactivities of secondary hydroxyl groups at the C2, C3, and C4 positions. Benzyl ether-type lignin-carbohydrate complex (LCC) compounds linked at the C2 and C4 positions were predominant, at a ratio of 2:3. However, the reactivity of the hydroxyl group at the C3 position was quite low. These results strongly suggest that the reactivity of the C2 hydroxyl group in xylan toward quinone methide intermediate is higher than that of the C3 hydroxyl group during biosynthesis of LCCs

  • 42. Magara, Kengo
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hosoya, Shuji
    Reduction of chloroform emission from hypochlorite-bleaching process2003In: Kami Pa Gikyoshi, ISSN 0022-815X, Vol. 57, no 9, p. 76-83Article in journal (Refereed)
    Abstract [en]

    Chloroform was readily converted to formic acid through the nucleophilic attack of hydroxyl anion under the certain reaction conditions (pH>12, temp.>°C). When guaiacol was reacted with hypochlorite at such reaction conditions, the generation of chloroform was almost completely reduced. Successful reduction of the chloroform generation was also observed in alkaline hypochlorite bleaching of kraft pulps and DIP without any loss in pulp quality. Even when the hypochlorite bleaching was carried out under the open system (no sealing of the reaction vessel), nearly 90% of the generated chloroform was converted to formic acid.

  • 43.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Bandura, Iryna
    Department of Technology Processing and Storag e of Agricultural Products, Tavria State Agrotecnological University.
    Bisko, Nina
    Department of Mycology, Institute of Botany, National Academy of Sciences of Ukraine.
    Grygansky, Andrii P.
    LF Lambert Spawn Co..
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Assessment of the Growth and Fruiting of 19 Oyster Mushroom Strains for Indoor Cultivation on Lignocellulosic Wastes2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 3, p. 4606-4626Article in journal (Refereed)
    Abstract [en]

    AbstractTwelve Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm and six Pleurotus pulmonarius (Fr.) Quél. strains were characterized from the National Culture Collection of Mushrooms, Institute of Botany Kholodny, National Academy of Science, Kyiv, Ukraine (IBK). The strains were grown under commercial conditions on a mixture of wheat straw and sunflower shells under both winter and summer temperatures typical for those climatic conditions. The strains were divided into three groups according to their growing patterns. Important characteristics were compared with a commercial analogue, HK-35, such as vegetative growth, generative growth, and biological efficiency (1.9- to 3.1-fold), and were recorded for strains 2251, 2292, 2316, 2319, and 2320 of P. ostreatus and 2314 of P. pulmonarius. Strains 2251, 2292, 2301, 2321 and 2323 were the most suitable for commercial production, while strains 2319 and 2320 could satisfy processing industry requirements with their high biological efficiency. Strains 2287 and 2317 produced high-quality fruit bodies but probably required a higher temperature for cultivation. Strain 2318 might be attractive for some consumers due to its unique and unusual fruit body shape. Strain 2314 was the most promising for summer cultivation, while strain 537 produced the highest quality fruit bodies.KeywordsOyster mushroom; Strain; Vegetative growth; Fruit body; Biological efficiency; Conversion Factor (CF); Asymmetry of the Fruit Body Cap (Cas)

  • 44.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sidorova, Ekaterina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hyperspectral Imaging Surface Analysis for Dried and Thermally Modified Wood: An Exploratory Study2018In: Journal of Spectroscopy, ISSN 2314-4920, E-ISSN 2314-4939, article id 7423501Article in journal (Refereed)
    Abstract [en]

    Naturally seasoned, kiln-dried, and thermally modified wood has been studied by hyperspectral near-infrared imaging between 980 and 2500 nm in order to obtain spatial chemical information. Evince software was used to explore, preprocess, and analyse spectral data from image pixels and link these data to chemical information via spectral wavelength assignment. A PCA model showed that regions with high absorbance were related to extractives with phenolic groups and aliphatic hydrocarbons. The sharp wavelength band at 2135 nm was found by multivariate analysis to be useful for multivariate calibration. This peak represents the largest variation that characterizes the knot area and can be related to areas in wood rich in hydrocarbons and phenol, and it can perhaps be used for future calibration of other wood surfaces. The discriminant analysis of thermally treated wood showed the strongest differentiation between the planed and rip-cut wood surfaces and a fairly clear discrimination between the two thermal processes. The wavelength band at 2100 nm showed the greatest difference and may correspond to stretching of C=O-O of polymeric acetyl groups, but this requires confirmation by chemical analysis.

  • 45.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards2018In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 10, article id e0204212Article in journal (Refereed)
    Abstract [en]

    During industrial wood drying, extractives migrate towards the wood surfaces and make the material more susceptible to photo/biodegradation. The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS). The concentration of total extractives was significantly higher in kiln-dried than in air-dried samples and was higher close to the surface than in the layers beneath. The scatter in the values for the lipophilic extractives was high in both drying types, being highest for linoleic acid and slightly lower for palmitic, oleic and stearic acids. The amount of fatty acids was low in kiln-dried boards, probably due to a stronger degradation due to the high temperature employed. The most abundant resin acid was dehydroabietic acid followed by pimaric, isopimaric, and abietic acids in both drying types. It is concluded that during kiln-drying a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm.

  • 46.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Poohphajai, Faksawat
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. innoReNew, Slovenia.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Vikberg, Tommy
    RISE Research Institutes of Sweden, Skellefteå, Sweden.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Junge, Helmut
    ABiTEP GmbH, Berlin, Germany.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Application of GRAS Compounds for the Control of Mould Growth on Scots Pine Sapwood Surfaces: Multivariate Modelling of Mould Grade2019In: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 10, no 9, article id 714Article in journal (Refereed)
    Abstract [en]

    Research Highlights: In this study, the Generally Recognised as Safe (GRAS) compounds were applied in order to study mould-fungi growth on dried Scots pine sapwood. Background and Objectives: The transition to the use of more sustainable wood-material may be possible by applying GRAS compounds that can control and prevent contamination by primary colonising mould fungi. Materials and Methods: Kiln-dried sawn timber was treated with three different GRAS compounds, and different fungal inoculation methods applied in order to investigate differences in the development of fungal communities. Results: Substances based on potassium silicate significantly reduced fungal growth and mould contamination on the studied wood surfaces. By combining wood-surface treatments with GRAS compounds, fungal-area size as predictors and mould grade as response, a partial least squares (PLS) model that makes it possible to predict mould grade on wood surfaces was developed. The PLS model is a key component in the development of a smart grading-systems equipped by e.g. high-speed digital cameras for the early detection of fungal attack on wood surfaces in different applications. However, the measurements based on chemical characterisation should be the next step to take in order significantly to enhance the model and increase the range of robust applications. In the current study, a multivariate model describing the influence of each fungal-covering area on mould grade was presented for the first time.

  • 47.
    Myronycheva, Olena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Growth of mold and rot fungi on copper-impregnated Scots pine sapwood: Influence of planing depth and inoculation pattern.2018In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 4, p. 8787-8801Article in journal (Refereed)
    Abstract [en]

    The biocidal properties of an industrially used copper-based preservative were evaluated at different planing depths on exposure of pine wood to mold fungi in direct and indirect contamination methods, with simultaneous verification of white rot fungi virulence on wood. The preservative was an aqueous solution of copper carbonate, 2-aminoethanol, and quaternary ammonium compounds. Full cell preservative impregnation efficiency against visual mold fungi growth was tested on sapwood surfaces planed to different depths before impregnation. The virulence of two white rot fungal strains of Trametes versicolor (441 and JPEI) against the dried non-impregnated and impregnated wood samples was also tested. The unplaned surface of impregnated timber was occupied by air-borne contaminants, such as Paecilomyces variottiand Aspergillus niger up to 30%, and, even after impregnation it was necessary to process the surface to avoid micro-fungi settlement. The virulence of the tested rot fungi strains was confirmed by the aggressive degradation of non-impregnated wood with a mass loss of over 40%. Both Trametes sp. strains degraded the preservative-impregnated wood with a mass loss of 3.1% to 4.8%, but degradation by the JPEI strain was more intensive and more dependent on planing depth than the other strain (441).

  • 48.
    Niu, Min
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wang, Alice
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Xie, Yongqun
    Fujian Agriculture and Forestry University, Department of Wood Science & Technology.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cai, LiLi
    Fujian Agriculture and Forestry University, Department of Wood Science & Technology.
    Effect of Si-Al compounds on fire properties of ultra-low density fiberboard2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 2, p. 2415-2430Article in journal (Refereed)
    Abstract [en]

    An ultra-low density fiberboard was made of plant fiber using a liquid frothing approach. The inflammability of the plant fiber limited its application as a candidate for building insulation materials and packaging buffering materials. Si-Al compounds were introduced into the foaming system because of the high temperature resistance of Si and Al compounds. The results from energy-dispersive spectroscopy suggested that the Si and Al relatively evenly covered the surface of the fibers, and their weight ratios in the material increased as a function of the amount of Si-Al compounds. The increasing weight ratios of Si and Al affected the fire properties of the material, reducing the released amount of heat, smoke, and off-gases such as CO and CO2, as well as decreasing the mass loss percentage, shown through the use of a Cone Calorimeter. It follows that Si-Al compounds have an evident collaborative effect on the halogen fire retardant. The system can effectively restrain the fire hazard intensity and the yields of solid and gas volatiles.

  • 49.
    Niu, Min
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wang, Xiaodong (Alice)
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Xie, Yongqun
    Fujian Agriculture and Forestry University.
    Microstructure of Burned Ultra-Low-Density Fiberboards using Plant Fiber as the Matrix and Si-Al compounds as the Filler2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 2, p. 2903-2912Article in journal (Refereed)
    Abstract [en]

    Ultra-low-density fiberboards (ULDFs) were prepared by a liquid frothing technique using plant fibers as the matrix and Si-Al compounds as the filler to be used as a versatile bio-based composite. Si-Al compounds played an important role in the fire properties of ULDFs. Fire intensity and the amount of volatiles were significantly restrained because of the Si-Al compounds. To determine the combustion mechanism of ULDFs treated by Si-Al compounds, the microstructure of burned specimens was tested by chemical analysis, X-ray diffractometer (XRD), and infrared spectrometer (IR). According to the results from gas chromatography, glucose, xylose, and mannose disappeared in the bottom ashes. After combustion, the XRD profiles of the two ashes became weaker and broader; the sharpest peaks at 18.6o (2) that represented Si-Al compounds remained; the obvious peaks at 22o (2) from cellulose were gone. The results from IR suggested the characteristic functional groups OH, CH, and C=O from carbohydrate also disappeared, and absorbance at 1200 to 400 cm-1, which attributed to the vibration of Si-O, Al-O, and Si- O-Si bonds, increased. In conclusion, fibers are almost completely pyrolyzed at 780 °C. The crystalline structure of Si-Al compounds is rearranged and more amorphous silicon oxide and aluminum oxide are generated.

  • 50.
    Niu, Min
    et al.
    Fujian Agriculture and Forestry University, Fuzhou, China.
    Wang, Xiaodong (Alice)
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Xie, Yongqun
    Fujian Agriculture and Forestry University.
    Morphology of Burned Ultra-low Density Fiberboards2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 4, p. 7292-7301Article in journal (Refereed)
    Abstract [en]

    The synergistic effect of two fire retardants, a Si-Al compound and chlorinated paraffin, was tested on ultra-low density fiberboards (ULDFs). To further understand the mechanism of fire retardancy, morphologies of unburned and burned ULDFs were studied using a scanning electron microscope with energy dispersive spectroscopy. It was found that as the volume of the burned ULDFs shrank, some crevices appeared. In addition, less fly ash formed on the top of specimens, and more bottom ashes remained in the original framework, with a clear network of structure built by the fibers. Carbon was almost absent in the fly ash; however, the weight ratio of C in the bottom ashes reached the maximum (> 43%) of the composition. Oxygen, Al, and Si appeared to have varying weight ratios for different ashes. Oxygen content increased with increasing Si and Al contents. Furthermore, Cl sharply decreased to less than 1% after combustion. Therefore, upon combustion, it was found that almost all of the substances in ULDFs, except for the Si-Al compound, were pyrolyzed to volatile carbon oxides and Cl compounds, especially the fly ash and lightweight C compounds.

12 1 - 50 of 65
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