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  • 51.
    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.
    Portable microNIR sensor for the evaluation of mould contamination on wooden surfaces2019In: Proceedings of the 62nd International Convention of ociety of Wood Science and Technology. Convention  Tenaya Lodge, Yosemite, California, USA, October 20-25: Theme: Renewable Materials and the Wood-based Bioeconomy, / [ed] LeVan-Green, S., SWST, Society of Wood Science and Technology , 2019, p. 46-51Conference paper (Refereed)
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  • 52.
    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.

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  • 53.
    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).

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  • 54.
    Neyses, Benedikt
    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.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The effect of ionic liquid and superbase pre-treatment on the spring-back, set-recovery and Brinell hardness of surface-densified Scots pine2020In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 74, no 3, p. 303-312Article in journal (Refereed)
    Abstract [en]

    Compressing the surface of sawn timber results in a substantial increase in hardness, and this opens up new market opportunities of using low-density timber species as the raw material for high-value wood products. Unfortunately, widespread commercialisation is hindered by the lack of an industrially viable surface densification process, the major obstacle being the set-recovery (SR) of the densified wood cells upon exposure to moisture. Our hypothesis is that partial dissolution of the crystalline cellulose during densification will largely prevent the SR of densified wood. We therefore evaluated the effect of ionic liquid (IL) or organic superbase pre-treatment on the elastic spring-back (SB), SR and Brinell hardness (HB) of surface-densified wood. Specimens of Scots pine were treated with solutions of ILs or superbases, and then densified in a hot press at temperatures between 200°C and 270°C. The SR was reduced from 90% for the control group to only about 10% for the treated materials. The treated and densified specimens exhibited a higher HB than their untreated and densified counterparts. The method presented in this study is a precursor to the development of a continuous densification process adapted for an open system. Further studies are needed to understand the underlying mechanisms of the pre-treatment.

  • 55.
    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.

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  • 56.
    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.

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  • 57.
    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.

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  • 58.
    Nordstierna, Lars
    et al.
    Industrial NMR Centre and Division of Physical Chemistry, Department of Chemistry, Royal Institute of Technology, Stockholm.
    Lande, Stig
    Kebony ASA, Porsgrunn.
    Westin, Mats
    SP Technical Research Institute of Sweden, Borås.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Furó, István
    Industrial NMR Centre and Division of Physical Chemistry, Department of Chemistry, Royal Institute of Technology, Stockholm.
    Towards novel wood-based materials: chemical bonds between lignin-like model molecules and poly(furfuryl alcohol) studied by NMR2008In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 62, no 6, p. 709-713Article in journal (Refereed)
    Abstract [en]

    Wood modification with furfuryl alcohol is a non-toxic alternative to conventional preservation treatments. A process in which furfuryl alcohol polymerises in situ was previously proposed for chemical modification of wood. In the present work, liquid model systems were investigated using compounds that resemble repeating units of lignin to verify whether chemical bonds form between the furfuryl alcohol polymer and wood. Using different NMR spectroscopic techniques we confirmed that these model compounds do form covalent bonds with the polymerising polymer. The results indicate that the furan polymer grafts to lignin, supporting observations in similar studies performed with genuine wood materials.

  • 59. Pantze, Anna
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    A model system to study esterification reactions in cellulosic or lignocellulosic material2007In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 33, no 4, p. 177-183Article in journal (Refereed)
    Abstract [en]

    The formation of natural ester cross-linkages in cellulosic or lignocellulosic composite materials during drying and heating is of interest for the production of paper and of wood composite boards and in giving cotton materials improved characteristics. A model system has been developed to study quantitatively the esterification of cellulosic material during drying and heating when solid-state conditions can be said to predominate. In the experiments, hexanoic acid and 3-hydroxybutyric acid were added to ordinary filter paper. Moisture content was adjusted, and samples were heated to temperatures ranging from 85 degrees C to 180 degrees C for between 15 and 45 minutes. Quantitative analysis of ester,formation, in this case between the monocarboxylic acids and the cellulose's hydroxyl groups, was performed using aminolysis/gas chromatography. The 3-hydroxybutyric acid was surprising v effective in ester formation. The results indicate that direct esterification of monocarboxylic acid can be an important reaction in lignocellulosic material at elevated temperatures.

  • 60. Pantze, Anna
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Esterification of carboxylic acids on cellulosic material: solid state reactions2008In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 62, no 2, p. 136-141Article in journal (Refereed)
    Abstract [en]

    In the present work, the formation of ester linkages in cellulosic materials during drying and heating was addressed. The results indicated that direct ester formation, without anhydride intermediate, occurs between carboxylic acids of suitable structure and cellulosic hydroxyls at 180 degrees C, even after reaction times as short as 5 min. The 2(R)-hydroxybutyric acid is most effective in ester formation, followed by 2-ketobutyric acid and 3-hydroxybutyric acid. Hexanoic acid is less effective and veratric acid produces no esters at all. At lower temperatures, 2-ketobutyric acid is the most reactive compound. One conclusion is that a hydroxyl or keto group in alpha position of the carboxylic acids favours ester formation. Another finding is that three pyrrolidine structures are produced after esterification and aminolysis of 2-ketobutyric acid. One of the structures indicates that 2-ketobutyric acid is reactive in two positions and could therefore be a potential cross-linker. A critical parameter for ester formation is pH, and the results indicate that pH < 2 strongly favours esterification, whereas almost no esters are produced at pH > 5-6. All experiments were performed in a solid-state model system (on cellulosic filter paper) with low moisture content. Esterification of five carboxylic acids was studied. Samples were heated constantly at 180 degrees C for 5 min or gradually from 22 degrees C to 180 degrees C over periods ranging from 5 to 45 min. Quantitative analysis of ester formation between the monocarboxylic acids and the hydroxyl groups of cellulose was performed by means of aminolysis and gas chromatography.

  • 61. Pantze, Anna
    et al.
    Westermark, Ulla
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Formation of ester cross linkage in lignocellulosic materials during drying and heating2005Conference paper (Other academic)
  • 62.
    Raudoniene, Jolanta
    et al.
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Skaudzius, Ramunas
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Zarkov, Aleksej
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Selskis, Algirdas
    Center for Physical Sciences and Technology, Vilnius, Lithuania.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kareiva, Aivaras
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Garskaite, Edita
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wet-chemistry synthesis of shape-controlled Ag3PO4 crystals and their 3D surface reconstruction from SEM imagery2019In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 345, p. 26-34Article in journal (Refereed)
    Abstract [en]

    A simple chemical solution-based synthesis route has been developed to prepare uniform and shape-controllable Ag3PO4 crystals. Tetrapod- and cube-shaped crystals having a size of about 9–10 μm were prepared from AgNO3 and NH4H2PO4 precursors, and pseudo-octahedral (equiaxial) crystals were prepared from AgNO3 and (NH4)2HPO4. TEM analysis revealed Ag3PO4 crystals to be electron beam sensitive materials, which under a voltage of 200 kV decompose to the metallic Ag, thereby demonstrating the difficulty in determining crystal facets and structural defects using conventional electron diffraction studies. UV–Vis diffuse reflectance spectroscopy was used to study the correlation between structural and optical properties of surfaces of Ag3PO4 crystals. Furthermore, a spatial 3-dimentional (3D) reconstruction of Ag3PO4 surface structures was performed from SEM images. The reconstruction produced realistic 3D mesh models, insomuch that the 3D reconstructed structures provided extra information about the examined crystals. Results suggested that the proposed synthesis route and performed spatial reconstruction of Ag3PO4 had the potential for simulating processing conditions to produce various microcrystals and explore material surface structures and reconstruction of microstructures.

  • 63.
    Sehlstedt-Persson, Margot
    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.
    Natural durability and phenolic content in dried Scots Pine heartwood2010In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 5, no 2, p. 1126-1142Article in journal (Refereed)
    Abstract [en]

    The durability of Scots pine heartwood has previously been shown to be affected by the industrial drying process of sawn lumber. The durability of heartwood from boards dried at temperatures between 20°C-110°C was studied by measuring the mass loss in a decay test with a brown rot fungus (Coniophora puteana), and the concentration of total phenolics was measured according to the Folin-Ciocalteu (FC) assay. The relation between mass loss and phenolics in dried heartwood showed a weaker negative correlation at lower levels of phenolics as compared to the strong relationship found in a study on heartwood from standing Scots pine trees. Mass loss in dried heartwood showed a weak negative correlation to density. Heating of extractives-rich green sawdust under moist conditions resulted in a reduction of phenolics with temperature up to 180 oC and with increasing time. The concentration of phenolics in heated, green sawdust was higher in extractives-rich pine heartwood than in heartwood with a normal extractives content.

  • 64.
    Sehlstedt-Persson, Margot
    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.
    Wamming, Thomas
    SP Träteknik.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Mold growth on sapwood boards exposed outdoors: the impact of wood drying2011In: Forest products journal, ISSN 0015-7473, Vol. 61, no 2, p. 170-179Article in journal (Refereed)
    Abstract [en]

    Mold growth on dried Norway spruce and Scots pine sapwood boards was investigated in an accelerated outdoor field test for 96 days. The boards were dried using three different methods of stacking: single stacking, double stacking with the sapwood sides in each pair facing toward each other, and double stacking with sapwood sides facing outward. Drying was performed at three temperatures: 25ºC, corresponding to air drying, and kiln drying at 70ºC and 110ºC. The degree of mold growth was visually assessed on both sides of each board. On average, pine boards showed a higher level of mold growth than the spruce boards. The highest average level of mold growth was found on the boards kiln dried at 708C, whereas the air-dried boards and the boards kiln dried at 110ºC showed considerably less mold growth. Stacking the boards during drying had a large impact on mold susceptibility of the sapwood. This study confirmed that, during the drying process, it is possible to direct the migration of nutrients in sapwood toward one chosen side of each board by double stacking; the opposite side leaches out, which has a great impact on surface mold growth. Chemical analyses of monosaccharide sugar gradients beneath the boards’ surfaces confirmed the results.

  • 65.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Persson, Fredrik
    SP Trätek.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ahmed, Sheikh Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Virkestorkningens inverkan på impregnerbarhet i furusplint – Del II: TCN Delrapport 12013Report (Other academic)
    Abstract [sv]

    Projektets målsättning är att undersöka om och hur virkestorkning påverkar impregnerbarhet i furusplint med vattenbaserat kopparmedel, samt att ge rekommendationer om hur torkningsbetingelserna kan göras så gynnsamma som möjligt för ett bra impregneringsresultat. Det bör tydliggöras att det virke som impregnerats i denna studie inte kommer att säljas inom detaljhandeln. Virket anses inte heller vara representativt för impregnerat virke då det har impregnerats vid fuktkvoter som avsiktligt avviker från normala förhållanden och som kan antas vara ogynnsamma för inträngningen. Virket impregnerades enligt Nordiska Träskyddsföreningen (NTR) klass AB.I delsteg 1 som avrapporteras i denna rapport, har huvudfrågan varit att undersöka inverkan av fuktkvotsnivå och maxtemperatur under torkningen på impregneringsresultatet. Försöksmaterialet har bestått av totalt 553 hyvlade bräder och plank (28 resp. 48 mm). Både planken och bräderna sågades fram ur centrumutbyte och innehöll därför kärnved. Virket torkades industriellt vid 60°C och 80°C maxtemperatur till tre målfuktkvoter: 24 %, 18 % och 10 %. Efter impregnering har samtliga virkesstycken kapats upp var 50:e cm och impregneringsresultat har analyserats visuellt enligt NTR:s bedömningsgrunder. Vissa kemiska analyser har även utförts för att undersöka om och hur extraktiver och fetter kan förklara impregneringsmissarna i bräderna. Undersökningen visar att virkesdimension, fuktkvot och temperaturnivå har betydelse för impregneringsresultatet. Totalt sett fanns det fler missar i planken än i bräderna. Plank och bräder uppvisar dessutom något olika beteende: för bräder är resultatet mera tydligt vilket även framkom vid multivariat dataanalys (MVDA) på medelvärdesnivå: högre temperatur och högre fuktkvot visar minst impregneringsmissar hos brädgrupperna. För plankgrupper erhölls överhuvudtaget inga MVDA-modeller. Även för plank hade den högre temperaturen i medel bättre impregneringsresultat. Sambandet hög fuktkvot och god impregnerbarhet är inte lika tydligt för plank, möjligen att kombinationen låg temperatur och låg fuktkvot är ogynnsam.Densitetsvariationerna visade sig vara tämligen liten och inga låga/höga extremvärden fanns i försöksmaterialet. Vid MVDA framkom ändå tendenser att det hos bräder var gynnsamt ur impregneringssynpunkt med högre densitet.Kemiska analyser visar inga dramatiska omfördelningar av extraktiver under torkning som förklaring till impregneringsmissar. Detekterbara fetter och hartssyror var dock lägre i ytliga än i inre delar av splintveden troligen beroende på oxidativ förnätning av deras struktur under torkningen.Sammanfattningsvis blir tolkningen att torktemperatur, fuktkvotsintervall och virkesdimensioner har betydelse för impregneringsresultat men att det finns ett antal okända materialvariabler som har stor inverkan på resultatet på individnivå. Även om torkningsbetingelserna görs så gynnsamma som möjligt för impregnering förekommer individer som har allvarliga genomgående missar.

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  • 66.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wamming, Thomas
    SP Trätek.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Processanpassning för funktionsbeständiga träprodukter: Vilken roll spelar torkningen för mögelpåväxt på brädor i utomhusprodukter ovan mark?2010Report (Other academic)
    Abstract [sv]

    Torkningsprocessens inverkan på mögelbenägenhet hos råspont i utomhusanvändning har studerats. Brädor postat som sidoutbyte från vinterfällt virke har använts i försöken. De torkningar som utvärderats är friluftstorkning, artificiell torkning vid 70°C samt en HT (högtemperatur) torkning vid 110°C. Som utvärderingsmetod har ett forcerat mögeltest utomhus använts. Mögelpåväxten har därefter bedömts visuellt på provbrädornas båda sidor.I projektansökan ingick enbart undersökning av träslaget gran men i försöken har även furu ingått. Anledningen till denna utökning av projektet med träslaget furu är att projektutförarna ville vara säkra på att effekter av olika variabler skulle bli tydliga nog för utvärdering av torkningens inverkan, då furu på grund av sin högre näringshalt i splintveden förväntas vara mer mögelbenäget än gran. Projektets arbetshypoteser har varit följande:•en anrikning av näringsämnen sker i gransplint under torkning•näringsanrikning mot ytan kan styras under torkning•den av torkningen påverkade näringsanrikningen i splintved mot ytan har betydelse för virkesytans mögelbenägenhet •den näringsanrikade zonen kan påverkas termiskt genom värmning och göras mindre ”aptitlig” för mögelsvampar I projektets inledande del undersöktes om en näringsgradient finns i den torkade virkesytan även i gransplint på samma sätt som det väl dokumenterat finns i furu. Denna anrikning av kolhydrater påverkas i hög grad av hur snabbt, ”hårt” torkningen görs i den inledande kapillära torkningsfasen. Den inledande kemiska kolhydratanalys av torkad gransplint som gjordes bekräftade att en anrikning av kolhydrater sker även i gransplint under torkning. På det artificiellt torkade provmaterialet har ur varje prov gjorts ett avkap efter torkning. På dessa avkap har effekten på mögelbenägenhet av två olika efterbehandlingar genom värmning i tork undersökts: 3 timmars torr värmning upp till 90°C samt 3 timmars värmning med mättad vattenånga upp till 90°C.En intressant idé dök upp under projektets inledande planering med ursprung i iakttagelsen att synlig mögelpåväxt inte tycks finnas på ytor där strön legat an mot virket och blockerat fuktavgången. Idén bygger på hypotesen att näringsanrikning i splintved under torkning är möjlig att styra mot en av brädornas flatsidor genom dubbelläggning av brädor under torkning. Vid efterföljande hyvling av brädor till råspont väljs den näringsurlakade flatsidan som utsida och den näringsanrikade sidan och kanterna bearbetas. Inledande försök på små prover av furusplint bekräftade hypotesen att näringsanrikning kan styras mot en sida av brädan. Därför togs i projektet beslutet att undersöka effekterna på mögelbenägenhet av olika kombinationer av dubbelläggning av virke under torkning. Eftersom idén vid utvärdering visade mycket lovande resultat har under projektets gång en patentansökan av metoden, att genom dubbelläggning av virke under torkning styra näringsvandringen i splintved mot vald yta och på så sätt åstadkomma virkesytor med minskad mögelbenägenhet inlämnats till PRV den 2010 02 17.Resultaten sammanfattas under följande rubrikerAnrikning av näringsämnen i gransplintI projektet konstateras att •kemisk kolhydratanalys av torkad gransplint bekräftar att en näringsanrikning sker även i gransplint under torkning•denna anrikade ”front” även kan bekräftas visuelltStyrning av näringsanrikning mot ytan under torkningI projektet konstateras att •näringsanrikning i splintved kan styras mot en flatsida under torkning genom dubbelläggning•mest näring i ytan finns i splintsidor som lagts utåt i dubbelläggning•minst näring i ytan finns i märgsidor som lagts mot varandra under torkningMögelbenägenhet hos torkade splintvedsytorI projektet konstateras att •den under torkning anrikade näringen mot splintvedsytor har stor betydelse för virkesytans mögelbenägenhet •furusplint är mer mögelbenäget än gransplint•HT-torkning vid 110°C visar låg mögelgrad i gran vid både enkel- och dubbelläggning •friluftstorkad gran visar låg mögelgrad vid enkelläggning•forcerad torkning vid 70°C uppvisar mest mögelpåväxt i både gran och furu•genom dubbelläggning av gran med ”rätt” flatsidor mot varandra kan ytor med låg mögelpåväxt åstadkommas även vid 70°C•det forcerade mögeltestet utomhus som använts som utvärderingsmetod har fungerat utmärkt Efterbehandling i tork genom torrvärmning och ångvärmningI projektet konstateras att •för gran torkat vid 70°C ger både ånga och torrvärmning signifikant lägre mögelpåväxt jämfört med ej efterbehandlat•i furu ger dessa efterbehandlingar inte signifikant lägre mögelpåväxt Inverkan på mögelbenägenhet av vankant och maskinskador i virket I projektet konstateras att •förekomst av vankant och maskinskador i virket ökar mögelbenägenheten på splintsidan•även brädor med mycket vankant/maskinskador som dubbelläggs kan ha låg mögelbenägenhet på motlagda flatsidor

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  • 67.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wamming, Thomas
    SP Trätek.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ahmed, Sheikh Ali
    Modern torknings inverkan på impregnerbarhet i furusplint: Förstudie2011Report (Other academic)
    Abstract [sv]

    Under senare år rapporteras i Sverige för vissa impregneringsmedel en kraftig ökning av antalet underkända prov och då speciellt för kopparbaserade vattenlösliga medel. På några års sikt, när konsekvenserna av impregneringsmissar blir synliga hos slutanvändaren genom att rötskadat virke måste bytas ut, beräknas kostnaderna kunna uppgå till en halv miljard årligen. Orsakerna till inträngningsproblem diskuteras och en av många teorier är att virkestorkningen är en av huvudorsakerna. Målet med denna förstudie har varit att identifiera relevanta process- och materialvariabler som misstänks inverka på impregnerbarheten i furusplint. Resultat från impregneringsförsöken i denna förstudie visar att fuktkvotsnivån i bräder efter torkning är viktig för impregneringsresultatet. Bäst inträngning erhölls vid högre fuktkvotsnivåer än vad som vanligen används vid anläggningarna idag: i fuktkvotsintervallet 20-25 % var andelen missar lägst medan andelen missar ökade påtagligt vid sjunkande fuktkvot. En rekommendation är att inte övertorka virke som ska impregneras. Detta är vanligt speciellt vid torkning av tunna dimensioner i äldre brädkanaler.Resultat från denna förstudie sammanfattas enligt följande•Inverkan av fuktkvotsnivå vid impregnering är viktig. Bäst inträngning i bräder erhölls i fuktkvotsintervallet 20-25 %, dvs. vid högre fuktkvot än vad som vanligen görs medan missarna ökade påtagligt vid sjunkande fuktkvot. •Resultaten pekar på att splintvedsdensiteten tycks spela roll för impregnerbarheten: högre densitet tenderar att vara bättre ur impregneringssynpunkt. •Olika typer av impregneringsmissar noteras. Vissa typer har en tydlig koppling till vedanatomiska detaljer medan andra missar kopplas till process och yttre form.•Anrikning av näring mot splintvedsytor som sker vid forcerad torkning kan i vissa fall ha försvårat inträngning av träskyddsmedel.•Vedanatomiska studier visar att– axiella kådkanaler sannolikt spelar en viktig roll för inträngning av träskyddsmedel– parenkymcellers hartsinnehåll i splintved kan blockera inträngning via märgstrålar•Tomografering indikerar att hög splintvedsdensitet är gynnsamt för inträngning av träskyddsmedel. Detta överensstämmer med iakttagelsen att axiella hartskanaler är viktiga för inträngning av träskyddsmedel eftersom axiella hartskanaler främst finns i sommarved och hög densitet förknippas med hög sommarvedsandel. •Kemisk analys indikerar att lokal skillnad i extraktivämneshalt kan vara en av förklaringarna till impregneringsmiss i splintved. •I fortsatta studier är tomografering ett kraftfullt analysverktyg för att se inträngningsmissar i rått tillstånd.

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  • 68.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wamming, Thomas
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Skog, Johan
    Processanpassning för funktionsbeständiga träprodukter: vilken roll spelar torkningen för virkets beständighet i utomhusprodukter ovan mark?2008Report (Other academic)
    Abstract [sv]

    Torkningsprocessens inverkan på beständigheten hos centrumsågat furuvirke 50x125 mm har studerats. Som utvärderingsmetod har röttester med brunrötesvampen Coniophora puteana (källarsvamp) gjorts på prov från splintved samt inre och yttre kärnved. Stor massförlust efter röttest visar på dålig beständighet. De torkningar som utvärderats är lufttorkning, artificiell torkning vid 70°C och 90°C samt en högtemperaturtorkning vid 110°C. För 70°C och 90°C torkningarna har två principscheman använts: ett med snabb temperaturökning i virket tidigt i torkningen och ett där virkestemperaturen når maxtemp i ett betydligt senare skede. Även inverkan av ångkonditionering i slutet av torkningen har utvärderats. Skanning med UV-ljus har utförts på virkestvärsnitt från samtliga torkningar för att undersöka hur UV-fluorescens av pinosylvin i kärnved påverkas av torkning samt om denna skanningsmetod kan användas för att prediktera massförlust (beständighet). Kapillärupptag av vatten i splint från de olika torkningarna har studerats i tomograf. Totalhalten av fenoliska ämnen i torkad kärnved, som av andra forskare visats ha stor betydelse för rötbeständighet mot källarsvamp på färsk ved, har bestämts med Folin-Ciocalteu (FC) metoden. Inledningsvis gjordes två serier med homogent spån (från virke som ej ingår i torkförsöken) som värmdes vid olika temperaturer. När resultaten från röttesterna från det torkade försöksvirket var kända utvaldes provplankor med lägst och högst massförlust ut från samtliga torkningsserier och analyserades med avseende på extraktivämneshalt och totalfenolhalt enligt FC-metoden. Resultaten sammanfattas under följande rubriker Råvaran Vid röttest med källarsvamp på torkat furuvirke konstateras Splintved ha betydligt sämre rötbeständighet än kärnved. Ingen skillnad i rötbeständighet mellan inre och yttre kärnved. Stor spridning i rötbeständighet mellan olika plankindivider men även inom en och samma planka i längdled. Svag indikation att högre veddensitet har bättre beständighet. Trolig förklaring är extraktivämneshalt. Totalfenolhalten vara högre i kärnved med hög extraktivämneshalt jämfört med låg extraktivämneshalt. Totalfenolhalten i spån från fet kärnved minskar vid värmning över 40°C upp till 110°C. Högre totalfenolhalt indikera lägre massförlust även i torkad furukärna. Torkning Vid beständighetstest med källarsvamp på furuvirke torkat vid olika temperaturer konstateras Splintved ha betydligt större massförlust än kärnved i samtliga torkningar Kärnved från lufttorkat virke ha minst massförlust vid röttest. Splintved och kärnved från virke torkat vid 90°C med snabb temperaturökning i virket ha störst massförlust vid röttest. Ångkonditionering efter torkning öka massförlusten vid röttest i furusplint. UV-skanning Vid UV-skanning av virkestvärsnitt från samtliga torkningar konstateras att färgkomponenter kan separera: - Virke torkat vid 20°C och 70°C från virke torkat vid 90°C och 110°C. - Inre kärnved från yttre kärnved och splintved. att signalerna måste kalibreras då möjligen även inslag av "vanlig färg" iveden ingår i signalerna. Kapillärförsök Då ingen fullständig utvärdering av tidsskäl hunnit göras konstateras här endast att Skillnader mellan olika torkningar kan ses i fuktgradienternas utseende i axiell led efter 6 dygns uppsugning. En tänkbar förklaring kan vara övergångar mellan olika mekanismer för vattenupptagning som har att göra med torkningssätt och temperatur, exempelvis söndertrasade pormembran i det artificiellt torkade virket eller förändrade vätningsegenskaper i veden vid högre temperatur. Projektets målsättning att formulera rekommendationer för beständighetsanpassad torkning av furuvirke sammanfattas enligt följande: Den kritiska parametern under torkningsprocessen för beständigheten i kärnved är virkestemperaturen tidigt i torkningen. För artificiell torkning i virkestork bör därför torkstyrningen anpassas så att virkestemperaturen hålls nere tidigt i torkningen när fuktkvoten är hög. För rötbeständighet i splintved är ångkonditionering efter torkning mindre lämplig.

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  • 69.
    Sekan, Alona S.
    et al.
    Institute of Food Biotechnology and Genomics, National Academy of Science of Ukraine, Kyiv, Ukraine.
    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.
    Gryganskyi, Andrii P.
    LF Lambert Spawn Co., Coatesville, PA, USA.
    Blume, Yaroslav
    Institute of Food Biotechnology and Genomics, National Academy of Science of Ukraine, Kyiv, Ukraine.
    Green potential of Pleurotus spp. in biotechnology2019In: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 7, article id e6664Article in journal (Refereed)
    Abstract [en]

    Background

    The genus Pleurotus is most exploitable xylotrophic fungi, with valuable biotechnological, medical, and nutritional properties. The relevant features of the representatives of this genus to provide attractive low-cost industrial tools have been reported in numerous studies to resolve the pressure of ecological issues. Additionally, a number of Pleurotus species are highly adaptive, do not require any special conditions for growth, and possess specific resistance to contaminating diseases and pests. The unique properties of Pleurotus species widely used in many environmental technologies, such as organic solid waste recycling, chemical pollutant degradation, and bioethanol production.

    Methodology

    The literature study encompasses peer-reviewed journals identified by systematic searches of electronic databases such as Google Scholar, NCBI, Springer, ResearchGate, ScienceDirect, and ISI Web of Knowledge. The search scheme was divided into several steps, as described below.

    Results

    In this review, we describe studies examining the biotechnological feasibility of Pleurotus spp. to elucidate the importance of this genus for use in green technology. Here, we review areas of application of the genus Pleurotus as a prospective biotechnological tool.

    Conclusion

    The incomplete description of some fungal biochemical pathways emphasises the future research goals for this fungal culture.

  • 70. Sundqvist, Bror
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Westermark, Ulla
    Determination of formic-acid and acetic acid concentrations formed during hydrothermal treatment of birch wood and its relation to colour, strength and hardness2006In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 40, no 7, p. 549-561Article in journal (Refereed)
    Abstract [en]

    Formation of benzyl esters from acetic and formic acids during heat treatment of birch at 160-200°C has been studied by gas chromatography. High concentrations of formic and acetic acids formed by the wood itself during hydrothermal treatment were found. The concentrations of acids increased with both treatment time and temperature. The maximum formic- and acetic acid concentrations found at 180°C and after 4 h of treatment performed in this work were 1.1 and 7.2%, based on dry-weight wood, respectively. The treated wood material was characterised by mechanical testing [bending tests perpendicular to the grain, modulus of rupture, modulus of elasticity, Brinell hardness, impact bending and colour measurements (CIE colour space)]. The experiments, where high concentration of acids was formed, showed severe losses in mass and mechanical strength. Indications of possible enhanced mechanical properties for the treated, compared with untreated birch wood were found around 180-200°C at short treatment times. This paper discusses possible degradation reactions coupled with the colour and mechanical properties in relation to acid formation, and suggestions for process optimisations.

  • 71. Yang, Qian
    et al.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ahmed, Sheikh Ali
    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.
    Dimensional stability and water repellency of european aspen improved by oxidized carbohydrates2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 1, p. 487-498Article in journal (Refereed)
    Abstract [en]

    Small samples from European aspen (Populus tremula L.) were impregnated with carbohydrates oxidized by Fenton’s reagent using water in a vacuum, followed by heating in an oven at 103°C. An antiswelling efficiency (ASE) of around 45% for wood treated with oxidized glucose and 35% for wood treated with oxidized sucrose was obtained. Samples treated with oxidized carbohydrates gave water repellent effectiveness (WRE) values over 35%. The decrease in cell wall thickness during impregnation was about 18% less in the presence of oxidized glucose than samples only treated with Fenton’s reagent. An ASE of 20% for the wood samples that had been treated with oxidized glucose was obtained after 7 days of soaking in water. The reasons for the improvement in dimensional stability are discussed in this work.

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  • 72.
    Yoon, Kukjin
    et al.
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Takahashi, Shiho
    Forestry and Forest Products Research Institute, Tsukuba, Ibaraki.
    Nge, Thi Thi
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Forestry and Forest Products Laboratory, Tsukuba, Ibaraki.
    Nakagawa-izumi, Akiko
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Ohi, Hiroshi
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Uraki, Yasumitsu
    Faculty of Agriculture, Hokkaido University, Sapporo.
    Yamada, Tatsuhiko
    Graduate School of Life and Environmental Sciences, University of Tsukuba, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki.
    Thermal Melting of Lignin Derivates Prepared from Dried Black Liquor Powder of Softwood Soda-AQ Cooking and Polyehylene Glycol2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 1, p. 912-921Article in journal (Refereed)
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