| 1. |
- Skovsgaard, Jens Peter
(författare)
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Bog om tarmvridrøn
- 2013
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Ingår i: Skoven. - 0106-8539. ; 45, s. 551-551
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Book review N. Mayer & R.T. Klumpp (ed.) 2013: Elsbeere in Österreich – Monographie. Verein zur Erhaltung, Pflege und Vermarktung der Elsbeere - Genussregion Wiesenwienerwald Elsbeere, Michelbach.
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| 2. |
- Fernando, Dinesh, et al.
(författare)
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Characterization and biological depectinization of hemp fibers originating from different stem sections
- 2015
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Ingår i: Industrial Crops and Products. - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 76, s. 880-891
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Tidskriftsartikel (refereegranskat)abstract
- The wide variation of mechanical properties of natural fibers limits their applications in matrix compos-ites. The aim of this study is to evaluate the properties of hemp fibers from different stem sections (top,middle and bottom) and to assess fungal retting pretreatment of hemp from different stem sections withthe white rot fungi Phlebia radiata Cel 26 and Ceriporiopsis subvermispora. For the untreated hemp fibers,no apparent difference in tensile behavior for fiber bundles from different stem sections was observed,and more than 90% tested samples demonstrated plastic flow behavior. Fiber strength and stiffness werehighest for the fibers from the top and middle stem sections. These properties were related to the compositional make up and morphological properties of hemp fibers, notably the secondary fiber cell contents.In fungal retting, there was a strong dependence of depectinization selectivity on stem section, whichdecreased from bottom to top presumably due to the significantly higher lignin content in the bottomsection than in the top section (middle section was in between). Consequently, the fungal retting caused alower reduction in strength of fibers from the bottom section than in those from the top stem section, andessentially reversed the influence of stem section on fiber tensile strength through depectinization selec-tivity. At whole hemp stem level, the fungal retting with P. radiata Cel 26 exhibited better mechanicalproperties with an ultimate tensile strength, strain and stiffness of 736 MPa, 2.3% and 42 GPa, respec-tively, while fibers treated with C. subvermispora exhibited lower mechanical properties of 573 MPa, 1.9% and 40 GPa, respectively. The study thus also showed that less variable and high strength fibers may beproduced using the dependence of depectinization selectivity on stem section for composite application
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| 3. |
- Fernando, Dinesh, et al.
(författare)
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Effect of harvest time and field retting duration on the chemical composition, morphology and mechanical properties of hemp fibers
- 2015
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Ingår i: Industrial Crops and Products. - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 69, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- The large variability in the mechanical properties of hemp fibers creates difficulties for using them in high-grade composites. The objective of the present study was to determine the optimal growth stage for harvesting hemp fibers for use in composites and to evaluate the effect of field retting time on mechanical performance of the fibers. Reduction in bast content and thickness of the primary bast fiber layer in stems were found to be highly significant (P ˂ 0.01) with plant maturity. A significant increase in the secondary fiber fraction occurred with maturity, reaching a maximum value of 10% at seed maturity. A highly significant reduction in cellulose deposition in fiber cell walls was reflected by reduced fiber wall thickness with plant maturity and was related to the development and ripening of hemp seeds. A statistically significant increase in lignin deposition and slight decrease in pectins in hemp fiber cell walls was also noted with stem maturity. Microscopy observations and histochemical analyses corroborated results from chemical analyses and showed variations in morphological aspects and spatial micro-distributions of carbohydrates and lignin within the cell structure of the hemp stems between early- and late growth phases. Fibers harvested at the beginning of flowering exhibited high tensile strength and strain, which decreased with plant maturity. Reduction in strength was related to the increase in proportion of secondary fibers and decrease in cellulose deposition leading to inferior properties of the primary fibers. A negative effect of field retting occurred only after long term field retting (i.e. 70 days) which was presumably due to accelerated degradation of cellulose by the action of microorganisms.
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| 4. |
- Hallingbäck, Henrik, et al.
(författare)
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Association mapping in Salix viminalis L. (Salicaceae) - identification of candidate genes associated with growth and phenology
- 2016
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Ingår i: Global Change Biology Bioenergy. - : Wiley. - 1757-1693 .- 1757-1707. ; 8:3, s. 670-685
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Tidskriftsartikel (refereegranskat)abstract
- Willow species (Salix) are important as short-rotation biomass crops for bioenergy, which creates a demand for faster genetic improvement and breeding through deployment of molecular marker-assisted selection (MAS). To find markers associated with important adaptive traits, such as growth and phenology, for use in MAS, we genetically dissected the trait variation of a Salix viminalis (L.) population of 323 accessions. The accessions were sampled throughout northern Europe and were established at two field sites in Pustnas, Sweden, and at Woburn, UK, offering the opportunity to assess the impact of genotype-by-environment interactions (GxE) on trait-marker associations. Field measurements were recorded for growth and phenology traits. The accessions were genotyped using 1536 SNP markers developed from phenology candidate genes and from genes previously observed to be differentially expressed in contrasting environments. Association mapping between 1233 of these SNPs and the measured traits was performed taking into account population structure and threshold selection bias. At a false discovery rate (FDR) of 0.2, 29 SNPs were associated with bud burst, leaf senescence, number of shoots or shoot diameter. The percentage of accession variation explained by these associations ranged from 0.3% to 4.4%, suggesting that the studied traits are controlled by many loci of limited individual impact. Despite this, a SNP in the EARLY FLOWERING 3 gene was repeatedly associated (FDR<0.2) with bud burst. The rare homozygous genotype exhibited 0.4-1.0 lower bud burst scores than the other genotype classes on a five-grade scale. Consequently, this marker could be promising for use in MAS and the gene deserves further study. Otherwise, associations were less consistent across sites, likely due to their small estimates and to considerable GxE interactions indicated by multivariate association analyses and modest trait accession correlations across sites (0.32-0.61).
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| 5. |
- Edvardsson, Johannes, et al.
(författare)
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Old wood in a new light : an online dendrochronological database
- 2023
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Ingår i: International Journal of Wood Culture. - : Brill Academic Publishers. - 2772-3194 .- 2772-3186. ; 3:1-3, s. 442-463
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Tidskriftsartikel (refereegranskat)abstract
- The Old Wood in a New Light database project focuses on the digitization and accessibility of the results of dendrochronological samples analyzed and archived at four Swedish university-based tree-ring laboratories at Lund University, Stockholm University, University of Gothenburg, and the Swedish University of Agricultural Sciences. Collaboration with the Environmental Archaeology Laboratory and Humlab at Umeå University enables long-term open access to data, raw data, and metadata. In this project, we (1) systematically undertake large-scale entry and open access publication of results from wood samples scientifically analyzed and archived by Swedish laboratories and the associated metadata, into the Strategic Environmental Archaeology Database (SEAD; www.sead.se) research data infrastructure, and (2) actively promote the database as a resource for new and ongoing interdisciplinary research initiatives. Including dendrochronological data in SEAD infrastructure allows interdisciplinary studies that combine major scientific and societal questions. Building on a pilot study of construction timber from southern Sweden and adaptation of SEAD digitization workflows, more than 70 000 samples archived at the four dendrochronological laboratories are now being handled in the project. The broad coverage of research networks, stakeholder interaction, and strategic support from the cultural heritage community is guaranteed owing to the ongoing collaboration between laboratories and an established international and multidisciplinary reference group.
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| 6. |
- Jiang, Wen, et al.
(författare)
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Particleboards with partially liquefied bark of different sizes
- 2019
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Ingår i: 3rd International Scientific Conference “Wood-Science-Economy”, 21-22 October, Poznan, Poland. - Poznan : ACSmedia Pracownia Reklamy. ; , s. 30-30
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Konferensbidrag (refereegranskat)abstract
- Utilizing biomass waste for wood-based composites has been driven by harsh competition for raw materials and environmental concerns for more sustainable products. Bark, as a by-product of the sawmilling and pulping industries, is a lignocellulosic material that is rich in lignin and extractives, and holds potential for producing chemicals and value-added materials. There are many possibilities of using bark in wood-based panel manufacturing such as making adhesives (e.g. bark tannin extractives, liquefied bark) or using it as a furnish in small amounts. Instead of using the completed liquefied bark products in the adhesive mixture, we have been working on a novel method of making particleboards by using partially liquefied bark as a furnish material with binding abilities. Thus, partially liquefied bark was mixed with wood chips with an aim to investigate the effect of different bark sizes on the properties of particleboards.Maritime pine (Pinus pinaster Ait.) bark was partially liquefied in the presence of ethylene glycol as solvent and sulphuric acid (H2SO4) as catalyst in 180˚C for 30 minutes. Four different sizes of bark were used: mix, coarse (> 2 mm), middle (1-2 mm), and fines (< 1 mm). One-layered 8-mm particleboards were prepared by mixing dry wood chips with the partially liquefied bark categories (9.1% or 20% w/w). Melamine-urea-formaldehyde (MUF) resin was 10% of the total weight of the furnish materials (dry wood chips and partially liquefied bark); while boards were also made without adding the resin. Mechanical and physical properties of the particleboards were tested according to the European standards, and ANOVA analysis of the results showed no statistically significant differences between varying bark sizes. Particleboards made with 9.1% of partially liquefied bark and with 10% of MUF resin met all the standard requirements for mechanical strength and thickness swelling. Particleboards made with 20% of partially liquefied bark and without adding MUF resin were inferior to those with MUF resin.From the current results we can conclude that it is possible to make particleboards from partially liquefied bark with competitive properties, and this supports our original idea of not completing the liquefaction process. In that respect, our work can contribute to energy and material savings when using liquefied products in wood panel manufacturing. More research is needed to optimize the process as well as to evaluate the formaldehyde emission level from this type of panels.
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| 7. |
- Neyses, Benedikt, 1986-, et al.
(författare)
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Continuous densification of solid wood – The belt press approach
- 2022
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Ingår i: Proceedings of the 10th European Conference on Wood Modification. - Nancy : University of Lorraine, Faculty of Science and Technology, Laboratory of Study and Research on the Wood Material (LERMaB). ; , s. 76-79
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Konferensbidrag (refereegranskat)abstract
- The densification, i.e., transverse compression of solid wood can lead to improvements in the mechanical properties, and this can expand the areas of application for low-density wood species. For the past one hundred years, many efforts have been made to mass-produce densified wood products, but despite being available on the market, they remain niche products with low annual production volumes. One of the main reasons for this is that all available densified wood products are produced in a batch-type process, which limits the achievable process speed and integration into the continuous wood processing chain. For this reason, we propose a continuous surface densification process using a bespoke belt press – similar in principle to those used to produce MDF panels. The belt-press is capable of densifying full-sized wood boards at processing speeds of up to 60 m min-1. The primary belt for densification can be heated to temperatures above 160°C, while a subsequent belt functions as a cooling stage. During the densification process, the belt press can log the pressing forces, moments, and temperature. Preliminary tests with Scots pine specimens of 120 mm in width and 38 mm in thickness resulted in a twofold increase in peak density, after a pressing time of two minutes at 120°C. The resulting density profiles were similar to those obtained in studies using a static hot press. As the belt press can be fed with a continuous stream of boards, it has a higher net throughput than a static hot press. Further studies continue with the aim to evaluate different aspects relevant to the large-scale industrial production of densified wood products.
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| 8. |
- Norbakhsh, Shahin, et al.
(författare)
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Impact of iron(II) and oxygen on degradation of oak - modeling of the Vasa wood
- 2014
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 68:6, s. 649-655
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Tidskriftsartikel (refereegranskat)abstract
- In the wood of the Swedish 17th century warship Vasa, iron (Fe)-catalyzed chemical degradation has taken place after the salvation in 1961, which is manifested in increased acidity accompanied by cellulose degradation and reduced strength in the oak hull. Model studies on fresh oak impregnated with Fe(II) also led to tensile strength (TS) reduction in the same order of magnitude as observed in the wood of the Vasa. In the present study, further experiments have been performed concerning the Fe-catalyzed wood degradation. Namely, the degree of wood degradation was monitored quantitatively by measurement of the O-2 consumption of Fe(II)-impregnated oak, kept in closed vials with different relative humidities (RH), as a function of time. The initial O-2 consumption was high and declined with time. After 200 days, the accumulated O-2 consumption was 0.3-0.4 mmol g(-1) wood. Degradation products with low molecular weight were analyzed. The release of CO2 and oxalic acid (OA) was positively correlated with RH (0.235 and 0.044 mmol g(-1), respectively, at RH98% after 200 days). Samples kept for 1500 days at RH54% had accumulated 0.044 mmol OA g(-1) wood, which is equal to the average OA content in the interior of Vasa oak (corresponding to 4 mg g(-1)). Oak samples, from which extractives had been removed prior to Fe(II) impregnation, did not change their O-2 consumption or TS reduction compared to the nonextracted samples, indicating that extractives are not essential for cellulose degradation in this context.
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| 9. |
- Sandberg, Dick, 1967-
(författare)
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Simuleringsverktyg för skiktlimning – nulägesanalys av processen och prioriterade arbetsområden. : Simulation Tools for laminated bending of veneer - state of the art for the process and priority work.
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport är en dokumentation av villkor och förutsättningar som gäller vid skiktlimning av faner för inredning och möbler inom delprojektet ”Skiktlimning av björk och bok” vid AB Åberg & Söner i Lönsboda.En analys av skiktlimningsprocessens status ger vid handen:Stora kunskapsluckor finns om de grundläggande fenomenen vid skiktlimning.Tydlig förändring av processerna sker mot:- mer avancerade produkter- korta serier- korta leveranstider- fokusering på pris och kvalitetSkiktlimning är ett av de få områden där svensk trämanufakturindustri har möjlighet att konkurrera mot låglöneländer.Ett framtidsscenario är att om 5 till 10 år kommer i stort sett alla beställningar via arkitekter och designers till företaget på elektronisk väg. Ritningarna är gjorda med hjälp av något CAD program. På grund av kravet på korta ledtider och utvecklingen mot allt mer avancerade produkter måste man kunna öppna och läsa olika CAD-program och utifrån dessa ritningar kunna avgöra om det är möjligt att i sin tillverkning tillverka den önskade produkten. Till sin hjälp i denna situation är företaget i behov av ett simuleringsverktyg i form av en matematisk modell som man har tillgång till. Med hjälp av detta verktyg skall risken kunna beräknas för att lokala brott i faneren inträffar, sprickor och limsläpp uppstår, samt att andra orsaker vid produktionen förorsakar kassaktioner av den färdiga eller nära färdiga produkten. Ytterligare ett önskemål är att det ritningsunderlag som man i digital form får från arkitekter i dess ursprungsform kan ligga till grund för tillverkningen. En analys av dagens tillverkning i relation till de framtida behoven som företaget kommer har genomförts och redovisas med förslag.
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| 10. |
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| 11. |
- Ager, Bengt
(författare)
-
Fördjupade studier av det maskinella drivningsarbetets humankvalitet åren kring 2010 : efterskrift till Arbetsrapport 378/2012 vid SLU, inst. för skoglig resurshushållning ”Skogsarbetets rationalisering och humanisering 1900-2011 och framåt”
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna efterskrift till SLU Arbetsrapport 378/2012 ”Skogsarbetets rationalisering och humanisering 1900-2011 och framåt” sker en fördjupad granskning av de senaste årens förändring och nuläget i det maskinella drivningsarbetets humankvalitet. Granskningen bekräftar mina utsagor om de enskilda humankvaliteternas förändring som gäller dels försämringar i form av minskade personliga kontakter, ökad prestationspress, mindre variation i arbetet, mer raka tvåskift, längre arbetsresor, försämrad relativ lönenivå samt försämrad framförhållning i planeringen av drivningarna och dels förbättringar i form av bättre förarmiljö och höjd driftssäkerhet hos maskinerna. Granskningen, med viss komplettering av empirin, har också gett möjligheter till nyansering och utvidgning av mina tolkningar. Analysen i denna efterskrift har riktats mera mot helheten i arbetet och två diagnosmodeller har skapats med syfte att nå ökad förståelse av humankvalitetens variation och därmed underlätta inriktningen av förbättringsåtgärder. Den ena diagnosmodellen är en matris där man poängsätter fyra kritiska faktorer i organisationsmiljön – drivningsobjektens storlek och koncentration, arbetsresornas längd, skiftarbetets utformning och kontakten med produktionsledningen. Om organisationsmiljön för ett drivningslag får en låg totalpoäng är risken för vantrivsel och avhopp hos maskinförarna stor. Hög totalpoäng innebär stor sannolikhet för hög arbetsglädje i drivningslaget. Den andra diagnosmodellen identifierar två varianter av ekonomisk situation i den typiska entreprenörverksamheten; som består av en (eller två) maskingrupp(er) (skördare + skotare) där entreprenören kör maskin på heltid. Den ena varianten är en ond cirkel där entreprenören startade verksamheten med stora lån som ligger kvar på en hög nivå på grund av den svaga lönsamheten i verksamheten. Försöken att öka lönsamheten genom att pressa kostnaderna äts upp av kundernas återkommande sänkningar av kubikmeterpriset samtidigt med att man lägger på entreprenören nya uppgifter utan adekvat ersättning. Cirkeln blir lätt en ond spiral, men för den som inte orkar längre och vill lägga ned verksamheten blir lånenivån ett hinder. Den som försöker undvika lånefällan genom att avstå från förnyelse av maskinparken missar den produktivitetsökning som normalt följer med en ny maskin och får i stället arbeta hårdare och längre för att överleva. Den andra varianten är en god cirkel där företaget har en god och stabil ekonomi som medger relativt täta byten av maskiner – med allt bättre prestationsförmåga, förarmiljö och driftssäkerhet - utan att företaget drar på sig stora lån. Företaget tar sig lättare igenom uppkommande problem, ofta beroende på att godcirkelföretaget lättare lockar till sig högpresterande personal. Kopplar man ihop de båda diagnosmodellerna kan man lättare förstå den mycket stora spridningen i entreprenörernas och maskinförarnas inställning till det maskinella drivningsarbetet. Kombinationen av godcirkelföretag och god organisationsmiljö – som troligen ofta hänger samman – bäddar för mycket hög humankvalitet. De företag som rör sig i den onda cirkeln och erbjuds dåliga organisationsmiljöer hamnar lätt i en ond spiral som leder till vantrivsel, personalavhopp och utslagning. Det finns indikationer på att antalet onda cirklar och spiraler ökat bland drivningsentreprenörerna under de senaste två årens lågkonjunktur och att därmed hela drivningssektorn befinner sig i en ond spiral. I denna svacka förlorar sektorn resurser som det blir svårt att remobilisera när konjunkturen vänder.
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| 12. |
- Ahmed, Sheikh Ali, Senior Lecturer, 1977-, et al.
(författare)
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Anatomical, Physical, Chemical, and Biological Durability Properties of Two Rattan Species of Different Diameter Classes
- 2022
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Ingår i: Forests. - Switzerland : MDPI. - 1999-4907. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Rattan cane is an important forest product with economic value. Its anatomical, physical, and biological properties vary with the cane height. This makes it difficult to select the appropriate cane diameter for harvesting. Understanding the material properties of rattan cane with different diameter sizes is important to enhance its utilization and performance for different end uses. Thus, the present study was performed on two rattan species, Calamus zollingeri and Calamus ornatus, at two different cane heights (bottom/mature and top/juvenile). Calamus zollingeri was studied at diameter classes of 20 mm and 30 mm, while Calamus ornatus was analyzed at a diameter class of 15 mm. The anatomical properties, basic density, volumetric swelling, dynamic moisture sorption, and biological durability of rattan samples were studied. The results showed that C. zollingeri with a 20 mm diameter exhibited the highest basic density, hydrophobicity, dimensional stability, and durability against mold and white-rot (Trametes versicolor) fungi. As confirmed by anatomical studies, this could be due to the higher vascular bundle frequency and longer thick-walled fibers that led to a denser structure than in the other categories. In addition, the lignin content might have a positive effect on the mass loss of different rattan canes caused by white-rot decay.
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| 13. |
- Amiandamhen, Stephen, 1983-, et al.
(författare)
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Bioenergy production and utilization in different sectors in Sweden: A state of the art review
- 2020
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Ingår i: BioResources. - : University of North Carolina Press. - 1930-2126. ; 15:4, s. 9834-9857
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Forskningsöversikt (refereegranskat)abstract
- In the continual desire to reduce the environmental footprints of human activities, research efforts to provide cleaner energy is increasingly becoming vital. The effect of climate change on present and future existence, sustainable processes, and utilizations of renewable resources have been active topics within international discourse. In order to reduce the greenhouse gases emissions from traditional materials and processes, there has been a shift to more environmental friendly alternatives. The conversion of biomass to bioenergy, including biofuels has been considered to contribute to the future of climate change mitigation, although there are concerns about carbon balance from forest utilization. Bioenergy accounts for more than one-third of all energy used in Sweden and biomass has provided about 60% of the fuel for district heating. Apart from heat and electricity supply, the transport sector, with about 30% of global energy use, has a significant role in a sustainable bioenergy system. This review presents the state of the art in the Swedish bioenergy sector based on literature and Swedish Energy Agency’s current statistics. The review also discusses the overall bioenergy production and utilization in different sectors in Sweden. The current potential, challenges, and environmental considerations of bioenergy production are also discussed.
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| 14. |
- Ander, Paul, et al.
(författare)
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Sub-project 10: CRUW Mechanical Pulping Enzyme treatment of chips for energy reduction in TMP
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In order to evaluate the possibilities of using enzymes for pre-treating softwood chips as a means of lowering the energy demand in mechanical pulping, impregnation and refining trials were performed using a set of different enzymes. The enzymes tested pectinase, xylanase and mannanase gave increased sugar release in the impregnation trials indicating that most of the sugar released occurred in the first 60 minutes and that activities thereafter seemed to level off. Refining trials using a small Wing refiner showed that for chips treated for 60 minutes with pectinase, xylanase and mannanase no energy savings to a given freeness level was observed. The property development was similar to that of reference pulps in the case of pectinase and xylanase while for chips treated with mannanase a less favourable development of the tensile index was noted. For chips treated for two hours, using xylanase or pectinase, energy savings could be observed for pectinase treated chips down to a freeness level of 200 CSF. However when refined further, the properties approached those of the reference pulp. Considering the much higher enzymatic activity reached when the initial fibre material was further disintegrated it is assumed that the possibilities for enzymes to attack desired structures of the intact fibre wall may have been too few even in the case of Impressafiner treated material.
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| 15. |
- Andersson, Johanna, et al.
(författare)
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Comparison of steaming and boiling of root vegetables for enhancing carbohydrate content and sensory profile
- 2022
-
Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 312
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Tidskriftsartikel (refereegranskat)abstract
- Root vegetables have unique techno-functional and nutritional properties however, their use in processed foods is limited to a few species, partially due to a lack of knowledge related to the impact of thermal treatments on the sensory properties. This study investigated the effect of steaming and boiling on the microstructure, mechanical properties, and sensory profile of three model root vegetables with distinct carbohydrate composition: Jerusalem artichoke (Helianthus tuberosus L.), parsnip (Pastinaca sativa), and beetroot (Beta vulgaris). Thermally treated Jerusalem artichoke and parsnip showed higher content of cell wall polysaccharides, particularly β-glucans (e.g. cellulose) and pectic components, compared to raw. Steaming produced more cell shrinkage and loss of cell-cell adhesion than boiling, leading to softer vegetables. Processed beetroot showed loss of cell turgor and drastic softening but not clear changes in overall carbohydrate content. The scores for several flavour and in-mouth attributes were higher for steamed vegetables compared to boiled. Our results give insights on the processability of root vegetables towards products with enhanced sensory and nutritional properties.
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| 16. |
- Anerud, Erik
(författare)
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An alternative supply system for stump biomass - coarse grinding combined with sieving of the produced hog fuel
- 2016
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 27, s. 109-114
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Tidskriftsartikel (refereegranskat)abstract
- Transport costs are one of the major costs in the supply chain of stumps for fuel. Stump parts are bulkyand it is impossible to achieve full tonnages on trucks and trailers even though the load space iscompletely full. The transport economy for stumps is also negatively affected by the large amount ofcontaminants in the loads. Grinding the stumps at the landing and sieving of the produced hog fuel hasthe potential to increase load weights and reduce both the amount of contaminants and the transportcosts. To evaluate such a system a series of studies were made. Results show that coarse grinding andsieving reduced both moisture and ash content in the produced fuel, thus increasing the heating valueper ton delivered fuel and transforming a soil contaminated material to an acceptable fuel. Transportpayloads increased substantially compared to transports of stump parts, but a transport distance of110 km was needed before the coarse grinding system provided lower cost than the standard systemwith transports of stump parts and grinding at the heating plant. Further studies are needed to evaluatethe total energy efficiency in the two systems. Coarse grinding and sieving is a feasible way to increasefuel quality and improve transport economy. However, total costs will in most cases be higher than forthe loose stump system which renders the method preferable only in cases where the sieving processconverts a non-acceptable material into an acceptable fuel.
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| 17. |
- Axelsson, Anna-Lena, et al.
(författare)
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Att jämföra skogens då med nu
- 2011
-
Ingår i: Miljötrender från SLU. - 1403-4743. ; , s. 3-5
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 18. |
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| 19. |
- Bergström, Dan, et al.
(författare)
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Quality and productivity in comminution of small-diameter tree bundles
- 2016
-
Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 27, s. 179-187
-
Tidskriftsartikel (refereegranskat)abstract
- Bundling small-diameter trees from thinnings has become a viable technology with the development of the Fixteri harvester-bundler. Several studies have measured the productivity of the machine, however, bundling also influences the whole supply chain. A study was conducted to investigate the quality of chips and productivity of five different conventional chippers and one grinder when comminuting bundles produced of small-diameter trees. The productivity based on dry mass was on average 44.8 tonne per effective working hour (E-0 H-1), and varied considerably between the machines; 1:2.3 being the observed relation between lowest and highest performance of machines. Productivity when comminuting bundles was 1.5-3.2 times higher than normally found in the literature for unbundled (loose) material. The quality of the produced fuel chips varied between machines in dry weight share of particle sizes <3.15 mm from around 5 to 35%. The average size of the chips varied between 5 and 20 mm. The study indicated that productivity and quality of fuel chips are dependent on machine type and the raw material processed. Further investigations should examine different machine systems in designed experiments where e.g. several assortments and operational environments are included.
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| 20. |
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| 21. |
- Bonarski, Jan T., et al.
(författare)
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Effects of cell wall ultrastructure on the transverseshrinkage anisotropy of Scots pine wood
- 2015
-
Ingår i: Holzforschung. - : Walter de Gruyter. - 0018-3830 .- 1437-434X. ; 69:4, s. 501-507
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Tidskriftsartikel (refereegranskat)abstract
- A hypothesis for explaining the differential anisotropicshrinkage behavior of wood has been proposed,and it was based on the differences in the cell wall ultrastructure.The starting point of the consideration is thatwood shrinkage is governed by its chemical composition,ultrastructure, and gross anatomy. It is also well knownthat the transverse shrinkage anisotropy of earlywood(EW) is more pronounced than that of the latewood (LW).In the paper, the cell wall ultrastructure and shrinkageanisotropy has been related to each other, and to thispurpose, a set of crystallographic texture descriptorswas applied. The descriptors are based on X-ray diffraction(XRD) experiments conducted on matched EW samplesfrom different growth rings of Scots pine. The rangeof the microfibril angle (MFA) was identified. The ratio ofthe maxima of inverse pole figures (IPFs) of both the tangential(T) and radial (R) directions was determined. Theratios quantify the inhomogeneity of the spatial arrangementof the ordered areas. The results of the study clearlyindicate that the transverse shrinkage of wood is governedmostly by a specific ultrastructural organization of moderatelyorganized cell wall compounds.
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| 22. |
- Chen, Zhiqiang, et al.
(författare)
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Method for accurate fiber length determination from increment cores for large-scale population analyses in Norway spruce
- 2016
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70:9, s. 829-838
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Tidskriftsartikel (refereegranskat)abstract
- Fiber (tracheid) length is an important trait targeted for genetic and silvicultural improvement. Such studies require large-scale non-destructive sampling, and accurate length determination. The standard procedure for non-destructive sampling is to collect increment cores, singularize their cells by maceration, measure them with optical analyzer and apply various corrections to suppress influence of non-fiber particles and cut fibers, as fibers are cut by the corer. The recently developed expectation-maximization method (EM) not only addresses the problem of non-fibers and cut fibers, but also corrects for the sampling bias. Here, the performance of the EM method has been evaluated by comparing it with length-weighing and squared length-weighing, both implemented in fiber analyzers, and with microscopy data for intact fibers, corrected for sampling bias, as the reference. This was done for 12-mm increment cores from 16 Norway spruce (Picea abies (L.) Karst) trees on fibers from rings 8-11 (counted from pith), representing juvenile wood of interest in breeding programs. The EM-estimates provided mean-fiber-lengths with bias of only +2.7% and low scatter. Length-weighing and length2-weighing gave biases of-7.3% and +9.3%, respectively, and larger scatter. The suggested EM approach constitutes a more accurate non-destructive method for fiber length (FL) determination, expected to be applicable also to other conifers.
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| 23. |
- Chen, Zhi-Qiang, et al.
(författare)
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Estimating solid wood properties using Pilodyn and acoustic velocity on standing trees of Norway spruce
- 2015
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Ingår i: Annals of Forest Science. - : Springer Science and Business Media LLC. - 1286-4560 .- 1297-966X. ; 72:4, s. 499-508
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Tidskriftsartikel (refereegranskat)abstract
- Key message: Strong genetic correlations were observed between Pilodyn measurement and wood density, and between acoustic velocity and MFA. Combination of Pilodyn penetration and acoustic velocity measurements from standing trees can provide reliable prediction of stiffness of Norway spruce for breeding selection.Context: Traditional methods for the estimation of solid wood quality traits of standing tree such as wood density, microfibril angle (MFA), and modulus of elasticity (MOE) are time-consuming and expensive, which render them unsuitable for rapidly screening a large number of trees in tree breeding programs.Aim: This study aims to evaluate the suitability of using Pilodyn penetration and acoustic velocity (nondestructive evaluation) to assess wood density, MFA, and MOE for Norway spruce.Methods: Pilodyn penetration and Hitman acoustic velocity, as well as wood density, MFA, and MOE using benchmark SilviScan were measured on 5618 standing trees of 524 open-pollinated families in two 21-year-old Norway spruce (Picea abies) progeny trials in southern Sweden.Results: Strong genetic correlations were observed between Pilodyn measurement and wood density (rg = −0.96), and between acoustic velocity and MFA (rg = −0.94). Combination of Pilodyn penetration and Hitman acoustic velocity measurements (Formula presented.) obtained from standing trees showed a genetic correlation with benchmark MOE of 0.99. This combined MOE(Formula presented.) had higher selection efficiency for benchmark MOE (92 %) compared to 58–60 % using acoustic velocity alone and 78 % using Pilodyn penetration alone.Conclusion: Combination of Pilodyn penetration with Hitman acoustic velocity provided very high selection efficiency for the three most important quality traits for wood mechanical properties in Norway spruce.
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| 24. |
- Chen, Zhi-Qiang, et al.
(författare)
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Genetic analysis of fiber dimensions and their correlation with stem diameter and solid-wood properties in Norway spruce
- 2016
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Ingår i: Tree Genetics & Genomes. - : Springer Science and Business Media LLC. - 1614-2942 .- 1614-2950. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- Adverse genetic correlations between growth traits and solid-wood, as well as fiber traits are a concern in conifer breeding programs. To evaluate the impact of selection for growth and solid-wood properties on fiber dimensions, we investigated the inheritance and efficiency of early selection for different wood-fiber traits and their correlations with stem diameter, wood density, modulus of elasticity (MOE), and microfibril angle (MFA) in Norway spruce (Picea abies L). The study was based on two large open-pollinated progeny trials established in southern Sweden in 1990 with material from 524 families comprising 5618 trees. Two increment cores were sampled from each tree. Radial variations from pith to bark were determined for rings 3–15 with SilviScan for fiber widths in the radial (RFW) and tangential (TFW) direction, fiber wall thickness (FWT), and fiber coarseness (FC). Fiber length (FL) was determined for rings 8–11. Heritabilities based on rings 8–11 using joint-site data were moderate to high (0.24–0.51) for all fiber-dimension traits. Heritabilities based on stem cross-sectional averages varied from 0.34 to 0.48 and reached a plateau at rings 6–9. The “age-age†genetic correlations for RFW, TFW, FWT, and FC cross-sectional averages at a particular age with cross-sectional averages at ring 15 reached 0.9 at rings 4–7. Our results indicated a moderate to high positive genetic correlation for density and MOE with FC and FWT, moderate and negative with RFW, and low with TFW and FL. Comparison of several selection scenarios indicated that the highest profitability is reached when diameter and MOE are considered jointly, in which case, the effect on any fiber dimension is negligible. Early selection was highly efficient from ring 5 for RFW and from rings 8–10 for TFW, FWT, and FC.
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| 25. |
- Chen, Zhiqiang
(författare)
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Quantitative genetics of Norway spruce in Sweden
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Genetic improvement of solid wood and pulp and paper products related wood quality traits are important to increase productivity and value of Norway spruce plantation in Sweden. To incorporate wood quality traits into Norway spruce tree breeding program, genetic parameters of solid wood and fibre traits were investigated in a large Norway spruce population. 524 half-sib families from two trials tested in southern Sweden were selected to characterise the genetic variation in wood density, microfibril angle (MFA), modulus of elasticity (MOE), radial fibre width (RFW), tangential fibre width (TFW), fibre wall thickness (FWT), fibre coarseness (FC), and fibre length (FL). To rapidly measure stiffness (MOE) of standing trees and accurately measure FL from increment cores, a new non-destructive method for quantifying stiffness and a new algorithm for calculating FL were developed. A combination of Pilodyn and acoustic Hitman measurement was found to predict stiffness of standing tree accurately and the new algorithm using Expectation-Maximization could accurately estimate FL. To improve the estimate of genetic parameters and understanding genotype by environment (G×E) interaction in Norway spruce, spatial analyses were applied to 145 progeny trials and factor-analytic method was applied to 20 half-sib progeny trials. Spatial analysis significantly improved heritability and accuracy of breeding value prediction. Frost damage may be a main driver for G×E interaction for tree height of Norway spruce in southern and central Sweden. Wood quality traits showed higher heritability than growth traits. However, growth traits had highly unfavourable genetic correlations with solid wood quality traits (0.54-0.75) and weakly to moderately unfavourable genetic correlations with fibre property traits (0.11-0.49). In conclusion, selection based on diameter alone would have considerable negative effects on wood quality traits, a negligible or small negative effect on FL, and only a moderate effect on FWT. A selection index combining diameter and stiffness, which would have minimal impact on FL, is recommended for spruce breeding. Adequate economic weights for growth and stiffness traits should be determined for Norway spruce breeding program to maximize economic gain for Norway spruce.
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