| 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. |
- Scarfone, Antonio, et al.
(författare)
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Storage dynamics and fuel quality of poplar chips
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 62, s. 17-25
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Tidskriftsartikel (refereegranskat)abstract
- Poplar cultivation for wood/timber production has a growth production cycle of about 10-15 years. Usually the stem is separated from the crown and used to produce material of different kind such as veneer, pallets, panels, etc. For wood industries,. crowns generally represent waste material to be disposed of, causing economic and time losses. It is generally believed that the costs of managing crown biomass are higher than the potential incomes obtainable. Nonetheless, it is worthwhile investigating the possibility of using these byproducts as energy source and evaluating their value as a fuel. However, storing such residues presents several problems connected with spontaneous microbial degradation.The aim of this work was to evaluate the storage effects on chipped biomass deriving from the crown and stem wood of poplar and how they affect fuel quality and dry matter losses.A storage trial was carried out with three piles of stem wood chips and three of crown chips coming from a 15 year old poplar plantation. The piles were stored outdoors for six months under the same climatic conditions.The effect of storage on fuel quality was evaluated with respect to moisture content, gross and net calorific values, chemical composition, ash content, and bulk density.The variation of temperatures inside each pile due to heat development was continuously monitored and showed different trends between piles depending on source material. Results showed that chips from crown material had better storage properties and exhibited lower decay than chips from stem wood. (C) 2014 Elsevier Ltd. All rights reserved.
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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. |
- 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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| 8. |
- Ager, Bengt
(författare)
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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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| 9. |
- 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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| 10. |
- 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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