| 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. |
- Fundová, Irena
(författare)
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Quantitative genetics of wood quality traits in Scots pine
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wood quality of commercial tree species is important for many wood processingindustries and thus should be considered for inclusion in forest tree improvementprograms. This thesis evaluated the suitability of various proxy methods for rapid andnon-destructive assessment of wood quality traits on standing trees of Scots pine and thepotential for genetic improvement of different wood quality traits through recurrentselective breeding.Penetrometer Pilodyn and micro-drill Resistograph were tested for non-destructiveassessment of wood density (DENPIL and DENRES, respectively), using SilviScan density(DENSILV) as a benchmark. A strong additive genetic correlation was observed betweenDENSILV and DENRES (rA = 0.96), whilst the correlation with DENPIL was substantiallylower (rA = 0.74). Furthermore, SilviScan stiffness (MOESILV) was used as a benchmarkfor evaluation of several approaches of calculating the dynamic modulus of elasticity(MOE) from standing-tree acoustic velocity (VELTREE). The combination of VELTREEand adjusted DENRES provided the most accurate estimate of MOETREE (rA = 0.91).Additionally, non-destructive acoustic sensing tools were tested at different stages ofwood processing (on standing trees, felled logs and sawn boards) using destructivelymeasured sawn-board stiffness (static modulus of elasticity, MOES) and strength(modulus of rupture, MOR) as benchmarks. They proved to be capable of accuratelypredicting MOES (rA ≈ 0.8) while VELTREE, adjusted DENRES and MOETREE wellreflected MOR (rA ≈ 0.9). Genetic variation of shape stability of sawn boards (bow, crookand twist) was also investigated. Under-bark grain angle (GRA) was found to be a goodpredictor of sawn-board twisting and crooking (rA = 0.84 and 0.62, respectively). Thechemical composition of juvenile wood (proportion of cellulose, hemicelluloses, ligninand extractives) was predicted from Fourier transform infrared (FTIR) spectra usingpartial least squares regression (PLSR) modeling. Individual-tree narrow-senseheritabilities (ℎi2) for all of the studied wood quality traits varied from low to moderate.Genetic improvement of sawn-board DEN, MOES and MOR as the target traits couldbe achieved through selective breeding for MOETREE, DENRES, stem straightness (STR)or GRA. Selection focusing on GRA would also result in lower bow, crook and twist.Despite the negative genetic correlations between growth and wood quality traits, apossibility of their simultaneous improvement was identified. An index combining stemdiameter (DBH) and MOETREE provided the best compromise.
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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- 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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