| 1. |
- Arshadi, Mehrdad, et al.
(author)
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Emission of Volatile Aldehydes and Ketones from Wood Pellets under Controlled Conditions
- 2009
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In: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 0003-4878 .- 1475-3162. ; 53, s. 797-805
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Journal article (peer-reviewed)abstract
- Different qualities of biofuel pellets were made from pine and spruce sawdust according to an industrial experimental design. The fatty/resin acid compositions were determined by gas chromatography-mass spectrometry for both newly produced pellets and those after 2 and 4 weeks of storage. The aldehydes/ketones compositions were determined by high performance liquid chromatography at 0, 2, and 4 weeks. The designs were analyzed for the response variables: total fatty/resin acids and total aldehydes/ketones. The design showed a strong correlation between the pine fraction in the pellets and the fatty/resin acid content but the influence decreased over storage time. The amount of fatty/resin acids decreased similar to 40% during 4 weeks. The influence of drying temperature on the aldehyde/ketone emission of fresh pellets was also shown. The amounts of emitted aldehydes/ketones generally decreased by 45% during storage as a consequence of fatty/resin acid oxidation. The matrices of individual concentrations were subjected to multivariate data analysis. This showed clustering of the different experimental runs and demonstrated the important mechanism of fatty/resin acid conversion.
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| 2. |
- Bergström, Dan, et al.
(author)
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Effects of Extractives on the Physical Characteristics of Scots Pine Sawdust Fuel Pellets
- 2010
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In: Forest Products Journal. - : Forest Products Society. - 0015-7473. ; 60, s. 640-644
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Journal article (peer-reviewed)abstract
- In order to evaluate the effect of extractives on particle bonding, pellets were produced from extracted and nonextracted Scots pine sawdust in a laboratory piston press pelletizer. In the experiment, the raw material and process parameters were fresh (nonextracted) and acetone-extracted sawdust, sawdust moisture content (6% and 12%), piston pressure (70 and 150 MPa), and press temperature (1008C and 1808C). The resulting pellets were evaluated and compared for density, compression strength, and moisture sorption. The relationship between factors and responses was evaluated by partial least squares regression. In the present study, it was found that pressure and temperature had a positive effect on both pellet density and compression strength. Extracted sawdust gave pellets with a higher density and compression strength than pellets made from nonextracted sawdust. Moisture sorption between the produced pellets showed no significant differences. Results of this study provide a plausible explanation for why pellets produced from stored sawdust with low amounts of extractives have better strength properties than pellets produced from fresh sawdust
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| 3. |
- Bergström, Dan, et al.
(author)
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Effects of raw material particle size distribution on the characteristics of Scots pine sawdust fuel pellets
- 2008
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In: Fuel processing technology. - Amsterdam : Elsevier. - 0378-3820 .- 1873-7188. ; 89:12, s. 1324-1329
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Journal article (peer-reviewed)abstract
- In order to study the influence of raw material particle size distribution on the pelletizing process and the physical and thermomechanical characteristics of typical fuel pellets, saw dust of Scots pine was used as raw material for producing pellets in a semi industrial scaled mill (similar to 300 kg h(-1)). The raw materials were screened to a narrow particle size distribution and mixed into four different batches and then pelletized under controlled conditions. Physical pellet characteristics like compression strength, densities, moisture content, moisture absorption and abrasion resistance were determined. In addition, the thermochemical characteristics, i.e. drying and initial pyrolysis, flaming pyrolysis, char combustion and char yield were determined at different experimental conditions by using a laboratory-scaled furnace. The results indicate that the particle size distribution had some effect on current consumption and compression strength but no evident effect on single pellet and bulk density, moisture content, moisture absorption during storage and abrasion resistance. Differences in average total conversion time determined for pellet batches tested under the same combustion conditions was less than 5% and not significant. The results are of practical importance suggesting that grinding of saw dust particle sizes below 8 mm is probably needless when producing softwood pellets. Thus it seem that less energy could be used if only over sized particles are grinded before pelletizing.
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| 4. |
- Finell, Michael, et al.
(author)
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Carbohydrate composition in delayed harvested reed canary grass
- 2011
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In: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 35, s. 1097-1102
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Journal article (peer-reviewed)abstract
- Reed canary grass (Phalaris arundinacea L.) samples of the Palaton variety grown at 10 different locations in northern Europe were analyzed and the effect of growing location and soil type on the carbohydrate composition and lignin content were investigated. The results showed that the major carbohydrate components in delayed harvested reed canary grass were glucose and xylose. Some growing locations and soil types significantly influenced the carbohydrate composition of the grass. Soils with both high organic and clay content produced lower glucose and xylose contents but an increased lignin content. A soil rich in sand gave higher glucose, xylose and arabinose content. Reed canary grass is a perennial rhizome grass that has shown potential as an energy crop for solid bio-fuel production and as a short fibre raw material for the pulp and paper industry. This study showed that delayed harvested reed canary grass can also be a potential new raw material for ethanol production
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| 5. |
- Finell, Michael, et al.
(author)
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Laboratory-scale production of biofuel pellets from electron beam treated Scots pine (Pinus silvestris L.) sawdust
- 2009
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In: Radiation Physics and Chemistry. - : Elsevier BV. - 0969-806X. ; 78, s. 281-287
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Journal article (peer-reviewed)abstract
- The effect of electron beam (EB) treatment on pine sawdust used as raw material for fuel pellets was studied. Dry sawdust was EB treated at different dosage levels up to 100 kGy. The effect of EB treatment on fatty and resin acid composition was studied for different dosage levels and compared to untreated sawdust. Pellets were pressed in a laboratory single pellet press unit according to a D-optimal, response surface modeling (RSM) experimental design, where sawdust moisture content and die temperature were varied independently for EB treatment dosages of 0, 18.2 and 48.9 kGy. The responses of the designed experiment were density and strength for the produced pellets. The results showed that the free fatty and resin acid content in the sawdust initially decreased with increasing EB doses but at the highest EB doses it increased. The total content of extractives however initially increased and then decreased with increasing EB dose. Pellets made of EB treated sawdust had a significantly (at 95% confidence level) higher density and compressive strength than pellets made from untreated sawdust. EB treated sawdust behaved similarly to stored (mature) sawdust as a pellet raw material. Thus, EB treatment opens the possibility for controlled ageing (maturation) of pellet raw materials.
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| 6. |
- Gref, Rolf, 1944-, et al.
(author)
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Influence of wood extractives on brown and white rot decay in Scots pine heart-, light- and sapwood
- 2000
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In: Material und Organismen. - Berlin : Duncker & Humblot. - 0025-5270. ; 33:2, s. 119-128
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Journal article (peer-reviewed)abstract
- The influence of wood extractives such as free fatty and resin acids, pinosylvin, steryl esters and triglycerids in sapwood, heartwood and induced lightwood of Scots pine, Pinus sylvestris L., on decay resistance against Postia placenta and Phanerochaete chrysosporium was investigated. After incubation periods of 38 and 42 days for the brown and white rot, respectively, the wood blocks were weighed and the weight losses of the blocks were correlated to the chemical composition of the wood types. Both fungi decayed the sapwood at a greater rate than they did the heartwood and the lightwood. - If the weight losses are compared to the chemical composition it is obvious that the losses caused by both fungi are lower in the wood tissues with high levels of pinosylvin and/or resin acids. It was concluded that pinosylvin alone cannot be responsible for decay resistance in the heartwood and the lightwood. Most probably resin acids are also important factors in decay resistance in the heartwood and the lightwood. Most probably resin acids are also important factors in decay resistance because they act as waterproofing layers thus retarding the entrance of the decay fungi. - The results from the present work also suggest that triglycerides are important factors in wood decay. In wood with low decay resistance triglycerids accounted for 60-70 % of total lipids while the corresponding value for those with high resistance was about 1 %. Obviously the inhibitory effects of pinosylvin and resin acids might be overcome if nutrients like triglycerides are available in the wood.
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| 7. |
- Kwamin, Francis, et al.
(author)
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Interactions of extracts from selected chewing stick sources with Aggregatibacter actinomycetemcomitans
- 2012
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In: BMC Research Notes. - : BioMed Central. - 1756-0500. ; 5, s. 203-
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Journal article (peer-reviewed)abstract
- BACKGROUND: Aggregatibacter actinomycetemcomitans produces a leukotoxin that activates a pro-inflammatory death of human monocytes/macrophages. A specific clone of this bacterium (JP2) has a 530-base pair deletion in the leukotoxin promoter gene that causes a significantly enhanced expression of leukotoxin. This specific clone of A. actinomycetemcomitans is common in some African populations and has a strong association with periodontal attachment loss in adolescents in these populations. Chewing sticks of plant origin are commonly used as oral hygiene tool in Africa, but their role as a therapeutic agent in periodontal disease is poorly investigated. RESULTS: Ethanol extracts were made from 7 common plants used as chewing sticks in West-Africa. None of the tested extracts inhibited growth of A. actinomycetemcomitans. However, extracts from Psidium guajava (Guava) completely neutralized the cell death and pro-inflammatory response of human leukocytes induced by the leukotoxin. None of the six other tested chewing stick extracts showed this effect. CONCLUSIONS: The discovery that extracts from Guava efficiently neutralizes A. actinomycetemcomitans leukotoxicity might lead to novel therapeutic agents and strategies for prevention and treatment of aggressive forms of periodontitis induced by infections with the highly leukotoxic JP2 clone of this bacterium.
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| 8. |
- Martin, Björn, et al.
(author)
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Identification of the photosynthetic co2 fixation inhibitors in isolated pine chloroplasts as resin acids
- 1984
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In: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 62:1, s. 110-114
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Journal article (peer-reviewed)abstract
- Thus far all attempts to isolate CO, fixing chloroplasts from pine have failed. In this paper it is proposed that resin acids present in pine needles partition into membranes during chloroplast isolation and interfere with specific reactions of the Calvin cycle. CO, fixation by isolated spinach chloroplasts was strongly inhibited by the introduction of a suspension of chloroplasts isolated from Pinus sylvestris L. A partially purified organic extract obtained from chloroplasts of this pine species also strongly inhibited CO, fixation by the spinach chloroplasts. The major inhibitory compounds from the organic extract were identified as a mixture of resin acids by gas-liquid chromatography and mass spectrometry. Two resin acids, abietic acid and dehydroabietic acid, were tested for inhibitory activity. Both resin acids were potent inhibitors of photosynthetic CO2fixation, with dehydroabietic acid being about three times more potent than abietic acid.
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| 9. |
- Rhén, Christofer, et al.
(author)
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Effect of raw material composition in woody biomass pellets on combustion characteristics
- 2007
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In: Biomass and Bioenergy. - Oxford : Pergamon Press. - 0961-9534 .- 1873-2909. ; 31:1, s. 66-72
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Journal article (peer-reviewed)abstract
- Char yield, char combustion time and char combustion rate of pellets made from different tree parts of Norway spruce and industrially made stem wood pellets of Norway spruce and Scots pine were studied. The pellets were incinerated in a laboratory scale oven at various temperatures, gas flows and oxygen concentrations. It was found that the combustion time for a single pellet mostly depended on the raw material composition and to a minor extent on the density. Pellets made of bark had up to a 50% longer char combustion time compared to that of stem wood pellets, due to differences in char yield. Industrially made stem wood pellets of pine and spruce sawdust were found to have small differences in combustion characteristics. The variations in combustion characteristics of pellets are discussed in relation to composition of raw material.
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| 10. |
- Rhen, Christofer, et al.
(author)
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Effects of raw material moisture content, densification pressure and temperature on some properties of Norway spruce pellets
- 2005
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In: FUEL PROCESSING TECHNOLOGY. - : Elsevier BV. - 0378-3820. ; 87:1, s. 11-16
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Journal article (peer-reviewed)abstract
- In order to study the pelletising process, Norway spruce sawdust pellets were produced under strictly controlled conditions on a laboratory scale. The aim of the work was to investigate how the moisture content of raw material and the densification parameters, pressure and temperature, affect compression strength, dry density and moisture uptake of the formed pellets. In the experiments performed, temperature (26–144 °C), moisture content (6.3–14.7 wt.% of d.b.) and pressure (46–114 MPa) were the factors which varied according to a prescribed central composite design. The relationships between the factor settings and the responses (dry density, moisture uptake and compression strength) were evaluated by multiple linear regressions.In the present study, it was found that high compression strength was strongly correlated with the density of the pellets. High temperature (at least up to 144 °C) and low moisture content at the start of compression (down to 6.3 wt.% of d.b.) increased the dry density of the pellets. Remarkably, compression force had very little effect in the tested range of 46–114 MPa, indicating that pressure in the die does not need to be higher than 50 MPa.Similarly, compression force had very little effect on moisture uptake in the pellets. The least moisture uptake occurred when the pellets were produced at 90 °C.
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