| 1. |
- Alriksson, Björn, et al.
(författare)
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Improving the fermentability of enzymatic hydrolysates of lignocellulose through chemical in-situ detoxification with reducing agents
- 2011
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Ingår i: Bioresource Technology. - : Elsevier Ltd. - 0960-8524 .- 1873-2976. ; 102:2, s. 1254-1263
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Tidskriftsartikel (refereegranskat)abstract
- Inhibitory lignocellulose hydrolysates were treated with the reducing agents dithionite and sulfite to achieve improved fermentability. Addition of these reducing agents (in the concentration range 5.0-17.5mM) to enzymatic hydrolysates of spruce wood or sugarcane bagasse improved processes based on both SHF (simultaneous hydrolysis and fermentation) and SSF (simultaneous saccharification and fermentation). The approach was exemplified in ethanolic fermentations with Saccharomyces cerevisiae and by using hydrolysates with sugar concentrations >100g/L (for SHF) and with 10% dry-matter content (for SSF). In the SHF experiments, treatments with dithionite raised the ethanol productivities of the spruce hydrolysate from 0.2 to 2.5g×L(-1)×h(-1) and of the bagasse hydrolysate from 0.9 to 3.9g×L(-1)×h(-1), values even higher than those of fermentations with reference sugar solutions without inhibitors. Benefits of the approach include that the addition of the reducing agent can be made in-situ directly in the fermentation vessel, that the treatment can be performed at a temperature and pH suitable for fermentation, and that the treatment results in dramatically improved fermentability without degradation of fermentable sugars. The many benefits and the simplicity of the approach offer a new way to achieve more efficient manufacture of fermentation products from lignocellulose hydrolysates.
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| 2. |
- Bergström, Jenny, et al.
(författare)
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Becoming materials : material forms and forms of practice
- 2010
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Ingår i: Digital Creativity. - : Routledge. - 1462-6268 .- 1744-3806. ; 21:3, s. 155-172
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Tidskriftsartikel (refereegranskat)abstract
- As a result of development toward ‘smart’ materials, materials now enable an expanding range of aesthetic expressions and user experiences. These materials are fundamentally temporal in their capacity to assume multiple, discrete states of expression that can be repeatedly and minutely controlled. These materials come to be, or become, only over time and in context—they are becoming materials. Thus, in the development and application of such materials, we must engage more extensively with the experience of materials in practices of design and of use. This paper introduces and discusses the concept of becoming materials—as well as the implications for practice—through a series of examples from our own practice-led research within art, design and architecture. Coming to terms with the implications for material practices of design and of use, we suggest, requires the development of new concepts and methods for doing and studying the design of becoming materials.
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| 3. |
- Boman, Christoffer, et al.
(författare)
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Stove performance and emission characteristics in residential wood log and pellet combustion : Part 1: Pellet stoves
- 2011
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 25:1, s. 307-314
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Tidskriftsartikel (refereegranskat)abstract
- Stove performance, characteristics and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter and chimney draught. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NOx, organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PMtot and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene and benzene and the emissions of VOC varied in the range 1.1-47 mg/MJfuel. PAH emissions (2-340 µg/MJfuel) were generally dominated by phenantrene, fluoranthene and pyrene. PMtot (15-45 mg/MJfuel) were in all cases dominated by fine particles with mass median diameters in the range 100-200 nm, peak mobility diameters of 50-85 nm and number concentrations in the range 4×1013- 3×1014 particles/MJfuel. During high load conditions the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJfuel consisting of potassium, sodium, sulfur and chlorine, in the form of K2SO4, K3Na(SO4)2 and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data.
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| 4. |
- Cavka, Adnan, et al.
(författare)
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Biorefining of wood : combined production of ethanol and xylanase from waste fiber sludge
- 2011
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Ingår i: Journal of Industrial Microbiology & Biotechnology. - : Springer. - 1367-5435 .- 1476-5535. ; 38:8, s. 891-899
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Tidskriftsartikel (refereegranskat)abstract
- The possibility to utilize fiber sludge, waste fibers from pulp mills and lignocellulose-based biorefineries, for combined production of liquid biofuel and biocatalysts was investigated. Without pretreatment, fiber sludge was hydrolyzed enzymatically to monosaccharides, mainly glucose and xylose. In the first of two sequential fermentation steps, the fiber sludge hydrolysate was fermented to cellulosic ethanol with the yeast Saccharomyces cerevisiae. Although the final ethanol yields were similar, the ethanol productivity after 9.5 h was 3.3 g/l/h for the fiber sludge hydrolysate compared with only 2.2 g/l/h for a reference fermentation with similar sugar content. In the second fermentation step, the spent fiber sludge hydrolysate (the stillage obtained after distillation) was used as growth medium for recombinant Aspergillus niger expressing the xylanase-encoding Trichoderma reesei (Hypocrea jecorina) xyn2 gene. The xylanase activity obtained with the spent fiber sludge hydrolysate (8,500 nkat/ml) was higher than that obtained in a standard medium with similar monosaccharide content (1,400 nkat/ml). Analyses based on deglycosylation with N-glycosidase F suggest that the main part of the recombinant xylanase was unglycosylated and had molecular mass of 20.7 kDa, while a minor part had N-linked glycosylation and molecular mass of 23.6 kDa. Chemical analyses of the growth medium showed that important carbon sources in the spent fiber sludge hydrolysate included xylose, small aliphatic acids, and oligosaccharides. The results show the potential of converting waste fiber sludge to liquid biofuel and enzymes as coproducts in lignocellulose-based biorefineries.
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| 5. |
- Cavka, Adnan, et al.
(författare)
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Effect of sulfur oxyanions on lignocellulose-derived fermentation inhibitors
- 2011
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 108:11, s. 2592-2599
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Tidskriftsartikel (refereegranskat)abstract
- Recent results show that treatments with reducing agents, including the sulfur oxyanions dithionite and hydrogen sulfite, efficiently improve the fermentability of inhibitory lignocellulose hydrolysates, and that the treatments are effective when the reducing agents are added in situ into the fermentation vessel at low temperature. In the present investigation, dithionite was added to medium with model inhibitors (coniferyl aldehyde, furfural, 5-hydroxymethylfurfural, or acetic acid) and the effects on the fermentability with yeast were studied. Addition of 10 mM dithionite to medium containing 2.5 mM coniferyl aldehyde resulted in a nine-fold increase in the glucose consumption rate and a three-fold increase in the ethanol yield. To investigate the mechanism behind the positive effects of adding sulfur oxyanions, mixtures containing 2.5 mM of a model inhibitor (an aromatic compound, a furan aldehyde, or an aliphatic acid) and 15 mM dithionite or hydrogen sulfite were analyzed using mass spectrometry (MS). The results of the analyses, which were performed by using UHPLC-ESI-TOF-MS and UHPLC-LTQ/Orbitrap-MS/MS, indicate that the positive effects of sulfur oxyanions are primarily due to their capability to react with and sulfonate inhibitory aromatic compounds and furan aldehydes at low temperature and slightly acidic pH (such as 25°C and pH 5.5).
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| 6. |
- Clark, Brendon, et al.
(författare)
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Språkskap : Supporting Second Language Learning “In the Wild”
- 2011
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Ingår i: INCLUDE 2011 Proceedings. - London : Royal College of Art. - 9781907342295 ; , s. 985-994
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Konferensbidrag (refereegranskat)abstract
- Teaching second languages behind closed classroom doors means to ignore one of the most powerful resources available: language use in everyday social interactions in the surrounding society. Although modern language teaching methodology since the beginning of the 20th century has centered on language use (model dialogs, communicative tasks, role plays and needs analysis) the ‘wild’ and unplanable life in Language Two has rarely been employed as a systematic resource for the acquisition of the new language. This paper introduces a Swedish language design project that explores introducing temporary material and conceptual structures to support turning everyday encounters between Swedish learners and speakers into learning situations. Appreciating the social and situated nature of language learning opens for a whole range of actors, tools and environments to support the learning endeavor. We introduce pillars for extending learning support beyond the classroom setting into the interactions of private and public sphere.
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| 7. |
- Ekevad, Mats, et al.
(författare)
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Drying shrinkage of sawn timber of Norway spruce (Picea abies) : industrial measurements and finite element simulations
- 2011
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Ingår i: Wood Material Science & Engineering. - London : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 6:1, s. 41-48
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Tidskriftsartikel (refereegranskat)abstract
- Industrial measurements of green and dry cross-section dimensions were performed for 189 Norway spruce (Picea abies) centre-yield boards with dry dimensions 51x49 mm. Two, three or four boards were sawn from each log, depending on log size. Different approaches were used for simulations of cross-section shrinkage during drying. An analytical model, an elastic, an elastic mechanosorptive and an elastic plastic finite element simulation model were tested. Thickness and width shrinkage and deformation were simulated. Shrinkage results were compared with each other and with the experimental results. All simulation models gave roughly the same degree of agreement with experimental results except for the centre board from the three-board sawing pattern. For the other boards, the analytical model was not generally better or worse than the results from the finite element models. Shrinkage deformations in finite element models that included mechanosorption or plasticity were nearly the same as for the elastic finite element model except for the centre board of the three-board sawing pattern. The mechanosorptive model was the best model for the shrinkage of the centre board of this sawing pattern except for mid-thickness shrinkage. Comparison between the different finite element simulation models of stresses in the centre board revealed large differences.
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| 8. |
- Pettersson, Esbjörn, et al.
(författare)
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Design changes in a fixed bed pellet combustion device : effects of temperature and residence time on emission performance
- 2010
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 24:2, s. 1333-1340
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Tidskriftsartikel (refereegranskat)abstract
- The use of wood fuel pellets has proven to be well-suited for the small-scale market, enabling controlled and efficient combustion with low emission of products of incomplete combustion (PIC). Still, a potential for further emission reduction exists, and a thorough understanding of the influence of combustion conditions on the emission characteristics of air pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM), is important. The objective of the present work was to determine the effect of design changes, i.e., increasing the temperature and/or residence time, on the emission performance and characteristics for a pellet combustion device using a laboratory fixed-bed reactor (<5 kW). The temperature and residence time after the bed section were varied according to statistical experimental designs (650-950 °C and 0.5-3.0 s) with the emission responses: CO, organic gaseous carbon (OGC), NO, volatile organic compounds (VOCs, 20 compounds), PAHs (43 compounds), PMtot mass concentration, fine particle mass/count median diameter (MMD and CMD), and number concentration. The temperature was negatively correlated with the emissions of all studied PIC, with limited effects of the residence time. The PMtot emissions of 15-20 mg/MJ were in all cases dominated by fine (<1 μm) particles of K, Na, S, Cl, C, O, and Zn. An increased residence time resulted in increased fine particle sizes (i.e., MMD and CMD) and decreased number concentrations. The importance of a high temperature (>850 °C) in the bed zone with intensive, air-rich, and well-mixed conditions was illustrated for wood pellets combustion with almost a total depletion of all studied PIC. The importance of the residence time was shown to be limited, and the results emphasize the need for further verification studies and technology development work.
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| 9. |
- Pettersson, Esbjörn, et al.
(författare)
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Stove performance and emission characteristics in residential wood log and pellet combustion : Part 2: Wood stove
- 2011
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 25:1, s. 315-323
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Tidskriftsartikel (refereegranskat)abstract
- The characteristics and quantities of a large number of gaseous and particulate emission components during combustion in a residential wood log stove with variations in fuel, appliance and operational conditions were determined experimentally. The measurement campaign included CO, NOx, organic gaseous carbon (OGC), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions and inorganic composition. CO varied in the range of 1100 to 7200 mg/MJfuel, while OGC varied from 210 to 3300 mg/MJfuel. Dominating VOCs were methane, followed by ethene, acetylene and benzene. Methane varied from 9 to 1600 mg/MJfuel. The non-methane volatile organic compound (NMVOC) emissions were in the range of 20-2300 mg/MJfuel. The PAHtot emissions varied from 0.8 to 220 mg/MJfuel, in most cases dominated by phenantrene, fluoranthene and pyrene. PMtot were in all cases dominated by fine particles and varied in the range 38-350 mg/MJfuel. The mass median particle diameters and the peak mobility diameters of the fine particles varied in the range 200-320 nm and 220-330 nm respectively and number concentrations in the range of 1-4×1013 particles/MJfuel. Air starved conditions, at high firing intensity, gave the highest emissions, especially for hydrocarbons. This type of conditions is seldom considered, though it may occur occasionally. The emissions from Swedish wood stoves, comparing a Swedish field study, are covered fairly well with the applied methodology, but other field studies reports considerably higher emissions especially for diluted particle sampling.
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| 10. |
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