| 1. |
- Grotkjær, Thomas, et al.
(författare)
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Comparative metabolic network analysis of two xylose fermenting recombinant Saccharomyces cerevisiae strains
- 2005
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Ingår i: Metabolic engineering. - : Elsevier BV. - 1096-7176 .- 1096-7184. ; 7:5-6, s. 437-444
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Tidskriftsartikel (refereegranskat)abstract
- The recombinant xylose fermenting strain Saccharomyces cerevisiae TMB3001 can grow on xylose, but the xylose utilisation rate is low. One important reason for the inefficient fermentation of xylose to ethanol is believed to be the imbalance of redox co-factors. In the present study, a metabolic flux model was constructed for two recombinant S. cerevisiae strains: TMB3001 and CPB.CR4 which in addition to xylose metabolism have a modulated redox metabolism, i.e. ammonia assimilation was shifted from being NADPH to NADH dependent by deletion of gdh1 and over-expression of GDH2. The intracellular fluxes were estimated for both strains in anaerobic continuous cultivations when the growth limiting feed consisted of glucose (2.5 g L−1) and xylose (13 g L−1). The metabolic network analysis with 13C labelled glucose showed that there was a shift in the specific xylose reductase activity towards use of NADH as co-factor rather than NADPH. This shift is beneficial for solving the redox imbalance and it can therefore partly explain the 25% increase in the ethanol yield observed for CPB.CR4. Furthermore, the analysis indicated that the glyoxylate cycle was activated in CPB.CR4.
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| 2. |
- Hiensch, Martin, et al.
(författare)
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Two-material rail development : field test results regarding rolling contact fatigue and squeal behaviour
- 2005
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 258:7-8, s. 964-972
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Tidskriftsartikel (refereegranskat)abstract
- Results from the European 5th Framework project “InfraStar” are presented. The InfraStar project is developing a two-material rail to increase the productivity and reliability of rail infrastructure. The two-material rail aims to be rolling contact fatigue (RCF) resistant and to reduce squeal noise.The InfraStar consortium has built a high level of wheel–rail expertise and understanding regarding RCF initiation and development, level and position of wheel–rail contact forces, and new interface materials and has gained experience in both laboratory and field test operating conditions. Within the project a validated theoretical train–track interaction model and a fatigue design model for two-material rails have been developed.This paper focuses on the field test results of the two-material rail, and how the predictions and expectations from the selection process match with the results observed in track. Results are very promising. The two-material rail prototypes, now over 1 year in track, show no RCF damage where the non-treated rail shows clear RCF damage. The development of the application process and other objectives of the InfraStar project are discussed.
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| 5. |
- Matzka, Jürgen, et al.
(författare)
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A new aeromagnetic survey of the North Pole and the Arctic Ocean north of Greenland and Ellesmere Island
- 2010
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Ingår i: Earth Planets and Space. - : Society of Geomagnetism and Earth, Planetary and Space Sciences. - 1343-8832 .- 1880-5981. ; 62:10, s. 829-832
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Tidskriftsartikel (refereegranskat)abstract
- We present a preliminary analysis of more than 50,000 km of aeromagnetic survey lines flown in the Arctic Ocean, acquired in 2009 with an optically pumped scalar magnetometer as part of the airborne geophysical survey 'LOMGRAV'. From the observations we removed main and magnetospheric fields as given by the CHAOS-3 field model (Olsen et al., 2010) and remaining external fields as monitored by the Canadian magnetic observatory Alert. The reduced data were levelled based on cross-over differences at line intersections. Finally, a grid was computed, upward continued by 3500 m and compared with the EMAG2 grid (Maus et al., 2009), showing a good general agreement but also areas with systematic differences. The obtained data are expected to be part of the next version of the World Digital Magnetic Anomaly Map (WDMAM).
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| 6. |
- Panagiotou, Gianni, et al.
(författare)
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Intracellular metabolite profiling of Fusarium oxysporum converting glucose to ethanol
- 2005
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 115:4, s. 425-434
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Tidskriftsartikel (refereegranskat)abstract
- The filamentous fungus Fusarium oxysporum is known for its ability to produce ethanol by simultaneous saccharification and fermentation (SSF) of cellulose. However, the conversion rate is low and significant amounts of acetic acid are produced as a by-product. In this study, the growth characteristics of F. oxysporum were evaluated in a minimal medium using glucose as the sole carbon source in aerobic, anaerobic and oxygen-limited batch cultivations. Under aerobic conditions the maximum specific growth rate was found to be 0.043 h−1, and the highest ethanol yield (1.66 mol/mol) was found under anaerobic conditions. During the different phases of the cultivations, the intracellular profiles were determined under aerobic and anaerobic conditions. The profiles of the phosphorylated intermediates indicated that there was a high glycolytic flux at anaerobic growth conditions, characterized by high efflux of glyceraldehyde-3-phosphate (G3P) and fructose-6-phosphate (F6P) from the pentose phosphate pathway (PPP) to the Embden–Meyerhof–Parnas (EMP) pathway, resulting in the highest ethanol production under these conditions. The amino acid profile clearly suggests that the TCA cycle was primarily active under aerobic cultivation. On the other hand, the presence of high levels of γ-amino-n-butyric acid (GABA) under anaerobic conditions suggests a functional GABA bypass and a possible block in the TCA cycle at these conditions.
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| 7. |
- Paulsson, Björn, 1946-, et al.
(författare)
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Upgrading of infrastructure in order to meet new operation and market demands
- 2017
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Rapport (refereegranskat)abstract
- The European objective of a modal shift of freight transports to railways will require extensive upgrading of existing railway lines since very few dedicated freight railways are currently being built and existing lines were built for traffic demands at the time of construction. A transition to increased and enhanced railway freight operations can therefore be costly and complicated. To minimize negative effects, a guideline for upgrading was developed within the Capacity4Rail project. This handbook presents the major findings. In particular it outlines different upgrading possibilities and their implications, and details structured approaches to upgrading analyses. It discusses possibilities for upgrading of substructures, bridges, tunnels, and the track structure. In these areas, an overview of challenges and possibilities is presented together with examples of experience from operational upgrading. It concludes that freight line upgrading using a more streamlined approach as outlined in the guideline is a necessity if EU objectives on modal shifts in transportation are to be met. Further, it demonstrates why a political drive is necessary to increase efforts to upgrade freight lines.
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