| 921. |
- Tiukova, Ievgeniia, 1987, et al.
(författare)
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Identification and characterisation of two high-affinity glucose transporters from the spoilage yeast Brettanomyces bruxellensis
- 2019
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Ingår i: FEMS microbiology letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 366:17
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Tidskriftsartikel (refereegranskat)abstract
- The yeast Brettanomyces bruxellensis (syn. Dekkera bruxellensis) is an emerging and undesirable contaminant in industrial low-sugar ethanol fermentations that employ the yeast Saccharomyces cerevisiae. High-affinity glucose import in B. bruxellensis has been proposed to be the mechanism by which this yeast can outcompete S. cerevisiae. The present study describes the characterization of two B. bruxellensis genes (BHT1 and BHT3) believed to encode putative high-affinity glucose transporters. In vitro-generated transcripts of both genes as well as the S. cerevisiae HXT7 high-affinity glucose transporter were injected into Xenopus laevis oocytes and subsequent glucose uptake rates were assayed using 14C-labelled glucose. At 0.1 mM glucose, Bht1p was shown to transport glucose five times faster than Hxt7p. pH affected the rate of glucose transport by Bht1p and Bht3p, indicating an active glucose transport mechanism that involves proton symport. These results suggest a possible role for BHT1 and BHT3 in the competitive ability of B. bruxellensis.
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| 922. |
- Tiukova, Ievgeniia, 1987, et al.
(författare)
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Proteome analysis of xylose metabolism in Rhodotorula toruloides during lipid production
- 2019
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834 .- 1754-6834. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Rhodotorula toruloides is a promising platform organism for production of lipids from lignocellulosic substrates. Little is known about the metabolic aspects of lipid production from the lignocellolosic sugar xylose by oleaginous yeasts in general and R. toruloides in particular. This study presents the first proteome analysis of the metabolism of R. toruloides during conversion of xylose to lipids. Results: Rhodotorula toruloides cultivated on either glucose or xylose was subjected to comparative analysis of its growth dynamics, lipid composition, fatty acid profiles and proteome. The maximum growth and sugar uptake rate of glucose-grown R. toruloides cells were almost twice that of xylose-grown cells. Cultivation on xylose medium resulted in a lower final biomass yield although final cellular lipid content was similar between glucose- and xylose-grown cells. Analysis of lipid classes revealed the presence of monoacylglycerol in the early exponential growth phase as well as a high proportion of free fatty acids. Carbon source-specific changes in lipid profiles were only observed at early exponential growth phase, where C18 fatty acids were more saturated in xylose-grown cells. Proteins involved in sugar transport, initial steps of xylose assimilation and NADPH regeneration were among the proteins whose levels increased the most in xylose-grown cells across all time points. The levels of enzymes involved in the mevalonate pathway, phospholipid biosynthesis and amino acids biosynthesis differed in response to carbon source. In addition, xylose-grown cells contained higher levels of enzymes involved in peroxisomal beta-oxidation and oxidative stress response compared to cells cultivated on glucose. Conclusions: The results obtained in the present study suggest that sugar import is the limiting step during xylose conversion by R. toruloides into lipids. NADPH appeared to be regenerated primarily through pentose phosphate pathway although it may also involve malic enzyme as well as alcohol and aldehyde dehydrogenases. Increases in enzyme levels of both fatty acid biosynthesis and beta-oxidation in xylose-grown cells was predicted to result in a futile cycle. The results presented here are valuable for the development of lipid production processes employing R. toruloides on xylose-containing substrates.
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| 923. |
- Tolbod, Lars P., et al.
(författare)
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Non-invasive quantification of tumor blood flow in prostate cancer using O-15-H2O PET/CT
- 2018
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Ingår i: American Journal of Nuclear Medicine and Molecular Imaging. - : E-CENTURY PUBLISHING CORP. - 2160-8407. ; 8:5, s. 292-302
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Tidskriftsartikel (refereegranskat)abstract
- Tumor blood flow (TBF) measurements in prostate cancer (PCa) provide an integrative index of tumor growth, which could be important for primary diagnosis and therapy response evaluation. O-15-water PET is the noninvasive gold standard but is technically demanding. The aim of this study was to compare the accuracy of three different non-invasive strategies with an invasively measured arterial input function (BSIF): Using image-derived input functions (IDIF) from either 1) a separate heart scan or 2) the pelvic scan or 3) a populations-based input function (PBIF). Nine patients with biopsy-verified PCa scheduled for prostatectomy were included. All patients were characterized with serum levels of PSA (s-PSA), multiparametric magnetic resonance imaging (mpMRl) and post-surgical histopathology Gleason Grade. Dynamic O-15-water was performed of the heart and the pelvic area 15 minutes apart. TBF estimated from both wash-in (K-1) and wash-out (k(2)) constants was calculated using a one-compartmental model. Results: Mean (range) s PSA was 12 (3-27) ng/mL, Gleason Grade Group was 2.9 (1-5), k(2) was 0.44 (0.007-1.2), and K-1 was 0.24 (0.07-0.55) mL,/mL/min. k(2) (BSIF)correlated with s-PSA (r=0.86, P<0.01) and Gleason Grade Group (rho=0.78, P=0.01). BSIF, heart-IDIF and PBIF provided near-identical k(2) and K-1 (r>0.95, P<0.001) with slopes near unity. The correlations of BSIF and pelvic-IDIF rate constants were good (r>0.95, P<0.001), but individual errors high. In conclusion, non-invasive protocols for O-15-water PET with IDIF or PBIF accurately measures perfusion in prostate cancer and might be useful for evaluation of tumor aggressiveness and treatment response.
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| 924. |
- Tolborg, Kasper, et al.
(författare)
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Accurate charge densities from powder X-ray diffraction - A new version of the Aarhus vacuum imaging-plate diffractometer
- 2017
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Ingår i: Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials. - 2052-5206. ; 73:4, s. 521-530
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Tidskriftsartikel (refereegranskat)abstract
- In recent years powder X-ray diffraction has proven to be a valuable alternative to single-crystal X-ray diffraction for determining electron-density distributions in high-symmetry inorganic materials, including subtle deformation in the core electron density. This was made possible by performing diffraction measurements in vacuum using high-energy X-rays at a synchrotron-radiation facility. Here we present a new version of our custom-built in-vacuum powder diffractometer with the sample-to-detector distance increased by a factor of four. In practice this is found to give a reduction in instrumental peak broadening by approximately a factor of three and a large improvement in signal-to-background ratio compared to the previous instrument. Structure factors of silicon at room temperature are extracted using a combined multipole-Rietveld procedure and compared with ab initio calculations and the results from the previous diffractometer. Despite some remaining issues regarding peak asymmetry, the new diffractometer yields structure factors of comparable accuracy to the previous diffractometer at low angles and improved accuracy at high angles. The high quality of the structure factors is further assessed by modelling of core electron deformation with results in good agreement with previous investigations.The present state of X-ray electron-density determination from powder-diffraction data is briefly reviewed together with the first results from a new large-diameter in-vacuum diffractometer.
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| 925. |
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| 926. |
- Torsheim, Torbjørn, et al.
(författare)
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Social inequalities in self-rated health : A comparative cross-national study among 32,560 Nordic adolescents
- 2018
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Ingår i: Scandinavian Journal of Public Health. - London : Sage Publications. - 1403-4948 .- 1651-1905. ; 46:1, s. 150-156
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: We aimed to estimate the magnitude of socioeconomic inequality in self-rated health among Nordic adolescents (aged 11, 13 and 15 years) using the Family Affluence Scale (a composite measure of material assets) and perceived family wealth as indicators of socioeconomic status.METHODS: Data were collected from the Health Behaviour in School-aged Children (HBSC) survey in 2013-2014. A sample of 32,560 adolescents from Denmark, Norway, Finland, Iceland, Greenland and Sweden was included in the study. Age-adjusted regression analyses were used to estimate associations between fair or poor self-rated health and the ridit scores for family affluence and perceived wealth.RESULTS: The pooled relative index of inequality of 2.10 indicates that the risk of fair or poor health was about twice as high for young people with the lowest family affluence relative to those with the highest family affluence. The relative index of inequality for observed family affluence was highest in Denmark and lowest in Norway. For perceived family wealth, the pooled relative index of inequality of 3.99 indicates that the risk of fair or poor health was about four times as high for young people with the lowest perceived family wealth relative to those with the highest perceived family wealth. The relative index of inequality for perceived family wealth was highest in Iceland and lowest in Greenland.CONCLUSIONS: Social inequality in self-rated health among adolescents was found to be robust across subjective and objective indicators of family affluence in the Nordic welfare states. © Author(s) 2017
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| 927. |
- Torstensson, Peter, 1981, et al.
(författare)
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High-Frequency Vertical Wheel-Rail Contact Forces at High Vehicle Speeds-The Influence of Wheel Rotation
- 2012
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Ingår i: Notes on Numerical Fluid Mechanics and Multidisciplinary Design. - Tokyo : Springer Japan. - 1612-2909 .- 1860-0824. - 9784431539261 ; 118, s. 43-50
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Konferensbidrag (refereegranskat)abstract
- Dynamic vehicle-track interaction at high vehicle speeds is investigated in a frequency range from about 20 Hz to 3 kHz. The inclusion of wheel rotation in the vehicle model is investigated by implementing a structural dynamics model of a rotating wheelset in an existing simulation environment. Calculated wheel-rail contact forces using this comprehensive flexible wheelset model are compared with contact forces based on less detailed, non-rotating wheelset models. Load cases including broad-band wheel-rail excitation due to vertical rail irregularities (rail corrugation) and impact excitation caused by a local deviation from the nominal wheel radius (wheel flat) are considered. Viewed from the excitation point, each wheelset resonance peak of multiplicity two splits into two peaks; the separation of the two peaks increases with increasing rotational speed. If the wheelset model is excited at a frequency where two different mode shapes, due to the wheel rotation, have coinciding resonance frequencies, the contact force calculated for the rotating wheelset model differs significantly from those of the non-rotating models. Further, the use of a flexible rotating wheelset model is recommended for load cases leading to large magnitude contact force components in the high-frequency range (above 1.5 kHz). In particular, the influence of the radial wheel eigenmodes with two or three nodal diameters is significant.
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| 928. |
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| 929. |
- Torstensson, Peter, 1981, et al.
(författare)
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Hybrid model for prediction of impact noise generated at railway crossings
- 2016
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Ingår i: Proceedings of the 12h International Workshop on Railway Noise (IWRN12), Terrigal, Australia, September 12-16 (2016). ; , s. 539 - 545
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Konferensbidrag (refereegranskat)abstract
- A hybrid model for the prediction of impact noise at railway crossings is presented. The hybrid model combines the simulation of vertical wheel‒rail contact force in the time domain and the prediction of sound pressure level using a linear frequency-domain model. The time-domain model uses moving Green’s functions for the vehicle and track models (accounting for wheel flexibility and a discretely supported rail with space-variant beam properties) and a non-Hertzian wheel‒rail contact model. The time-domain and frequency-domain models are coupled based on the concept of an equivalent roughness spectrum. The model is demonstrated by investigating the influence of axle load, vehicle speed and wheel profile on generated impact noise levels. A negligible influence on impact noise is observed for axle loads in the interval 15 – 25 tonnes. On the other hand, increasing vehicle speed from 80 km/h to 150 km/h, or comparing a nominal S1002 wheel profile with a severely hollow worn profile, result in substantially higher levels of impact noise; for the given wheel and track conditions the differences are in the order of 10 dB(A).
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| 930. |
- Torstensson, Peter, 1981, et al.
(författare)
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Hybrid model for prediction of impact noise generated at railway crossings
- 2018
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Ingår i: Notes on Numerical Fluid Mechanics and Multidisciplinary Design. - Cham : Springer International Publishing. - 1612-2909 .- 1860-0824. ; 139, s. 759-769, s. 759-769
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- A hybrid model for the prediction of impact noise at railway crossings is presented. The hybrid model combines the simulation of vertical wheel‒rail contact force in the time domain and the prediction of sound pressure level using a linear frequency-domain model. The time-domain model uses moving Green’s functions for the vehicle and track models (accounting for wheel flexibility and a discretely supported rail with space-variant beam properties) and a non-Hertzian wheel‒rail contact model. The time-domain and frequency-domain models are coupled based on the concept of an equivalent roughness spectrum. The model is demonstrated by investigating the influence of axle load, vehicle speed and wheel profile on generated impact noise levels. A negligible influence on impact noise is observed for axle loads in the interval 15–25 tonnes. On the other hand, increasing vehicle speed from 80 to 150 km/h, or comparing a nominal S1002 wheel profile with a severely hollow worn profile, result in substantially higher levels of impact noise; for the given wheel and track conditions the differences are in the order of 10 dB(A).
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