| 1. |
- Eriksson, Gunnar, et al.
(författare)
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Combustion of wood hydrolysis residue in a 150 kW powder burner
- 2004
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 83:11-12, s. 1635-1641
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Tidskriftsartikel (refereegranskat)abstract
- A combustion test has been made with residues from hydrolysis of wood for fuel ethanol production. A 150 kW powder burner was used. Fuel feeding and combustion were stable. The average concentration of CO in the stack gas was 8 mg/MJ, the average concentration of NOx was 59 mg/MJ and the average total hydrocarbon concentration was below 1 ppm, at an average O2-concentration of 4.6%. The low contents of potassium and sodium in the hydrolysis residue make the material attractive as a gas turbine fuel and the conclusion of this test is that direct combustion may be a feasible approach for gas turbine applications.
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| 2. |
- Norell, Björn, et al.
(författare)
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Lesion characterization using spectral mammography
- 2012
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Ingår i: Medical Imaging 2012. - : SPIE - International Society for Optical Engineering.
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Konferensbidrag (refereegranskat)abstract
- We present a novel method for characterizing mammographic findings using spectral imaging without the use of contrast agent. Within a statistical framework, suspicious findings are analyzed to determine if they are likely to be benign cystic lesions or malignant tissue. To evaluate the method, we have designed a phantom where combinations of different tissue types are realized by decomposition into the material bases aluminum and polyethylene. The results indicate that the lesion size limit for reliable characterization is below 10 mm diameter, when quantum noise is the only considered source of uncertainty. Furthermore, preliminary results using clinical images are encouraging, but allow no conclusions with significance.
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| 3. |
- Svensson, Björn, et al.
(författare)
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Variable height multi-slit collimator and optimized image reconstruction in a photon-counting system for digital mammography
- 2011
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 648, s. S216-S219
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated a pre-breast collimator able to operate at variable heights for a photon-counting scanned multi-slit mammography system. A prototype system was built and used to evaluate how different collimator heights combined with optimized collimator slit widths affect dose efficiency and scan time. Moreover, new image construction software which takes into account the sub-pixel shift of each detector line was implemented and evaluated. With maintained scan time a collimator 79 mm above patient support improved dose efficiency for a 100 mu m disc by 12% and by 22% for a scan time extended by 10%. For image reconstruction and the same disc size a dose efficiency improvement of 32% +/- 9% was measured indicating a higher gain than expected. (c) 2010 Elsevier B.V. All rights reserved.
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| 4. |
- Abrahamsson, Maria, et al.
(författare)
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Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands.
- 2008
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Ingår i: Inorganic Chemistry. - : ACS. - 0020-1669 .- 1520-510X. ; 47:9, s. 3540-3548
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Tidskriftsartikel (refereegranskat)abstract
- The structural effect on the metal-to-ligand charge transfer (MLCT) excited-state lifetime has been investigated in bis-tridentate Ru(II)-polypyridyl complexes based on the terpyridine-like ligands [6-(2,2'-bipyridyl)](2-pyridyl)methane (1) and 2-[6-(2,2'-bipyridyl)]-2-(2-pyridyl)propane (2). A homoleptic ([Ru(2)(2)](2+)) and a heteroleptic complex ([Ru(ttpy)(2)](2+)) based on the new ligand 2 have been prepared and their photophysical and structural properties studied experimentally and theoretically and compared to the results for the previously reported [Ru(1)(2)](2+). The excited-state lifetime of the homoleptic Ru-II complex with the isopropylene-bridged ligand 2 was found to be 50 times shorter than that of the corresponding homoleptic Ru-II complex of ligand 1, containing a methylene bridge. A comparison of the ground-state geometries of the two homoleptic complexes shows that steric interactions involving the isopropylene bridges make the coordination to the central Ru-II ion less octahedral in [Ru(2)(2)](2+) than in [Ru(1)(2))(2+). Calculations indicate that the structural differences in these complexes influence their ligand field splittings as well as the relative stabilities of the triplet metal-to-ligand charge transfer ((MLCT)-M-3) and metal-centered ((MC)-M-3) excited states. The large difference in measured excited-state lifetimes for the two homoleptic Ru-II complexes is attributed to a strong influence of steric interactions on the ligand field strength, which in turn affects the activation barriers for thermal conversion from (MLCT)-M-3 states to short-lived (MC)-M-3 states.
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| 5. |
- Andersson, Linda, 1973, et al.
(författare)
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Rip2 modifies VEGF-induced signalling and vascular permeability in myocardial ischemia
- 2015
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 0008-6363 .- 1755-3245. ; 107:4, s. 478-486
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Tidskriftsartikel (refereegranskat)abstract
- In myocardial ischemia, vascular endothelial growth factor (VEGF) induces permeability by activating a signalling pathway that includes VEGF receptor 2 (VEGFR2), resulting in increased oedema and inflammation and thereby expanding the area of tissue damage. In this study, we investigated the role of receptor-interacting protein 2 (Rip2) in VEGF signalling and myocardial ischemia/reperfusion injury.
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| 6. |
- Andersson, Magnus, et al.
(författare)
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Vortex liquid properties in optimally doped and oxygen-deficient YBa2Cu3O7-delta single crystals
- 2000
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 332:1-4, s. 86-92
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Tidskriftsartikel (refereegranskat)abstract
- The electrical anisotropy, gamma = (m(c)/m(ab))(1/2), can easily be varied by changing the oxygen content in single crystals of YBa2Cu3O7-delta (YBCO); thus making this system useful as a test system For vortex dynamics in high-temperature superconductors (HTSC). Here, some recent results are reviewed. Measurements of the c-axis resistivity with the magnetic field B II ab-plane is shown to be a powerful tool in studying vortex velocity correlations both parallel and perpendicular to the applied field. In optimally doped crystals, we iind evidence that the in-plane vortex lattice melts at T-m into a disentangled vortex liquid, which looses its correlation along the c-axis at a higher temperature T-br > T-m. For weakly disordered crystals and magnetic fields B \\ c-axis, a relation between the vortex glass line and the magnetic field dependence of the characteristic energy, U*, in the pinned vortex liquid is proposed. This approach is shown to give support to our idea of describing the vortex glass resistivity in the liquid regime by a modified glass correlation Length, xi(g) = xi(0)\k(B)T/U-0 - 1\(-nu) which depends on the average pinning energy, Lr,, in the system [A. Rydh, O. Rapp, M. Andersson, Phys. Rev. Lett. 83 (1999) 1850].
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| 7. |
- Andersson, Magnus, et al.
(författare)
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Vortex liquid-to-solid transition in underdoped YBa2Cu3O7-delta single crystals with B parallel to ab
- 2003
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 388, s. 691-692
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Tidskriftsartikel (refereegranskat)abstract
- A nearly magnetic field independent vortex liquid-to-solid transition has been observed in both the ab-plane and in the c-axis resistivity of underdoped YBa2Cu3O7-delta single crystals for magnetic fields Bparallel toab-plane. These observations suggest that intrinsic pinning caused by the superconducting layers do neither lead to a system of completely decoupled superconducting layers nor to a smectic vortex phase at high fields. A possible explanation may include a transition driven by changes in elastic properties (e.g., the shear modulus) of the vortex system.
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| 8. |
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| 9. |
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| 10. |
- Berggren, Karl, 1989-, et al.
(författare)
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Characterization of photon-counting multislit breast tomosynthesis
- 2018
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Ingår i: Medical Physics. - : John Wiley & Sons. - 2473-4209 .- 0094-2405.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: It has been shown that breast tomosynthesis may improve sensitivity and specificity compared to two-dimensional mammography, resulting in increased detection-rate of cancers or lowered call-back rates. The purpose of this study is to characterize a spectral photon-counting multislit breast tomosynthesis system that is able to do single-scan spectral imaging with multiple collimated x-ray beams. The system differs in many aspects compared to conventional tomosynthesis using energyintegrating flat-panel detectors. Methods: The investigated system was a prototype consisting of a dual-threshold photon-counting detector with 21 collimated line detectors scanning across the compressed breast. A review of the system is done in terms of detector, acquisition geometry, and reconstruction methods. Three reconstruction methods were used, simple back-projection, filtered back-projection and an iterative algebraic reconstruction technique. The image quality was evaluated by measuring the modulation transfer-function (MTF), normalized noise-power spectrum, detective quantum-efficiency (DQE), and artifact spread-function (ASF) on reconstructed spectral tomosynthesis images for a total-energy bin (defined by a low-energy threshold calibrated to remove electronic noise) and for a high-energy bin (with a threshold calibrated to split the spectrum in roughly equal parts). Acquisition was performed using a 29 kVp W/Al x-ray spectrum at a 0.24 mGy exposure. Results: The difference in MTF between the two energy bins was negligible, that is, there was no energy dependence on resolution. The MTF dropped to 50% at 1.5 lp/mm to 2.3 lp/mm in the scan direction and 2.4 lp/mm to 3.3 lp/mm in the slit direction, depending on the reconstruction method. The full width at half maximum of the ASF was found to range from 13.8 mm to 18.0 mm for the different reconstruction methods. The zero-frequency DQE of the system was found to be 0.72. The fraction of counts in the high-energy bin was measured to be 59% of the total detected spectrum. Scantimes ranged from 4 s to 16.5 s depending on voltage and current settings. Conclusions: The characterized system generates spectral tomosynthesis images with a dual-energy photon-counting detector. Measurements show a high DQE, enabling high image quality at a low dose, which is beneficial for low-dose applications such as screening. The single-scan spectral images open up for applications such as quantitative material decomposition and contrast-enhanced tomosynthesis.
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