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| 2. |
- Gjestvang, D., et al.
(författare)
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Examination of how properties of a fissioning system impact isomeric yield ratios of the fragments
- 2023
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 108:6
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Tidskriftsartikel (refereegranskat)abstract
- The population of isomeric states in the prompt decay of fission fragments-so-called isomeric yield ratios (IYRs)-is known to be sensitive to the angular momentum J that the fragment emerged with, and may therefore contain valuable information on the mechanism behind the fission process. In this work, we investigate how changes in the fissioning system impact the measured IYRs of fission fragments to learn more about what parameters affect angular momentum generation. To enable this, a new technique for measuring IYRs is first demonstrated. It is based on the time of arrival of discrete gamma rays, and has the advantage that it enables the study of the IYR as a function of properties of the partner nucleus. This technique is used to extract the IYR of 134Te, strongly populated in actinide fission, from the three different fissioning systems: 232Th(n, f), 238U(n, f), at two different neutron energies, as well as 252Cf(sf). The impacts of changing the fissioning system, the compound nuclear excitation energy, the minimum J of the binary partner, and the number of neutrons emitted on the IYR of 134Te are determined. The decay code TALYS is used in combination with the fission simulation code FREYA to calculate the primary fragment angular momentum from the IYR. We find that the IYR of 134Te has a slope of 0.004 +/- 0.002 with increase in compound nucleus (CN) mass. When investigating the impact on the IYR of increased CN excitation energy, we find no change with an energy increase similar to the difference between thermal and fast fission. By varying the mass of the partner fragment emerging with 134Te, it is revealed that the IYR of 134Te is independent of the total amount of prompt neutrons emitted from the fragment pair. This indicates that neutrons carry minimal angular momentum away from the fission fragments. Comparisons with the FREYA+TALYS simulations reveal that the average angular momentum in 134Te following 238U(n, f) is 6.0 h over bar . This is not consistent with the value deduced from recent CGMF calculations. Finally, the IYR sensitivity to the angular momentum of the primary fragment is discussed. These results are not only important to help understanding the underlying mechanism in nuclear fission, but can also be used to constrain and benchmark fission models, and are relevant to the gamma -ray heating problem of reactors.
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| 3. |
- Malinowska, I, et al.
(författare)
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Hemophagocytic syndrome in children and adults
- 2014
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Ingår i: Archivum immunologiae et therapiae experimentalis. - : Springer Science and Business Media LLC. - 1661-4917 .- 0004-069X. ; 62:5, s. 385-394
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Noren, H., et al.
(författare)
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Expression of the early light-induced protein but not the PsbS protein is influenced by low temperature and depends on the developmental stage of the plant in field-grown pea cultivars
- 2003
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Ingår i: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 26:2, s. 245-253
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Tidskriftsartikel (refereegranskat)abstract
- Plant cells exposed to photo-inhibitory conditions respond by accumulation of the early light-induced proteins (Elips) with a potential photoprotective function. Here we studied the expression of Elip in various pea cultivars grown under agricultural or climate-chamber conditions. We demonstrated that the expression of Elip in all cultivars was developmentally regulated and its level decreased during flowering and post-flowering periods. Surprisingly, significant amounts of Elip transcripts, but not proteins, accumulated in senescing leaves already under low light conditions and the exposure to light stress resulted in a 10-times higher induction of Elip transcripts. Furthermore, the expression pattern of Elip transcript and protein significantly differed under field and growth-chamber conditions. First, the expression level of Elip was much higher in field-grown than in chamber-grown cultivars. Second, substantial amounts of Elip transcripts and protein were detected during the night in field-grown plants in contrast to chamber-grown cultivars due to a synergistic effect of light stress occurring during the day and low temperature present during the following night. The expression of the PsbS protein related to Elips and involved in the photoprotection of the photosystem II was relatively constant under all conditions tested.
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| 6. |
- Thuswaldner, Sophie, 1976-, et al.
(författare)
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Identification, expression, and functional analyses of a thylakoid ATP/ADP carrier from Arabidopsis
- 2007
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Ingår i: J Biol Chem. - 0021-9258 .- 1083-351X. ; 282:12, s. 8848-59
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Tidskriftsartikel (refereegranskat)abstract
- In plants the chloroplast thylakoid membrane is the site of light-dependent photosynthetic reactions coupled to ATP synthesis. The ability of the plant cell to build and alter this membrane system is essential for efficient photosynthesis. A nucleotide translocator homologous to the bovine mitochondrial ADP/ATP carrier (AAC) was previously found in spinach thylakoids. Here we have identified and characterized a thylakoid ATP/ADP carrier (TAAC) from Arabidopsis.(i) Sequence homology with the bovine AAC and the prediction of chloroplast transit peptides indicated a putative carrier encoded by the At5g01500 gene, as a TAAC. (ii) Transiently expressed TAAC-green fluorescent protein fusion construct was targeted to the chloroplast. Western blotting using a peptide-specific antibody together with immunogold electron microscopy revealed a major location of TAAC in the thylakoid membrane. Previous proteomic analyses identified this protein in chloroplast envelope preparations. (iii) Recombinant TAAC protein specifically imports ATP in exchange for ADP across the cytoplasmic membrane of Escherichia coli. Studies on isolated thylakoids from Arabidopsis confirmed these observations. (iv) The lack of TAAC in an Arabidopsis T-DNA insertion mutant caused a 30-40% reduction in the thylakoid ATP transport and metabolism. (v) TAAC is readily expressed in dark-grown Arabidopsis seedlings, and its level remains stable throughout the greening process. Its expression is highest in developing green tissues and in leaves undergoing senescence or abiotic stress. We propose that the TAAC protein supplies ATP for energy-dependent reactions during thylakoid biogenesis and turnover in plants.
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