| 1. |
- Algora, A., et al.
(författare)
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Pronounced Shape Change Induced by Quasiparticle Alignment
- 2000
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 61:3
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Tidskriftsartikel (refereegranskat)abstract
- Mean lifetimes of high-spin states of Kr-74 have been determined using the Doppler-shift attenuation method. The high-spin states were studied using the Ca-40(Ca-40, alpha 2p) reaction at a beam energy of 160 MeV with the GASP gamma-ray spectrometer. The ground-state band and negative parity side band show the presence of three different configurations in terms of transitional quadrupole deformations. A dramatic shape change was found along the ground-state band after the S-band crossing. The deduced quadrupole deformation changes are well reproduced by cranked Woods-Saxon Strutinsky calculations.
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| 2. |
- Bai, Xue-Song, et al.
(författare)
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Laminar flamelet structure at low and vanishing scalar dissipation rate
- 2000
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Ingår i: Combustion and Flame. - 0010-2180 .- 1556-2921. ; 120:3, s. 285-300
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Tidskriftsartikel (refereegranskat)abstract
- The laminar flamelet structures of methane/air, propane/air, and hydrogen/air nonpremixed combustion at low and vanishing scalar dissipation rates are investigated, by numerical calculations of a system of conservation equations in a counterflow diffusion flame configuration, together with a transport equation defining the mixture fraction and scalar dissipation rate. The chemical reaction mechanisms consist of 82 elementary reactions up to C-3 species. In the limit of vanishing scalar dissipation rate, two types of structures are shown to appear. In one structure fuel and oxygen are consumed in a thin layer located near the stoichiometric mixture fraction, Z(st), where the temperature and the major products reach their peaks. This is similar to the so-called Burke-Schumann single layer flame sheet structure. One example is the hydrogen/air diffusion flame. The second structure consists of multilayers. Fuel and oxygen are consumed at different locations. Oxygen is consumed at Z(l) (near Z(st)), where the temperature and the major products reach their peaks. Fuel is consumed at Z(r) (> Z(st)). Between Z(l) and Z(r) some intermediate and radical species are found in high concentrations. Hydrocarbon/air nonpremixed flames are of this type. It is shown that for methane/air diffusion flames, some chemical reactions which are negligible at large scalar dissipation rate near flame quenching conditions, play essential roles for the existence of the multilayer structure. Examples of such reactions are, CH4 --> CH3 + H, H2O + O-2 --> HO2 + OH, H2O + M --> H + OH + M and CHO + H-2 --> O + H. The sensitivity of the species distributions in the flamelet to the scalar dissipation rate varies for different species. The most sensitive species are the intermediates and radicals at the fuel-rich side. At low scalar dissipation rate the radiative heat transfer can significantly move the fuel consumption layer to the oxygen consumption layer, increase the oxygen leakage to fuel side, and even quench the flame. Differential diffusion modifies the species and temperature profiles in the flamelet, but does not affect the multilayer nature of the flamelet. This result is used to successfully explain the high CO emissions in a turbulent methane/air diffusion flame.
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| 3. |
- Berggren, K., et al.
(författare)
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Partitioning of peptides and recombinant protein-peptide fusions in thermoseparating aqueous two-phase systems : effect of peptide primary structure
- 2000
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Ingår i: Journal of Chromatography B. - 0378-4347. ; 743:1-2, s. 295-306
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Tidskriftsartikel (refereegranskat)abstract
- Genetic engineering has been used for fusion of peptides, with different length and composition, on a protein to study the effect on partitioning in an aqueous two-phase system. The system was composed of dextran and the thermoseparating ethylene oxide-propylene oxide random copolymer, EO30PO70. Peptides containing tryptophan, proline, arginine or aspartate residues were fused at the C-terminus of the recombinant protein ZZ-cutinase. The aim was to find effective tags for the lipolytic enzyme cutinase for large-scale extraction. The target protein and peptide tags were partitioned separately and then together in the fusion proteins in order to gain increased understanding of the influence of certain amino acid residues on the partitioning. The salt K2SO4 was used to reduce the charge dependent salt effects on partitioning and to evaluate the contribution to the partition coefficient from the hydrophobic-hydrophilic properties of the amino acid residues. The effect of Trp on peptide partitioning was independent of the difference in primary structure for (Trp)n, (Trp-Pro)n, (Ala-Trp-Trp-Pro)n and was only determined by the number of Trp. The effect of the charged residues, Arg and Asp, was dependent on the surrounding residues, i.e. if they were situated next to Trp or not. The partitioning behaviour observed for the peptides was qualitatively and in some cases also quantitatively the same as for the fusion proteins. The effect of the salts sodium perchlorate and triethylammonium phosphate on the partitioning was also studied. The salt effects observed for the peptides were qualitatively similar to the effects observed for the fusion proteins.
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| 4. |
- Berggren, K., et al.
(författare)
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Peptide fusion tags with tryptophan and charged residues for control of protein partitioning in PEG-potassium phosphate aqueous two-phase systems
- 2000
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Ingår i: Bioseparation (Dordrecht). - 0923-179X .- 1573-8272. ; 9:2, s. 69-80
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Tidskriftsartikel (refereegranskat)abstract
- A partition study with peptides and recombinant proteins in poly(ethylene glycol)4000-potassium phosphate aqueous two-phase systems has been performed. The aim was to study to what extent the insertion of charged residues could affect protein partition in addition to the already observed effects of tryptophan residues. The model proteins used are based on a staphylococcal protein A derivative, Z, and modified by the insertion of peptide tags close to the C-terminus. The tags differed with respect to their content of both Trp, negatively (Asp) and positively charged (Lys) amino acid residues. The same partitioning trends were observed for the peptides and fusion proteins. The effect of Trp residues was to direct the partitioning towards the PEG phase. The insertion of two negatively charged (Asp) residues into a Trp(4)-tag enhanced the partition towards the PEG phase even more. The introduction of positively charged (Lys) residues in addition to Trp residues, on the other hand, pulled the peptide or protein towards the potassium phosphate phase. The partitioning of peptides gave a good qualitative picture of the effect of the peptide on partitioning when fused to the protein. The efficiencies of the tags were calculated based on partitioning of tags and fusion proteins, and tag efficiencies generally varied between 60 and 85%.
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| 5. |
- Björneholm, O., et al.
(författare)
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Doppler splitting of in-flight auger decay of dissociating oxygen molecules : The localization of delocalized core holes
- 2000
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Ingår i: Physical Review Letters. - : AMERICAN PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 84:13, s. 2826-2829
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Tidskriftsartikel (refereegranskat)abstract
- By exploiting the core-excitation-induced dissociation of O-2, we find that the Auger emission exhibits a Doppler-like energy shift. We show this to be a manifestation of localization of the core hole and propose that the problem of core-hole localization versus delocalization in core-hole spectroscopies may be resolved by considering the nature of the measurement.
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| 6. |
- Braunerhjelm, Pontus, et al.
(författare)
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Does foreign direct investment replace home country investment? The effect of European integration on the location of Swedish investment
- 2000
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Ingår i: Journal of Common Market Studies. - : Wiley. - 0021-9886 .- 1468-5965. ; 38:2, s. 199-221
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this article is to examine the effects of European integration on the location of investments by Swedish multinational corporations (MNCs). Evidence is presented about the extent to which European integration has attracted investment by Swedish MNCs, and whether foreign direct investment (FDI) is being undertaken at the expense of home country investment. In the empirical analysis, involving both OLS and iterative SUR techniques, a significant difference across industries has been confirmed. A substitutionary relationship between foreign and home country investment is found for more R&D-intensive production, whereas the opposite pattern seems to prevail for production based on traditional comparative advantage. The results of this study emphasize the importance of using disaggregated industry-level data when analysing the effects of foreign direct investment on home country investment.
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| 7. |
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| 8. |
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| 9. |
- Hammarstrom, L., et al.
(författare)
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Mimicking photosystem II reactions in artificial photosynthesis : Ru(II)-polypyridine photosensitisers linked to tyrosine and manganese electron donors
- 2000
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Ingår i: Catalysis Today. - 0920-5861 .- 1873-4308. ; 58:03-feb, s. 57-69
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes a project aiming at constructing functional mimics of the oxygen evolving complex in photosystem II, coupled to photoinduced charge separation. Biomimetic electron donors, manganese complexes and tyrosine, have been linked to a Ru(II)-polypyridine photosensitiser. Oxidation of the donors by intramolecular electron transfer from the photooxidised Ru(III) complex was demonstrated using optical flash photolysis and EPR experiments. A step-wise electron transfer Mn(III,III)-->tyrosine-->Ru(III) was demonstrated, in analogy to the reaction on the donor side of photosystem II. Electron transfer from the tyrosine to Ru(III) was coupled to tyrosine deprotonation. This resulted in a large reorganisation energy and thus a slow reaction rate, unless the tyrosine was hydrogen bonded or already deprotonated. A comparison with analogous reaction in photosystem II is made. Finally, light-induced oxidation of a manganese dimer linked to a Ru(II)-photosensitiser was observed. Preliminary results suggest the possibility of photooxidising manganese dimers in several steps, which is an important step towards water oxidation,
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| 10. |
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