| 11. |
- Berg, K. E., et al.
(författare)
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Covalently linked ruthenium(II)-manganese(II) complexes : Distance dependence of quenching and electron transfer
- 2001
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Ingår i: European Journal of Inorganic Chemistry. - 1434-1948 .- 1099-1948. ; 2001:4, s. 1019-1029
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Tidskriftsartikel (refereegranskat)abstract
- Continuing our development of artificial models for photosystem II in green plants, a series of compounds have been prepared in which a RU(bpy)(3)(2+) photosensitizer is covalently Linked to a manganese(II) electron donor. In addition to a trispicolylamine Ligand, two other manganese Ligands, dipicolylamine and aminodiacetic acid, have been introduced in order to study Ligands that are appropriate for the construction of manganese dimers with open coordination sites for the binding of water. Coordination equilibria of the manganese ions were monitored by EPR. The interactions between the ruthenium and manganese moieties were probed by flash photolysis, cyclic voltammetry and steady-state and time-resolved emission measurements. The quenching of the Ru-II excited state by Mn-II was found to be rapid in complexes with short Ru-Mn distances. Nevertheless, each Run species could be photo-oxidized by bimolecular quenching with methylviologen, and the subsequent electron transfer from Mn-II to Ru-III could be monitored.
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| 12. |
- 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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| 13. |
- 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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| 14. |
- 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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| 15. |
- Blazhev, A., et al.
(författare)
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Observation of a core-excited E4 isomer in Cd-98
- 2004
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69
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Tidskriftsartikel (refereegranskat)abstract
- A core-excited I-pi=(12(+)) spin-gap isomer was identified in Cd-98 in an experiment at EUROBALL IV. It was found to feed the known I-pi=(8(+)) seniority isomer by an E4 transition. Half-lives of T-1/2=0.23 ((+4)(-3)) mus and 0.17 ((+6)(-4)) mus were measured for the two states at E-x=6635 keV and 2428 keV, respectively. From the excitation energy of the core-excited isomer a Sn-100 shell gap of 6.46(15) MeV is inferred. The measured E4 and E2 strengths, Sn-100 core excitations and the origin of empirical polarization charges are discussed in the framework of large-scale shell model calculations. An E2 polarization charge for protons of deltae(pi)
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| 16. |
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| 17. |
- Borg, Andreas, et al.
(författare)
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LIF study of mixing in a model of a vein punctured by a cannula
- 2002
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Ingår i: International Journal of Heat and Fluid Flow. - 0142-727X .- 1879-2278. ; 23:5, s. 664-670
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Tidskriftsartikel (refereegranskat)abstract
- Steady flow and mixing in a model of an "arterialized" vein punctured by a cannula as occurs during hemodialysis has been investigated in vitro. The motivation is that a major cause of vascular access dysfunction is the development of venous stenoses. This phenomenon lacks physiological explanation. However, one may attribute this quick process to the chemical content of the dialyzed blood and its flow near the point of infusion. The interest in mixing of chemical compounds in the dialyzed blood supplied through the cannula is, therefore, genuine due to the clinical impacts of haemodyalysis. We are interested in understanding the mixing of the two streams; namely, the untreated blood through the vein and the treated blood through the cannula. This mixing affects the local pH, which in turn can affect the solubility of several salts used for dialysis. In addition, since the blood contains molecules of widely different diffusivity properties, the local composition of blood near the point of injection is of interest. The hypothesis is that concentration non-uniformities may lead to undesired chemical or bio-chemical reactions leading to the pathological processes in the region around the needle. The mixing of a high Schmidt number substance in the stream entering from the cannula with the base flow in the vein is studied by laser induced fluorescence (LIF). The investigations are performed for a range of typical Reynolds numbers in the cannula and the vein found during hemodialysis. The study shows complicated mixing patterns around the cannula, and that non-uniformities in the blood persist over long distances for the lower flow rates found in vivo. For the higher flow rates, the flow loses its stability and mixing is enhanced. The nature of this instability is shown, and quantitative data of concentration fluctuations are given. We have further considered the effect of rotating the cannula. This leads to a significant change in the mixing process. The significance of the non-uniformities in mixing of solvents in the blood for the development of venous stenoses should be further studied not only in fluid dynamical terms but also in terms of endothelial (cellular) effects. (C) 2002 Published by Elsevier Science Inc.
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| 18. |
- Brantberg, Krister, et al.
(författare)
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Vestibular evoked myogenic potentials in response to skull taps for patients with vestibular neuritis
- 2003
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Ingår i: Journal of Vestibular Research-Equilibrium & Orientation. - 0957-4271 .- 1878-6464. ; 13:2-3, s. 121-130
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Tidskriftsartikel (refereegranskat)abstract
- In recent years it has been demonstrated that loud clicks generate short latency vestibular evoked myogenic potentials (VEMP). It has also been demonstrated that skull tap stimulation evokes similar VEMP. In the present study, the differences between the click-induced and the skull-tap induced VEMP were studied in 18 patients at onset of vestibular neuritis. Gentle skull taps were delivered manually above each ear on the side of the skull and on the forehead midline. The muscular responses were recorded over both sternocleidomastoid muscles using skin electrodes. Abnormal skull tap VEMP were found in the majority of the patients (10/18, 56%). However, only 4/18 (22%) showed asymmetry in the click-induced VEMP. The high percentage of abnormal skull tap VEMP might suggest that this response is not only dependent on the inferior division of the vestibular nerve, because the inferior division of this nerve is usually spared in vestibular neuritis. Moreover, the patients with abnormal skull tap VEMP differed from those with normal VEMP in their settings of the subjective visual horizontal with static head tilt in the roll plane. This might suggest that skull tap VEMP are (also) related to utricular function.
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| 19. |
- 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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| 20. |
- Britt, Östlund
(författare)
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Ageing and Technology
- 2004
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Ingår i: Science Studies. - 0786-3012. ; 17:2, s. 3-4
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Tidskriftsartikel (refereegranskat)
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