| 1. |
- Kesteloot, N., et al.
(författare)
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Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes
- 2015
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:5
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Tidskriftsartikel (refereegranskat)abstract
- Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po-196,Po-198,Po-200,Po-202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po-196,Po-198, the transitional and diagonal matrix elements of the 2(1)(+) state are determined. In Po-196,Po-198 multistep Coulomb excitation is observed, populating the 4(1)(+), 0(2)(+), and 2(2)(+) states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from Po-196 onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure.
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| 2. |
- Wallin, Anders, 1950, et al.
(författare)
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Donepezil in Alzheimer's disease : What to expect after 3 years of treatment in a routine clinical setting
- 2007
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Ingår i: Dementia and Geriatric Cognitive Disorders. - Basel : S. Karger AG. - 1420-8008 .- 1421-9824. ; 23:3, s. 150-160
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: Clinical short-term trails have shown positive effects of donepezil treatment in patients with Alzheimer's disease. The outcome of continuous long-term treatment in the routine clinical settings remains to be investigated. Methods: The Swedish Alzheimer Treatment Study (SATS) is a descriptive, prospective, longitudinal, multicentre study. Four hundred and thirty-five outpatients with the clinical diagnosis of Alzheimer's disease, received treatment with donepezil. Patients were assessed with Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog), global rating (CIBIC) and Instrumental Activities of Daily Living (IADL) at baseline and every 6 months for a total period of 3 years. Results: The mean MMSE change from baseline was positive for more than 6 months and in subgroups of patients for 12 months. After 3 years of treatment the mean change from baseline in MMSE-score was 3.8 points (95% CI, 3.0-4.7) and the ADAS-cog rise was 8.2 points (95% CI, 6.4-10.1). This is better than expected in untreated historical cohorts, and better than the ADAS-cog rise calculated by the Stern equation (15.6 points, 95% CI, 14.5-16.6). After 3 years with 38% of the patients remaining, 30% of the them were unchanged or improved in the global assessment. Conclusion: Three-year donepezil treatment showed a positive global and cognitive outcome in the routine clinical setting. Copyright © 2007 S. Karger AG.
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| 3. |
- Tjonneland, A., et al.
(författare)
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Linoleic acid, a dietary n-6 polyunsaturated fatty acid, and the aetiology of ulcerative colitis: a nested case-control study within a European prospective cohort study
- 2009
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Ingår i: Gut. - : BMJ. - 1468-3288 .- 0017-5749. ; 58:12, s. 1606-1611
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Dietary linoleic acid, an n-6 polyunsaturated fatty acid, is metabolised to arachidonic acid, a component of colonocyte membranes. Metabolites of arachidonic acid have pro-inflammatory properties and are increased in the mucosa of patients with ulcerative colitis. The aim of this investigation was to conduct the first prospective cohort study investigating if a high dietary intake of linoleic acid increases the risk of developing incident ulcerative colitis. Design and setting: Dietary data from food frequency questionnaires were available for 203 193 men and women aged 30-74 years, resident in the UK, Sweden, Denmark, Germany or Italy and participating in a prospective cohort study, the European Prospective Investigation into Cancer and Nutrition (EPIC). These participants were followed up for the diagnosis of ulcerative colitis. Each case was matched with four controls and the risk of disease calculated by quartile of intake of linoleic acid adjusted for gender, age, smoking, total energy intake and centre. Results: A total of 126 participants developed ulcerative colitis (47% women) after a median follow-up of 4.0 years (range, 1.7-11.3 years). The highest quartile of intake of linoleic acid was associated with an increased risk of ulcerative colitis (odds ratio (OR) = 2.49, 95% confidence interval (CI) = 1.23 to 5.07, p = 0.01) with a significant trend across quartiles (OR = 1.32 per quartile increase, 95% CI = 1.04 to 1.66, p = 0.02 for trend). Conclusions: The data support a role for dietary linoleic acid in the aetiology of ulcerative colitis. An estimated 30% of cases could be attributed to having dietary intakes higher than the lowest quartile of linoleic acid intake.
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| 4. |
- Fredriksson Möller, Björn, et al.
(författare)
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Azep gas turbine combined cycle power plants thermo-economic analysis
- 2005
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Ingår i: Proceedings of Ecos 2005, Vols 1-3 - Shaping our future energy systems. ; , s. 819-826
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Konferensbidrag (refereegranskat)abstract
- Conventional power plants based on fossil fuel without CO2 capture produce flue gas streams with concentrations Of CO2 between 3% and 15%, contributing to the threat of increasing global warming. Existing capture technologies such as post-combustion flue gas treatment using chemical absorption or pre-combustion carbon removal suffer from significant efficiency penalties as well as major increase in investment costs. Alternatively, combustion in O-2/CO2 atmospheres also requires expensive and energy-consuming oxygen supplies. A less energy intensive concept for oxygen production is a Mixed Conducting Membrane (MCM) reactor which produces pure oxygen from compressed air. The MCM reactor is best integrated into a conventional gas turbine combined cycle, called Advanced Zero Emissions Plant (AZEP), to provide an efficient and cost-effective power plant altogether. In this paper the economic performance of four different combined cycle alternatives in two different gas turbine sizes are evaluated; a 50 MWe size based on the Siemens SGT800 gas turbine and a 400 MWe size based on the Siemens SGT5-4000F gas turbine. ne evaluated combined cycles are one conventional combined cycle, one combined cycle with post-combustion CO2 capture and two optimised AZEP cases from a previous thermodynamic study. One AZEP alternative provides 100% CO2 capture and is thus a true zero emissions alternative, whereas the second alternative uses a sequential combustion system which enables 85% of the CO2 to be captured, making a comparison with traditional post-combustion treatment easier. The results show that the AZEP concept presents a more competitive system in terms of efficiency and economy compared to traditional capture systems.
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| 5. |
- Hart, Andrew R, et al.
(författare)
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Diet in the aetiology of ulcerative colitis: A European prospective cohort study
- 2008
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Ingår i: Digestion. - : S. Karger AG. - 1421-9867 .- 0012-2823. ; 77:1, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: The causes of ulcerative colitis are unknown, although it is plausible that dietary factors are involved. Case-control studies of diet and ulcerative colitis are subject to recall biases. The aim of this study was to examine the prospective relationship between the intake of nutrients and the development of ulcerative colitis in a cohort study. Methods: The study population was 260,686 men and women aged 20-80 years, participating in a large European prospective cohort study (EPIC). Participants were residents in the UK, Sweden, Denmark, Germany or Italy. Information on diet was supplied and the subjects were followed up for the development of ulcerative colitis. Each incident case was matched with four controls and dietary variables were divided into quartiles. Results: A total of 139 subjects with incident ulcerative colitis were identified. No dietary associations were detected, apart from a marginally significant positive association with an increasing percentage intake of energy from total polyunsaturated fatty acids (trend across quartiles OR = 1.19 (95% CI = 0.99-1.43) p = 0.07). Conclusions: No associations between ulcerative colitis and diet were detected, apart from a possible increased risk with a higher total polyunsaturated fatty acid intake. A biological mechanism exists in that polyunsaturated fatty acids are metabolised to pro-inflammatory mediators.
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| 6. |
- Sjodin, M., et al.
(författare)
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Proton-coupled electron transfer from tyrosine in a tyrosine-ruthenium-tris-bipyridine complex : Comparison with Tyrosine(z) oxidation in photosystem II
- 2000
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 122:16, s. 3932-3936
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Tidskriftsartikel (refereegranskat)abstract
- The pH- and the temperature dependence of the rate constant for electron transfer from tyrosine to ruthenium in Ru(II)(bpy)(2)(4-Me-4'CONH-L-tyrosine etyl ester-2,2'-bpy) 2PF(6) was investigated using flash photolysis. At a pH below the tyrosine pK(a) approximate to 10 the rate constant increased monotonically with pH. This increase was consistent with a concerted electron transfer/deprotonation mechanism. Also indicative of a concerted reaction was the unusually high reorganization energy, 2 eV, extracted from temperature-dependent measurements. Deprotonation of the tyrosine group, at pH > pK(a), resulted in a 100-fold increase in rate constant due to a decreased reorganization energy, lambda = 0.9 eV. Also, the rate constant became independent of pH, In Mn-depleted photosystem II a similar pH dependence has been found for electron transfer from tyrosine(Z) (Tyr(Z)) to the oxidized primary donor P680(+). On the basis of the kinetic similarities we propose that the mechanisms in the two systems are the same, that is, the electron transfer occurs as a concerted proton-coupled electron-transfer reaction, and at pH < 7 the Tyr(Z) proton is released directly to the bulk water.
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| 7. |
- Sjodin, M., et al.
(författare)
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The mechanism for proton-coupled electron transfer from tyrosine in a model complex and comparisons with Y-z oxidation in photosystem II
- 2002
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 357:1426, s. 1471-1478
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Tidskriftsartikel (refereegranskat)abstract
- In the water-oxidizing reactions of photosystem II (PSII), a tyrosine residue plays a key part as an intermediate electron-transfer reactant between the primary donor chlorophylls (the pigment P-680) and the water-oxidizing Mn cluster. The tyrosine is deprotonated upon oxidation, and the coupling between the proton reaction and electron transfer is of great mechanistic importance for the understanding of the water-oxidation mechanism. Within a programme on artificial photosynthesis, we have made and studied the proton-coupled tyrosine oxidation in a model system and been able to draw mechanistic conclusions that we use to interpret the analogous reactions in PSII.
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| 8. |
- Sjodin, M., et al.
(författare)
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Tuning proton coupled electron transfer from tyrosine : A competition between concerted and step-wise mechanisms
- 2004
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 6:20, s. 4851-4858
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Tidskriftsartikel (refereegranskat)abstract
- The intra-molecular, proton-coupled electron transfer from a tyrosine residue to covalently linked tris-bipyridine ruthenium(III) complexes in aqueous solution (Ru-III-TyrOH --> Ru-II-TyrO(.) + H+) is studied in two complexes. The Ru-III-TyrOH state is generated by laser flash-induced photo-oxidation in the presence of the electron acceptor methyl viologen. The reaction is shown to follow either a concerted electron transfer-deprotonation (CEP) mechanism or a step-wise mechanism with electron transfer followed by deprotonation (ETPT). The CEP is characterised by a pH-dependent rate constant, a large reorganisation energy (lambda = 1.4 eV at pH = 7) and a significant kinetic isotope effect: k(H)/k(D) = 1.5-3. We can explain the pH-dependence and the high lambda by the pH-dependent DeltaGdegrees' for proton release to bulk water, and by the additional reorganisation energy associated with the proton transfer coordinate (both internal and solvent), respectively. In the calculation of lambda from the temperature dependent rate constant, correction is made for the large entropy increase of the reaction (TDeltaS(rxn) approximate to0.41 eV at pH = 7 and T = 298 K). The step-wise ETPT mechanism on the other hand shows a pH-independent rate, a lower reorganisation energy and no kinetic isotope effect. We propose that our complexes can be used as models to understand proton-coupled electron transfer in radical proteins. We show that the mechanism can be switched between CEP and ETPT by tuning the reaction pH and the electrochemical potential of the Ru-III/II oxidant. With a low driving force for the overall reaction the energy conservative CEP mechanism may dominate, in spite of the higher reorganisation energy as compared to ETPT.
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