| 1. |
- 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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| 3. |
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| 4. |
- Adell, Martin, et al.
(författare)
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Postgrowth annealing of (Ga,Mn) As under As capping: An alternative way to increase T-C
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86, s. 112501-
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Tidskriftsartikel (refereegranskat)abstract
- In situ postgrowth annealing of (Ga,Mn)As layers under As capping is adequate for achieving high Curie temperatures (T-C) in a similar way as ex situ annealing in air or in N-2 atmosphere practiced earlier. Thus, the first efforts give an increase of T-C from 68 to 145 K after 2 h annealing at 180 degrees C. These data, in combination with lattice parameter determinations and photoemission results, show that the As capping acts as an efficient sink for diffusing Mn interstitials.
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| 5. |
- Ahmed, Istaq, 1972, et al.
(författare)
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Synthesis and structural characterization of perovskite type proton conducting BaZr1-xInxO3-delta (0.0 <= x <= 0.75)
- 2006
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738 .- 1872-7689. ; 177:17-18, s. 1395-1403
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Tidskriftsartikel (refereegranskat)abstract
- Solid state sintering has been used to prepare the cubic perovskite structured compounds BaZr1-xInxO3-delta (0.0 <= x <= 0.75). Analysis of X-ray powder diffraction (XRPD) data reveals that the unit cell parameter, a, increases linearly with an increased Indium concentration. XRPD data was also used to demonstrate the completion of sample hydration, which was reached when the materials showed a set of single-phase Bragg-peaks. Dynamic thermogravimetric analysis (TGA) data showed that approx. 89% of the total number of available oxygen vacancies can be filled in BaZr1-xInxO3-delta for x=0.50, and that the maximum water uptake occurs below 300 degrees C. Rietveld analysis of the room temperature neutron powder diffraction (NPD) data confirmed the average cubic symmetry (space group Pm-3m), and an expansion of the unit cell parameter after the hydration reaction. The strong O-H stretch band, 2500-3500 cm(-1), in the infrared absorbance spectrum clearly manifests the presence of protons in the hydrated material. Proton conductivity of hydrated BaZr1-xInxO3-delta, x=0.75 was investigated during heating and cooling cycles under dry argon atmosphere. The total conductivity during the heating cycle was nearly two orders of magnitude greater than that of cooling cycle at 300 degrees C, whilst these values were similar at higher temperatures i.e. T > 600 degrees C.
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| 6. |
- Alimadadi, Hossein, 1983, et al.
(författare)
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Corrosion properties of electrodeposited nanocrystalline and amorphous patterned Ni-W alloy
- 2009
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Ingår i: MATERIALS & DESIGN. - : Elsevier BV. - 0261-3069 .- 0264-1275 .- 1873-4197. ; 30:4, s. 1356-1361
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Tidskriftsartikel (refereegranskat)abstract
- Nickel-tungsten with satisfactory corrosion properties is a promising alloy to replace hard chromium. Relatively high adhesion between copper substrate and electrodeposited Ni-W alloy results in patterned morphology due to crack formation. In this work, corrosion resistance of patterned Ni-W alloys comprising 0-26 at.%.W were studied by potentiodynamic polarization and EIS in a medium containing Cl-. It is shown that corrosion resistance of single phase Ni-W is superior to amorphous and dual phase coated layers. It is also found that crack density is the dominant affecting factor on corrosion resistance of amorphous Ni-W alloys.
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| 7. |
- amundsen, silja, et al.
(författare)
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A comprehensive screen for SNP associations on chromosome region 5q31-33 in Swedish/Norwegian celiac disease families.
- 2007
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Ingår i: European Journal of Human genetics. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 15:9, s. 980-987
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Tidskriftsartikel (refereegranskat)abstract
- Celiac disease (CD) is a gluten-induced enteropathy, which results from the interplay between environmental and genetic factors. There is a strong human leukocyte antigen (HLA) association with the disease, and HLA-DQ alleles represent a major genetic risk factor. In addition to HLA-DQ, non-HLA genes appear to be crucial for CD development. Chromosomal region 5q31–33 has demonstrated linkage with CD in several genome-wide studies, including in our Swedish/Norwegian cohort. In a European meta-analysis 5q31–33 was the only region that reached a genome-wide level of significance except for the HLA region. To identify the genetic variant(s) responsible for this linkage signal, we performed a comprehensive single nucleotide polymorphism (SNP) association screen in 97 Swedish/Norwegian multiplex families who demonstrate linkage to the region. We selected tag SNPs from a 16 Mb region representing the 95% confidence interval of the linkage peak. A total of 1404 SNPs were used for the association analysis. We identified several regions with SNPs demonstrating moderate single- or multipoint associations. However, the isolated association signals appeared insufficient to account for the linkage signal seen in our cohort. Collective effects of multiple risk genes within the region, incomplete genetic coverage or effects related to copy number variation are possible explanations for our findings.
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| 8. |
- Andersson, J., et al.
(författare)
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Echogenecity of the carotid intima-media complex is related to cardiovascular risk factors, dyslipidemia, oxidative stress and inflammation The Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study
- 2009
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Ingår i: Atherosclerosis. - : Elsevier BV. - 1879-1484 .- 0021-9150. ; 204:2, s. 612-618
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Tidskriftsartikel (refereegranskat)abstract
- Background: Increased carotid artery intima-media thickness (IMT), measured by ultrasound, is related to an increased risk of cardiovascular disease. Since presence of echolucent plaques increases the risk further, we investigated if echogenecity of the carotid intima-media complex is related to markers of cardiovascular risk. Our aim was therefore to investigate if intima-media echogenecity is related to cardiovascular risk factors, or to markers of inflammation and oxidation in an exploratory investigation. Methods: The PIVUS cohort study is an observational study of 1016 (509 women and 507 men) randomly chosen individuals aged 70 living in Uppsala, Sweden. Carotid artery ultrasound measurements were performed. IMT and the grey scale median (GSM) value were calculated in the intima-media complex (IM-GSM) in the far wall of the common carotid artery. Traditional risk factors were evaluated together with indices of oxidative stress and inflammation. Results: In the multiple regression analysis, HDL-cholesterol, body mass index, conjugated diens, glutathione, e-selectin and TNF alfa were significantly related to IM-GSM. IMT was independently related to blood pressure, smoking and body mass index. Conclusion: The echolucency of the carotid intima-media was related to several cardiovascular risk factors not related to IMT, such as dyslipidemia, oxidative stress and inflammation. Since the echogenecity of the carotid intima-media complex was related to different risk factors compared to carotid IMT, it is worthwhile to further explore the usefulness of this new marker of the vascular wall. (C) 2009 Published by Elsevier Ireland Ltd.
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| 9. |
- Andersson, Magnus, et al.
(författare)
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A proposed time-resolved X-ray scattering approach to track local and global conformational changes in membrane transport proteins
- 2008
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 16:1, s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- Time-resolved X-ray scattering has emerged as a powerful technique for studying the rapid structural dynamics of small molecules in solution. Membrane-protein-catalyzed transport processes frequently couple large-scale conformational changes of the transporter with local structural changes perturbing the uptake and release of the transported substrate. Using light-driven halide ion transport catalyzed by halorhodopsin as a model system, we combine molecular dynamics simulations with X-ray scattering calculations to demonstrate how small-molecule time-resolved X-ray scattering can be extended to the study of membrane transport processes. In particular, by introducing strongly scattering atoms to label specific positions within the protein and substrate, the technique of time-resolved wide-angle X-ray scattering can reveal both local and global conformational changes. This approach simultaneously enables the direct visualization of global rearrangements and substrate movement, crucial concepts that underpin the alternating access paradigm for membrane transport proteins.
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| 10. |
- Andersson, Magnus, et al.
(författare)
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Structural Dynamics of Light-Driven Proton Pumps
- 2009
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 17:9, s. 1265-1275
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Tidskriftsartikel (refereegranskat)abstract
- Bacteriorhodopsin and proteorhodopsin are simple heptahelical proton pumps containing a retinal chromophore covalently bound to helix G via a protonated Schiff base. Following the absorption of a photon, all-trans retinal is isomerized to a 13-cis conformation, initiating a sequence of conformational changes driving vectorial proton transport. In this study we apply time-resolved wide-angle X-ray scattering to visualize in real time the helical motions associated with proton pumping by bacteriorhodopsin and proteorhodopsin. Our results establish that three conformational states are required to describe their photocycles. Significant motions of the cytoplasmic half of helix F and the extracellular half of helix C are observed prior to the primary proton transfer event, which increase in amplitude following proton transfer. These results both simplify the structural description to emerge from intermediate trapping studies of bacteriorhodopsin and reveal shared dynamical principles for proton pumping.
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