| 1. |
- Weng, J., et al.
(author)
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Functional consequences of mutations in the MODY4 gene (IPF1) and coexistence with MODY3 mutations
- 2001
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In: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 44:2, s. 249-258
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Journal article (peer-reviewed)abstract
- Aims/hypothesis. The aim of this study was to examine the putative role of mutations in the insulin promoter 1 (IPF1) gene in early-onset diabetes. Methods. We carried out mutation screening of the IPF1 gene in 115 Scandinavian families with at least two members with onset of diabetes younger than 40 years. The allele frequencies were also tested in 183 unrelated patients with late-onset Type II (noninsulin-dependent) diabetes mellitus and in 92 nondiabetic control subjects. Results. Two novel IPF1 variants (G212R and P239Q) and one previously reported (D76N) IPF1 variant were identified in the 115 families (3.5%). The D76N variant was found in one MODY3 family (S315fsinsA of HNF1 alpha) and also in two families with late-onset Type II diabetes. The P239Q variant was identified in two families with early-onset diabetes including one with MODY3 (R272C of HNF1 alpha) and in three families with late-onset Type II diabetes. Despite the fact that the variants did not segregate completely with diabetes, the non-diabetic carriers of the IPF1 variants had increased blood glucose concentrations (p < 0.05) and reduced insulin:glucose ratios (p < 0.05) during an oral glucose tolerance test compared with non-diabetic family members without these variants. In addition, when the G212R and P239Q variants were expressed in cells without IPF1 i.e.. Nes2y cells, both variants showed about a 50% reduction in their ability to activate insulin gene transcription compared to wild-type IPF1, as measured by reporter gene assay. Conclusion/interpretation. Although mutations in the IPF-1 gene are rare in early- (3.5%) and late-onset (2.7%) Type II diabetes, they are functionally important and occur also in families with other MODY mutations.
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| 2. |
- Adebahr, Josefina, 1973, et al.
(author)
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Ab initio calculations, Raman and NMR investigation of the plastic crystal di-methyl pyrrolidinium iodide
- 2003
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In: Electrochimica Acta. - 0013-4686. ; 48:14-16, s. 2283-2289
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Journal article (peer-reviewed)abstract
- Above 110 °C the symmetric di-methyl-pyrrolidinium iodide salt forms a plastic crystal phase of interest in the area of new electrolyte materials. In this study ab initio calculations of this material has been conducted in order to assign the vibrational spectra. Raman spectroscopy measurements on the solid salt as well as on the salt dissolved in different solvents has been performed and these have been compared to the theoretical spectra. Furthermore, Raman spectra as a function of temperature have been recorded to investigate possible changes in inter-ionic interaction and/or structure through the phase transition. 1 H NMR linewidth measurements as a function of temperature showed a large decrease in linewidth above 100 °C, attributed here to an increase in mobility in agreement with a previously reported phase transition at ∼ 110 °C. © 2003 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Adebahr, Josefina, 1973, et al.
(author)
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Ion transport in polymer electrolytes containing nanoparticulate TiO2: The influence of polymer morphology
- 2003
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In: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 5:4, s. 720-725
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Journal article (peer-reviewed)abstract
- Recent studies have shown that composite polymer electrolytes, formed by dispersing nanosized ceramic particles in polyether-based electrolytes, have improved ion transport properties as compared to their unfilled analogues. In the present study polymer electrolytes with different loadings of nano-sized ceramic particles (TiO 2 ) and different polymer chemistry and morphology have been investigated. Of special interest are filler induced effects on polymer, solvent and cationic mobility. Partly crystalline polymer electrolytes based on poly(ethylene oxide) have been compared to fully amorphous polymer electrolytes based on a polyether urethane, as well as gel electrolytes based on PMMA. 7 Li pfg-NMR, linewidth and spin-spin relaxation times as well as 1 H pfg-NMR and spin-spin relaxation times, were measured as a function of temperature and composition. The 1 H spin-spin relaxation measurements reveal increased average polymer mobility with the addition of filler up to a maximum at 4 and 8 wt.% TiO 2 for the fully amorphous and the partly crystalline electrolytes, respectively. The 7 Li linewidth measurements for the fully amorphous system show a broadening of the linewidth with addition of filler. Based on variable temperature measurements this broadening is interpreted as a result of the inhomogeneity introduced by the filler particles. Pulsed field gradient (pfg) diffusion measurements were employed to determine ion and solvent self-diffusion coefficients. In the case of the PMMA-based gel electrolyte and the fully amorphous electrolytes enhanced cation self-diffusion was observed upon addition of TiO 2 .
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| 4. |
- Adebahr, Josefina, et al.
(author)
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Li-7 NMR measurements of polymer gel electrolytes
- 2002
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In: Solid State Ionics. - 0167-2738. ; 147:3-4, s. 303-307
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Journal article (peer-reviewed)abstract
- Ion conducting polymer gels prepared from (ethylene oxide)(n) grafted methacrylates, ethylene carbonate (EC), gamma butyrolactone (gBL), and lithium hexafluorophosphate are studied by means of nuclear magnetic resonance spectroscopy, This study shows that there are at least two possible lithium sites with different mobility. The lithium-ions with lower mobility dominate at room temperature, but this is changed as the temperature is increased. The NMR results also show that the Li-7 spin-spin relaxation time decreases with increasing length of the grafted ethylene oxide side chains, indicating a stronger interaction between the polymer and the Li-ions, and hence, a lower mobility of the Li-ions. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 5. |
- Adebahr, Josefina, 1973, et al.
(author)
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Lithium coordination and mobility in gel electrolytes based on an acrylate polymer with ethylene oxide side chains
- 2003
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In: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 1364-5501 .- 0959-9428. ; 13:4, s. 814-817
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Journal article (peer-reviewed)abstract
- Multinuclear NMR has been used to investigate the structure and mobility of a series of polymer gel electrolytes. The co-polymers used as matrixes in the gels have acrylate backbones and side chains of ethylene oxide, where the length of the side chains has been varied, while the ratio of acrylate to ethylene oxide has been kept constant. The electrolyte is a mixture of lithium perchlorate and two solvents, ethylene carbonate and gamma butyrolactone. 13 C spectra of the different gel electrolytes shows that both solvents interact with the salt, and that the strength of the interaction increases with decreasing length of the polymer side chains. It also appears that the lithium ions show no selectivity between the two types of solvent. Furthermore, the lithium chemical shift moves progressively upfield with increasing length of the side chains, showing a gradual change in interaction from lithium-solvent to lithium-(ethylene oxide).
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| 6. |
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| 7. |
- Every, HA, et al.
(author)
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Transport properties in a family of dialkylimidazolium ionic liquids
- 2004
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In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. - 1463-9076. ; 6:8, s. 1758-65
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Journal article (peer-reviewed)abstract
- The transport properties of 1,3-methylalkylimidazolium based ionic liquids are sensitive to their chemical structure. In this work, two key features of the chemical structure were investigated: the role of the anion and the length of the alkyl chain. Four different anions were examined for the 1,3-methylethylimidazolium salt (MeEtlmX): bromide (Br-), iodide (I-), trifluoromethanesulfonate (Tf-) and bis(trifluoromethanesulfonyt)-amide (NTf2-) anions. Increasing the size of the anion resulted in a decrease of the melting point and a slight increase in the cation diffusion coefficient. The differences in cation diffusion behaviour reflect the differences in viscosity, with much higher viscosities expected for the halide salts. In contrast to this diffusion behaviour, the melt conductivities are all very similar. The inconsistency between the calculated conductivity (based on diffusion measurements) and the conductivity measured, however, is attributed to correlated ion motions and/or the diffusion of neutral species that do not contribute to the conductivity. The effect of the length of the alkyl substituent was also studied for 1,3-methylalkylimidazolium iodide (MeRImI). Increasing the length of the alkyl chain, from methyl to a linear heptyl chain, suppresses the melting point and decreases both the conductivity and cation diffusion coefficients. In this case, the viscosity, as well as the size of the cation, influence ion transport in these materials.
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