| 1. |
- Palmer, Nicholette D, et al.
(författare)
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A genome-wide association search for type 2 diabetes genes in African Americans.
- 2012
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Ingår i: PloS one. - San Francisco : Public Library of Science (PLoS). - 1932-6203. ; 7:1, s. e29202-
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Tidskriftsartikel (refereegranskat)abstract
- African Americans are disproportionately affected by type 2 diabetes (T2DM) yet few studies have examined T2DM using genome-wide association approaches in this ethnicity. The aim of this study was to identify genes associated with T2DM in the African American population. We performed a Genome Wide Association Study (GWAS) using the Affymetrix 6.0 array in 965 African-American cases with T2DM and end-stage renal disease (T2DM-ESRD) and 1029 population-based controls. The most significant SNPs (n = 550 independent loci) were genotyped in a replication cohort and 122 SNPs (n = 98 independent loci) were further tested through genotyping three additional validation cohorts followed by meta-analysis in all five cohorts totaling 3,132 cases and 3,317 controls. Twelve SNPs had evidence of association in the GWAS (P<0.0071), were directionally consistent in the Replication cohort and were associated with T2DM in subjects without nephropathy (P<0.05). Meta-analysis in all cases and controls revealed a single SNP reaching genome-wide significance (P<2.5×10(-8)). SNP rs7560163 (P = 7.0×10(-9), OR (95% CI) = 0.75 (0.67-0.84)) is located intergenically between RND3 and RBM43. Four additional loci (rs7542900, rs4659485, rs2722769 and rs7107217) were associated with T2DM (P<0.05) and reached more nominal levels of significance (P<2.5×10(-5)) in the overall analysis and may represent novel loci that contribute to T2DM. We have identified novel T2DM-susceptibility variants in the African-American population. Notably, T2DM risk was associated with the major allele and implies an interesting genetic architecture in this population. These results suggest that multiple loci underlie T2DM susceptibility in the African-American population and that these loci are distinct from those identified in other ethnic populations.
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| 2. |
- Tsakoumis, Nikolaos E., et al.
(författare)
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Structure-Performance Relationships on Co-Based Fischer-Tropsch Synthesis Catalysts : The More Defect-Free, the Better
- 2019
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Ingår i: ACS Catalysis. - : AMER CHEMICAL SOC. - 2155-5435 .- 2155-5435. ; 9:1, s. 511-520
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Tidskriftsartikel (refereegranskat)abstract
- Understanding and utilizing structure-performance relationships in catalytic nanomaterials is the epitome of catalysis science. Knowledge at the atomic level can potentially allow rational design of more selective and energy-efficient catalytic materials. Fischer-Tropsch synthesis on cobalt is an example of a complicated system that operates in a narrow process regime, and the nature of the reaction product is governed by numerous parameters. On an industrial model catalyst, we have simplified the structure of the active, metallic nanoparticles into a predominantly hexagonal close-packed structure via the use of a Co2C precursor. By varying the final reduction temperature, we could mildly modify catalyst microstructural properties at the nanoparticle (NP) level. Catalytic materials, although with minimal structural differences, showed significantly different performance. Evidently there is a narrow window for complete utilization of the hexagonal close-packed Co crystallites that lies between removal of lattice carbon, that remains from the Co2C precursor, and the initiation of stacking disorder, because of a transition to the face-centered cubic Co structure. Fischer-Tropsch synthesis performance indicators show that Co NPs with minimum number of crystal defects outperform catalysts with lattice defects, because of the existence of either lattice carbon or stacking faults. Therefore, catalyst preparation and activation procedures probably should be designed targeting defect-free Co crystallites.
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| 3. |
- Baur, Christian, et al.
(författare)
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Improved cycling stability in high-capacity Li-rich vanadium containing disordered rock salt oxyfluoride cathodes
- 2019
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 7:37, s. 21244-21253
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Tidskriftsartikel (refereegranskat)abstract
- Lithium-rich transition metal disordered rock salt (DRS) oxyfluorides have the potential to lessen one large bottleneck for lithium ion batteries by improving the cathode capacity. However, irreversible reactions at the electrode/electrolyte interface have so far led to fast capacity fading during electrochemical cycling. Here, we report the synthesis of two new Li-rich transition metal oxyfluorides Li2V0.5Ti0.5O2F and Li2V0.5Fe0.5O2F using the mechanochemical ball milling procedure. Both materials show substantially improved cycling stability compared to Li2VO2F. Rietveld refinements of synchrotron X-ray diffraction patterns reveal the DRS structure of the materials. Based on density functional theory (DFT) calculations, we demonstrate that substitution of V3+ with Ti3+ and Fe3+ favors disordering of the mixed metastable DRS oxyfluoride phase. Hard X-ray photoelectron spectroscopy shows that the substitution stabilizes the active material electrode particle surface and increases the reversibility of the V3+/V5+ redox couple. This work presents a strategy for stabilization of the DRS structure leading to improved electrochemical cyclability of the materials.
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| 4. |
- Sadd, Matthew, 1994, et al.
(författare)
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Visualization of Dissolution‐Precipitation Processes in Lithium–Sulfur Batteries
- 2022
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6840 .- 1614-6832. ; 12:10
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Tidskriftsartikel (refereegranskat)abstract
- In this work, light is shed on the dissolution and precipitation processes S8 and Li2S, and their role in the utilization of active material in Li-S batteries. Combining operando X-ray Tomographic Microscopy and optical image analysis, in real-time; sulfur conversion/dissolution in the cathode, the diffusion of polysulfides in the bulk electrolyte, and the redeposition of the product of the electrochemical reaction, Li2S, on the cathode are followed. Using a custom-designed capillary cell, positioning the entire cathode volume within the field of view, the conversion of elemental sulfur to soluble polysulfides during discharge is quantitatively followed. The results show the full utilization of elemental sulfur in the cathode in the initial stage of discharge, with all solid sulfur converted to soluble polysulfide species. Optical image analysis shows a rapid diffusion of polysulfides as they migrate from the cathode to the bulk electrolyte at the start of discharge and back to the cathode in the later stages of discharge, with the formation and precipitation of Li2S. The results point to the redeposition of Li2S on all available surfaces in the cathode forming a continuous insulating layer, leaving polysulfide species remaining in the electrolyte, and this is the process limiting the cell's specific capacity.
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| 5. |
- Storm, Mie Møller, et al.
(författare)
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Capillary based Li-air batteries for in situ synchrotron X-ray powder diffraction studies
- 2015
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Ingår i: Journal of Materials Chemistry A. - 2050-7488. ; 3, s. 3113-3119
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Tidskriftsartikel (refereegranskat)abstract
- For Li-air batteries to reach their full potential as energy storage system, a complete understanding of the conditions and reactions in the battery during operation is needed. To follow the reactions in situ a capillary-based Li-O2 battery has been developed for synchrotron-based in situ X-ray powder diffraction (XRPD). In this article, we present the results for the analysis of 1st and 2nd deep discharge and charge for a cathode being cycled between 2 and 4.6 V. The crystalline precipitation of Li2O2 only is observed in the capillary battery. However, there are indications of side reactions. The Li2O2 diffraction peaks grow with the same rate during charge and the development of the full width at half maximum (FWHM) is hkl dependent. The difference in the FWHM of the 100 and the 102 reflections indicate anisotropic morphology of the Li2O2 crystallites or defects along the c-axis. The effect of constant exposure of X-ray radiation to the electrolyte and cathode during charge of the battery was also investigated. X-ray exposure during charge leads to changes in the development of the intensity and the FWHM of the Li2O2 diffraction peaks. The X-ray diffraction results are supported by ex situ X-ray photoelectron spectroscopy (XPS) of discharged cathodes to illuminate non-crystalline deposited materials.
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