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- Manzoni, A. M., et al.
(författare)
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Evolution of γ/γ' phases, their misfit and volume fractions in Al 10 Co 25 Cr 8 Fe 15 Ni 36 Ti 6 compositionally complex alloy
- 2019
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Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803. ; 154, s. 363-376
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Tidskriftsartikel (refereegranskat)abstract
- Recently introduced Al10Co25Cr8Fe15Ni36Ti6 compositionally complex alloy has been investigated in the as-cast state and after heat treatment in a thorough characterization. The combination of optical, scanning and transmission electron microscopy, three dimensional atom probe and x-ray diffraction, both at lab and synchrotron level provides precise information of the microstructural evolution. After the typical dendritic solidification the alloy reveals dendritic cores consisting of γ and γ' phases and interdendritic regions consisting of η and Heusler type phases. Homogenization removes the interdendritic regions and their phases and subsequent annealing produces a microstructure similar to Ni based superalloys consisting of γ/γ' phases. In addition, about 50 μm sized Al-Ni rich needle-shaped precipitates of Heusler type structure can be observed. The four phases and their evolution with heat treatment are investigated in detail. Special focus lies on the γ/γ' misfit determination and the determination of volume fractions by different methods.
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- Rasmussen, Jay, et al.
(författare)
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Amyloid polymorphisms constitute distinct clouds of conformational variants in different etiological subtypes of Alzheimers disease
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 114:49, s. 13018-13023
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Tidskriftsartikel (refereegranskat)abstract
- The molecular architecture of amyloids formed in vivo can be interrogated using luminescent conjugated oligothiophenes (LCOs), a unique class of amyloid dyes. When bound to amyloid, LCOs yield fluorescence emission spectra that reflect the 3D structure of the protein aggregates. Given that synthetic amyloid-beta peptide (A beta) has been shown to adopt distinct structural conformations with different biological activities, we asked whether A beta can assume structurally and functionally distinct conformations within the brain. To this end, we analyzed the LCO-stained cores of beta-amyloid plaques in postmortem tissue sections from frontal, temporal, and occipital neocortices in 40 cases of familial Alzheimers disease (AD) or sporadic (idiopathic) AD (sAD). The spectral attributes of LCO-bound plaques varied markedly in the brain, but the mean spectral properties of the amyloid cores were generally similar in all three cortical regions of individual patients. Remarkably, the LCO amyloid spectra differed significantly among some of the familial and sAD subtypes, and between typical patients with sAD and those with posterior cortical atrophy AD. Neither the amount of A beta nor its protease resistance correlated with LCO spectral properties. LCO spectral amyloid phenotypes could be partially conveyed to A beta plaques induced by experimental transmission in a mouse model. These findings indicate that polymorphic A beta-amyloid deposits within the brain cluster as clouds of conformational variants in different AD cases. Heterogeneity in the molecular architecture of pathogenic A beta among individuals and in etiologically distinct subtypes of AD justifies further studies to assess putative links between A beta conformation and clinical phenotype.
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