| 1. |
- Bäcke, Olof, 1984, et al.
(author)
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Decomposition pathways in nano-lamellar CVD Ti 0.2 Al 0.8 N
- 2023
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In: Materialia. - 2589-1529. ; 30
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Journal article (peer-reviewed)abstract
- Recent progress in chemical vapour deposition (CVD) technology has enabled synthesis of metastable cubic Ti1−xAlxN coatings with x as high as 0.8–0.9. These coatings have unique micro- and nano-structures consisting of grains with epitaxially grown nanolamellae with different Al/Ti ratios, and exhibit exceptional hardness and resistance to wear and oxidation. Here, the thermal stability and decomposition of nano-lamellar CVD Ti0.2Al0.8N at temperatures between 800 and 1000 °C have been investigated using a combination of cross-sectional transmission X-ray nano-diffraction and scanning transmission electron microscopy. The decomposition started by formation of hexagonal AlN (h-AlN) in the grain boundaries throughout the coating. Below 900 °C, only limited further decomposition of the grain interiors occurred. At higher temperatures the formation of grain boundary h-AlN was followed by a bulk transformation of the nano-lamellar structure, starting at the top of the coating and subsequently sweeping inwards. The bulk transformation occurred initially through spinodal decomposition, followed by transformation of the Al-rich cubic phase to h-AlN, leading to a coarsened structure with Ti-rich domains in a h-AlN matrix. The behaviour is explained by the higher capability of grain boundaries and free surfaces to accommodate the volumetric expansion from the h-AlN formation. The results increase our understanding of the complicated decomposition processes in these metastable cubic coatings, which are of utmost importance from both technological and scientific perspectives.
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| 2. |
- Bäcke, Olof, et al.
(author)
-
Decomposition pathways in nano-lamellar CVD Ti0.2Al0.8N
- 2023
-
In: Materialia. - 2589-1529. ; 30
-
Journal article (peer-reviewed)abstract
- Recent progress in chemical vapour deposition (CVD) technology has enabled synthesis of metastable cubic Ti1−xAlxN coatings with x as high as 0.8–0.9. These coatings have unique micro- and nano-structures consisting of grains with epitaxially grown nanolamellae with different Al/Ti ratios, and exhibit exceptional hardness and resistance to wear and oxidation. Here, the thermal stability and decomposition of nano-lamellar CVD Ti0.2Al0.8N at temperatures between 800 and 1000 °C have been investigated using a combination of cross-sectional transmission X-ray nano-diffraction and scanning transmission electron microscopy. The decomposition started by formation of hexagonal AlN (h-AlN) in the grain boundaries throughout the coating. Below 900 °C, only limited further decomposition of the grain interiors occurred. At higher temperatures the formation of grain boundary h-AlN was followed by a bulk transformation of the nano-lamellar structure, starting at the top of the coating and subsequently sweeping inwards. The bulk transformation occurred initially through spinodal decomposition, followed by transformation of the Al-rich cubic phase to h-AlN, leading to a coarsened structure with Ti-rich domains in a h-AlN matrix. The behaviour is explained by the higher capability of grain boundaries and free surfaces to accommodate the volumetric expansion from the h-AlN formation. The results increase our understanding of the complicated decomposition processes in these metastable cubic coatings, which are of utmost importance from both technological and scientific perspectives.
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| 3. |
- Josefsson, Leila, et al.
(author)
-
Potato Protein Nanofibrils Produced from a Starch Industry Sidestream
- 2020
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In: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 8:2, s. 1058-1067
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Journal article (peer-reviewed)abstract
- Protein nanofibrils have emerged as promising building blocks in functional bio/nanomaterials as well as in food products. We here demonstrate that nanofibrils with amyloid-like properties can be produced from potato protein isolate, a major sidestream from the starch industry. Methods for solubilization of potato proteins are evaluated, and a protocol for the assembly of protein nanofibrils is presented. Characterization of the nanofibrils shows that they are rich in beta-sheet structure and display the cross-beta X-ray fiber diffraction pattern, which is a hallmark of amyloid-like fibrils. Atomic force microscopy shows that the fibrils are ca. 4-5 nm in diameter with a nanoscale morphology that displays a high degree of curvature. Using mass spectrometry we identify four peptides that constitute the core building blocks of the nanofibrils and show that they originate from two different classes of proteins. The structural characteristics of these peptides are distinct from previously studied plant protein nanofibrils and thereby reveal new knowledge about the formation of protein nanostructures from agricultural resources.
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| 4. |
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| 5. |
- Ornithopoulou, Eirini, et al.
(author)
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Confinement-induced self-assembly of whey protein nanofibrils into microscale fibers
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Other publication (other academic/artistic)abstract
- Protein conformation and self-assembly dictates function and structure on different hierarchical scales. We herein explore confinement-induced assembly of whey protein nanofibrils (PNF) into microscale fibers, using microfocused synchrotron X-ray scattering. The solvent evaporation forces the PNFs to align in an anisotropic fiber and the process is followed in situ by scattering experiments in a droplet placed between two anchor points. Controlling the temperature allows for variation of the evaporation rate and exploration of how the kinetics of the alignment process affect the final structure. Our findings show that there is an optimal temperature at which the order of the protein fiber has a maximum. This suggests that the degree of order results from a balance between the time scales of the forced alignment by the droplet surface and the rotational diffusion of the fibrils. Moreover, we observe that the assembly process depends on the nanoscale morphology of the PNFs. Stiff PNFs with a persistence length in the micrometer scale are aligned at the air-water interface and the anisotropy gradually decrease towards the center of the droplet. Flexible fibrils with a short persistence length (< 100 nm) align uniformly throughout the droplet, possibly due to stronger local entanglements.
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| 6. |
- Zhou, Tao, et al.
(author)
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Computational thermodynamics and kinetics-guided re-engineering of a high-performance tool steel
- 2023
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In: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 232
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Journal article (peer-reviewed)abstract
- Targeting to obtain fine dispersions of nanoscale precipitates to enhance the mechanical properties of a highperformance tool steel, re-engineering of the alloy composition and heat treatment was guided by computational thermodynamics and kinetics. A prototype alloy was prepared using the designed chemistry and heat treatment. Thereafter, advanced microstructural characterization and mechanical testing confirmed the successful design to reach a high number density of (V, Mo)C precipitates with an average diameter of about 5 nm in the peak-hardened condition, after tempering the martensite at 600 degrees C for 2 h.
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