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- Ciudad, S., et al.
(författare)
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A beta(1-42) tetramer and octamer structures reveal edge conductivity pores as a mechanism for membrane damage
- 2020
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Formation of amyloid-beta (A beta) oligomer pores in the membrane of neurons has been proposed to explain neurotoxicity in Alzheimers disease (AD). Here, we present the three-dimensional structure of an A beta oligomer formed in a membrane mimicking environment, namely an A beta(1-42) tetramer, which comprises a six stranded beta-sheet core. The two faces of the beta-sheet core are hydrophobic and surrounded by the membrane-mimicking environment while the edges are hydrophilic and solvent-exposed. By increasing the concentration of A beta(1-42) in the sample, A beta(1-42) octamers are also formed, made by two A beta(1-42) tetramers facing each other forming a beta-sandwich structure. Notably, A beta(1-42) tetramers and octamers inserted into lipid bilayers as well-defined pores. To establish oligomer structure-membrane activity relationships, molecular dynamics simulations were carried out. These studies revealed a mechanism of membrane disruption in which water permeation occurred through lipid-stabilized pores mediated by the hydrophilic residues located on the core beta-sheets edges of the oligomers.
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- Owoseni, Tunji A., et al.
(författare)
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Microstructure and Tribological Performance of HVAF-Sprayed Ti-6Al-4V Coatings
- 2023
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Ingår i: Coatings. - : MDPI. - 2079-6412. ; 13:11, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Ti-6Al-4V is a widely used titanium alloy in aviation and bio/chemical applications for its attractive mechanical and corrosion resistance properties. The use of Ti-6Al-4V as a coating for repair purposes through thermal spray techniques provides a unique productivity opportunity. A repair coating must be dense to provide the required in-service functionalities, such as resistance to wear. The High Velocity Air Fuel (HVAF) thermal spray technique deposits dense coatings with reduced concern for oxide inclusions. This work presents an investigation of the microstructure, dry sliding, and solid particle erosive wear performance of four different coatings engineered through the configuration of the nozzle of an HVAF spray gun, based on the length of the nozzle and the size of the nozzle exit. A long nozzle length and wide nozzle exit mean increased inflight dwell time and reduced average inflight temperature for the sprayed particles, respectively—a reversed configuration means the opposite. The tested coatings showed a porosity of less than 2%. The sliding and erosion wear performance of the densest of the coatings compares to that of the bulk material tested under the same conditions. Electron microscopy was used to investigate the driving mechanisms for the performance of the respective coatings. The implications of the results are discussed for the potential adoption of HVAF-sprayed coatings in metal component repair.
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