Three-dimensional imaging and characterization of the oxide scale formed on a polycrystalline nickel-based superalloy

2019 ◽  
Vol 167 ◽  
pp. 16-20 ◽  
Author(s):  
Sebastian Lech ◽  
Adam Kruk ◽  
Aleksander Gil ◽  
Grzegorz Cempura ◽  
Alina Agüero ◽  
...  
Radiology ◽  
1995 ◽  
Vol 196 (1) ◽  
pp. 135-142 ◽  
Author(s):  
T L Chenevert ◽  
M A Helvie ◽  
A M Aisen ◽  
I R Francis ◽  
D D Adler ◽  
...  

2020 ◽  
Vol 169 ◽  
pp. 108634
Author(s):  
Adam Kruk ◽  
Sebastian Lech ◽  
Aleksander Gil ◽  
Grzegorz Cempura ◽  
Alina Agüero ◽  
...  

Author(s):  
J. J. Laidler

The presence of three-dimensional voids in quenched metals has long been suspected, and voids have indeed been observed directly in a number of metals. These include aluminum, platinum, and copper, silver and gold. Attempts at the production of observable quenched-in defects in nickel have been generally unsuccessful, so the present work was initiated in order to establish the conditions under which such defects may be formed.Electron beam zone-melted polycrystalline nickel foils, 99.997% pure, were quenched from 1420°C in an evacuated chamber into a bath containing a silicone diffusion pump fluid . The pressure in the chamber at the quenching temperature was less than 10-5 Torr . With an oil quench such as this, the cooling rate is approximately 5,000°C/second above 400°C; below 400°C, the cooling curve has a long tail. Therefore, the quenched specimens are aged in place for several seconds at a temperature which continuously approaches the ambient temperature of the system.


Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.


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