Relation between internal boundaries and critical current in textured YBa2Cu3O7−δ: Transmission electron microscope observations

1998 ◽  
Vol 13 (10) ◽  
pp. 2800-2806 ◽  
Author(s):  
A. Khalfi ◽  
G. Trolliard ◽  
B. Soulestin ◽  
D. S. Smith ◽  
J. P. Bonnet ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Critical Current ◽  
Strong Coupling ◽  
Transmission Electron Microscope ◽  
Melting Zone ◽  
Optical Microscope ◽  
Microscope Examination ◽  
Transmission Electron ◽  
Superconducting Current ◽  
Misorientation Angles

The local critical current (Ic) at 77 K measured at the mm scale in a 60 mm long sample of YBa2Cu3O7−δ prepared by a melting zone process is correlated to the microstructure. Lower values of Ic (<20 A) were obtained in a part of the sample which optical microscope examination showed to be generally polycrystalline. In contrast, the rest of the sample, consisting mostly of large textured domains, gave values for Ic of 120 A and above. Transmission electron microscope observations revealed that the textured domains contain internal boundaries. Depending on the scale of observation, the misorientation angles across the boundaries could vary from a few tenths of a degree up to a few degrees. This seems characteristic for boundaries in textured material which allow strong coupling of the superconducting current across themselves.

Metallographic Investigation on the Effect of Cryogenic Temperature on Steel Weldments

2014 ◽  
Vol 629 ◽  
pp. 456-460 ◽  
Author(s):  
S. Rasool Mohideen ◽  
Ahmad Zaidi Ahmad Mujahid ◽  
Abdullah Shohaimi ◽  
S. Ravi
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Low Temperatures ◽  
Cryogenic Temperature ◽  
Liquid Nitrogen Temperature ◽  
Optical Microscope ◽  
Low Alloy Steel ◽  
Transmission Electron ◽  
Properties Of Materials

Materials are subjected to low temperatures either intentionally as in the case of cryogenic fuels or non-intentionally as in the case of aerospace environment and are observed to undergo changes in their properties. Microstructural changes are the premier indications of changes in the properties of materials. This paper investigates the effect of cryogenic temperature on the microstructure of low alloy steel weldments. The weldments were subjected to liquid nitrogen temperature of 77K and the microstructures were analyzed using optical microscope and transmission electron Microscope. A distinct change in the microstructure was observed which would reason out the changes in the mechanical properties of weldments.

A TRANSMISSION ELECTRON MICROSCOPE EXAMINATION OF HEMIPTERAN AND LEPIDOPTERAN GONIAL CENTROMERES

1974 ◽  
Vol 16 (2) ◽  
pp. 457-464 ◽  
Author(s):  
George Gassner ◽  
Donna J. Klemetson
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Transmission Electron Microscope ◽  
Trichoplusia Ni ◽  
Radiation Sterilization ◽  
Transmission Electron Micrograph ◽  
Electron Micrograph ◽  
Microscope Examination ◽  
Electron Microscope Examination ◽  
Transmission Electron

A transmission electron micrograph study indicates that the material identified as the centromere in gonial mitotic cells is more localized in the lepidopterans, Ephestia kuehniella (Zeller) and Trichoplusia ni (Hübner), than in the hemipteran, Oncopeutus fasciatus (Dallas). The lepidopteran centromeres are similar in size to the centromeres found in several monokinetic species. In O. fasciatus the mitotic nuclear envelope disappears while the E. kuehniella and T. ni nuclear envelopes persist during division. Factors other than the extent of the centromere material may be involved in making the Lepidoptera more resistant to radiation sterilization than the Hemiptera.

Influence of Microstructure and Precipitates on the Strength of Container Steel

2012 ◽  
Vol 586 ◽  
pp. 225-229
Author(s):  
Jia Yan Ma ◽  
Wen Liang ◽  
Rong Dong Han ◽  
Yun Guan ◽  
Zhao Jun Deng
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Transmission Electron Microscope ◽  
Optical Microscope ◽  
The Other ◽  
Precipitation Strengthening ◽  
Strengthening Effect ◽  
Transmission Electron ◽  
Uniform Dispersion ◽  
Scanning Electron

The variation rules of strength with the microstructure and precipitates of container steel were studied by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the microstructures of four kinds of test steels are all bainite and M/A island, but the number and size of islands of M/A and precipitates exist obvious difference: two kinds of test steels have fewer precipitates and more M/A islands, however, the other two kinds of steels are on the contrary. As for the former two kinds steels, the number of M/A islands is larger, and the size is smaller, the strength of steel is higher; For the later two kinds steels, the number of precipitates less than 30nm is larger, and distribution is more uniform dispersion, the strength is higher, precipitation strengthening effect is better. Getting lots of small and uniform M/A islands or precipitates is an effective way of improving the performance of steel.

Effect of Heat Treatment on the Microstructure of Cu-Cr-Zr Alloy

2017 ◽  
Vol 727 ◽  
pp. 166-170 ◽  
Author(s):  
Li Jun Peng ◽  
Hao Feng Xie ◽  
Gao Lei Xu ◽  
Guo Jie Huang ◽  
Zhen Yang
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Volume Fraction ◽  
Homogenization Temperature ◽  
Eutectic Structure ◽  
Optical Microscope ◽  
Heat Treatments ◽  
Transmission Electron ◽  
The Matrix ◽  
Zr Alloy

Effect of Heat treatments on microstructure in a Cu-0.71Cr-0.12Zr alloy (in wt.%) have been investigated. The microstructures are analyzed by optical microscope, scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope after each step of heat treatments. The results show that the as-cast microstructure of Cu-Cr-Zr alloy is Cu matrix, Cr dendrite and eutectic structure which is composed of Cu and Cu5Zr phase with a fine lamellar structure. By increasing the homogenization temperature or prolonging the holding time, the eutectic structure is dissolved into the matrix gradually and the volume fraction of the Cr phases is obviously reduced. The precipitation of Cr phase prevents from Zr-rich phases dissolving in the matrix. And the proper homogenizing process is 900°C×12 h. When the alloy aged at 450°C for 24 h, the crystallography of Cr precipitates and the orientation relationship between Cr precipitates and Cu matrix is bcc structure and KS-OR, respectively. The disk-shaped precipitate is identified as Cu5Zr phase and their habit plane is parallel to {111}Cu plane.

Anatomy and Ultrastructure of Pith Fleck-Like Tissues in Some Rosaceae Tree Species

IAWA Journal ◽  
1994 ◽  
Vol 15 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Danny Rioux
Keyword(s):  
Aqueous Solution ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Tree Species ◽  
Tissue Formation ◽  
Microscope Examination ◽  
Transmission Electron ◽  
Cambial Zone ◽  
Histochemical Tests ◽  
Anatomy And Ultrastructure

Unusual xylem tissues were found in Amelanchier laevis, Prunus pensylvanica, P. virginiana, Sorbus americana and S. aucuparia. These zones of abnormal xylem were composed of hypertrophied cells and bands that apparently comprised collapsed cells. The hypertrophied cells appeared to occupy gaps that began to form in the cambial zone. Histochemical tests indicated that the bands were highly lignified and impermeable to an aqueous solution of KMnO4, as revealed by fluorescence. Transmission electron microscope examination disclosed clearly that the bands were composed of collapsed cells and showed that the hypertrophied cells had thicker walls which contained, at times, additional layers. Although the cause of this tissue formation is unknown, its anatomy is quite similar to pith fleck tissues reported by others as being caused by cambium mining insects.

A Reproducible Selective Stain for Cardiac Sarcoplasmic Reticulum

1974 ◽  
Vol 32 ◽  
pp. 214-215
Author(s):  
R. A. Waugh ◽  
J. R. Sommer
Keyword(s):  
Complex System ◽  
Electron Microscope ◽  
Sarcoplasmic Reticulum ◽  
Transmission Electron Microscope ◽  
Electron Microscopic ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Transmission Electron

Cardiac sarcoplasmic reticulum (SR) is a complex system of intracellular tubules that, due to their small size and juxtaposition to such electron-dense structures as mitochondria and myofibrils, are often inconspicuous in conventionally prepared electron microscopic material. This study reports a method with which the SR is selectively “stained” which facilitates visualizationwith the transmission electron microscope.

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