scholarly journals Transmission electron microscopy of simulated DWPF high level nuclear waste glasses following gamma irradiation

1994 ◽  
Author(s):  
J.C. Marra ◽  
N.E. Bibler ◽  
J.R. Harbour ◽  
M.H. Tosten
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gamma Irradiation ◽  
Nuclear Waste ◽  
Transmission Electron ◽  
High Level Nuclear Waste ◽  
High Level

Characterization of cellular development and fatty acid accumulation in thraustochytrid Aurantiochytrium strains of Taiwan

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Natarajan Velmurugan ◽  
Yesupatham Sathishkumar ◽  
Shashanka Sonowal ◽  
Ka-Lai Pang ◽  
Yang Soo Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Flow Cytometry ◽  
Cell Growth ◽  
Intracellular Lipid ◽  
Fatty Acid Accumulation ◽  
Transmission Electron ◽  
Intracellular Lipid Accumulation ◽  
High Level

Abstract Long-chain saturated and polyunsaturated fatty acids of two new thraustochytrid isolates cultured from Taiwan mangroves, Aurantiochytrium sp. IMB169 and Aurantiochytrium sp. IMB171, were characterized through their cell growth and development in relation to their intracellular lipid accumulation using transmission electron microscopy. Flow cytometry in combination with the lipophilic fluorescent dye BODIPY 505/515 was used to stain and characterize intracellular lipid bodies in the two isolates. The transmission electron microscopy and flow cytometry analyses revealed a progressive accumulation of lipid products in IMB169 and IMB171. Further, selective BODIPY stained cells were successfully separated and enriched using flow cytometry at single cell level. Among the two isolates, IMB169 was found to produce a high level of docosahexaenoic acid. The qualitative and analytical results obtained using electron microscopy and flow cytometry studies were validated by gas chromatography (GC). In addition, a quantitative baseline was established using cell growth, flow cytometry and GC analyses for developing an efficient bioprocessing methodology to selectively enrich thraustochytrids phenotypes with desirable characteristics.

Structure and Strength of Rapidly Quenched Cu-Al2O3 Composites

1998 ◽  
Vol 555 ◽  
Author(s):  
A. I. Il'Insky ◽  
A. S. Terletsky ◽  
E. W. Zozulya
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Strain Hardening ◽  
Vapor Condensation ◽  
High Temperature Annealing ◽  
X Ray ◽  
Transmission Electron ◽  
Three Stages ◽  
High Level

AbstractMicrostructure of dispersion hardened composites (DC) Cu-Al2O3 prepared by simultaneous vacuum vapor condensation of Cu and A12O3 was studied by X-ray diffractometry and transmission electron microscopy methods. After high temperature annealing at 900°C for 2 hours the composites retain the submicrocrystalline structure and high level of strength -0.9 GPa. It has been found that strain hardening of vacuum deposited Cu-A12O3 composites takes place in three stages that is not typical for well-known composites of metallurgical origin.

Visualisation of Electrically Active Areas Using Electron Holography

2002 ◽  
Author(s):  
U. Muehle ◽  
A. Lenk ◽  
M. Lehmann ◽  
H. Lichte
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Electron Holography ◽  
Transmission Electron ◽  
Structural Details ◽  
Different Types ◽  
High Level ◽  
Technical Solutions

Abstract In accordance with the predictions of the International Semiconductor Association, a further decrease in the structural widths of semiconductor devices is expected. For an in-depth characterization of actual structural details, the transmission electron microscopy (TEM)-technique is becoming more and more significant. An urgent requirement is in the visualization of dimensions of the doped regions and estimation of p-n-junctions profile with a high level spatial resolution. The off-axis electron holography, a special TEM-technique, is able to visualize electrically active areas in semiconductors. This article describes a way to achieve sample preparation for TEM-holography from actual memory products and also provides an idea of the potential of this technique for semiconductor failure analysis. It shows that different types and sizes of FET's and testing structures could be visualized by focusing on the physical basics, technical solutions, and sample preparation.

Highly Automated Transmission Electron Microscopy Tomography for Defect Understanding

2011 ◽  
Author(s):  
James J. Demarest ◽  
Hong-Ying Zhai
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Significant Advance ◽  
Data Set ◽  
Root Cause ◽  
Dual Beam ◽  
Resource Needs ◽  
Transmission Electron ◽  
Time Required ◽  
High Level

Abstract Imaging tomography by transmission electron microscopy (TEM) is a technique which has been growing in popularity in recent years, yet it has not been widely applied to semiconductor defect studies and root cause determination [1- 3]. In part this is due to the complex equipment, computing needs, and microscope time required to generate the various images which ultimately compose the data set. However, the latest generation of TEMs—with their high level of stability and automation—are greatly reducing the resource needs to create high quality and informative movies of defects rotating about a central axis. One significant advance is the reduction in time required to fabricate a sample and perform the data acquisition by TEM. Today’s microscopes allow for sample fabrication to take place in a few hours or less and can acquire more than 100 images in about an hour at different sample tilt conditions with minimal analyst intervention. This paper describes using automated TEM sample preparation with dual beam focused ion beams (previously reported [4]) in conjunction with automated tomography software on a state-of-the-art TEM. By using an advanced tomography holder ±70° of tilt can be obtained. This is a powerful way to view defects as the failure can be viewed through more than 90° of rotation. Consequently a more complete understanding of the failure site can be obtained over a typical single projection TEM image. This can greatly facilitate root cause determination in a timely manner.

The reaction of reference commercial nuclear waste glasses during gamma irradiation in a saturated tuff environment

1988 ◽  
Vol 3 (3) ◽  
pp. 576-597 ◽  
Author(s):  
John K. Bates ◽  
William L. Ebert ◽  
Donald F. Fischer ◽  
Thomas J. Gerding
Keyword(s):  
Gamma Irradiation ◽  
Radiation Exposure ◽  
Nuclear Waste ◽  
Current Data ◽  
Solution Chemistry ◽  
Nuclear Waste Repository ◽  
Exposure Rate ◽  
Reaction Products ◽  
High Level Nuclear Waste ◽  
High Level

The effects of gamma irradiation on groundwater and the reaction between groundwater and glass have been investigated at radiation exposure rates of 2 × 105 1 × 103 and 0 R/h. These experiments, which bound the conditions that may occur in a high-level nuclear waste repository located in tuff, have been performed using the actinide-containing glasses ATM-lc and ATM-8, and have been performed for time periods up to 278 days. The experimental results indicate that when only the repository groundwater is present, the pH of the system remains near-neutral, regardless of the radiation field, due to the buffering capacity of the solution. When glass is added to the system, the subsequent reaction is governed by the solution chemistry, which results from a complex interaction between radiolysis products, glass reaction products, and groundwater components. While no long-term reaction trends have been extracted from the current data, it is noted that there are no outstanding differences in the reaction of the glasses as measured by the release of the soluble components B, Mo, and Na, as a function of radiation exposure rate. However, there is a marked difference in the amount of U, Np, and Pu released from the glasses as a function of radiation exposure rate. This difference can be correlated with the pH values of the leachate, with more basic solutions resulting in lower actinide release.

scholarly journals Кристаллографические особенности структуры литых и закаленных сплавов кобальт--ниобий

2020 ◽  
Vol 90 (7) ◽  
pp. 1103
Author(s):  
Ю.В. Хлебникова ◽  
Л.Ю. Егорова ◽  
Т.Р. Суаридзе ◽  
Ю.Н. Акшенцев
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Polymorphic Transformation ◽  
Room Temperature ◽  
Fine Grained ◽  
Α Phase ◽  
Transmission Electron ◽  
Cast Alloys ◽  
High Level ◽  
Subsequent Quenching

By the means of metallography, scanning and transmission electron microscopy, and EBSD-analysis, the features of the structure formation upon β→α (fcc-hcp) - polymorphic transformation in Co - Nb binary alloys were studied. It was shown that upon gradual cooling of the crystallized ingot, in each β-grain of the alloy nucleation of the α-phase crystals of several orientations out of 4 possible in accordance with the Wasserman’s orientational relations occurs. The formation of any of the 4 possible orientations of the α-phase is equally probable. At room temperature, only α (hcp)-martensite was found in the structure of the studied alloys. The misorientation of the substructure in the martensitic crystals length-wise in cast alloys does not exceed 1 deg. After the homogenization and the subsequent quenching in salted water, the structure of Co-Nb alloys does not undergo neither morphological, nor crystallographic changes, but becomes noticeably more fine-grained. In this case, the misorientation of the substructure elements of the martensitic crystals length-wise increases several times, consequent to the high level of quenching microstresses in martensite. No phases with multilayer lattices such as NR martensite were found.

Glass — amorphous?

1988 ◽  
Vol 46 ◽  
pp. 472-473
Author(s):  
Kazue Tazaki ◽  
W. S. Fyfe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Domain Structure ◽  
Nuclear Waste ◽  
Substrate Surface ◽  
Sedimentation Technique ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Analytical Electron Microscope

Glass, amorphous, and noncrystalline materials are important constituents of rocks, soils, marine sediments, and nuclear waste. It has long been recognized that many clay minerals crystallize from noncrystalline precursors, the paracrystalline allophane, and saprolite passing through adsorption and deposition in solution.Three glass materials were examined with a JEOL-JEM 100C at 100 KV and JEOL-JEM 400 EX, TEM-STEM analytical electron microscope at 400 KV. The <2 μm sized fractions were concentrated by the sedimentation technique and pipetted on grids for TEM. Specimens were collected from Michipicoten Island, Canada, and Ilha Bela, Brazil, and compared with a waste form glass.High-resolution transmission electron microscopy clearly shows the rearrangement of the glass framework of 3Å domain structure and growth of the transitional products, primitive clay precursors and 14Å clays.The crystallization may be induced by the domain structure on the substrate surface already existing prior to deposition.

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