An integrated experimental and computational investigation of defect and microstructural effects on thermal transport in thorium dioxide

Thorium is more abundant in nature than uranium and thorium fuels can breed fissile U-233 fuel that can be used in various types of nuclear reactors. Moreover, thorium dioxide has drawn interest from researchers due to its relatively superior thermal properties when compared to conventional uranium dioxide fuel pellets. In this study, thermal transport in thorium dioxide is investigated using reverse non-equilibrium molecular dynamics. The thermal conductivity of bulk thorium dioxide was measured to be 20.8 W/m-K and the phonon mean free path was estimated to be between 7 ∼ 8.5 nm at 300 K. It was also observed that the thermal conductivity of thorium dioxide has a strong dependency on temperature; the thermal conductivity decreases with an increase in the temperature. Moreover, by simulating thorium dioxide structures with different lengths at different temperatures, it was also identified that short wavelength phonons dominate thermal transport in thorium dioxide at high temperatures, resulting in decreased intrinsic phonon mean free paths and minimal effect of boundary scattering while long wavelength phonons dominate the thermal transport in thorium dioxide at low temperatures.

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Thermal transport in thorium dioxide

Nuclear Engineering and Technology ◽

10.1016/j.net.2018.02.002 ◽

2018 ◽

Vol 50 (5) ◽

pp. 731-737 ◽

Cited By ~ 4

Author(s):

Jungkyu Park ◽

Eduardo B. Farfán ◽

Christian Enriquez

Keyword(s):

Thermal Transport ◽

Thorium Dioxide

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Ultrastructural Localization of Acid Mucosubstance in Skeletal Muscle

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060271 ◽

1967 ◽

Vol 25 ◽

pp. 52-53 ◽

Cited By ~ 2

Author(s):

William J. Dougherty ◽

Samuel S. Spicer

Keyword(s):

Striated Muscle ◽

Divalent Cations ◽

Ultrastructural Localization ◽

Major Elements ◽

Frozen Sections ◽

Thorium Dioxide ◽

Iron Solution ◽

Coupling System ◽

Psoas Muscles ◽

Formalin Fixed

In recent years, considerable attention has focused on the morphological nature of the excitation-contraction coupling system of striated muscle. Since the study of Porter and Palade, it has become evident that the sarcoplastic reticulum (SR) and transverse tubules constitute the major elements of this system. The problem still exists, however, of determining the mechamisms by which the signal to interdigitate is presented to the thick and thin myofilaments. This problem appears to center on the movement of Ca++ions between myofilaments and SR. Recently, Philpott and Goldstein reported acid mucosubstance associated with the SR of fish branchial muscle using the colloidal thorium dioxide technique, and suggested that this material may serve to bind or release divalent cations such as Ca++. In the present study, Hale's iron solution adapted to electron microscopy was applied to formalin-fixed myofibrils isolated from glycerol-extracted rabbit psoas muscles and to frozen sections of formalin-fixed rat psoas muscles.

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High Voltage Transmission Microscopy of Surveyor III Camera Shrouds

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064748 ◽

1971 ◽

Vol 29 ◽

pp. 138-139

Author(s):

W. R. Duff ◽

L. E. Thomas ◽

R. M. Fisher ◽

S. V. Radcliffe

Keyword(s):

Alloy Sheet ◽

Transmission Microscopy ◽

Television Camera ◽

Window Method ◽

Transmission Electron ◽

Microstructural Effects ◽

Lunar Environment ◽

Successful Retrieval ◽

Materials Used ◽

Abrasive Paper

Successful retrieval of the television camera and other components from the Surveyor III spacecraft by the Apollo 12 astronauts has provided a unique opportunity to study the effects of a known and relatively extensive exposure to the lunar environment. Microstructural effects including those produced by micro-meteorite impact, radiation damage (by both the solar wind and cosmic rays) and solar heating might be expected in the materials used to fabricate the spacecraft. Samples received were in the form of 1 cm2 of painted unpainted aluminum alloy sheet from the top of the camera visor (JPL Code 933) and the sides (935,936) and bottom (934) of the lower camera shroud. They were prepared for transmission electron microscopy by first hand-grinding with abrasive paper to a thickness of 0.006". The edges were lacquered and the sample electropolished in 10% perchloric methanol using the “window” method, to a thickness of ~0.001". Final thinning was accomplished by polishing 3 mm punched disks in an acetic-phosphoric-nitric acid solution.

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Ultrastructure of Lymphatic Capillaries in the Transport of Colloidal Particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060945 ◽

1967 ◽

Vol 25 ◽

pp. 186-187

Author(s):

L. V. Leak ◽

J. F. Burke

Keyword(s):

Connective Tissue ◽

Colloidal Particles ◽

Ultrastructural Level ◽

Vital Role ◽

Time Intervals ◽

Thorium Dioxide ◽

Lymphatic Capillary ◽

Tissue Area ◽

Rapid Removal ◽

Tissue Fluids

The vital role played by the lymphatic capillaries in the transfer of tissue fluids and particulate materials from the connective tissue area can be demonstrated by the rapid removal of injected vital dyes into the tissue areas. In order to ascertain the mechanisms involved in the transfer of substances from the connective tissue area at the ultrastructural level, we have injected colloidal particles of varying sizes which range from 80 A up to 900-mμ. These colloidal particles (colloidal ferritin 80-100A, thorium dioxide 100-200 A, biological carbon 200-300 and latex spheres 900-mμ) are injected directly into the interstitial spaces of the connective tissue with glass micro-needles mounted in a modified Chambers micromanipulator. The progress of the particles from the interstitial space into the lymphatic capillary lumen is followed by observing tissues from animals (skin of the guinea pig ear) that were injected at various time intervals ranging from 5 minutes up to 6 months.

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Low-temperature annealing of YBa2Cu3O7-x

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100120849 ◽

1992 ◽

Vol 50 (1) ◽

pp. 88-89

Author(s):

R.L. Sabatini ◽

Yimei Zhu ◽

Masaki Suenaga ◽

A.R. Moodenbaugh

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Low Temperature ◽

Oxygen Diffusion ◽

Diffusion Rate ◽

Oxygen Depletion ◽

Low Temperature Annealing ◽

Transmission Electron ◽

Microstructural Effects ◽

Oxygen Diffusion Rate

Low temperature annealing (<400°C) of YBa2Cu3O7x in a ozone containing oxygen atmosphere is sometimes carried out to oxygenate oxygen deficient thin films. Also, this technique can be used to fully oxygenate thinned TEM specimens when oxygen depletion in thin regions is suspected. However, the effects on the microstructure nor the extent of oxygenation of specimens has not been documented for specimens exposed to an ozone atmosphere. A particular concern is the fact that the ozone gas is so reactive and the oxygen diffusion rate at these temperatures is so slow that it may damage the specimen by an over-reaction. Thus we report here the results of an investigation on the microstructural effects of exposing a thinned YBa2Cu3O7-x specimen in an ozone atmosphere using transmission electron microscopy and energy loss spectroscopy techniques.

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Experimental and Computational Investigation of Guided Waves in a Human Skull

Ultrasound in Medicine & Biology ◽

10.1016/j.ultrasmedbio.2020.11.019 ◽

2020 ◽

Author(s):

Christopher Sugino ◽

Massimo Ruzzene ◽

Alper Erturk

Keyword(s):

Guided Waves ◽

Computational Investigation ◽

Human Skull

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