scholarly journals Physical property comparison of 11 soft denture lining materials as a function of accelerated aging

1993 ◽  
Vol 69 (1) ◽  
pp. 114-119 ◽  
Author(s):  
E.R. Dootz ◽  
A. Koran ◽  
R.G. Craig
Keyword(s):  
Accelerated Aging ◽  
Physical Property

scholarly journals Density Changes in Plutonium Observed from Accelerated Aging using Pu-238 Enrichment

2003 ◽  
Vol 802 ◽  
Author(s):  
B. W. Chung ◽  
S. R. Thompson ◽  
C. H. Woods ◽  
D. J. Hopkins ◽  
W. H. Gourdin ◽  
...  
Keyword(s):  
Accelerated Aging ◽  
Physical Property ◽  
Recoil Nucleus ◽  
Irradiation Damage ◽  
Volume Changes ◽  
Defect Clusters ◽  
Particle Decay ◽  
Lattice Damage ◽  
Property Changes ◽  
Inside Out

Plutonium, because of its radioactive nature, ages from the “inside out” by means of self-irradiation damage and thus produces Frankel-type defects (vacancies and self-interstitial atoms) and defect clusters. The self-irradiation damage in Plutonium-239 occurs mainly by α-particle decay, where most of the damage comes from the U-235 recoil nucleus. The defects resulting from the residual lattice damage and helium in-growth could result in microstructural and physical property changes. Because these self-irradiation effects would normally require decades to measure, with a fraction (7.5 wt%) of Pu-238 is added to the reference plutonium alloy thus accelerating the aging process by approximately 18 times the normal rate. By monitoring the properties of the Pu-238 spiked alloy over a period of about 3.5 years, the properties of plutonium in storage can be projected for periods up to about 60 years. This paper presents density and volume changes observed from the immersion density and dilatometry measurements equivalent to aging the reference plutonium alloys to nine years.

scholarly journals Physical Property Changes in Plutonium Observed from Accelerated Aging using Pu-238 Enrichment

2006 ◽  
Vol 986 ◽  
Author(s):  
Brandon W. Chung ◽  
Bill Choi ◽  
Cheng Saw ◽  
Stephen Thompson ◽  
Conrad Woods ◽  
...  
Keyword(s):  
Ultimate Strength ◽  
Tensile Property ◽  
Aging Process ◽  
Accelerated Aging ◽  
Physical Property ◽  
Tensile Tests ◽  
Weight Percent ◽  
Volume Increase ◽  
Property Changes ◽  
Weapons Grade Plutonium

AbstractWe present changes in volume, immersion density, and tensile property observed from accelerated aged plutonium alloys. Accelerated alloys (or spiked alloys) are plutonium alloys enriched with approximately 7.5 weight percent of the faster-decaying 238Pu to accelerate the aging process by approximately 17 times the rate of unaged weapons-grade plutonium. After sixty equivalent years of aging on spiked alloys, the dilatometry shows the samples at 35°C have swelled in volume by 0.15 to 0.17 % and now exhibit a near linear volume increase due to helium in-growth. The immersion density of spiked alloys shows decrease in density, similar normalized volumetric changes (expansion) for spiked alloys. Tensile tests show increasing yield and engineering ultimate strength as spiked alloys are aged.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

A photoelectron microscope study of surfaces

1989 ◽  
Vol 47 ◽  
pp. 10-11
Author(s):  
W. Engel ◽  
M. Kordesch ◽  
A. M. Bradshaw ◽  
E. Zeitler
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Field Strength ◽  
Uv Light ◽  
Physical Property ◽  
Photon Flux ◽  
Mercury Lamp ◽  
Object Surface ◽  
The Sixties ◽  
Physical Features

Photoelectron microscopy is as old as electron microscopy itself. Electrons liberated from the object surface by photons are utilized to form an image that is a map of the object's emissivity. This physical property is a function of many parameters, some depending on the physical features of the objects and others on the conditions of the instrument rendering the image.The electron-optical situation is tricky, since the lateral resolution increases with the electric field strength at the object's surface. This, in turn, leads to small distances between the electrodes, restricting the photon flux that should be high for the sake of resolution.The electron-optical development came to fruition in the sixties. Figure 1a shows a typical photoelectron image of a polycrystalline tantalum sample irradiated by the UV light of a high-pressure mercury lamp.

Investigating the Multimodal Nature of Human Communication

2009 ◽  
Vol 23 (2) ◽  
pp. 63-76 ◽  
Author(s):  
Silke Paulmann ◽  
Sarah Jessen ◽  
Sonja A. Kotz
Keyword(s):  
Visual Information ◽  
Empirical Studies ◽  
Physical Property ◽  
Event Related Potentials ◽  
Accurate Information ◽  
Human Communication ◽  
Channel Condition ◽  
Prosodic Cues ◽  
Early Processing ◽  
Related Potentials

The multimodal nature of human communication has been well established. Yet few empirical studies have systematically examined the widely held belief that this form of perception is facilitated in comparison to unimodal or bimodal perception. In the current experiment we first explored the processing of unimodally presented facial expressions. Furthermore, auditory (prosodic and/or lexical-semantic) information was presented together with the visual information to investigate the processing of bimodal (facial and prosodic cues) and multimodal (facial, lexic, and prosodic cues) human communication. Participants engaged in an identity identification task, while event-related potentials (ERPs) were being recorded to examine early processing mechanisms as reflected in the P200 and N300 component. While the former component has repeatedly been linked to physical property stimulus processing, the latter has been linked to more evaluative “meaning-related” processing. A direct relationship between P200 and N300 amplitude and the number of information channels present was found. The multimodal-channel condition elicited the smallest amplitude in the P200 and N300 components, followed by an increased amplitude in each component for the bimodal-channel condition. The largest amplitude was observed for the unimodal condition. These data suggest that multimodal information induces clear facilitation in comparison to unimodal or bimodal information. The advantage of multimodal perception as reflected in the P200 and N300 components may thus reflect one of the mechanisms allowing for fast and accurate information processing in human communication.

Effect of Electrolyte Compositions on the Physical Property and Surface Morphology of Copper Foil

2010 ◽  
Vol 48 (10) ◽  
pp. 951-956 ◽  
Author(s):  
Tae-Gyu Woo ◽  
Il-Song Park ◽  
Woo-Yong Jeon ◽  
Eun-Kwang Park ◽  
Kwang-Hee Jung ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Copper Foil ◽  
Physical Property

Assessment of Color Stability of Treated Leathers with Silicone Oil and Polyethylene Glycol

2014 ◽  
Vol 1 (1) ◽  
pp. 24-34
Author(s):  
Alireza K. ◽  
Hossein Ahmadi ◽  
Mohsen Mohammadi
Keyword(s):  
Ascorbic Acid ◽  
Polyethylene Glycol ◽  
Treatment Process ◽  
Color Change ◽  
Silicone Oil ◽  
Accelerated Aging ◽  
Color Stability ◽  
Antioxidant Additive ◽  
Before And After ◽  
Aesthetic Values

Lubricants and leather dressings are the most common treatments of dry and water logged historical leathers. Color change has a great importance during the time and treatment process, due to visual and aesthetic values of historic leather relics. Polyethylene glycol (PEG) and silicone oil (SiO) are frequently used leather dressings in the conservation procedures. Therefore, color stability of treated leathers with PEG and SiO were investigated before and after heat accelerated aging. Moreover, application of ascorbic acid was evaluated as an antioxidant additive for PEG (PEG+AA).Color change after treatment and aging were studied by colorimetry technique in the CIE *L*a*b system. Results indicated to severe color alteration in PEG treated and aged leathers with or without ascorbic acid. Whereas, SiO treated samples showed better stability and minimum color shift after aging. Silicone oil was characterized as the best dressing for historical leathers with compared to PEG and PEG+AA, due to its high stability and aesthetical properties.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

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