Understanding how natural Cs, Rb, and K have been redistributed in Savannah River Site (SRS) soils during pedogenesis is important to understanding how radiocesium released to the soils will behave over the long term. In this effort, it is important to distinguish K that has participated in mineral-water reactions from that still residing in primary silicate structures, particularly in the clay fraction. The impact of different degrees of acid extraction on K and radiogenic Ar in bulk soil and in clay from five SRS soil samples has been determined. Strong treatment (50% HNO3, three hours, 100°C) releases K from primary minerals, as shown also by a concomitant release of radiogenic Ar, but a more moderate treatment (6% HNO3, three hours, 80°C) does not release K. K in the clay fraction is mostly nonexchangeable K in remnants of primary mica, and clay K-Ar age values near 300 Ma indicate the mica originated in the Appalachian mountain belt.

No description available.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1970. / Includes bibliographical references (p. 85-88).

Profiles for electron density and temperature were determined in a self-consistent way using line emission spectroscopy and collisional radiative models for neutral and singly ionized Argon (Ar I and Ar II) in the Texas Helimak. Neutral Argon density profiles were calculated using a kinetic gas model. Electron-impact excitation and Ionization rates were corrected to account for the electron velocity distribution deviating slightly from a true Maxwellian distribution due to inelastic electron-neutral collisions. Results show an electron temperature which roughly agrees with probe diagnostics. This method gives an electron density that is about twice as high, which may be possible from a power balance perspective. / text

The most commonly used method of euthanasia of laboratory rodents is exposure to carbon dioxide (CO₂), but recent studies have shown that rodents find this gas aversive. The aim of my thesis was to evaluate rat aversion to inhalant agents that could be used as humane alternatives to CO₂. The first study used approach-avoidance testing to examine rat responses to argon-induced hypoxia when argon was introduced at flow rates of 40-239% of the test cage volume per min. Rats never remained in the test cage long enough to lose consciousness when tested with argon. They consumed fewer reward items, stopped eating sooner, and left the test cage more quickly than when tested with air. Rats stopped eating and left the test cage when the oxygen (O₂) concentration had dropped to about 7.7 and 6.8%, respectively, but these O₂ concentrations are too high to cause unconsciousness. Although humans exposed to hypoxia report only subtle symptoms that include cognitive impairments and light headedness, rats are burrowing rodents and could therefore be more sensitive to these effects. I conclude that argon is not a humane alternative to CO₂. The second study used approach-avoidance testing to evaluate rat responses to different concentrations of the inhalant anaesthetics halothane and isoflurane introduced with vaporizers or from soaked cotton balls. On the first day of exposure to anaesthetics, most rats remained in the test cage until they were ataxic and showing difficulty returning to the home cage. On subsequent days of testing most rats left the test cage within seconds, but if given the option, all promptly returned and stayed until they were ataxic, indicating that the learned aversion is transient. Rats were likely sedated by the time they chose to leave, suggesting that forced exposure from the onset of aversion until loss of consciousness is less of a welfare concern than forced exposure to non-sedating agents. I suggest that the use of inhalant anaesthetics for inducing unconsciousness prior to euthanasia is a more humane method than the commonly used CO₂.

No description available.

No description available.

Atomic lifetimes of selected levels in Neon I and Argon I were measured using a method of delayed coincidence. Pulsed rf was used to excite a discharge tube containing the neon and argon gas. The radiation emitted from the excited atoms of the gas was passed through a monochromator so only the desired wavelength would be observed. Each time an excitation pulse ended, the decay of light intensity was detected by a photomultiplier tube. By measuring the decay time of the light intensity using the delayed coincidence technique, the average lifetime of the desired level was determined. The values of lifetimes determined in this study were found to contain considerable error. Several factors contributing to these errors were thought to be the shape of the rf pulses and an effort known as cascading which was caused by the use of rf for excitation of the gas.

Experiments are described in which the momentum flux of gas atoms, remitted normal to the surface of a hot clean tungsten ribbon immersed in a low pressure of helium or argon, is measured with a torsion balance and the thermal accommodation coefficient deduced. Data are presented in which the tungsten temperature range was 700 to 1900 K for helium and 1100 to 1700 K for argon. If it is assumed that the normal remitted momentum flux is that expected on assumption of the cosine emission relation, accommodation coefficients much larger (and for argon physically impossible) than those found previously by other workers are implied. A model is proposed which assumes that atoms impinging on and remitted from the hot tungsten ribbon conserve momentum in directions parallel to the surface. This results in a remitted flux, in the direction of the normal, greater than the cosine relation would predict. The resulting accommodation coefficients are then of the same order as those found using the total heat loss method. The method here reported is believed to be novel. Its accuracy increases with the temperature of the hot solid. It permits the measurement of translational thermal accommodation without relying on the temperature coefficient of resistance of the solid and hence is applicable to alloys and to non-metals. For metals., which have a normal temperature coefficient of resistance, the method allows translational accommodation to be measured and internal energy accommodation to be deduced.

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1966. / Bibliography: leaves 156-168. / xiii, 168 l illus. (part mounted), tables