Muon diffusion and trapping studies in high purity vanadium

We present the first results of a study of the effects of varying impurity concentration on the temperature dependence of the depolarization rate of positive muons implanted into vanadium. Data are reported for the most highly purified polycrystalline sample yet measured, and the same sample subsequently doped with about 500 ppm oxygen by weight. The data for the pure sample shows a low depolarization rate (<.15 sec^–1) at all temperatures measured, showing a broad minimum centered at 35 K, followed by a sharp peak near 90 K and a rapid drop to negligible values at 200 K. The data is contrasted with previously published data [2] on less pure samples, and calls into question previous interpretations of the behavior of the ⁺ at low temperatures in impure vanadium [1] as one-phonon-assisted tunneling.This work was supported by the U. S. Department of Energy     

Time‐Varying Flexible Least Squares for Thermal Desorption of Gases

Time‐varying linear regression via flexible least squares is used to determine temperature‐dependent kinetic parameters during low‐pressure, steady‐state, temperature‐programmed desorption from catalytic surfaces. The flexible least squares approach optimizes time‐varying parameters by minimizing dynamic and measurement discrepancies between a linear theoretical model and experimental data using linear regression. The effectiveness of this approach is demonstrated by calculation of accurate temperature‐dependent activation energies, preexponential factors, and differential conversion functions for the evolution of 3‐methyl‐2‐oxetanone (β‐lactone) during the selective oxidation of isobutane over aluminum phosphomolybdates.     

Polymeric Sorbents for Bile Acids. III. Hydrophilic and Hydrophobic Models 0f Cholestyramine

Abstract

A study is presented of the binding of glycocholate bile salt anions by crosslinked polymeric beads consisting of either an acrylamide or a Merrifield resin. Various amine-containing pendant groups have been synthesized onto the functional sites of the backbones of these resins, thus forming bile acid sorbents. Based on the effects of systematic changes in the structure of the functional groups on the sorption isotherms, it is shown that the extent of binding is favored by changes that increase the basicity, especially quaternization. On the other hand, sorption is inhibited by extensive crosslinking. It is concluded that the sorption of glycocholate by these sorbents involves an ion-exchange mechanism.     

Some Observations on Measuring Sound Speeds in Polymers Using Time-of-Flight

Experimental Techniques - The time-of-flight method has been used to measure the longitudinal and shear wave speeds in six polymers (polyether ether ketone [PEEK], PEEK with 10% carbon fibers,...     

MATHEMATICS,LANGUAGE AND DERRIDA

Abstract

Derrida's revolutionary work in the study of language has seriously challenged the way in which we see words being attached to meanings. This paper makes tentative steps towards examining how his work might assist us in understanding the way in which our attempts to describe or capture our mathematical experiences modify the experience itself. In doing this we draw on the work of Jacques Derrida and John Mason in locating possible frameworks through which to conceptualise the relationship between language and mathematical cognition. It concludes that mathematical meaning never stabilises since it is caught between the individual's ongoing experience and society's ongoing renewal of its conventions. That is, mathematics, language and the human performing them are always evolving in relation to each other.