Ultrasonic Relaxation in Aqueous Mixture of Urea with Enzyme Urease

Abstract

LETTERS TOTHE EDITOR tions for the neutral vowel/o/. Acoustic analysis shows that F1 and F2 of the neutral vowel may correspond to those of/,x/,/e/, or/•/, depending on context. This is to be expected because the primary function of a neutral vowel is to provide a smooth transition (for the articulators) between two consonants. The main distinguishing feature of/o/, when it is present, is its low amplitude and short duration. These prosodic parameters are best indicated by a stress marker and not by the use of a separate phonemic symbol. These considerations suggest that the so-called neutral vowel/o/is best approximated by an allophone of /e/, or/•/depending on context, with appropriate stress indication. When in doubt, remember that its most common occurrence is as an allophone of/•x/. In transcriptions where stress indication is important, one adds the digit 0, 1, or 2 immediately following the vowel symbol to indicate unstressed, secondary stress, and primary stress. This would make the transcription somewhat unreadable, but stress markers can easily be suppressed from listings when readability is important.Some readers might be concerned that using two characters per phoneme might require 12 to 16 bits of valuable computer storage to represent a phoneme. The notation proposed here is intended only for input to or output from the computer. The internal representation of phonemes might be a fixed six-or seven-bit code or variable length code using Huffman coding.The transcription resulting from the use of the notation can indeed be readable, as illustrated by the following transcription of the example given in Dixon and Maxeyl: ,/AIM SAAREE/YOOV REECHT DHIS AWFIS BAI MISTEIK /PLEEZ KANSALT YAR DAREKTAREE Results are reported of the ultrasonic-absorption coefficient and its variation with frequency in an aqueous mixture of urea with enzyme urease. The probable causes for the observed high absorption are examined. THE ULTRASONIC-ABSORPTION METHOD HAS NOW BECOME A USEFUL tool for the study of rapid and reversible processes in fluids. Some of these studies, such as the equilibrium in rotational isomers, 1 dimerization • in carboxylic acid, and ionic dissociation in dectrolytes 3 are already well recognized. However, there have been only a few applications of this method for the study of biological media. This is presumably because of the fact that the reversible fast step in a biological transformation is very often accompanied The third-order elastic moduli of quartz have been measured using a pulseecho interferometer technique. Values for the constants are given and compared with those of previous workers. TaERE HAS BEEN CONSIDERABLE INTEREST RECENTLY IN TIlE NONlinear elastic properties of solids, especially in relation to the propagation characteristics of ultrahigh-frequency elastic waves. The nonlinear behavior may be conveniently described in terms of "third-order" elastic moduli, so called because they appear in polynomial stored-energy functions as coefficients of third-order 640 Volume 44 Number 2 1968