A method based on temperature-conditional resistance to thymineless death has been designed to facilitate the isolation of amino acid-activating enzyme mutants. This method may be modified to obtain a greater or lesser proportion of activating enzyme mutants. In the latter instance, an increased proportion of temperaturesensitive macromolecule mutants of other types is obtained. Additional uses of this procedure are discussed.

The polymerization of methyl methacrylate initiated by 2,2′‐azoisobutyronitrile in the presence of halogenated benzenes and naphthalene has been investigated. In each case the order of reaction with respect to monomer is apparently of an order less than unity. Suggestions as to the possible participation of the solvent in the initiation process are discussed and shown to be in agreement with experimental measurements.

The purpose of the study was to determine the effects of ultrasonic treatment on muscle microstructure, breaking strength, cook yield, and protein extractability of ground cured ham rolls. A miniaturized system was designed which subjected ground ham to slow mixing and ultrasonic treatment. The samples were mixed for various times up to 2 hr, then stuffed into stoppered glass tubes for cooking in 80°C water bath. Controls were treated similarly, but without ultrasonic treatment. Results showed that ultrasound caused changes in muscle microstructure, increased breaking strength as measured in g/cm' on an Instron Universal Testing Machine, decreased cooking loss and increased the extractability of salt-soluble protein. Ultrasound had no effect on the extractabihty of water-soluble protein.

No abstract

The pressure of a condensible gas such as di-p-xylylene (parylene dimer) or p-xylylene (parylene monomer) may be determined by using a heated thermocouple gauge to retard absorption or polymerization on the gauge elements. An equation has been derived which relates the voltage response of a compensated thermocouple gauge to the true pressure of the system at gauge operating temperatures in the range 25 °–300 °C. Correlation of data and theory have been found using air as a standard reference. Semi-empirical curves fitted to the data for parylene diradical (monomer) shows that the specific heat calculated from the derived equation agrees with theoretical expectations. The specific heats calculated from parylene dimer curves show these values to pass through a maximum at 400 °–450 °C. This corresponds to an inflection point in the gauge response curve and also to the conversion temperature of parylene dimer to parylene monomer.