Direct Mounting Research Articles

The Measurement of Ultrasonic Attenuation in Solids by the Pulse Technique and Some Results in Steel

Pulse techniques for the measurement of attenuation in solids have been extended and refined sufficiently to obtain dependable measurements over a frequency range from 5 to 50 megacycles. Understanding of the relative importance of beam spreading, geometrical boundaries, and method of coupling has been improved. Coupling by means of water buffer and direct mounting is discussed in detail. Attenuation measurements in the frequency range from 5 to 50 megacycles have been made on chrome molybdenum steel specimens, and these measurements have shown large differences in ultrasonic attenuation for samples of the same chemical composition but different heat treatment. The resulting differences are connected with anisotropy which appears in the photomicrographs. The attenuation measurements are quite sensitive to heat treatment and other factors. The application of the methods to metallurgical problems and the physics of solids is suggested.

Electron Microscopy of Sickle Cells

SummaryA modification of the Beck-Hertz technic permits direct mounting of sickle cells for electron microscopy studies. Electron micrographs of sickle cells essentially confirm the findings of Diggs and Bibb and substantiate pertinent optical studies as to structural detail. In addition, both corpuscular hemoglobin-membrane relationships and polar filament structure are further visualized.

A Modified Technic for Salivary-Gland Chromosomes

This technic was worked out for making permanent mounts of salivary-gland squashes of strains and species of Drosophilidae, which yield material difficult to work with. It includes a prior fixation in a modified Carnoy's fluid, staining in solutions of orcein in 60% or 70% acetic acid, part dehydration in the vapor and liquid of a 95% solution of alcohol, and direct mounting in Euparal by means of the drainage-method.