Ultrasonic cleaning uses high-frequency sound waves to induce cavitation within a cleaning, medium. During cavitation, millions of small bubbles form and collapse, resulting in agitation proportional to the energy put into the solution. The making and breaking of these bubbles produce the scrubbing action associated with ultrasonic cleaning.

Abstract: "This is a selective bibliography of books and periodical articles relating to die design of hot presses. Sources consulted include: ASM Review of Metal Literature, 1950-1954; Chemical Abstracts, 1950-1055; Engineering Index, 1950-1055; Industrial Arts Index, 1950-March 1957; Metallurgical Abstracts, 1950-1953; Nuclear Science Abstracts, 1950-March 1957; Physics Abstracts, 1950-1955; the library card catalog, and the Technical Information Division AEC card catalog."

A memorandum report on test drilling of areas of anomalous radioactivity.

The transition region between two parts of a pile which have different compositions is investigated. In the case where the moderator is the same in both parts of the pile, it is found that the diffusion constant times thermal neutron density plus diffusion constant times fast neutron density satisfied the use pile equations everywhere, right to the boundary. More complicated formulae apply in a more general case.