Ministry of Supply

About: Ministry of Supply is a based out in . It is known for research contribution in the topics: Polarography & Bacillus (shape). The organization has 416 authors who have published 355 publications receiving 8951 citations. The organization is also known as: MoS.

Observations on foaming and its inhibition in a bacterial culture

Abstract: SUMMARY: Inhibition of foaming in a continuous culture of bacteria has been studied. At first, foaming was inhibited by the addition of antifoam to the culture only when a foam layer was present. When the antifoam was added in this way foaming often became intense and antifoam additions had to be more and more frequent. In a preferred method the antifoam was added at regular intervals which were sufficiently short to inhibit foaming completely throughout the intervening periods. This method required less antifoam than the other. The effects of foaming in cultures, its causes, and allied problems are discussed.

A precision dual bridge for the standardization of admittance at very high frequencies

Abstract: The need is stated for a more accurate means of admittance or impedance measurement in order that a general improvement can be made in the accuracy of measurement of other electrical quantities at radio frequencies. A description is given of a precision twin-T dual bridge having a range of admittance measurement associated with coaxial systems between 3 Mc/s and 300 Mc/s. The inaccuracy of measurement does not exceed 0.2% on either component of a complex admittance at a frequency of 200 Mc/s. The calibration of the bridge is based on a range of coaxial susceptance standards whose parameters are calculated from length and time measurements. The dual feature of the bridge enables the true r.f. conductance of its internal standard resistor to be established in terms of these standards; the uncertainty of this determination is not greater than 0.1% for frequencies up to 250 Mc/s. The importance to be attached to the design of coaxial terminations for measuring instruments and standards at these frequencies is emphasized. A practical design is detailed for a coaxial terminal for precision admittance and impedance measuring instruments, and mention is made of a proposed universal coaxial connector system for precision radio-frequency measuring instruments of all types.