Unequal Separation Research Articles

Corrections for the Oscillating-Disk Viscometer

Abstract The paper reviews existing theories of the oscillating-disk viscometer and demonstrates their inadequacy. Using the results obtained previously by Kestin and Persen together with an empirical assumption that the edge-correction factor is proportional to the ideal viscous torque pieced together from the infinite-disk and infinite-cylinder solutions, the authors are able to develop working formulas which, in addition to the edge effect, include the effect of wire damping and unequal separation. The effect of a stem is discussed separately and shown to be negligible. Some remarks are made about the decrement-period relationship. The assumptions are compared with experimental results which demonstrate that for a given suspension system the edge-correction factor C depends on the dimensionless ratio x0 = δ/R (δ = √[ν/ω0] is the average boundary-layer thickness and R is the external radius of the disk) in a unique way. This shows that the use of the authors’ equations together with a suitable calibration procedure should lead to reliable values of viscosity.

Megagametophyte Development in a Triploid Tulip

1. The megagametophyte of Inglescombe Yellow, a triploid tulip, is of the Fritillaria-type. 2. During the meiotic prophase of the first division trivalents, bivalents, and univalents were observed. 3. The occurrence of lagging chromosomes and micronuclei was infrequent. 4. There was unequal separation of the chromosomes in both meiotic and subsequent divisions. 5. The relation of these observations to triploid progeny is discussed.