Abstract: Artificial cervical fluid is disclosed that contains a mucilaginous extract from the okra plant. The mucilaginous extract can be produced using a hot aqueous extractant or cold extraction process followed by separation of larger particles from the extract. The extract finds many uses, for example as a sperm storage medium, a sperm freezing medium, a sexual lubricant, an artificial insemination medium, and an in vitro fertilization medium.

Abstract: Commutator segment shapes are derived, in relation to machine parameters, for which the current density over the trailing edge of the brush is maintained constant, to prevent sparking. The preferred shape is such that the area of contact between the segment and a linear brush increases initially in a single step to half the total area and subsequently increases progressively more slowly; in an alternative shape, the subsequent rate of increase is linear. Suitable brushes to maintain uniform contact in crossing segment boundaries are preferably of the carbon-fibre type.