Abstract: In a reserve battery initiator a unitary moulded ampoule (10) containing an electrolyte comprises two portions conjoined by a mechanically weak section (11). The ampoule (10) may be ruptured by a striker (3) which is released when the initiator is subjected to sufficient an accelerative force to overcome a detent mechanism. The ampoule may also contain an insert (12) to transmit to the weak section the force imparted by the striker. The insert (12) may additionally have a cutting effect on the weak section (11). Conveniently the insert is in the form of a frustrum with a narrow end contiguous with the inner face of the ampoule at the location where the striker (3) impacts and a wide end contiguous with the inner face of the weak section (11).

Abstract: A liquid crystal for use in liquid display devices comprises at least one material from group 1 comprising: ##STR1## at least one of the group 1 materials having n=2, or 4; and at least one material from group 2 comprising: ##STR2## together with an ester liquid crystal material. The ester forms between 10% and 90% (preferably between 30% and 70%) by weight of the total mixture and the group 2 material forms between 5% and 30% by weight of the total mixture.Examples of the esters have the general formula ##STR3## where R.sub.1, R.sub.2 represent alkyl or alkoxy groups, and ##STR4## where R.sub.3, R.sub.4 represent alkyl groups. All alkyl and alkoxy end groups are unbranched.

Abstract: A method of making an adhesive bond, particularly suitable for underwater repairs consists of impregnating compliant foam material having an open cell structure with a thermosetting resinous adhesive, applying the foam to a substrate to be bonded or a puncture therein and applying pressure to the foam to immobilize the adhesive within the foam.

Abstract: An antigenically-active cell envelope fraction from bacterial cells, especially Bordetella pertussis, may be isolated by disrupting the cells, separating the cell envelopes from the other cell components, extracting the separated envelopes with a solution of a zwitterionic surfactant and precipitating the cell envelope preparation from the resulting extract by the addition of a lower alkyl (C.sub.1 to C.sub.5) alcohol, preferably ethanol. The preferred extractant is an N, N, N-trialkyl zwitterionic compound especially an N, N, N-trialkyl-.alpha.-amino acid or an N, N, N-trialkyl amine oxide.The cell envelope fraction obtained from B. pertussis is highly protective against whole bacteria when tested by standard vaccine mouse potency assay and has a greatly reduced lipopolysaccharide content compared with either whole cells or crude cell envelopes, greatly reducing the risk of undesirable side-effects from vaccination.

Abstract: The porosity of bulk alloys produced by deposition of the components of the alloy from the vapor phase can be reduced if the surface of the alloy is mechanically worked, preferably by a peening action, during the course of the deposition.Suitable apparatus for mechanically working the surface of the alloy are sets of hammers or flails driven by a suitable means that they strike the surface of the alloy with sufficient force to flatten asperities produced during the course of the deposition and preferably sufficient to remove porosity adjacent to the surface, yet do not at the same time grossly distort the surface of the alloy.