Abstract: An antigenic protein, termed antigen A, present on the cell walls and in tures of Streptococcus mutans, especially genetic group I (serotypes c, e and f) is separated from other antigenic proteins, notably those which cross-react with heart tissue, to give an antigenic preparation which may be used as a vaccine or to raise antibodies for use in protecting against dental caries.Antigen A is one of two major antigenic proteins remaining on cell walls of S. mutans genetic group I after extraction with a boiling 10 g/l liter aqueous solution of sodium dodecyl sulphate for 20 minutes. It has a molecular weight of about 29,000, an isoelectric point of 4.1 to 4.5. Its amino-acid analysis is also given.The antigen also occurs in the culture filtrate and/or cell extract and may be readily purified from these sources by, for example fractional ammonium sulphate precipitation and/or affinity chromatography on immobilized antibody.

Abstract: The invention concerns the detection of contaminant in a stream of gas. Pious methods have either been insufficiently sensitive or have been slow and needed skilled operatives. The present invention allows speedy operation with relatively unskilled operatives. A piezo electrical crystal oscillator (1) is allowed to oscillate for a known period of time and the number of oscillations is counted. For a known time the crystal is exposed to contaminant, and is then allowed to oscillate again for the same period of time as before and the oscillations again counted. The difference in number of oscillations is a measure of the mass of contaminant deposited on the crystal (1). The period of oscillation of the first crystal is determined by a second matched crystal oscillator (2) in which the crystal is exposed to the same environment but not in contaminant. The apparatus has the advantage of being self-zeroing, and the exposed crystal (1) does not need cleaning after each use.

Abstract: An antigenic protein, termed antigen A, present on the cell walls and in tures of Streptococcus mutans, especially genetic group I (serotypes c, e and f) is separated from other antigenic proteins, notably those which cross-react with heart tissue, to give an antigenic preparation which may be used as a vaccine or to raise antibodies for use in protecting against dental caries.Antigen A is one of two major antigenic proteins remaining on cell walls of S. mutans genetic group I after extraction with a boiling 10 g/l liter aqueous solution of sodium dodecyl sulphate for 20 minutes. It has a molecular weight of about 29,000, an isoelectric point of 4.1 to 4.5. Its amino-acid analysis is also given.The antigen also occurs in the culture filtrate and/or cell extract and may be readily purified from these sources by, for example fractional ammonium sulphate precipitation and/or affinity chromatography on immobilized antibody.

Abstract: Apparatus for testing at least one liquid sample, by immersion therein of a probe for coaction between said probe and sample, having a reloadable sample carrier for at least one sample container; a reloadable probe carrier for at least one probe; a frame having locating means for relatively locating the sample carrier and the probe carrier laterally in the frame, parallel motion means for guiding the probe longitudinally into the sample container and stop means for locating the probe at a predetermined distance into the sample container, locking means preventing the probe from being withdrawn more than a predetermined distance in the outward direction from the sample container, timing and control means for releasing said locking means after a predetermined time, and self acting withdrawal means for withdrawing the probe and probe carrier to a position clear of the sample container; the said sample carrier and probe carrier being arranged so as to be severally removable away from the said frame.

Abstract: An optical system for conveying an optical image having two first biconvex od lenses arranged end to end on a common optical axis in spaced relationship, and between said first rod lenses but not in contact with them a pair of second rod lenses also arranged end to end on the same axis, the adjacent ends of the second rod lenses being concave and defining a biconvex cavity which can contain a fluid whereby a fluid lens is formed, the system being substantially symmetrical about a median plane through the biconvex cavity and the modulus of the reciprocal of the radius of curvature of the fluid lens being less than or equal to the modulus of the difference between the reciprocal of the radius of curvature of the convex surfaces of the first rod lenses adjacent to the second rod lenses and the reciprocal of the radius of curvature of the convex surfaces of the second rod lenses adjacent to the first rod lenses.

Abstract: A reel for use upon a cylindrical support on plaster jacket bedframes incorates a ratchetless anti-reverse mechanism which is readily disengageable and which permits continuous adjustment of the position of the reel upon the bedframe. The anti-reverse mechanism comprises a close wound helical spring which has a free diameter less than the diameter of the cylindrical support. The spring is mounted on the cylindrical support and attached by one of its ends to a spool rotatably mounted on the cylindrical support.

Abstract: The invention relates to a vial located in a pocket in a carrier.The pocket has an upwardly opening inlet and a plane, bottom cam surface the vial has a complementary, plane, bottom cam surface. Both cam surfaces are inclined to the axes of the vial and pocket so that on lowering the vial into the pocket through its inlet, the cam surfaces interact so that when the vial is fully home in the pocket, it occupies a predetermined position of angular displacement about the vial axis.The carrier may be in the form of a turntable having a plurality of such pockets around the peripheral region of the turntable. The pockets may open outwardly from the center of the turntable through the peripheral surface of the turntable so that labels fixed and appropriately positioned on the vial walls are visible through the openings in the peripheral surface when the vials are fully home in their pockets.

Abstract: Specimen agitation apparatus comprises a horizontal turntable carrying, and its periphery, a plurality of substantially equally spaced vessels for receiving specimens to be agitated. The turntable is rotated stepwise about its central axis by a stepping motor which applies driving impulses to the turntable so as to cause it to rotate from a first rotational position to a second rotational position, but before coming to rest at the second position the turntable oscillates about the central axis to agitate the specimens.

Abstract: The apparatus comprises a turntable carrying, in a circular array centered n a central rotational axis of the turntable, a plurality of vials extending below the underside of the turntable. A stepper motor imparts stepwise rotational motion to the turntable so that during dwell periods of the turntable, specimens in the vials can be investigated optically.Air in a space below the turntable and bounded laterally and at the bottom by an enclosure is circulated by a rotating vane, and a thermistor, responsive to the temperature in the region of the vials, controls a heater in the space below the turntable so as to maintain the temperature of the vials substantially at a predetermined value.