Abstract: A tailgate cover includes a flexible panel having a first side, a second side, a first edge, a second edge, a third edge and a fourth edge. The first and second edges are positioned opposite of each other. A bisecting line extends through the first and second edges and divides the panel into a first portion and a second portion. Each of a first elongated strap and a second elongated strap is attached to and extends along a length of a respective one of the first and second edges such that a respective first portion and a second portion of the first and second straps is defined. The first side of the panel is positionable on a tailgate. A securing assembly releasably secures the first and second portions of the first strap together and the first and second portions of the second strap together.

Abstract: An apparatus for detecting changes in chemical or physical parameters, comprises a sensing optical fibre having a core surrounded by a relatively sensitive cladding the absorption spectrum of which varies with changes in chemical or physical parameters when these are applied to the cladding, and a transmissive optical fibre having a core surrounded by a relatively insensitive cladding for connecting at least one end of the sensing optical fiber to a remote light source and a remote detector. The core of the sensing optical fibre has substantially the same diameter as the core of the transmissive fibre and the refractive indices of both the relatively sensitive and the relatively insensitive claddings are less than the refractive indices of the cores of both the sensing optical fibre and the transmissive optical fibre.

Abstract: For detecting changes in chemical or physical parameters an optical fibre core has bonded to its surface a chromophore responsive to the parameter. The core preferably has a porous surface with the chromophore coating extending into the porous structure.

Abstract: Apparatus for monitoring gaseous pollutants (e.g. on a chemical plant) produces two infra-red laser beams having different wavelengths (one corresponding to an absorption line of the gas to be monitored, the other being a reference) which are modulated with different frequencies or phases, and then combined into a single scanning beam. The scanning beam is continuously displaced angularly so as to scan the area to be monitored. A portion of the beam is returned to the apparatus by scattering or reflection, and is measured. By correlating this with the direction of the beam, a plan of the monitored area superimposed with a continuously updated indication of the amount of gas can be displayed e.g. on a VDU.