Abstract: This invention relates to enzyme assays and substrates for use in such assays. The presence or absence of certain enzymes in vivo is a useful indicator of illness or deficiency in the organisms concerned. Enzymes are also useful in monitoring microbial growth in fermentors and in the food industry and are important in enzyme-linked immunosorbent assays (ELISA), and in the characterization of bacterial species in culture. Disclosed is a reagent for enzyme assay comprising a substrate consonant with a given enzyme to be assayed, labelled with a chromogenic group which, on action of the given enzyme, is liberated to give a colored product. Also disclosed is a kit for the assay of an enzyme comprising the reagent of the disclosed invention.

Abstract: A device to give an indication of the passage of a pig through a pipeline and methods of performing various pipeline operations using the device are described. The device has a magnetic sensor based on a dip needle and the output of the sensor controls a flag actuating mechanism. Passage of a pig beneath a pig indicating device causes a flag to be raised giving a visual indication that the pig has passed that location. Methods are described in which one or more devices are used to find a lost pig, for accurately locating a defect in a pipeline, for determining if a pig has been correctly launched or received, and for determining and controlling the speed of a pig in a pipeline.

Abstract: A pipeline crawler comprises a wheeled power unit and a tractor unit having a plurality of driven wheels for engagement with the interior wall of a pipeline. A flexible power transmission extends from the power unit to the tractor unit for driving the driven wheels and includes a relational connection to permit rotary movement of the tractor unit relative to the power unit.

Abstract: An enzyme assay reagent comprises a substance which is capable of interaction with the enzyme to give rise to the formation of a compound of formula X--A--Y--NO.sub.2, wherein A comprises an aromatic nucleus, X comprises an auxochromic group and Y comprises an unsaturated group which is capable of transmitting electron resonance between the aromatic nucleus and the nitro substituent, said compound per se being capable of producing a visual signal which is easily discernible by eye.

Abstract: Novel sugar acetals such as those of formula ##STR1## where R.sup.a is hydrocarbyl; R.sup.b and R.sup.c are hydrogen or hydrocarbyl; R.sup.3' R.sup.4' and R.sup.6' are hydrogen or R.sup.4' with R.sup.3' or R.sup.6' is ##STR2## are made from 1,4-linked reducing disaccharides by a new exchange acetalation process in which the solvent is omitted. The sugar acetals have free hydroxy groups on the ring which groups can be converted to other substituents, e.g. chlorodeoxy or fatty acid acyl. After deprotection, the corresponding derivative of the initial disaccharide is obtained.