Abstract: A method for determining NADH and/or NADPH-concentrations, for instance in NADH- or NADPH transforming systems, the method comprising the step of bringing the sample subject to determination in contact with the bioluminescent reagent based on bacteria luciferase, NAD(P)H-FMN oxidoreductase, FMN and aliphatic aldehyde, whereby a reaction takes place, where NAD(P)H is oxidized and FMN is reduced, the reaction being catalyzed by the oxidoreductase, whereafter the FMNH.sub.

Abstract: Disturbances caused by static electricity in liquid scintillation counting are eliminated by an ionizing device. A liquid scintillation counter in a measurement chamber surrounded by a radiation protective device measures nuclear fissions occurring in a sample bottle moved into the measurement chamber along a predetermined path. The ionizing device ionizes the air by producing positive and negative ions in the path followed by the sample bottle into the measurement chamber. Ions produced by the ionizing device on the sample bottle before the bottle enters the chamber neutralize any electrostatic charge on the bottle.

Abstract: An improved method of determining the nature of a substance by fluoroscence spectroscopy wherein a fluorescent marker is coupled to the molecules of the substance comprises the use of a marker having a longer period of fluorescence than those of possible sources of noise and by employing an exciting radiation pulse of short duration so that the fluorescence of the marker is detected after the objectionable sources of fluorescence have ceased; the marker including a fluorescent lanthanide chelate complex.

Abstract: A system for the measurement of radioactivity of a number of radioactive samples by a radiation detector which will be affected by radiation from a number of other sources having predetermined locations in addition to the sample being measured consists of first measuring the values of activity measured by the detector when a standard radiation source of known activity is placed in the detector and in each of the predetermined locations to determine the effect of the other sources on the measurements of the detector, storing the values thus determined and thereafter compensating the values of radioactivity of each sample measured by the detector with the stored values to obtain the actual values of radioactivity of the samples.

Abstract: A device to be used in an automatic gamma counter to move sample holders (4) into a measuring chamber (6). The device comprises a slide (1) which moves the holders into the measuring chamber (6) and at the entering completely seals the chamber.

Abstract: A method and apparatus for measuring the flow rate of gases comprises the placing of a small radioactive source material in the path of the gas flow, establishing an electrical potential between one electrode and two other electrodes disposed transversely of the gas flow path from the first electrode and in the direction of gas flow from each other, and comparing the currents generated between the electrodes as a function of the rate of gas flow.

Abstract: The present invention relates to a method for use in liquid scintillation measurements to feed an accurately determined amount of radioactive substance to a fluid scintillation system for a calibration measurement. According to the invention an accurately determined amount of radioactive substance is adsorbed to a carrier, which is introduced into the fluid scintillation system. The invention also relates to a carrier for use in the method.