Abstract: The invention intends to measure true distribution of a radioactive nuclide in respective parts of a subject. A density of each part of a subject sample is measured by measuring the intensity of ionizing radiation for density measurement from a radioactive nuclide for density measurement, which emits the ionizing radiation to each part of the subject sample in the same amount, through the subject sample interposed midway, the intensity of ionizing radiation emitted from another radioactive nuclide existing in each part of the subject sample is measured, and the amount of another radioactive nuclide in each part of the subject sample is determined by compensating the measured intensity of the ionizing radiation from another radioactive nuclide based on the self-absorptivity of each part of the subject sample corresponding to the density thereof.

Abstract: A method and apparatus for determining .beta.-ray emitters to determine radioactivity of tritium with a high sensitivity and without contamination of a radiation recording plate with radioactivity, wherein a plastic microplate is provided having a number of flat bottomed wells interconnected by a plurality of shallow vent channels having a depth ranging from about 2 mm to 6 mm formed therein. The radiation recording plate is disposed facing tile microplate through a spacer. A metal exposure container which is sealed accommodates the resulting assembly of the microplate, spacer and the radiation recording plate.

Abstract: A solid strong acid catalyst useful for hydrocarbon reactions, especially for the skeletal isomerization of paraffinic hydrocarbons is provided by supporting sulfate (SO.sub.4) and at least one member selected from Group VIII metals on a support consisting of hydroxides and oxides of Group IV metals and Group III metals and mixtures thereof and then calcining and stabilizing the catalyst.

Abstract: A solid strong acid catalyst useful for hydrocarbon reactions, especially for the skeletal isomerization of paraffinic hydrocarbons is provided by supporting sulfate (SO.sub.4) and at least one member selected from Group VIII metals on a support consisting of hydroxides and oxides of Group IV metals and Group III metals and mixtures thereof and then calcining and stabilizing the catalyst.

Abstract: A synchronized accumulating radiodetector comprises a series of longitudinally connected counting tubes of equal inner volume, a plurality of switching units adapted to be synchronized with the flow speed of radioactive substance traveling with reference to the counting tubes, and a plurality of counting accumulators for counting the radioactivity and accumulate number of the radioactivity. The radiodetector has an accumulated counting output mechanism, from which output is sent to auxiliary recording or displaying unit.

Abstract: A combustion tube for preparing samples for analysis of pollution materials, such as mercury and lead, or isotopes such as tritium and carbon 14, having at least one group of oxygen-supplying tubes disposed downstream in the tube relative to an organic sample and the direction of the oxygen flow. The combustion tube is surrounded by coiled heating wire to heat the interior of the tube to cause combustion of the sample. A gas inlet is provided upstream of the sample for the injection of oxygen, nitrogen, or the like, and a gas outlet is provided at the extreme downstream end of the tube for the exhaustion of gases contained in the tube. Complete combustion of the sample is assured by providing capillary apertures in the oxygen-supplying tubes for the oxygen to exit therefrom in a fine stream.