Radioactive, preparation

After the Curies, with the assistance of M. G. Bemont, had carried out many laborious fractionations of barium chloride, they found that the most insoluble fractions were the most radioactive. In the course of her experiments Mme. Curie had learned that radioactivity is an atomic property depending solely on the quantity of active element present." For this reason the presence of another active element was suspected, and the radioactive barium chloride was therefore submitted to M. Demarcay for spectroscopic examination. He detected a new line in the ultraviolet region of the spectrum, and certain other lines, all of which were most distinct in the most radioactive preparations, and, as fractionation proceeded, the barium lines became fainter and fainter (23, 28, 52). 

When the cyclotron bombardment method became available, H. B. Law, M. L. Pool, J. D. Kurbatov, and L. L. Quill at Ohio State University bombarded samples of neodymium and samarium and obtained radioactive preparations which they believed might contain some 61 (18). C. S. Wu and E. Segre confirmed this (19). F. A. Paneth pointed out that they probably actually had obtained 61 in their mixtures, but the cyclotron method was not sufficiently powerful to give conclusive evidence of its existence (10). Nevertheless, the Ohio State group proposed the name cyclonium for the element. 

However, at this stage the results of another area of our research of the benzoylphenyl ureas, i.e. the environmental studies, were going to have a vital influence on the further selection of the best compound. A preliminary study with a radioactive preparation of the "parent" compound Du 191 11> labeled with at the carbonyl group of the benzoyl... 

More detailed studies of the metabolic pathways of diflubenzuron in soils have been carried out with radioactive preparations labeled in four different positions of the molecule for a study of the ultimate fate of the primary degradation products. 

To label DNA radioactively, prepare in vial 1 (ideally a conical screw cap microcentrifiige tube), a mixture of 20pi DNA solution (5pg DNA/pl) and 80pl 0.1 M ammonium acetate buffer, pH 5. To label siRNA, prepare in vial 1, a mixture... 

An important field of application of the theory of deviations is the subject of radioactivity. Here it is a question of counting the number of particles emitted by a radioactive preparation per second (e.g. by means of a Geiger counting apparatus (p. 32)). If we are dealing with a long-lived substance, for which the average number (n) of... 

A radioactively labeled (or "tagged") compound is one in which one of the atoms is radioactive. Preparation of labeled compounds may involve lengthy chemical synthesis starting with the radioactive nuclides in elementary form or in a simple compound. 

Although work in a water analysis laboratory does not involve the more strongly radioactive preparations, and indeed only very low activities are... 

There are very strict limits on the amount of radioactivity that can be administered for each type of investigation to be performed. These limits are set by the legislative bodies in individual countries. Therefore, all radioactive preparations must be checked for activity before administration. Most radionuclide calibrators used in radiopharmacy are ionization chambers. Commercial calibrators have built in scaling factors for individual radionuclides that take into account the ionizing ability of the isotope and give a readout in the appropriate units (kBq or MBq, or mCi). However, this type of calibrator is not ideal for all radionuclides. Low-energy radiation, such as that produced by iodine may be attenuated before... 

Elements with high atomic weights are especially suitable as absorbers for X-rays and gamma radiation. For that reason, lead has an important use as protection against radiation in laboratories and hospitals in which X-ray methods are utilized, and lead protection is used in the nuclear industry. Lead foils are used, for similar reasons, for packing of radioactive preparations and X-ray films. 

Morell et al. (1966) observed that a radioactive preparation of asialoceruloplasmin upon injection into rabbits was cleared from the circulation in a matter of minutes, vastly more rapidly than native ceruloplasmin, whose half-life is about 56 hr. In subsequent work (Morell et al., 1968) they observed that the rapid disappearance of the asialoceruloplasmin from the serum was accompanied by an equally rapid accumulation of radioactivity within the liver, specifically in the lysosomal fraction of the parenchymal cells (Gregoriadis et al., 1970). 

In the most extensively used method the potential is determined between a calomel electrode connected through a salt bridge to the solution and a second electrode in the air just above the solution. This second electrode contains a radioactive preparation, which, by its ionizing radiation, makes the air gap conducting enough to allow a measurement. 

---