Abstract: To determine a coefficient of diffusion of a radioisotope in a radioisotope-containing implant structure and to calculate a quantity of radioisotope to be introduced in an implant structure in view of administering to a vascular region of a patient's body a dose of radioactivity at a given dose rate, a relation is calculated between a coefficient of diffusion of the radioisotope in the implant structure and a coefficient of diffusion of the radioisotope in the vascular region of the patient's body for at least one given period of time during which the radioisotope has to be released. The diffusion coefficient of the vascular region is determined. The method also determines, from the diffusion coefficient of the vascular region and in connection with the above relation, the diffusion coefficient of the implant structure required to release the radioisotope within the given period of time.

Abstract: The invention is concerned with a substantially nitrogen-free process for chloride-route TiO.sub.2 pigment manufacture in which a TiO.sub.2 -containing feedstock is subjected to a fluidized-bed, high temperature carbochlorination in a chlorinator to produce TiCl.sub.4 which is thereafter converted to TiO.sub.2 by oxidation. The TiO.sub.2 -containing feedstock and a solid carbonaceous reducing agent are fed to the chlorinator under a CO.sub.2 blanketing atmosphere such that the carbochlorination is carried out in a substantially nitrogen-free atmosphere containing CO.sub.2 and a CO.sub.2 -rich flue gas is generated, the CO.sub.2 in the chlorinator assisting in controlling thermal balance of the carbochlorination reaction. The absence of significant concentrations of nitrogen in the flue gas results in a favorable condition enabling either or both the CO and CO.sub.2 contained in the flue gas to be readily recovered, purified and sold as by-products.

Abstract: A self-lubricating fuel composition is provided formed from powdered coal, a hydrocarbon fraction, water, a surfactant and a strong electrolyte. This composition develops a lubricating layer between the mechanical parts in relative movement with respect to the fluid and the fluid. Such self lubrication causes a reduction of the friction and consequently of the pressure losses during transport in ducts.