Experimental and theoretical study of rhenium radioisotopes production for manufacturing of new compositional radiopharmaceuticals.

Rhenium therapeutic radioisotopes, namely rhenium-186 and 188, are radionuclides that have been used in combination with various ligands to provide different radiopharmaceuticals for the treatment of different diseases for many years. Each of these radioisotopes has its own special attributes, which make it appropriate to destroy special-sized tumors. High energy, long range beta particles in 188Re can give this certainty that large tumors can be eradicated with high efficiency. On the other hand, 186Re with low energy, short range beta particles is adequate item to ruin small tumors with minimum side effects and high yield. Thus, each of these radioisotopes has features that can cover just part of the treatment individually. So we thought accompanying 186Re and 188Re must have the best outcome to treat tumors with various sizes. Irradiating natural rhenium with neutrons has this potential to produce parallel 186Re and 188R together. We are looking for investigating whether the natural rhenium irradiation, in addition the concurrent production of these radioisotopes, gives us the appropriate radioactivity values to produce compositional radiopharmaceuticals? In this research, the experimental and theoretical assessments of 186Re and 188R simultaneous production to reach compositional radiopharmaceutical by natural rhenium irradiation in the Tehran research reactor, as well as the type and amount of produced impurities have been investigated. The results showed that experimental data are in good agreement with theoretical calculations. The maximum relative error in data has been calculated 8%. The results showed that, in the simultaneous production 186Re and 188R via the natural rhenium irradiation method, the amounts of impurities are trivial compared to the main products, and the activities of main products are properly enough to produce compositional radiopharmaceuticals.

Stiffer double-stranded DNA in two-dimensional confinement due to bending anisotropy.

Using analytical approach and Monte Carlo (MC) simulations, we study the elastic behavior of the intrinsically twisted elastic ribbons with bending anisotropy, such as double-stranded DNA (dsDNA), in two-dimensional (2D) confinement. We show that, due to the bending anisotropy, the persistence length of dsDNA in 2D conformations is always greater than three-dimensional (3D) conformations. This result is in consistence with the measured values for DNA persistence length in 2D and 3D in equal biological conditions. We also show that in two dimensions, an anisotropic, intrinsically twisted polymer exhibits an implicit twist-bend coupling, which leads to the transient curvature increasing with a half helical turn periodicity along the bent polymer.