Muon spin relaxation study of spin dynamics in poly(triarylamine)

Organic semiconductors (OSCs) have been of great interest over the last couple of decades owing to their mechanic flexibility, ease of processing, high tuneability and availability. One area of OSCs that is of growing interest is polymers as they possess many of the desirable properties, in particular print processing and tunability of electronic properties, necessary for application in devices such as organic solar cells and the spin valves being engineered for hard disks and logic devices. Much focus has been given in recent years to the areas of research including the electron and hole dynamics, transport mechanisms and spin relaxation in OSCs in order to utilise them in novel organic devices. In this paper the µSR technique is applied to carry out an in depth study of the electron dynamics and spin relaxation in the commonly used Poly(triarylamine) polymer (PTAA). It is shown that the electron wavefunction can be considered localised to the aromatic rings providing a strong hyperfine coupling interaction with the muon. In addition the presence of an electron spin relaxation (eSR) is demonstratated that resembles that previously reported in the small organic molecule series

Radiopharmacy/Radiochemistry for Conventional Single-Photon Emitting and Therapeutic Radiopharmaceuticals

Conventional agents for diagnostic single-photon emission imaging and for radionuclide therapy are mostly associated with radiopharmaceuticals labeled with technetium-99m and iodine radioisotopes. This category of radiopharmaceuticals still determines, to a great extent, the usual operations inside a conventional hospital radiopharmacy. Although this description is not universally accepted and can be certainly subjected to some revision, for the purpose of the present chapter, by “conventional radiopharmacy” is meant a laboratory for the preparation and quality control of radiopharmaceuticals that are produced using either commercial, lyophilized kit formulations or supplied as ready-to-use pharmaceutical preparations. It is implicitly assumed that radiopharmaceutical products belonging to this class of licensed drugs have been always approved by some regulatory authority and intended for a specific clinical application. Obviously, radiopharmaceuticals labeled with radionuclides other than technetium-99m or iodine radioisotopes, but that can be obtained through a kit formulation or as ready-to-use preparations, e.g., indium-111 pentetreotide (Octreoscan®), radium-223 chloride (Xofigo®), yttrium-90 ibritumomab tiuxetan (Zevalin®), or rhenium-188 hydroxyethylidene diphosphonate (188Re-HEDP), can be conveniently included into this category. Conversely, both diagnostic single-photon emitting and therapeutic radiopharmaceuticals that are produced in-house following an extemporaneous, unlicensed procedure (galenic or magistral preparations) will not be considered in this chapter. From the point of view of radiopharmacy requirements, this ensemble of radiolabeling reactions is fully equivalent to those employed for preparing tracers for positron emission tomography (PET) using cyclotron-produced radionuclides. In particular, according to still predominant regulations, extemporaneous therapeutic radiopharmaceuticals should be obtained strictly following the rules of good manufacturing practice (GMP)

Thermal Convection in a Ferromagnetic Fluid Layer with Magnetic Field Dependent Viscosity: A Correction Applied

The effect of magnetic field dependent (MFD) viscosity on thermal convection in a horizontal ferromagnetic fluid layer has been investigated numerically. A correction is applied to Sunil et al. [24] which is very important in order to predict the correct behavior of MFD viscosity. Linear stability analysis has been carried out for stationary convection. The MFD viscosity parameter δ as well as the measure of nonlinearity of magnetization M3, both have a stabilizing effect on the system. Numerical results are also obtained for large values of magnetic parameter M1 and predicted graphically