https://www.selleckchem.com/products/bp-1-102.html Two lowest-energy odd-parity atomic levels of actinium, 7s^27p^2P_1/2^o, 7s^27p^2P_3/2^o, were observed via two-step resonant laser-ionization spectroscopy and their respective energies were measured to be 7477.36(4) and 12 276.59(2)  cm^-1. The lifetimes of these states were determined as 668(11) and 255(7) ns, respectively. In addition, we observed the effect of the hyperfine structure on the line for the transition to ^2P_3/2^o. These properties were calculated using a hybrid approach that combines configuration interaction and coupled-cluster methods, in good agreement with the experiment. The data are of relevance for understanding the complex atomic spectra of actinides and for developing efficient laser cooling and ionization schemes for actinium, with possible applications for high-purity medical-isotope production and future fundamental physics experiments.We study the viscous properties of a system of weakly interacting spin-1/2 fermions in one dimension. Accounting for the effect of interactions on the quasiparticle energy spectrum, we obtain the bulk viscosity of this system at low temperatures. Our result is valid for frequencies that are small compared with the rate of fermion backscattering. For frequencies larger than this exponentially small rate, the excitations of the system become decoupled from the center of mass motion, and the fluid is described by two-fluid hydrodynamics. We calculate the three transport coefficients required to describe viscous dissipation in this regime.Eigenstate thermalization is widely accepted as the mechanism behind thermalization in generic isolated quantum systems. Using the example of a single magnetic defect embedded in the integrable spin-1/2 XXZ chain, we show that locally perturbing an integrable system can give rise to eigenstate thermalization. Unique to such setups is the fact that thermodynamic and transport properties of the unperturbed integrable chain eme