Determination of spin polarization in InAs/GaAs self-assembled quantum dots

The spin polarization of electrons trapped in InAs self-assembled quantum dot ensembles is investigated. A statistical approach for the population of the spin levels allows one to infer the spin polarization from the measure values of the addition energies. From the magneto-capacitance spectroscopy data, the authors found a fully polarized ensemble of electronic spins above 10 T when $\mathbf{B}\parallel[001]$ and at 2.8 K. Finally, by including the g-tensor anisotropy the angular dependence of spin polarization with the magnetic field $\mathbf{B}$ orientation and strength could be determined.Comment: 3 pages, 2 figures, Accepted Appl. Phys. Let

Accurate Determination of Conformational Transitions in Oligomeric Membrane Proteins

The structural dynamics governing collective motions in oligomeric membrane proteins play key roles in vital biomolecular processes at cellular membranes. In this study, we present a structural refinement approach that combines solid-state NMR experiments and molecular simulations to accurately describe concerted conformational transitions identifying the overall structural, dynamical, and topological states of oligomeric membrane proteins. The accuracy of the structural ensembles generated with this method is shown to reach the statistical error limit, and is further demonstrated by correctly reproducing orthogonal NMR data. We demonstrate the accuracy of this approach by characterising the pentameric state of phospholamban, a key player in the regulation of calcium uptake in the sarcoplasmic reticulum, and by probing its dynamical activation upon phosphorylation. Our results underline the importance of using an ensemble approach to characterise the conformational transitions that are often responsible for the biological function of oligomeric membrane protein states