Half-metallic surfaces in thin-film Ti2MnAl0.5Sn0.5.

Materials exhibiting a high degree of spin polarization in electron transport are in demand for applications in spintronics-an emerging technology utilizing a spin degree of freedom in electronic devices. Room-temperature half-metals are considered ideal candidates, as they behave as an insulator for one spin channel and as a conductor for the other spin channel. In addition, for nano-size devices, one has to take into account possible modification of electronic structure in thin-film geometry, due to the potential presence of surface/interface states. It has been shown that typically these states have a detrimental impact on half-metallicity, i.e. their presence results in reduced spin-polarization. Here, we employ density functional calculations to explore an inverse Heusler compound, Ti2MnAl0.5Sn0.5, which exhibits half-metallic electronic structure in bulk geometry. In particular, this material behaves as a regular metal for majority-spin, and as a semiconductor for minority-spin states. We show that in thin-film geometry, the type of termination surface has a decisive effect on half-metallicity of this material. In particular, we analyze six possible termination configurations, and show that for four of them, energy states emerge in the minority-spin band gap, significantly reducing the spin polarization of Ti2MnAl0.5Sn0.5. At the same time, our calculations indicate that two termination surfaces preserve half-metallic properties of this material. This result is somewhat unexpected, as most of the available literature reports reduction of the spin-polarization due to the presence of surface states. Thus, our results show that a judicious choice of the termination surface may be a crucial factor in nano-device applications, where highly spin-polarized current is needed.

Mining FDA resources to compute population-specific frequencies of adverse drug reactions.

Adverse drug reactions (ADRs) represent one of the main health and economic problems in the world. With increasing data on ADRs, there is an increased need for software tools capable of organizing and storing the information on drug-ADR associations in a form that is easy to use and understand. Here we present a step by step computational procedure capable of extracting drug-ADR frequency data from the large collection of patient safety reports stored in the Federal Drug Administration database. Our procedure is the first of its type capable of generating population specific drug-ADR frequencies. The drug-ADR data generated by our method can be made specific to a single patient population group (such as gender or age) or a single therapy characteristic (such as drug dosage, duration of therapy) or any combination of such.