Recurrent reversible in-stent-stenosis after flow diverter treatment

Flow diverter stents (FDS) are well established in the treatment of intracranial aneurysms which are difcult to treat with conventional endovascular techniques. However, they carry a relatively high risk of specifc complications compared to conventional stents. A minor but frequent fnding is the occurrence of reversible in-stent-stenosis (ISS) that tend to resolve spontaneously over time. Here, we report the case of a patient in their 30s who was treated with FDS for bilateral paraophthalmic internal carotid artery (ICA) aneurysms. ISS were found at the respective early follow-up examinations on both sides and had resolved at the 1-year follow-up examinations. Surprisingly ISS reoccurred at both sides in later follow-up examinations and again resolved spontaneously. The recurrence of ISS after resolution is a fnding that has not been described previously. Its incidence and further development should be investigated systematically. This might contribute to our understanding of the mechanisms underlying the efect of FDS

First principles calculations on structure, bonding, and vibrational frequencies of SiPsub 2

Pyrite type SiP2 is reinvestigated by first principles calculations on various levels of functionals including local density approximation, generalized gradient approximation, Becke-Lee-Yang-Parr hybrid functional, and the Hartree-Fock method. SiP2 is seen as a model compound with molecular [P–P] entities and [SiP6] octahedra. Structure and bonding are addressed by electronic structure calculations. Special attention is spent on P–P and Si–P bonds in terms of bond lengths and respective stretching modes from simulated Raman spectra. The electronic structure is analyzed in both direct and momentum space by the electron localization function and site projected density of states. The main goals of this work are to understand the nature of chemical bonding in SiP2 and to compare and contrast the different methods of calculation

Origin and effect of In–Sn ordering in InSnCo3S2: a neutron diffraction and DFT study

The solid solution In2−xSnxCo3S2 is attractive due to a variety of interesting properties depending on the In/Sn content, i.e. half metal ferromagnetic Sn2Co3S2, low dimensional metal In2Co3S2, and semiconducting thermoelectric InSnCo3S2. For the latter, crystal structure effects and a metal to insulator transition are not only related to electron counting but also to ordering of In and Sn within and between Co Kagomé nets. These observations have not been adequately understood to date. The degree of ordering is now evaluated from neutron diffraction data to distinguish In and Sn. The origin and effects on crystal and electronic structures are studied by DFT calculations on a superstructure model. Relations of local bonding (electron localization function ELF and Bader's AIM theory), In/Sn site preference, crystal structure distortions, and the opening of the gap are explored. Results are generalised from predictions on isoelectronic compounds