The Ch/Cr ratio by MRS could effectively predict the tumor subtype and was significantly correlated with the expression of SSTR2, which was consistent with other predictors. It was also able to distinguish the patients with isointense T2 signals. Our results provide a potentially new and non-invasive method to predict the response to SSAs in patients with GH pituitary macroadenomas.

Ferroelectric tungsten-based Aurivillius oxides are naturally stable superlattice structures, in which A-site deficient perovskite blocks [WnO3n+1] −2 (n = 1, 2, 3, ...) interleave with fluorite-like bismuth oxide layers [Bi2O2] +2 along the c-axis. In the n = 2 Bi2W2O9 phase, an in-plane antipolar distortion dominates but there has been controversy as to the ground state symmetry. Here we show, using a combination of first-principles density functional theory calculations and experiments, that the ground state is a non-polar phase of P nab symmetry. We explore the energetics of metastable phases and the potential for antiferroelectricity in this n = 2 Aurivillius phase. arXiv:2003.00486v1 [cond-mat.mtrl-sci]