Structure versus relaxor properties in Aurivillius type compounds

International audienceStructure refinements inMIIBi4Ti4O15 (MII = Ca, Ba), Bi4−xBaxTi3−xNbxO12, (Na0.5Bi0.5)1−xBaxBi4Ti4O15 and Bi4Ti3O12–PbTiO3 systems are used to report structural features of relaxor Aurivillius phases. In compounds with relaxor-like behaviour, the average structure is almost undistorted, closed to the archetypal HT paraelectric phase, with a tolerance factor 0.996. The coordination number of Bi3+ in fluorite layers changes from {4+2} for ferroelectrics to {4} for relaxors. Transmission Electron Microscopy reveals some characteristic features of relaxors such as micro-twinning, shearing-type defects which attest from the existence of a compositional inhomogeneity and a disorder at a local scale

Structural evolution in three and four-layer Aurivillius solid solutions: A comparative study versus relaxor properties

International audienceTwo solid solutions of three-layer BaxBi4xNbxTi3xO12 (0 x 1.2) and four-layer Aurivillius compounds (Na0.5Bi0.5)1xBaxBi4Ti4O15 (0 x 1), which both present a ferroelectric to relaxor-like transition with increasing x, were synthesized by solid state reaction. The evolution of their crystal structures, as a function of x, was performed using Rietveld refinements from X-ray powder diffraction data. As x increases, the average crystal structures become less distorted with respect to the archetypal high temperature tetragonal one and the coordination number of Bi3þ in M2O2 layers continuously changes from {4 þ 2} to {4}. The relaxor behaviour which appears in samples for a tolerance factor t > 0.96 is associated with a general static disorder in A and M sites together with the presence of some Ba2þ cations in M2O2 layers (less than 10%)

Thymic Stromal Lymphopoietin Induction Suppresses Lung Cancer Development

Lung cancer is the leading cause of cancer deaths in the United States and across the world. Immunotherapies, which activate tumor-infiltrating cytotoxic T lymphocytes, have demonstrated efficacy for the treatment of advanced-stage lung cancer. However, the potential for harnessing the immune system against the early stages of lung carcinogenesis to prevent cancer development and recurrence remains unexplored. Using a mouse model of lung adenocarcinoma, we investigated the effects of thymic stromal lymphopoietin (TSLP) induction on early cancer development in the lungs. Herein, we demonstrate that systemic TSLP induction suppressed spontaneous lung cancer development in KrasG12D mice. TSLP drove a significant CD4+ T cell response to block lung cancer progression from atypical alveolar hyperplasia to adenocarcinoma. Our findings suggest that TSLP can be used in the early stages of lung cancer development to trigger a lasting immunity in the tissue and prevent the development of advanced disease