Stability of the monoclinic phase in the ferroelectric perovskite PbZr(1-x)TixO3

Recent structural studies of ferroelectric PbZr(1-x)TixO3 (PZT) with x= 0.48, have revealed a new monoclinic phase in the vicinity of the morphotropic phase boundary (MPB), previously regarded as the the boundary separating the rhombohedral and tetragonal regions of the PZT phase diagram. In the present paper, the stability region of all three phases has been established from high resolution synchrotron x-ray powder diffraction measurements on a series of highly homogeneous samples with 0.42 <=x<= 0.52. At 20K the monoclinic phase is stable in the range 0.46 <=x<= 0.51, and this range narrows as the temperature is increased. A first-order phase transition from tetragonal to rhombohedral symmetry is observed only for x= 0.45. The MPB, therefore, corresponds not to the tetragonal-rhombohedral phase boundary, but instead to the boundary between the tetragonal and monoclinic phases for 0.46 <=x<= 0.51. This result provides important insight into the close relationship between the monoclinic phase and the striking piezoelectric properties of PZT; in particular, investigations of poled samples have shown that the monoclinic distortion is the origin of the unusually high piezoelectric response of PZT.Comment: REVTeX file, 7 figures embedde

SARM: a novel Toll-like receptor adaptor, is functionally conserved from arthropod to human

10.1016/j.molimm.2007.09.030Molecular Immunology4561732-1742IMCH

Novel Two-Stage Analytic Approach in Extraction of Strong Herb-Herb Interactions in TCM Clinical Treatment of Insomnia

2nd International Conference on Medical Biometrics, ICMB 2010, Hong Kong, China, Jun 28-30, 2010In this paper, we aim to investigate strong herb-herb interactions in TCM for effective treatment of insomnia. Given that extraction of herb interactions is quite similar to gene epistasis study due to non-linear interactions among their study factors, we propose to apply Multifactor Dimensionality Reduction (MDR) that has shown useful in discovering hidden interaction patterns in biomedical domains. However, MDR suffers from high computational overhead incurred in its exhaustive enumeration of factors combinations in its processing. To address this drawback, we introduce a two-stage analytical approach which first uses hierarchical core sub-network analysis to pre-select the subset of herbs that have high probability in participating in herb-herb interactions, which is followed by applying MDR to detect strong attribute interactions in the pre-selected subset. Experimental evaluation confirms that this approach is able to detect effective high order herb-herb interaction models in high dimensional TCM insomnia dataset that also has high predictive accuracies.Department of Health Technology and InformaticsRefereed conference pape