Strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.

The degradation of the organic electroluminescent (EL) device is closely related to the physical and chemical stability of the organic thin films. Three important aspects are described: 1) an effect of glass transition temperature of hole transport materials on thermal stability of the device; 2) a role of interface layers at both the anode and cathode; and 3) an improvement of operation stability by doping technology. Considering the above points, an organic EL device was fabricated with a good operation performance: lifetime of longer than 3000 h at an initial luminance of 500 cd/m 2 .

SYNOPSISImpact modification was studied for a variety of engineering thermoplastics to determine if notched Izod data obtained at various temperatures and modifier concentrations could be correlated with particle size or surface-to-surface interparticle distance of the modifier. Elastomers evaluated were characteristic of those used in commercial blend systems for those polymers, and both functionalized and nonfunctionalized materials were studied. For the single matrix polymer/elastomer-modified blend systems studied [ poly (phenylene sulfide) (PPS) , polyoxymethylene (POM) , poly( butylene terephthalate) (PBT) 1, elastomer interparticle distance provides a better correlation to brittle-tough transition temperature than does particle size, as predicted by the Wu model. In POM, the dispersion morphology of the samples used was not adequate to achieve the critical interparticle distance required for supertoughening a t room temperature. In this study, the critical interparticle distance has been shown to depend on the degree of crystallinity (PPS) and the modulus of the impact modifier relative to the matrix (PBT) . Actual adhesion of the polymer to the matrix (variation of functionality levels) was not found to have a strong influence (PBT). In POM, the increase in impact at the brittle-tough transition was dependent on the molecular weight of the base resin. This is examined with respect to the ratio of the molecular weight ( M , ) to the entanglement molecular weight ( M e ) , which determines the critical molecular weight necessary to achieve useful physical properties. In polyester (PET) /polycarbonate (PC)/elastomer blends, the molecular weight of the primary matrix resin (PET) determined impact properties within the molecular weight range of the resin studied. This was again related to the M J M , ratio for PET and PC.

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