Experimental Determination of the Topological Phase Diagram in Cerium Monopnictides.

Experimental determinations of bulk band topology in the solid states have been so far restricted to only indirect investigation through the probing of surface states predicted by electronic structure calculations. We here present an alternative approach to determine the band topology by means of bulk-sensitive soft x-ray angle-resolved photoemission spectroscopy. We investigate the bulk electronic structures of the series materials, Ce monopnictides (CeP, CeAs, CeSb, and CeBi). By performing a paradigmatic study of the band structures as a function of their spin-orbit coupling, we draw the topological phase diagram and unambiguously reveal the topological phase transition from a trivial to a nontrivial regime in going from CeP to CeBi induced by the band inversion. The underlying mechanism of the phase transition is elucidated in terms of spin-orbit coupling in concert with their semimetallic band structures. Our comprehensive observations provide a new insight into the band topology hidden in the bulk states.

Devil's staircase transition of the electronic structures in CeSb.

Solids with competing interactions often undergo complex phase transitions with a variety of long-periodic modulations. Among such transition, devil's staircase is the most complex phenomenon, and for it, CeSb is the most famous material, where a number of the distinct phases with long-periodic magnetostructures sequentially appear below the Néel temperature. An evolution of the low-energy electronic structure going through the devil's staircase is of special interest, which has, however, been elusive so far despite 40 years of intense research. Here, we use bulk-sensitive angle-resolved photoemission spectroscopy and reveal the devil's staircase transition of the electronic structures. The magnetic reconstruction dramatically alters the band dispersions at each transition. Moreover, we find that the well-defined band picture largely collapses around the Fermi energy under the long-periodic modulation of the transitional phase, while it recovers at the transition into the lowest-temperature ground state. Our data provide the first direct evidence for a significant reorganization of the electronic structures and spectral functions occurring during the devil's staircase.

The association of the subunits of component C3 of hagfish complement is unstable and leads to novel degradation during electrophoresis.

An opsonic molecule that is designated the third component of hagfish complement (HC3), and a fragment of HC3 known as HC3b have recently been identified in the hagfish, Eptatretus burgeri. These proteins were purified from plasma and generated a set of several bands and/or smears during SDS-PAGE under standard, non-reducing conditions. Two-dimensional electrophoretic analysis of the proteins under non-reducing and reducing conditions revealed the breakdown of polypeptides at the site of a thioester bond and the concomitant partial release of a split product, depending on the weak covalent or non-covalent association of polypeptide chains, in a large fraction of molecules of HC3 during SDS-PAGE. Moreover, the heterogeneity of HC3b can be ascribed to the different configurations of subunits. A similar phenomenon was not observed in the case of lamprey C3, even though breakdown of polypeptides at a thioester bond did occur in some molecules.