By human sensory analyses, we found that various extracellular calcium-sensing receptor (CaSR) agonists enhance sweet, salty, and umami tastes, although they have no taste themselves. These characteristics are known as "kokumi taste" and often appear in traditional Japanese cuisine. Although GSH is a typical kokumi taste substance (taste enhancer), its mode of action is poorly understood. Here, we demonstrate how the kokumi taste is enhanced by the CaSR, a close relative of the class C G-protein-coupled receptors T1R1, T1R2, and T1R3 (sweet and umami receptors). We identified a large number of CaSR agonist ␥-glutamyl peptides, including GSH (␥-Glu-Cys-Gly) and ␥-Glu-Val-Gly, and showed that these peptides elicit the kokumi taste. Further analyses revealed that some known CaSR agonists such as Ca 2؉ , protamine, polylysine, L-histidine, and cinacalcet (a calcium-mimetic drug) also elicit the kokumi taste and that the CaSR-specific antagonist, NPS-2143, significantly suppresses the kokumi taste. This is the first report indicating a distinct function of the CaSR in human taste perception.

We report a novel phenomenon intimately related to the spin-triplet superconductivity. It is well known that the spin susceptibility decreases below the superconducting transition temperature in almost all superconductors because of spin-singlet pair formation, while it may remain unchanged in a handful of spin-triplet exceptions. Here we report the observation in Sr2RuO4 with nuclear magnetic resonance (NMR) that the spin susceptibility originating from the Ru-4d electron slightly increases by ∼ 2% of total and becomes inhomogeneous in the superconducting state. These are reasonably explained if the electron pairs form the equal-spin-pairing (ESP) in the mixed state. A similar phenomenon was predicted for superfluid 3 He forty years ago, but had never been demonstrated in any superconductor. Ru [5,6] nuclei are unchanged in the SC state. The unchanged spin susceptibility, which was supported also from the polarized neutron scattering measurements [7], strongly suggests that the equal-spin-pairing (ESP) state of the spin-triplet superconductivity is realized in SRO, in which the SC pairs consist of the up-up (| ↑↑ ) or down-down (| ↓↓ ) pairs. In addition, the µSR [8] and Kerr-effect [9] measurements in the SC state suggest the broken time-reversal symmetry. Unlike heavy-fermion systems, the effect of spin-orbit coupling should be relatively weak, the pairing state in SRO would be closely analogous to the case of superfluid 3 He. By taking the experimental results into account, the chiral p-wave spin-triplet state, which is analogous to the A-phase of superfluid 3 He [10], has been considered as the most promising candidate for the SC pairing state [11,12].However, toward the establishment of this pairing state, there still remains a controversy since the superconductivity is strongly suppressed with a first-order transition under the in-plane magnetic fields near the SC critical field H c2 as shown in Fig. 1 (a) [13,14]. In addition, sharp magnetization jump with the hysteresis at H c2 was observed when the magnetic field is exactly parallel to the ab plane at 0.1 K [15]. These are phenomena usually expected in a spin-singlet superconductor [16,17]. Furthermore, non-detection of some of the behaviors expected for the chiral p-wave state (e.g. chiral edge current [18][19][20] and splitting of T c by in-plane magnetic fields of any magnitude [21]) casts some doubts on this pairing state. Therefore, convincing evidence for establishing the SC pairing state in SRO, particularly finding a new phenomenon specific to the pairing state, has been desired.In this paper, we report, from the "double-site" Knight-shift measurement in the SC state, which is the reliable method to subtract the Meissner effect from the observed Knight shift, that the spin susceptibility of SRO becomes inhomogeneous and its average slightly increases in the SC state. The small increase of spin susceptibility cannot be explained with a singlet-pairing state but consistently interpreted with the ESP state in triplet superconductivity. As far as ...

We conducted77 Se-nuclear magnetic resonance studies of the iron-based superconductor FeSe in magnetic fields of 0.6 to 19 T to investigate the superconducting and normal-state properties. The nuclear spin-lattice relaxation rate divided by the temperature (T1T ) −1 increases below the structural transition temperature Ts but starts to be suppressed below T * , well above the superconducting transition temperature Tc(H), resulting in a broad maximum of (T1T ) −1 at Tp(H). This is similar to the pseudogap behavior in optimally doped cuprate superconductors. Because T * and Tp(H) decrease in the same manner as Tc(H) with increasing H, the pseudogap behavior in FeSe is ascribed to superconducting fluctuations, which presumably originate from the theoretically predicted preformed pair above Tc(H).The discovery of superconductivity in iron pnictide 1)provided new research systems in which the unconventional superconductivity realized in strongly correlated electron compounds can be studied. Among the Fe-based superconductors (FeSCs), FeSe, which exhibits superconductivity at T c ∼ 9 K, has the simplest crystalline structure, which is called the 11 structure,2) but it exhibits several properties unlike those of other FeSCs. A tetragonal-to-orthorhombic structural transition occurs at T s ∼ 90 K without long-range antiferromagnetic (AFM) ordering down to T c .3) This is in stark contrast with the other FeSCs, such as the 122 and 1111 systems, where static AFM ordering was observed at or slightly below T s . 4,5) We reported that the 77 Se nuclear magnetic resonance (NMR) spectrum splits below T s and that the nuclear spin-lattice relaxation rate divided by T , (T 1 T ) −1 , of 77 Se is enhanced below T s . 6) These results suggest that orbital ordering induces the electronic nematic state below T s and also triggers the development of AFM fluctuations with stripe correlations breaking the C 4 symmetry in FeSe.6, 7) This scenario is consistent with the results of angle-resolved photoemission spectroscopy, 8,9) but it seems to be inconsistent with the AFM-fluctuation-driven nematic scenario.10) In any case, FeSe is an ideal system for studying the origin of the electronic nematic state in FeSCs.It was recently suggested that the superconductivity in FeSe may be in the Bardeen-Cooper-Schrieffer (BCS)-Bose-Einstein condensate (BEC) crossover regime, as an extremely small Fermi energy comparable to the superconducting (SC) condensation energy was revealed by several measurements.11, 12) In a schematic phase diagram of the attractive Hubbard model, the interaction between two fermions (e.g., electrons in solids) is in the weak-coupling regime in the BCS state and in the strongcoupling regime in the BEC state. The characteristic pa-

We have studied the superlattices with alternating block layers (BLs) of heavy-fermion superconductor CeCoIn5 and conventional-metal YbCoIn5 by site-selective nuclear magnetic resonance(NMR) spectroscopy, which uniquely offers spatially-resolved dynamical magnetic information. We find that the presence of antiferromagnetic fluctuations is confined to the Ce-BLs, indicating that magnetic degrees of freedom of f -electrons are quenched inside the Yb-BLs. Contrary to simple expectations that the two-dimensionalization enhances fluctuations, we observe that antiferromagnetic fluctuations are rapidly suppressed with decreasing Ce-BL thickness. Moreover, the suppression is more prominent near the interfaces between the BLs. These results imply significant effects of local inversion-symmetry breaking at the interfaces.

Topological insulators (TIs) are expected to realize new spintronic devices with low dissipative electrical transport. Organic molecule/TI interfaces have been investigated to explore the potential of multifunctional organic molecules for TI devices. However, there is no unified understanding of the interfacial electronic structure. The electronic structure of the molecular side must be examined to fully understand the phenomena at the interface. Thus, this paper reports the investigation of the interface between the electron‐donating organic molecule tetrathianaphthacene (TTN) and prototypical TI Bi2Se3 by ultraviolet photoemission spectroscopy (UPS), X‐ray photoemission spectroscopy (XPS), and angle‐resolved photoemission spectroscopy (ARPES). The deformation of the Fermi surface of the topological surface states as well as the formation of a 2D electron gas state (2DEG) at the interface occurs upon TTN deposition onto Bi2Se3. Confinement of the 2DEG into the surface arises from band‐bending accompanied by electron donation from TTNs to Bi2Se3 according to XPS and UPS. The knowledge obtained in this work shed new light on the understanding of the electronic structure of organic molecules/TI interfaces and open the door to the TI applications via modification by electronic functional organic molecules.