Unified electronic phase diagram for hole-doped high-Tc cuprates

We have analyzed various characteristic temperatures and energies of hole-doped high-Tc cuprates as a function of a dimensionless hole-doping concentration (pu). Entirely based on the experimental grounds we construct a unified electronic phase diagram (UEPD), where three characteristic temperatures (T*'s) and their corresponding energies (E*'s) converge as pu increases in the underdoped regime. T*'s and E*'s merge together with the Tc curve and 3.5kBTc curve at pu - 1.1 in the overdoped regime, respectively. They finally go to zero at pu - 1.3. The UEPD follows an asymmetric half-dome-shaped Tc curve in which Tc appears at pu - 0.4, reaches a maximum at pu - 1, and rapidly goes to zero at pu - 1.3. The asymmetric half-dome-shaped Tc curve is at odds with the well-known symmetric superconducting dome for La2-xSrxCuO4 (SrD-La214), in which two characteristic temperatures and energies converge as pu increases and merge together at pu - 1.6, where Tc goes to zero. The UEPD clearly shows that pseudogap phase precedes and coexists with high temperature superconductivity in the underdoped and overdoped regimes, respectively. It is also clearly seen that the upper limit of high-Tc cuprate physics ends at a hole concentration that equals to 1.3 times the optimal doping concentration for almost all high-Tc cuprate materials, and 1.6 times the optimal doping concentration for the SrD-La214. Our analysis strongly suggests that pseudogap is a precursor of high-Tc superconductivity, the observed quantum critical point inside the superconducting dome may be related to the end point of UEPD, and the normal state of the underdoped and overdoped high temperature superconductors cannot be regarded as a conventional Fermi liquid phase.Comment: 17 pages, 8 figures, and 10 tables. Accepted for the publication of the Physical review

Planar hole-doping concentration and effective three-dimensional hole-doping concentration for single-layer high-TcT_c superconductors

We propose that physical properties for the high temperature superconductors can be addressed by either a two-dimensional planar hole-doping concentration ($P_{pl}$) or an effective three-dimentional hole-doping concentration ($P_{3D}$). We find that superconducting transition temperature ($T_c$) exhibits a universal dome-shaped behavior in the $T_c$ $vs.$ $P_{3D}$ plot with a universal optimal doping concentration at $P_{3D}$ $\sim$ 1.6 $\times$ 10$^{21}$ cm$^{-3}$ for the single-layer high temperature superconductors.Comment: 2pages, 2 figures, submitted to Physica C (Proceedings of M2S-HTSC VIII) ; Ref. 10 is revise

VLBI Astrometry of the Semiregular Variable RX Bootis

We present distance measurement of the semiregular variable RX Bootis (RX Boo) with its annual parallax. Using the unique dual-beam system of the VLBI Exploration of Radio Astrometry (VERA) telescope, we conducted astrometric observations of a water maser spot accompanying RX Boo referred to the quasar J1419+2706 separated by 1.69 degrees from RX Boo. We have measured the annual parallax of RX Boo to be 7.31 +/- 0.50 mas, corresponding to a distance of 136 +10/-9 pc, from the one-year monitoring observation data of one maser spot at VLSR = 3.2 km/s. The distance itself is consistent with the one obtained with Hipparcos. The distance uncertainty is reduced by a factor of two, allowing us to determine the stellar properties more accurately. Using our distance, we discuss the location of RX Boo in various sequences of Period-Luminosity (PL) relations. We found RX Boo is located in the Mira sequence of PL relation. In addition, we calculated the radius of photosphere and the mass limitation of RX Boo and discussed its evolutionary status.Comment: 8 pages, 4figure

A prospective compound screening contest identified broader inhibitors for Sirtuin 1

Potential inhibitors of a target biomolecule, NAD-dependent deacetylase Sirtuin 1, were identified by a contest-based approach, in which participants were asked to propose a prioritized list of 400 compounds from a designated compound library containing 2.5 million compounds using in silico methods and scoring. Our aim was to identify target enzyme inhibitors and to benchmark computer-aided drug discovery methods under the same experimental conditions. Collecting compound lists derived from various methods is advantageous for aggregating compounds with structurally diversified properties compared with the use of a single method. The inhibitory action on Sirtuin 1 of approximately half of the proposed compounds was experimentally accessed. Ultimately, seven structurally diverse compounds were identified