Observation of tunneling gap in epitaxial ultrathin films of pyrite-type copper disulfide

We report scanning tunneling microscopy investigation on epitaxial ultrathin films of pyrite-type copper disulfide. Layer by layer growth of CuS2 films with a preferential orientation of (111) on SrTiO3(001) and Bi2Sr2CaCu2O8+{\delta} substrates is achieved by molecular beam epitaxy growth. For ultrathin films on both kinds of substrates, we observed symmetric tunneling gap around Fermi level that persists up to ~ 15 K. The tunneling gap degrades with either increasing temperature or increasing thickness, suggesting new matter states at the extreme two dimensional limit.Comment: 4 Figure

A Penalized Multi-trait Mixed Model for Association Mapping in Pedigree-based GWAS

In genome-wide association studies (GWAS), penalization is an important approach for identifying genetic markers associated with trait while mixed model is successful in accounting for a complicated dependence structure among samples. Therefore, penalized linear mixed model is a tool that combines the advantages of penalization approach and linear mixed model. In this study, a GWAS with multiple highly correlated traits is analyzed. For GWAS with multiple quantitative traits that are highly correlated, the analysis using traits marginally inevitably lose some essential information among multiple traits. We propose a penalized-MTMM, a penalized multivariate linear mixed model that allows both the within-trait and between-trait variance components simultaneously for multiple traits. The proposed penalized-MTMM estimates variance components using an AI-REML method and conducts variable selection and point estimation simultaneously using group MCP and sparse group MCP. Best linear unbiased predictor (BLUP) is used to find predictive values and the Pearson's correlations between predictive values and their corresponding observations are used to evaluate prediction performance. Both prediction and selection performance of the proposed approach and its comparison with the uni-trait penalized-LMM are evaluated through simulation studies. We apply the proposed approach to a GWAS data from Genetic Analysis Workshop (GAW) 18

Sputtered highly ordered TiO2 nanorod arrays and their applications as the electrode in dye-sensitized solar cells

For the first time, the TiO2 nanorod arrays have been prepared on ITO substrates at room temperature by dc reactive magnetron sputtering technique. These TiO2 nanorods have a preferred orientation along the (220) direction and are perpendicular to the ITO substrate. Both the X-ray diffraction and Raman scattering measurements show that the highly ordered TiO2 nanorod arrays have an anatase crystal structure. The diameter of the nanorod varies from 30 nm to 100 nm and the nanorod length can be varied from several hundred nanometers to several micrometers depending on the deposition time. The TiO2 nanorod arrays with about 3 micrometers length have been used as an electrode for dye-sensitized solar cell (DSSC). Short-circuit photocurrent density, open-circuit voltage, fill factor and light-to-electricity conversion efficiency at 100 mW/cm2 light intensity are estimated to be 12.76 mA/cm2, 0.65 V, 0.63 and 5.25%, respectively, for the DSSC made of the TiO2 nanorods.SFRH/BSAB/862/2008, FC