Flat bands promoted by Hund's rule coupling in the candidate double-layer high-temperature superconductor La3_3Ni2_2O7_7

We report strongly correlated electronic band structure calculations of the recently discovered double-layer high-temperature superconductor La$_3$Ni$_2$O$_7$ under pressure. Our calculations reveal dual nature of Ni-$d$ electrons with almost localized $d_{z^2}$ orbitals due to onsite Coulomb repulsion and very flat hybridization bands of Ni-$d_{x^2-y^2}$ and Ni-$d_{z^2}$ quasiparticles near the Fermi energy. We find that the quasiparticle effective mass are greatly enhanced by the Hund's rule coupling and their lifetimes are inversely proportional to the temperature, which explains the experimentally observed strange metal behavior in the normal state. We also find strong antiferromagnetic spin correlations of Ni-$d$ electrons, which may provide the pairing force of quasiparticles for the high-temperature superconductivity. These give a potential explanation of two key observations in experiment and connect the superconducting La$_3$Ni$_2$O$_7$ with cuprate high-temperature superconductors. The presence of flat bands and the interplay of orbital-selective Mott, Hund, and Kondo physics make La$_3$Ni$_2$O$_7$ a unique platform for exploring rich emergent quantum many-body phenomena in the future.Comment: 6 pages, 4 figure

Two-Dimensional Halide Perovskites for Emerging New- Generation Photodetectors

Compared to their conventional three-dimensional (3D) counterparts, two-dimensional (2D) halide perovskites have attracted more interests recently in a variety of areas related to optoelectronics because of their unique structural characteristics and enhanced performances. In general, there are two distinct types of 2D halide perovskites. One represents those perovskites with an intrinsic layered crystal structure (i.e. MX6 layers, M = metal and X = Cl, Br, I), the other defines the perovskites with a 2D nanostructured morphology such as nanoplatelets and nanosheets. Recent studies have shown that 2D halide perovskites hold promising potential for the development of new-generation photodetectors, mainly arising from their highly efficient photoluminescence and absorbance, color tunability in the visible-light range and relatively high stability. In this chapter, we present the summary and highlights of latest researches on these two types of 2D halide perovskites for developing photodetectors, with an emphasis on synthesis methods, structural characterization, optoelectronic properties, and theoretical analysis and simulations. We also discuss the current challenging issues and future perspective. We hope this chapter would add new elements for understanding halide perovskite-based 2D materials and for developing their more efficient optoelectronic devices

Anthropomorphism of Intelligent Personal Assistants (IPAs): Antecedents and Consequences

Based on the distinctively anthropomorphic features of intelligent personal assistants (IPAs), this paper proposes a theoretical model to investigate the antecedents and consequences of IPA anthropomorphism based on three-factor theory. Specifically, it is hypothesized that anthropomorphic features of IPAs, which are synthesized speech quality, autonomy, sociability and personality, positively affect IPA anthropomorphism. Meanwhile IPA anthropomorphism influences IPA self-efficacy and social connection positively. IPA self-efficacy and social connection, in turn, are positively related to intention to explore IPAs. Scales will be developed and data will be collected through online survey. Then structural equation model (SEM) will be applied to validate the model

A Weil-Petersson Type Metric on the Space of Fano Kaehler-Ricci Solitons

In this paper we define a Weil-Petersson type metric on the space of shrinking Kaehler-Ricci solitons and prove a necessary and sufficient condition on when it is independent of the choices of Kaehler-Ricci soliton metrics. We also show that the Weil-Petersson metric is Kaehler when it defines a metric on the Kuranishi space of small deformations of Fano Kaehler-Ricci solitons. Finally, we establish the first and second order deformation of Fano K\"ahler-Ricci solitons and show that, essentially, the first effective term in deforming Kaehler-Ricci solitons leads to the Weil-Petersson metric.Comment: 16 pages; final version available at the journal cite of JGEA (see the journal reference info below

Convergence and optimality of an adaptive modified weak Galerkin finite element method

An adaptive modified weak Galerkin method (AmWG) for an elliptic problem is studied in this paper, in addition to its convergence and optimality. The weak Galerkin bilinear form is simplified without the need of the skeletal variable, and the approximation space is chosen as the discontinuous polynomial space as in the discontinuous Galerkin method. Upon a reliable residual-based a posteriori error estimator, an adaptive algorithm is proposed together with its convergence and quasi-optimality proved for the lowest order case. The major tool is to bridge the connection between weak Galerkin method and the Crouzeix-Raviart nonconforming finite element. Unlike the traditional convergence analysis for methods with a discontinuous polynomial approximation space, the convergence of AmWG is penalty parameter free

Genome-wide profiling of gene expression in the epididymis of alpha-chlorohydrin-induced infertile rats using an oligonucleotide microarray

<p>Abstract</p> <p>Background</p> <p>As one of the chlorinated antifertility compounds, alpha-chlorohydrin (ACH) can inhibit glyceraldehyde-3-phosphate dehydrogenase (G3PDH) activity in epididymal sperm and affect sperm energy metabolism, maturation and fertilization, eventually leading to male infertility. Further studies demonstrated that the inhibitory effect of ACH on G3PDH is not only confined to epididymal sperm but also to the epididymis. Moreover, little investigation on gene expression changes in the epididymis after ACH treatment has been conducted. Therefore, gene expression studies may indicate new epididymal targets related to sperm maturation and fertility through the analysis of ACH-treated infertile animals.</p> <p>Methods</p> <p>Rats were treated with ACH for ten consecutive days, and then each male rat copulated with two female rats in proestrus. Then sperm maturation and other fertility parameters were analyzed. Furthermore, we identified epididymal-specific genes that are associated with fertility between control and ACH groups using an Affymetrix Rat 230 2.0 oligo-microarray. Finally, we performed RT-PCR analysis for several differentially expressed genes to validate the alteration in gene expression observed by oligonucleotide microarray.</p> <p>Results</p> <p>Among all the differentially expressed genes, we analyzed and screened the down-regulated genes associated with metabolism processes, which are considered the major targets of ACH action. Simultaneously, the genes that were up-regulated by chlorohydrin were detected. The genes that negatively regulate sperm maturation and fertility include apoptosis and immune-related genes and have not been reported previously. The overall results of PCR analysis for selected genes were consistent with the array data.</p> <p>Conclusions</p> <p>In this study, we have described the genome-wide profiles of gene expression in the epididymides of infertile rats induced by ACH, which could become potential epididymal specific targets for male contraception and infertility treatment.</p