Competing electronic orders on Kagome lattices at van Hove filling

The electronic orders in Hubbard models on a Kagome lattice at van Hove filling are of intense current interest and debate. We study this issue using the singular-mode functional renormalization group theory. We discover a rich variety of electronic instabilities under short range interactions. With increasing on-site repulsion $U$, the system develops successively ferromagnetism, intra unit-cell antiferromagnetism, and charge bond order. With nearest-neighbor Coulomb interaction $V$ alone (U=0), the system develops intra-unit-cell charge density wave order for small $V$, s-wave superconductivity for moderate $V$, and the charge density wave order appears again for even larger $V$. With both $U$ and $V$, we also find spin bond order and chiral $d_{x^2 - y^2} + i d_{xy}$ superconductivity in some particular regimes of the phase diagram. We find that the s-wave superconductivity is a result of charge density wave fluctuations and the squared logarithmic divergence in the pairing susceptibility. On the other hand, the d-wave superconductivity follows from bond order fluctuations that avoid the matrix element effect. The phase diagram is vastly different from that in honeycomb lattices because of the geometrical frustration in the Kagome lattice.Comment: 8 pages with 9 color figure

Theory of high energy features in angle-resolved photo-emission spectra of hole-doped cuprates

The recent angle-resolved photoemission measurements performed up to binding energies of the order of 1eV reveals a very robust feature: the nodal quasi-particle dispersion breaks up around 0.3-0.4eV and reappears around 0.6-0.8eV. The intensity map in the energy-momentum space shows a waterfall like feature between these two energy scales. We argue and numerically demonstrate that these experimental features follow naturally from the strong correlation effects built in the familiar t-J model, and reflect the connection between the fermi level and the lower Hubbard band. The results were obtained by a mean field theory that effectively projects electrons by quantum interference between two bands of fermions instead of binding slave particles.Comment: 5 pages 2 fig

Functional renormalization group and variational Monte Carlo studies of the electronic instabilities in graphene near 1/4 doping

We study the electronic instabilities of near 1/4 electron doped graphene using the functional renormalization group (FRG) and variational Monte-Carlo method. A modified FRG implementation is utilized to improve the treatment of the von Hove singularity. At 1/4 doping the system is a chiral spin density wave state exhibiting the anomalous quantized Hall effect, or equivalently a Chern insulator. When the doping deviates from 1/4, the $d_{x^2-y^2}+i d_{xy}$ Cooper pairing becomes the leading instability. Our results suggest near 1/4 electron or hole doped graphene is a fertile playground for the search of Chern insulators and superconductors.Comment: 7 pages, 8 figures, with technical details, published versio

Impurity resonance states in electron-doped high T_c superconductors

Two scenarios, i.e., the anisotropic s-wave pairing (the s-wave scenario) and the d-wave pairing coexisting with antiferromagnetism (the coexisting scenario) have been introduced to understand some of seemingly s-wave like behaviors in electron doped cuprates. We considered the electronic structure in the presence of a nonmagnetic impurity in the coexistence scenario. We found that even if the AF order opens a full gap in quasi-particle excitation spectra, the mid-gap resonant peaks in local density of states (LDoS) around an impurity can still be observed in the presence of a d-wave pairing gap. The features of the impurity states in the coexisting phase are markedly different from the pure AF or pure d-wave pairing phases, showing the unique role of the coexisting AF and d-wave pairing orders. On the other hand, it is known that in the pure s-wave case no mid-gap states can be induced by a nonmagnetic impurity. Therefore we proposed that the response to a nonmagnetic impurity can be used to differentiate the two scenarios.Comment: 5 pages, two-column revtex4, 5 figures, author list correcte

Antigout Effects of Plantago asiatica

The XOD inhibitory effects of Plantaginis Semen, that is, the seeds of P. asiatisca, and its representative four single compounds, acteoside, 1H-indolo-3-carbaldehyde, isoacteoside, and myristic acid, were evaluated by electron transfer signal blocking activities (ETSBA), which is based on the electron transfer signal of XOD enzymatic reaction. The blocking activities were detected using an electrochemical biosensing method. Compared with control, significant effects were observed after the addition of P. asiatica extract, acteoside, and 1H-indolo-3-carbaldehyde (all p<0.05). The IC50 values of the extract and acteoside are 89.14 and 7.55 μg·mL−1, respectively. The IC20 values of the extract, acteoside, and 1H-indolo-3-carbaldehyde are 24.28, 3.88, and 16.16 μg·mL−1, respectively. Due to the relatively lower inhibitory potential of 1H-indolo-3-carbaldehyde, its IC50 was not obtained. In addition, isoacteoside and myristic acid did not show any XOD inhibitory effects. Our data demonstrated that the XOD inhibitory effects of the extract, acteoside, and 1H-indolo-3-carbaldehyde can be accurately evaluated by the ETSBA method. The results from this study indicated that Plantaginis Semen significantly inhibited XOD activities to reduce hyperuricemia and treat gout. The study also proves that measuring the electron transfer signal blocking activities is a simple, sensitive, and accurate method to evaluate the XOD inhibitory effects

Downregulation of T-cell cytotoxic marker IL18R1 promotes cancer proliferation and migration and is associated with dismal prognosis and immunity in lung squamous cell carcinoma

Immunotherapy can improve the survival of patients with advanced lung squamous cell carcinoma (LUSC). T cytotoxic cells are one of the main members of the immune microenvironment. Herein, we aimed to identify the roles of T-cell cytotoxic markers interleukin 18 (IL18) receptor 1 (IL18R1) in the LUSC progression using bioinformatics, clinical tissue specimen, and cell experiment. We assessed the association between the IL18R1 expression and immune infiltration and IL18R1-related competing RNA network. The IL18R1 expression was downregulated in the LUSC tissues. The IL18R1 expression downregulation was associated with diagnosis and short overall survival and disease-specific survival, and it was also an independent risk factor for dismal survival time in LUSC. IL18R1-related nomograms predicted the survival time of patients with LUSC. IL18R1 overexpression inhibited the proliferation, migration, and invasion of LUSC cells. The IL18R1 expression was significantly associated with the microenvironment (stromal, immune, and estimate scores), immune cells (such as the T cells, cytotoxic cells, CD8 T cells), and immune cell markers (such as the CD8A, PD-1, and CTLA4) in LUSC. AC091563.1 and RBPMS-AS1 downregulation was positively associated with the IL18R1 expression, negatively associated with the miR-128-3p expression, and associated with short disease-specific survival and progression in LUSC. In conclusion, IL18R1 was significantly downregulated and associated with the prognosis and immune microenvironment. IL18R1 overexpression inhibits the growth and migration of cancer cells in LUSC. Furthermore, AC091563.1 and RBPMS-AS1 might compete with IL18R1 to bind miR-128-3p for participating in LUSC progression. These results showed that IL18R1 is a biomarker for evaluating the prognosis of patients with LUSC

Pairing symmetry and properties of iron-based high temperature superconductors

Pairing symmetry is important to indentify the pairing mechanism. The analysis becomes particularly timely and important for the newly discovered iron-based multi-orbital superconductors. From group theory point of view we classified all pairing matrices (in the orbital space) that carry irreducible representations of the system. The quasiparticle gap falls into three categories: full, nodal and gapless. The nodal-gap states show conventional Volovik effect even for on-site pairing. The gapless states are odd in orbital space, have a negative superfluid density and are therefore unstable. In connection to experiments we proposed possible pairing states and implications for the pairing mechanism.Comment: 4 pages, 1 table, 2 figures, polished versio