Pre-logarithmic and logarithmic fields in a sandpile model

We consider the unoriented two-dimensional Abelian sandpile model on the half-plane with open and closed boundary conditions, and relate it to the boundary logarithmic conformal field theory with central charge c=-2. Building on previous results, we first perform a complementary lattice analysis of the operator effecting the change of boundary condition between open and closed, which confirms that this operator is a weight -1/8 boundary primary field, whose fusion agrees with lattice calculations. We then consider the operators corresponding to the unit height variable and to a mass insertion at an isolated site of the upper half plane and compute their one-point functions in presence of a boundary containing the two kinds of boundary conditions. We show that the scaling limit of the mass insertion operator is a weight zero logarithmic field.Comment: 18 pages, 9 figures. v2: minor corrections + added appendi

The para-substituent effect and pH-dependence of the organometallic Baeyer–Villiger oxidation of rhenium–carbon bonds

We studied the Baeyer–Villiger (BV) type oxidation of phenylrhenium trioxide (PTO) by H2O2 in the aqueous phase using Quantum Mechanics (density functional theory with the M06 functional) focusing on how the solution pH and the para-substituent affect the Gibbs free energy surfaces. For both PTO and MTO (methylrhenium trioxide) cases, we find that for pH > 1 the BV pathway having OH− as the leaving group is lower in energy than the one involving simultaneous protonation of hydroxide. We also find that during this organometallic BV oxidation, the migrating phenyl is a nucleophile so that substituting functional groups in the para-position of phenyl with increased electron-donating character lowers the migration barrier, just as in organic BV reactions. However, this substituent effect also pushes electron density to Re, impeding HOO− coordination and slowing down the reaction. This is in direct contrast to the organic analog, in which para-substitution has an insignificant influence on 1,2-addition of peracids. Due to the competition of the two opposing effects and the dependence of the resting state on pH and concentration, the reaction rate of the organometallic BV oxidation is surprisingly unaffected by para-substitution

Functionalization of Rhenium Aryl Bonds by O-Atom Transfer

Aryltrioxorhenium (ArReO_3) has been demonstrated to show rapid oxy-functionalization upon reaction with O-atom donors, YO, to selectively generate the corresponding phenols in near quantitative yields. (18)^O-Labeling experiments show that the oxygen in the products is exclusively from YO. DFT studies reveal a 10.7 kcal/mol barrier (Ar = Ph) for oxy-functionalization with H_2O_2 via a Baeyer-Villiger type mechanism involving nudeophilic attack of the aryl group on an electrophilic oxygen of YO coordinated to rhenium

Surface electronic structure of a topological Kondo insulator candidate SmB6: insights from high-resolution ARPES

The Kondo insulator SmB6 has long been known to exhibit low temperature (T < 10K) transport anomaly and has recently attracted attention as a new topological insulator candidate. By combining low-temperature and high energy-momentum resolution of the laser-based ARPES technique, for the first time, we probe the surface electronic structure of the anomalous conductivity regime. We observe that the bulk bands exhibit a Kondo gap of 14 meV and identify in-gap low-lying states within a 4 meV window of the Fermi level on the (001)-surface of this material. The low-lying states are found to form electron-like Fermi surface pockets that enclose the X and the Gamma points of the surface Brillouin zone. These states disappear as temperature is raised above 15K in correspondence with the complete disappearance of the 2D conductivity channels in SmB6. While the topological nature of the in-gap metallic states cannot be ascertained without spin (spin-texture) measurements our bulk and surface measurements carried out in the transport-anomaly-temperature regime (T < 10K) are consistent with the first-principle predicted Fermi surface behavior of a topological Kondo insulator phase in this material.Comment: 4 Figures, 6 Page

New interleukin-15 superagonist (IL-15SA) significantly enhances graft-versus-tumor activity.

Interleukin-15 (IL-15) is a potent cytokine that increases CD8+ T and NK cell numbers and function in experimental models. However, obstacles remain in using IL-15 therapeutically, specifically its low potency and short in vivo half-life. To help overcome this, a new IL-15 superagonist complex comprised of an IL-15N72D mutation and IL-15RαSu/Fc fusion (IL-15SA, also known as ALT-803) was developed. IL-15SA exhibits a significantly longer serum half-life and increased in vivo activity against various tumors. Herein, we evaluated the effects of IL-15SA in recipients of allogeneic hematopoietic stem cell transplantation. Weekly administration of IL-15SA to transplant recipients significantly increased the number of CD8+ T cells (specifically CD44+ memory/activated phenotype) and NK cells. Intracellular IFN-γ and TNF-α secretion by CD8+ T cells increased in the IL-15SA-treated group. IL-15SA also upregulated NKG2D expression on CD8+ T cells. Moreover, IL-15SA enhanced proliferation and cytokine secretion of adoptively transferred CFSE-labeled T cells in syngeneic and allogeneic models by specifically stimulating the slowly proliferative and nonproliferative cells into actively proliferating cells.We then evaluated IL-15SA\u27s effects on anti-tumor activity against murine mastocytoma (P815) and murine B cell lymphoma (A20). IL-15SA enhanced graft-versus-tumor (GVT) activity in these tumors following T cell infusion. Interestingly, IL-15 SA administration provided GVT activity against A20 lymphoma cells in the murine donor leukocyte infusion (DLI) model without increasing graft versus host disease. In conclusion, IL-15SA could be a highly potent T- cell lymphoid growth factor and novel immunotherapeutic agent to complement stem cell transplantation and adoptive immunotherapy

Selective interlayer ferromagnetic coupling between the Cu spins in YBa2_2 Cu3_3 O7−x_{7-x} grown on top of La0.7_{0.7} Ca0.3_{0.3} MnO3_3

Studies to date on ferromagnet/d-wave superconductor heterostructures focus mainly on the effects at or near the interfaces while the response of bulk properties to heterostructuring is overlooked. Here we use resonant soft x-ray scattering spectroscopy to reveal a novel c-axis ferromagnetic coupling between the in-plane Cu spins in YBa$_2$ Cu$_3$ O$_{7-x}$ (YBCO) superconductor when it is grown on top of ferromagnetic La$_{0.7}$ Ca$_{0.3}$ MnO$_3$ (LCMO) manganite layer. This coupling, present in both normal and superconducting states of YBCO, is sensitive to the interfacial termination such that it is only observed in bilayers with MnO_2but not with La$_{0.7}$ Ca$_{0.3}$ interfacial termination. Such contrasting behaviors, we propose, are due to distinct energetic of CuO chain and CuO$_2$ plane at the La$_{0.7}$ Ca$_{0.3}$ and MnO$_2$ terminated interfaces respectively, therefore influencing the transfer of spin-polarized electrons from manganite to cuprate differently. Our findings suggest that the superconducting/ferromagnetic bilayers with proper interfacial engineering can be good candidates for searching the theorized Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state in cuprates and studying the competing quantum orders in highly correlated electron systems.Comment: Please note the change of the title. Text might be slightly different from the published versio