1,202 research outputs found
Spin-Orbit Coupling in Iridium-Based 5d Compounds Probed by X-ray Absorption Spectroscopy
We have performed x-ray absorption spectroscopy (XAS) measurements on a
series of Ir-based 5d transition metal compounds, including Ir, IrCl3, IrO2,
Na2IrO3, Sr2IrO4, and Y2Ir2O7. By comparing the intensity of the "white-line"
features observed at the Ir L2 and L3 absorption edges, it is possible to
extract valuable information about the strength of the spin-orbit coupling in
these systems. We observe remarkably large, non-statistical branching ratios in
all Ir compounds studied, with little or no dependence on chemical composition,
crystal structure, or electronic state. This result confirms the presence of
strong spin-orbit coupling effects in novel iridates such as Sr2IrO4, Na2IrO3,
and Y2Ir2O7, and suggests that even simple Ir-based compounds such as IrO2 and
IrCl3 may warrant further study. In contrast, XAS measurements on Re-based 5d
compounds, such as Re, ReO2, ReO3, and Ba2FeReO6, reveal statistical branching
ratios and negligible spin-orbit coupling effects.Comment: 9 pages, 4 figure
Improved description of Ar(p,d) transfer reactions
An improved description of single neutron stripping from Ar
beams at 33 MeV/nucleon by a hydrogen target is presented and the dependence on
the neutron-proton asymmetry of the spectroscopic factors is further
investigated. A finite range adiabatic model is used in the analysis and
compared to previous zero range and local energy approximations. Full
three-body Faddeev calculations are performed to estimate the error in the
reaction theory. In addition, errors from the optical potentials are also
evaluated. From our new spectroscopic factors extracted from transfer, it is
possible to corroborate the neutron-proton asymmetry dependence reported from
knockout measurements.Comment: 7 pages, 3 figure
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A safety-modified SV40 Tag developed for human cancer immunotherapy
Simian virus 40 (SV40)-like DNA sequences have been found in a variety of human tumors, raising the possibility that strategies targeting SV40 may provide a potential avenue for immunotherapy directed against SV40 large T Antigen (Tag)-expressing tumors. We generated a recombinant vaccinia (vac-mTag) expressing mTag and herein assessed the ability of mTag to transform cells and to interact with anti-oncoproteins, as well as screened for the presence of potential HLA-A2.1-restricted epitopes within mTag. We found that transfection of cells with mTag did not lead to their transformation. Also, we demonstrated that mTag protein is degraded rapidly in cells. In addition, our work revealed that mTag did not physically interact with certain anti-oncoproteins. Finally, two potential HLA-A2.1-restricted functional epitopes within mTag sequence were identified. Our results show that mTag lacks the oncogenecity of full-length Tag and harbors potential HLA-A2.1-restricted immunogenic epitopes, hence suggesting the safety of vac-mTag for use in cancer immunotherapy
Dirac magnons in a honeycomb lattice quantum XY magnet CoTiO3
The discovery of massless Dirac electrons in graphene and topological
Dirac-Weyl materials has prompted a broad search for bosonic analogues of such
Dirac particles. Recent experiments have found evidence for Dirac magnons above
an Ising-like ferromagnetic ground state in a two-dimensional (2D) kagome
lattice magnet and in the van der Waals layered honeycomb crystal CrI, and
in a 3D Heisenberg magnet CuTeO. Here we report on our inelastic
neutron scattering investigation on large single crystals of a stacked
honeycomb lattice magnet CoTiO, which is part of a broad family of ilmenite
materials. The magnetically ordered ground state of CoTiO features
ferromagnetic layers of Co, stacked antiferromagnetically along the
-axis. We discover that the magnon dispersion relation exhibits strong
easy-plane exchange anisotropy and hosts a clear gapless Dirac cone along the
edge of the 3D Brillouin zone. Our results establish CoTiO as a model
pseudospin- material to study interacting Dirac bosons in a 3D quantum XY
magnet.Comment: 7 pages, 5 figures; Supplemental Materials Available upon reques
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