56 research outputs found
Normal-state properties of the antiperovskite oxide SrSnO revealed by Sn-NMR
We have performed Sn-NMR measurements on the antiperovskite oxide
superconductor SrSnO to investigate how its normal state changes with
the Sr deficiency. A two-peak structure was observed in the NMR spectra of all
the measured samples. This suggests that the phase separation tends to occur
between the nearly stoichiometric and heavily Sr-deficient SrSnO
phases. The measurement of the nuclear spin-lattice relaxation rate
indicates that the Sr-deficient phase shows a conventional metallic behavior
due to the heavy hole doping. In contrast, the nearly stoichiometric phase
exhibits unusual temperature dependence of , attributable to the
presence of a Dirac-electron band.Comment: 5 pages, 4 figure
Transcranial Magnetic Stimulation with the Maximum Voluntary Muscle Contraction Facilitates Motor Neuron Excitability and Muscle Force
Three trials of transcranial magnetic stimulation (TMS) during the maximum voluntary muscle contraction (MVC) were repeated at 15-minute intervals for 1 hour to examine the effects on motor evoked potentials (MEPs) in the digital muscles and pinching muscle force before and after 4 high-intensity TMSs (test 1 condition) or sham TMS (test 2 condition) with MVC. Under the placebo condition, real TMS with MVC was administered only before and 1 hour after the sham TMS with MVC. Magnetic stimulation at the foramen magnum level (FMS) with MVC was performed by the same protocol as that for the test 2 condition. As a result, MEP sizes in the digital muscles significantly increased after TMS with MVC under test conditions compared with the placebo conditions (P < 0.05). Pinching muscle force was significantly larger 45 minutes and 1 hour after TMS with MVC under the test conditions than under the placebo condition (P < 0.05). FMS significantly decreased MEP amplitudes 60 minutes after the sham TMS with MVC (P < 0.005). The present results suggest that intermittently repeated TMS with MVC facilitates motor neuron excitabilities and muscle force. However, further studies are needed to confirm the effects of TMS with MVC and its mechanism
Penetration depth and gap structure in the antiperovskite oxide superconductor SrSnO revealed by SR
We report a SR study on the antiperovskite oxide superconductor
SrSnO. With transverse-field SR, we observed the increase of the
muon relaxation rate upon cooling below the superconducting transition
temperature K, evidencing bulk superconductivity. The
exponential temperature dependence of the relaxation rate at low
temperatures suggests a fully gapped superconducting state. We evaluated the
zero-temperature penetration depth to be
around 320-1020 nm. Such a large value is consistent with the picture of a
doped Dirac semimetal. Moreover, we revealed that the ratio
is larger than those of ordinary
superconductors and is comparable to those of unconventional superconductors.
The relatively high for small carrier density may hint at an
unconventional pairing mechanism beyond the ordinary phonon-mediated pairing.
In addition, zero-field SR did not provide evidence of broken
time-reversal symmetry in the superconducting state. These features are
consistent with the theoretically proposed topological superconducting state in
SrSnO, as well as with -wave superconductivity.Comment: 9 pages, 9 figures, to be published in Physical Review
Sulfonamides identified as plant immune-priming compounds in high-throughput chemical screening increase disease resistance in Arabidopsis thaliana
Plant activators are agrochemicals that protect crops from diseases by activating the plant immune system. To isolate lead compounds for use as practical plant activators, we screened two different chemical libraries composed of various bioactive substances by using an established screening procedure that can selectively identify immune-priming compounds. We identified and characterized a group of sulfonamide compounds – sulfameter, sulfamethoxypyridazine, sulfabenzamide, and sulfachloropyridazine – among the various isolated candidate molecules. These sulfonamide compounds enhanced the avirulent Pseudomonas-induced cell death of Arabidopsis suspension cell cultures and increased disease resistance in Arabidopsis plants against both avirulent and virulent strains of the bacterium. These compounds did not prevent the growth of pathogenic bacteria in minimal liquid media at 200 μM. They also did not induce the expression of defense-related genes in Arabidopsis seedlings, at least not at 24 and 48 h after treatment, suggesting that they do not act as salicylic acid analogs. In addition, although sulfonamides are known to be folate biosynthesis inhibitors, the application of folate did not restore the potentiation effects of the sulfonamides on pathogen-induced cell death. Our data suggest that sulfonamides potentiate Arabidopsis disease resistance by their novel chemical properties
S-wave Superconductivity in the Dirac Line-nodal Material CaSb2
We performed 121/123Sb-nuclear quadrupole resonance (NQR) measurements on the
superconducting (SC) line-nodal material CaSb2 in order to investigate
electronic properties in the normal and SC states from a microscopic point of
view. In the normal state, the nuclear spin-lattice relaxation rate 1/T1 for
the Sb(1) site, which is responsible for the line-nodal parts, is approximately
proportional to temperature, indicating the conventional Fermi liquid state.
From comparison with band structure calculations, it is considered that the NQR
properties related to the line-nodal character are hidden because the
conventional behavior originating from Fermi-surface parts away from the nodes
is dominant. In the SC state, a clear coherence peak just below the transition
temperature and an exponential decrease at lower temperatures were observed in
1/T1. These results strongly suggest that conventional s-wave superconductivity
with a full gap is realized in CaSb2.Comment: 6 pages, 5 figure
Searching for the Frequency of Cardiac Transthyretin Amyloidosis among Elderly Heart Failure Patients Noninvasively Using 99mTc-labeled Pyrophosphate Scintigraphy
Article信州医学雑誌 69(1): 37-44(2021)journal articl
The ground state of Sr3Ru2O7 revisited; Fermi liquid close to a ferromagnetic instability
We show that single-crystalline Sr3Ru2O7 grown by a floating-zone technique
is an isotropic paramagnet and a quasi-two dimensional metal as spin-triplet
superconducting Sr2RuO4 is. The ground state is Fermi liquid with very low
residual resistivity (3 micro ohm cm for in-plane currents) and a nearly
ferromagnetic metal with the largest Wilson ratio Rw>10 among paramagnets so
far. This contrasts with the ferromagnetic order at Tc=104 K reported on single
crystals grown by a flux method [Cao et al., Phys. Rev. B 55, R672 (1997)]. We
have also found a dramatic changeover from paramagnetism to ferromagnetism
under applied pressure. This suggests the existence of a substantial
ferromagnetic instability on the verge of a quantum phase transition in the
Fermi liquid state.Comment: 5 pages, 4 figures, to be published in Phys. Rev. B : Rapid co
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