Magnetic structures of organic Mott insulators XPd(dmit)_{2}_{2} (X=Me_{4}P, Me_{4}Sb), of which electronic states are located near a quantum spin liquid (X=EtMe_{3}Sb), are demonstrated by ^{13}C ...nuclear magnetic resonance. Antiferromagnetic spectra and nuclear relaxations show two distinct magnetic moments within each Pd(dmit)_{2} molecule, which cannot be described by single band dimer-Mott model and requires intramolecular electronic correlation. This unconventional fragmentation of S=1/2 electron spin with strong quantum fluctuation is presumably caused by nearly degenerated intramolecular multiple orbitals, and shares a notion of quantum liquids where electronic excitations are fractionalized and S=1/2 spin is no longer an elementary particle.
Multi-targeted tyrosine kinase inhibitors have been developed for the treatment of various cancers, but they are associated with a significant incidence of idiosyncratic drug reactions (IDRs). There ...is compelling evidence that most IDRs are immune mediated. Activation of inflammasomes is often one of the early steps in the initiation of an immune response. This activation could involve the pharmacological effect of the drug, or it could involve the release of damage associated molecular patters (DAMPs) caused by a reactive metabolite. We tested whether sunitinib, regorafenib, lenvatinib and cabozantinib can directly activate inflammasomes in differentiated THP-1 cells. We found that regorafenib activated the inflammasome of differentiated THP-1 cells directly. We also found that the supernatant from the incubation of sunitinib with FLC-4 cells, which have a high capacity to metabolize drugs, led to activate the inflammasome of differentiated THP-1 cells. In the supernatant of FLC-4 cells with sunitinib, the heat shock protein (HSP) 90 was significantly increased. Sunitinib is known to be oxidized to generate a reactive, potentially toxic quinone imine. These results support the hypothesis that the reactive metabolite of sunitinib can cause the release of DAMPs from hepatocytes, which leads to activation of inflammasomes. Inflammasome activation may be an important step in the activation of the immune system by regorafenib and sunitinib, which in some patients, can cause IDRs.
The transition of a Mott insulator to metal, the Mott transition, can occur via carrier doping by elemental substitution, and by photoirradiation, as observed in transition-metal compounds and in ...organic materials. Here, we show that the application of a strong electric field can induce a Mott transition by a new pathway, namely through impulsive dielectric breakdown. Irradiation of a terahertz electric-field pulse on an ET-based compound, κ-(ET)
CuN(CN)
Br (ET:bis(ethylenedithio)tetrathiafulvalene), collapses the original Mott gap of ∼30 meV with a ∼0.1 ps time constant after doublon-holon pair productions by quantum tunnelling processes, as indicated by the nonlinear increase of Drude-like low-energy spectral weights. Additionally, we demonstrate metallization using this method is faster than that by a femtosecond laser-pulse irradiation and that the transition dynamics are more electronic and coherent. Thus, strong terahertz-pulse irradiation is an effective approach to achieve a purely electronic Mott transition, enhancing the understanding of its quantum nature.
To improve productivity of assembly in cell production, a robot is introduced to help operators physically. A moving robot around a human operator however induces much stress on human operators ...because they need to work coexistently and compellingly with the robot. This paper deals with the strain measurement caused by industrial robots, and the discuss design criterions of robot collaboration with a human operator. Several basic strains are experimentally measured: distance from a swinging robot to an operator, speed at robot's movement towards an operator and so on. The results are applied in a novel cell production assembly system.
Quantum liquids-known to be realized in 3He, 4He and electronsin metals-generally exhibit instabilities unforeseen under classical Newtonian dynamics, such as the superfluid and superconducting ...transitions. Recently, a new quantum liquid, now known as the quantum spin liquid, has been discovered in frustrated antiferromagnetic spin-1/2 systems. In this state, quantum fluctuations of spins prevent classical antiferromagnetic ordering even at absolute zero, similar to the situation in the well-known quantum liquids. A fundamental question that has remained open is whether instabilities other than classical ordering can occur in a quantum spin liquid, as well as in the well-known quantum liquids. Here we demonstrate experimentally that a quantum spin liquid in an organic triangular-lattice antiferromagnet undergoes an instability involving symmetry breaking and/or topological ordering, possibly giving rise to a new quantum state of matter. Our result reveals a new variety of quantum-liquid instability, which might become a comparable concept to the already-known fermion-liquid instabilities (such as Bardeen-Cooper-Schrieffer pairing and Peierls instability) and boson-liquid instability (Bose-Einstein condensation).
Abstract
Coherent radiation from a short bunch of electron beams is expected to be utilized as a terahertz (THz) radiation source. We have conducted an investigation on a terahertz source based on ...coherent diffraction-radiation (CDR) that possesses a unique characteristic of radial polarization and is potentially useful for certain applications. Particularly, with the high repetition beam of an energy-recovery linac, it is possible to achieve a watt-class high power source. We have designed a CDR setup and THz transport line, and subsequently measured the THz beam profile at the end of the line. The results confirmed the preservation of the distinctive characteristics of CDR within the experimental area.
We present the ultralow-temperature specific heat and thermal conductivity measurements on single crystals of triangular-lattice compound EtMe3SbPd(dmit)22, which has long been considered as a ...gapless quantum spin liquid candidate. In specific heat measurements, a finite linear term is observed, consistent with the previous work S. Yamashita et al., Nat. Commun. 2, 275 (2011). However, we do not observe a finite residual linear term in the thermal conductivity measurements, and the thermal conductivity does not change in a magnetic field of 6 T. These results are in sharp contrast to previous thermal conductivity measurements on EtMe3SbPd(dmit)22 M. Yamashita et al., Science 328, 1246 (2010), in which a huge residual linear term was observed and attributed to highly mobile gapless excitations, likely the spinons of a quantum spin liquid. In this context, the true ground state of EtMe3SbPd(dmit)22 has to be reconsidered.
The localization of charge carriers by electronic repulsion was suggested by Mott in the 1930s to explain the insulating state observed in supposedly metallic NiO. The Mott metal-insulator transition ...has been subject of intense investigations ever since
-not least for its relation to high-temperature superconductivity
. A detailed comparison to real materials, however, is lacking because the pristine Mott state is commonly obscured by antiferromagnetism and a complicated band structure. Here we study organic quantum spin liquids, prototype realizations of the single-band Hubbard model in the absence of magnetic order. Mapping the Hubbard bands by optical spectroscopy provides an absolute measure of the interaction strength and bandwidth-the crucial parameters that enter calculations. In this way, we advance beyond conventional temperature-pressure plots and quantitatively compose a generic phase diagram for all genuine Mott insulators based on the absolute strength of the electronic correlations. We also identify metallic quantum fluctuations as a precursor of the Mott insulator-metal transition, previously predicted but never observed. Our results suggest that all relevant phenomena in the phase diagram scale with the Coulomb repulsion U, which provides a direct link to unconventional superconductivity in cuprates and other strongly correlated materials.
A Dirac electron system in solids mimics relativistic quantum physics that is compatible with Maxwell's equations, with which we anticipate unified electromagnetic responses. We find a large orbital ...diamagnetism only along the interplane direction and a nearly temperature-independent electrical conductivity of the order of e^{2}/h per plane for the new 2D Dirac organic conductor, α-(BETS)_{2}I_{3}, where BETS is bis(ethylenedithio)tetraselenafulvalene. Unlike conventional electrons in solids whose nonrelativistic effects bifurcate electric and magnetic responses, the observed orbital diamagnetism scales with the electrical conductivity in a wide temperature range. This demonstrates that an electromagnetic duality that is valid only within the relativistic framework is revived in solids.
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