Controlling the chiral degree of freedom in matter has long been an important issue for many fields of science. The spin-spiral order, which exhibits a strong magnetoelectric coupling, gives rise to ...chirality irrespective of the atomic arrangement of matter. Here, we report the resonantly enhanced natural optical activity on the electrically active magnetic excitation, that is, electromagnon, in multiferroic cupric oxide. The electric field control of the natural optical activity is demonstrated through magnetically induced chirality endowed with magnetoelectric coupling. These optical properties inherent to multiferroics may lead to optical devices based on the control of chirality.
It was recently realized that topological spin textures do not merely have mathematical beauty but can also give rise to unique functionalities of magnetic materials. An example is the skyrmion—a ...nano-sized bundle of noncoplanar spins—that by virtue of its nontrivial topology acts as a flux of magnetic field on spin-polarized electrons. Lorentz transmission electron microscopy recently emerged as a powerful tool for direct visualization of skyrmions in noncentrosymmetric helimagnets. Topologically, skyrmions are equivalent to magnetic bubbles (cylindrical domains) in ferromagnetic thin films, which were extensively explored in the 1970s for data storage applications. In this study we use Lorentz microscopy to image magnetic domain patterns in the prototypical magnetic oxide–M-type hexaferrite with a hint of scandium. Surprisingly, we find that the magnetic bubbles and stripes in the hexaferrite have a much more complex structure than the skyrmions and spirals in helimagnets, which we associate with the new degree of freedom—helicity (or vector spin chirality) describing the direction of spin rotation across the domain walls. We observe numerous random reversals of helicity in the stripe domain state. Random helicity of cylindrical domain walls coexists with the positional order of magnetic bubbles in a triangular lattice. Most unexpectedly, we observe regular helicity reversals inside skyrmions with an unusual multiple-ring structure.
Ripasudil hydrochloride hydrate (K-115), a specific Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor, was the first ophthalmic solution developed for the treatment of glaucoma ...and ocular hypertension in Japan. Topical administration of K-115 decreased intraocular pressure (IOP) and increased outflow facility in rabbits. This study evaluated the effect of K-115 on monkey trabecular meshwork (TM) cells and Schlemm's canal endothelial (SCE) cells. K-115 induced retraction and rounding of cell bodies as well as disruption of actin bundles in TM cells. In SCE-cell monolayer permeability studies, K-115 significantly decreased transendothelial electrical resistance (TEER) and increased the transendothelial flux of FITC-dextran. Further, K-115 disrupted cellular localization of ZO-1 expression in SCE-cell monolayers. These results indicate that K-115 decreases IOP by increasing outflow facility in association with the modulation of TM cell behavior and SCE cell permeability in association with disruption of tight junction.
Lattice defect is a major cause of energy dissipation in conventional electric current due to the drift and diffusion motions of electrons. Different nature of current emerges when noncentrosymmetric ...materials are excited by light. This current, called the shift current, originates from the change in the Berry connection of electrons’ wave functions during the interband optical transition. Here, we demonstrate the defect tolerance of shift current using single crystals of ferroelectric semiconductor antimony sulfoiodide (SbSI). Although the dark conductance spreads over several orders of magnitude in each crystal due to the difference in the density of defect levels, the observed shift current converges to an identical value. We also reveal that the shift current is scarcely disturbed by the surface defects while they drastically suppress the conventional photocurrent. The defect tolerance is a manifestation of the topological nature of shift current, which will be a crucial advantage in optoelectronic applications.
Abstract Direct conversion from terahertz photon to charge current is a key phenomenon for terahertz photonics. Quantum geometrical description of optical processes in crystalline solids predicts ...existence of field-unbiased dc photocurrent arising from terahertz-light generation of magnetic excitations in multiferroics, potentially leading to fast and energy-efficient terahertz devices. Here, we demonstrate the dc charge current generation from terahertz magnetic excitations in multiferroic perovskite manganites with spin-driven ferroelectricity, while keeping an insulating state with no free carrier. It is also revealed that electromagnon, which ranges sub-terahertz to 2 THz, as well as antiferromagnetic resonance shows the giant conversion efficiency. Polar asymmetry induced by the cycloidal spin order gives rise to this terahertz-photon-induced dc photocurrent, and no external magnetic and electric bias field are required for this conversion process. The observed phenomena are beyond the conventional photovoltaics in semi-classical regime and demonstrate the essential role of quantum geometrical aspect in low-energy optical processes. Our finding establishes a paradigm of terahertz photovoltaic phenomena, paving a way for terahertz photonic devices and energy harvesting.
Abstract
Purpose: To evaluate the topical instillation of K-115, a selective Rho-associated coiled coil-containing protein kinase (ROCK) inhibitor, on intraocular pressure (IOP), ocular distribution, ...and aqueous humor dynamics in experimental animals.
Methods: Kinase inhibition by K-115 was measured by biochemical assay. IOP was monitored using a pneumatonometer in albino rabbits and monkeys after topical instillation of K-115. The ocular distribution of 14CK-115 was determined by whole-head autoradiography. The aqueous flow rate was determined by fluorophotometry. The total outflow facility and uveoscleral outflow were measured by two-level constant pressure perfusion and perfusion technique using fluorescein isothiocyanate-dextran, respectively.
Results: Biochemical assay showed that K-115 had selective and potent inhibitory effects on ROCKs. In rabbits, topical instillation of K-115 significantly reduced IOP in a dose-dependent manner. Maximum IOP reduction was observed 1 h after topical instillation, which was 8.55 ± 1.09 mmHg (mean ± SE) from the baseline IOP at 0.5%. In monkeys, maximum IOP reduction was observed 2 h after topical instillation, which was 4.36 ± 0.32 mmHg from the baseline IOP at 0.4%, and was significantly stronger than that of 0.005% latanoprost. Whole-head autoradiography showed that the radioactivity level was maximum at 15 min after instillation of 14CK-115 in the ipsilateral eye. Single instillation of 0.4% K-115 showed no effect on aqueous flow rate or uveoscleral outflow, but significantly increased conventional outflow facility by 2.2-fold compared to vehicle-treated eyes in rabbits.
Conclusions: These results indicated that K-115 ophthalmic solution, a selective and potent ROCK inhibitor, is a novel and potent antiglaucoma agent.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Weyl fermions that emerge at band crossings in momentum space caused by the spin-orbit interaction act as magnetic monopoles of the Berry curvature and contribute to a variety of novel transport ...phenomena such as anomalous Hall effect and magnetoresistance. However, their roles in other physical properties remain mostly unexplored. Here, we provide evidence by neutron Brillouin scattering that the spin dynamics of the metallic ferromagnet SrRuO3 in the very low energy range of milli-electron volts is closely relevant to Weyl fermions near Fermi energy. Although the observed spin wave dispersion is well described by the quadratic momentum dependence, the temperature dependence of the spin wave gap shows a nonmonotonous behaviour, which can be related to that of the anomalous Hall conductivity. This shows that the spin dynamics directly reflects the crucial role of Weyl fermions in the metallic ferromagnet.
The quest for nonmagnetic Weyl semimetals with high tunability of phase has remained a demanding challenge. As the symmetry-breaking control parameter, the ferroelectric order can be steered to turn ...on/off the Weyl semimetals phase, adjust the band structures around the Fermi level, and enlarge/shrink the momentum separation of Weyl nodes which generate the Berry curvature as the emergent magnetic field. Here, we report the realization of a ferroelectric nonmagnetic Weyl semimetal based on indium-doped Pb
Sn
Te alloy in which the underlying inversion symmetry as well as mirror symmetry are broken with the strength of ferroelectricity adjustable via tuning the indium doping level and Sn/Pb ratio. The transverse thermoelectric effect (i.e., Nernst effect), both for out-of-plane and in-plane magnetic field geometry, is exploited as a Berry curvature-sensitive experimental probe to manifest the generation of Berry curvature via the redistribution of Weyl nodes under magnetic fields. The results demonstrate a clean, nonmagnetic Weyl semimetal coupled with highly tunable ferroelectric order, providing an ideal platform for manipulating the Weyl fermions in nonmagnetic systems.
Photovoltaic effect by soft phonon excitation Okamura, Yoshihiro; Morimoto, Takahiro; Ogawa, Naoki ...
Proceedings of the National Academy of Sciences - PNAS,
04/2022, Letnik:
119, Številka:
14
Journal Article
Recenzirano
Odprti dostop
SignificanceThe quantum-mechanical geometric phase of electrons provides various phenomena such as the dissipationless photocurrent generation through the shift current mechanism. So far, the ...photocurrent generations are limited to above or near the band-gap photon energy, which contradicts the increasing demand of the low-energy photonic functionality. We demonstrate the photocurrent through the optical phonon excitations in ferroelectric BaTiO
by using the terahertz light with photon energy far below the band gap. This photocurrent without electron-hole pair generation is never explained by the semiclassical treatment of electrons and only arises from the quantum-mechanical geometric phase. The observed photon-to-current conversion efficiency is as large as that for electronic excitation, which can be well accounted for by newly developed theoretical formulation of shift current.
1. We examined the metabolism of ripasudil (K-115), a selective and potent Rho-associated coiled coil-containing protein kinase (ROCK) inhibitor, by in vitro and in vivo studies.
2. First, we ...identified metabolites and metabolic enzymes involved in ripasudil metabolism. Species differences were observed in metabolic clearance and profiles of metabolites in liver S9 fraction and hepatocytes. In addition, ripasudil was metabolised in humans and monkey S9 without nicotinamide adenine dinucleotide phosphate (NADPH). Studies using specific inhibitors and human recombinant enzyme systems showed that M1 (main metabolite in humans) formation is mediated by aldehyde oxidase (AO).
3. Therefore, we developed ripasudil as an ophthalmic agent. First, we compared the pharmacokinetic profiles of ripasudil in humans and rats. The results indicated rapid disappearance of ripasudil from the circulation after instillation in humans and its level remained relatively high only in M1. In contrast, we found six metabolites from M1 to M6 in plasma after oral administration to rats.
4. Analysis of enzyme kinetics using S9 showed that the formation of M1 is the major metabolic pathway of ripasudil in humans even though CYP3A4/3A5 and CYP2C8/3A4/3A5 were associated with the formation of M2 and M4, respectively. In conclusion, AO causes differences in ripasudil metabolism between species.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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