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Abstract Memristors, or more generally “memristive systems,” are nonlinear electric components that change their resistance depending on a set of state variables. Meanwhile, negative differential resistance (NDR) is an uncommon electrical property that occurs in a few nonlinear electric components. Such a nonlinear property is now widely used in amplifiers and oscillators. It finds that one of the bilayer‐type nickel‐dithiolene complexes shows nonlinear transport with the NDR property and self‐oscillates under a bias current by simply adding a capacitor in parallel. Surprisingly, the Lissajous figure of this molecular material shows a “pinched hysteresis loop” typical of a memristor, and an inductive reactance emerges when a bias current or voltage is applied to the sample. Herein, a new type of oscillator that uses the NDR and hidden inductive properties of a memristive system is reported. The findings suggest that a memristive system can mimic other passive elements, such as an inductor, and can oscillate itself without having them in the circuit. The oscillation mechanism is straightforward and applicable to a wide variety of memristive materials, including resistors with large negative temperature coefficients, discharge tubes, and even nerve cells in the living body.

Abstract Magnetic properties of Mott–Hubbard systems are generally dominated by strong antiferromagnetic interactions produced by the Coulomb repulsion of electrons. Although theoretical possibility of a ferromagnetic ground state has been suggested by Nagaoka and Penn as single-hole doping in a Mott insulator, experimental realization has not been reported more than half century. We report the first experimental possibility of such ferromagnetism in a molecular Mott insulator with an extremely light and homogeneous hole-doping in π-electron layers induced by net polarization of counterions. A series of Ni(dmit)2 anion radical salts with organic cations, where dmit is 1,3-dithiole-2-thione-4,5-dithiolate can form bi-layer structure with polarized cation layers. Heat capacity, magnetization, and ESR measurements substantiated the formation of a bulk ferromagnetic state around 1.0 K with quite soft magnetization versus magnetic field (M–H) characteristics in (Et-4BrT)[Ni(dmit)2]2 where Et-4BrT is ethyl-4-bromothiazolium. The variation of the magnitude of net polarizations by using the difference of counter cations revealed the systematic change of the ground state from antiferromagnetic one to ferromagnetic one. We also report emergence of metallic states through further doping and applying external pressures for this doping induced ferromagnetic state. The realization of ferromagnetic state in Nagaoka–Penn mechanism can paves a way for designing new molecules-based ferromagnets in future.

Abstract We previously reported the importance of induced nuclear transglutaminase (TG) 2 activity, which results in hepatic cell death, in ethanol-induced liver injury. Here, we show that co-incubation of either human hepatic cells or mouse primary hepatocytes derived from wild-type but not TG2−/− mice with pathogenic fungi Candida albicans and C. glabrata, but not baker’s yeast Saccharomyces cerevisiae, induced cell death in host cells by enhancing cellular, particularly nuclear, TG activity. Further pharmacological and genetic approaches demonstrated that this phenomenon was mediated partly by the production of reactive oxygen species (ROS) such as hydroxyl radicals, as detected by a fluorescent probe and electron spin resonance. A ROS scavenger, N-acetyl cysteine, blocked enhanced TG activity primarily in the nuclei and inhibited cell death. In contrast, deletion of C. glabrata nox-1, which encodes a ROS-generating enzyme, resulted in a strain that failed to induce the same phenomena. A similar induction of hepatic ROS and TG activities was observed in C. albicans-infected mice. An antioxidant corn peptide fraction inhibited these phenomena in hepatic cells. These results address the impact of ROS-generating pathogens in inducing nuclear TG2-related liver injuries, which provides novel therapeutic targets for preventing and curing alcoholic liver disease.

There are few reports on zero-field-cooled (ZFC) magnetization measurements for Fe@FeOx or FeOx particles synthesized by laser ablation in liquids (LAL) of Fe, and the minimum blocking temperature (TB) of 120 K reported so far is still much higher than those of their counterparts synthesized by chemical methods. In this work, the minimum blocking temperature was lowered to 52 K for 4–5 nm α-Fe2O3 particles synthesized by femtosecond laser ablation of Fe in acetone. The effective magnetic anisotropy energy density (Keff) is calculated to be 2.7–5.4 × 105 J/m3, further extending the Keff values for smaller hematite particles synthesized by different methods. Large amorphous-Fe@α-Fe2O3 and amorphous-Fe@C particles of 10–100 nm in diameter display a soft magnetic behavior with saturation magnetization (Ms) and coercivities (Hc) values of 72.5 emu/g and 160 Oe at 5 K and 61.9 emu/g and 70 Oe at 300 K, respectively, which mainly stem from the magnetism of amorphous Fe cores. Generally, the nanoparticles obtained by LAL are either amorphous or polycrystalline, seldom in a single-crystalline state. This work also demonstrates the possibility of synthesizing single-crystalline α-Fe2O3 hematite crystals of several nanometers with (104), (113), (116) or (214) crystallographic orientations, which were produced simultaneously with other products including carbon encapsulated amorphous Fe (a-Fe@C) and Fe@FeOx core-shell particles by LAL in one step. Finally, the formation mechanisms for these nanomaterials are proposed and the key factors in series events of LAL are discussed.

The antiferromagnetic insulating ground state of the π-d molecular conductor λ-(BETS)2FeCl4 has been under intense debate for the last decades. One of the difficulties in studying this system comes from the needle-shape of its single crystal where crystallographic a+- and b+-axes are difficult to identify. We performed electron spin resonance (ESR) measurements of λ-(BETS)2FeCl4 with precise angular dependence of the g-value to study the relation between the principal axes of the g-tensor and the crystallographic axes. In the paramagnetic metal phase, the angular dependence of the g-value shows a characteristic "canine-teeth" structure owing to the strong π-d interaction. This structure develops rapidly below 150K suggesting the enhancement of the π-d spin correlation. The principal axes of the g-value are related to the crystal axes, and a simple two-step method using ESR measurements, (i) find the g-value maximum in the a+b+-plane, and (ii) find the linewidth maximum in the b+c-plane, was examined to find the easy-axis of the antiferromagnetic state. Using the two-step method, we found that antiferromagnetic resonance of the easy-axis appears below 11 K, which is higher than the metal-insulator transition temperature. [ABSTRACT FROM AUTHOR]

Recently, advanced research into fine filament technology for tape-shaped superconducting-coated conductors composed of REBa2Cu3O7–δ (RE123, RE: rare earth such as Gd or Y, 0 < δ < 1) has been carried out to improve performance in high magnetic fields by reducing the large diamagnetism of the RE123 superconducting layer. The major challenge for high-field NMR/MRI applications is to obtain high tensile stress tolerance above 500 MPa with a high critical current. In this study, a RE123 multi-core superconductor was fabricated via an ‘inner split’ method using a commercially available RE123 single-core coated conductor, where only the ceramics (RE123 and buffer layers) in wire are electrically separated to multi-filaments without superconducting current flow between the filaments. Experimental results show that wires having 2, 3, 4, or 5 cores have a high critical current (above 95% of the original) and maintain tensile stress tolerance above 650 MPa. The diamagnetism of the five-core wire is reduced ∼85% of the original at 7 T. Thus, the wire was optimized via inner split method for high-field use. [ABSTRACT FROM AUTHOR]

Correlated electron systems can undergo ultrafast photoinduced phase transitions involving concerted transformations of electronic and lattice structure. Understanding these phenomena requires identifying the key structural modes that couple to the electronic states.We report the ultrafast photoresponse of the molecular crystal Me4P[Pt(dmit)2]2, which exhibits a photoinduced charge transfer similar to transitions between thermally accessible states, and demonstrate how femtosecond electron diffraction can be applied to directly observe the associatedmolecularmotions. Even for such a complex system, the key large-amplitudemodes can be identified by eye and involve a dimer expansion and a librationalmode.The dynamics are consistent with the time-resolved optical study, revealing how the electronic, molecular, and lattice structures together facilitate ultrafast switching of the state. [ABSTRACT FROM AUTHOR]

Our periodic orbit resonance (POR) results on quasi-two-dimensional (q2D), highly anisotropic q2D and quasi-one-dimensional (q1D) organic conductors are reviewed together with our rotational cavity magneto-optical measurement system. Higher order POR up to seventh order has been observed in the q2D system (BEDT-TTF)2Br(DIA), and the experimental conditions to observe POR and the cyclotron resonance (CR) are discussed. Highly anisotropic q2D Fermi surface (FS) in β''-(BEDT-TTF)(TCNQ), which was considered to have q1D FS previously, is proposed by our POR measurements, and the possible interpretations of other experimental results of β''-(BEDT-TTF)(TCNQ) are discussed assuming the highly anisotropic q2D FS. Finally, detailed q1D FS of (DMET)2I3, obtained from our POR results, is discussed in connection with the typical q1D system (TMTSF)2ClO4.