Negative Differential Resistance Device with High Peak-to-Valley Ratio Realized by Subband Resonant Tunneling of Γ-Valley Carriers in WSe/-BN/WSe Junctions.

Resonant tunneling diodes (RTDs) are a core technology in III-V semiconductor devices. The realization of high-performance RTD using two-dimensional (2D) materials has been long awaited, but it has yet to be accomplished. To this end, we investigate a range of WSe/-BN/WSe RTD devices by varying the number of layers of source and drain WSe.

Control of Subband Energies via Interlayer Twisting in an Artificially Stacked WSe Bilayer.

Tuning the electronic structure of artificially stacked bilayer crystals using their twist angle has attracted a significant amount of interest. In this study, resonant tunneling spectroscopy was performed on trilayer WSe/-BN/twisted bilayer (tBL) WSe devices with a wide range of twist angles (θ) of tBL WSe, from 0° to 34°. We observed two resonant tunneling peaks, identified as the first and second lowest hole subbands at the valence band Γ point of tBL WSe.

Crossover between rigid and reconstructed moiré lattice in -BN-encapsulated twisted bilayer WSe with different twist angles.

A moiré lattice in a twisted-bilayer transition metal dichalcogenide (tBL-TMD) exhibits a complex atomic reconstruction effect when its twist angle is less than a few degrees. The influence of the atomic reconstruction on material properties of the tBL-TMD has been of particular interest. In this study, we performed scanning transmission electron microscopy (STEM) imaging of a moiré lattice in -BN-encapsulated twisted bilayer WSe with various twist angles.

Resonant Tunneling between Quantized Subbands in van der Waals Double Quantum Well Structure Based on Few-Layer WSe.

We demonstrate van der Waals double quantum well (vDQW) devices based on few-layer WSe quantum wells and a few-layer -BN tunnel barrier. Due to the strong out-of-plane confinement, an exfoliated WSe exhibits quantized subband states at the Γ point in its valence band. Here, we report resonant tunneling and negative differential resistance in vDQW at room temperature owing to momentum- and energy-conserved tunneling between the quantized subbands in each well.

Extracellular volume fraction by T1 mapping predicts improvement of left ventricular ejection fraction after catheter ablation in patients with non-ischemic dilated cardiomyopathy and atrial fibrillation.

Absence of myocardial fibrosis on late gadolinium enhanced (LGE) magnetic resonance imaging (MRI) is associated with improvement of left ventricular systolic function after catheter ablation (CA) for atrial fibrillation (AF) with non-ischemic dilated cardiomyopathy (NIDCM). Extracellular volume fraction (ECV) by T1 mapping has emerges as a non-invasive mean to quantify severity of myocardial fibrosis. The aim of this study was to assess the incremental value of ECV over LGE-MRI for the improvement of LVEF(∆EF) after CA in NIDCM patients.

Cyclotron Resonance Study of Monolayer Graphene under Double Moiré Potentials.

We report the first cyclotron resonance study of monolayer graphene under double-moiré potentials in which the crystal axis of graphene is nearly aligned to those of both the top and bottom hexagonal boron nitride (h-BN) layers. Under mid-infrared light irradiation, we observe cyclotron resonance absorption with the following unique features: (1) cyclotron resonance magnetic field is entirely different from that of nonaligned monolayer graphene, (2) exhibits strong electron-hole asymmetry, and (3) splitting of is observed for |ν| < 1, with the split maximum at |ν| = 1, resulting in eyeglass-shaped trajectories. These features are well explained by considering the large bandgap induced by the double moiré potentials, the electron-hole asymmetry in the Fermi velocity, and the Fermi-level-dependent enhancement of spin gaps, which suggests a large electron-electron correlation contribution in this system.

Electrical Control of Cyclotron Resonance in Dual-Gated Trilayer Graphene.

Landau levels (LLs) of ABA-stacked trilayer graphene (TLG) are described as the combination of monolayer graphene-like LLs and bilayer graphene-like LLs. They are extremely sensitive to the applied perpendicular electric displacement field . Here, we demonstrate the electrical control of cyclotron resonance (CR) in a dual-gated ABA-stacked TLG.

Onset of competence to respond to activin A in isolated eight-cell stage Xenopus animal blastomeres.

Single animal hemisphere blastomeres isolated from the eight-cell stage Xenopus embryos differentiate into mesoderm when treated with activin A, whereas when cultured without activin they form atypical epidermis. The mesoderm tissue induced by activin is different between dorsal and ventral blastomeres. In the present study, the duration and timing of activin treatment was varied, in order to identify the critical stage when animal blastomeres acquire competence to respond to activin A.

Follistatin inhibits the mesoderm-inducing activity of activin A and the vegetalizing factor from chicken embryo.

The induction of mesoderm is an important process in early amphibian development. In recent studies, activin has become an effective candidate for a natural mesoderm-inducing factor. In the present study, we show that follistatin, an activin-binding protein purified from porcine ovary, inhibits the mesoderm-inducing activity of recombinant human activin A (rh activin A), which is identical to the erythroid differentiation factor (EDF).

Activities of Mesoderm-Inducing Factors Secreted by Mammalian Cells in Culture : (mesoderm-induction/activin A/EDF/TGF-β family/embryonic induction).

We have examined the activities of several mesoderm-inducing factors contained in the culture fluids of phorbol ester (4beta-phorbol 12-myristate 13-acetate;PMA)-stimulated human cell lines. Mesoderm induction was assayed by examining the differentiation of mesoderm tissues reacted with presumptive ectoderm of the Cynops blastula. The assay system also examined erythroid differentiation activity (EDF activity) in order to test the relationship between mesoderm induction and activin A (EDF).

Mesodermal induction in early amphibian embryos by activin A (erythroid differentiation factor).

Recently the mesoderm-inducing effects of the transforming growth factor β (TGF-β) family of proteins have been widely examined. In an attemt to elucidate the functions of these proteins, porcine inhibin A and activin A (erythroid differentiation factor; EDF) were examined. Treatment of explants with activin A led to differentiation of mesodermal derivatives such as mesenchyme, notochord, blood cells and muscle, but inhibin A had a much lesser effect.