Van Hove Singularity and Enhanced Superconductivity in Ca-Intercalated Bilayer Graphene Induced by Confinement Epitaxy.

We demonstrate the impact of high-density calcium introduction into Ca-intercalated bilayer graphene on a SiC substrate, wherein a metallic layer of Ca has been identified at the interface. We have discerned that the additional Ca layer engenders a free-electron-like band, which subsequently hybridizes with a Dirac band, leading to the emergence of a van Hove singularity. Coinciding with this, there is an increase in the critical temperature for superconductivity. These findings allude to the manifestation of Ca-driven confinement epitaxy, augmenting superconductivity through the enhancement of attractive interactions in a pair of electron and hole bands with flat dispersion around the Fermi level.

Rhombohedral Boron Monosulfide as a p-Type Semiconductor.

Two-dimensional materials have wide ranging applications in electronic devices and catalysts owing to their unique properties. Boron-based compounds, which exhibit a polymorphic nature, are an attractive choice for developing boron-based two-dimensional materials. Among them, rhombohedral boron monosulfide (r-BS) has recently attracted considerable attention owing to its unique layered structure similar to that of transition metal dichalcogenides and a layer-dependent bandgap. However, experimental evidence that clarifies the charge carrier type in the r-BS semiconductor is lacking. In this study, we synthesized r-BS and evaluated its performance as a semiconductor by measuring the Seebeck coefficient and photo-electrochemical responses. The properties unique to p-type semiconductors were observed in both measurements, indicating that the synthesized r-BS is a p-type semiconductor. Moreover, a distinct Fano resonance was observed in Fourier transform infrared absorption spectroscopy, which was ascribed to the Fano resonance between the E(2) (TO) phonon mode and electrons in the band structures of r-BS, indicating that the p-type carrier was intrinsically doped in the synthesized r-BS. These results demonstrate the potential future application prospects of r-BS.

Tie2-Cre-Induced Inactivation of Non-Nuclear Estrogen Receptor-α Signaling Abrogates Estrogen Protection Against Vascular Injury.

Using the Cre-loxP system, we generated the first mouse model in which estrogen receptor-α non-nuclear signaling was inactivated in endothelial cells. Estrogen protection against mechanical vascular injury was impaired in this model. This result indicates the pivotal role of endothelial estrogen receptor-α non-nuclear signaling in the vasculoprotective effects of estrogen.

Direct Imaging of Band Structure for Powdered Rhombohedral Boron Monosulfide by Microfocused ARPES.

Boron-based two-dimensional (2D) materials are an excellent platform for nanoelectronics applications. Rhombohedral boron monosulfide (r-BS) is attracting particular attention because of its unique layered crystal structure suitable for exploring various functional properties originating in the 2D nature. However, studies to elucidate its fundamental electronic states have been largely limited because only tiny powdered crystals were available, hindering a precise investigation by spectroscopy such as angle-resolved photoemission spectroscopy (ARPES). Here we report the direct mapping of the band structure with a tiny (∼20 × 20 µm2) r-BS powder crystal by utilizing microfocused ARPES. We found that r-BS is a p-type semiconductor with a band gap of >0.5 eV characterized by the anisotropic in-plane effective mass. The present results demonstrate the high applicability of micro-ARPES to tiny powder crystals and widen an opportunity to access the yet-unexplored electronic states of various novel materials.

Bandgap widening through doping for improving the photocatalytic oxidation ability of narrow-bandgap semiconductors.

The trade-off relationship between narrowing the bandgap and achieving sufficient redox potentials accounts for the hindrance to the development of an efficient photocatalyst. Most of the previous researchers attempt to narrow the bandgap of semiconductors by impurity doping to achieve visible-light sensitivity, but this approach causes the losses of their oxidation and/or reduction ability. Conversely, this study presents a bandgap widening strategy by doping to improve the redox potential of photogenerated carriers. Employing first-principles simulations, we propose the lanthanum-doped bismuth vanadate (La-BiVO4) photocatalyst as a wider-bandgap semiconductor exhibiting stronger oxidation ability compared to pristine BiVO4, and the results revealed that the bismuth orbital in the valence band (VB) was diluted by lanthanum-ion doping, while the VB shifted to a higher potential (positively shifted). Thereafter, a La-BiVO4 powder was synthesized via a solid-state reaction, after which its activity was evaluated in the photocatalytic oxidation of 2-propanol (IPA). La-BiVO4 exhibited bandgap widening; thus, the number of absorbed photons under visible-light irradiation was lower than that of pristine BiVO4. However, the quantum efficiency (QE) of La-BiVO4 for the oxidation of IPA was higher than that of the pristine BiVO4. Consequently, the photocatalytic reaction rate of La-BiVO4 was superior to that of pristine BiVO4 under the same visible-light irradiation conditions. Although the bandgap of La-BiVO4 is widened, it is still sensitive to the cyan-light region, which is the strongest in the sunlight spectrum. These results demonstrate that the orbital dilution strategy by impurity elemental doping is effective for bandgap widening and contributes to improving the oxidation and/or reduction ability of the photogenerated charge carriers. This study elucidates the possibility of boosting photocatalytic performances via bandgap widening.

A pacing-controlled protocol for frequency-diastolic relations distinguishes diastolic dysfunction specific to a mouse HFpEF model.

Heart failure with preserved ejection fraction (HFpEF), characterized by diastolic dysfunction and insufficient exercise capacity, is a growing health problem worldwide. One major difficulty with experimental research on HFpEF is the lack of methods to consistently detect diastolic dysfunction in mouse models. We developed a pacing-controlled pressure-volume (PV) loop protocol for the assessment of diastolic function at different heart rates in mice and tested if the protocol could detect diastolic dysfunction specific to a HFpEF model. A HFpEF model was generated by high-fat diet (HFD) feeding with concomitant NG-nitro-l-arginine methyl ester administration, and a pressure-overload hypertrophy (PO) model was produced by surgical constriction of the transverse aorta (TAC). Heart rate (HR) was slowed below 400 beats/min by intraperitoneal injection of ivabradine. PV loop data were acquired and analyzed at HR incrementing from 400 to 700 beats/min via atrial pacing using a miniature pacing catheter inserted into the esophagus, and comparisons were made among control, HFpEF, and PO mice. At baseline without pacing, no diastolic abnormalities were detected in either PO or HFpEF models. Frequency-diastolic relations, however, revealed the significant diastolic impairment specific to the HFpEF model; both relaxation time constant (Tau) and end-diastolic pressure-volume relationship (EDPVR) were worsened as heart rate increased. Peak positive first derivative of left ventricular pressure (dP/dtmax) was significantly lower in HFpEF versus controls only at a high HR of 700 beats/min. A pacing-controlled protocol would be a feasible and potent method to detect diastolic dysfunction specific to a mouse HFpEF model.NEW & NOTEWORTHY We developed a pacing-controlled PV loop protocol for the assessment of diastolic function at different heart rates in mice, which is a feasible and potent method for the characterization of diastolic dysfunction in a murine HFpEF model whose diastolic dysfunction might be difficult to be detected under resting conditions without pacing.

Sex Differences and Regulatory Actions of Estrogen in Cardiovascular System.

Great progress has been made in the understanding of the pathophysiology of cardiovascular diseases (CVDs), and this has improved the prevention and prognosis of CVDs. However, while sex differences in CVDs have been well documented and studied for decades, their full extent remains unclear. Results of the latest clinical studies provide strong evidence of sex differences in the efficacy of drug treatment for heart failure, thereby possibly providing new mechanistic insights into sex differences in CVDs. In this review, we discuss the significance of sex differences, as rediscovered by recent studies, in the pathogenesis of CVDs. First, we provide an overview of the results of clinical trials to date regarding sex differences and hormone replacement therapy. Then, we discuss the role of sex differences in the maintenance and disruption of cardiovascular tissue homeostasis.

Synthesis, Structure, and Anomalous Magnetic Ordering of the Spin-1/2 Coupled Square Tetramer System K(NbO)Cu4(PO4)4.

Quasi-zero-dimensional antiferromagnets with weakly coupled clusters of multiple spins can provide an excellent platform for exploring exotic quantum states of matter. Here, we report the synthesis and the characterization of a copper-based insulating antiferromagnet, K(NbO)Cu4(PO4)4. Single-crystal X-ray diffraction measurements reveal that the crystal structure belongs to the tetragonal space group P4/nmm, in which Cu2+ ions align to form a quasi-two-dimensional layer of spin-1/2 coupled square tetramers. The structure is quasi-isostructural to recently reported magnetoelectric antiferromagnets, A(TiO)Cu4(PO4)4 (A = Ba, Sr, and Pb) with the P4212 space group. Despite their structural similarities, whereas the antiferromagnetic transition in A(TiO)Cu4(PO4)4 produces conventional anomalies in magnetization and heat capacity, that in K(NbO)Cu4(PO4)4 has several unusual features such as an upturn in magnetic susceptibility and a very weak specific heat anomaly that corresponds to a spin entropy release as small as 3%. These results indicate that the magnetism of K(NbO)Cu4(PO4)4 is far different from that of A(TiO)Cu4(PO4)4 and suggest that the ground state is very close to a quantum nonmagnetic singlet state. The origin of the distinct magnetism in K(NbO)Cu4(PO4)4 is discussed in terms of structural modifications of a Cu4O12 unit forming a square tetramer. Our study demonstrates that the present material family, represented by an extended chemical formula A(BO)Cu4(PO4)4 (AB = KNb, BaTi, SrTi, and PbTi), has broad chemical controllability of their magnetism. This makes this system an attractive material platform to study the physics of quantum spin-1/2 coupled square tetramers.

Migration of Deformable Vesicles Induced by Ionic Stimuli.

We have investigated the dynamics of phospholipid vesicles composed of 1,2-dioleoyl- sn-glycero-3-phosphocholine triggered by ionic stimuli using electrolytes such as CaCl2, NaCl, and NaOH. The ionic stimuli induce two characteristic vesicle dynamics, deformation due to the ion binding to the lipids in the outer leaflet of the vesicle and migration due to the concentration gradient of ions, that is, diffusiophoresis or the interfacial energy gradient mechanism. We examined the deformation pathway for each electrolyte as a function of time and analyzed it based on the surface dissociation model and the area difference elasticity model, which reveals the change of the cross-sectional area of the phospholipid by the ion binding. The metal ions such as Ca2+ and Na+ encourage inward budding deformation by decreasing the cross-sectional area of a lipid, whereas the hydroxide ion (OH-) encourages outward budding deformation by increasing the cross-sectional area of a lipid. When we microinjected these electrolytes toward the vesicles, a strong coupling between the deformation and the migration of the vesicle was observed for CaCl2 and NaOH, whereas for NaCl, the coupling was very weak. This difference probably originates from the binding constants of the ions.

Discovery of a Fungal Multicopper Oxidase That Catalyzes the Regioselective Coupling of a Tricyclic Naphthopyranone To Produce Atropisomers.

Atropisomeric dinapinones A1 and A2 (DPA1 and DPA2) were isolated from a culture of Talaromyces pinophilus FKI-3864. Monapinone coupling enzyme (MCE), which dimerizes naphthopyranone monapinone A (MPA), was purified from a cell-free extract of T. pinophilus FKI-3864. MCE regioselectively dimerizes MPA at the 8,8'-positions to synthesize the atropisomers DPA1 and DPA2 in a ratio of approximately 1:2.5 without a cofactor. The optimal pH value and temperature for MCE were 4.0 and 50 °C, and the apparent Km and Vmax values for MPA were (72.7±23.2) µm and (1.21±0.170) µmol min-1 mg-1 protein. The MCE polypeptide is significantly homologous with multicopper oxidases. Heterologous expression of MCE and functional analysis confirmed that MCE catalyzes the regioselective coupling reaction of MPA to produce DPA. No fungal multicopper oxidase has previously been reported to catalyze regioselective intermolecular oxidative phenol coupling to produce naphthopyranone atropisomers.

Indications for suboptimal low-dose direct oral anticoagulants for non-valvular atrial fibrillation patients.

BACKGROUND: Direct oral anticoagulants (DOACs) have been developed for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). We conducted a retrospective cohort study of patients with NVAF who were newly treated with DOACs in a real-world clinical setting. METHODS: We retrospectively analyzed patients with NVAF newly treated with one of three DOACs-dabigatran, rivaroxaban, or apixaban-between January 1, 2013, and December 31, 2015. RESULTS: A total of 670 patients with NVAF who were newly prescribed one of the three DOACs were analyzed; 74 patients (10.9%) received dabigatran, 290 (43.3%) received rivaroxaban, and 306 (45.8%) received apixaban. Fifteen patients had thromboembolic events, almost half of which were due to discontinuation of DOACs. Six patients had major bleeding, although almost all were discharged with good neurological prognoses. A total of 129 patients were treated with a suboptimal low-dose DOAC; none experienced a thromboembolic event as long as the DOAC was taken regularly, and none of the patients in any of the three DOAC groups had major bleeding events. CONCLUSIONS: With good adherence, the clinical course associated with DOACs is comparatively good. In the future, suboptimal low-dose DOAC therapy may serve as an appropriate choice for some patients with a high risk of stroke and bleeding.

Numerical evaluation of electron repulsion integrals for pseudoatomic orbitals and their derivatives.

A numerical method to calculate the four-center electron-repulsion integrals for strictly localized pseudoatomic orbital basis sets has been developed. Compared to the conventional Gaussian expansion method, this method has an advantage in the ease of combination with O(N) density functional calculations. Additional mathematical derivations are also presented including the analytic derivatives of the integrals with respect to atomic positions and spatial damping of the Coulomb interaction due to the screening effect. In the numerical test for a simple molecule, the convergence up to 10(-5) hartree in energy is successfully obtained with a feasible cost of computation.